Bifidobacterium breve CCFM1310 enhances immunity in immunosuppressed mice via modulating immune response and gut microbiota

There has been a rising interest in studying how Bifidobacterium breve can affect the immune system over the years. The aim of this study was to evaluate the effect of B. breve on the immune system and to explore the mechanism in a mouse model of cyclophosphamide (CTX)-induced immunosuppression. The results of the study showed that B. breve CCFM1310 significantly increased the thymus index (p<0.05), promoting the secretion of immunoglobulins and the number of immune cells in the blood. Moreover, B. breve CCFM1310 could repair the spleen injury. It increased the mRNA expression level of T-bet (p<0.05) and decreased the mRNA expression level of TGF-β and FOXP3 (p<0.05). B. breve CCFM1310 alleviated oxidative stress by increasing enzymatic activities of SOD, CAT and T-AOC and reducing the concentration of MDA. Moreover, it repaired intestinal damage by increasing the number of goblet cells, upregulating mRNA expression of tight junction proteins, and promoting the production of short-chain fatty acids (SCFA). B. breve CCFM1310 could regulate the gut microbiota by increasing the relative abundance of Lactobacillus (p<0.05) and decreasing the relative abudance of Lachnospiraceae NK4A136 group. Overall, our study suggests that B. breve CCFM1310 could enhance immunity in CTX-induced immunosuppressed mice by affecting immune responses, oxidative stress and gut microbiota.