Reishi mushroom Ganoderma lucidum Modulates IgA production and alpha-defensin expression in the rat small intestine.

Ethnopharmacological Relevance: Immunoglobulin A (IgA) secretion and alpha-defensins play a role in the innate immune system to protect against infection. Ganoderma lucidum (W.Curt.: Fr.) P. Karst. (Reishi) is a well-known mushroom in traditional Chinese medicine. This study aimed to determine the effects of Reishi on IgA secretion from Peyer's patch (PP) cells and alpha-defensin-5 (RD-5) and RD-6 expression in the rat small intestine.

Materials And Methods: The rats received an oral injection of 0.5-5mg/kg of Reishi powder (1mL/kg) by sonde. All animals were euthanized 24h after Reishi administration. We examined RD-5, RD-6, and Toll-like receptor (TLR) 4 mRNA levels in the jejunum, ileum, and in Peyer's patches (PP) through quantitative real-time PCR analysis. IgA secretion from PP was measured through enzyme-linked immunosorbent assay of the supernatant after primary culture.

Results: Reishi increased IgA secretion in the presence of lipopolysaccharide (LPS) and increased TLR4 mRNA levels, but had no effect on the viability of PP cells. Moreover, Reishi increased RD-5, RD-6, and TLR4 mRNA levels significantly in the ileum in a concentration-dependent manner.

Conclusions: Reishi can induce IgA secretion and increase the mRNA levels of RD-5 and RD-6 in the rat small intestine, through a TLR4-dependent pathway. The present results indicate that Reishi might reduce the risk of intestinal infection.