Immune-Enhancing Effect of Submerged Culture of Ceriporia lacerata Mycelia on Cyclophosphamide-Induced Immunosuppressed Mice and the Underlying Mechanisms in Macrophages

The white-rot fungi Ceriporia lacerata is used in bioremediation, such as lignocellulose degradation, in nature. Submerged cultures and extracts of C. lacerata mycelia (CLM) have been reported to contain various active ingredients, including beta-glucan and extracellular polysaccharides, and to exert anti-diabetogenic properties in mice and cell lines. However, the immunostimulatory effects have not yet been reported. This study aimed to identify the immunomodulatory effects, and underlying mechanisms thereof, of submerged cultures of CLM using RAW264.7 macrophages and cyclophosphamide (CTX)-induced immunosuppression in mice. Compared to CTX-induced immunosuppressed mice, the spleen and thymus indexes in mice orally administered CLM were significantly increased; body weight loss was alleviated; and natural killer (NK) cytotoxicity, lymphocyte proliferation, and cytokine (tumor necrosis factor [TNF]-alpha, interferon [IFN]-gamma, and interleukin [IL]-2) production were elevated in the serum. In RAW264.7 macrophages, treatment with CLM induced phagocytic activity, increased the production of nitric oxide (NO), and promoted mRNA expression of the immunomodulatory cytokines TNF-alpha, IFN-gamma, IL-1 beta, IL-6, IL-10, and IL-12. In addition, CLM increased the inducible NO synthase (iNOS) concentration in macrophages, similar to lipopolysaccharide (LPS) stimulation. Mechanistic studies showed that CLM induced the activation of the NF-kappa B, PI3k/Akt, ERK1/2, and JNK1/2 pathways. Moreover, the phosphorylation of NF-kappa B and I kappa B induced by CLM in RAW264.7 cells was suppressed by specific MAPKs and PI3K inhibitors. Further experiments with a TLR4 inhibitor demonstrated that the production of TNF-alpha, IL-1 beta, and IL-6 induced by CLM was decreased after TLR4 was blocked. Overall, CLM protected against CTX-induced adverse reactions by enhancing humoral and cellular immune functions, and has potential as an immunomodulatory agent.

Automated summary

Compared to CTX-induced immunosuppressed mice, mice orally administered CLM showed significantly increased spleen and thymus indexes, alleviated body weight loss, and elevated levels of natural killer (NK) cytotoxicity, lymphocyte proliferation, and cytokine production in the serum. Treatment with CLM also induced phagocytic activity, nitric oxide (NO) production, and mRNA expression of immunomodulatory cytokines in RAW264.7 macrophages, indicating its potential as an immunomodulatory agent.