p38信号通路调节对DC疫苗免疫治疗骨髓瘤的作用和机理研究

Although high-dose chemotherapy plus autologous stem cell transplantation (ASCT) can achieve complete remission (CR) in nearly 50% of newly diagnosed MM patients, most patients eventually relapse and die from their disease. Clearly, the minimal residual diseases (MRDs) are resistant to current therapies, leading to relapse, highlighting the importance of developing approaches to target MRDs. Immunotherapy presents an appropriate alternative option. Dendritic cells (DCs) are the key antigen presenting cells and play an important role in establishing anti-tumor immunity. However, preliminary reports of DC-based immunotherapy in human MM have demonstrated minor clinical responses. The underlying mechanisms are not fully defined. We previously found that MM cells or tumor culture conditioning medium (TCCM) inhibit the differentiation and function of bone marrow-derived DCs (BMDCs) through activating p38 MAP kinase (p38) signaling pathway, and inhibiting p38 (by inhibitor SB203580, SB) during differentiation restored the phenotype and function of TCCM-treated BMDCs (TCCM-DC). We also found that monocyte-derived DCs (MoDCs) from MM patients are phenotypically and functionally defective and the abnormalities of patient-derived MoDCs are attributed, at least partially, to the constitutively activated p38 in the DC progenitors, because the addition of SB during moDC differentiation could correct these abnormalities. Recent investigations showed that p38 signaling plays a central role in the priming of Th17 cells and autoimmune inflammation. Since tumor immunity is closely related to autoimmunity, p38 may also play an important role for the generation of effective antitumor immunity. Based on these observations, we hypothesize that in vitro generation of tumor derived DCs by modulation of p38 signaling pathway (i.e. inhibiting p38 during differentiation and activating p38 during maturation) will program DCs to drive antitumor immunity. Interestingly, our preliminary data showed that BMDCs matured by a p38 activator (curdlan) exhibited higher levels of co-stimulatory surface molecules and IL-12 expression than cells matured by the regular maturation reagents: TNF-alpha and IL-1beta. This application is aimed to explore the cellular and molecular mechanisms underlying these novel findings and their clinical significance. We will further examine the phenotype and function of tumor-derived DCs generated by p38 modulation. We will examine the therapeutic efficacy, the helper T (Th) cell subsets and the cytotoxic T lymphocytes (CTLs) induced by DCs generated by p38 modulation. We will further clarify molecular mechanisms involved in the improvement of antitumor immunity by p38 modulation. Successful completion of these studies will not only provide a better understanding of the mechanisms underlying p38 modulation in the improvement of anti-tumor immunity, but also may have a major impact on the design of therapeutic DC vaccines for MM.

多发性骨髓瘤（MM）是不治之症，主要原因是化疗后微小残留病(MRD)。免疫治疗可清除MRD。树突状细胞（DC）在建立抗肿瘤免疫中起重要作用。但DC疫苗对MM临床疗效有限。申请者前期研究发现MM病人单核细胞分化而来的DC（moDC，常用于DC疫苗）有表型和功能的缺陷；在DC分化阶段，加入p38丝裂原活化蛋白激酶（p38）抑制剂可纠正这些缺陷，产生功能相当于健康人来源的moDC。但近期研究显示p38是DC诱导Th17细胞亚群和自身免疫所必需。由于肿瘤免疫与自身免疫密切相关，因此，p38可能也是DC诱导肿瘤免疫所必需。据此我们推测体外生产肿瘤来源DC的策略是：在分化阶段抑制p38，在成熟阶段激活p38。本课题的目的是研究p38调节（抑制/激活）对肿瘤来源DC的表型、功能和DC疫苗体内外诱导抗肿瘤免疫的作用，并阐明抗肿瘤免疫的细胞和分子机制，为设计有效的MM治疗性DC疫苗提供新思路。

多发性骨髓瘤（MM）是不治之症。免疫治疗是一种很有前途的肿瘤治疗方法，包括对MM的治疗。树突状细胞（DCs）在建立抗肿瘤免疫中起重要作用。但我们在以往的研究中发现MM患者单核细胞分化而来的DC（moDC，常用于DC疫苗）存在表型和功能的缺陷。因此如何优化DC的体外分化是提高DC疫苗的抗肿瘤效应的关键一环。在本项目研究中，我们通过在DC成熟阶段加入Dectin-1信号活化剂Curdlan激活P38信号，从而优化DC表型和功能，增强其体内体外的抗肿瘤效应，我们也更深入地探讨了其内在机制。Th9是重要的抗肿瘤效应细胞。我们发现Dectin-1信活化的DCs（dectin-1-DCs）体内体外促进Th9的生成，并体内诱导产生比常规DC疫苗更强的抗肿瘤效应，而且dectin-1-DCs诱导抗肿瘤效应依赖于其诱导产生的Th9和IL-9。进一步分析发现Dectin-1-DCs高表达TNF-α、TNFSF15、OX40L和IL-33。我们后续研究发现这些因子在Dectin-1-DCs诱导Th9和体内的抗肿瘤效应中起重要作用。我们的研究发现Dectin-1-DCs诱导的Th9高表达IL-24和颗粒霉素B（GzmB）。IL-24是一种肿瘤抑制基因，我们在下一步的研究中将进一步深入探讨Dectin-1信号促进DCs表达IL-24的分子机制，以及IL-24在Dectin-1-DCs诱导的Th9发挥抗肿瘤效应中的作用。我们的研究为dectin-1-DCs为基础的DC疫苗应用于临床肿瘤治疗提供了理论依据，为体外诱导生成更有效的DC肿瘤疫苗提供了新靶点。