Modulating effects of a functional food containing Dendrobium officinale on immune response and gut microbiota in mice treated with cyclophosphamide

National Herbal Drink (NHD) is a functional food approved by the State Administration for Market Regulation for immune enhancement. In this study, the effects of NHD on Cyclophosphamide (CTX)-induced immune regulation and gut microbiota dysregulation in mice were investigated to elucidate whether the attenuation of immunosuppression was related to the regulation of the gut microbiota by NHD. Our study showed that CTX induced immune organ damage in immunosuppressed mice, with reduced levels of serum immunoglobulins IgG, IgM, and complement C3 and disruption of bone marrow hematopoiesis, accompanied by changes in liver toxicity and shortened colonic length. However, all these changes were reversed to varying degrees by NHD intervention. Delayed-type hypersensitivity (DTH) and serum hemolysins in mice also indicated that NHD could effectively regulate cellular and humoral immunity in the body. In addition, it is noteworthy that NHD can also improve intestinal pathology, elevate the expression of intestinal tight junction proteins Occludin and Claudin-1 to restore intestinal barrier function. Furthermore, alpha-diversity and beta-diversity analysis showed that NHD has a positive regulatory effect on the gut microbiota. At the phylum level, NHD could regulate the abundance of three major phyla, namely, Bacteroidetes, Firmicutes, and Actinobacteriota. At the species level, the abundance of the beneficial genus uncultured_bacterium_g__norank_f__ Muribaculaceae increased and the abundance of the harmful genus unclassified_f__Lachnospiraceae decreased after the NHD intervention. These results provide evidence that NHD modulates the immune response in cyclophosphamide-induced immunocompromised mice by restoring intestinal barrier function and regulating gut microbiota disorders.