leupeptins and Eosinophilia

Interleukin-25 (IL-25) is a novel T-helper-2 (Th2) cytokine of the IL-17 family that plays a key role in allergic inflammation. Recent studies reported that over-expression of IL-25 in mouse induces eosinophilia. We investigated the effect of IL-25 on the expression of several adhesion molecules on human eosinophils and the underlying intracellular mechanisms.. Viability of eosinophils was measured by annexin V-fluorescein isothiocyanate (FITC) assay. Gene expression and surface expression of intercellular adhesion molecule (ICAM)-1 (CD54), ICAM-3 (CD50), L-selectin (CD62L), leukocyte function-associated antigen (LFA-1) (CD11a/CD18) and very late antigen-4 (VLA-4, CD49d/CD29) on eosinophils were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and flow cytometry, respectively. Adhesion of eosinophils to fibronectin was assessed using the fibronectin-coated insert system.. Viability of eosinophils was significantly enhanced by IL-25 from 41% to 76% dose-dependently. IL-25 could significantly upregulate the surface expression of ICAM-1, but suppress those of ICAM-3 and L-selectin on eosinophils in a dose-dependent manner. Adhesion of eosinophils to fibronectin was also significantly enhanced by IL-25. Besides, pre-incubation with p38 mitogen-activated protein kinases (MAPK) inhibitor SB203580, C-Jun NH2-terminal protein kinases (JNK) inhibitor SP600125 and proteosome inhibitor MG-132 could significantly restrain the effects of IL-25 on surface expression of L-selectin, ICAM-1 and ICAM-3, respectively, and also on the adhesion of eosinophils onto fibronectin (all P < 0.05).. Our findings suggest an essential role of IL-25 in enhancing survival and regulating surface expression of ICAM-1, ICAM-3 and L-selectin on human eosinophils through the activation of p38 MAPK, JNK and nuclear factor (NF)-kappaB pathways, thereby shedding light on the molecular mechanisms of IL-25-induced eosinophilia in allergic inflammation.

Topics: Apoptosis; Cell Adhesion; Cell Adhesion Molecules; Cells, Cultured; Cysteine Proteinase Inhibitors; Enzyme Inhibitors; Eosinophilia; Eosinophils; Gene Expression Regulation; Humans; Hypersensitivity; Imidazoles; Inflammation; Interleukin-17; Interleukins; JNK Mitogen-Activated Protein Kinases; Leupeptins; NF-kappa B; p38 Mitogen-Activated Protein Kinases; Pyridines; RNA, Messenger