15-deoxy-Δ12,14-prostaglandin J2 suppresses NADPH oxidase activity in Helicobacter pylori - infected gastric epithelial cells

Dept. of Medical Science/박사[한글] H. pylori는 소화성 궤양, 위선암 및 위림프종 발생의 위험인자로 인식되고 있으며, 소화성 궤양의 중요 병인으로 알려져 있다. 본 연구에서는 활성산소의 증가와 이의 주요 생성 원천인 NADPH oxidase의 활성이 H. pylori에 의한 염증성 신호 전달의 활성과 싸이토카인 생성에 관여하는지 보고자 하였다. 또한 H. pylori에 의해 유도된 염증체계를 억제할 수 있는 치료제로 최근에 류마티스 관절염에 사용되고 있는 PPAR-γ 리간드인 15d-PGJ2의 효과를 기대해 보았다.연구 결과 H. pylori로 자극한 위상피세포주인 AGS 에서 NADPH oxidase를 매개로 한 활성산소의 증가, 주요 염증성 신호기전 중 하나인 Jak/Stat의 인산화의 증가, 및 싸이토카인인 CCL5의 생성 증가가 관찰되었다. 또한 HSP90β siRNA를 이용한 HSP90β의 발현 억제 연구를 통하여 HSP90β가 NADPH oxidase의 활성에 결정적인 요인으로 작용하는NADPH oxidase의 세포질 내 인자인 Rac의 활성 및 세포막 이동을 조절함을 관찰하였다. 그리고 15d-PGJ2가 H. pylori로 유도된 Jak/Stat활성과 CCL5의 생성을 억제하였으며, 이의 항염증 작용기전은 HSP90β과 Rac의 상호작용을 억제함으로써 NADPH oxidase 활성 및 이를 매개로 한 활성산소의 생성 억제를 통하여 그 효과를 나타냄을 확인하였다.본 연구를 통하여 15d-PGJ2가 H. pylori에 의해 유도된 염증 억제에 유익할 것으로 판단된다. [영문]Helicobacter pylori (H. pylori) plays an important role in the pathogenesis of chronic gastritis, peptic ulcer, and gastric adenocarcinoma. Reactive oxygen species (ROS) are one of the potent toxic factors in H. pylori-induced gastric injury. The epithelial cytokine/chemokine response, associated with ROS, is important in the early stages of H. pylori-induced inflammation. 15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) has been suggested to have an anti-inflammatory action by reducing inflammatory cytokines. This study was aimed to investigate in H. pylori-infected gastric epithelial AGS cells 1) whether H. pylori-activated NADPH oxidase mediates Jak/Stat signaling through ROS production, 2) whether H. pylori-activated Rac1, a NADH oxidase subunit, is mediated by HSP90β, and 3) whether 15d-PGJ2 shows anti-inflammatory effects by suppressing HSP90β-mediated NADPH oxidase activation.As a result, H. pylori-induced ROS production was inhibited by NADPH oxidase inhibitor, DPI. H. pylori-induced phosphorylation of Jak1/Stat3 and expression of inflammatory cytokine CCL5 were inhibited by both DPI and Jak/Stat3 inhibitor, AG490. H. pylori induced membrane translocation of HSP90β and direct interaction of Rac1 with HSP90β. Furthermore, HSP90β siRNA suppressed H. pylori-induced NADPH oxidase activation and ROS production as well as Rac1 activation.In addition, the treatment of 15d-PGJ2 suppressed H. pylori-induced NADPH oxidase activation, ROS production, Jak1/Stat3 phosphorylation, and CCL5 expression. 15d-PGJ2 also inhibited membrane translocation of HSP90β and activation of Rac1.In conclusion, 15d-PGJ2 acts as an anti-inflammatory effector through inhibition of NADPH oxidase activity and might ameliorate the H. pylori-induced gastric inflammation.prohibitio

Expression of suppressors of cytokine signaling-3 in Helicobacter pylori-infected rat gastric mucosal RGM-1cells

Our previous studies show that Helicobacter pylori (H. pylori) induces oxidative stress and the expression of proinflammatory cytokines in gastric epithelial cells. H. pylori induces the expression of molecular chaperones and proteins involved in protein-folding machinery as a defense mechanism against cellular stress. The suppressors of cytokine signaling (SOCS) are known as negative regulators of major immune signal pathways. The purpose of this article is to determine whether H. pylori in a Korean isolate (HP99) induces the expression of SOCS in rat gastric mucosal RGM-1 cells as a defense mechanism. As a result, HP99 induced SOCS-3 expression time-dependently in RGM-1 cells. SOCS-1 was not expressed while SOCS-2 expression was not changed by HP99 infection in RGM-1 cells. SOCS-3 might have a defensive role in H. pylori-infected gastric mucosal cells. Further study by manipulating SOCS-3 gene should be performed to investigate the physiological meaning of SOCS-3 induced by H. pylori in gastric mucosal cellsope