Immune-enhancing effect of BCG44 and its supernatant on cyclophosphamide-induced immunosuppressed mice and RAW264.7 cells the modulation of the gut microbiota.

We established a model of cyclophosphamide (CTX)-induced immunosuppressed mice and RAW264.7 cells to assess the effectiveness of BCG44 and its supernatant in enhancing immune function and modulating the gut microbiota. BCG44 and its supernatant restored Th17/Treg balance and alleviated gut inflammation by elevating the expression of interleukin-10 (IL-10) and decreasing IL-6 and toll-like receptor 4 (TLR4). Meanwhile, BCG44 and its supernatant downregulated the levels of lipopolysaccharide and D-lactic acid while increasing the expression of tight junction proteins (ZO-1 and occludin) and goblet cells/crypts to ameliorate mucosal damage. BCG44 and its supernatant may restore the gut microbiota in the immunosuppressed mice by regulating keystone species ( and ). PICRUSt2 function prediction and BugBase analysis showed that  BCG44 and its supernatant significantly down-regulated American trypanosomiasis and potentially_pathogenic. In addition, under normal inflamed culture conditions, stimulation of RAW246.7 cells with BCG44 supernatant activated immune response with increasing proliferation ability and the gene expression of IL-10 while decreasing TLR4. Metabolites in the BCG44 supernatant included arginine, tyrosine, solamargine, tryptophan, D-mannose, phenyllactic acid, and arachidonic acid. Collectively, these findings suggested that BCG44 and its supernatant possess potential immunomodulatory activity and modulate gut microbiota dysbiosis in the CTX-induced immunosuppressed mice.