[The postbiotic HM0539 from Lactobacillus rhamnosus GG prevents intestinal infection by enterohemorrhagic E. coli O157: H7 in mice].

OBJECTIVE: To assess the protective effect of the novel postbiotic HM0539 from Lactobacillus rhamnosus GG against intestinal infection by enterohemorrhagic E. coli O157: H7.
METHODS: We performed adhesion and invasion experiments to evaluate whether HM0539 could block E. coli O157: H7 adhesion to HT-29 cells. The expressions of mucin2 and the tight junction proteins ZO-1 and Occludin in HM0539-treated HT-29 cells were analyzed using immunofluorescence assay and Western blotting. Animal experiments were conducted in mice to observe the survival rate and changes in body weight, intestinal morphology and the intestinal barrier function after the challenge and HM0539 treatment.
RESULTS: HM0539 significantly inhibited the adhesion and invasion of E. coli O157: H7 to HT-29 cells in a dose-dependent manner. HM0539 treatment 4 h prior to E. coli O157: H7 challenge significantly lowered the adhesion and invasion rates of bacteria as compared with the treatment administered at the same time of challenge (P < 0.05). E. coli O157: H7-induced down-regulation of mucin2 and tight junction proteins in HT-29 cells was obviously alleviated by HM0539 treatment of (P < 0.05). In the animal experiment, HM0539 treatment significantly inhibited body weight loss (P < 0.05), alleviated jejunal injury, and inhibited E. coli O157: H7-induced destruction of jejunal goblet cells in the challenged mice (P < 0.05). HM0539 also significantly up-regulated the expression of mucin2 and ZO-1 proteins in the jejunum of E. coli O157:H7-infected mice (P < 0.05).
CONCLUSIONS: HM0539 not only inhibits the adhesion and invasion of E. coli O157: H7 to HT-29 cells, but also enhances the resistance against E. coli O157: H7 infection in mice by attenuating the destruction of mucin and tight junction proteins.