Protective Mechanism of Epigallocatechin-3-gallate against Helicobacter pylori- induced Gastric Epithelial Cytotoxicity via Blockage of TLR-4 Signaling

Helicobacter pylori infection leads to gastric mucosal damage by several mechanisms including the direct effect of virulence factors produced by H. pylori, propagation of inflammation, oxidative stress, DNA damage, and induction of apoptosis. (-)-Epigallocatechin-3-gallate (EGCG), one of green tea catechins, is known to suppress H. pylori-induced gastritis through its antioxidative and anti-bacterial actions. In this study, we evaluated protective mechanism of EGCG against H. pylori-induced cytotoxicity in gastric epithelial cells. For analyzing EGCG effect on viability of gastric epithelial cells, MTT assay and dye exclusion assay were performed. The degree of DNA damage was evaluated by Comet assay and apoptotic DNA fragmentation assay. To investigate EGCG effect on H. pylori-induced the toll-like receptors 4 (TLR-4) signaling, RT-PCR and western blot analysis corresponding to glycosylated TLR-4 was done. LOX metabolites were measured with RP-HPLC. EGCG pretreatment effectively rescued gastric mucosal cells from the H. pylori-induced apoptotic cell death and DNA damage, and administration of this catechin enhanced gastric epithelial cell proliferation. H. pylori infection stimulated the glycosylation of TLR-4 which initiates intracellular signaling of infected host cell, and then pretreatment of EGCG completely blocked its glycosylation. The blockage of TLR-4 activation by EGCG resulted in inactivation of ERK1/2 and NF-kB as downstream molecules of TLR-4 signaling induced by H. pylori. This disturbance of H. pylori-induced host cell signaling by EGCG attenuated the synthesis of proinflammatory mediators, HETEs. EGCG pretreatment showed significant cytoprotective effects against H. pylori-induced gastric cytotoxicity via interference of TLR-4 signaling induced by H. pylori. Thus, our result implies that continuous intakes of green tea could prevent the deleterious consequences of H. pylori infection.

Author dc:creator

• 이, 기명

Contributors dc:contributor

• 조, 성원
• 대학원 의학과
• 103828

• EGCG
• Helicobacter pylori
• Toll-like receptor-4
• Apoptosis
• ERK1/2
• NF-kB
• 세포사멸

Language dc:language

en

Identifier

http://dcoll.ajou.ac.kr:9080/dcollection/jsp/common/DcLoOrgPer.jsp?sItemId=000000000377
000000000377

OAI identifier oai:identifier

oai:repository.ajou.ac.kr:201003/1394