Fermentation of Ganoderma lucidum and Raphani Semen with a probiotic mixture attenuates cyclophosphamide-induced immunosuppression through microbiota-dependent or -independent regulation of intestinal mucosal barrier and immune responses

Abstract

Background: Probiotic fermentation is a promising strategy for improving the nutritional and functional properties of traditional Chinese medicines (TCMs). Ganoderma lucidum and Raphani Semen are famous TCMs that have been shown to help alleviate immune system disorders. However, few studies have experimentally investigated the effects of probiotic-fermented G.lucidum and Raphani Semen on the immune system.

Purpose: We established the in vitro fermentation of G. lucidum and Raphani Semen with a probiotic mixture (Bifidobacterium longum, Lactobacillus acidophilus, and l. fermentum) (GRFB), investigated its ameliorating effect against cyclophosphamide (CTX)-induced immunosuppression, and explored its possible mechanisms.

Methods: First, the different components in GRFB were identified by high-performance liquid chromatography. Second, its immune-stimulatory activities were evaluated in CTX-treated mice. Lastly, its possible in vitro and in vivo mechanisms were studied.

Results: Probiotic fermentation of G. lucidum and Raphani Semen altered some of its chemical constituents, potentially helping improve the ability of GRFB to alleviate immunosuppression. As expected, GRFB effectively ameliorated CTX-induced immunosuppression by increasing the number of splenic lymphocytes and regulating the secretion of serum and ileum cytokines. GRFB supplementation also effectively improved intestinal integrity in CTX-treated mice by upregulating tight junction proteins. It also protects against CTX-induced intestinal dysbiosis by increasing the abundance of beneficial bacteria and reducing the abundance of harmful bacteria. GRFB could directly promote intestinal immunity but not systemic immunity in vitro, suggesting a microbiota-dependent regulation of GRFB. Interestingly, cohousing CTX-induced immunosuppressed mice with GRFB-treated mice promoted their symptoms recovery. Enhanced CTX-induced immunosuppression by GRFB in vitro depended on the gut microbiota. Remarkably, a Kyoto Encyclopedia of Genes and Genomes analysis showed that the GRFB-reprogrammed microbiota was significantly enriched in DNA damage repair pathways, which contribute to repairing the intestinal mucosal barrier.

Conclusion: This is the first study to suggest that compare with unfermented G. lucidum and Raphani Semen, GRFB can more effectively promote intestinal immunity and manipulate the gut microbiota to promote immunostimulatory activity and repair immunosuppression-induced intestinal barrier damage by biotransforming G.lucidum and Raphani Semen components.

Keywords: Ganoderma lucidum; Gut microbiota; Immunity; Immunosuppression; Probiotic fermentation; Raphani Semen.