University of Groningen Hidradenitis suppurativa …...Hidradenitis suppurativa (HS) is a chronic...

University of Groningen

Hidradenitis suppurativaDickinson-Blok, Janine Louise

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HIDRADENITIS SUPPURATIVA FROM PATHOGENESIS TO EMERGING

TREATMENT STRATEGIES

Janine Louise Dickinson-Blok

ISBN: 978-90-367-8142-8

ISBN: 978-90-367-8141-1 (e-version)

© 2015 by J.L. Dickinson-Blok, Groningen, The Netherlands

Financial support for the publication of this thesis was provided by:

AbbVie BV, ALK-Abelló BV, Almirall, Celgene BV, Fagron BV, Flen Pharma, Galderma Benelux

BV, Janssen-Cilag BV, La Roche-Posay, Leo Pharma BV, Molnlycke Health Care, Rijksuniversiteit

Groningen, Studiefonds Dermatologie, Universitair Medisch Centrum Groningen, Will Pharma.

Design and layout: Arjan Veening, Id Graficus, Assen, The Netherlands

Printing: GVO drukkers & vormgevers B.V., Ede, The Netherland

HIDRADENITIS SUPPURATIVA FROM PATHOGENESIS TO EMERGING

TREATMENT STRATEGIES

PRoEfScHRIfT

ter verkrijging van de graad van doctor aan de

Rijksuniversiteit Groningen

op gezag van de

rector magnificus prof. dr. E. Sterken

en volgens besluit van het College voor Promoties.

De openbare verdediging zal plaatsvinden op

woensdag 30 september 2015 om 11.00 uur

door

Janine Louise Blok

geboren op 11 juli 1984

te Deventer

Promotor

Prof. dr. M.F. Jonkman

Copromotor

Dr. B. Horváth

Beoordelingscommissie

Prof. dr. B. van der Lei

Prof. dr. E.P. Prens

Prof. dr. G.B.E. Jemec

Paranimfen

Katarzyna Gostyńska

Ineke Janse

coNTENTS

List of abbreviations 7

Chapter 1. Introduction 9

Chapter 2. Increased expression of integrin α6β4 at the basement membrane 23

zone lining the sebaceous glands in hidradenitis suppurativa

Chapter 3. The possible association of hidradenitis suppurativa and Down 37

syndrome: are impaired Notch signaling and immunological

abnormalities the missing links?

Chapter 4. Gene expression profiling in skin and blood in hidradenitis 45

suppurativa

Chapter 5. Systemic therapy with immunosuppressive agents and retinoids 51

in hidradenitis suppurativa: a systematic review

Chapter 6. Ustekinumab in hidradenitis suppurativa: a clinical open label 79

study with analyses of the protein expression profile in serum

Chapter 7. Skin-tissue-sparing excision with electrosurgical peeling (STEEP): 97

a surgical treatment option for severe hidradenitis suppurativa

Hurley stage II/III

Chapter 8. Surgery under general anesthesia in severe hidradenitis 107

suppurativa: a study of 363 primary operations in 113 patients

Chapter 9. General discussion and future perspectives 125

Chapter 10. Dutch summary / Nederlandse samenvatting 137

Appendices List of publications 145

Dankwoord

Curriculum vitae

LIST of ABBREVIATIoNS

AE adverse event

BMZ basement membrane zone

DLQI daily life quality index

FPSU folliculopilosebaceous unit

HiSCR hidradenitis suppurativa clinical response

HS hidadenitis suppurativa

IF immunofluorescence

IFE interfollicular epidermis

IL interleukine

m-HSLASI modified hidradenitis suppurativa-lesion area and severity index

mSS modified Sartorius scale

PAS periodic acid–schiff

PGA physician’s global assessment

SFJ sebofollicular junction

STEEP skin tissue sparing excision with electrosurgical peeling

Th-cells T-helper cells

TNF-α tumor-necrosis-factor-α

VAS visual analogue scale

9

1INTRoDUcTIoN

J.L. Dickinson-Blok

10

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease affecting approximately

1-4% of the general population.1 The disease is characterized by painful deep-seated

nodules and abscesses. In a later stage, epitheliazed sinus tracts are formed in the dermis

and subcutaneous fat. The lesions seen in HS are mainly restricted to the body folds, like

the axillary, inguinal and anogenital regions.2 These locations have several characteristics

in common: 1) the skin contains apocrine glands, 2) a predisposition to mechanical friction

and 3) humid conditions. Lesions commonly heal with hypertrophic fibrous scarring resulting

in complete architectural loss, cosmetic disfigurement and in some cases even movement

impairment.3 Not surprisingly, patient’s quality of life is impaired to a great extent.4 In fact,

it has been found that quality of life scores are worse in HS compared to other distressing

chronic dermatoses like atopic dermatitis, psoriasis, Darier’s disease and Hailey-Hailey disease.5

In addition to their professional career, patient’s intimate, sexual and social relationships are

adversely affected by the disease. HS has also an impact on society, as it is associated with

frequent and/or long-term sick leaves.6 Due to embarrassment, ignorance and neglect of

the patient, as well as a lack of knowledge of regarding HS under certain medical specialists,

diagnostic delays of several years are not uncommon.7,8

Pathogenesis

The pathogenesis of HS is still largely unknown. The term hidradenitis suppurativa dates

back to a time where it was assumed to be primarily a disease of the apocrine sweat glands.3

Although, it is now generally accepted that the hair follicle is primarily involved while the

associated apocrine gland is affected in only the minority of patients as a secondary event

(figure 1).9

The role of bacteria in this inflammatory process remains elusive. Fulminant discharge suggests

bacterial involvement but cultures in microbiological studies have been shown to be negative

or mainly revealed commensal bacteria of the skin or intestine, dependent on the investigated

body location.10-12 Psoriasiform hyperplasia, follicular hyperkeratosis and occlusion are early

events in the disease process.13-15 It has been suggested that these histopathological changes

result from subclinical inflammation initiated by keratinocytes reacting to commensal skin

bacteria.16 Additionally, a recent study suggested that fragility of the sebofollicular junction

(SFJ) as part of the folliculopilosebaceous unit (FPSU) could contribute to the inflammatory

activity by a defect in the follicular basement membrane zone (BMZ) that allows the release of

follicular content into the surrounding dermis.17 Massive inflammation as a result of immune

system activation occurs upon complete rupturing of the occluded hair follicle.

11

Figure 1. The folliculopilosebaceous unit (FPSU) in the skin.

* sebofollicular junction (SFJ)

In addition, overproduction of interleukin (IL)-1β and tumor necrosis factor (TNF)-α from the

innate immune system as well as IL-10, IL-12, IL-17 and IL-23 from the adaptive immune

system have been demonstrated in HS skin.18,19 Epithelialized sinus tracts may be formed from

epithelial strands in the dermis in response to these cytokines. This may facilitate access for

(commensal) bacteria, leading to repetitive inflammation, further extension of the disease, and

subsequently a vicious circle is made with ever increasing architectural destruction. Unraveling

what cytokines are predominant in the inflammatory cascade is an important step for a better

understanding of the HS pathogenesis and for identifying therapeutic targets.

Epidemiology

The prevalence of HS varies between studies and is estimated to be 1-4% in Europe, these

numbers are mostly derived from population based questionnaires.20,21 Substantial lower

prevalence rates were found in the United States, varying from 0.053 to 0.078%.22,23 Females

are three times more often affected than men.1,20,24 First symptoms typically occur in the

second or third decades of life but disease onset during childhood is not exceptional.25-27

Sebaceous gland

Apocrine gland

Hair follicle

FPSU

Epidermis

Dermis

Subcutaneous fat

12

About 80% of HS patients has a history of smoking, making it a well-known risk factor for

HS.20,24,28,29 The exact pathogenic mechanism remains unclear, however, tobacco smoking

may induce HS by promoting follicular occlusion, augmenting the innate immune system and

triggering pro-inflammatory cytokine release.30 The association between obesity and HS has

also widely been recognized and may result from increased mechanical friction of the skin

and inducing a pro-inflammatory state.20,29,31 Both smoking and obesity are associated with

higher disease severity.31 The role of hormones in HS remains controversial, especially regarding

androgens. Studies have shown that HS improves in women on anti-androgen therapy.32,33

Also, HS rarely develops in postmenopausal women, a phase in life that is characterized by

relative hypo-androgenism.34 However, it has been demonstrated that free androgen levels

are not consistently elevated in women with HS.35 Multiple studies have suggested that HS

is associated with several co-morbidities, including morbus Crohn, metabolic syndrome,

hypertension, diabetes mellitus and polycystic ovarian syndrome (PCOS).23,36-38 Finally, it has

been recognized that HS runs in families, indicating that genetic factors are also important.(24) In fact, loss-of-function mutations in genes encoding for the g-secretase protein complex

have been identified in familial HS.39,40 Inactivation of g-secretase may result in altered

Notch signaling which may promote the formation of epidermal cysts and contribute to the

continuing inflammatory activity in HS by dysfunction of the innate immune system.30

classification and monitoring disease severity

There is wide diversity in the clinical appearance of HS regarding severity, disease location and

whether there is predomination of inflammatory nodules or sinus tracts and fistulas. The Hurley

classification (grade I through III) is a well-known and commonly used system to express

disease severity by determination of the character and the extensiveness of the lesions

(figure 2).41

13

Figure 2. The Hurley stages of lesions in HS.

Although the Hurley classification is convenient to use in daily practice, its major disadvantage

is that it is a static rather than a dynamic scoring system and therefore inappropriate for

monitoring therapeutic effects over time. In recent years, several dynamic scoring systems

have been developed, including the modified Sartorius score (mSS)29 and the Hidradenitis

Suppurativa Clinical Response (HiSCR).42 The recently proposed HiSCR is actually the first

Hurley I

Localized disease.

Single or multiple abscesses.

No sinus tracts or scarring.

Hurley II

Recurrent abscesses.

Single or multiple sinus tracts and

scarring.

Lesions separated by healthy skin.

Hurley III

Multiple interconnected abscesses and

sinus tracts.

Involvement of the entire affected area.

14

score defining a validated practical clinical endpoint.42 Unfortunately, in previous studies no

uniformly applied clinical endpoint was applied to assess treatment effectiveness, making it

difficult to compare these trials with each other. The identification of a specific biomarker for

HS could support disease monitoring. Recent evidence suggests that the soluble IL-2 receptor

(sIL2R) and S100A8/A9 may be putative candidates for distinguishing HS patients from healthy

controls.43,44 However, more studies are needed to establish their usefulness in monitoring

treatment efficacy and to identify other potential biomarkers.

Treatment of HS

Treatment of HS is a challenge as many patients are resistant to therapy. Recently Zouboulis et

al.45 developed a treatment guideline for HS. Although this guideline is of great help in ordering

the currently available therapeutic options, the evidence for individual therapies remains

relatively sparse. Three primary goals should be pursued in the treatment of HS: 1) to treat

acute painful lesions, 2) to heal chronic lesions in the maintenance phase and 3) to prevent

the development of new lesions. The main general therapeutic options are topical agents,

systemic medication and surgical interventions. The strategy for achieving the treatment goals

is dependent on the severity of HS and the expertise of the center of treatment. The Hurley

classification is a practical tool to give direction to the choice of therapy.

Topical therapies

The only topical treatments that have been studied in HS are resorcin 15% cream and topical

clindamycin.46 These agents can be applied as monotherapy in Hurley stage I disease. In Hurley

stage II or III disease it is mainly used as adjuvant or as maintenance therapy. Acute painful

lesions may be treated with intralesional triamcinolon 0.1% acetonide 10 mg/ml.

Systemic therapies

Systemic agents comprise anti-inflammatory, immunosuppressive medication and retinoids.

Systemic antibiotics are used for both their anti-inflammatory and anti-bacterial effect. These

agents are indicated for Hurley II and III disease as well as in widely spread Hurley I disease.

The choice for a specific systemic antibiotic is mainly dependent on clinical experience, as

studies are still limited. Most evidence exists for oral tetracyclin and combinational therapy

with clindamycin and rifampicin.47-50 The systemic retinoids acitretin and isotretinoin were

introduced to the therapeutic arsenal of HS based on their immunomodulatory effects and

15

their ability to normalize epithelial cell differentiation. Immunosuppressive therapy is indicated

in severe inflammatory disease (Hurley stage II or III) and a wide variety of agents has been

studied, including dapsone, methotrexate, ciclosporin and biologicals, like the TNF-α inhibitors

infliximab and adalimumab. Unfortunately, the quality of performed studies is frequently poor

and the number of randomized controlled trials is only limited. Therefore, consensus on what

systemic agent is most effective in HS is still not achieved.

Surgical treatment

Surgery is required for Hurley stage II and III disease, as epithelialized cysts and sinus tracts

will still remain present once inflammation has been treated. In the acute phase simple incision

and drainage is appropriate for relieving pressure of acute painful abscesses. However, this is a

symptomatic rather than a definite treatment, as lesions will recur. Therefore, surgical removal

of all lesional tissue is the preferred approach in HS. Sparing healthy tissue to a maximum while

lesional tissue is completely removed could be an appropriate surgical aim in HS. This aim may

be achieved with the deroofing technique.51,52 The so-called deroofing is a suitable technique

for Hurley stage I or limited stage II disease as lesions are superficially removed. However,

in severe HS deroofing does not suffice since lesions may extend into the subcutaneous fat.

Furthermore, severe HS is frequently dominated by fibrotic tissue, which cannot be removed

during deroofing. Removal of this tissue is of importance as it may contain skin appendages

that serve as a source of recurrence, and prevent adequate wound contraction and subsequent

healing. Therefore in moderate to severe HS, wide excision of the entire affected area is

frequently used, especially by surgeons.53 A disadvantage of this approach is that it causes large

defects with a serious risk on contracture formation and long healing times. Surgery may be

performed with cold steel, electrosurgery or a CO2 laser.52,54,55 Finally, several types of wound

healing techniques have been proposed for HS, including healing by secondary intension or

primary closure by sutures, skin grafts or flaps.9 Exploring current and new surgical approaches

in severe HS is needed to identify what techniques are superior regarding surgical outcomes in

terms of radical lesional tissue removal, healing time and complications.

In conclusion, treatment of HS is still difficult despite the numerous options, leading to

frustration in both patients and in doctors. Studies are needed to investigate currently available

treatments and to explore new systemic and surgical treatments for the development of

general treatment guidelines.

16

AIMS AND oUTLINE of THIS THESIS HS has a severe impact on quality of life and treatment is, despite the numerous options,

in many cases still unsatisfactory. To develop new and improved treatment strategies, the

fundamentals of the pathogenesis of HS need to be further unraveled. Furthermore, clinical

trials are needed to investigate the effectiveness of (new) systemic and surgical treatments as

well as to determine their therapeutic value in HS.

The aims of this thesis are:

To investigate the principles of the HS pathogenesis by focusing on histopathological 1.

changes of the hair follicle and to study the role of specific protein upregulation in the

inflammatory cascade.

To study the effectiveness of established and new systemic agents for the treatment of HS.2.

To explore new surgical techniques to provide tools for clinicians dealing with HS. 3.

Chapter 2 describes the expression of the main glycoproteins at the basement membrane

zone in pilosebaceous units of HS patients by performing immunofluorescence stainings on

perilesional skin.

In Chapter 3 an association between Down’s syndrome and HS is hypothesized based on

defective Notch signaling as a result of functional g-secretase deficiency.

Chapter 4 describes the gene expression profile of hidradenitis suppurativa in skin and blood.

In Chapter 5 we systematically review the current literature to explore the effectiveness of

systemic treatment with immunosuppressive agents and retinoids in HS.

In Chapter 6 the effectiveness and safety of the IL-12/IL-23 inhibitor ustekinumab is

prospectively studied in HS patients.

Chapter 7 and 8 focus on the skin tissue sparing excision with electrosurgical peeling (STEEP)

technique as a surgical method for moderate to severe HS and describes its results over a time

span of 14 years.

Chapter 9 summarizes the main findings of this thesis and provides a general discussion for

future studies.

17

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21

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23

2INcREASED ExPRESSIoN of INTEgRIN α6β4 AT THE BASEMENT MEMBRANE zoNE LININg THE SEBAcEoUS gLANDS IN HIDRADENITIS SUPPURATIVA

J.L. Blok, I.C. Janse, B. Horváth, M.F. Jonkman

Department of Dermatology, University Medical Center Groningen, University of Groningen,

Groningen, the Netherlands

Acta Derm Venereol. 2015 Jun 30. doi: 10.2340/00015555-2186. [Epub ahead of print]

24

ABSTRAcTThe pathogenesis of hidradenitis suppurativa (HS) is still elusive. A recent study of the

folliculopilosebaceous unit (FPSU) in HS patients showed that the basement membrane zone

(BMZ) of the sebofollicular junction was almost devoid of periodic acid–schiff (PAS) positive

material, a staining method for glycoproteins. By performing PAS and immunofluorescence

stainings for type XVII collagen, type VII collagen, laminin-332 and integrin α6β4 on skin

biopsies from body folds of patients and controls, we aimed to identify whether these

glycoproteins are differently expressed in HS. We found normal PAS staining along the

sebofollicular junction in HS, and could therefore not confirm any weakening of the BMZ.

Conversely, we demonstrated increased expression of integrin α6β4 lining the sebaceous

glands in HS patients. The other BMZ components were normally expressed. Enhanced

expression of integrin α6β4 along sebaceous glands in HS could result from alterations in the

skin microbioma and enhance inflammation.

25

INTRoDUcTIoNHidradenitis suppurativa (HS) is a chronic inflammatory skin disease characterized by recurrent

painful nodules, abscesses, sinus tracts and scarring. The disease is primarily located at the

apocrine gland bearing skin, including the armpits and groins.1 Quality of life in HS patients is

severely affected due to the appearance of the skin, associated pain and the filthy odor that is

often secreted from the inflammatory lesions.2

The pathogenesis of HS has not been clarified yet. Several histological studies have shown

that the hair follicle is involved at an early stage of the disease process.3-6 These studies

demonstrated that follicular occlusion is present in the majority of patients, an event that

eventually results in rupturing of the hair follicle with subsequent inflammation and sinus

tract formation. However, the question remains what the driving mechanism behind this

follicular occlusion is. In a recent study, diminished periodic acid schiff (PAS) staining was

found at the basement membrane zone (BMZ) of the sebofollicular junction (SFJ) at the

folliculopilosebaceous units (FPSU) of HS patients.3 Since this deficiency was also found in

perilesional skin, the authors suggest that the PAS-negative gaps represent primary defects

in the BMZ leading to fragility of the hair follicle. Consequently there is release of follicular

contents into the dermis, triggering an inflammatory reaction. Diminished expression in one of

the glycoproteins in the BMZ of the SFJ might explain the PAS-gaps. However, there was not

stained for specific glycoproteins. The aim of this study was to document the expression of the

most important BMZ components, including type XVII collagen, type VII collagen, laminin-332,

and integrin α6β4, of the follicular epidermis relative to the interfollicular epidermis in HS, and

to compare the expression ratio with healthy controls.

26

MATERIAL AND METHoDS Design and setting

This study was performed at the department of Dermatology at the University Medical Center

Groningen. The local institutional review board approved the study.

Patients

Patients who were scheduled for surgical treatment of HS with the deroofing technique or

the STEEP procedure4,5 were included after written informed consent was obtained. Healthy

volunteers were considered eligible for participation when they had no skin disease at the

armpits and had given written informed consent. The age of all individuals was 18 years or

older.

Collection procedure

Up to 17 perilesional samples were obtained from axillary or inguinal HS skin by four mm

punch biopsy, immediately frozen in liquid nitrogen, and subsequently stored at -80 degrees

Celsius. Additionally, after injection with local anaesthesia consisting of 1cc 1% lidocaine/

adrenaline (1: 200.000), four mm punch biopsies were obtained from axillary skin of eight

healthy volunteers that served as controls. Skin samples lacking an associated sebaceous gland

with the hair follicle were excluded.

Staining procedure

PAS staining of the skin samples was performed. Briefly, after periodic acid solution oxidation,

tissue sections were immerged in Schiff’s reagent and counterstained with hematoxylin.

Immunofluorescence (IF) staining for type XVII collagen, type VII collagen, laminin 332,

integrin α6 and β4 was performed. The procedures for IF staining and image collection

have been described in detail previously.6 The following monoclonal antibodies were used:

VK1 against type XVII collagen (dr. H. H. Pas, Groningen, The Netherlands), LH7:2 against

collagen type VII (gift from Dr I. Leigh, London, UK), K140 against laminin β3 (gift from

dr. M. Marinkovich, Stanford, U.S.A.), 58xβ4 against integrin β4 (gift from dr. Sonnenberg,

Amsterdam, Netherlands) and GOH3 against integrin α6 (gift from dr. Sonnenberg,

Amsterdam, Netherlands). Fluorescein-conjugated goat anti rat IgG (Southern Biotechnology

Associates, Birmingham, U.S.A) and Alexa 488-conjugated goat anti mouse IgG (Molecular

Probes, Eugene, U.S.A) were used as secondary steps.

27

Assessments and statistical analysis

The intensity of the stainings was measured at the 6 segments of the FPSU: 1) the interfolliclar

epidermis (IFE), 2) the superior segment (SS) of the hair follicle, 3) the inferior segment (IS) of

the hair follicle, 4) the sebofollicular junction (SFJ) and 5) the sebaceous gland (SG). The SS was

defined as the part of the hair follicle extending from the IFE to the SFJ. The IS was defined as

the part extending from the SFJ to the bulb. The SFJ was defined as the transition zone from

the hair follicle to the sebaceous gland. The SFJ of skin samples stained with IF was identified

by the presence of fat globules characteristic of the sebaceous gland and by comparison of the

skin sample with the PAS staining of that same biopsy. For each skin sample the intensity of

all performed PAS and IF stainings at the aforementioned individual segments were analyzed

using Image J software. Subsequently, the ratio of individual segments to the IFE was calculated

for both the PAS and IF stainings, with the IFE serving as an internal control for each skin

sample. The Mann-Whitney U test was performed to compare the differences in these ratios

between patients and controls.

28

RESULTS Skin biopsies were obtained from a total of 17 HS patients and eight controls. Biopsies of ten

patients and two controls were excluded due to the lack of an associated sebaceous gland.

