Probiotic Fermentation of Astragalus membranaceus and Raphani Semen Ameliorates Cyclophosphamide-Induced Immunosuppression Through Intestinal Short-Chain Fatty Acid-Dependent or -Independent Regulation of B Cell Function.

Probiotic fermentation can promote the release of more effective components from traditional Chinese medicines (TCMs). Astragalus membranaceus (Fisch.) Bunge (A. membranaceus) and Raphani Semen are TCMs that have gained attention for their immunoenhancing activities. This study aimed to investigate the effects and underlying mechanisms of probiotic-fermented A. membranaceus and Raphani Semen (PROAS) in cyclophosphamide (CTX)-induced immunocompromised mice. Changes in the composition of A. membranaceus and Raphani Semen after fermentation by probiotic strains, including Bifidobacterium longum SD5219, Lactobacillus fermentum NCIMB5221, and Lactobacillus paracasei SD5219, were identified using high-performance liquid chromatography. The immunostimulatory effects and mechanisms of PROAS were evaluated in immunosuppressed mice 3 and 7 days after CTX treatment. Probiotic fermentation of TCMs resulted in changes in major bioactive components. PROAS supplementation effectively restored intestinal integrity in CTX-treated mice by upregulating the mRNA expression of the tight junction proteins. PROAS significantly ameliorated the reduction in the spleen index and number of B lymphocytes caused by CTX treatment and regulated the secretion of cytokines in serum and colon tissues. PROAS administration modulated gut microbial dysbiosis and short-chain fatty acid (SCFA) content in CTX-treated mice. These results suggest that PROAS enhances B lymphocyte function by increasing the regulation of intestinal microbiota to produce high levels of SCFA, repairs the intestinal barrier damage induced by CTX, and promotes intestinal mucosal immunity.