Rehmannia glutinosa polysaccharides enhance intestinal immunity of mice through regulating the microbiota

The Rehmannia glutinosa polysaccharides (RGP) have various benefits such as enhancing immune cell activity, decreasing oxidative stress and delaying or inhibiting tumor occurrence. Although much research has been directed at understanding the role of RGP, its influence on gut immunity is largely understudied. Here, we aimed to dissect the immune-regulating effects of RGP in the mice intestines. In vivo experiments involving the oral administration of RGP to mice at dosages of 100, 200, and 400 mg/kg over seven consecutive days revealed that RGP therapy significantly increased the percentages of CD3⁺ T lymphocytes and CD19⁺ B lymphocytes in intestines and improved the integrity of the mucosal barrier. Moreover, RGP modified the gut microbiota composition by enhancing the abundance of beneficial bacteria like Lactobacillus and Akkermansia. Fecal microbiota transplantation (FMT) experiments further revealed that RGP modulated the host's intestinal immunological function by altering the gut microbiota composition. These findings indicate that RGP may control the immunological function of the intestines.