Eventually, biopsies of seven HS patients (two women, five men) and six controls (three

women, three men) were studied.

PAS staining

As previously described by Danby et al.3 the IFE showed a continuous and regular PAS staining

pattern in all biopsies with a mean intensity of 143.8 pixels (SD 11.6) in controls and 150.0

pixels (SD 10.5) in patients. Therefore, the IFE served as a suitable internal control. There

were no statistically significant differences between the ratios of the mean intensity of the PAS

staining at the individual segments of the FPSU to the IFE in patients and controls (figures.

1-2).

Type VII collagen, type XVII collagen, laminin 332

For these IF stainings no statistically significant differences were found between patients and

controls in the ratios of the mean staining intensity at the individual FPSU segments to the IFE.

Integrin β4 and α6

At the sebaceous gland, the mean intensity of integrin β4 declined compared to the IFE in

both patients and controls (figures. 1-2). The ratio of the mean intensity of integrin β4 at the

sebaceous gland to the IFE was significantly higher in patients (0.41) compared to controls

(0.14) (p=0.004). This implicates that integrin β4 expression at the sebaceous gland was

relatively higher in patients. IF-staining for integrin α6 also revealed a significantly (p=0.011)

higher level of expression at the sebaceous gland in HS compared to controls (figures. 1-2). It

is plausible that the expression patterns of integrin α6 en β4 followed the same pattern, since

they are dimerized in the integrin α6β4-complex. The relative expression of integrin α6β4 was

not altered at the remaining FPSU segments in HS compared to controls.

29

Figure 1. PAS and IF staining of the IFE and SFJ/SG in control and patient skin.

There were no differences in the intensity of the PAS staining between the IFE and the SFJ/SG

in both controls and patients. The ratio of the staining intensity of integrin α6 and β4 of the

SG to the IFE is higher in patients than in controls. Scale bar = 20 µm.

Control skin

Patient skin

IFE

SS

IS

SFJSG

PAS Integrin β4 Integrin α6

Integrin α6PAS Integrin β4

IFE

SS

SFJSG

IS

30

Figure 2. Ratio of PAS and integrin α6β4 expression compared to the IFE.

The bars represent the ratio of the mean PAS and integrin α6β4 staining intensities of the

individually assessed folliculopilosebaceous segments to the IFE.

IFE: interfollicular epidermis; SS: superior segment; SFJ: sebofollicular junction; SG: sebaceous

gland; IS: inferior segment. *statistically significant difference

1,1 1

0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1

0

Rat

io s

egm

ent

to IF

E

FPSU segment

PAS PatientControls

1,1 1

0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1

0

Rat

io s

egm

ent

to IF

E

FPSU segment

Integrin β41,1

1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1

0

Rat

io s

egm

ent

to IF

E

FPSU segment

Integrin α4

31

DIScUSSIoN This study demonstrates that integrin α6β4 was relatively upregulated along the BMZ of the

sebaceous glands in HS patients. In contrast to Danby et al,3 reduced PAS positivity at the

SFJ in HS was not observed, neither did we find any differences in PAS positivity within the

remaining hair follicle segments. Therefore, we cannot confirm that BMZ fragility at the SFJ is

responsible for leakage of follicular content into the surrounding dermis.

One can speculate about the cause and consequences of integrin α6β4 upregulation in HS.

Integrins are a family of heterodimeric glycosylated transmembrane receptors. They come

primarily to expression in organs lined with stratified epithelium, like the skin and lungs. In

human epidermis, integrin expression is restricted to the basal layer.7 The β4 integrins are

primarily found at the basement membrane zone where they are located transmembranous

in hemidesmosomes. In addition to an adhesive function, integrins are important signaling

molecules that have bidirectional actions. Integrins show affinity to several extracellular proteins

and are therefore involved in a variety of pathological processes, including oncogenesis,

immune responses and inflammatory reactions.8,9 In HS integrines possibly have a cell

signaling function. For instance, previous studies on pulmonary tissue have demonstrated

that integrin β4 expression increased upon binding with pathogenic microorganisms.8,10 It has

been hypothesized that integrines, just as toll-like receptors, function as pattern recognition

receptors (PRRs) that upon interaction with bacteria induce cellular responses that acitivate

the innate immune system and inflammation.8 The role of bacteria in the pathogenesis of HS

is still elusive, as previous microbiological studies found a wide range of bacteria associated

with HS.11-13 However, new molecular techniques using a genomic approach revealed that

there is greater bacterial diversity in the skin than previously assumed based on results of

culturing methods.14 Van der Zee et al,15 hypothesized that alterations in the microbioma

of HS skin stimulate keratinocytes to produce antimicrobial peptides and pro-inflammatory

cytokines, resulting in the typical histological changes observed early on in the disease process.

Additionally, alterations in the microbioma could explain why HS lesions are mainly localized

at the body folds, as the bacterial community is different in these moist areas compared to the

relatively dry areas of the body.14,16 Similar to lung tissue, changes in the bacterial community

are possibly responsible for the integrin α6β4 upregulation we found in HS patients and may

contribute to activation of the immune system. Finally, increased expression of α6β4 may also

contribute to the development of squamous cell carcinoma (SCC), a well-known complication

of HS.17,18 In fact, mice with aberrant α6β4 expression showed a greater infiltration of

immunosuppressive cells during tumor promotion, a phenomenon that may contribute to the

susceptibility of SCC formation.18

32

In conclusion, in this study we demonstrate that integrin α6β4 is upregulated in sebaceous

glands of HS patients. This upregulation could result from alterations in the skin microbioma

and may contribute to the inflammatory reaction seen in HS as well as to the increased risk of

SCC development in HS. Integrin α6β4 could therefore be a putative treatment target for HS in

the future. Characterization of the skin microbioma in more detail could provide further insight

in the role of bacteria in HS and may provide a rationale for specific antibiotic treatments.

33

REfERENcES


Matusiak L, Bieniek A, Szepietowski JC. Psychophysical aspects of hidradenitis suppurativa. 2.



suppurativa may be due to defective follicular support. Br J Dermatol 2013;168:1034-1039.

Blok JL, Spoo JR, Leeman FW, Jonkman MF, Horvath B. Skin-Tissue-sparing Excision with 4.

Electrosurgical Peeling (STEEP): a surgical treatment option for severe hidradenitis suppurativa Hurley

stage II/III. J Eur Acad Dermatol Venereol 2015; 29:379-382.

van Hattem S, Spoo JR, Horvath B, Jonkman MF, Leeman FW. Surgical treatment of sinuses by 5.

deroofing in hidradenitis suppurativa. Dermatol Surg 2012; 38:494-497.

Vodegel RM, Jonkman MF, Pas HH, de Jong MC. U-serrated immunodeposition pattern differentiates 6.

type VII collagen targeting bullous diseases from other subepidermal bullous autoimmune diseases.

Br J Dermatol 2004;151:112-118.

Oldak M, Smola-Hess S, Maksym R. Integrin beta4, keratinocytes and papillomavirus infection.7.

Int J Mol Med 2006;17:195-202.

Ulanova M, Gravelle S, Barnes R. The role of epithelial integrin receptors in recognition of pulmonary 8.

pathogens. J Innate Immun 2009; 1:4-17.

Berman AE, Kozlova NI. Integrins: structure and functions. 9. Membr Cell Biol 2000;13:207-44.

Gravelle S, Barnes R, Hawdon N, Shewchuk L, Eibl J, Lam JS, et al. Up-regulation of integrin 10.

expression in lung adenocarcinoma cells caused by bacterial infection: in vitro study. Innate Immun

2010;16:14-26.




Sartorius K, Killasli H, Oprica C, Sullivan A, Lapins J. Bacteriology of hidradenitis suppurativa 12.

exacerbations and deep tissue cultures obtained during carbon dioxide laser treatment. Br J Dermatol

2012; 166:879-83.

34


are the Treatment of Choice? Acta Derm Venereol 2014; 94:699-702.

Grice EA, Segre JA. The skin microbiome. 14. Nat Rev Microbiol 2011; 9:244-53.



SanMiguel A, Grice EA. Interactions between host factors and the skin microbiome. 16. Cell Mol Life Sci

2015; 72:1499-1515.

Lavogiez C, Delaporte E, Darras-Vercambre S, et al. Clinicopathological study of 13 cases of 17.

squamous cell carcinoma complicating hidradenitis suppurativa. Dermatology 2010; 220:147-53.

Maalouf SW, Theivakumar S, Owens DM. Epidermal alpha6beta4 integrin stimulates the influx of 18.

immunosuppressive cells during skin tumor promotion. J Dermatol Sci 2012; 66:108-18.

35

37

3THE PoSSIBLE ASSocIATIoN of HIDRADENITIS SUPPURATIVA AND DowN SyNDRoME: ARE IMPAIRED NOTCH SIGNALING AND

IMMUNOLOGICAL ABNORMALITIES THE MISSING

LINKS?

J.L. Blok1, M.F. Jonkman1, B.Horváth1

1Department of Dermatology, University of Groningen, University Medical Center Groningen,

Hanzeplein 1, 9700 RB Groningen, the Netherlands

Published in the British Journal of Dermatology, 2014; 170:1375-77

38

ABSTRAcTHidradenitis suppurativa (HS) is an inflammatory skin disease of unknown origin. Recently, it

has been demonstrated that mutations in several genes encoding for the protease g-secretase

(GS), including presenilin-1 (PSEN1), probably play a major role in the pathogenesis through

impairment of the Notch signaling pathway. Mutations in PSEN1 are also associated with

Alzheimer’s disease (AD), a condition that is strongly related to Down syndrome (DS). HS

occuring in patients with DS has been described in only five patients so far. Here we describe

five new cases. An association between HS and DS is reasonable since trisomy of chromosome

21 leads to overexpression of the amyloid precursor protein (APP) resulting in a change of the

substrate pool for GS processing at the expense of the Notch receptors. Consequently, Notch

signaling is impaired in DS predisposing these individuals to HS. APP itself may also directly

influence keratinocytes resulting in the typical histopathological features seen in HS. Finally,

the relatively high prevalence of obesity amongst DS patients as well as alterations in their

immune system could underlie the possible association between both conditions. To confirm

our hypothesis, further studies are needed investigating the expression of Notch receptors and

APP in the epidermis of DS patients.

39

Hidradenitis suppurativa (HS) is an inflammatory skin disease that usually arises after puberty

and severely impairs quality of life. Smoking, obesity, genetics and abnormalities of the immune

system are important risk factors for the development of HS.(1) The latter makes that the

disease is generally responsive to immunosuppressive agents, including to tumor-necrosis-factor

(TNF)-α inhibitors.1 Our knowledge regarding the pathogenesis, risk factors and treatment may

be further enhanced by studying conditions that tend to co-occur with HS. Here, we describe

five cases where HS occurred in Down syndrome (DS). The cases are summarized in table 1

and figure 1. The disease characteristics and course of patients 1-3 have several similarities:

they have therapy resistant disease located at the (ano)genital area and a pre-pubertal onset.

Patients 4 and 5 are monozygotic twins whose other family members were not affected by HS.

DS is caused by trisomy of chromosome 21 and occurs in approximately 1 of 1000 newborns.

The co-occurrence of HS and DS has previously been described in three men and two

women.2-4 The phenotype of DS is complex and includes a broad range of cognitive and

neurological deficits. Two hypotheses have been proposed regarding the cause of the DS

phenotype: the “developmental instability hypothesis” states that developmental pathways

are disrupted through a general genetic imbalance whereas the “gene-dosage theory” implies

that increased expression of certain genes on chromosome 21 is responsible. We think that the

genetic abnormalities of DS might also predispose these individuals to the development of HS.

Previously, loss-of-function mutations in the genes encoding for the g-secretase (GS) complex

have been identified in familial HS, including nicastrin (NCSTN), presenilin-1 (PSEN1) and

presenilin enhancer 2 (PSENEN).5 GS is a transmembranous enzyme complex that enhances

intracellular Notch signaling by cleavage of the Notch receptor (figure. 2). Humans have four

Notch receptors of which Notch-1 and Notch-2 are predominantly expressed in the epidermis.6

GS-deficiency and inhibition of Notch-1 and -2 in mice causes replacement of hair follicles

by epidermal cysts and diminished sebaceous gland differentiation, which are typical features

of HS.5 Impaired Notch signaling also inhibits the generation of natural killer cells and causes

an insufficient suppression of the innate immune system once it is activated, resulting in a

compromised defense mechanism and continuing inflammatory activity, respectively.5 GS is

also a key player in the development of Alzheimer’s disease (AD). By the fourth decade of life

characteristic β-amyloid (Aβ) brain plaques start to develop in DS that eventually give rise to

AD. Aβ is a product resulting from GS-cleavage of the amyloid precursor protein (APP). APP

is also strongly expressed in the human epidermis.7 The gene encoding for APP has shown to

be located on chromosome 21 and its expression is therefore, in accordance with the “gene

dosage hypothesis,” probably increased in DS. APP and one of its other cleavage products

sAPPα (secretory N-terminal ectodomain of APP) stimulate keratinocyte adhesion, migration

40

and proliferation.7 This makes DS patients prone to keratinocyte hyperproliferation and

follicular plugging, which are major histopathological features of HS. Furthermore, Berezovska

et al.8 demonstrated that APP and the Notch receptor are competitive substrates for GS and

that Notch-1 signaling was diminished in primary neurons overexpressing APP. The increased

amounts of APP that need to be processed by GS in DS might therefore occur at the expense

of Notch processing. The genes encoding for the Notch receptors and GS are in contrast to APP

not located on chromosome 21. Thus, increased APP expression might represent the missing

link between HS and DS by enhancing keratinocyte activity as well as by being a competitive

substrate for Notch receptors, leading to impairment of Notch-1 and -2 signaling (figure. 2).

Finally, obesity and a dysregulated immune system might also contribute to an association

between DS and HS. The majority of the patients in our case series were overweight or obese

(four out of five patients). Indeed, the prevalence of obesity is higher in children with DS

compared to healthy children, making them more prone for the development of HS as well

as to a more severe course of the disease. Additionally, DS patients are more susceptible to

the development of infections and autoimmune disorders, like celiac disease, due to intrinsic

immunological defects.9 With five new cases we strengthen the thought that DS and HS are

associated. We hypothesize that this results from increased APP expression, an altered immune

system and increased prevalence of obesity in DS. Further studies comparing the expression of

Notch receptors and APP in the epidermis of DS patients and controls are needed to confirm

our hypothesis.

Patient 1 Patient 2 Patient 3 Patient 4a Patient 5a

Seks Female Female Male Female Female

Age (years) 14 16 13 24 24

Age at disease onset (years) 9 10 13 20 20

BMI (kg m-2) 33.1 22.9 27.1 35.2 37.2

Family history Negative Negative Negative Negativeb Negativeb

Location affected by HS Genital area Anogenital area Genital area and upper

legs

Armpits and groins Armpits and groins

Treatment history SA, anti-androgens,

prednisone,

etanercept, infliximab,

surgery

SA, i.l. Corticosteroids,

surgery

TA, SA SA, surgery SA, surgery

Current treatment infliximab 5 mg kg-2

every 4 weeks

i.l. Corticosteroids Doxycycline 100 mg

daily

None None

aMonozygotic twin sisters; bexcept for the monozygotic twin sister no other family members were affected. BMI, body mass index; HS,

hidradenitis suppurativa; i.l., intralesional; SA, systemic antibiotics; TA, topical antibiotics.

Table 1. Characteristics of the patients with Down syndrome

41

Figure 1. (a) Patient 1 with erythematous nodules, fistulae and scarring located on the genital area, before treatment

with infliximab. (b) Four months later after four infusions of infliximab; the hidradenitis suppurativa has improves to some

extent but there are still multiple active nodules and fistulae present.

Figure 2. (a) Normal situation: amyloid precursor protein (APP) and the Notch receptor are both processed by g-secretase

(GS). APP is cleaved by GS whereupon β-amyloid (Aβ) is released. The Notch receptor is also cleaved by GS leading

to the release of the nuclear intracellular domain (NICD). NICD enters the nucleus where it activates the transcription

factor for the Notch target genes that enhance epidermal differentiation and immune regulation. (b) patients with Down

syndrome: increased expression of APP changes the substrate pool of GS. Increased amounts of GS are required for APP

processing occurring at the expense of the Notch receptor. This leads to a “functional GS deficiency” for Notch processing

whereupon the release of the NICD is prevented resulting in impaired intracellular Notch signaling.

GS GS

Notchreceptor

Notchreceptor

NICD

NICD

NICD

NICD

NICD

extracellular

intracellular

Nucleus

NICD

extracellular

intracellular

Nucleus

Aβ

Aβ

Aβ

(a) (b)

(a) (b)

42

REfERENcES



Borbujo Martinez J, Bastos Amigo J, Olmos Carrasco O, et al. Suppurative hidradenitis in Down’s 2.

syndrome. Apropos of three cases. An Esp Pediatr 1992; 36:59-61.

Mebazaa A, Ben Hadid R, Cheikh Rouhou R, et al. Hidradenitis suppurativa: a disease with male 3.


Mengesha YM, Holcombe TC, Hansen RC. Prepubertal hidradenitis suppurativa: two case reports and 4.

review of the literature. Pediatr Dermatol 1999; 16:292-96.



Massi D, Panelos J. Notch signaling and the developing skin epidermis. 6. Adv Exp Med Biol

2012; 727:131-41.

Herzog V, Kirfel G, Siemes C, Schmitz A. Biological roles of APP in the epidermis. 7. Eur J Cell Biol

2004; 83:613-24.

Berezovska O, Jack C, Deng A, et al. Notch1 and amyloid precursor protein are competitive substrates 8.

for presenilin1-dependent gamma-secretase cleavage. J Biol Chem 2001; 276:30018-23.

Kusters MA, Verstegen RH, Gemen EF, de Vries E. Intrinsic defect of the immune system in children 9.

with Down syndrome: a review. Clin Exp Immunol 2009; 156:189-93.

43

45

4gENE ExPRESSIoN PRofILINg IN SKIN AND BLooD IN HIDRADENITIS SUPPURATIVA

J.L. Blok1, K. Li2; C. Brodmerkel2; B. Horváth1, M.F. Jonkman1

1. Department of Dermatology, University Medical Center Groningen, University of Groningen,

Groningen, the Netherlands 2. Janssen Research & Development, LLC, Spring House, PA, U.S.A.

Submitted

46

Hidradenitis suppurativa (HS) is an inflammatory skin disease characterized by recurrent

abscesses, nodules and sinus tract formation that is mainly localized in the body folds.

The pathogenesis of HS is poorly understood. Mutations in genes encoding for essential

compounds of the transmembrane protease g-secretase, including NCSTN, PSEN1 and PSENEN,

have been identified in familial HS.1,2 These mutations may result in impaired Notch signaling

promoting cyst formation and continuing inflammatory activity.3 Additionally, certain single

nucleotide polymorphisms (SNPs) at the promoter region of the tumour necrosis factor - alpha

(TNF-α) gene were found to be associated with a greater susceptibility for the development

of HS as well as to influence the natural course of the disease.4 Furthermore, elevated levels of

IL-1, TNF-α and IL-10 were demonstrated in both lesional and perilesional skin of HS patients,5

and increased expression of the IL-23/Th-17 pathway was found in lesional skin.6 However, the

mechanism behind these pro-inflammatory changes in HS is still largely unknown.

To acquire a better understanding of the molecular pathogenesis of HS, we performed mRNA

microarray studies to compare gene expression in lesional skin to healthy skin of HS patients.

Also, the gene expression profile in whole blood of patients and unaffected individuals was

determined.

Seventeen HS patients were included. Whole blood was collected from all subjects and ten

healthy controls. Skin biopsies of 3 mm were obtained from inflammatory lesions in all 17

patients. Additionally, an extra biopsy from clinically healthy skin of the upper arm or leg was

obtained from 13 patients. The skin samples were immediately frozen in liquid nitrogen and

subsequently stored at -80 degrees Celsius. mRNA was extracted from skin samples using the

Qiagen RNeasy Fibrous Tissue Mini Kit (Qiagen Inc., Valencia, CA) and from whole blood with

the Qiagen PAXgene blood RNA kit according to the manufacturer’s instructions. RNA was

hybridized to the GeneChip HT HG-U133+ PM Array (Affymetrix, Santa Clara, CA). Pathway

analyses were conducted with QIAGEN’s Ingenuity Pathway Analysis (IPA®, www.qiagen.com/

ingenuity). Array Studio software version 8.0 (OmicSoft Corp., St. Morrisville, NC) was used

to analyze microarray data. Dysregulated genes were identified using a general linear model.

Expression modulation with a fold change >2 or <-2 and an FDR-adjusted p-value < 0.05 were

considered significant.

A significant difference was observed in mRNA expression between lesional and clinically

healthy skin of HS patients, with over 1145 probe sets representing over 800 genes having

at least a two-fold change (p <0.05). Patients with the most dysregulated gene profile were

more likely to have longstanding disease (>15 years) (figure 1a). Pathway analyses of the

modulated genes were mostly related to inflammation, including cell adhesion, diapedesis and

47

extravasation as well as immune cell signaling and communication pathways (figure 1b). An

interesting finding is involvement of the atherosclerosis signaling pathway in lesional HS skin

as it supports the current thought that the inflammatory response in HS is associated with

metabolic syndrome.7 Expression of NCSTN, PSEN1 and PSENEN was not modulated in lesional

compared to clinically healthy skin of patients. No significant differences were identified in

whole blood mRNA expression between patients (N=17) and healthy controls (N=10) (data not

shown).

In summary, we demonstrated significant altered gene expression in lesional HS skin compared

to clinically healthy skin of patients. This, in addition to the finding that whole blood RNA

expression did not differ between HS patients and healthy subjects, implicates that activated

cells in HS reside in affected tissue. This may be due to migration of leucocytes from the

circulation into skin tissue in response to released inflammatory chemokines. Our results

implicate that the inflammatory reaction is restricted to the skin of specific anatomical areas

and HS may therefore be considered as a localized rather than a generalized skin disease.

