子宫内膜炎是严重危害奶牛产业经济效益的奶牛常发病，而子宫内膜感染大肠杆菌是本病发生的主要原因之一。前期研究发现，鼠李糖乳杆菌GR-1能够通过抑制NF-κB的激活，抑制大肠杆菌诱导奶牛子宫内膜上皮细胞（BEEC）炎性细胞因子的大量释放，减轻细胞的炎性损伤，但其分子机制尚不明确。在此基础上，本项目拟建立大肠杆菌诱导BEEC损伤模型，以MyD88依赖性和非依赖性信号途径为切入点，结合RNAi方法和特异性信号转导抑制剂，采用流式细胞术、实时荧光定量PCR及免疫印迹等技术，检测细胞凋亡、紧密连接蛋白的表达、TLR4及其下游衔接分子、NF-κB信号通路中关键信号分子的表达情况，探求鼠李糖乳杆菌GR-1抗大肠杆菌诱导BEEC损伤作用，以期阐明鼠李糖乳杆菌GR-1抗大肠杆菌致BEEC炎性损伤的分子机制及其作用靶点，为临床应用乳酸菌治疗奶牛子宫内膜炎提供一定的理论依据。

Endometritis is an important disease of dairy cows that leads to significant economic losses in the dairy cattle industry. Endometrial infection of Escherichia coli is one of the major causes of this disease. Previous research has shown that Lactobacillus rhamnosus GR-1 can inhibite the activation of NF-κB and the release of inflammatory factors induced by Escherichia coli, resulting the reduction of bovine endometrial epithelial cells (BEEC) inflammatory injury. However, the molecular mechanism still remains unclear. Thus, in the present study, BEEC damage model induced by Escherichia coli will be established. Using the MyD88-dependent and independent signaling pathways as an entry point, combined with the RNAi method and specific transduction inhibitors, then the BEEC apoptosis will be detected by flow cytometry, and the expression levels of key signaling molecules in the NF-κB signaling pathway, tight junction proteins, TLR4 and its downstream adaptor molecules will be tested by immunoblot assays and real-time quantitative PCR. Then to explore the effect of Lactobacillus rhamnosus GR-1 on BEEC injury induced by Escherichia coli and explain the molecular mechanism and target of Lactobacillus rhamnosus GR-1 against BEEC inflammatory injury induced by Escherichia coli. Furthermore, this project will contribute significantly to provide a theoretical basis for the clinical application of lactic acid bacteria in the treatment of bovine endometritis.