运动应激下TOM70/Tfam介导线粒体调控先天性免疫反应的研究

Mitochondria were originally considered as the fuel center of cells, and were shown to be involved in apoptosis. However, recent evidence suggests that mitochondria also take part in innate immune response to a great extent. Besides, Tfam and TOMs, which have been demonstrated to be involved in exercise-mediated mitochondrial quality control, were also found to be related to certain signaling pathways of innate immune response. Therefore, it was hypothesized that one of the pathways that mediate exercise-induced innate immune response could be regulated by alterations of the structure, function and relating signaling molecules of mitochondria. In the present study, we will establish cell models, altering mitochondrial ROS level and knocking out the genes of TOM70 and Tfam, respectively. In addition, we will construct animal models, overexpressing TOM70 and Tfam, respectively and intervening with exercise training. We aim to investigate the role of DNA stability in cGAS-STING signaling pathway, reveal the association between PIM and MAVS, as well as the discuss the effect of above experimental manipulation on NF-κB and IRF signaling cascade. We hope that the effect of exercise on mitochondria-mediated innate immune response, and new mechanism of exercise regulating immune system could be explored by completion of this study.

线粒体最初被认为是细胞的动力中心，并参与调节凋亡通路。然而，近期的研究表明，线粒体还在很大程度上参与先天性免疫反应。另外，Tfam和TOMs等已被证实参与运动介导线粒体质量控制的因子也被发现与先天性免疫反应的信号通路存在某种关联。因此，运动干预先天性免疫反应的若干途径之一可能是通过调控线粒体的结构、功能及相关信号分子得以实现的。在本研究中，我们拟通过建立细胞模型，对线粒体ROS水平进行干预，并分别敲除TOM70和Tfam两个关键分子；通过建立动物模型，对TOM70和Tfam分别进行过表达处理，并辅以运动训练干预，探讨线粒体DNA稳定性对cGAS-STING信号通路的调控机制，揭示线粒体输入机制（PIM）与MAVS间的联系，及其对下游NF-κB和IRF信号级联反应的影响，多部位、多水平探讨运动对线粒体介导先天性免疫反应的干预作用，揭示运动调控免疫系统的新机制。

诸多证据显示，不同强度、不同时间的运动对先天性免疫发挥不同的调控作用，然而其机制并不完全明了。近年来的研究表明，线粒体积极参与先天性免疫反应。基于此，本课题提出假设：运动可能通过调控线粒体结构、功能及相关分子通路调控先天性免疫。本课题通过建立乌拉坦诱导的肺癌模型、DEN诱导的肝癌模型，并施加不同方式、不同强度和持续时间的运动干预，探讨运动对先天性免疫的作用及机制。结果显示：中等强度的急性运动通过减少肝脏胞浆和血浆mtDNA的含量，并通过调控白细胞TLR9和cGAS/STING信号分子的表达发挥抗炎作用，而急性力竭运动则发挥相反作用。此外，急性离心损伤运动造成的血清游离mtDNA含量的增加不是引起骨骼肌损伤炎症反应的原因，因为急性离心损伤运动抑制了骨骼肌内线粒体相关免疫蛋白的转录，并且cGAS-STING-TBK1-IRF3-IFN-β信号通路未被激活。基于DEN诱导肝肿瘤的研究显示，中等强度运动通过抑制炎症因子IL-1和IL-6抑制DEN诱导引起的肝脏炎症反应，且通过树突状细胞、巨噬细胞和NLRP3炎症小体激活先天性免疫，通过CD8重启免疫监视阻止肿瘤细胞逃逸，而高强度间歇运动没有此作用。上述研究为线粒体介导的运动对先天性免疫的调控作用及机制提供了新证据。