Immunoregulation of murine immunocytes to Bifidobacteria strain isolated from feces of healthy Korean children: IL-10 release and proportional change of CD4⁺CD25⁺ cells

Bifidobacteria is one of the prototypes of probiotics bacteria, normally inhabitating the intestinal tract of humans. To msearch for a potent immunoregulatory Bifidobacteria strain, we screened the Bifidobacteria strains isolated from the feces of healthy Korean children. The mRNA or protein expression of an anti-inflammatory cytokine, IL-10, from mouse macrophages stimulated with live Bifidobacteria was examined. Of tested strains, Bifidobacteria A28 induced the highest IL-10 gene expression of murine macrophages. To probe immunoregulatory activity of the selected strain on the mice, we evaluated the proportional changes of CD4⁺CD25⁺ surface marker in the murine splenocytes. Flow cytometric analysis showed that the overall percentages of CD4⁺CD25⁺ cells in A28-treated splenocytes were higher than those of untreated splenocytes. In parallel, IL-10 release from A28-treated mouse peritoneal macrophages and splenocytes was significantly higher than that of untreated control cells. Collectively, the Bifidobacteria A28 strain isolated from the feces of healthy Korean children augments the mRNA or protein expression of IL-10 release from mouse peritoneal macrophages as well as the proportion of CD4⁺CD25⁺ cells of naïve splenocytes. These provide in vitro scientific clues that Bifidobacteria A28 might be usable for anti-inflammatory disease such as inflammatory bowel disease (IBD).