Beta-carotene inhibits Helicobacter pylori-induced expression of inducible nitric oxide synthase and cyclooxygenase-2 in human gastric epithelial AGS cells.

Reactive oxygen species (ROS) play critical roles in Helicobacter pylori (H. pylori)-associated gastric ulceration and carcinogenesis. Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are involved in H. pylori-induced gastric diseases. Previously we demonstrated that H. pylori in Korean isolates induced the activation of mitogen-activated protein kinases (MAPK) and oxidant-sensitive transcription factors NF-kappaB and AP-1 which mediates the expression of iNOS and COX-2 in gastric epithelial AGS cells. beta-Carotene shows antioxidant activity and inhibits NF-kappaB-dependent gene expression in various cells. Present study aims to investigate whether beta-carotene inhibits H. pylori-induced expression of iNOS and COX-2 by suppressing the activation of MAPK, NF-kappaB, and AP-1 in gastric epithelial AGS cells. HP99 (H. pylori in Korean isolates) was added to AGS cells at the ratio of bacterium/cell, 300/1. beta-carotene inhibited H. pylori-induced increase in ROS level, the activation of MAPK (p38, the c-Jun NH2-terminal protein kinases, the extracellular signal-regulated kinases), NF-kappaB, and AP-1 and the expression of iNOS and COX-2 in AGS cells. Conclusion: beta-carotene inhibits oxidant-mediated activation of inflammatory signaling and suppresses the expression of iNOS and COX-2 in gastric epithelial AGS cells infected with H. pylori.