树突状细胞在减毒李斯特菌肝癌疫苗Lmdd-MPFG抗肿瘤作用中的免疫调控机制研究

减毒李斯特菌LM疫苗能激发机体产生有效的抗肿瘤免疫，目前已应用于多种肿瘤的临床I期试验。我们已制备了dal和dat基因缺失的高度减毒李斯特菌肝癌疫苗Lmdd-MPFG，其靶基因MPFG是以HBcAg、HBxAg、AFP、MAGE-3为靶点构建的病毒类似颗粒（VLP）多价CTL表位基因。前期研究已证实该疫苗在诱导肿瘤特异性CTL时，亦能打破肿瘤微环境的免疫抑制状态，但是确切机制尚不清楚。本研究拟在前期工作基础上，在细胞水平和动物模型上明确肝癌减毒Lmdd-MPFG疫苗与促DC分化成熟的关系，再通过抗体封闭、基因敲除或siRNA干扰等技术对Lmdd-MPFG对DC的影响进行深层次的机制分析研究，确定调控DC活化的关键NLR分子和多维动态调控网络，进而研究DC内NLR的功能状态对T细胞亚群等炎症细胞的影响，以探讨DC在Lmdd-MPFG疫苗抗肿瘤作用中的调控机制，为开展肝癌临床免疫治疗提供依据。

Attenuated Listeria Monocytogenes (LM) vaccine has been investigated in many phase I clinical trials against various tumors for its high efficacy to elicit anti-tumor immunity in the body. In our previous study, we have developed a LM vaccine against hepatocellular carcinoma, Lmdd-MPFG, which is a highly attenuated LM vaccine with dal and dat regions deletion. The antigen MPFG will form a multi-CTL-epitopes virus like particle including HBcAg、HBx Ag、AFP、MAGE-3 epitopes. Our previous results showed Lmdd-MPFG can not only induce hepatocellular cancer specific CTLs, but also break the negative immune regulation in tumor microenvironment. However, the mechanism how the vaccine works still remains unclear. In this study, we will further elucidate, based on our previous study, the relationship between Lmdd-MPFG and dendritic cell differentiation and maturation in vitro and in vivo. The potential relationship will be proved by antibody blocking, key genes knockout models and siRNA interference. The roles of NOD like receptors will be focused in the network of Lmdd-MPFG and DC. The effects of DC on the T cell subtypes and functionality will be addressed as well. The whole study will unravel the complexity regulatory role of DC in the Lmdd-MPFG induced anti-tumor immunity and provide principles for clinical trials to treat liver cancers.