銀耳免疫調節蛋白 TFP 活化小鼠骨髓衍生性樹突細胞及作為腫瘤疫苗佐劑之探討

Abstract

Tremella fuciformis is one of the fungus that used in traditional medicine in Asian and possesses a variety of pharmacological effects. Tremella fuciformis protein (TFP), an immunomudulatory protein purified from T. fuciformis, has been revealed that can induce cell cytokine production, phagocytic activity and surface marker expression in macrophages via the Toll-like receptor 4 (TLR4). In this study, the immune-activating ability of TFP on lynphocytes and promoting the efficacy of immunotherapeutic vaccines were investigated. We first found that TFP stimulated cell proliferation and IFN-γ production in splenocytes but not in CD90+ T cells. This indicating that antigen-presenting cells (APCs) such as dendritic cells (DCs) could involve in T cell activation. We then examined the TFP-induced activation on murine bone marrow derived DCs and demonstrated that TFP up-regulate the expression of CD40, CD80 and MHC class II and the production of proinflammatory cytokines such us IL-6, TNF-α, IL-1β and IL-10. On the other hand, cytokine production induced by TFP was reduced in TLR4-/- DCs, indicating TFP is recognized mainly by TLR4 to stimulate DCs maturation. Furthermore, TFP-treated DCs activated DO11.10 CD4+ T cells to secrete IFN-γ and further induced T cell proliferation in mixed lymphocyte reaction (MLR), revealing TFP-treated DCs provoke Th1 immune response in vitro. Immunization of mice with TFP-stimulated and ovalbumin (OVA)-pulsed DCs induced an effective regression of tumor growth and long-term survival in a murine E.G7 thymoma model. Injecting TFP-treated OVA-pulsed DCs in tumor-bearing mice reduced serum Il-6 levels. In addition, the number of CD8+CD44hi T cells in splenocytes had increased and the antigen-specific response in vitro had enhanced. These findings provide evidences that TFP induces Th1 response through DC maturation, and highlight TFP as an effective adjuvant for enhancing the efficacy of DC-based antitumor immunotherapy.