Diphenyleneiodonium inhibits the activation of mitogen-activated protein kinases and the expression of monocyte chemoattractant protein-1 in Helicobacter pylori-infected gastric epithelial AGS cells.

OBJECTIVE: To investigate whether NADPH oxidase induces MCP-1 expression and the activation of mitogen-activated protein kinases (MAPKs) in H. pylori-infected gastric epithelial cells. MATERIAL: H. pylori in Korean isolates, human gastric epithelial AGS cells TREATMENT: AGS cells pretreated with or without an NADPH oxidase inhibitor diphenyleneiodonium (DPI) are cultured in the presence of H. pylori at a bacterium/cell ratio of 300:1. METHODS: Reactive oxygen species (ROS) and MCP-1 were determined by confocal microscopy and enzyme-linked immonosorbent assay. NADPH oxidase activity was measured by lucigenin assay. mRNA expression of MCP-1 was analyzed by reverse transcription-polymerase chain reaction. Levels of MAPKs were assessed by Western blot analysis. RESULTS: H. pylori induced increase in ROS, NADPH oxidase activity, MCP-1 expression, and the activation of MAPKs including extracellular signal-regulated kinases, p38, and jun N-terminal kinases in AGS cells, which was inhibited by DPI. CONCLUSION: Inhibiting NADPH oxidase by DPI suppresses H. pylori-induced activation of MAPKs and MCP-1 expression in AGS cellsope