基于“癌源mtDNA传递”探讨STING通路在结肠癌中诱导形成肠黏膜免疫麻痹微环境的效应与机制

Mucosal microenvironment is critical for host immune defenses against colon cancer cells, which can cause mitochondria damage in early cancer cells that further release various DAMPs (such as mtDNA). STING distributed within lamina propria is newly recognized as the specific sensor of mtDNA. Tunneling nanotubes between eukaryocytes provide a tunnel for mtDNA transfer. We hypothesize that tumor mtDNA activates STING signaling that leads to apoptotic events in mucosal dendritic cells (DCs). This effect can be diffused into surrounding DCs through mtDNA transfer. We will establish MitoCeption system to observe and quantify the tumor mtDNA horizontal transfer between mucosal DCs, and investigate the effect of such process in promoting extensive apoptosis of mucosal DCs. We will further evaluate the DC-dependent differentiation of CD4+ and CD8+ T cells and the secretion of associated anti-tumor molecules. This study will clarify the pivotal role of STING-mediated tumor mtDNA in the mucosal immunoparalysis microenvironment, and thereby promoting the development of clinical diagnostic and therapeutic strategies against mtDNA in colon cancer.

肠黏膜免疫微环境是机体抵御结肠癌细胞增殖转移的关键。早期癌细胞在免疫系统攻击下出现线粒体损伤，释放出以线粒体DNA (mtDNA) 为代表的免疫学介质。肠黏膜内存在以STING为主的mtDNA特异性识别通路，真核细胞间存在可供mtDNA传递的纳米通道。本研究提出癌源mtDNA可经STING介导肠黏膜DC凋亡，此效应可经DC间“癌源mtDNA传递”级联放大，介导肠黏膜DC由“局灶性凋亡”进展为“广泛性凋亡”。为此，本研究拟构建MitoCeption体系，明确STING介导DC凋亡的分子学机制，量化肠黏膜DC间“癌源mtDNA传递”的水平，探讨此过程抑制DC依赖性CD4+与CD8+T细胞分化与抗肿瘤因子生成的效应。此研究将阐述STING介导的癌源mtDNA诱导形成肠黏膜免疫麻痹微环境的机制，明确mtDNA在肿瘤微环境中的核心角色，指导临床针对mtDNA探索新的肿瘤诊断与治疗手段。

肠黏膜免疫微环境是机体抵御结肠癌细胞增殖转移的关键，早期癌细胞在免疫系统攻击下出现线粒体损伤，释放出以线粒体DNA（mtDNA）为代表的免疫学介质，肠黏膜内存在以STING为主的mtDNA特异性识别通路，真核细胞间存在可供mtDNA传递的纳米通道。本研究提出癌源mtDNA可经STING介导肠黏膜DC凋亡，此效应可经DC间“癌源mtDNA传递”级联放大，介导肠黏膜DC由“局灶性凋亡”进展为“广泛性凋亡”。为此，本研究开发了STING-/-及其上游基因cGAS-/-基因敲除小鼠模型，构建了AOM/DSS小鼠结肠肿瘤模型，优化健全了肠黏膜原代DC及T细胞分离纯化流程，建立了MitoCeption体系，利用激光共聚焦、流式细胞分选、免疫组化、细胞共培养等细胞及分子生物学技术，明确了STING介导DC凋亡的分子学机制，量化了肠黏膜DC间“癌源mtDNA传递”的水平，探讨了此过程抑制DC依赖性CD4+与CD8+T细胞分化与抗肿瘤因子生成的效应。本研究阐述了STING介导的癌源mtDNA诱导形成肠黏膜免疫麻痹微环境的效应及机制，明确了mtDNA在肿瘤微环境中的核心角色，有助于指导临床针对mtDNA探索新的肿瘤诊断与治疗手段。