Microbiome-metabolome responses of Fuzhuan brick tea crude polysaccharides with immune-protective benefit in cyclophosphamide-induced immunosuppressive mice

The present study investigated the immune-protective effect of polysaccharides from Fuzhuan brick tea (FBTPs) in cyclophosphamide (Cy)-induced immunosuppressive mice. The results showed that high-dose of FBTPs administration remarkably alleviated Cy-evoked immune damage through improving the body features, organ indices, immune responses and oxidative stress in the mice. Further microbiota analysis revealed that FBTPs obviously restored Cy-evoked microbial dysbiosis by increasing several beneficial bacteria Lactobacillus, Allobaculum, Unclassified_f_Lachnospiraceae and norank_f_Lachnospiraceae, while reducing Bacteroides, norank_f_Ruminococcaceae, Colidextribacter, Alloprevotella, norank_f_Desulfovibrionaceae and Helicobacter. Meanwhile, metabolomics analysis found that FBTPs significantly altered a range of microbial metabolites, including inosine, deoxyinosine, taurine, sinapic acid, maltotriose, butyric acid, lysophosphatidyl cholines (LysoPCs), lysophosphatidic acids (LysoPAs) and choline. These altered metabolites were involved in purine metabolism, ABC transporters, sulfur metabolism, neuroactive ligand-receptor interaction, biosynthesis of phenylpropanoids, carbohydrate digestion and absorption, protein digestion and absorption, choline metabolism in cancer and glycerophospholipid metabolism pathways, which were mainly related to immune responses, antioxidant capacity and energy supply of the immunosuppressive mice. Additionally, some significant correlations were observed between the specific microbiota and effective metabolites. These results provide a novel insight into the immune-protective effect of FBTPs on regulating the intestinal microbiota and metabolism, which are helpful for thoroughly understanding the nutrition of FBTPs and providing a solid basis for the deeper utilization of Fuzhuan brick tea (FBT).