E-1 Role of IgE and IgE receptors in allergic airway inflammation and remodeling Ruby Pawankar, MD, Ph.D. FRCP, FAAAAI Prof. Div of Allergy, Dept of Pediatrics Nippon Medical School Tokyo, Japan pawankar.ruby@gmail.com
The Allergic Inflammatory Cascade B Cell Plasma Cell Mast Cell Second Allergen Exposure IgE Cytokines IL-4, IL-13 IgE crosslinked by allergen Antigen Presenting Cell T Cell First Allergen Exposure AR and Asthma Symptoms & Exacerbation Histamine Leukotriene Prostaglandins Cytokines Mast Cell Degranulation
Mast cells can induce IgE synthesis in B cells NMC (PAR) (n=8) T cell (PAR) (n=3) NMC +ail-4 (n=5) NMC +ail-13 (n=5) T cell + ail-4 (n=5) T cell + ail-13 (n=5) < 2 < 2 1 2 T otal IgE (ng/ml) 3 Ag IgE FceRI IL-4/ IL-13 Mc CD4L CD4 B CD4-CD4L IgE class switch sige Pawankar R et al. J Clin Invest Pawankar R et al, Clin Exp Allergy Pawankar R. Curr Opin Allergy Immunol,
IgE is locally produced in the target organ CD2+ IL-4+ IgE Ce mrna+ CD2 + Durham et al. Eur Resp J
Binding of IgE to high-affinity (FceRI) receptor Twenty-five years later the receptors that mediate the binding of IgE to cells were described. Allergen binding site Ce1 V H C L V L IgE Although FceRI is expressed on monocytes and dendritic cells (and other cell types), its expression level is 1-1 fold less than in mast cells and basophils. FceRI Ce2 Ce3 a 2 a 1 Ce4 out Cell membrane a b g g in Holgate ST. QJM 1998
Fc epsilon RI expression in NMC % 1 ** 8 6 4 2 Pawankar R et al J Clin Invest, 1997 PAR CIR
E-7 High-affinity IgE receptor-bearing cells in atopic and non-atopic asthma FcεRIα mrna+ cells (x 1 6 cells) obtained from 12mL BAL 17 FcεRI+ cells/mm 2 18 p=.1 p=.6 16 3 p=.2 15 12 9 p=.6 2 6 1 3 Saline Allergen Saline Allergen Atopic Non-atopic Atopic Non-atopic Asthmatics Controls Asthmatics Controls Rajakulasingam K. Am J Respir Crit Care Med 1998 Humbert M. Am J Respir Crit Care Med 1996
pg/ ml pg/ ml IL-4 + IgE enhance mediator release from NMC 1 pg/ ml histamine release (%) 9 8 7 6 5 4 3 1 ** ** ** 5 4 3 2 1 ** ** IL-6 ** CIR (fr eshly isolated) CIR untreated & sensitized IL-4+IgE-treated & sensitized ** p <.1 3 25 2 15 1 5 ** ** ** 5 4 3 2 1 ** ** Pawankar R Clin Exp All IL-4 IL-13
Mast cell-ige-ige receptor axis Mc Ag IgE Mc Ag Ag Mc IL-4 Ag Mc
The prevalence of asthma is related to the level of serum IgE standardized for age and sex Prevalence of asthma (%) 4 Age 6 to <35 years n =2657 of the general population with self-reported asthma or allergic rhinitis 3 Age 35 to <55 years Age 55+ years 2 1 < 1.5 1.5 <.5.5 <.5.5 <1.5 1.5+ In all age groups, there was Ranges a highly of serum significant IgE Z score trend for prevalence to increase with increasing Z scores (p<.1). Burrows B et al. N Engl J Med 1989
FceRI-mediated Thymic Stromal Lymphopoietin Production by IL-4-primed Human Mast Cells E-11
Function of Thymic stromal lymphopoietin (TSLP ) E-12 Induction of T H 2- attracting chemokines CCL17, CCL22 Promotion of development of B22+ IgM+ immature B cells from pre-b cells Priming of naïve T H 2 cells to produce T H 2 cytokines A weak comitogen for T cell proliferation CD4+T cell development
TSLP as a key initiator of allergic inflammation TSLPR KO mice fail to develop an inflammatory lung response to inhaled antigen. E-13 Humans TSLP is expressed in epithelial cells of patients with atopic dermatitis The number of cells within the bronchial epithelium and submucosa expressing mrna for TSLP are significantly increased in asthmatics as compared with controls. Mice Skin-specific overexpression of TSLP results in an atopic dermatitis-like phenotype. Lung-specific overexpression of TSLP induces asthmalike airway inflammation.
