Eosinophil apoptosis induced by fungal immunomodulatory peptide-fve via reducing IL-5α receptor

Background/Purpose: Eosinophils are important effector cells in the pathogenesis of allergic bronchial asthma. Enhancement of eosinophil apoptosis has been considered to have therapeutic effect on allergic disease. Fungal immunomodulatory peptide (FIP) fve has been reported to possess immunoprophylactic activities for allergic diseases. The purpose of this study was to investigate the modulation of FIP-fve on human eosinophil survival derived from allergic asthmatic patients. Methods: Eosinophils were obtained from allergic asthmatic patients and purified with the use of density gradients and immunomagnetic beads negative selection. Apoptosis was assessed by annexin V and propidium iodide. The apoptotic signal protein, CD95 and IL-5 receptor expression were assessed by Western blot and flow cytometric analysis. Results: When the eosinophils were treated with FIP-fve in the presence of IL-5, IL-5-enhanced eosinophil survival diminished. FIP-fve could reduce IL-5-mediated survival of eosinophils and decrease IL-5Rα expression. In the presence of FIP-fve, CD95 expression was upregulated and Bcl-xL and pro-caspase 3 expression were downregulated in cultured eosinophils. Conclusion: The results suggest that FIP-fve can inhibit IL-5-mediated survival of eosinophils through the modulation of cytokine receptor expression and apoptotic signal protein production. The modulatory effect of FIP-fve on eosinophil apoptosis in vitro indicates that it may have some therapeutic effect on eosinophil-related allergic inflammation in vivo.