Phospholipase D1 is important in Der f 2 induced IL-13 expression in human bronchial epithelial cells

초록

The purpose of this study was to identify the role of PLD1 in Der f 2 induced IL-13 expression. PLD activity was increased within 5 min after exposure of Der f 2, the major house dust mite allergen, in human bronchial epithelial cell line (BEAS-2B). Der f 2 treatment resulted in translocation of PKC-α to membrane from cytosol. When we blocked PKC-α and p38 MAP kinase with their specific inhibitors, Der f 2- induced PLD activation was completely abolished. These results indicated that PKC-α and p38 MAP kinase acts as upstream activator of PLD in Der f 2-induced BEAS-2B cells. Furthermore, expression of IL-13 increased by Der f 2 treatment was blocked by inhibition of PKC-α and p38 MAP kinase, respectively. The results suggest that expression of IL-13 was related to PKC-α / p38 MAP kinase pathway in Der f 2 treated BEAS-2B cells. When we blocked PLD1 activity with PLD1 siRNA, Der f 2-induced IL-13 expression was decreased, suggesting that PLD1 also involved in the expression of this cytokine. Moreover, we detected activation of ATF-2, which regulates gene expression of cytokines, in Der f 2 treated BEAS-2B cells. Der f 2 treatment elevated phosphorylation of ATF-2 within 5 min. To confirm the involvement of ATF-2 in IL-13 expression, cells were transfected with ATF-2 siRNA. Knockdown of ATF-2 blocked the expression of IL-13 induced by Der f 2 treatment. Taken together, PLD1 acts as important regulator in Der f 2-induced IL-13 expression through PKC-α/p38 MAP kinase pathway. Also, ATF-2 might be one of the transcriptional factors of IL-13 expression in Der f 2 treated BEAS-2B cells.