However, our results must be interpreted with caution as the sample size was relatively

small. Regardless whether local dysregulation of the atherosclerotic pathway is caused by the

inflammatory process or a secondary event due to an unhealthy lifestyle, the clinician should

be aware of metabolic syndrome in HS patients as early detection and treatment may prevent

cardiovascular complications. As perilesional skin of HS patients already shows histological

abnormalities,8 one may hypothesize that the skin type of HS patients in general is genetically

different from normal human skin, making patients prone to the development of HS lesions

under certain mechanical and lifestyle triggers. Therefore, investigating differences in gene

expression between clinically healthy skin from predilection sites of HS patients and skin of

unaffected individuals from the same sites would be an interesting additional study.

48

Skin typeDisease duration

-3.00 3.00

5 15

0 2 4 6 8 10 12 14 16 18

- log (p-value)

Granulocyte Adhesion and Diapedesis

Agranulocyte Adhesion and Diapedesis

Atherosclerosis Signaling

Hepatic Fibrosis /Hepatic Stellate Cell Activation

Primary Immunodeficiency Signaling

Communication between Innate and Adaptive Immune Cells

Dendritic Cell Maturation

Complement System

Systemic Lupus Erythematosus Signaling

Leukocyte Extravasation Signaling

Non lesional Lesional

Figure 1. (a) The heat-map of differentially expressed genes in HS skin based on mRNA microarray analysis. A significant

difference was observed in mRNA expression between lesional (grey boxes) and non-lesional patient skin (red boxes).

Patients with the most dysregulated gene profile were more likely to have longstanding disease.

(b) The top ten canonical pathways involved in the disease profile of patient skin.

(a)

(b)

49

REfERENcES

Wang B, Yang W, Wen W, et al. Gamma-secretase gene mutations in familial acne inversa. 1. Science

2010; 330:1065.

Pink AE, Simpson MA, Brice GW, et al. PSENEN and NCSTN mutations in familial hidradenitis 2.

suppurativa (Acne Inversa). J Invest Dermatol 2011; 131:1568-70.



Savva A, Kanni T, Damoraki G, et al. Impact of Toll-like receptor-4 and tumour necrosis factor gene 4.

polymorphisms in patients with hidradenitis suppurativa. Br J Dermatol 2013; 168:311-17.






Gold DA, Reeder VJ, Mahan MG, Hamzavi IH. The prevalence of metabolic syndrome in patients with 7.


van der Zee HH, de Ruiter L, Boer J, et al. Alterations in leucocyte subsets and histomorphology in 8.

normal-appearing perilesional skin and early and chronic hidradenitis suppurativa lesions.

Br J Dermatol 2012; 166:98-106.

51

5SySTEMIc THERAPy wITH IMMUNoSUPPRESSIVE AgENTS AND RETINoIDS IN HIDRADENITIS SUPPURATIVA: A SYSTEMATIC REVIEW

J.L. Blok1, S. van Hattem1, M.F. Jonkman1, B.Horváth1

Department of Dermatology1, University of Groningen, University Medical Center Groningen,

Groningen, The Netherlands

Published in the British Journal of Dermatology, 2013;168:243-52

52

ABSTRAcTHidradenitis suppurativa (HS) is a difficult disease to treat. Although the pathogenesis of

this inflammatory skin disease is largely unknown, the important role of the immune system

has been demonstrated in both experimental and clinical studies. Clinicians are therefore

increasingly prescribing systemic treatments with immunosuppressive agents, but the more

traditional systemic retinoids, especially isotretinoin, also remain relatively common therapies.

In order to provide an overview of all currently available systemic immunosuppressive agents

and retinoids for the treatment of HS, a systematic search was performed using MEDLINE and

EMBASE databases. All published papers concerning systemic retinoids or immunosuppressive

treatment for HS in adults were included. The primary endpoint was the percentage of

significant responders, moderate responders and non-responders. Other endpoints were the

relapse rate and adverse events. In total 87 papers were included, comprising 518 patients

with HS who were treated with systemic retinoids, biologic agents or other immunosuppressive

agents including colchicine, ciclosporin, dapsone or methotrexate. The highest response rates

were observed with infliximab, adalimumab and acitretin. Overall, the quality of evidence was

low and differed between the agents, making direct comparisons difficult. However, based on

the amount of evidence, infliximab and adalimumab were the most effective agents. Acitretin

was also effective in HS, although the quality of the evidence was low. The therapeutic

effect of isotretinoin is questionable. Randomized controlled trials are needed to confirm the

effectiveness of acitretin as well as to identify the most effective immunosuppressive agent in

HS.

53

INTRoDUcTIoNHidradenitis suppurativa (HS), also known as acne inversa, is a chronic inflammatory skin

disease characterized by recurrent, painful, deep-seated nodules and abscesses. In an advanced

stadium sinus tracts are formed, eventually leading to fibrotic scars, dermal contractures and

induration of the skin.1,2 Lesions typically occur on inverse, apocrine gland-bearing skin, like

the axillary, inguinal and anogenital regions. Quality of life is greatly impaired in HS.3,4 In

addition to lifestyle changes, therapeutic options include topical and systemic antibiotics, anti-

androgens, systemic retinoids, immunosuppressive agents, laser treatment, and surgery.5-7

Since an effective monotherapy is lacking, it is often required to combine different treatment

modalities to achieve some improvement.

Although the pathogenesis of HS is largely unknown, follicular hyperkeratinisation followed

by follicular occlusion is a primary feature of HS.8-11 Several factors probably contribute to

these histological changes, including smoking, sweating, obesity and hormonal changes.12

The important role of the immune system in HS has been underlined in recent studies, where

several observations have been observed, including involvement of the interleukin (IL)-12/

Th1 IL-23/Th17 pathways, and increased TNF-α in the skin and serum.13-15 In addition, there

is a deficiency of IL-22 and IL-20 in lesional HS skin leading to decreased antimicrobial protein

(AMP) levels, making the skin prone to bacterial infection.16

In conclusion, both clinical and experimental studies support the use of anti-inflammatory

drugs and retinoids in the treatment of HS and several different types of these agents are

currently available. However, there is no consensus on which agent is most effective for HS.

Therefore, this review aims (i) to evaluate all existing evidence to date for the use of systemic

immunosuppressive agents and systemic retinoids in HS and (ii) to assess their current position

in the treatment of HS.

54

PATIENTS AND METHoDS Inclusion and exclusion criteria

Included in the study were all fully published papers that reported on the clinical effects of any

systemic immunosuppressive agents or systemic retinoids in HS localized at the typical inverse.

Patients had to be 18 years or older. Studies not exclusively dealing with HS were excluded,

unless data for HS could be extracted separately. Studies were excluded if insufficient details

were given on treatment regime in respect of dosing, treatment duration and concomitant

immunosuppressive medication. There were no language restrictions.

Types of outcome measures

The efficacy of treatment was classified for each patient as “significant response”, “moderate

response” or “nonresponse.” A significant response was defined as a reduction of the Sartorius

score with ≥50%, improvement in quality of life of >50% or if stated so by the authors. A

moderate response comprised score reductions <50% or if stated so by the authors. The

primary endpoint comprised the percentage of significant responders, moderate responders

and nonresponders. If a study did not report individual results, all patients of that study were

categorized corresponding to the reported mean results. Dropouts were considered to be

nonresponders. The secondary endpoint was the percentage of responders that relapsed during

or after discontinuation of treatment, and the tertiary endpoint comprised adverse events

(AEs).

Identification of studies

Databases were systematically searched by two independent authors (SvH and JLB) for studies

dated up to May 2012. A search was conducted using EMBASE (search terms: ‘hidradenitis

suppurativa’/exp OR ‘hidradenitis suppurativa’ OR (hidraden* AND suppurativ*) OR ‘acne

inversa’ OR ‘inverse acne’) and Medline (search terms: “Hidradenitis Suppurativa”[MeSH]

OR (hidraden* AND suppurativ*) OR “acne inversa” OR “inverse acne”). Reference lists of

included papers and relevant reviews were manually searched to identify additional papers.

Data extraction

Two authors (JLB and SvH) independently conducted data extraction by using standardized

forms. Discrepancies between the researchers were resolved through discussion. Authors were

not contacted for missing data. Data were analysed by means of descriptive statistics.

55

Quality assessment

The quality of evidence was assessed by grading as follows: A, systematic review or meta-

analysis, randomized controlled trial with consistent findings, or all-or-none observational

study; B, lower quality clinical trial or study with limitations and inconsistent findings, cohort

study or case-control study; C, consensus guidelines, usual practice, expert opinion, or case

series.17

56

RESULTSFigure 1 shows the process of study selection, at the end of which 87 papers were included,

comprising a total of 518 patients. The immunosuppressive therapies evaluated in these

papers were biologics, colchicine, ciclosporin, methotrexate and dapsone. Treatment with

systematic retinoids included the use of acitretin and isotretinoin. Two papers dealt with

two immunosuppressive agents and these studies are therefore discussed in subheadings

of the Results section.18,19 The level of evidence of included papers is described for each

immunosuppressive agent in Table 1. A summary of the results is described in Figure 2.

57

Figure 1. Study selection

58

Biologics Adalimumab

Studies: We identified 15 papers studying a total of 68 patients.18-32 One study had a

randomized double-blind placebo-controlled design (evidence level A).31 In one retrospective

cohort study, the effectiveness of adalimumab was compared to infliximab (evidence level

B).19 Four other studies had an evidence level of B,20,21,23,32 and the remaining 9 studies had

level C.18,22,24-30 Dosing regimes varied from 40-80 mg in a frequency ranging from weekly

to every other week. The treatment duration was ≥1 year in three studies,21,24,26 ≤6 months

in six studies18,20,22,27,31,32 and unclear in six studies.19,23,25,28-30 One patient was simultaneously

to adalimumab treated with methotrexate for the first 2 months.26 The follow-up time varied

between studies, ranging from 13 weeks-29 months.

Primary endpoints: in total, 30/68 patients (44%) showed a significant response to

adalimumab, 24 patients (35%) had a moderate response and 14 patients did not respond

(21%). (Figure 2)

Secondary endpoints: one paper reported that the majority of the seven responding patients

showed recurrence of HS after 1 year of follow-up; however, individual numbers could not be

extracted.19 Occurrence of relapse was described for 35 of the remaining 42 responders: 22/35

(66%) relapsed within 3-10 months after discontinuation of treatment.21,23,25,26,28,31 Seven of the

35 responders (20%) relapsed during treatment, but symptoms improved in all when the dose

of adalimumab was increased.23,26,28

Tertiary endpoints: Adverse events (AEs) are described in Table 2. Six papers did not report on

AEs.22,24,27-30,32

59

Immuno-suppressive agent

(total nr of papers)

Nr of level A evidence

(% within group)

Nr of level B evidence

(%within group)

Nr of level C evidence

(% within group)

% of responders

% of non responders

Biologicals 66 3 5 17a 24 48b 71

Adalimumab 15 1 7 5 33 9 60 79 21

Etanercept 9 1 11 5 56 3 33 56 44

Infliximab 42 1 2 7 17 34 81 89 11

Ustekinumab 2 2 100 75 25

Retinoids 13 6 46 7 54

Acitretin/etretinate 6 2 33 4 67 95 5

Isotretinoin 7 4 57 3 43 36 64

Other 8 2 25 6 75

Ciclosporin 3 3 100 100 0

Dapsone 3 3 100 100 44

Colchicine 1 1 100 75

Methotrexate 1 1 100 100

a one paper compared adalimumab with infliximab, and is included as level B for both adalimumab and infliximab.19

b One paper describes the efficacy of adalimumab and etanercept; therefore it has been included as level C for both adalimumab and

etanercept.18

Table 1. Level of evidence for all included studies

Etanercept

Studies: nine papers comprising 54 patients evaluated the effect of etanercept on HS.18,33-

40 One study had a randomized double-blind placebo controlled design (evidence level A);

however, after 12 weeks all patients received open-label etanercept.33 We included only those

10 patients who were initially allocated to etanercept group. Five papers had evidence level

B34,35,37,39,40 and 3 papers level C.(18,36,38) Dosing schedules varied from 25 mg to 50 mg once or

twice weekly to 100 mg weekly. Treatment duration was 3 months in two papers,34,35 6 months

in two33,39 and around 1 year or longer in four papers.18,36-38 The follow up time was 17-144

weeks. Long term results of the patients described by Giarmellos et al.35 were reported in a

separate paper.41

Primary endpoints: a significant response to etanercept was observed in 21/54 patients (39%),

whereas nine patients (17%) had moderate improvement and 24 patients (44%) did not

respond to the treatment. (Figure 2)

Secondary endpoints: in total 18/30 responders (60%) relapsed after treatment was

discontinued. The time to relapse ranged from immediately after stopping of treatment until 8

months thereafter, but the majority had recurrence of HS lesions within 2 months.

Tertiary endpoint: Table 2 describes the tertiary endpoints. One study did not report on AEs.18

60

Infliximab

Studies: the efficacy of infliximab was evaluated in 42 papers, comprising 147 patients.

One study had a randomized double-blind placebo controlled design (evidence level A) but

after 8 weeks all patients received infliximab.42 Only those 15 patients who were initially

allocated to infliximab were included. Evidence levels B and C were found in seven19,43-48

and 34 studies49-82 respectively. One study compared the effect of infliximab with another

treatment, namely adalimumab.19 Almost all 147 patients received intravenous infliximab

5 mg/kg at weeks 0, 2 and 6. In 10 studies treatment was discontinued after these three

administrations.19,46,57,61,63,65-67,70,82 However, the majority of patients received maintenance

therapy every 6-8 weeks. Dosing schedules were not clear in five papers.50,69,71,74,75 The duration

of treatment was >1 year in nine studies.45,48,49,53,56,60,64,79,80 In four papers patients, in addition to

infliximab, patients received methotrexate, which might have prevent the formation of auto-

antibodies.45,49,60,64 Simultaneously to infliximab, patients were treated with azathioprine in two

studies,70,72 prednisolone in one study,77 prednisolone and ciclosporin in one study,68 and with

oral azathioprine and methylprednisolone in one study.71

Primary endpoints: a significant improvement was seen in 74/147 patients (50%); 57 patients

(39%) showed moderate improvement and 16 patients (11%) had no response (Figure 2)

Secondary endpoints: Only 10/131 responders (8%) experienced recurrence of HS during

treatment,48,49,55,60,68,79 and 26 responders (20%) relapsed within 2 weeks to 3 years after

discontinuation of therapy.42,46,52-54,57,62,63,67,73,75 One paper reported that the majority of patients

had recurrence of HS one year after discontinuation of treatment, however, individual numbers

could not be extracted.19

Tertiary endpoints: Fourteen studies did not report on AEs.50,52,55,59-61,65,66,69-71,74,78,82 AEs were

observed in 19 studies (Table 2).19,42-48,57,63,64,68,72,73,75,76,79-81

Ustekinumab

Studies: Two papers comprising a total of four patients, evaluated the effect of ustekinumab

(both evidence level C).83,84 The patients received 45 mg ustekinumab at weeks 0, 4 and 12.

Subsequently, one patient received injections every 3 months,84 and three patients every 2

months.83 Three patients were treated for at least 6 months and two of them were probably

still on treatment at the time the paper was written.83

Primary endpoints: two of the four patients (50%) showed a significant response, one patient

had a moderate response (25%) and one patient (25%) did not respond. (Figure. 2)

Secondary endpoints: one responding patient had temporary relapses every 2 weeks prior to

61

his next injection, but after administration.84 In another responding patient lesions recurred

after 6 months.83 The dose ustekinumab was therefore increased to 90 mg and his disease has

improved ever since. The remaining one responding patient did not relapse during treatment.83

Tertiary endpoint: AEs were reported in one paper (Table 2).83

Retinoids

Isotretinoin

Studies: seven papers evaluated the effect of oral isotretinoin, and comprised a total of 174

patients. Level B evidence was found in four papers85-88 and level C in three.89-91 The daily

dosages of isotretinoin were 0.5-1.2 mg/kg and treatment duration was 4-12 months. One

patient was pretreated with prednisone and erythromycin, followed by the gradual introduction

of isotretinoin.89

Primary endpoints: significant improvement was observed in 32/174 patients (18%), moderate

improvement in 30/174 patients (17%) and no response was observed in 112 patients (64%)

(Figure 2).

Secondary endpoints: one study comprising 14 responders did not mention whether

recurrences occurred after cessation of therapy.85 Of the remaining 48 responders, six patients

(13%) relapsed within a couple of months after discontinuation of treatment.

Tertiary endpoint: Two studies did not report on AEs.85,89 All remaining 18 patients experienced

AEs (Table 2).

Acitretin and etretinate

Studies: Acitretin is a metabolite of etretinate and has replaced treatment with etretinate in a

variety of disorders, as it has a much shorter elimination half-life and is equally effective. Six

papers reported on the treatment of HS with these retinoids, and comprised 22 patients.92-97

The level of evidence was B in two studies;92,96 the remaining papers were level C. Patients

treated with etretinate received daily doses of 0.35-1.1 mg/kg and the daily doses for acitretin

ranged from 0.25-0.88 mg/kg. The duration of treatment was 3-39 months.

Primary endpoints: significant improvement was seen in 16 of 22 patients (73%), five patients

(23%) improved moderately and one patient (5%) did not respond to the therapy (Fig. 2).

Secondary endpoints: No relapses during therapy were described. Acitretin or etretinate

treatment was eventually discontinued in 17 patients. Within six months after cessation of

therapy, six of 17 patients (35%) had recurrence. Eight patients (47%) relapsed >1 year after

discontinuation of treatment.

62

Tertiary endpoint: The AEs that were reported are shown in table 2. Two studies did not report

on AEs.93,97 For one study, data on AEs could not be extracted separately for HS.96

other therapies Dapsone

Studies: the effect of dapsone was described in three papers all with evidence level C.98-100

In total 34 patients were treated with doses of 25-200 mg daily during 0.5-48 months. The

majority of patients was still on treatment at the time of study closure.

Primary endpoints: A significant improvement was seen in 12/34 patients (35%) showed a

significant response, seven patients (21%) had a moderate response and 15 patients (44%) did

not respond (Figure 2).

Secondary endpoints: Two studies reported that discontinuation of therapy led to a rapid

recurrence of HS lesions in all patients, and that dapsone treatment could therefore not be

terminated.99,100 Two out of nine responders in the study of Yazdanyar et al.98 also rapidly

relapsed after cessation of treatment; however, re-introduction of dapsone led to rapid

improvement.

Tertiary endpoint: Adverse events are shown in table 2.

Colchicin

Studies: we identified one paper (evidence level B) describing eight patients who were treated

with colchicine 0.5 mg twice daily during 4 months.101

Primary endpoints: Two out of eight patients (25%) had a moderate respons and six out of

eight patients (75%) did not respond to colchicines (Figure 2).

Secondary endpoints: these were not stated.

Tertiairy endpoint: The observed AEs are shown in Table 2.

Ciclosporin

Studies: we identified three papers (evidence level C) on ciclosporin.102-104 Four patients were

treated with ciclosporin 2-6 mg/kg daily for 4-15 months. Two patients were concomitantly

treated with prednisolone and oral antibiotics.102,103

Primary endpoints: a significant response was observed in two of four patients (50%) and the

remaining two patients had a moderate response (Figure 2).

63

Secondary endpoints: in one patient ciclosporin was discontinued after 4 months, leading to

a recurrence 4 months later.102 Two patients were still on treatment at the time the paper was

published and did not experience any relapses. It was not reported whether the last patient

experienced relapse.104

Tertiary endpoint: These were not reported in any of the studies.

Methotrexate

Studies: we identified one paper that reported on the effectiveness of methotrexate in HS.105

It concerned an open study in which two patients received a weekly dose of 12.5 mg and one

patient received 15 mg. Treatment duration was 6 weeks, 4 months or 6 months.

Primary endpoints: none of the three patients responded to the treatment with methotrexate

(Figure 2).

Secondary endpoints: since none of the patients showed a response to the treatment, time to

relapse was not applicable.

Tertiary endpoint: Adverse events were not reported.

64

SI = significant responders. M

I = m

oderate responders. NR

= non-responders. N

= num

ber of patients.

Figure 2. Overview

of total number of papers and treated patients for each agent, including response rates.

65

Immunosuppressive agent (number of treated patients)

Observed adverse events (frequency) Nr of patients that discontinued treatment due to adverse events

Adalimumab (68) Painful injection site,a mild infections (10), non-specific gastrointestinal symptoms

(3), non-specific rash (3), fatigue (3), elevated liver enzymes (2), reactivation of

Epstein-Barr virus (1), severe infusion reaction urticaria (1), facial cellulitis (1),

irritation ears (1), hoarseness (1), headache (1), dry eyes (1), muscle chest pain (1),

dry skin (1), hay fever (1),

1(23)

Etanercept (54) Injection site reaction,a upper respiratory tract infection (4), nausea (3), paresthesias

(2), chest pain (2), cellulitis (2), muscle cramps (1), flu-like symptoms (1),

hypertension (1), elevated cholesterol (1)

3 (34)

Infliximab (147) Non-specific side effects (14), headache (7), acute arthritis/myalgia (8),

hypersensitivity reactions (5), influenza-like illness (4), dizziness (3), asthenia

(3), numbness in legs/neuropathy (3), skin rash (3), anaphylactic shock (1),

pneumococcal sepdis (1), localized tuberculosis infection (1), pustular lesions lower

limbs (1), fever (1), hypertension (1), herpes zoster (1), colon cancer (1), cervical

abscess (1), dyspnoea (1), lupus like reaction (1)

31 (43-46,48,57,63,68,72,73,75,76,78-80)

Ustkeinumab (4) Cystitis (1), psoriasiform dermatitis (1), HS lesion infected by staphylococcus aureus

(1)

None

Isotretinoin (174) Cheilitis/xeorsis (15), usual side efectsb (3), arthralgia (1), headache (1) 10 (86)

Acitretin/etretinate

(22)

Cheilitis/xerosis (13), alterations in lipids (4), altered triglyceride levels (3),

hypertrichosis/photosensitivity (2), alopecia (2), depression/fatigue (1), headache (1),

loss of concentration (1), elevated cholesterol (2), buzzing ears (1), joint pain (1)

2 (92,95)

Dapsone (34) Anemia/hemolysis (4), nausea (3), dizziness (2), tiredness (2), headache (2), elevated

bilirubine (1), rash (1), gloomy mood (1), malaise (1)

None

Colchicine (4) Nausea (3), diarrhea (3) 1 (101)

Methotrexate (3) Adverse events not stated none

Ciclosporin (4) Adverse events not stated none

a some studies reported that this event occurred in 'several patients', without mentioning exact numbers.

b Probably xerosis/cheilitis

66

DISCUSSION To the best of our best knowledge, this is the first systematic review specifically aimed to

analyze all currently available evidence of immunosuppressive agents and systemic retinoids for

the treatment of HS. In total 518 patients were analysed, divided over 87 papers. The majority

of patients (n = 273) was treated with a biological agent. Overall, the quality of the included

papers was low; only three randomized controlled trials were identified, all on biologics.31,33,42

The majority of papers were case reports or series, bringing along a risk of publication bias.

