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 (M-w) of the purified EPS from L. casei ranged from 2.7 x 10(6) Da to 1.7 x 10(7) Da, and the average M-w was approximately 8.4 x 10(6) 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.