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!