Lactobacillus casei regulates differentiation of Th17/Treg cells to reduce intestinal inflammation in mice.

In order to study the ability of Lactobacillus casei to ameliorate murine enteritis, 18 mice were randomly divided into 3 groups: the enteritis group, intervention group, and control group. The interleukin (IL)-6 and transforming growth factor-β (TGF)-β content in mouse peripheral blood and duodenum was detected using an enzyme-linked immunosorbent assay (ELISA). The number of CD4+CD25+Foxp3+ T-regulatory cells (Tregs) and CD4+IL-17A+ Th17 cells in the mesenteric lymph nodes (MLN) and spleen were detected using flow cytometry, and quantitative reverse transcription polymerase chain reaction (PCR) and western blot analysis were used to measure Foxp3 and retinoid-related orphan receptor-γ (RORγt) mRNA and protein expression in the MLN. Histological changes in the duodenum were observed. Results indicate that in the intervention group, IL-6 content in mouse peripheral blood and duodenum was significantly lower than in the enteritis group (P < 0.05), while TGF-β content was significantly increased compared to the enteritis group (P < 0.05). For the intervention group, the percentages of CD4+CD25+Foxp3+ Tregs in spleen and MLN were increased (P < 0.05), while the percentages of CD4+IL-17A+ Th17 cells were decreased compared to the enteritis group (P < 0.05). The expression of Foxp3 mRNA and protein in the intervention group was higher than in the enteritis group, while RORγt mRNA and protein were significantly lower (P < 0.05). After mice in the enteritis group were treated with L. casei, duodenal inflammation was relieved. This study demonstrated that L. casei could have possible implications for the enterotoxigenic Escherichia coli (ETEC) induced intestinal inflammation by regulating the ratio imbalance of Th17/Treg cells.