Fuzi polysaccharides improve immunity in immunosuppressed mice by regulating gut microbiota composition

Fuzi is a traditional Chinese medicine, and polysaccharides therein are considered the most bioactive compounds, with immunomodulatory effects. However, the mechanisms underlying these effects have not been evaluated. This study assessed the effects of Fuzi polysaccharides (FPS) on the gut microbiota and immune function of mice immunosuppressed with cyclophosphamide (CP). The results showed that PFS increased the concentration of acetic acid, propionic acid, isobutyric acid, and n-butyric acid in the cecum of treated mice. FPS decreased the relative abundance of Helicobacter , Anaerotruncus , Faecalibacterium , Lachnospira , Erysipelotrichaceae _UCG-003, Mucispirillum , and Mycoplasma and increased the relative abundance of Rhodospirillales , Ruminococcaceae _UCG-013, Mollicutes _RF39, Ruminococcus _1, Christensenellaceae _R-7_group, and Muribaculaceae in the gut. Furthermore, FPS increased the spleen and thymus indexes and the number of white blood cells and lymphocytes. CP decreased the relative mRNA expression of NF-кB, IL-6, and iNOS, the differentiation of CD4 + FOXP3 + regulatory T cells, and the protein expression of occludin and zonula occludens-1, whereas FPS reduced these effects. Pearson correlation analysis indicated that the gut microbial composition was significantly correlated with inflammatory gene expression and intestinal barrier function.