Self-amplification Mechanisms of Mast Cell activation:

a Hypothesis of Allergy

The First Affiliated Hospital of Nanjing Medical University

China

Shaoheng He

South Korea-Japan-China

Joint Symposium 2012

Part A: Sensitization of mast cells is a key event for allergy;

Part B: Self-amplification mechanisms of mast cell activation;

Part C: Self-amplification mechanisms of mast cell

accumulation;

Outline of my talk:

From Wikipedia, the free encyclopedia: An allergy is formally called type I

(or immediate) hypersensitivity. Allergic reactions are distinctive because of

excessive activation of mast cells and basophils by IgE.

Current definition of allergic diseases：a group of diseases largely driven

via IgE-dependent mechanisms ( Barnes, 2009 ).

The diseases include: allergic rhinitis, allergic asthma, allergic dermatitis,

allergic conjunctitis, anaphylaxis, food or drug allergic reactions etc.

What is allergy?

Part A:

Sensitization of mast cells is a key event

for allergy

Classic pathogenesis of allergy

Mast cells are

primary effector

cells of allergy

IL-4 and -13

sIgE (messenger)

IL-4

Allergen

Histamine, Tryptase

LTC4, PGD2

MHCII

TCR

mIgE

Sensitization phase

Effection phase

MC

B cells

DC

Th

2

Acute anaphylaxis

Asthma, Urticaria

Rhinorrhea, Conjunctivitis

IL-5

IL-5

Eos

MBP, LT, et al.

Chronic anaphylaxis

Prolonged gasping

Eczema

Causitive factors: allergen (officer)

Messengers: sIgE etc. (mail man)

Primary effector cells: mast cells or basophils (soldiers )

Key factors in allergy

All cells and molecules involved in transmiting allergen’s bio-

message to effector cells: They are middle men carrying order

to actors!

Major messengers include sIgE, sIgG, IL-4, IL-13, Th2 cells, B

cells;

Some of them may be used as diagnosing tools for allergy.

Messengers of allergy: sensitization process of allergy

Table 1 Key molecules related to sensitization of mast cells

Mast cells (MC), basophils

(Bas), eosinophils (Eos),

epithelial cells (EC),

macrophages (Mac)

Table 2 Key cells related to sensitization of mast cells

Dendritic cells (DCs), epidermal

Langerhans cells (LCs), T helper (Th),

regulatory T cells (Treg)

Only sensitized mast cells can cause allergic reactions

TLR

少量炎症因子释放

FcεRI

高敏状态

？？

过敏原IFN-lam1

IFN-lam2?

？？

哮喘缓解期促炎因素

？？

LPS等

细菌病毒

TLR

脱颗粒

呼吸道感染

过敏原

TLR

FcεRI

正常情况下

少量炎症因子释放

Part B: Self-amplification mechanisms of

mast cell activation

Asthmatic BALF mast cells exhibit 100-fold increased sensitivity to IgE dependent stimulation

compared with the mast cells from non-asthmatic controls

BALF (●), lung (■) or colon ( ▲)

Dissection Chopping Digestion Separation

Challenge

Loading Measurement

Activation of PAR-2

The hypothesis of self-amplification mechanism of mast cell

degranulation in gut

Allergen

mIgE

TLR

Bacterial or

Virus products

MC

Degranulation

PAR

mIgG

C3aR

C5aR

Protease Allergen

LMWM

Fc RI ε

Fc RI γ C3a

C5a A2AR

Adenosine

Cytokines

CK-R

Table 3 Induction of mast cell activation by known mast cell secretory

products. Compound Known target Released product

Tryptase PAR-2 Granule products, cytokines

Histamine H1 and H4 receptors Granule products, cytokines

IL-3 Specific receptors Granule products, cytokines, LTC4

IL-4 and IL-13 IL-4Ralpha LTC4, Th2 cytokines

IL-29 Cytokines

PGF2alpha Specific receptors Cytokines

GM-CSF Specific receptors Cytokines

Degranulation

TLR

Allergen

Bacterial or

Virtus products

ε

mIgE

mIgG FcRI

FcRI

?

?

?

Potential interactions between mast cell receptors

Mast cells release 3 groups of mediators:

1. Preformed granule products such as histamine, tryptase,

chymase and heparin;

2. Newly synthesized arachidonic acid products such as LTC4 and

PGD2;

3. Cytokines including preformed ones such as TNF, IL-4, IL-13,

and others such as eotaxin and IL-5.

?

Lipid enzyme

Fc RI ε

Ag

IgE

PI(4,5)P2

Lyn Fyn

Protein kinase

LAT

Lipid messengers

Adaptor

Degraduation

Syk

PI(4,5)P2 PI(3,4,5)P3

DAG

Btk

IP3

PKC Ca2+

ROS

PI(3)K

Gene transcription

Ras

MEK

Erk

PLA2

NFAT NF B κ

Akt

Transcription factor

Rac

MEKK

Jnk

CRAC

TRPC

IP3R

Ca2+

Grb2

AA

PGs

LTs

PAF

Ca2+

Cytokines

Stored?

Newly

synthesized?

Cytokines

Ros

ER

PLC-γ

PI(3)K Gab2

Jnk p38

Table 4. Proinflammatory actions of major mast cell products

LPS = lipopolysaccharide; MMP = matrix metalloproteinase; TNF = tumor necrosis factor; RANTES = regulated

upon activation normal T cell expressed and secreted; GM-CSF = granulocyte/macrophage colony-stimulating factor;

TSLP = thymic stromal lymphopoietin; PAF = platelet-activating factor; PGD = prostaglandin D; LTC = leukotriene

C; DC = dendritic cell; IL = interleukin; NA = not available.