Two papers were not identified by our search strategy due to the fact that they were not

incorporated in Medline or EMBASE.96,97

Based on our results, the most effective agents for HS were infliximab, adalimumab and

acitretin with respectively 89%, 79% and 96% of patients, respectively, responding to

treatment. However, as the results of acitretin were based on far fewer patients and were of a

lower level of evidence than the results for infliximab and adalimumab, caution must be taken

when directly comparing the efficacy of these agents. The positive results of infliximab and

adalimumab are in accordance with the findings of Van Rappard et al.106 Acitretin for HS is

barely mentioned in the literature, however, its positive effect is pharmacologically reasonable,

as the primary event in HS is follicular occlusion and acitretin induces normalization of the

epithelial cell proliferation and differentiation.107,108 Not surprisingly, isotretinoin is ineffective

for HS as this agent primarily works on sebaceous glands, which are not involved in the

pathogenesis of HS.109,110 The observation that 35% of treated patients still responded to

isotretinoin, is more likely to be due to the immunomodulatory effects of this retinoid.111

The highest quality of evidence was identified for etanercept, which enables us to conclude

that the efficacy (56% responders) was relatively low. Only a few patients have been treated

with ustekinumab, ciclosporin, dapsone, methotrexate and colchicine. It has been shown that

the IL-12/IL-23 pathway is upregulated in HS, therefore there is a rationale for the efficacy

of ustekinumab (an inhibitor of this pathway), and the first results of this agent are indeed

promising.83,84 However, clinical trials are needed to confirm its effect. The same applies for

ciclosporin; although all patients responded to treatment, this agent has been studied in only

four patients, making it impossible to draw any definite conclusions. The efficacy of dapsone is

doubtful, methotrexate as a monotherapy seems of little value and colchicine is not effective in

HS.

Although long-term results and relapse rates were not available for many papers on biologics,

recurrence of HS occurred frequently during therapy or within a couple of months after

cessation of biologic therapy. In contrast, Boer and Nazary92 achieved long-term remission (i.e.

>1 year) in a majority of patients treated with acitretin, indicating that this is probably also

67

effective on the long term. However, this observation needs to be confirmed in bigger trials

since only 12 patients were included.

Adverse events were observed with all agents, except for ciclosporin and methotrexate, where

it was not stated. The highest number of withdrawals due to AEs occurred with infliximab and

isotretinoin. Other reviews also showed that the risk of withdrawal is higher during infliximab

therapy compared with adalimumab and etanercept therapy.106,112 The most common AE

during acitretin therapy is cheilitis which can be very disturbing for patients. Moreover, the

most important disadvantage of acitretin is that it has extremely teratogenic side effects.113

Therefore, this agent should mainly be reserved for men and sterilized or postmenopausal

women.

A limitation of this review, and any other review on HS treatment, is heterogeneity between

the studies in respect of study design, number of included participants, the severity of HS and

the timing and methods for outcome assessments. Therefore, caution must be taken in directly

comparing the different treatment options of HS.

In conclusion, this review indicates that, based on the evidence today, infliximab and

adalimumab are the most effective immunosuppressive agents for HS. Additionally, acitretin is

a promising agent and definitely worth considering in men and sterilized or postmenopausal

women, although high quality evidence is lacking for its administration in HS. Also, these data

strongly indicate that there is a need for randomized controlled clinical trials in order to identify

the most effective treatment targets and the most effective therapy for HS.

68

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79

6USTEKINUMAB IN HIDRADENITIS SUPPURATIVA: A CLINICAL OPEN LABEL STUDY WITH ANALYSES

OF THE PROTEIN EXPRESSION PROFILE IN SERUM

Janine L. Blok, MD1; Katherine Li, MS2; Carrie Brodmerkel, PhD2; Péter Horvátovich PhD3,

Marcel F. Jonkman, MD PhD1; Barbara Horváth, MD PhD1

1Department of Dermatology, University Medical Center Groningen, University of Groningen,

Groningen, the Netherlands 2Janssen Research & Development, LLC, Spring House, PA, U.S.A. 3 Department of Pharmacy, Analytical Biochemistry, Faculty of Mathematics and Natural

Sciences, University of Groningen, Groningen, The Netherlands

Submitted

80

ABSTRAcTIntroduction

Treatment of hidradenitis suppurativa (HS) is difficult and the search for effective therapies

continues.

Objectives

To evaluate the efficacy of ustekinumab in HS.

To discover a potential biomarker.

Material and methods

Seventeen patients were included in this open label study and treated with 45 to 90 mg

ustekinumab at weeks 0, 4, 16 and 28. Proteomic technology and enzyme-linked assay

analysis (ELISA) was applied on serum.

Results

Twelve patients completed the protocol. Moderate to marked improvement of the modified

Sartorius Score was achieved in 82% of patients at week 40 and the hidradenitis suppurativa

clinical response (HiSCR-50) in 47%. There was significant modulation in the expression of 54

serum proteins in patients at baseline compared to normal controls. Involved pathways were

related to inflammation, immune cell signaling, and tissue morphology and development. Four

of these (FSH, LH, HCG and LTA4H) were significant modulated at the end of treatment. Good

responders had milder disease and lower expression of leukotriene A4-hydrolase (LTA4H). IL-

2R, TNF-α, IL17A and IL-17F were not elevated in patient serum and did not change during

treatment.

Conclusion

The majority of patients showed improvement with ustekinumab. Although no biomarker was

discovered, low LTA4H concentrations with mild disease severity may be predictive for the

effectiveness of ustekinumab.

81

INTRoDUcTIoN Hidradenitis suppurativa (HS) is an inflammatory skin disease characterized by recurrent

abscesses and sinus tract formation.1 The clinical severity of HS is commonly classified

according to the Hurley stages.2 HS is painful and disfiguring, impairing quality of life to a

great extent.3,4 Genetic susceptibility, smoking and obesity are important risk factors for the

development of HS.5

A dual approach is usually adopted in the treatment of HS. First, the inflammatory reaction

is inhibited with systemic anti-inflammatory or immunosuppressive agents. Lesions resistant

to systemic therapy, like sinus tracts, are subsequently surgically removed.6 Commonly used

immunosuppressive agents are tumor-necrosis-factor-α (TNF-α) inhibitors, like infliximab and

adalimumab.7 However, in a substantial number of patients TNF-α inhibitors are ineffective or

cause adverse events requiring discontinuation of therapy.7,8 Therefore, there is still a need for

new effective immunosuppressive agents in HS.

The pathogenesis of HS has not been clarified yet. It has been suggested that follicular

plugging followed by the release of follicular material into the dermis are primary events that

activate the immune system.9 Unraveling what cytokines are involved has been the main

objective of several studies. Recently, it has been shown that the interleukin-23/ T-helper 17

cells (IL-23/Th17) and IL-12/Th1 pathways come to expression in HS skin.10,11

Ustekinumab is a human IgG1k monoclonal antibody that binds with high affinity to the

p40 subunit of IL-12 and IL-23. Thereby, these cytokines are prevented from interacting

with their IL-12Rβ1 receptor protein that is expressed on the surface of T-cells and natural

killer cells.12 Certain genetic variations within the gene encoding for the common IL-12βR1

subunit of the IL-12/IL23 receptor have shown to be associated with a more severe course of

HS.13 Ustekinumab has been approved for the treatment of psoriasis.14-16 The effectiveness of

ustekinumab in HS has been retrospectively studied in a total of seven patients with conflicting

results.17-20 With this open label prospective study we investigated the efficacy and safety of

ustekinumab in a group of 20 patients with moderate to severe HS. To identify candidate

biomarkers for HS we performed proteomics and immunoassays on serum of patients and

healthy volunteers.

82

MATERIAL AND METHoDS The manuscript was approved by the institutional review board.

Study patients

Subjects were recruited from May 2012 until March 2013. Patients with moderate to severe

HS (Hurley stage II-III) with a treatment history of at least one systemic anti-inflammatory/

immunosuppressive agent or surgery were eligible for participation. The diagnosis of HS was

made by a dermatologist.

Design and intervention

The trial had a prospective uncontrolled open-label design. The washout period for systemic

immunosuppressive medication was at least 3 months. All patients received ustekinumab

according to the psoriasis dosing regimen.(14) Subcutaneous injections were administered at

weeks 0 and 4 (induction phase) and week 16 and 28 (maintenance phase). Each injection

contained 45 mg ustekinumab, with subjects weighing >100 kg receiving 90 mg per injection.

The intervention period was set to 40 weeks, consisting of the treatment phase (weeks 0-28)

followed by a post-treatment phase of 12 weeks. Topical resorcinol 15% cream or incision

and drainage of acutely painful were the only allowed escape treatments. Assessments were

performed by the same investigator at baseline (week 0) and weeks 4, 10, 16, 22, 28, 34

and 40. The study was approved by the local institutional review board and registered with

ClinicalTrials.gov (NCT01704534).

Assessments of disease severity

At every visit, the modified Sartorius scale (mSS) and modified hidradenitis suppurativa-lesion

area and severity index (mHSLASI) were assessed. The mSS is a dynamic scoring system

for HS and includes the number of involved anatomical regions, the type and number of

lesions, the extent of involvement and the Hurley stage.21 The mHSLASI reflects the degree of

inflammatory activity by assessing the level of experienced pain, redness, edema and lesional

discharge.22 A ≥50% reduction in these scores was considered as a marked response; 25-<50%

reduction as moderate; >0-<25% reduction as mild and ≤0 as non-response.

A visual analogue scale (VAS) to determine the degree of experienced pain ranging from 0

mm (no pain) to 100 mm (maximum pain), the Dermatology Life Quality Index (DLQI) and

Skindex-29 questionnaires were used to investigate patient-reported outcomes.

83

outcomes and follow-up

The primary endpoint was the proportion of patients with marked improvement (≥50%

reduction) of the mSS and mHSLASI scores at week 40. Secondary outcomes included the

mean change in patient’s reported pain, Skindex-29 and DLQI. Regarding the Skindex-29, the

cut-off scores as proposed by Prinsen et al.23 were applied. Improvement of the Skindex-29

was considered as clinically meaningful if the score of a specific domain went at least one scale

down compared to week 0. A DLQI of 0-1 corresponds to no effect on patient’s quality of life,

an index of 2-5 to a small effect, 6-10 to a moderate effect, 11-20 to a very large effect and

21-30 to an extremely large effect on patient’s quality of life.24 A reduction of ≥5 points on the

DLQI was considered as clinically meaningful improvement.25

We performed a post-hoc analysis using the Hidradenitis Suppurativa Clinical Response

(HiSCR), which is a recently validated endpoint for assessing HS treatment effectiveness.26

Responders (HiSCR achievers) are defined as patients with at least 50% reduction in the

number abscesses or inflammatory nodules, without an increase in draining fistulas (HiSCR-50).

This endpoint was added to support our clinical scores as the mSS and mHSLASI may not be

optimal in assessing inflammatory manifestations.27

Sample collection and analyses

Protein analyses from serum:

A total of 1129 proteins were measured in serum by somalogics (high content proteomics)

using “SOMAscan” (SomaLogic Inc. Boulder, CO) at baseline and at week 40.

Pathway analyses:

Pathway analyses were conducted with QIAGEN’s Ingenuity Pathway Analysis (IPA®, www.

qiagen.com/ingenuity).

Immunoassays: Enzyme-linked Immunosorbent Assay (ELISA) was performed on serum at baseline, week 4,

16, 28 and 40 for TNF-α (MesoScale Discovery, Rockville, MD) and the soluble IL-2 receptor

(sIL2R) (Alpco, Salem, NH) according to the manufacturer’s instructions. Serum IL17A and

IL17F were measured by the Erenna® Immunoassay system according to the manufacturer’s

84

instructions (Singulex, Alameda, CA). Based on the protein Somalogics data measured at

week 0 and 40, additional ELISA analyses were performed for leucotriene A4-hydrolase

(LTA4H), follicle stimulating hormone (FSH), luteinizing hormone (LH) and human chorionic

gonadotropin (HCG) at weeks 0, 4, 16 28 and 40.

Safety assessments

Serious adverse events were reported to the competent Health Authorities and the ethics

committee within 24 hours in addition to completion of a Suspected Unexpected Serious

Adverse Reaction form. A Data Safety Monitoring Board gathered every six months.

Statistical analysis

Descriptive statistics (mean, percentages, minimum and maximum) were performed for the

outcome variables. Efficacy analyses were conducted on the intention-to-treat (ITT) population

that included all patients who received at least one dose of study medication. If a patient

dropped out it was attempted to obtain further patient assessments for the primary outcomes,

if not the missing data were handled by carrying the last observation forward. The Wilcoxon

rank test was used to analyze the efficacy of treatment. The criterion for statistical significance

was p<0.05. Analyses were performed with SPSS Statistics 22.

Array Studio software version 8.0 (OmicSoft Corp., St. Morrisville, NC) was used to analyze

proteomics data. Blood samples from healthy volunteers were used as controls for serum

proteomics. Expression modulation was analyzed using a general linear model. A >1.5 fold

change and an FDR-adjusted p-value < 0.05 were considered significant. Scatter plots were

made with Matlab version 8.3.0.532 (R2014a).

85

RESULTSPatients and drop-outs

A total of 26 patients were screened for entering the study. Seventeen (four men, 13 women)

instead of the initially planned 20 patients were included, as the trial medication expired due to

a slower recruitment rate than expected. Patient’s characteristics are described in table 1. Five

subjects dropped out prematurely. The mean age was 35 years (range 20-53), mean BMI 28.3

kg/m2 and mean disease duration was 18 years.

Primary endpoints (mSS and mHSLASI)

At week 40 improvement of the mSS was marked in six of 17 patients (35%), moderate in

eight patients (47%), mild in one patient (6%) and in two patients (12%) there was no change

or worsening. The mean mSS of the ITT population significantly reduced from 112.12 at

baseline to 60.18 at week 40 (46.33% improvement; p=0.001) (fig. 1a).

Improvement of the mHSLASI at week 40 was marked in three of 17 patients (18%), moderate

in six patients (35%), mild in three patients (18%) and in five patients (29%) there was no

change or worsening. The mean mHSLASI of the ITT population significantly reduced from

26.29 at baseline to 19.59 at week 40 (25.5% improvement; p=0.011) (fig. 1a).

Secondary endpoints (Skindex-29, VAS, DLQI)

At week 40 clinically meaningful improvement on the Skindex-29 overall domain was

observed in six of 17 subjects (35%), on the functioning domain in eight subjects (47%), on

the emotions domain in four subjects (24%) and on the symptoms domain in three subjects

(18%) (fig. 1c). At baseline, the DLQI indicated that HS had a very large or extremely large

effect on daily life in 71% of subjects, at week 40 this was 59% (fig. 1d). At week 40 clinically

meaningful improvement of the DLQI had occurred in seven patients (41%). The mean

reported pain on a VAS was 5.8 out of 10 at the start of treatment and 4.6 at week 40.

Post-hoc analysis with HiScR

The number of HiSCR-50 achievers increased from the induction phase through to week 22. At

week 40, eight out of 17 patients (47%) were HiSCR50 achievers (fig. 1b).

86

Escape treatments

Resorcinol 15% cream was used for troublesome inflammatory lesions by four patients and

incision and drainage in one patient. The protocol was violated in two patients who received

intralesional corticosteroids for painful lesions that were not suitable for incision and drainage.

Safety assessments

The most common adverse events were headache, fatigue and upper respiratory tract

infections. All events were mild and temporary.

Protein expression in the serum

Fifty-four proteins were significantly differentially expressed in serum of patients (n=17)

at baseline compared to healthy controls (n=10) (fig. 2a). The top involved dysregulated

pathways were related to inflammation, immune cell signaling, as well as tissue morphology

and development (fig. 2b). Significant modulation of the leucotriene A4-hydrolase (LTA4H),

follicle stimulating hormone (FSH), luteizing hormone (LH) and human chorionic gonadotropin

(HCG) were identified at week 40 in the four best responders (subjects 6, 12, 14, 15).

Serum ELISA for LTA4H, fSH, LH and Hcg

As LTA4H, FSH, LH and HCG were identified as potential biomarkers with protein microarray

analysis, these were further analyzed with ELISA. No linear correlation between clinical disease

severity and serum concentrations was identified, making these proteins not suitable as

biomarkers for treatment effectiveness. However, good responders showed a trend towards

having a relatively less severe clinical phenotype as well as lower concentrations of LTA4H

(fig. 3).

Serum ELISA for sIL-2R, TNf-α, IL17A and IL-17f

There were no significant differences in serum concentrations of sIL-2R, TNF-α, IL17A and

IL-17F between patients and controls, nor did we identify a significant decrease in any of these

cytokines during ustekinumab treatment (data not shown).

87

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88

Figure 1. Clinical scores during ustekinumab treatment

(a) Percentual reduction of the mSS and mHSLASI during ustekinumab treatment.

(b) The number of patients achieving >50% improvement of HiSCR during ustekinumab treatment.

(c) Improvement in Skindex-29 occurred for each domain with worsening of the scores during the post-treatment phase.

(d) The impact of HS on daily life as measured by the DLQI. The number of patients is presented within the bars.

Arrows represent ustekinumab administration points

(a) (c)

(b) (d)

89

Natural Killer Cell Signaling

Fc Epsilon RI Signaling

Insulin Receptor

Ephrin Receptor

T Cell Receptor Signaling

HGF Signaling

Pancreatic Adenocarcinoma Signaling

Role of Tissue Factor in Cancer

Ovarian Cancer Signaling

PI3K Signaling in B Lymphocytes

0 1 2 3 4 5 6

- log (p-value)

Disease

-3.00 3.00

Controls HS patients

Figure 2. Disease profile in serum

(A) The heat-map of the HS disease profile in serum based on somalogics. The expression of 54 proteins was significantly

different between HS (red boxes) and healthy controls (grey boxes) at baseline.

(B) The top 10 involved canonical pathways in serum of HS patients.

90

Figure 3. Scatter plot for the correlation between LTA4H and the absolute HiSCR.

There is no linear correlation between the concentration of LTA4H and the HiSCR. Note that good responders (green

circle) have lower HiSCR combined with lower LTA4H concentrations compared to non-responders (red circle).

91

DIScUSSIoNThis is the first prospective study investigating the efficacy of ustekinumab in HS. Both

primary outcomes (mSS and mHSLASI) showed a significant reduction of the mean at week

40. Additionally, moderate to marked improvement of the mSS and mHSLASI was seen in

the majority (82% and 53% respectively) of patients. This suggests that ustekinumab may

be applied for the treatment of HS as the reduction in mSS is comparable to studies on

adalimumab and infliximab.8,28

The mSS reduced >50% in 35% of patients. Other studies considered reductions of 30% to

40% as therapeutic responses.29,30 The HiSCR-50 was achieved in 47%. Considering ≥50%

improvement of the mSS as clinically meaningful in HS is therefore probably too strict. The

psoriasis dosing regimen may not have been sufficient for HS, further explaining why only

a minority met the primary endpoint. Indeed, inflammatory marker levels are higher in HS

than in psoriasis.10 Increasing the administration frequency, as has been shown to improve the

results of adalimumab in HS, as well as increasing the dosage, which has been safely applied in

Crohn’s disease, may therefore improve the effectiveness of ustekinumab.8,31

Almost half of the patients showed clinically meaningful improvement on the functioning

domain of the Skindex-29 at week 40. Quality of life scores worsened at the post-treatment

phase, suggesting that longer treatment duration may lead to prolonged effectiveness.12

Upper respiratory tract infections were one of the most common adverse events. The

increased infection risk during ustekinumab treatment is caused by suppression of Th-17 cell

differentiation, as IL-17 provides immunity against microbes like staphylococcus and candida.

We could not confirm the potential of sIL2R as a serum biomarker in HS.32,33 Neither could

we put IL-17A, IL-17F and TNF-α forward as potential biomarkers. However, HS patients

had a significant different serum protein profile compared to controls, indicating that several

proteins are secreted towards the circulation by cells present in inflammatory skin. The

significant modulation in LH, FSH and HCG after treatment in the best responders, who were

all female, is difficult to interpret as these hormones naturally fluctuate during the menstrual

cycle. In psoriasis no correlation was found between disease severity and concentrations of

FSH and LH in male patients.34 However, estradiol concentrations were associated with milder

disease severity, confirming the potential protective role of estrogen in inflammatory diseases.

Therefore, the role of sex hormones in HS also remains an interesting topic for future studies.

We show significant modulation in the expression of LTA4H in the best ustekinumab

responders. LTA4H is an intracellular enzyme released by epithelial cells and macrophages.

It converts leukotriene A4 (LTA4) into leukotriene B4 (LTB4), a pro-inflammatory mediator

capable of recruiting and activating a wide range of immune cells, including neutrophils.

92

The subsequent LTA4H release from neutrophils counteracts the inflammatory reaction by

degradation of neutrophilic attractant peptides.35 This dual effect may be responsible for the

lack of a clear linear correlation between LTA4H serum concentration and clinical disease

severity. However, the LTA4H concentration in combination with disease severity (HiSCR) may

be used to predict the effect of ustekinumab: low concentrations with a relatively mild clinical

disease severity may be associated with a good response.

Limitations of this study include the small number of patients and the lack of a control group.

Furthermore, there was a relatively high dropout rate, increasing the risk of bias. This was

restricted to a minimum by analyzing the ITT population.

In summary, this study shows that ustekinumab is well tolerated and that the standard psoriasis

dosing schedule improved HS in the majority of patients. The dosing schedule may need to be

intensified for HS to achieve sufficient immune suppression. Modulated pathways in serum of

HS patients were related to inflammation, immune cell signaling, as well as tissue morphology

and development. A biomarker for measuring treatment effects in HS was not identified.

