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Background In human basophils from different subjects, maximum IgE-mediated histamine release and the level of syk protein expression correlate well. Recent studies suggest that in some patients treated with omalizumab, the response to stimulation with anti-IgE antibody increases. In unrelated studies, there is also evidence that the composition of FcεRI in basophils differs among subjects. This observation raised the possibility that the stoichiometry of FcRβ:FcεRIα is not fixed to 1:1 and might be modifiable during changes in the basophil environment. Objective To determine if treatment with omalizumab results in increases in syk expression, anti-IgE-mediated histamine release and disproportionately alters the relative presence of FcRβ and FcεRIα. Method Syk, FcεRIα, and FcRβ expression was monitored during the treatment of subjects with omalizumab. Results Treatment with omalizumab reduced histamine release from peripheral blood leukocytes stimulated with cat-allergen in vitro, but histamine release stimulated with anti-IgE antibody increased 2 fold. Expression of syk increased 1.86 fold. There was no change in the expression of c-cbl, a signaling element that is sensitive to the presence of IL-3, and no increase in response to FMLP, a response that also increases in the presence of IL-3. There was a 60% decrease in the FcRβ:FcεRIα ratio in patients treated with omalizumab. Conclusions In the context of previous studies, these studies provide support for a proposal that syk expression is modulated in vivo by an IgE-dependent mechanism and that the ratio of FcεRI alpha and beta subunits in basophils is influenced by factors extrinsic to the cell.

Eosinophilic esophagitis (EoE) is a recently recognized inflammatory disorder that needs a potential therapeutic strategy. We earlier showed that iNKT cell-deficient mice are protected from allergen-induced EoE. Therefore, we now tested the hypothesis that iNKT cells are induced in the human EoE and is a novel possible target for the treatment of human EoE. Accordingly, we examine number of iNKT cells and eosinophils and expression of iNKT-associated cell surface receptors and chemokines by performing immunofluorescence, qPCR and ELISA in the esophageal biopsies and blood samples of normal subjects (comparison control) and EoE patients. Herein, we show that iNKT cell number, their receptor subcomponents Vα24 and Vβ11 expression, and associated chemokine CXCL16 levels (or expression) are induced significantly in EoE patients compared with normal individuals. In addition, we show that CXCL16 levels (or expression) correlate with the mRNA levels of Vα24 receptor but not well with esophageal eosinophilia in human EoE. Of note, we show that in vivo activation of iNKT cells is sufficient to induce EoE in mice. Furthermore, we show that anti-mCD1d- and anti-hVα24Jα18-neutralizing antibody treatment protects allergen-induced experimental EoE. Taken together, we have shown first time that iNKT cells have a critical pathogenic role in human and experimental EoE. iNKT cell neutralization by humanized anti-CD1d and anti-Vα24Jα18 antibodies might be a novel and potential therapy for human EoE.

Food allergy is one of the major causes that promote EoE; therefore, we tested the hypothesis that IL-18 is involved in food allergen-induced EoE pathogenesis. Accordingly, we examined normal SPT+ and SPT− EoE patient blood and biopsy samples for IL-18, IL-18Rα, ICAM and VCAM expression Herein, we show increased IL-18 level is highly significant in food allergen SPT+ compared to SPT− EoE patients. We also report that IL-18Rα+ cells and mRNA levels are induced in the esophageal biopsies of EoE patients and blood IL-18 levels correlate with esophageal eosinophilia (p<0.01). Additionally, we report that the levels of esophageal eosinophil and mast cells correlate with ICAM expression in human EoE. Mechanistically, we show that IL-18 in vitro stimulates iNKT cells and endothelial cells and induce eosinophil active cytokines IL-5, IL-13. We provide the evidence that IL-18 is critical cytokine involved in activation of iNKT cells and ICAM in promoting human EoE..

Growing evidence suggests that anaphylatoxins, C3a and C5a, play important roles in innate immunity and may also participate in the pathogenesis of asthma. Previous studies with animal models and immunohistochemistry analysis of lung tissue indicated that anaphylatoxins may regulate airway hyperresponsiveness (AHR) in asthma via the activation of their cell surface G protein-coupled receptors (C3aR and C5aR) in airway smooth muscle (ASM) cells. Using RT-PCR, flow cytometry, and confocal microscopy, we made the surprising observation that while C3aR and C5aR were expressed in human mast cells, they were not present in cultured primary human or murine ASM cells. Furthermore, we could not detect C3aR in smooth muscle-positive cells of human trachea or bronchus. Interestingly, incubation of human mast cells with ASM cells, but not its culture supernatant, caused a significant enhancement of C3a-induced mast cell degranulation. Although stem cell factor (SCF) and its receptor c-kit are constitutively expressed on ASM cells and mast cells, respectively, neutralizing antibodies to SCF and c-kit failed to inhibit ASM cell-mediated enhancement of mast cell degranulation. However, dexamethasone-treated ASM cells were normal for cell surface SCF expression but were significantly less effective in enhancing C3a-induced mast cell degranulation when compared with untreated cells. These findings suggest that cell-cell interaction between ASM cells and mast cells, via a SCF-c-kit-independent but dexamethasone-sensitive mechanism, enhances C3a-induced mast cell degranulation, which likely regulates ASM function, thus contributing to the pathogenesis of asthma.