肠出血性大肠杆菌O157:H7 TCCP调节宿主肠上皮细胞抗感染免疫作用研究

The interaction between pathogen and host dentermines the outcome of infection. The host intestinal mucosal immune responses play an important role in the anti-infection process. Enterohemorrhagic Escherichia coli O157: H7 (O157) , an important zoonotic infectious pathogent, is able to inhibit the immune responses of intestinal epithelial cells, which help escape the killing of the host and lead to diarrhea, hemorrhagic colitis, hemolytic uremic syndrome and other serious diseases. A lot of evidence showed that TCCP (translocated intimin receptor-coupled cytoskeletal protein) of O157 was translocated into host cells by type III secretion system, which assist the bacteria to escape host destruction via inhibiting anti-bacterial immunity. However, its mechanism is unclear. This study was to designed to construct the TCCP eukaryotic expression vector and tccp deletion mutant cells, and to analyze the effects of TCCP on mediating anti-O157 infection in vitro organ culture model and animal models. Besides this project will furthur uncover the protein interactions in the signal transloduction pathway of TCCP, and identify the molecules that interated with TCCP. The aim of this project is to clarify the mechanism of the TCCP's modulating host innate immune mechanisms, and to provide theoretical guidance for new bacteria prevention method and new therapeutic targets.

病原体和宿主的相互作用是决定感染的关键，宿主肠道粘膜免疫反应在抗感染免疫中发挥重要作用。作为重要的人畜共患传染病病原菌，肠出血性大肠杆菌 O157:H7（O157）能够抑制宿主肠上皮细胞粘膜免疫反应，逃逸宿主的杀伤作用，导致腹泻、出血性结肠炎、溶血性尿毒综合征等严重疾病。诸多证据表明O157的毒力因子TCCP(内膜素受体偶联细胞骨架蛋白)可通过细菌的Ⅲ型分泌系统注入宿主肠上皮细胞，抑制宿主抗O157的肠粘膜免疫反应来辅助细菌逃逸宿主的杀伤而介导抗感染免疫效应，但其机制尚不清楚。本研究拟构建TCCP真核表达载体和tccp缺失突变株，通过细胞、体外器官培养和动物模型，在分析TCCP介导宿主上皮细胞抗O157感染免疫作用的基础上，研究TCCP与促炎因子调控信号通路蛋白的相互作用，筛选鉴定与之作用的效应分子，以阐明TCCP发挥调节宿主天然免疫的作用机制，为寻找该菌感染的预防和治疗靶点提供理论指导。