However, low LTA4H serum concentrations in combination with relatively mild disease severity

may be predictive for the efficacy of ustekinumab.

93

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study of 61 cases. J Am Acad Dermatol 2007; 56:621-23.



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Blok JL, van Hattem S, Jonkman MF, Horvath B. Systemic therapy with immunosuppressive agents 7.

and retinoids in hidradenitis suppurativa: a systematic review. Br J Dermatol 2013; 168:243-52.

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disorders. MAbs 2011; 3:535-45.

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Giatrakos S, Huse K, Kanni T, et al. Haplotypes of IL-12Rbeta1 impact on the clinical phenotype of 13.

hidradenitis suppurativa. Cytokine 2013; 62:297-301.

Leonardi CL, Kimball AB, Papp KA, et al. Efficacy and safety of ustekinumab, a human 14.

interleukin-12/23 monoclonal antibody, in patients with psoriasis: 76-week results from a randomised,

double-blind, placebo-controlled trial (PHOENIX 1). Lancet 2008; 371:1665-74.

Papp KA, Langley RG, Lebwohl M, et al. Efficacy and safety of ustekinumab, a human 15.

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Griffiths CE, Strober BE, van de Kerkhof P, et al. Comparison of ustekinumab and etanercept for 16.

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ustekinumab. Acta Derm Venereol 2012; 92:320-21.

Gulliver WP, Jemec GB, Baker KA. Experience with ustekinumab for the treatment of moderate to 18.

severe hidradenitis suppurativa. J Eur Acad Dermatol Venereol 2012; 26:911-14.

Baerveldt EM, Kappen JH, Thio HB, et al. Successful long-term triple disease control by ustekinumab 19.

in a patient with Behcet’s disease, psoriasis and hidradenitis suppurativa. Ann Rheum Dis

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Martin-Ezquerra G, Masferrer E, Masferrer-Niubo M, et al. Use of biological treatments in patients 20.

with hidradenitis suppurativa. J Eur Acad Dermatol Venereol 2015; 29:56-60.

Sartorius K, Emtestam L, Jemec GB, Lapins J. Objective scoring of hidradenitis suppurativa reflecting 21.

the role of tobacco smoking and obesity. Br J Dermatol 2009; 161:831-39.

Xu LY, Wright DR, Mahmoud BH, et al. Histopathologic study of hidradenitis suppurativa following 22.

long-pulsed 1064-nm Nd:YAG laser treatment. Arch Dermatol 2011; 147:21-28.

Prinsen CA, Lindeboom R, de Korte J. Interpretation of Skindex-29 scores: cutoffs for mild, moderate, 23.

and severe impairment of health-related quality of life. J Invest Dermatol 2011; 131:1945-47.

Hongbo Y, Thomas CL, Harrison MA, et al. Translating the science of quality of life into practice: 24.

What do dermatology life quality index scores mean? J Invest Dermatol 2005; 125:659-64.

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Basra MK, Fenech R, Gatt RM, et al. The Dermatology Life Quality Index 1994-2007: 25.

a comprehensive review of validation data and clinical results. Br J Dermatol 2008; 159:997-1035.

Kimball AB, Jemec GB, Yang M, et al. Assessing the validity, responsiveness and meaningfulness 26.

of the Hidradenitis Suppurativa Clinical Response (HiSCR) as the clinical endpoint for hidradenitis

suppurativa treatment. Br J Dermatol 2014; 171:1434-42.



van Rappard DC, Leenarts MF, Meijerink-van ‘t Oost L, Mekkes JR. Comparing treatment outcome of 28.

infliximab and adalimumab in patients with severe hidradenitis suppurativa. J Dermatolog Treat

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Savva A, Kanni T, Damoraki G, et al. Impact of Toll-like receptor-4 and tumour necrosis factor gene 29.

polymorphisms in patients with hidradenitis suppurativa. Br J Dermatol 2013; 168:311-17.

Fardet L, Dupuy A, Kerob D, et al. Infliximab for severe hidradenitis suppurativa: transient clinical 30.

efficacy in 7 consecutive patients. J Am Acad Dermatol 2007; 56:624-28.

Sandborn WJ, Gasink C, Gao LL, et al. Ustekinumab induction and maintenance therapy in refractory 31.

Crohn’s disease. N Engl J Med 2012; 367:1519-28.

Matusiak L, Bieniek A, Szepietowski JC. Soluble interleukin-2 receptor serum level is a useful marker 32.

of hidradenitis suppurativa clinical staging. Biomarkers 2009; 14:432-37.

Wieland CW, Vogl T, Ordelman A, et al. Myeloid marker S100A8/A9 and lymphocyte marker, soluble 33.

interleukin 2 receptor: biomarkers of hidradenitis suppurativa disease activity? Br J Dermatol

2013; 168:1252-58.

Cemil BC, Cengiz FP, Atas H, et al. Sex hormones in male psoriasis patients and their correlation with 34.

the Psoriasis Area and Severity Index. J Dermatol 2015; 42:500-03.

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Thorax 2011; 66:550-51.

97

7SKIN-TISSUE-SPARINg ExcISIoN wITH ELEcTRoSURgIcAL PEELINg (STEEP): A SURGICAL TREATMENT OPTION FOR SEVERE

HIDRADENITIS SUPPURATIVA HURLEY STAGE II/III

J.L. Blok1, MD; J.R. Spoo1, MD PhD; F.W.J. Leeman2, MD; M.F. Jonkman1, MD PhD; B.

Horváth1, MD PhD


Hanzeplein 1, 9700 RB Groningen, the Netherlands2Department of Dermatology, Antonius Hospital, 8601 ZK Sneek, The Netherlands

Published in the Journal European of the Academy of Dermatology and Venereology,

2015;29:379-82

98

ABSTRAcT Background: Surgery is the only curative treatment for removal of the persistent sinus tracts in

the skin that are characteristic of severe hidradenitis suppurativa (HS). Complete resection of

the affected tissue by wide excision is currently regarded as the preferred surgical technique in

these cases. However, relatively large amounts of healthy tissue are removed with this method

and suitable skin-tissue saving techniques aiming at creating less extensive surgical defects are

therefore needed in severe HS.

Method: We describe a skin-tissue saving surgical technique for HS Hurley stage II-III disease:

the Skin-tissue-sparing Excision with Electrosurgical Peeling (STEEP) procedure.

Discussion: In contrast to wide excisions that generally reach into the deep subcutaneous

fat, the fat is maximally spared with the STEEP procedure by performing successive tangential

excisions of lesional tissue until the epitheliazed bottom of the sinus tracts has been reached.

From here secondary intention healing can occur. In addition, fibrotic tissue is completely

removed in the same manner since this also serves as a source of recurrence. This tissue sparing

technique results in low recurrence rates, high patient satisfaction with relatively short healing

times and favorable cosmetic outcomes without contractures.

99

INTRoDUcTIoNHidradenitis suppurativa (HS) is an inflammatory skin disease characterized by painful deep-

seated nodules and abscesses that mainly occur on apocrine gland bearing skin.1 In a later

stage, sinus tracts surrounded by extensive fibrosis are formed in the dermis that in severe

cases even extend into the deep subcutaneous fat. These sinus tracts serve as a source for the

characteristic chronically recurring inflammation in HS. The Hurley classification is frequently

used to reflect disease severity by determination of: (i) the character of the lesions (solitary

nodules or abscesses correspond to stage I disease while stage II/III disease is characterized

by sinus tract formation); and (ii) the extensiveness of the lesions (differentiation of stage II

from stage III disease is made by determining whether or not there is healthy skin between the

lesions).2

Despite the numerous therapeutic options it is still difficult to treat HS, especially in severe

cases (Hurley stage II or III disease). Severe HS is characterized by both inflammation and a

permanent destruction of the normal skin architecture by the epithelialized sinus tracts and

fibrotic scars. Therefore, treatment requires a combined approach in order to be successful.

First, inflammatory activity needs to be improved. This can be achieved by systemic anti-

inflammatory or immunosuppressive treatment. However, (non-inflammatory) sinus tracts and

fibrotic scars will remain present after systemic therapy. The only way to permanently remove

these sinus tracts and fibrotic tissue is by means of surgery.

Currently, the classic deroofing technique and wide excision are regarded as the preferred

surgical methods for treating HS Hurley stage I/II and stage II/III respectively.3,4 However,

Hurley stage II/III disease remains a surgical challenge and the surgical treatment has dual

aspects. On the one hand, the goal of surgery is to achieve complete removal of lesional tissue.

On the other hand, it is important to spare as much healthy tissue as possible to prevent the

formation of serious contractures and to promote wound healing. The latter is not achieved

with wide excision. To meet both goals to a maximum we have developed a surgical technique

for severe HS where the advantages of both wide excision and the deroofing technique are

combined: the Skin-Tissue-sparing Excision with Electrosurgical Peeling (STEEP) procedure.

100

TEcHNIQUEThe STEEP procedure is performed under general anesthesia. The procedure starts with

palpation of the affected area to localize inflammatory nodules and fibrosis. Visible sinus

tracts are then sondaged with a probe to investigate their extensiveness. The sinus roof is

subsequently electrosurgically incised with a wire loop tip coupled to an Erbotoom (Erbe

USA Inc. Surgical Systems). This method is similar to the deroofing technique as described

previously for Hurley stage I/II disease.(3,4) Subsequently all lesional tissue, including fibrosis

that is identified by palpation, is removed from the incision on to the deeper skin layers by

successive tangential electrosurgical transsections (figure 1). The epithelialized sinus floors

and subcutaneous fat are left intact where possible. This procedure of incising sinuses and

tangential peeling off affected tissue is continued until the whole area is clear of lesional

tissue and fibrosis. Finally, the wound margins are meticulously checked with a probe for

the presence and removal of any residual sinus tracts. Hemostasis is achieved by using the

coagulation mode of the Erbotoom. The wound margins (i.e. healthy tissue) are injected with

triamcinolonacetonide 10-20mg and bupivacaine 0.5%(10ml) to prevent hypergranulation.

Wounds are left open to heal by secondary intention. Post-operative wound care consists

of twice daily irrigation followed by alginate and silicone dressings. Pain is managed with

acetaminophen, non-steroidal anti-inflammatory drugs or, in severe cases, opiates. Generally,

patients can leave the hospital on the day of surgery.

Figure 2 illustrates an example of the satisfying cosmetic results we achieve with the STEEP

procedure. This 46-year old woman with severe therapy resistant HS in the genital area was

initially treated with intravenous infliximab for six months. After five infusions, inflammatory

activity had improved and the STEEP procedure was then successfully performed in two

separate sessions. Currently (i.e. three years later), the disease is still in remission. Additionally,

her quality of life has significantly improved, as reflected in a reduction of her Dermatology Life

Quality Index (DLQI) from 28 points (maximum: 30) at the beginning of infliximab treatment

to 3 points at eight months after the final STEEP procedure.

101

Figure 1. Wide excision (a): red dotted line represents the cutting surface. Healthy tissue is removed and resection reaches

into the subcutaneous fat. STEEP-procedure (b): inflammatory nodules, sinus tracts and scar tissue are localized by a

probe or with palpation. Affected tissue is then peeled off layer by layer by means of multiple tangential transsections (red

dashed lines). The epithelial lining is spared in non-inflammatory sinus tracts but is totally excised in inflammatory sinus

tracts (blue dashed lines). The procedure is repeated until a plane has been obtained that is free of lesional tissue. The

result is that the final defect is smaller compared to wide excision.

Figure 2. Right groin before treatment with the STEEP procedure. Sondage with a tissue forceps demonstrates the depth

of the sinus tract (a). The right groin 24 weeks after the STEEP procedure (b).

Epidermis

Subcutaneous fat

Dermis

Sinus tract (non-inflammatory) Inflammatory nodule

(a) (b)

(a) (b)

102

DIScUSSIoNTreatment of HS is a challenge for both physicians and patients due to its complex and largely

unknown pathogenesis. It is generally accepted that in order to achieve satisfying results in

severe cases (Hurley stage II/III disease), a dual therapeutic approach is required.5 Usually, the

first step is inhibition of inflammatory activity with anti-inflammatory or immunosuppressive

agents, including infliximab.5,6 However, systemic treatment will not restore the skin’s

original architecture, meaning that epithelialized cysts and sinus tracts will remain present

in the affected skin once the inflammation has been treated. This may facilitate access for

(commensal) bacteria, leading to repetitive inflammation and further extension of the disease,

with ever-increasing architectural destruction.7 This vicious circle can only be interrupted by

surgical removal of these residual lesions.

The STEEP procedure is a promising tissue-saving surgical technique for HS Hurley stage II/III.

Tissue-saving surgical techniques are importance to HS for two main reasons: (i), HS especially

occurs in the body folds, which are areas prone to the formation of contractures after surgery

and (ii) large interconnected skin areas are frequently involved, making it even more important

to reduce the size of the already large surgical defects to a minimum. A suitable tissue-saving

surgical technique for Hurley stage I or limited stage II disease is the deroofing technique.3,4

However, in case of extensive Hurley stage II/III disease dominated by fibrotic tissue, the

deroofing technique is ineffective since fibrosis is not removed. Removal of fibrotic tissue is

important because it may contain skin appendages that serve as a source for recurrence and

also prevent adequate wound contraction and subsequent healing. In addition, the deroofing

technique is too time-consuming in severe HS. Surgical intervention by means of wide excision

is therefore often considered as the most effective treatment in these cases.8 However, the

STEEP procedure has several advantages over both wide excision and the deroofing technique

in severe HS. First, wide excisions always reach into the healthy deep subcutaneous fat, while

the STEEP procedure with its successive tangential transsections leaves the epithelialized

bottoms of the sinus tracts and a large extent of the subcutaneous fat intact, leading to more

superficial and smaller defects (fig 2). This results in relatively shorter healing times and fewer

complications, such as contracture formation. Furthermore, recurrence rates around the

operated area are reduced to a minimum since at the end of the STEEP procedure residual

affected tissue is identified and removed by sondaging the final wound margins with a probe

and extensive palpation. Tissue-sparing surgery in HS can also be accomplished with the use

of a CO2 laser, as previously demonstrated.9-13 The main advantage of CO2 laser incision is that

proper hemostasis is achieved allowing adequate visualization of remaining lesional tissue.

During the STEEP procedure prompt cauterization of bleeding vessels can be easily achieved

103

as well by switching between the surgery and electrocautery mode of the electrosurgical unit

using a foot pedal. For the performance of multiple transversal sections as we describe for our

surgical technique, electrosurgery has some important advantages over CO2 laser, namely:

(i) the depth of vertical incisions with transversal electrosection is more easily controlled and

adjusted by the surgeon. This leaves the epithelialized sinus bottom intact and warrants deep

excision of fibrotic and inflammatory tissue at the same time while a CO2 laser removes a

continuous horizontal plane of one depth, making it less precise and less tissue-sparing; (ii)

laser treatment is more expensive in terms of purchasing the device, the need for a special

room to perform the treatment and safety notices; and (iii) a basically trained dermatosurgeon

can perform electrosurgery, while laser treatment requires more experience and skills.

In our clinic, we have performed the STEEP procedure under general anesthesia in 156

patients with Hurley stage II/III disease between 2004 and 2013. The feedback from the

patients is generally very positive. Patients with extensive disease at multiple locations were

usually operated in several sessions. The wounds are allowed to heal by secondary intention

since in our experience, and that of others, it is time-efficient and leads to good cosmetic and

functional results.14,15 Furthermore, it allows prolonged wound drainage, diminishing the risk of

wound infection.14

In conclusion, we consider the STEEP procedure with electrosurgery superior over wide

resections and deroofing in Hurley stage II/III disease for several reasons: (i) recurrence rates

are low as it specifically aims at complete removal of lesional and fibrotic tissue; (ii) it saves

healthy tissue to a maximum which leads to rapid healing, satisfying cosmetic results and

prevention of contractures; (iii) healing time is further improved by allowing re-epithelization

of the defects from the intact epitheliazed sinus floors and dermal tissue where possible

rather than from subcutaneous fat; and (iv) in contrast to laser surgery the procedure can be

performed by basically trained dermatologic surgeons.

104

REfERENcES



pemphigus: surgical approach. In: Dermatologic Surgery (Roenigh R.K, Roenigh HH,eds). New York:

Marcel Dekker, 1989; 729-39.

Van der Zee HH, Prens EP, Boer J. Deroofing: a tissue-saving surgical technique for the treatment of 3.

mild to moderate hidradenitis suppurativa lesions. J Am Acad Dermatol 2010; 63:475-80.

van Hattem S, Spoo JR, Horvath B, Jonkman MF, Leeman FW. Surgical treatment of sinuses by 4.

deroofing in hidradenitis suppurativa. Dermatol Surg 2012; 38:494-97.

Van Rappard DC, Mekkes JR. Treatment of severe hidradenitis suppurativa with infliximab in 5.

combination with surgical interventions. Br J Dermatol 2012; 167:206-8.

Blok JL, van Hattem S, Jonkman MF, Horvath B. Systemic therapy with immunosuppressive agents 6.

and retinoids in hidradenitis suppurativa: a systematic review. Br J Dermatol 2013; 168:243-52.





Jain V, Jain A. Use of lasers for the management of refractory cases of hidradenitis suppurativa and 9.

pilonidal sinus. J Cutan Aesthet Surg 2012; 5:190-92.

Lapins J, Marcusson JA, Emtestam L. Surgical treatment of chronic hidradenitis suppurativa: CO2 laser 10.

stripping-secondary intention technique. Br J Dermatol 1994; 131:551-56.

Madan V, Hindle E, Hussain W, August PJ. Outcomes of treatment of nine cases of recalcitrant severe 11.

hidradenitis suppurativa with carbon dioxide laser. Br J Dermatol 2008; 159:1309-14.

Hazen PG, Hazen BP. Hidradenitis suppurativa: successful treatment using carbon dioxide laser 12.

excision and marsupialization. Dermatol Surg 2010; 36:208-13.

Bratschi HU, Altermatt HJ, Dreher E. Therapy of suppurative hidradenitis using the CO2-laser. Case 13.

report and literature review. Schweiz Rundsch Med Prax 1993; 82:941-45.

105

Bieniek A, Matusiak L, Chlebicka I, Szepietowski JC. Secondary intention healing in skin surgery: our 14.

own experience and expanded indications in hidradenitis suppurativa, rhinophyma and

non-melanoma skin cancers. J Eur Acad Dermatol Venereol 2013; 27:1015-21.

Wollina U, Tilp M, Meseg A, Schonlebe J, Heinig B, Nowak A. Management of severe anogenital acne 15.

inversa (hidradenitis suppurativa). Dermatol Surg 2012; 38:110-17.

107

8SURgERy UNDER gENERAL ANESTHESIA IN SEVERE HIDRADENITIS SUPPURATIVA: A STUDY OF 363 PRIMARY OPERATIONS IN 113

PATIENTS

J.L. Blok, MD1; M. Boersma, MD1; J.B. Terra, MD PhD1; J.R. Spoo, MD PhD1; F.W.J. Leeman,

MD2; E.R. van den Heuvel, MD PhD3; J. Huizinga, MSc, RN1; M.F. Jonkman, MD PhD1; B.

Horváth, MD PhD1


Hanzeplein 1, 9700 RB Groningen, the Netherlands 2Department of Dermatology, Antonius Hospital, 8601 ZK Sneek, The Netherlands 3Department of Epidemiology, University of Groningen, University Medical Center Groningen,

Hanzeplein 1, 9700 RB Groningen, the Netherlands

Published in the Journal of the European Acadamy of Dermatology and Venereology,

2015 doi: 10.1111/jdv.12952

108

ABSTRAcT Background: Treatment of hidradenitis suppurativa (HS) is a difficult undertaking, especially

since there is no consensus on what surgical technique is preferred. At our center severe HS

(Hurley II/III) is operated under general anesthesia, mostly with the STEEP-procedure.

Objectives: To investigate characteristics, surgical outcomes and patient satisfaction of HS

patients who underwent deroofing or STEEP under general anaesthesia.

Methods: A clinical records-based retrospective analysis was conducted of all patients who

had surgery under general anesthesia between 1999 and 2013. Patient satisfaction was

retrospectively investigated with questionnaires.

Results: A total of 482 operations (363 primary operations and 119 re-operations) was

performed during the study period. The proportion of women in the included population

was 68%. The median diagnostic delay (patient’s and doctor’s delay) was 6.5 years. Relapses

occurred after 29.2% of primary operations. Women had higher relapse rates than men (odds

ratio 2.85 [1.07;7.61]). Hypergranulation of the wound was the most common complication

and occurred in 7% of all operations. The median score patients attributed to the medical

effect of surgery was 8 out of 10 (zero corresponding to very dissatisfied and 10 to very

satisfied).

Conclusion: The diagnostic delay in HS is long due to a lack of knowledge in both patients

and health care professionals, indicating that there is a need for education. Deroofing and

the STEEP are effective surgical procedures in severe cases of HS and lead to a relatively high

patient satisfaction. The post-operative relapse risk is higher in women. Prospective studies are

required for the development of clear guidelines on the appropriate choice of surgery.

109

INTRoDUcTIoN Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with varying phenotypes.

The clinical severity is often classified according to the Hurley stages.1 Stage I is characterized

by abscesses and nodules while in stage II and III sinus tracts have been formed. The presence

of healthy skin between the lesions differentiates Hurley stage II from III disease. Several

treatment modalities are available for HS and usually a combination of different treatment

modalities is required. An effective topical treatment is resorcinol 15%.2 However, severe cases

require systemic and surgical treatment. Systemic treatment options include acitretin, antibiotics

and tumour-necrosis-factor-α (TNF-α)-inhibitors.3-6 Though these systemic agents may be able

to improve the inflammatory component, the architectural skin destructions that may have

been formed as a consequence of HS remain. Therefore, surgery is mandatory in the treatment

of severe HS.

