鼠李糖乳杆菌调节仔猪肠顶膜Cl-/OH-交换及肠上皮紧密连接的分子机制

Piglet diarrhoea is always one of the main problems in the pig industry. The mortality of piglets due to diarrhoea is up to 10%-20%，especially Enterotoxigenic Escherichia coli(ETEC) is a major cause of Escherichia coli (E.coli) diarrhoea in piglets. Diarrhoea is closely related with the changes of apical Cl-/OH- exchange activity and the structure of tight junctions in intestinal epithelial cells infected with pathogens,which are regulated via intracellular protein kinase and nuclear factor-kappaB (NFkappaB) signalling pathways. It is demonstrated that Lactobacillus rhamnosus GG (LGG) appears efficacious for preventing ETEC-induced diarrhoea in piglets. However, the mechanisms of LGG affecting electrolyte absorption and the structure and barrier function of tight junctions in intestinal epithelial cells are not fully defined. Our objective in the present study is to reveal the molecular mechanisms of LGG regulating apical membrane Cl-/OH- exchange and tight junctions in piglet intestinal epithelial cells via investigating: 1) the effect of LGG and/or ETEC on intestinal epithelial apical membrane Cl-/OH- exchange activity and the structure of tight junctions; 2) the possible intracellular protein kinase signalling pathway (MAPK or PI3K) being involved in; 3) the influence of LGG on the NFkappaB pathway and the cytoprotection of LGG against oxidative stress in intestinal epithelial cells. The study can provide scientific basis for rational use of LGG in the pig industry.

仔猪腹泻一直是困扰养猪业的重大难题。腹泻仔猪死亡率高达10%-20%，尤其是肠毒性大肠杆菌(ETEC)在仔猪大肠杆菌性腹泻中占重要地位。致病菌引起的肠顶膜Cl-/OH-交换活性及肠上皮紧密连接(TJ)结构改变与腹泻发生密切相关，并受到胞内蛋白激酶和核转录因子的调控。鼠李糖乳杆菌（LGG）能有效降低仔猪ETEC腹泻发病率。然而，有关LGG对肠道电解质吸收及紧密连接结构和屏障功能方面的影响及其作用机制目前仍不清楚。本项目旨在通过研究：1) LGG和/或ETEC对肠顶膜Cl-/OH-交换活性及肠上皮细胞紧密连接结构的影响；2）LGG发挥作用可能的胞内蛋白激酶信号传导通路（MAPK抑或PI3K）；3) LGG对NFkappaB途径的影响及其对肠上皮细胞氧化应激损伤的保护作用，揭示LGG调节仔猪肠顶膜Cl-/OH-交换及肠上皮紧密连接的分子机制，为养猪业合理利用LGG提供科学依据。

仔猪腹泻一直是困扰养猪业的重大难题。腹泻仔猪死亡率高达10%-20%，尤其是肠毒性大肠杆菌(ETEC)在仔猪大肠杆菌性腹泻中占重要地位。致病菌引起的肠顶膜Cl-/OH-交换活性及肠上皮紧密连接(TJ)结构改变与腹泻发生密切相关，并受到胞内蛋白激酶和核转录因子的调控。鼠李糖乳杆菌（LGG）能有效降低仔猪ETEC腹泻发病率。然而，有关LGG对肠道电解质吸收及紧密连接结构和屏障功能方面的影响及其作用机制目前仍不清楚。本项目的实施，通过建立体内、体外模型，通过检测和分析促炎细胞因子、抗炎细胞因子、趋化因子、TLRs、紧密连接蛋白变化规律，以及对IkappaB 降解和NF-kappaB活化分析，初步阐明了仔猪肠道上皮细胞对病原菌固有免疫应答的分子机制。截止目前，项目相关研究工作已发表SCI收录论文9篇。