miRNA调控T细胞耗竭的作用机制及其抗肿瘤生物治疗的研究

T cell exhaustion is an emerging defined immune suppression mechanism in which T cells reactive to tumor antigens lose their ability to kill cancer cells. It promotes tumor progression and attenuates therapeutic effects of adoptive transfer immunotherapy. Upregulated expression of immune inhibitory receptors (iRs) such as PD1, TIM3 and BTLA play a vital role to immune suppression in cancer: blockade of these iRs reverses tumor-induced T cell exhaustion in vitro, reduces tumour growth in vivo, and confers a survival advantage in various cancers including melanoma. However, it is not known how iRs are concurrently regulated in the scenario of melanoma progress and in immunotherapy. Our preliminary data suggest that miRNAs may be causally associated with T cell exhaustion. However, there has been little research on the regulatory role of miRNAs in T cell exhaustion, nor exploration of the therapeutic potential of miRNAs in melanoma immunotherapy. Little is known of the effects of miRNAs on PD1, TIM3, and BTLA in melanoma and T cell exhaustion. We will address the following questions about miRNA-mediated immunomodulation in cancer: 1) Do these miRNAs regulate PD1, TIM3, and BTLA and, if so, 2) Can miRNAs reverse T cell exhaustion and immune suppression in melanoma? 3) Can introduction of miRNA into T cells ex vivo or in vivo enhance immunotherapeutic transfer to treatment of melanoma? The Objective of this study is to explore the roles of miRNA in T cell exhaustion and identify miRNA targets for therapy in melanoma. .The proposed work will provide deeper insight into the role of miRNA in T cell exhaustion and immune suppression through modulation of negative regulators of T cell function, address fundamental biological questions pertaining to miRNA dysregulation in T cell exhaustion, and explore the potential of miRNAs as anticancer agents to increase immune cell recognition and ablation of tumors.

肿瘤来源的负性免疫调节机制尚未完全明了。新近研究表明，由T细胞耗竭（T cell exhaustion）引起的免疫功能减弱可引起肿瘤的免疫耐受以及导致肿瘤免疫治疗无效，但调控机制有待阐明。我们的前期研究结果提示：miRNA (miR28/107/150)表达失调促进了抑制性受体PD1、TIM3、BTLA的上调，从而导致T细胞耗竭。但是目前与 T 细胞耗竭相关的 miRNAs 还未曾报道，诸多重要问题还悬而未决。本项目拟探讨以下三个方面的内容：①探索miR28/107/150在黑色素瘤中调节耗竭性T细胞的作用机制；②评估通过上调miRNAs能否恢复抗肿瘤免疫力并提高黑色素瘤免疫治疗效果；③研究miRNAs在肿瘤环境中如何被调控的，以及相关的表观遗传学调控机制。本研究将深入探讨T细胞耗竭的特点及其相关免疫机制，为肿瘤的免疫治疗提供新思路，不但有重要的理论意义，而且还有较强的应用价值和临床意义。

基于树突细胞（DC）的免疫疗法是临床癌症治疗的一种有前途的方法。 miRNA是一类小的非编码RNA分子，可与RNA结合以介导在多种生物学中重要的过程。 miRNA调节剂可能是增强基于DC的抗癌免疫疗法的有效药物。使用miRNA芯片分析鉴定 出具有代表性的miR-5119，可能调节DC中免疫抑制受体（IR）。我们评估了具有免疫能力的肿瘤小鼠的DC中IR和miR-5119的配体水平，并检查了miR-5119的分子靶标。结果显示miRNA-5119在小鼠DC中被下调。在生物信息学分析和qPCR数据中显示，miRNA-5119靶向编码多个负性免疫调节分子的mRNA，包括IR的配体，例如PD-L1和IDO2。表达miR-5119的DC可以下调PD-L1,并防止肿瘤小鼠的T细胞衰竭。此外，miR-5119工程改造的DC在体外和体内均可有效恢复衰竭性CD8 + T细胞的功能，从而产生强大的抗肿瘤细胞免疫应答，上调细胞因子分泌，减少T细胞凋亡和衰竭。用miR-5119工程改造的DC疫苗治疗肿瘤小鼠可减少T细胞衰竭并抑制小鼠肿瘤的生长。这项研究为使用miRNA-5119设计的DC疫苗来调节肿瘤小鼠模型中的免疫抑制性受体并增强抗肿瘤免疫应答的新型治疗方提供了支持。因此，基于miRNA / DC的免疫疗法作为基于DC的抗癌免疫疗法的新策略，具有潜在的临床应用潜力。