Colonization and immunoregulation of Lactobacillus plantarum BF_15, a novel probiotic strain from the feces of breast-fed infants.

Immunodeficiency is a manifestation imbalance in the immune system, often during unhealthy states. In recent years, lactic acid bacteria have been found to be important components of the body's innate immune system, and indispensable to maintaining normal immune function. In this study, we evaluated the specific strainLactobacillus plantarum BF_15, a novel strain isolated from the feces of breast-fed infants, which has shownpotentialas an immunomodulator in vitro, by its ability to colonize murine intestines and protect against immunosuppression. Results did indeed support this notion, showing thatBF_15did colonize murine intestines well, and could still be detected in mice feces 14 days after administration of the probiotic was stopped. Moreover, BF_15was found to protect mice against reduction in the levels of several immune-related indicators, includingthe thymus and spleen indexes, splenic lymphocyte proliferation, toe swelling, serum hemolysinformation,and macrophage phagocytosis indexes, triggered by high-dose (200 mg/kg)intraperitoneal administration of CTX. In addition, the bacteria were also found to effectivelybalance intestinal microbiota disorders in the mice. Collectively, these results indicatedthat L. plantarum BF_15can not only successfully colonize murine intestines, but also can effectively alleviate CTX-induced immunosuppression, once established, by rebalancing the intestinal flora. This, therefore,provides strong evidence for the view that BF_15 has the potential to become a highly effective immunomodulating probiotic in human microflora as well.