DA-9601, a standardized extract of Artemisia asiatica, blocks TNF-alpha-induced IL-8 and CCL20 production by inhibiting p38 kinase and NF-kappa B pathways in human gastric epithelial cells

Abstract

AIM: TO investigate whether, or how, DA-9601, which is a new gastroprotective agent, inhibits TNF-alpha-induced inflammatory signals in gastric epithelial AGS cells. METHODS: Cell viability was determined by MTT assay. IL-8 and CCL20 promoter activities were determined by a luciferease reporter gene assay. NF-kappa B-dependent transcriptional activity was determined by I-kappa B alpha degradation, NF-kappa B p65 nuclear translocation and a luciferase activity assay. IL-8 and CCL20 gene expression and protein secretion were determined by RT-PCR and an enzyme-linked immunosorbent assay (ELISA). Total and phosphorylated forms of mitogen-activated protein kinases (MAPKs) were determined by Western blot. RESULTS: Treatment of AGS cells with DA-9601 reduced TNF-alpha-induced IL-8 and CCL20 promoter activities, as well as their gene expression and protein release. TNF-alpha also induced NF-kappa B-dependent transcriptional activity in AGS cells. In contrast, in cells treated with DA-9601, TNF-alpha-induced NF-kappa B activity was significantly blocked. Although all three MAP kinase family members were phosphorylated in response to TNF-alpha, a selective inhibitor of p38 kinase SB203580 only could inhibit both NF-kappa B-dependent transcriptional activity and IL-8 and CCL20 production, suggesting a potential link between p38 kinase and NF-kappa B-dependent pathways in AGS cells. Interestingly, DA-9601 also selectively inhibited p38 kinase phosphorylation induced by TNF-alpha. CONCLUSION: DA-9601 blocked TNF-alpha-mediated inflammatory signals by potentially modulating the p38 kinase pathway and/or a signal leading to NF-kappa B-dependent pathways in gastric epithelial cells. (C) 2006 The WJG Press. All rights reserved.