Effect of Lactobacillus fermentum to alleviate symptoms of DSS-induced inflammatory bowel disease

Abstract

We identified and evaluated immunometabolic functions of novel Lactobacillus fermentum strains (KBL374, KBL375) isolated from healthy Korean stools. When human peripheral blood mononuclear cells PBMCs were treated with these L. fermentum KBL374 or KBL375 strains, pro-inflammatory cytokines such as IL-2, IFN-γ, IL-4, and IL-17A etc were reduced and anti-inflammatory cytokine such as IL-10 were elevated. When these strains were orally administered into DSS-induced colitis mice model, both L. fermentum KBL374 and KBL375 showed beneficial effects in terms of colon length, cecum weight and histological scores. As consistent with PBMC data in human, both L. fermentum KBL374 and KBL375-treated mice demonstrated reduced Th1-, Th2- and Th17-type cytokine levels and increased IL-10 levels compared to DSS control group in the colon. In addition, administration of L. fermentum KBL374 or KBL375 in mice increased CD4+CD25+Foxp3+Treg populations in MLN. Furthermore, both L. fermentum KBL374 and KBL375 were demonstrated to modulate the innate immune response by improving gut barrier functions and reducing leukocyte infiltration. In addition to regulate the immune response, the administration of L. fermentum KBL374 or KBL375 reshaped and increased the composition of diversity of gut microbiota. In particular, L. fermentum KBL375 increased abundance of beneficial microorganisms such as Lactobacillus spp. and Akkermansia spp. We observed through the results of this study that both L. fermentum KBL374 and KBL375 alleviate inflammatory diseases such as IBD in the gut by regulating immune responses and altering the composition of gut microbiota and metabolite.