There is no consensus on the most suitable surgical technique for HS. Optional methods

are (i) treatment of each individual lesion with deroofing,7,8 carbon dioxide laser treatment

or excision;9 (ii) radical excision of the entire affected area with wide margins;10 and (iii)

excision of the entire area encompassing all lesions with the “skin-tissue-saving excision with

electrosurgical peeling” (STEEP) technique;11 A detailed description of the STEEP technique

was recently published by our group.11 In short, the STEEP aims at removing all lesional tissue

by performing subsequent tangential transections (fig. 1, chapter 7). In contrast to wide

excision, which serves the same goal, the STEEP technique saves healthy tissue to a maximum.

Regardless of the applied surgical technique, wound closure for HS may be achieved with

sutures, skin grafts or flaps, or by secondary intention.12 Surgery is performed under local or

general anesthesia, a choice usually depending on the extensiveness of HS.

At our specialized day care center, we are able to perform surgery in HS patients under general

anesthesia. The use of general anesthesia enables us to treat large surface areas without

being limited by the maximum allowed amount of local anesthetics. There is an indication for

the STEEP procedure when patients have extensive stage II or III disease. In these cases the

deroofing technique is too superficial and therefore not sufficient as fibrotic scar tissue that may

serve as a source of relapsing disease, is not being removed. When patients with Hurley stage

I or limited stage II disease refuse to be operated with the deroofing technique under local

anesthesia, general anesthesia is also applied. In both, the STEEP and the deroofing technique

the wounds heal by secondary intention.

In this retrospective study we describe the characteristics of HS patients who underwent

deroofing or the STEEP-procedure under general anesthesia. Furthermore, we evaluate the

characteristics, outcomes and patient satisfaction regarding these treatments.

110

MATERIAL AND METHoDS Study design and subjects

The medical charts of all patients who underwent surgical treatment under general anesthesia

between May 1999 and January 2013 at our day care center were retrospectively analyzed by

two authors (J.L.B and M.B). Our day care center applies strict criteria regarding body mass

index (BMI): patients with a BMI ≥35 kg/m2 are refused for operation. The data were stored in

a database (SPSS Statistics 20 IBM, Armonk, New York, USA). The authors randomly checked

each other’s data extraction.

Primary parameters:

Characteristics of patients and surgeries

Patients’ characteristics included gender, age, smoking status, BMI and family history. Disease

severity was defined as the Hurley stage at the first visit to our department. Diagnostic history

included the diagnostic delay (sum of patient’s and doctor’s delay) and the number of visited

doctors before referral to our specialized center was achieved. The use of co-medication for HS

was only recorded if it had been used ≥2 months post-operatively.

Secondary parameters:

Surgical outcomes

These included the percentage of remissions, post-operative general disease activity, relapses

due to irradical surgery, natural disease progression and complications. Surgeries were divided

into primary operations and re-operations. Primary operations were surgeries performed for

the first time in a specific anatomical area. Any subsequent surgical procedures within that

anatomical area were defined as re-operations. General disease activity was defined as post-

operative inflammatory activity (abscesses, nodules or fistulas) occurring within the operated

anatomical area after a primary operation and was further subdivided into relapses due to

irradical surgery and natural progression of the disease. Relapses due to irradical surgery were

defined as inflammatory activity occurring within or at the border of the surgical scar and

considered unknown when the post-operative follow-up period was <8 weeks. Inflammation

in the operated anatomical area occurring outside the surgical scar was considered as natural

disease progression. Complications were recorded for all surgeries, including re-operations.

111

Factors influencing the risk of relapse

It was investigated whether disease location, gender, age, smoking status, BMI, and the use of

co-medication were associated with the occurrence of relapses.

Tertiary parameters:

Patient reported outcomes

Patients’ opinion about their surgical treatment was assessed with questionnaires. Patients who

were <18 years, mentally retarded or deceased were excluded. Patients were asked to name

the best treatment they ever had for HS and to rate their satisfaction regarding the cosmetic

and medical outcomes of the surgery on a scale from 0 (very dissatisfied) to 10 (very satisfied).

Medical ethical committee

In the Netherlands, retrospective studies of patient records and short questionnaires do not

need to be reviewed by a medical ethical committee.

Statistical analysis

Patients’ and surgical characteristics and outcomes were analyzed with descriptive statistics.

The chi-square test was used to compare differences between groups. A p-value <0.05 was

considered significant. A generalized linear mixed model (GLMM) was selected to investigate

whether the aforementioned variables influenced the relapse risk. A logit link function and a

random intercept were applied to address for repeated measurements in subjects (in multiple

subjects >1 anatomical area was operated). First, the variables were individually put into the

model. If the P-value of the fixed effect or the interaction effect with disease location was

below 0.25, the variable was selected for a multivariable model. In the second part of the

analysis a multivariable model was created containing all variables including their interaction

with location. Backward elimination was applied at the significance level of 0.05. The least

significant terms were eliminated one by one, keeping the model hierarchical. The analyses

were conducted with the procedure GLIMMIX of SAS institute.

112

RESULTS Primary outcomes

Characteristics of patients and surgeries

We included 113 HS patients in this study (male: female ratio = 1:2.1) (Table 1). Hurley stage

I disease was present in 11.5% of patients, stage II in 77.9% and stage III in 10.6%. In 23

patients the first symptoms appeared at the age of 16 years or younger and in five patients

before the age of 11. The median diagnostic delay was 6.5 years. On average, patients had

seen 2.35 doctors before they were referred to our specialized center and in 27.4% an accurate

diagnosis of HS had not been made until then. The median time between disease onset and

surgery under general anesthesia was 12.0 years (IQR seven-18 years). The groins and armpits

were affected in 85.8% and 62.8% of patients respectively (table 2). The buttocks were

significantly more often involved in men compared to women (69.4% vs. 41.6% respectively,

P=0.008). The main indication for general anesthesia was the extensiveness of disease

(64.6%), followed by request of the patient (30.1%), mental retardation since consciousness

during surgery may be traumatic for these patients and might hinder the procedure (2.7%) and

location of the disease (2.7%).

Secondary parameters

Surgical outcomes

A total of 482 regions were operated under general anesthesia in 113 patients (363 primary

operations and 119 re-operations). The mean number of locations treated within a single

surgical procedure was 2.4. Most primary operations were performed in the groins (40.5%),

followed by the armpits (22.9%), buttocks (19.8%) and genital area (10.2%) (table 3).

Complications developed in 16% of the 482 operations with the highest percentage occurring

in the armpits (33.7%). Hypergranulation of the wound was the most common complication

and occurred in 7.2% of all operations, followed by wound infections and post-operative

bleeding which both occurred in 1.8% of operations. Remission at the operated anatomical

area was achieved in 132 of 363 primary operations (Fig. 2). Disease activity at the operated

anatomical area eventually developed after 230 of 363 primary operations of which 124 were

considered as natural disease progression and 106 as true relapses due to irradical surgery.

113

Factors influencing the risk of relapse

For the first screening the variables “disease location” (P = 0.113), “gender” (P = 0.037)

and “smoking” (P = 0.141) were selected for the multivariable model (GLMM). The second

screening for variables investigating a possible interaction effect with location, indicated

that both gender (P = 0.111) and smoking (P = 0.061) should be selected. After backward

elimination the final model only contained the variable “gender” (P = 0.0369). The odds ratio

[95% CI] for gender was 2.85 [1.07; 7.61], indicating that women have a significant higher

risk of relapses after surgery.

Tertiary outcomes

Patient satisfaction

The questionnaire was sent to 105 of 113 patients. Home addresses were missing in three

patients, three patients had been deceased and two patients were mentally retarded. A total

of 66 of 105 patients responded. There were no significant differences between responders

and non-responders with respect to gender (P = 0.93) and relapses due to irradical surgery

(p=0.42). Surgery under general anesthesia was the best treatment for HS according to 76%

of responders. The median satisfaction scores for the medical and cosmetic effects of surgery

were, respectively, 8.0 and 6.0 out of 10.

114

n %

Sex Men 36 31.9

Women 77 68.1

Smoking status Never smoked 13 12.5

Missing: 3 Current/former smoker 91 87.5

BMI (kg/m2) Normal weight (≤24) 46 41.8

Missing: 3 Overweight (>24-29) 36 32.7

Obesity (≥30) 28 25.5

Hurely stage I 13 11.5

II 88 77.9

III 12 10.6

Age at onset of disease Mean (SD) 23.1 (8.2)

Missing: 6 ≤16 years 22 20.6

>16-39 years 81 75.7

≥40 years 4 3.7

Previously visited doctors Mean number of visited doctors (range)* 2.35 (0-7)

Missing: 50 Specialist who made diagnosis:

-General practitioner 12 19

-Dermatologist 43 68.3

-Surgeon 5 7.9

-Gastroenterologist 1 1.6

-Other 2 3.2

Median diagnostic delay in years (IQR**)

Missing: 59

6.5 (2.8-13.5)

Median time between disease onset and surgery under general anesthesia in years (IQR***)

Missing: 6

12.0 (7.0-18.0)

Previous treatments Incision/drainage 63 55.8

Wide excision 33 29.2

Deroofing under local anesthesia 28 24.8

Systemic antibiotics 110 97.3

Isotretinoin 22 19.5

Biologicals 7 7.2

*Before referral to our centre; **Standard deviation; ***Interquartile range

Table 1. Patient characteristics

115

Location Total, n=113 Men, n=36 Women, n=77 P-value1

n % n % n %

Armpits 71 62.8 26 72.2 45 58.4 0.210

Groins 97 85.8 28 77.8 70 90.9 0.074

Genital area2 57 50.4 21 58.3 37 48.1 0.322

Buttocks 57 50.4 25 69.4 32 41.6 0.008*

Submammary area 16 14.2 - - 16 28.6 -

Abdominal fold 14 12.4 8 22.2 6 7.8 0.062

Retroauricular/neck 9 8.0 5 13.9 4 5.2 0.141

Other areas3 29 25.7 16 44.4 13 16.9 0.003*

1Chi-square test; 2mons pubis, scrotum or labia; 3cheeks (n=1), upper legs (n=14), chest (n=5), underneath stoma pouch (n=1), popliteal

space (n=3), back (n=2) rump bone (n=5)

*Significant difference

Table 2. Affected locations

116

Armpits Groins Genital area Buttocks Other areas* Total

Number of operations

Primary operations 83 147 37 72 24 363

Re-operations 15 58 14 30 2 119

Total 98 205 51 102 26 482

Hurley stage, n (% of primary operations)

I 12 (14.5) 19 (12.9) 11 29.7) 25 (34.7) 11 (45.8) 78 (21.4)

II/III 71 (85.5) 126 (85.7) 22 (9.4) 44 (61.1) 13 (54.2) 276 (76.0)

Unknown - 2 (1.4) 4 (10.8) 3 (4.2) - 9 (2.5)

Co-medication, n

Tetracyclines 12 34 9 22 4 81

Clindamycine/rifampicin - - - - - -

Erythromycin - 4 2 2 1 9

Other antibiotics - 2 2 - - 4

Steroids - - 1 3 3 7

Biologicals 1 5 2 3 - 11

Complications, n (% of total operations)

None 65 (66.3) 183 (89.3) 48 (94.1) 88 (86.3) 21 (80.8) 406 (84.0)

Wound infection 2 (2.0) 4 (2.0) 1 (2.0) 1 (1.0) 1 (3.8) 9 (1.9)

Nervce irritation 4 (4.1) - - - 1 (3.8) 5 (1.0)

Bleeding 1 (1.0) 3 (1.5) 1 (2.0) 3 (2.9) 1 (3.8) 9 (1.9)

Stricture 3 (3.0) - - - - 3 (0.6)

Pain >4 weeks 1 (1.0) 1 (0.5) 1 (2.0) 2 (2.0) - 5 (1.0)

Other** 22 (22.4) 14 (6.8) - 6 (5.9) 2 (7.7) 44 (9.1)

Follow-up in months

Median 31.0 47.0 29.0 48.0 33.5 43.0

(IQR) (9-89) (14-93) (11-67) (17-91) (21-79) (14-87.5)

*Mammary region (n = 5), chest (n = 2), upper legs (n = 4), abdomen (n = 7), neck (n = 1), retroauricular area (n = 1), popliteal stump (n

= 1), sacrum (n = 3). **Hypergranulation (n = 35), hypertrophic scar (n = 4), hyperpigmentation (n = 2), delayed wound healing (i.e. >3

months; n = 3).

Table 3. Characteristics of surgery in each location

117

Figure 2. Outcomes of primary operations for each anatomical area.

118

DIScUSSIoN With a total of 482 operations performed in 113 patients and a median follow-up time

of 43 months this is one of the largest studies on surgical treatment for HS so far. The

percentage of men in our severely affected population was higher compared to the general

HS population.13,14 In agreement with other studies,14,15 men had significantly more often

involvement of the buttocks which is probably due to a higher density of terminal hair follicles.

The low percentage (10.6%) of Hurley stage III disease is probably an underestimation as

it was frequently impossible to discriminate between stage II and III from the description in

the medical charts. Although HS is regarded as a post-pubertal disease,16 20% of patients

were 16 years or younger at the onset of disease suggesting that a (pre-)pubertal onset is

not uncommon in severely affected patients. Similar to studies conducted in relatively milder

affected HS populations, 32% of our patients had a positive family history for HS.14,17 This

supports the finding that a positive family history is not associated with a more severe course

of the disease.14 The mean BMI of our patients was similar to another Dutch population,7 but

lower compared to studies from other countries.15,18 The difference could be explained by

demographic factors as well as by the selection bias in our study where patients with a BMI

≥35kg/m2 were excluded. Of our patients 80% were current/former smokers, underlining once

again the important role of tobacco in HS.13-15,18,19

Early diagnosis and proper treatment are crucial as HS tends to get more severe over time and

the risk of complications increases with longstanding disease.20 The median diagnostic delay in

our study was 6.5 years, others demonstrated delays of 3.3-12 years.15,21 In our study, surgery

under general anesthesia was performed after a median disease duration of respectively 12

years. Rompel et al.22 reported the results of surgery in patients with a mean disease duration

of 7 years, Kagan et al.23 in patients with a mean disease duration of 6.7 years (0.5-40 years)

and Mandal et al.24 in patients with a median disease duration of 6 years (range 1-30 years).

This illustrates that our population had substantial longstanding HS, making it difficult to

directly compare our results to others. The majority of our patients was previously operated

under local anesthesia by deroofing or wide excision (Table 1). Unfortunately we were not able

to determine the time between the first onset of symptoms and the first surgical intervention

in our study population, however, many patients report that it took several years. The mean

period between disease onset and the first surgical intervention in the patients described

by Bieniek et al.25 was 7.6 (±7.1) years. Therapeutic delays are thus substantial in HS. It is

therefore important that patients are referred to a dermatologist on a short notice for proper

diagnosis and treatment with systemic agents and surgery. Educating general physicians is thus

crucial.

119

Relapses due to irradical surgery occurred in 29% of the 363 primary operations. Studies on

radical excision with varying closing techniques showed relapse rates of 2.5-70%.10,22,25-29 None

of the 57 patients that were retrospectively studied by Kagan et al.23 had relapses after wide

excision, however, the mean follow-up time was relatively short (8.5 months). Van der Zee et

al.7 described a relapse rate of 17% after deroofing for Hurley stage I/II. The bottom line is that

studies on surgical treatments are very heterogeneous with respect to patient numbers, disease

severity, disease location, surgical techniques, definitions of surgical outcomes (e.g. relapses

and natural disease progression) and follow-up times, making direct comparisons impossible.

A new finding is that women had significantly higher relapse rates than men. It could be that

the pathogenesis of HS is more subjected to the influence of sex hormone levels (including

androgens and estrogens) in women, resulting in a more fluctuating and chronic course of

the disease. The female hormone estrogen has indeed an effect on the immune system:30

it attenuates amongst others neutrophilic inflammatory responses and the release of pro-

inflammatory cytokines such as TNF-α, IL-1β and IL-17 which are key players in HS.31,32

Clinically, this is reflected in the observation that exacerbations are frequently reported during

relatively hypo-estrogenic states (e.g. post-partum and during the premenstrual period) and

improvement during the use of estrogen containing contraceptive pills.33,34 Estrogens may thus

have a protective role during the course of HS. However, despite a fall in estrogen levels HS

usually improves after the fourth decade. This possibly results from a simultaneous decline in

androgen levels.35 To our surprise age, smoking, disease location and the use of co-medication

did not have a statistically significant effect on the risk of relapse. Natural disease progression

occurred frequently after surgery suggesting that the effectiveness of surgery stays limited to

the operated area. Obviously, the question then arises whether saving as much healthy tissue

as possible is actually a proper aim in HS. The main focus of future studies should therefore be

whether wide excision alone or the use of minimal invasive surgical techniques (e.g. the STEEP)

with perioperative immunosuppression should be preferred to prevent natural progression of

the disease. Similar to other studies, complications occurred in 16% of the operations.(10,22,25,29)

When operating the armpits, caution should be taken for the brachial plexus since this nerve

plexus is prone to iatrogenic injuries.36

Patients were satisfied regarding the medical effect of surgery under general anesthesia. Less

severely affected patients attributed the same median score to the deroofing technique under

local anesthesia.7 The cosmetic effect was rated lower than the medical outcomes in our study

which is understandable since the wounds always heal with scar tissue. Van Rappard et al.37

retrospectively studied the cosmetic results in a group of patients who were treated with

local excision and primary closure. In this study 83% of patients rated the cosmetic results

120

as reasonable or good, however, it is hard to directly compare these results to our study since

their patient population had less severe disease (Hurley stage I or II) and different outcome

measurements were used. A significant majority of our patients reported that surgery was the

best treatment they ever had for HS. This indicates that medical rather than cosmetic effects

are most important to patients, which was also pointed out by Van Rappard et al.37 Still, these

scores reflect that further improvement of surgical techniques is required in terms of both

medical and cosmetic outcomes.

Limitations

This study has a selection bias since patients with a BMI ≥35 kg/m2 are excluded for surgery.

Missing data due to the retrospective character of the study make some percentages less

reliable. Difficulties in distinguishing Hurley stage II from stage III made it impossible to

determine whether the relapse risk after surgery is affected by disease severity. The mean time

to wound healing could not be extracted from our data. A response rate to the questionnaires

of 63% indicates a risk of bias, even though there were no differences between responders and

non-responders in terms of gender and relapses.

conclusion

This study suggests that male gender and early onset of HS are risk factors for developing

severe HS. There are still long diagnostic and therapeutic delays for HS underlining the

importance of educating patients and primary health care physicians. Deroofing and STEEP

under general anesthesia lead to good medical and cosmetic results and should be performed

at an early stage of the disease. Deroofing should be reserved for Hurley stage I or limited

II disease whereas STEEP is indicated in extensive stage II and III disease. The risk of post-

operative relapses is significantly higher in women, possibly as a result of hormonal differences.

Prospective studies on surgical techniques with predetermined outcomes and validated patient

reported outcomes are required to develop guidelines for the appropriate choice of surgery.

121

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Blok JL, van Hattem S, Jonkman MF, Horvath B. Systemic therapy with immunosuppressive agents and

retinoids in hidradenitis suppurativa: a systematic review. Br J Dermatol 201; 2:243-52.

van der Zee HH, Prens EP, Boer J. Deroofing: a tissue-saving surgical technique for the treatment of mild to

moderate hidradenitis suppurativa lesions. J Am Acad Dermatol 2010; 63:475-480.

van Hattem S, Spoo JR, Horvath B, et al. Surgical treatment of sinuses by deroofing in hidradenitis


Lapins J, Sartorius K, Emtestam L. Scanner-assisted carbon dioxide laser surgery: a retrospective follow-up

study of patients with hidradenitis suppurativa. J Am Acad Dermatol 2002; 47:280-85.

Alharbi Z, Kauczok J, Pallua N. A review of wide surgical excision of hidradenitis suppurativa.

BMC Dermatol 2012; 12:9-5945-12-9.

Blok JL, Spoo JR, Leeman FW, et al. Skin-Tissue-sparing Excision with Electrosurgical Peeling (STEEP): a

surgical treatment option for severe hidradenitis suppurativa Hurley stage II/III.

J Eur Acad Dermatol Venereol 2014; 2: 379-82.

Ather S, Chan DS, Leaper DJ, Harding KG. Surgical treatment of hidradenitis suppurativa: case series and

review of the literature. Int Wound J 2006; 3:159-69.

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Revuz JE, Canoui-Poitrine F, Wolkenstein P, et al. Prevalence and factors associated with hidradenitis

suppurativa: results from two case-control studies. J Am Acad Dermatol 2008; 59:596-601.

Canoui-Poitrine F, Revuz JE, Wolkenstein P, et al. Clinical characteristics of a series of 302 French patients

with hidradenitis suppurativa, with an analysis of factors associated with disease severity.


Vazquez BG, Alikhan A, Weaver AL, et al. Incidence of Hidradenitis Suppurativa and Associated Factors:

A Population-Based Study of Olmsted County, Minnesota. J Invest Dermatol 2013; 133:97-103.

Alikhan A, Lynch PJ, Eisen DB. Hidradenitis suppurativa: a comprehensive review. J Am Acad Dermatol

2009; 60:539-61; quiz 562-3.

Canoui-Poitrine F, Le Thuaut A, Revuz JE, et al. Identification of Three Hidradenitis Suppurativa

Phenotypes: Latent Class Analysis of a Cross-Sectional Study. J Invest Dermatol 2013; 6:1506-11.

Sartorius K, Emtestam L, Jemec GB, Lapins J. Objective scoring of hidradenitis suppurativa reflecting the

role of tobacco smoking and obesity. Br J Dermatol 2009; 161:831-39.

Matusiak L, Bieniek A, Szepietowski JC. Hidradenitis suppurativa and associated factors: still unsolved

problems. J Am Acad Dermatol 2009; 61:362-65.

Lapins J, Ye W, Nyren O, Emtestam L. Incidence of cancer among patients with hidradenitis suppurativa.

Arch Dermatol 2001; 137:730-34.

Mebazaa A, Ben Hadid R, Cheikh Rouhou R, et al. Hidradenitis suppurativa: a disease with male


Rompel R, Petres J. Long-term results of wide surgical excision in 106 patients with hidradenitis


Kagan RJ, Yakuboff KP, Warner P, Warden GD. Surgical treatment of hidradenitis suppurativa: a 10-year

experience. Surgery 2005; 138:734-40; discussion 740-1.

Mandal A, Watson J. Experience with different treatment modules in hidradenitis suppuritiva: a study of

106 cases. Surgeon 2005; 3:23-26.

