Administration of Enterococcus faecium strain HS-08 increases intestinal acetate and induces IgA secretion in mice.

A probiotic is considered a live microbial feed supplement that has beneficial effects on the host. In this study, the probiotic property by which Enterococcus faecium strain HS-08 strengthens the immune system was investigated. Using a murine model, we evaluated the abilities of this strain to increase intestinal short-chain fatty acid contents and to induce the production of mucosal immunoglobulin A (IgA), which are crucial for mucosal immune systems. Various amounts (0, 0.0038%, 0.038%, or 0.38%) of strain HS-08 cells were administered to BALB/cAJcI mice, which resulted in a dose-dependent increase of fecal IgA levels. A qRT-PCR analysis of Peyer's patch cells revealed that the gene expression of retinal-dehydrogenase, IL-6, B cell-activating factor, and a proliferation-inducing ligand were increased, which lead to IgA secretion via a T-cell-independent mechanism. The administration of 0.038% and 0.38% of strain HS-08 cells also increased fecal acetate levels, which plays important role for maintaining immune functions. This cecal floral analysis and the stability of strain HS-08 against gastrointestinal digestion suggest that this strain can inhabit the host intestine. In conclusion, the administration of Enterococcus faecium strain HS-08 increased intestinal acetate levels and enhanced IgA secretion, which may result in strengthening of the mucosal immune system.