Proinflammatory effects and molecular mechanisms of interleukin-17 in intestinal epithelial cell line HT-29

AIM:To evaluate the proinflammatory effects and molecular mechanisms of interleukin(IL)-17 in intestinal epithelial cell line HT-29.METHODS:HT-29 cells were cultured with IL-17,tumor necrosis factor(TNF)-α,or the combination of both IL-17 and TNF-α.Real-time PCR and Western blot were used to measure the gene expression levels of neutrophil chemokines CXCL1,CXCL2,CXCL5,CXCL6,IL-8and TH-17 cell chemokine CCL20,the phosphorylation levels of p38 and TNF-α,and the expression level of IL-8,after using the p38 inhibitor in HT-29 cells.The stable Act1 knockdown HT-29 cell line was established to further test the phosphorylation changes of p38,after using IL-17 and TNF-α.RESULTS:After HT-29 cells were cultured with IL-17and TNF-α,the expression levels of neutrophil chemokines(CXCL1,CXCL2,CXCL5,CXCL6,IL-8)and Th17chemokine(CCL20)significantly improved(24.96±2.53,28.47±2.87,38.08±2.72,33.47±2.41,31.7±2.38,44.37±2.73,respectively),and the differences were all statistically significant(P<0.01).Western blot results showed that IL-17 obviously enhanced the phosphorylation level of p38,which was induced by TNF-α.Compared with the control group,the expression level of IL-8 significantly declined(9.47±1.36 vs 3.06±0.67,P<0.01)when TH-29 cells were cultured with IL-17and TNF-α.p38 inhibition assay showed that the p38pathway played an essential role in the inflammatory response induced by IL-17.p38 phosphorylation levels could not be changed after using IL-17 and TNF-αin the stable Act1 knockdown HT-29 cell line.CONCLUSION:IL-17 significantly promoted the gene expression levels of TNF-α-induced neutrophil chemokines and Th17 cell chemokine.It is obvious that IL-17and TNF-αhave synergistic effects on p38.