Mast cells and basophils: respond to allergen challenge and

release their inflammatory mediators to cause pathological

damage and clinical manifestation. Actors

Symptoms of allergy occur only after mast cells or basophils

being activated.

Theoretically, degranulation of mast cells and basophils is the

definitive event in allergy.

Primary effector cells of allergy

Activators of mast cells include IgE-dependent, IgG-dependent

(J Allergy Clin Immunol. 2005), Toll like receptor agonists, complement

C3a, C5a or low molecular weight molecules such as Sodium

sulfite (Ann Allergy Asthma Immunol. 2006), fMLP, Monoterpenes (Planta

Med. 2011), diesel exhaust particles (J Allergy Clin Immunol. 2002), etc.

Part C: Self-amplification mechanisms of

mast cell accumulation

Accumulation of mast cells in the peritoneum of mouse

Influence of compound 48/80 on mast cell accumulation in the peritoneum of mice

Influence of tryptic enzymes on mast cell accumulation in the peritoneum of mice

Skin

Colon

Tonsil

Tryptase + IL-29 Chymase + IL-29

Lung

Figure2.

Double labeling

immunohistochemical

staining of IL-29 in

human mast cells. Cells

stained with G3 or B7

antibody only were in

red (solid arrow heads),

with SC1 antibody only

were in brown (open

arrow heads) and double

labeled with G3 and

SC1 antibodies or B7

and SC1 antibodies were

in brown and red

(arrows).

Table 5. Number of IL-29 containing cells in foreskin, colon, tonsil and lung

tissues stained by anti-human tryptase antibody G3 and anti-human IL-29

antibody SC1 with a double labeling immunohistochemical technique

Tissue

Positive stained cells

G3/mm2 SC1/mm2 G3 and SC1/mm2 % G3 positive

cells expressing

IL-29

Foreskin 3.0 (0.7 – 5.8) 2.5 (0.6 – 5.1) 58.7 (27 – 120) *† 95 (94 – 97)

Colon 5.0 (0.5 – 15.8) 5.9 (0.4 – 28.8) 70.4 (55.8 – 121) *† 95 (78 – 99)

Tonsil 4.5 (0.7 – 6.5) 2.2 (0.2 – 8.2) 34.7 (8.6 – 129) *† 96.5 (92 – 99)

Lung 10.2 (6.0 – 14.7) 2.2 (0.8 – 8.0) 18.4 (11.1 – 37.3) *† 88 (82 – 99)

Data shown are the median (range) value from 6 different donors. Positively stained cells

in at least 30 fields ( 400 magnification) of each section were counted. * P < 0.05 in

comparison with the cells stained by G3 antibody alone. † P < 0.05 in comparison with the

cells stained by SC1 antibody alone (paired Mann-Whitney U-test).

IL-29 induces mast cell accumulation in the

peritoneum of mice A

B

IL-6, IL-3,

SCF

Histamine, PAF,

Tryptase, Eotaxin,

RANTES, MCP-1,

TNF, SCF,

IL-8, IL-29, IL-6

pMC

Endothelial cells

Adhesion molecule

Blood vessel

Transmembrane migrationChemotactic receptor

Mature MC

In-tissue migration

In-tissue proliferation ?SCF

Chemotactic productsfrom MC

Stem cells

In-tissue migration

?

?

Induction of mast cell accumulation by mast cell products

1、Hofstra CL, et al. Histamine H4 receptor mediates chemotaxis and

calcium mobilization of mast cells. J Pharmacol Exp Ther, 2003,

305(3):1212-1221.

2、 Kushnir-Sukhov NM, et al. 5-hydroxytryptamine induces mast cell

adhesion and migration. J Immunol, 2006, 177(9):6422-6432.

3、 Di Girolamo N, et al. Human mast cell-derived gelatinase B (matrix

metalloproteinase-9) is regulated by inflammatory cytokines: role in

cell migration. J Immunol, 2006, 177(4):2638-2650.

4、 Induction of mast cell accumulation by mast cell chymase (unpublished

data).

Induction of mast cell accumulation by mast cell products

1. We have demonstrated sensitization of mast cells is a key event for

allergy, which involves numerous cells and molecules;

2. We have proposed self-amplification mechanisms of mast cell activation;

3. We have proposed self-amplification mechanisms of mast cell

accumulation;

4. We propose a revised pathogenesis of allergy

In summary

PAR2

Paracrine

Paracrine

Histam

ine?

H1

receptor

Anti-Ig

E

Tryptase

?

IL-3IL-4GM-CSF

Ca2+?

Paracrine

Cytokine receptor

PAR2

Paracrine

Paracrine

Histam

ine?

H1

receptor

Anti-Ig

E

Tryptase

?

IL-3IL-4GM-CSF

Ca2+?

Paracrine

Cytokine receptor

pMC

Endothelial cells

Blood vessel

Transmembrane migration

MC

products

In-tissue migration

TLRMC

PAR

C3aR

C5aR

Fc RIε

Fc RIγ

A2AR

CK-R

Histamine,

PAF,

Tryptase,

Eotaxin,

RANTES,

MCP-1,TNF,

SCF,IL-8,

IL-29,IL-6

Activator

Allergicreaction

EosinophilNeutrophilAmplification mechanism

(+) (+)

Thank you for

your attention！