乳酸菌对肠上皮细胞侵袭性大肠杆菌损伤的保护作用

Protective role of Lactobacillus plantarun in regulating intestinal epithelial cells response to pathogenic bacteria

目的:研究肠上皮细胞(Caco-2)在侵袭性大肠杆菌(enteroinvasive Escherichia coli,EIEC)感染后,紧密连接(TJ)相关蛋白表达的改变及乳酸菌对Caco-2细胞的保护作用机制.方法:将Caco-2感染模型分为正常组、感染组、乳酸菌处理组和庆大霉素处理组.采用免疫金标记及电镜观察上皮细胞间TJ的位置和超微结构.免疫荧光观察TJ相关蛋白(Claudin-1,Occludin,JAM-1,ZO-1)及F-actin的表达分布和超微结构变化.结果:紧密连接结构位于相邻上皮细胞间的顶端,间隙大小约25-38nm.EIEC感染后,免疫胶体金定位不清,细胞骨架F-actin遭到破坏,相邻Caco-2细胞间TJ结构遭到破坏,TJ相关蛋白(Claudin-1蛋白,Occludin蛋白,JAM-1蛋白,ZO-1蛋白)的表达亦减少,而乳酸菌处理后F-actin的表达明显增多,可减轻EIEC引起的TJ结构受损,TJ相关蛋白的表达增多.结论:EIEC感染导致Caco-2细胞细胞骨架F-actin、TJ相关蛋白的表达和分布发生改变.乳酸菌可以明显抑制EIEC引起的单层细胞TJ结构和相关蛋白的破坏,并改善细胞骨架的分布表达.

AIM： To investigate the alteration of intestinal epithelial tight junction proteins after infection with enteroinvasive Escherichia coli and to study mechanism underlying protective effect of Lactobacillus plantarun on Caco-2 cells. METHODS： Caco-2 models were established and divided into normal group, infection group, Lactobacillus treatment group and gentamicin treatment group. Ultrastructure of tight junction structure was observed using immuno-gold labeling. The distribution and structure of tight junction proteins, such as Claudin-1, Occludin, ZO-1, JAM-1 as well as F-actin were examined using immunofluorescence assay.RESULTS： The tight junction structure was at the top of intestine epithelial cells. After infection with EIEC, the structure of tight junction was destroyed and the expression of F-actin and tight junction proteins （such as Claudin-1, Occludin, JAM-1, ZO-1） were diminished. But Lactobacillus plantarun prevented induced by EIEC. damage CONCLUSION： The Lactobacillus plantarun exerts a protective effect against the damage to the F-actin and distribution of TJ proteins promoted by enteroinvasive Escherichia coil infection.