Bieniek A, Matusiak L, Okulewicz-Gojlik D, Szepietowski JC. Surgical treatment of hidradenitis suppurativa:

experiences and recommendations. Dermatol Surg 2010; 36:1998-2004.

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Ritz JP, Runkel N, Haier J, Buhr HJ. Extent of surgery and recurrence rate of hidradenitis suppurativa.

Int J Colorectal Dis 1998; 13:164-68.

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Ann Plast Surg 2001; 47:636-42.

Menderes A, Sunay O, Vayvada H, Yilmaz M. Surgical management of hidradenitis suppurativa.

Int J Med Sci 2010; 7:240-47.

Wollina U, Tilp M, Meseg A, et al. Management of severe anogenital acne inversa (hidradenitis

suppurativa). Dermatol Surg 2012; 38:110-17.

Nadkarni S, McArthur S. Oestrogen and immunomodulation: new mechanisms that impact on peripheral

and central immunity. Curr Opin Pharmacol 2013; 13:576-81.

Schlapbach C, Hanni T, Yawalkar N, Hunger RE. Expression of the IL-23/Th17 pathway in lesions of


van der Zee HH, de Ruiter L, van den Broecke DG, et al. Elevated levels of tumour necrosis factor (TNF)-

alpha, interleukin (IL)-1beta and IL-10 in hidradenitis suppurativa skin: a rationale for targeting TNF-alpha

and IL-1beta. Br J Dermatol 2011; 164:1292-98.

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Br Med J (Clin Res Ed) 1986; 292:245-48.

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Br J Surg 1988; 75:972-75.

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oophorectomy. J Clin Endocrinol Metab 2005; 90:3847-53.

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van Rappard DC, Mooij JE, Mekkes JR. Mild to moderate hidradenitis suppurativa treated with local

excision and primary closure. J Eur Acad Dermatol Venereol 2012; 26:898-902.

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9gENERAL DIScUSSIoN AND fUTURE PERSPEcTIVE

J.L. Dickinson-Blok

126

HS is evolving from a relative orphan disease towards being a renewed scientific topic.

Originally, HS was regarded as a disease of the apocrine sweat glands, hence the term

“hidradenitis suppurativa”. In 1952 it was dr. Brunsting who proposed, for the first time,

that the initial inflammation occurrs in the hair follicle with apocrine involvement occurring

only upon extension of the inflammatory process to deeper skin layers.1 Ever since, several

histological studies found that follicular hyperkeratization followed by occlusion are central

pathogenic events, rather than involvement of the sweat glands.2-5 Since no specific pathogenic

bacteria have been identified in HS, it has been suggested that aberrant immunity rather than

bacteria are responsible for the inflammatory reaction in HS6-8 The suspected association of HS

with other immune mediated diseases further supports a key role of aberrant immunity in its

pathogenesis.9

Many questions remain regarding the pathogenesis of HS and therefore the identification of

appropriate treatment targets is challenging. Although a wide arsenal of systemic agents and

surgical interventions have been described for HS, many patients are refractory to treatment.

Consequently, HS is a frustrating disease for both patients and clinicians. In this thesis we

aimed at gaining more insight in the pathogenesis of HS and explored both current and new

treatment options, including systemic and surgical therapies. The following chapter will discuss

the main findings of this thesis, combined with perspectives for future research.

To further investigate the histopathogenesis of HS we studied the morphology of the basement

membrane within the folliculopilosebaceous unit (FPSU), as shown in chapter 2. This was done

by performing periodic-acid Schiff (PAS) and immunofluorescence (IF) staining for the main

BMZ glycoproteins of perilesional HS skin and comparing this to skin of healthy volunteers.

We demonstrated relative upregulation of integrin α6β4 at the sebaceous glands of HS

patients. Integrin α6β4 is an important signaling molecule and its upregulation has also been

described in pulmonary tissue upon infection with pathogenic micro-organisms.10,11 It has

been hypothesized that integrins function as pattern recognition receptors (PRP’s) in lungs

that upon interaction with bacteria induce cellular responses that activate the innate immune

system and inflammation.10 This may also be true for upregulated integrins in HS. Although

bacterial cultures from HS lesions are often negative or only show commensal bacteria,

DNA-based analyses have revealed that the skin’s microbiome is much wider than previously

assumed.12 An aberrant composition of the skin’s microbiome has been linked to several other

inflammatory mediated skin diseases, including psoriasis and atopic dermatitis.13 Interestingly,

a relative deficiency of antimicrobial peptides (AMP’s) was demonstrated in HS lesions that

may promote bacterial propagation.14 Pathogenic changes in the skin’s microbiome may result

127

in chronic exposure of keratinocytes and Langerhans cells to pathogen-associated molecular

patterns (PAMPs), resulting in upregulation of PRPs and therefore also integrins.15 Several

clinical and histological findings further support a role for the microbiome in HS, namely: 1)

the microbiome composition in body folds differs from other areas, explaining the predilection

of HS lesions at these locations12 2) life style factors (smoking and diet) associated with HS as

well as hormonal factors influence the composition of the microbiome12 3) the composition of

the microbiome is largely determined by inherited factors,12 explaining the familial occurrence

of HS 4) sebaceous glands have shown to be diminished in volume and number in clinically

uninvolved skin of HS patients.16 The latter may promote increased infundibular friction due

to dimished sebum secretion but may also result in a diminished production of AMP’s by

sebocytes, further promoting bacterial colonization. Whether changes in the microbiome have

a causal effect in skin diseases or occur secondarily to an altered skin biology remains elusive.13

It would be interesting to investigate whether there are differences between sebocyte derived

AMP’s in HS patients and controls to determine the possible role of sebaceous glands in

bacterial colonization. Genome based techniques, like 16S RNA gene clone sequencing, may

be applied to study the microbiome in HS. In case an important role of the microbiome in HS is

identified, restoring its composition would be an interesting future therapeutic strategy.

An important finding was that we could not confirm the presence of the so called “PAS-gaps”

at the sebofollicular junction (SFJ) in HS skin as described by Danby et al.17 Neither did we find

diminished expression of specific glycoproteins (including type XVII collagen, type VII collagen,

laminin-332, and integrin α6β4) in the BMZ. Therefore we have strong doubts about the

primary importance of hair follicle fragility in the HS pathogenesis.

There is increasing evidence that HS is an immune mediated disease as the dysregulated

immune system plays a critical role in both the development and progression of HS. Therefore,

immunosuppressive agents have been recognized as a cornerstone treatment. In HS

overproduction of cytokines from both the innate (including IL-1β and TNF-α) and adaptive

immune system (including IL-10, IL-12, IL-17 and IL-23) has been observed in skin tissue.14,18-20

Additionally, diminished expression of IL-22 has been demonstrated, probably resulting from

increased IL-10 production. This may contribute to the relative deficiency of AMP’s in HS

skin.14 As the predominant cytokines driving the inflammatory reaction in HS have yet to be

determined and consensus is lacking, the choice for a specific immunosuppresive agent is

mainly based on the clinicians’ experience.

HS is associated with genetic predisposition. Heterozygote mutations in the g-secretase genes

have been identified in familial HS with an autosomal dominant inheritance pattern.21,22 In

128

our clinic we encountered five HS patients who were also diagnosed with Down syndrome

(DS), suggesting that an association between these two conditions is possible. In chapter 3 we

formulated a hypothesis that may link Down syndrome (DS) to HS via functional deficiency

of g-secretase. Dysfunctional or deficient g-secretase may induce HS by impairing Notch

signaling pathways. Notch signaling controls epidermal cell proliferation and differentiation

and is therefore involved in hair follicle and sebaceous gland maintenance.21 Furthermore, it

may promote epidermal cyst formation and impaired production of sebaceous glands, both

important characteristics of HS. Whether DS and HS are truly associated requires investigation

in a larger group of DS patients. Further work should focus on the role of g-secretase in the

skin and the hair follicle specifically. Furthermore, gene mapping techniques, including next-

generation sequencing, may be applied to identify relevant mutations in genes encoding for

other proteins in the g-secretase complex or proteins involved in the Notch signaling pathway.

Chapter 4 describes the gene expression profile of HS affected tissue. Here we show significant

upregulation of genes involved in pathways comprising amongst others leucocyte migration,

inflammatory and immune responses as well as atherosclerosis signaling in lesional HS skin

compared to clinically uninvolved skin. These results have yet to be confirmed with for

instance quantitative real-time polymerase chain reaction (PCR) analyses and on protein level.

No differences were observed in whole blood mRNA expression between HS patients and

healthy subjects. This implicates that activated cells in HS reside in affected tissue, probably

because leucocytes migrate from the circulation into skin tissue by an as yet unknown trigger.

Inflammation in HS is thus restricted to the skin of specific anatomical areas and therefore it

may be considered as a localized rather than a generalized skin disease. However, an increased

frequency of metabolic syndrome has been shown in HS, implicating that it actually may be

a systemic disease.23 It remains unclear whether these metabolic changes occur secondary

to the chronic inflammation and adverse lifestyle habits associated with HS or whether

primary metabolic alterations trigger HS. Either way, systemic immunosuppressive and anti-

inflammatory agents are important for preventing progression of HS to other skin regions.

Future studies should also establish the role of topically applied agents like topical resorcine

15% cream,24 topical antibiotics and zinc glucoanate,25,26 especially in disease phenotypes

where only one or two anatomical areas are involved.

Chapter 5 describes a systematic review on the effectiveness of systemic immunosuppressive

agents and retinoids in HS. Here we show that the quality of performed studies, to date,

129

is generally poor, making it difficult to make any therapeutic recommendations. The best

clinical results were found for the TNF-α-inhibitors adalimumab and infliximab, confirming

the importance of TNF-α in HS. Additionally, promising results were identified for the retinoid

acitretin as it was effective in 95% of the 22 described patients. Isotretinoin showed a poor

response. This may be explained by the reduction in sebaceous glands in HS, as sebaceous

glands are important targets of isotretinoin.27 Although colchicine is a potent IL-1β inhibitor

and suppressor of neutrophils,28 it was not effective in HS. In conclusion, better studies are

needed to determine the effect of other immunosuppressive agents showing promising results

in small studies, like dapsone and cyclosporine.

As mentioned above, IL-12 and IL-23 have been found to be abundantly expressed by

macrophages in lesional HS skin.19 Additionally, Th-17 cell upregulation has been observed

in HS tissue.19 Similar to psoriasis, Th-17 cells are known to produce IL-17 and IL-21 which

can lead to proinflammatory cytokine (IL-1β, IL-6 and TNF-α) production by keratinocytes,

resulting in neutrophil, macrophage and lymphocyte attraction.29 Targeting the IL-23/Th17 axis

with the biologic agent ustekinumab could therefore be effective in treating HS.

In chapter 6 we show in an open label study, for the first time, that ustekinumab can be

applied in HS, as the majority of patients showed improvement. The results were not inferior to

the results found for adalimumab in a large randomized controlled trial,30 nor compared to the

IL-1 receptor antagonist anakinra in a small open label study.31 As inflammatory marker levels

are higher in HS compared to psoriasis (where ustekinimab is an approved treatment option18)

we would recommend to adjust the standard psoriasis schedule by increasing administration

frequency and dosage. Eventually, clinical trials are warranted to compare IL-12/IL-23

inhibition to the current gold standard of TNF-α-inhibition in HS. Furthermore, it is important

to investigate in larger studies whether certain clinical characteristics are predictive for a

response to ustekinumab, including HS phenotype (for instance wide spread Hurley II disease

versus localized Hurley III disease), life style factors (smoking and obesity) and co-morbidities.

Besides treatment effect, chapter 6 also describes protein expression in serum of patients at

baseline and during the study. At baseline, a significant difference was detected between

healthy controls and HS patients in the expression of 54 serum proteins. These proteins are

probably produced by activated cells present in skin tissue. Further investigation of these

protein levels could possibly lead to putative biomarkers for diagnostic purposes or monitoring

disease progression. Although we did not discover a specific biomarker reflecting the

therapeutic effect of ustekinumab, low levels of enzyme leukotriene A4-hydrolase (LTA4H) in

patients combined with relatively mild clinical disease severity may be prognostic for a good

effect of ustekinumab.

130

Surgery is an important part of HS Hurley stage II/III treatment as systemic therapy alone is

never sufficient for heal previously formed sinus tracts and scarring. These sinus tracts provide

access for bacteria to invade the dermis, leading to repetitive inflammation and further

extension of the disease. Several surgical - as well as closure techniques have been previously

proposed for HS.9 General anesthesia is preferred when large areas require surgical intervention

or in cases where patients refuse local anesthetics.

In chapter 7 we describe a new surgical technique to approach moderate to severe HS Hurley

stage II/III: the skin tissue-sparing excision with electrosurgical peeling (STEEP) procedure.

By performing tangential excisions and exploring the wound beds with a probe, all lesional

tissue can be removed with minimal excision of healthy skin. This can lead to a shorter healing

time and less post-surgical complications, (e.g contractures), compared to the traditional wide

excision. The wounds are healed by secondary intention allowing continuous wound drainage

and therefore the risk of post-operative inflammation is diminished. In chapter 8 long term

results (median follow-up time of 43 months) of the STEEP procedure and deroofing under

general anesthesia were retrospectively studied. Here we show that natural progression of the

disease outside the surgical scar but within the operated anatomical region occurred in 34%

of patients. True relapses due to irradical surgery were seen in 29% of patients. However, in a

subsequent prospective case series of 27 patients with a follow up time of 12 months by our

group, relapses were observed in only one patient (Janse et al.; unpublished data). Due to the

relatively high percentage with natural progression of the disease, future studies should focus

on proper planning of surgery, whether the use of perioperative immunosupressiva improves

surgical outcomes (time to wond closure, relapse rate, natural progression of the disease)

and whether tissue saving procedures are superior to wide excision regarding these surgical

outcomes. Also, ultrasound imaging prior to the operation may help the surgeon in estimating

the extensiveness of fistulas and therefore assist in the choice for a specific technique.32

Finally, as many closure techniques have been proposed in HS, studies should be performed to

investigate the type of indications where wound closure with grafts or flaps should be preferred

over secondary intention healing. The choice will mainly depend on experience of the surgeon,

the location of the disease, the size of the wound and patient’s ability to take care of an open

wound.

131

coNcLUSIoNS AND fINAL coNSIDERATIoNSThe multifactorial pathogenesis of HS remains elusive, complicating the development of new

treatment strategies. Follicular occlusion may be caused by a primary keratinization disorder or

may result from an overactive innate immune system, with a possible causative or secondary

role of the skin’s microbiome. The contribution of hormones, genetics and environmental

factors requires further investigation. Consensus should be reached on what the treatment

goal should be in HS and on what outcome measures must be applied in future clinical trials

focusing on topical, systemic and surgical treatments. The ultimate goal would be to develop

individualized treatment strategies for HS.

132

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Attanoos RL, Appleton MA, Douglas-Jones AG. The pathogenesis of hidradenitis suppurativa: a closer 3.

look at apocrine and apoeccrine glands. Br J Dermatol 1995; 133:254-58.

Sellheyer K, Krahl D. “Hidradenitis suppurativa” is acne inversa! An appeal to (finally) abandon a 4.

misnomer. Int J Dermatol 2005; 44:535-40.






Sartorius K, Killasli H, Oprica C, et al. Bacteriology of hidradenitis suppurativa exacerbations and deep 7.

tissue cultures obtained during carbon dioxide laser treatment. Br J Dermatol 2012; 166:879-83.


are the Treatment of Choice? Acta Derm Venereol 2014; 6:699-702 .

Zouboulis CC, Desai N, Emtestam L, et al. European S1 guideline for the treatment of hidradenitis 9.

suppurativa/acne inversa. J Eur Acad Dermatol Venereol 2015; 4:619-44.

10. Ulanova M, Gravelle S, Barnes R. The role of epithelial integrin receptors in recognition of 10.

pulmonary pathogens. J Innate Immun 2009; 1:4-17.

Gravelle S, Barnes R, Hawdon N, et al. Up-regulation of integrin expression in lung adenocarcinoma 11.

cells caused by bacterial infection: in vitro study. Innate Immun 2010; 16:14-26.

Grice EA, Segre JA. The skin microbiome. 12. Nat Rev Microbiol 2011; 9:244-53.

Cho I, Blaser MJ. The human microbiome: at the interface of health and disease. 13. Nat Rev Genet

2012; 13:260-70.

Wolk K, Warszawska K, Hoeflich C, et al. Deficiency of IL-22 contributes to a chronic inflammatory 14.

disease: pathogenetic mechanisms in acne inversa. J Immunol 2011; 186:1228-39.

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Zeeuwen PL, Boekhorst J, van den Bogaard EH, et al. Microbiome dynamics of human epidermis 15.

following skin barrier disruption. Genome Biol 2012; 13:R101-2012-13-11-r101.

Kamp S, Fiehn AM, Stenderup K, et al. Hidradenitis suppurativa: a disease of the absent sebaceous 16.

gland? Sebaceous gland number and volume are significantly reduced in uninvolved hair follicles from

patients with hidradenitis suppurativa. Br J Dermatol 2011; 164:1017-22.








van der Zee HH, Laman JD, de Ruiter L, et al. Adalimumab (antitumour necrosis factor-alpha) 20.

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Pink AE, Simpson MA, Desai N, et al. gamma-Secretase mutations in hidradenitis suppurativa: new 21.

insights into disease pathogenesis. J Invest Dermatol 2013; 133:601-07.

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Hidradenitis Suppurativa. JAMA Dermatol 2015; 151:688-70.

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patients with acne inversa. PLoS One 2012; 7:e31810.

Boer J, Jemec GB. Resorcinol peels as a possible self-treatment of painful nodules in hidradenitis 24.

suppurativa. Clin Exp Dermatol 2010; 35:36-40.

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dermatosis. J Eur Acad Dermatol Venereol 2011; 25:1146-52.

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approach. A pilot study. Dermatology 2007; 214:325-27.

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inflammasome. Nature 2006; 440:237-41.

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135

137

10NEDERLANDSE SAMENVATTINg

J.L. Dickinson-Blok

138

Hidradenitis suppurativa (HS) is een chronische huidziekte die gekenmerkt wordt door

inflammatoire noduli, nodi en abcessen. Deze ontstekingen zijn met name gelokaliseerd in de

plooien van het lichaam, zoals de liezen, oksels en de billen en genezen vaak met littekens.

De ziekte komt bij ongeveer 1-4% van de bevolking voor en treft relatief meer vrouwen dan

mannen.

De primaire afwijking bij patiënten met HS is dat de haarfollikels/haarzakjes verstopt

raken (folliculaire plugging) waardoor deze zich geleidelijk gaan vullen met talg en pus.

Uiteindelijk barsten de haarfollikels open waardoor de inhoud zich naar het huidoppervlak

beweegt, alsmede zich horizontaal verspreidt naar het omliggende weefsel (de dermis

ofwel de lederhuid). Als reactie op dit lichaamsvreemde materiaal in de dermis komt een

ontstekingsproces op gang die vervolgens verstopping van omliggende haarzakjes en de

vorming van zogenaamde fistelgangen stimuleert. Deze fistelgangen vormen onderhuidse

verbindingen tussen de ontstekingen en bestaan uit cellen die de oorspronkelijke haarzakjes

bekleedden. Dit onderhuidse gangenstelsel staat in open verbinding met de oppervlakte van de

huid waardoor ze een relatief eenvoudige toegangsweg voor bacteriën naar het onderhuidse

weefsel vormen, wat weer leidt tot verdere ontstekingen. De fistelgangen leveren daardoor een

belangrijke bijdrage aan de chroniciteit van de ziekte.

De oorzaak van HS is grotendeels onbekend. Genetische aanleg lijkt een rol te spelen

aangezien het vaak meerdere mensen binnen een familie treft. Daarnaast blijkt uit onderzoek

dat roken en overgewicht belangrijke risicofactoren zijn voor zowel het krijgen van HS als

voor een ernstiger verloop van de ziekte. De hormoonhuishouding lijkt ook een rol te spelen

aangezien HS meestal na de puberteit ontstaat, bij sommige vrouwen voor de menstruatie

opvlamt en de ontstekingsactiviteit af kan nemen door het gebruik van orale anticonceptiva

(‘de pil’).

Acute ontstekingen kunnen zeer pijnlijk zijn waardoor patiënten gehinderd worden in

hun dagelijks leven en soms zelfs arbeidsongeschikt raken. De pus die vrijkomt kan een

onaangename geur afscheiden wat leidt tot veel schaamte bij patiënten. Daarnaast zijn de

littekens cosmetisch storend en kunnen zelfs leiden tot bewegingsbeperkingen. Het is daarom

niet verwonderlijk dat HS de kwaliteit van leven vaak ernstig beïnvloedt.

HS is momenteel niet te genezen en daarom is de behandeling gericht op bestrijding van acute

ontstekingen, het opheffen van chronische ontstekingen en het zoveel mogelijk voorkomen

van nieuwe ontstekingen. Deze doelen kunnen bereikt worden met lokale therapie (o.a.

antibiotische crème/zalf/lotion, retinoïden of lokale corticosteroiden), systemische therapie

(antibiotica of middelen die het immuunsysteem remmen) of chirurgische ingrepen. Vaak

worden deze behandelingen gecombineerd om een optimaal resultaat te bereiken.

139

Om tot betere behandelingen te komen is het noodzakelijk dat er meer kennis komt over de

ontstaanswijze (pathogenese) van HS en zijn er studies nodig om nieuwe behandelingen te

onderzoeken. In dit proefschrift hebben we ons daarom gericht op zowel de pathogenese als

op de effectiviteit van bestaande en nieuwe behandelingen voor HS.

In hoofdstuk 2 hebben we haarfollikels van patiënten met HS vergeleken met de haarfollikels

van gezonde mensen. In deze studie konden wij met periodic acid-Schiff (PAS) en

immunofluorescentie (IF) kleuringen niet bevestigen dat de basaalmembraan ter hoogte van

de overgang van de talgklier naar de haarfollikel bij HS patiënten fragieler is dan bij gezonde

mensen. We toonden wel met IF-kleuringen aan dat patiënten met HS een hogere expressie

van het eiwit integrine α6β4 langs de basaalmembraan van de talgklieren hebben dan

gezonde mensen. Hypothetisch zou deze verhoogde expressie veroorzaakt kunnen worden

door veranderingen in de bacteriële samenstelling van de huid bij patiënten, het zogenaamde

microbioom. Deze integrines zouden een bijdrage kunnen leveren aan activatie van het

immuunsysteem en een rol kunnen spelen bij het vaker voorkomen van plaveiselcelcarcinomen

bij patiënten met HS.

