Lactobacillus paracasei influences the gut-microbiota-targeted metabolic modulation of the immune status of diarrheal mice.

Koumiss is a traditional fermented drink widely consumed by nomads owing to its rich nutritional value and therapeutic effects. Lactobacillus paracasei is a bacterial strain isolated from koumiss and has a positive effect on diarrhea; however, the relationship between gut microbial dysbiosis and L. paracasei gut microbial metabolism remains unclear. Therefore, this study aimed to explore the anti-diarrheal activity of L. paracasei in a murine E. coli-induced diarrhea model to provide novel insights into its probiotic properties by analyzing its intestinal metabolites and effects on the intestinal barrier. Oral administration of the probiotic, L. paracasei, enhanced tight junction protein expression, alleviated clinical manifestations consistent with E. coli-induced diarrhea, and positively affected overall intestinal microecological homeostasis. Moreover, it increased the goblet cell count and the secretory immunoglobulin A content and regulated intestinal metabolism via gut microbes, consequently preventing E. coli-mediated disruption of the intestinal epithelial cell barrier.

Lactobacillus paracasei from koumiss ameliorates diarrhea in mice via tight junctions modulation.

OBJECTIVES: Probiotics are gaining interest as alternative options for antibiotic or antiinflammatory drugs. Probiotics can affect the health of the host through metabolites and competitive inhibition adhesion of pathogenic microorganisms. Koumiss is an important part of the diet of Asian nomads, and is rich in a broad array of probiotics that can benefit the body. Mongolians have developed koumiss therapy to assist in the treatment of various diseases. In the present study, we investigate the beneficial effect of Lactobacillus paracasei, a strain isolated from koumiss, on a mouse model of diarrhea induced by Escherichia coli O8 (E. coli O8). METHODS: Probiotics were isolated from Mongolian koumiss. The resistance of probiotics against acid, bile salts, gastric juice, and intestinal juice was evaluated. The mouse model of diarrhea was established by the intragastric administration of E. coli O8 after NaHCO3 treatment. L. paracasei was intragastrically administered before or after E. coli O8 exposure in mice. The plasma levels of diamine oxidase and zounlin were quantified using an enzyme-linked immunosorbent assay, and the integrity of the intestinal barrier and goblet cells of mice with diarrhea were observed using hematoxylin and eosin and Alcian blue periodic acid-Schiff staining. The expression of tight junction (TJ) proteins was detected by immunohistochemistry and Western blot. RESULTS: A total of five lactic acid bacteria and two yeast strains were isolated from koumiss, and L. paracasei was screened for animal experiments. Experimental results showed that L. paracasei could reduce the increase in diamine oxidase and zonulin caused by E. coli (P < 0.05); increase goblet cells and the expression of TJ proteins ZO-1, occludin, and claudin-1 (P < 0.05); increase the expression of mucin 2, oligomeric mucus/gel-forming (P < 0.05) protein; and reduce the level of inhibitor kappa B-alpha and myosin light-chain kinase. CONCLUSIONS: L. paracasei reduced the intestinal permeability, induced the expression of mucin 2, oligomeric mucus/gel-forming protein, and increased the number of goblet cells in mice by the upregulation of the expression of TJ proteins via the nuclear factor kappa B cells-myosin light-chain kinase signaling pathway.