Role of MD-2 in Tool-like receptor 4-dependent signaling in Helicobacter-pylori-associated gastritis

MD-2 在幽门螺杆菌相关胃炎工具样受体 4 依赖性信号传导中的作用

• 批准号: 13670520
• 负责人: ISHIHARA Shunji
• 金额: $ 2.24万
• 依托单位: Shimane Medical University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13670520/
• 关键词: TLR4; MD-2; H.pyvlori; ECL cell; Toll-like receptor; H.Pylori

Helicobacter pylori (H. pylori) lipopolysccharide (LPS) is one of the major virulence factors in the induction of gastritis. LPS-dependent activation of gastric epithelial cells and infiltrating macrophages leads to secretion of several proinflammatory cytokines. However, little is known about the recognition system of H. pylori LPS in gastric mucosal cells. Recent studies have shown that LPS initiates signal transduction through toll-like receptor (TLR)-4, and this pathway is activated by MD-2. The aim of this study is to investigate TRL-4/MD-2 complex-specific recognition of H. pylori LPS in gastric mucosal cells. Gastric antral biopsy samples were taken from patients with and without H. pylori infection. Four gastric cancer cell lines (MKN-7, MKN-28, MKN-45 and AGS) were used for in vitro study. Expression of TLR-4 and MD-2 in gastric biopsy specimens and gastric cancer cell lines was examined by reverse-transcription polymerase chain reaction and western blot analysis. Localization of TLR-4 in histological sections was also evaluated by immunohistochemistry. Luciferase assay was performed for the assessment of H. pylori LPS-induced NF-kB activation in gastric epithelial cells and transient transfectants expressing TLR-4 and/or MD-2. TLR-4 was constitutively expressed in the stomach with and without H. pylori infection and localized in gastric epithelial cells and infiltrating mononuclear cells. However, the expression of MD-2 in H. pylori-positive subjects was higher than that in H. pylori-negative subjects. In vitro, all gastric epithelial cells expressed both TLR-4 and MD-2 and H. pylori LPS stimulated NF-kB activation in these cells. LPS responses in transfectant expressing both TLR-4 and MD-2 was significantly higher than that expressing only TLR-4. TLR-4/MD-2 complex is essential for the recognition of H. pylori LPS and MD-2 may regulate TLR-4-dependent signaling in the development of H. pylori-associated gastritis.

幽门螺杆菌（H. pylori）脂多糖（lipopolyschcharide，LPS）是诱发胃炎的主要毒力因子之一。胃上皮细胞和浸润性巨噬细胞的LPS依赖性活化导致几种促炎细胞因子的分泌。然而，对H.幽门螺杆菌LPS在胃粘膜细胞中的表达。最近的研究表明，LPS通过Toll样受体（TLR）-4启动信号转导，而这一途径被MD-2激活。本研究的目的是研究TRL-4/MD-2复合物对H.幽门螺杆菌LPS在胃粘膜细胞中的表达。胃窦活检标本取自有和无H。幽门感染本研究采用四种胃癌细胞系（MKN-7、MKN-28、MKN-45和AGS）进行体外研究。采用逆转录聚合酶链反应（RT-PCR）和免疫印迹法（Western blot）检测TLR-4和MD-2在胃活检标本和胃癌细胞系中的表达。TLR-4在组织切片中的定位也通过免疫组织化学进行了评价。荧光素酶法检测H.幽门螺杆菌LPS诱导的胃上皮细胞和表达TLR-4和/或MD-2的瞬时转染子中的NF-κ B活化。TLR-4在有和无H. pylori感染，并定位于胃上皮细胞和浸润的单个核细胞。MD-2在H. pylori阳性者高于H.幽门阴性受试者。在体外，所有胃上皮细胞均表达TLR-4和MD-2以及H. pylori LPS刺激NF-κ B活化。在同时表达TLR-4和MD-2的转染子中，LPS应答显著高于仅表达TLR-4的转染子。TLR-4/MD-2复合物是H. pylori LPS和MD-2在H.幽门相关性胃炎

项目成果

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