Probiotics the Good Neighbor: Guarding the Gut Mucosal Barrier

Problem statement: The disruption of gut barrier function plays a crucial role in the pathogenesis of not only gastrointestinal diseases, but also the diseases of liver and other organs. Mucosal protective factors that preserve the gut barrier integrity are beneficial in the prevention and treatment of such diseases. Probiotics is a group of helpful bacteria that protect the gastrointestinal mucosa from a variety of insults. Therefore, understanding the mechanism of probiotic-mediated protection of gut barrier function is an important area of investigation. Approach: Several studies had addressed the role of probiotics in the protection of gut barrier integrity. In a recent study, we investigated the role of Lactobacillus rhamnosus GG and two soluble proteins, p40 and p75, in the protection of gut barrier function in Caco-2 cell monolayer, a model of the intestinal epithelium. Results: Studies demonstrated that live or dead Lactobacillus rhamnosus GG prevents oxidative stress-induced disruption of tight junctions and barrier function in Caco-2 cell monolayers. The isolated soluble proteins of this probiotic, p40 and p75, also prevent hydrogen peroxide-induced tight junction disruption. This protective effect of probiotic proteins was mediated by the activation of ERK1/2 and protein kinase C isoforms, PKCβI and PKCε. Conclusion: Lactobacillus rhamnosus GG prevent oxidative stress-induced disruption of intestinal epithelial tight junctions and barrier function, suggesting that preservation of epithelial barrier function is one of the mechanisms involved in the mucosal protective role of probiotics in the gut.