TSLP expression by human bronchial mucosal mast cells of asthmatic patients TSLP Lumen Merged Tryptase (mast cells)
Significant increase in number of TSLP + Tryptase + cells in the airways of asthmatic patients A 4 3 2 *** 1 Control Asthma B 1 8 6 4 2 C 4 *** 3 2 1 Control Asthma D 2 15 1 5 *** F Control Asthma 6 5 4 3 2 1 *** Control Asthma G 6 5 4 3 2 1 Atopic * Non-Atopic
I-39 (ng/ml) TSLP (pg/ml) TSLP production by human mast cells following aggregation of FceRI in the presence of IL-4 1 b) IgE+IL4 wash Anti-IgE with DMSO -48h IgE+IL4 wash wash with DMSO Anti-IgE with PIC 16 h c) 4 3 2 1 ** * * a-ige - + d) a- IgE 2 15 1 5 - +
Correlation of % of TSLP + cells in mast cells with the serum IgE level, and hyperresponsibility in asthmatic patients and controls 1 8 r 2 =.131 P =.48 1 8 r 2 =.252 P =.24 6 6 4 4 2 2.5 1 1.5 2 2.5 3 3.5 4 5 1 15 2 IgE (U/ml) log1 Acetylcholine (mg/ml)
The number of AREG + tryptase + cells increases in bronchial mucosa of subjects with asthma
Correlation between AREG + tryptase + cells with the extent of goblet cell hyperplasia in the airways of asthmatic subjects Mucus score= n 1 + 2n 2 Grade 1 Goblet cell height epithelial layer <(1/3) Grade 2 Goblet cell height epithelial layer>1/3 n 1 ; Grade 1-cell count n 2 ; Grade 2 cell count (Tokuyama K et al Am J Physiol 199)
Rationale for anti-ige therapy Anti-IgE stops IgE binding to effector cells Allergen IgE synthesis Mast cell degranulation Inflammatory mediators Clinical symptoms Allergic rhinitis Mechanism Asthma Atopic eczema, urticaria Food allergy Treatment Allergen avoidance Hyposensitization Mast-cell stabilization: cromones, isoprenaline Mediator antagonists: antihistamines, antileukotrienes Late-phase inhibitors: steroids Adapted from Roitt J. Essential Immunology 1994
Immunohistochemical staining of bronchial biopsy specimens before (left) and after (right) 16 weeks of omalizumab treatment. Representative sections show staining with antibody against: ECP (A and B) Cell-surface IgE (C and D) High-affinity IgE R (E and F) IL-4 (G and H) Djukanović R, et al. Am J Respir Crit Care Med 24;17:583-93.
Mechanisms of Action of Omalizumab Reduces serum levels of free IgE Down-regulates expression of IgE receptors (FceRI) on mast cells and basophils. In the airways of patients with allergic asthma, it reduces FcεRI+ and IgE+ cells and causes a profound reduction in tissue eosinophilia, together with reductions in submucosal T-cell and B-cell numbers. Holgate S, Casale T, Wenzel S, Bousquet J, Deniz Y, Reisner C. J Allergy Clin Immunol 25;115(3):459-65.
Mechanisms of action of omalizumab (cont d) The reductions in circulating levels of IgE resulting from omalizumab treatment leads to reductions in FceRI expression on mast cells, basophils and dendritic cells. This combined effect results in attenuation of several markers of inflammation, including peripheral and bronchial tissue eosinophilia, levels of GM-CSF, IL-2, IL-4, IL-5 and IL-13. It may also reduce allergen presentation to T- cells and the production of Th2 cytokines. Holgate S, et al. Allergy 29:64(12):1728 36.
Forced expiratory volume in 1 second as a percentage of baseline in the placebo (A) and omalizumab (B) groups. van Rensen E, et al. Allergy 29;64:72 8.
Effect of add-on therapy with omalizumab in patients with severe persistent asthma whose asthma was inadequately controlled by therapy with high-dose ICSs plus a LABA Humbert M, et al. Allergy 25; 6:39 16
Conclusion Benefits of Anti-IgE in atopic disease E-26 Effectively reduces the incidence of allergic asthma exacerbations while decreasing the need for steroids Improves asthma-specific QoL and reduces the incidence of hospitalizations Can simplify the control of asthma with only once or twice monthly injections Controls the symptoms of SAR, reducing the requirement for concomitant medication Has a good long-term safety profile
WAO White Book on Allergy Allergic Diseases as a Global Public Health Issue Authored by: International expert allergists and clinical immunologists; has been compiled for publication under the supervision of the WAO Education Council. Purpose: To serve as a major resource in explaining allergic diseases, their prevalence, management, and the importance of adequate service provision for allergy patients. Edited by Professors Ruby Pawankar, Stephen T. Holgate, G. Walter Canonica, and Richard F. Lockey http://www.worldallergy.org/userfiles/file/wao-white-book-on-allergy_web.pdf
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