In hoofdstuk 3 hebben we een hypothese geformuleerd die verklaart waarom HS mogelijk

vaker voorkomt bij patiënten met het syndroom van Down. Hierbij staat het enzym g-secretase

centraal. Mutaties in dit enzymcomplex zijn beschreven bij familiare HS en kunnen via

verstoring van de zogenaamde ‘Notch signaling pathway’ leiden tot de vorming van de

karakteristieke huidafwijkingen bij HS. Bij patiënten met het syndroom van Down is het

mogelijk dat deze ‘Notch signaling pathway’ verstoord is door een tekort aan g-secretase.

Dit tekort zou bij patiënten met het syndroom van Down kunnen ontstaan doordat het

beschikbare g-secretase verbruikt wordt om de vehoogde hoeveelheid amyloid precursor

protein (APP) die bij dit syndroom tot expressie komt te verwerken. Daarnaast kunnen

verhoogde concentraties APP folliculaire plugging bevorderen. Tot slot hebben patiënten met

het syndroom van Down vaker overgewicht en zijn immunologische stoornissen een bekend

verschijnsel bij dit syndroom. Al deze factoren vergroten het risico op de ontwikkeling van HS

bij het syndroom van Down.

140

Hoofdstuk 4 beschrijft het genetische expressie profiel van HS in zowel de huid als het bloed

van patiënten. Met behulp van ‘mRNA microarray analyses’ laten we zien dat in klinisch

gezonde HS huid andere genen tot expressie komen dan in de ontstoken HS huid. Zoals

verwacht betreft dit met name genen die betrokken zijn bij ontstekingsprocessen. Tevens werd

betrokkendheid van atherosclerotische processen aangetoond in de aangedane huid, een

bevinding die de associatie tussen HS en het metabool syndroom ondersteunt. Er was geen

verschil aantoonbaar tussen genexpressie van HS patiënten en gezonde mensen in het bloed.

De resultaten van deze studie suggereren daarom dat de ontstekingscellen die betrokken zijn

bij HS zich beperken tot de aangedane huid en niet door het bloed circuleren. Ondanks dat de

inflammatie zich lokaal manifesteert zijn systemische middelen belangrijk om te voorkomen

dat de ontstekingsactiviteit van HS zich uitbreidt naar andere regio’s van het lichaam. Het blijft

onduidelijk of de met HS geassocieerde metabole veranderingen secundair aan de chronische

inflammatie en ongezonde levensstijl van veel HS patiënten ontstaan, of dat metabole

veranderingen primair aanwezig zijn en het risico op het ontwikkelen van HS verhogen.

In hoofdstuk 5 wordt in een systematisch review de effectiviteit van alle beschikbare

immuunsuppressieve therapieën en retinoïden voor HS onderzocht. We laten zien dat de

studies die verricht zijn naar deze behandelingsmogelijkheden vaak van lage kwaliteit zijn. De

beste resultaten werden geboekt met de tumor necrosis alpha (TNF-α) remmers adalimumab

en inflximab. TNF-α remmers behoren tot de zogeheten biologicals. Biologicals zijn

medicijnen die specifieke signaaleiwitten, zoals cytokines of receptoren, die betrokken zijn bij

ontstekingsprocessen uitschakelen en zo een ziekteproces gericht kunnen beïnvloeden. Naast

de TNF-α remmers werden ook goede resultaten behaald met het orale retinoïd acitretine.

De effectiviteit van isotretinoine, een ander soort retinoïd, was echter teleurstellend. Dit kan

worden verklaard uit het feit dat het belangrijkste werkingsmechanisme van isotretinoine

gericht is op reductie van de acitviteit van talgklieren, terwijl uit eerdere studies en uit onze

bevindingen in hoofdstuk 2 blijkt dat de talgklieren bij HS patiënten juist vaak afwezig of

verkleind zijn. Ook colchicine, een potente IL-1β en neutrofiele granulocyten remmer, blijkt

weinig effectief te zijn. Klinische studies van goede kwaliteit zijn nodig om de effectiviteit van

andere immuunsuppressieve middelen, zoals ciclosporine en dapson, alsmede van nieuwe

middelen verder te onderzoeken.

In eerdere studies werden aanwijzingen gevonden dat betrokkenheid van de IL-23/Th-17 as

een belangrijke rol zou kunnen spelen in de ontstekingscascade van HS. In hoofdstuk 6

141

onderzoeken wij in een open label studie of remming van deze IL-23/Th-17 as met de

biological ustekinumab leidt tot klinische verbetering van HS in 17 patiënten. Bij 83% van

de patiënten verbeterde de belangrijkste klinische score, de zogenaamde modified Sartorius

score (mSS), met 25-50%. Het primaire eindpunt van 50% afname van de score werd gehaald

in 35% van de patiënten. Ustekinumab zou dus een potentiële behandelingsoptie voor HS

kunnen zijn. De effectiviteit zou vergroot kunnen worden door intensievere doseringsschema’s

toe te passen bij HS. Uiteraard zijn gerandomniseerde dubbelblinde studies nodig om de

effectiviteit van ustekinumab te bevestigen.

In dezelfde studie werd middels microarray analyses op serum geen diagnostische biomarker

voor HS geïdentificeerd, noch werd er een biomarker gevonden die de activiteit van de

ziekte reflecteert. Een trend werd echter waargenomen dat patiënten met een goede respons

op ustekinumab relatief lagere concentraties van leukotriene A4-hydrolase, een enzym dat

betrokken is bij ontstekingsprocessen, in het serum tot expressie brachten en dat ze klinisch

minder ernstige HS hadden dan patiënten met een slechte respons op ustekinumab. Derhalve

zouden lage concentraties van leukotriene A4-hydrolase in combinatie met een relatief milde

klinische ziekteactiviteit voorspellend kunnen zijn voor een goede respons op ustekinumab.

Chirurgie is een belangrijk onderdeel bij de behandeling van HS, met name bij de ernstige

gevallen waar zich reeds fistelgangen hebben gevormd. Het doel van chirurgie is om al het

aangedane weefsel te verwijderen aangezien dit een bron van terugkerende ontstekingen

is. Verschillende chirurgische technieken zijn beschreven bij HS, waarvan ruime excisie de

meest bekende techniek is. Een nadeel is dat hierbij ook relatief veel gezond weefsel wordt

weggehaald. Chirurgische behandelingen kunnen, afhankelijk van de uitgebreidheid van het

ziektebeeld, zowel onder lokale als algehele anesthesie worden uitgevoerd.

In hoofdstuk 7 wordt een nieuwe chirurgische techniek beschreven voor matige tot

ernstige HS, de zogenaamde ‘Skin Tissue-sparing Excision with Electrosurgical Peeling’

(STEEP) procedure. Deze chirurgische techniek heeft als doel al het aangedane weefsel te

verwijderen, waarbij tegelijkertijd zoveel mogelijk gezond weefsel wordt gespaard. Er worden

opeenvolgende horizontale excisies verricht die steeds dieper het weefsel ingaan totdat gezond

weefsel te voorschijn komt. Door met een sonde de wondranden nauwkeurig te checken op

resterende ontstekingen en fistelgangen, wordt het risico op resterend ‘ziek’ weefsel beperkt

tot een minimum. Doordat de wondoppervlaktes zo klein mogelijk worden gehouden is het

risico op complicaties minder groot dan bij ruime excisies. De wonden worden na de operatie

open gelaten zodat er mogelijkheid is tot continue drainage van het wondbed.

142

De langetermijn resultaten van de STEEP procedure worden in hoofdstuk 8 beschreven.

Tussen 1999 en 2013 werden er op de afdeling Dermatologie in het UMCG 113 mensen een

of meerdere keren behandeld middels deze techniek, waarbij in totaal 482 operaties werden

uitgevoerd. Na een mediane follow-up van 43 maanden werd natuurlijke progressie van

de ziekte buiten het geopereerde gebied in 34% van de patiënten gezien. Daadwerkelijke

recidieven na een operatie traden uiteindelijk op in 29% van de patiënten. Toekomstige

studies zijn nodig om te bepalen of gelijktijdig gebruik van ontstekingsremmende of

immuunsuppressieve middelen de kans op het terugkeren van de ziekte na een operatie

verlagen. Daarnaast moet er meer duidelijkheid komen of de effectiviteit van weefselsparende

operaties gelijk is aan die van ruime excisies.

143

coNcLUSIES De oorzaak van HS blijft grotendeels onduidelijk, wat de ontwikkeling van nieuwe

behandelingsstrategieën bemoeilijkt. De rol van hormonen, genetische aanleg en

omgevingsfactoren dient nader onderzocht te worden. Het is belangrijk om consensus te

bereiken over de te gebruiken uitkomstmaten in toekomstige studies zodat verschillende

behandelingen beter met elkaar vergeleken kunnen worden. Het ultieme doel is om

geïndividualiseerde behandelingsstrategieën voor HS te ontwikkelen.

145

APPENDIcES

J.L. Dickinson-Blok

146

DANKwooRDEen promotietraject is een persoonlijke reis vol uitdagingen. De mensen om me heen, die me

op welke manier dan ook stimuleerden en/of ondersteunden, waren goud waard en daar wil ik

graag nog even bij stilstaan.

Mijn promotor Prof. Dr. M.F. Jonkman. Beste Marcel, tijdens mijn eerste jaar bood je me dit

promotietraject aan. Je gaf me je vertrouwen en de vrijheid om zelfstandig te werken maar

stond daarnaast altijd laagdrempelig klaar om me verder te helpen met ideeën voor projecten.

Je snelle en creatieve denkwijze werkt ontzettend stimulerend en heeft me laten inzien hoe

leuk wetenschap is. Bedankt voor alles!

Mijn co-promotor dr. Horváth. Beste Barbara, jouw bevlogenheid, intelligentie en enthousiasme

maken dat je altijd weer met fantastische ideeën voor nieuwe projecten komt en hebben ons

gebracht waar we vandaag staan. Ondanks alle taken die er op je schouders rusten ben je er

altijd als het nodig is. Jouw steun, warmte en vertrouwen zijn van onschatbare waarde voor me

geweest.

Dear members of the reading committee, Prof. dr. B. van der Lei, Prof. dr. E.P. Prens and Prof.

G.B.E. Jemec. Thank you for reading and reviewing my thesis.

Mijn paranimfen Kasia en Ineke. Dat jullie me bijstaan op deze belangrijke dag betekent veel

voor me. Lieve Kasia, de laatste jaren hebben we alle highs and lows gedeeld. We hoeven

elkaar maar aan te kijken om te weten wat de ander denkt. Je hebt een groot hart en onze

vriendschap is een van de mooiste dingen die ik heb gekregen tijdens dit promotietraject.

Lieve Ineke, illustrator heldin. Jouw warme persoonlijkheid gecombineerd met je aanstekelijke

gedrevenheid maakt werken met jou ontzettend leuk. Bedankt voor je onmisbare bijdrage

aan de BMZ en je input tijdens de voorbereiding op de verdediging. Ik hoop dat we nog

veel onderzoeken gaan uitvoeren om HS beter te begrijpen en vooral ook gezellige dingen

daarbuiten blijven ondernemen!

147

Katherine Li and Carrie Brodmerkel. It was a pleasure working with you. Thank you for your

important contribution to chapters 4 and 6. Peter Horvátovich, thank you for sharing your

knowledge with us and your contribution to chapter 6.

Dr. J.R. Spoo. Beste Julia, we delen onze interesse voor hidradenitis suppurativa en je bent een

expert op het gebied van de STEEP. Bedankt voor jouw belangrijke bijdrage aan en de prettige

samenwerking tijdens de totstandkoming van hoofdstuk 7 en 8. De STEEP staat nu definitief

op de kaart!

Dr. J.B. Terra. Beste Jorrit, jij was degene die me liet inzien dat de wetenschap de juiste weg

was voor mij. Ik kan je daarvoor niet genoeg bedanken. Jouw wetenschappelijke en klinische

ervaring waren onmisbaar voor hoofdstuk 8. Daarnaast heeft jouw voortreffelijke PR ervoor

gezorgd dat de term STEEP helemaal ingeburgerd is op onze afdeling!

Janneke Huizinga, bedankt voor je enthousiasme en de fijne samenwerking. Je bent onmisbaar

voor onze patienten en in ons HS team!

Drs. S. van Hattem. Lieve Simone, ook jouw bijdrage was zeer belangrijk. Bedankt voor de fijne

samenwerking en je oprechte interesse. Ik mis je in Groningen.

Marieke Boersma, je hebt heel wat uren gespendeerd in ons retrospectieve onderzoek. Bedankt

voor je bijdrage en veel succes met je carrière!

Prof. Dr. P.J. Coenraads. Beste Pieter-Jan, mijn eerste stappen op wetenschappelijk en

dermatologisch gebied zette ik onder jouw begeleiding en mede door jouw steun en

vertrouwen werd ik aangenomen voor de opleiding. Ik ben je hier ontzettend dankbaar voor.

De overige stafleden: Sylvia Kardaun, Marie-Louise Schuttelaar, Marja Oldhoff en Emöke

Rácz. Bedankt voor de fijne samenwerking. Marie-Louise en de dames van het roosterbureau,

dank voor het realiseren van een aantal onderzoeksdagen in de afrondende fase van mijn

proefschrift.

148

De steun vanuit de gehele AIOS groep tijdens de laatste maanden van de afronding van mijn

proefschrift was geweldig. Jullie collegialiteit gaf me het laatste beetje lucht dat ik nodig had.

Hierbij wil ik Susanne, Marjolein, Ruud en Christiaan, partners in crime vanaf het begin van

de opleiding, nog speciaal noemen. Lieve Suus en Marjo, we are so good together! Met zijn

drieën vormen we een perfect team en ik ben ontzettend blij met onze vriendschap. Jullie zijn

geweldige dermatologen en ik ben heel trots op jullie! Ruud en Chris, de perfecte ingrediënten

voor humor of juist een goed gesprek . “Liefde is alles wat er is”, een beter cadeau hadden

jullie op dat moment niet kunnen geven, heel veel dank.

Daarnaast wil ik Piet Toonder bedanken voor de vele foto’s die hij heeft gemaakt en zijn ICT

ondersteuning. En alles altijd met een lach!

De mensen van het laboratorium. Hendri Pas, voor vragen over IF kon ik altijd bij je terecht.

Bedankt dat ik al mijn serum en biopten kon opslaan in het lab. Janny en Gonnie, hartelijk

bedankt voor het snijden en kleuren van de biopten!

Dr. A.M.G. Pasmooij. Beste Marjon, bedankt voor de discussies en je hulp in genetica land!

“Echte vrienden zie je niet omdat ze achter je staan”

Lieve Maike, dank voor het vertalen van de Spaanse artikelen in hoofdstuk 5 en voor alles

daarbuiten! Marije, Monique, Saskia en Iris, jullie maken Groningen nog steeds een “feestje”!

Ellen, je bent er altijd in elk opzicht, dank je wel! Maeyke en Sebastiaan, jullie gezeligheid en

culinaire kunsten geven me altijd weer energie. Ewout en Maria, onze vakanties en weekendjes

zijn de beste manier om op te laden. Maria, bedankt voor het lezen van de Nederlandse

samenvatting in je verlof! Ijsbrand, Martzen, Warner, Sophie, Thomas, Ianthe, Edwin D, Helma,

Dionne en Edwin S. bedankt voor alle gezelligheid! Linda, Marike, Henrike, Jan Wendel,

Willem, Imre, Lieke en Maike: het is altijd weer thuiskomen bij jullie, bedankt voor jullie

interesse en betrokkenheid.

Lieve Annemarie, wat heb ik het met jou getroffen. Bedankt voor de fijne gesprekken, je

humor en je adviezen.

149

Dear Bill, despite the long distance between us you have always managed to stay actively

involved in our lives. Thank you so much for your emotional support and thoughtfulness.

Lieve Thomas, broederliefde kent geen grenzen. Je bent altijd actief betrokken geweest bij alles

wat ik doe en bereid je steentje bij te dragen. Ik bewonder de manier waarop jij in het leven

staat waarbij je je dromen volgt en je talent gebruikt. Mensen voelen zich thuis bij jou en dat is

niet voor niets. Je hebt een groot hart en ik ben ontzettend trots op je.

Lieve zus, Suzanne. Onze telefoons zijn van onschatbare waarde, dat zal de hele familie

beamen. Ondanks de fysieke afstand ben je namelijk altijd dichtbij en heel belangrijk voor

me. Als ik het even niet zag zitten bood je altijd een luisterend oor en dat heeft veel voor

me betekend. Michiel, ik ben zo blij dat mijn zus zo’n leuke man heeft als jij! Mijn geweldige

neefjes Jules, Jesse en Joël, wat ben ik trots op jullie!! Als ik bij jullie ben kan ik alleen maar

genieten en vooral heel veel lachen.

Lieve papa en mama, zonder jullie was ik nooit zo ver gekomen. Jullie liefde, steun en

vertrouwen in mij lijken geen grenzen te kennen. Ik vind het fantastisch hoe jullie ons alle drie

de ruimte en vrijheid hebben gegeven om ons leven in te richten zoals we wilden en ons te

ontwikkelen tot de personen die we zijn. Een betere basis had ik mij niet kunnen wensen en

daar ben ik jullie oneindig dankbaar voor.

En tot slot mijn fantastische man. Lieve Michael, dat ik mijn leven met jou mag delen is mijn

grootste geluk. Je hebt me altijd gestimuleerd het beste uit mezelf te halen en niet aan mezelf

te twijfelen. Jouw aandeel in dit proefschrift is dan ook niet in woorden uit te drukken. Je bent

een prachtig persoon en samen met jou ga ik alle uitdagingen in het leven vol vertrouwen

tegemoet!

150

LIST of PUBLIcATIoNS J.L.Blok, K.Li, C. Brodmerkel, P. Horvátovich, M.F. Jonkman, B. Horváth. Ustekinumab in

hidradenitis suppurativa: a clinical open label study with analyses of the protein expression

profile in serum. Submitted.

J.L. Blok, K. Li, C. Brodmerkel, B. Horváth, M.F. Jonkman. Gene expression profiling of skin and

blood in hidradenitis suppurativa. Submitted.

J.L. Blok, I.C. Janse, B. Horváth, M.F. Jonkman. Increased expression of integrin α6β4 at the

basement membrane zone lining the sebaceous glands in hidradenitis suppurativa. Acta Derm

Venerol. 2015. doi: 10.2340/00015555-2186. [Epub ahead of print]

J.L. Blok, M. Boersma; J.B. Terra, J.R. Spoo, F.W.J. Leeman, E.R. van den Heuvel, J. Huizinga,

M.F. Jonkman, B. Horváth, MD PhD. Surgery under general anesthesia in severe hidradenitis

suppurativa: a study of 363 primary operations in 113 patients. J Eur Acad Dermatol Venereol

2015 doi: 10.1111/jdv. 12952

Blok JL, Jonkman MF, Horvath B. The possible association between hidradenitis suppurativa

and Down syndrome: is increased APP expression resulting in impaired Notch signaling the

missing link? Br. J. Dermatol. 2014; 170:1375-1377

Blok JL, Spoo JR, Leeman FW, Jonkman MF, Horvath B. Skin-tissue sparing excision with

electrosurgical peeling (STEEP): a surgical treatment option for severe hidradenitis suppurativa

Hurley stage II/III. J Eur Acad Dermatol Venereol. 2015: 29:379-382

Blok JL, van Hattem S, Jonkman MF, Horvath B. Systemic therapy with immunosuppressive

agents and retinoids in Hidradenitis suppurativa: a systematic review. Br J Dermatol

2013;168:243-252

151

Blok JL, Reesink-Peters N, Diercks GF, Reyners AK, Terra JB. Vulvair basaalcelcarcinoom met

destructieve gevolgen. Ned Tijdschr Geneeskd 2012;156:A5391

JL Blok, PJ Coenraads. Orale retinoïden bij chronisch handeczeem: de effectiviteit van

alitretinoïne. Nederlands Tijdschrift voor Dermatologie en Venereologie 2010;20:680-4

JL Blok, JR Spoo, MF Castellanos-Nuijts, KF van Duinen. Impetigo herpetiformis. Nederlands

Tijdschrift voor Dermatologie en Venereologie 2010;20:401-4

De Groot AC, Blok J, Coenraads PJ. Relationship between formaldehyde and quaternium-15

contact allergy. Influence of strength of patch test reactions. Contact Dermatitis

2010;63:187-91

152

cURRIcULUM VITAE Janine Dickinson-Blok werd geboren op 11 juli 1984 te Deventer. In 2002 behaalde zij haar

VWO diploma aan de Scholengemeenschap “De Waerdenborch” te Holten en koos zij

voor de studie Bewegingswetenschappen aan de Rijksuniversiteit Groningen nadat zij was

uitgeloot voor de studie Geneeskunde. In 2003 was het lot haar beter gezind en kon zij

starten met Geneeskunde in Groningen. Nadat zij in 2008 haar artsen bul behaalde kreeg ze

een aanstelling als arts-onderzoeker op de afdeling Dermatologie in het Universitair Medisch

Centrum Groningen. Tijdens deze onderzoeksperiode richtte zij zich onder begeleiding van

Prof. P.J. Coenraads op handeczeem en allergisch contacteczeem. In juli 2010 begon zij met de

opleiding Dermatologie in het Universitair Medisch Centrum Groningen. Tijdens de opleiding

bleef zij belangstelling houden voor wetenschappelijk onderzoek. In januari 2012 onderbrak

zij derhalve de opleiding om te starten met haar promotietraject naar hidradenitis suppurativa

onder begeleiding van haar promotor Prof. M.F. Jonkman en co-promotor Dr. B. Horváth. In

juli 2014 hervatte zij haar opleiding en deze zal zij naar verwachting afronden in januari 2017.

Janine trouwde in mei 2013 met Michael Dickinson, met wie zij in Groningen woont.

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