Pleurotus ferulae water extract enhances the maturation and function of murine bone marrow-derived dendritic cells through TLR4 signaling pathway

Dendritic cells (DCs) play important roles in the regulation of immune system, which link innate and adaptive immune responses. Mature DCs produced interleukin (IL)-12 promote optimal type 1 T helper (Th1) cells and cytotoxic T lymphocytes. The extracts of traditional herbal medicines have been shown to enhance immune responses through promoting the maturation and cytokine production of DCs. Here, we investigated the effects of Pleurotus ferulae water extract (PFWE) on the maturation and function of bone marrow-derived DCs (BM-DCs). Upon PFWE treatment, BM-DCs dose-dependently upregulated the expression of CD40, CD80, CD86 and MHC II and increased the production of IL-12, IL-6 and tumor necrosis factor (TNF)-α but not for IL-10, which is mediated by TLR4 signaling pathway, at least partially. The production of prostaglandin E2 (PGE2) in BM-DCs was decreased by the treatment of PFWE. Moreover, PFWE treatment decreased the expression of active Caspase-3 but increased the expression of CCR7. PFWE treated DCs enhanced the proliferation of allogenic CD8(+) T cells and the capacity of antigen presenting to autologous CD8(+) T cells. The combination of PFWE and CpG-ODN further enhanced the maturation and function of murine BM-DCs. The results showed that PFWE could enhance the maturation and function of DCs through TLR4 signaling pathway and has additive effect when combined with CpG-ODN, suggesting that PFWE alone or combined with CpG-ODN could be used to enhance the immune responses.