Abstract: Objective To 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. Methods SD 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. Results Intestinal 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. Conclusion The 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.