No abstract

Summary Background Differentiation and activation of CD4+ T cells is controlled by various cytokines produced by innate immune cells. We have shown that eosinophils (EOS) have the potential to influence Th1 and Th2 cytokine generation by CD4+ cells, but their influence on IL‐17A (IL‐17) has not been established. Objective The purpose of this study is to determine the effect of EOS on IL‐17 production by lymphocytes. Methods Pre‐activated CD4+ T cells were cultured in the presence of either autologous EOS or EOS culture supernatants. Expression of IL‐17 was determined by real‐time quantitative PCR (qPCR) after 5 h and protein level was measured after 48 h. To determine the effect of allergen‐induced airway EOS on IL‐17, subjects with mild allergic asthma underwent bronchoscopic segmental bronchoprovocation with allergen (SBP‐Ag) after a treatment with an anti‐IL‐5 neutralizing antibody (mepolizumab) to reduce airway eosinophilia. IL‐17 mRNA was measured in bronchoalveolar lavage (BAL) cells by qPCR. Results In vitro, EOS significantly increased IL‐17 production by CD4+ T cells. Addition of exogenous IL‐1ß increased expression of IL‐17 mRNA by CD4+ T cells. EOS expressed and released IL‐1ß. Furthermore, levels of IL‐1ß in EOS supernatants highly correlated with their ability to increase IL‐17 expression by CD4+ T cells, and neutralizing antibody to IL‐1ß reduced expression of IL‐17 mRNA. In vivo, reduction of EOS in the airway using mepolizumab was associated with diminished IL‐17 expression after SBP‐Ag. Conclusions and clinical relevance Our data demonstrate that EOS can promote IL‐17 production through the release of IL‐1ß. Enhanced IL‐17 cytokine production is another mechanism by which EOS may participate in pathogenesis of allergic airway inflammation in asthma.

Conjugated linoleic acid (CLA) has been shown to enhance immune reactions such as lymphocyte blastogenesis and delayed-type hypersensitivity. We investigated the role of CLA in type I (immediate) hypersensitivity, using a guinea pig tracheal superfusion model for measuring antigen-induced airway smooth muscle contraction and inflammatory mediator release. Female Hartley guinea pigs were fed a diet supplemented with 0.25 g corn oil or linoleic acid/100 g of diet (control) or 0.25 g CLA/100 g of diet for at least 1 wk before and during active sensitization to ovalbumin antigen. Tracheae from sensitized guinea pigs were suspended in air-filled water-jacketed (37 degrees C) tissue chambers in a superfusion apparatus. Tracheae were superfused with buffer containing antigen, and tissue contraction was recorded. Superfusate was collected at 90-s intervals for evaluation of histamine and PGE(2) release. CLA did not affect antigen-induced tracheal contractions when expressed as gram contraction per gram tissue. CLA significantly reduced antigen-induced histamine and PGE(2) release. CLA appears to decrease release of some inflammatory mediators during type I hypersensitivity reactions.

BackgroundThymic stromal lymphopoietin (TSLP) and eosinophils are prominent components of allergic inflammation. Therefore, we sought to determine whether TSLP could activate eosinophils, focusing on measuring the regulation of TSLPR expression on eosinophils and degranulation in response to TSLP, as well as other eosinophil activation responses.MethodsEosinophil mRNA expression of TSLPR and IL-7Rα was examined by real-time quantitative PCR of human eosinophils treated with TNFα and IL-5 family cytokines, and TSLPR surface expression on eosinophils was analyzed by flow cytometry. Eosinophils were stimulated with TSLP (with and without pre-activation with TNFα and IL-3) and evaluated for release of eosinophil derived neurotoxin (EDN), phosphorylation of STAT5, and survival by trypan blue exclusion. A blocking antibody for TSLPR was used to confirm the specificity of TSLP mediated signaling on eosinophil degranulation.ResultsEosinophil expression of cell surface TSLPR and TSLPR mRNA was upregulated by stimulation with TNFα and IL-3. TSLP stimulation resulted in release of EDN, phosphorylation of STAT5 as well as promotion of viability and survival. TSLP-stimulated eosinophil degranulation was inhibited by a functional blocking antibody to TSLPR. Pre-activation of eosinophils with TNFα and IL-3 promoted eosinophil degranulation at lower concentrations of TSLP stimulation.ConclusionsThis study demonstrates that eosinophils are activated by TSLP and that eosinophil degranulation in response to TSLP may be enhanced on exposure to cytokines present in allergic inflammation, indicating that the eosinophil has the capacity to participate in TSLP-driven allergic responses.