Exopolysaccharide Produced by Lactobacillus casei Promotes the Differentiation of CD4+ T Cells into Th17 Cells in BALB/c Mouse Peyer's Patches in Vivo and in Vitro.

The immunomodulatory activity of a few Lactobacillus exopolysaccharides (EPS) has been reported. However, whether Lactobacillus EPS can promote the differentiation of CD4 T lymphocytes (CD4+T) cells into T-helper 17 cells (Th17 cells) in the Peyer's Patches (PPs) of mice has not been addressed. In this study, we found the molecular weight (Mw) of the purified EPS from L. casei ranged from 2.7 × 106 Da to 1.7 × 107 Da, and the average Mw was approximately 8.4 × 106 Da. In healthy BALB/c mice, EPS elevated the numbers of Th17 cells and levels of Th17-related cytokines. In vitro, EPS induced BMDCs to stimulate the differentiation of CD4+T cells of PPs into Th17 cells and the related cytokine secretions. Results suggest that L. casei EPS can effectively induce and promote the differentiation of CD4+T cells of PPs into Th17 cells in healthy mice and has the potential ability to improve intestinal mucosa immunity.