Effect of Bifidobacterium animalis subsp. lactis XLTG11 on Immune Function and Intestinal Flora in Cyclophosphamide-Immunosuppressed Mice

To investigate the effect of Bifidobacterium animalis subsp. lactis XLTG11 (XLTG11) on immune function and intestinal flora in cyclophosphamide (CTX)-immunosuppressed mice.

Altogether 60 mice were randomly divided into five groups: blank, model, low-dose, medium-dose and high-dose XLTG11 groups. The blank group was injected intraperitoneally with normal saline from day 1 to 3, and the other groups 100 μL of CTX solution (40 mg/kg) to establish an immunocompromised mouse model. From day 4 to 30, the low-, medium- and high-dose XLTG11 groups were given 0.2 mL of XLTG11 suspensions at doses of 2.5 × 10⁶, 2.5 × 10⁷ and 2.5 × 10⁸ CFU/animal, respectively, and both blank and model groups 0.2 mL of normal saline/animal. Body mass, immune organ index, delayed-type metamorphosis, proliferation of splenic lymphocytes, T-lymphocyte subpopulation, natural killer (NK) cell activity, phagocytic activity of peritoneal macrophages, cytokine levels, intestinal flora structure, and short-chain fatty acids (SCFA) were detected in each group of mice.

XLTG11 increased the immune organ index, foot-plantar thickness, splenic lymphocyte proliferation, T lymphocyte subsets CD4⁺ and CD8⁺, NK cell activity and macrophage phagocytosis activity, and cellular immune factors (interleukin (IL)-6, IL-10, IL-1β and interferon (IFN)-γ) in immunosuppressed mice. In addition, XLTG11 alleviated intestinal tissue damage caused by CTX, regulated the intestinal flora and increased intestinal SCFA (acetic, propionic and butyric acid) levels.

XLTG11 could significantly enhance the immune function and regulate the intestinal flora of mice.