OBJECTIVETo investigate MUC2 expression in rat colons induced by probiotics and its effects on the inhibition of E.coli K1 (E44) penetration of the intestinal barrier by probiotics.

METHODSSD rats were subjected to intragastric administration of probiotics, E44, or probiotics +E44 on a daily basis for 7 days, and MUC2 expression in the colons was determined by RT-PCR. MUC2-targeted shRNA (shRNA MUC2) and scrambled shRNA plasmids (shRNA NC) were respectively transfected into Lovo cells, and the efficiency of MUC2 knockdown was determined using qRT-PCR. Competitive exclusion assay was used to evaluate the effects of the probiotics against E44 adhesion and invasion.

RESULTSIntestinal MUC2 mRNA expression was up-regulated in the rats after intragastric administration of probiotics, while E44 administration caused significantly lowered MUC2 expression. MUC2 expression was down-regulated (by 66.7%) by transfection with shRNA MUC2 in Lovo cells as compared with the negative control and mock control cells. The inhibition of E44 adherence and invasion by probiotics was significantly attenuated in transfected Lovo cell culture (in which the relative adhesion and invasion rates of E44 were 56.64% and 66.64%, respectively) as compared with those in the control group.

CONCLUSIONThe up-regulation of MUC2 in rat colons can be one of the mechanisms of the probiotics in antagonizing the translocation of the pathogenic bacteria. Silencing MUC2 expression causes attenuated inhibitory effect of the probiotics on E. coli K1 penetration across human intestinal epithelial cells.