The role of mitochondrial reactive oxygen species in innate immune signaling

7.项目概要/摘要： 人体防御传染病的一个重要组成部分是先天免疫系统。巨噬细胞和其他组成该系统的白色血细胞是感染的第一反应者，识别入侵的病原体并启动免疫反应。这种反应的中心特征是宿主炎症介质和I型干扰素（IFN）的上调和分泌。连接病原体识别与I型IFN产生的分子基础尚不清楚，但依赖于内质网和内质网定位的衔接蛋白，干扰素基因刺激因子（STING）。该研究的目的是表征STING依赖性信号传导通路的激活，以进一步实现描绘I型IFN在巨噬细胞胞内感染期间如何调节的长期目标。某些细胞内病原体调节宿主线粒体的功能。假设巨噬细胞的细胞内感染引起线粒体失调，促进活性氧（ROS）的产生，激活STING依赖性先天免疫途径，导致原型I型IFN、IFN-β的表达。小分子5，6-二甲基咕吨酮-4-乙酸（DMXAA）是巨噬细胞中STING依赖性信号传导的有效激活剂，并将用作细胞内感染的替代物。此外，将检查巨噬细胞中STING依赖性激活对细胞内细菌（土拉弗朗西斯菌）或病毒（呼吸道合胞病毒（RSV））感染的反应。本研究的第一个目的是确定线粒体ROS产生是否足以用于STING二聚化和下游信号传导组分的活化，并确定在感染或化学处理期间线粒体ROS产生对于IFN-β表达的必要性。第二个目标将确定线粒体功能和线粒体ROS如何通过感染或DMXAA治疗来调节。预计在DMXAA处理或感染F.在STING的ROS依赖性二聚化之后，Tularensis或RSV是激活STING依赖性先天免疫信号传导途径所必需的。由于感染性疾病中线粒体颠覆的潜在共性，该项目中表征的机制可能对其他感染性生物具有广泛的应用。

7. Project Summary/ Abstract: An essential component of the body¿s defense against infectious disease is the innate immune system. Macrophages and other white blood cells that comprise this system are the first responders to infection and recognize invading pathogens and initiate an immune response. A central feature of this response is the upregulation and secretion of host inflammatory mediators and Type I Interferons (IFNs). The molecular basis connecting pathogen recognition to Type I IFN production is unclear, but is dependent upon the mitochondrialand endoplasmic reticulum-localized adapter protein, Stimulator of Interferon Genes (STING). The objective of the study is to characterize the activation of STING-dependent signaling pathway(s) to further the long-term goal of delineating how Type I IFNs are regulated during intracellular infection of macrophages. Certain intracellular pathogens modulate the function of host mitochondria. It is hypothesized that intracellular infection of macrophages causes mitochondrial dysregulation, prompting generation of Reactive Oxygen Species (ROS), activating STING-dependent innate immune pathways, leading to expression of the prototypical type I IFN, IFN-Beta. The small molecule 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is a potent activator of STING-dependent signaling in macrophages and will be used as a surrogate for intracellular infection. Additionally, STING-dependent activation in macrophages will be examined in response to an intracellular bacterial (Francisella tularensis) or viral (Respiratory Syncytial Virus (RSV)) infection. The first Aim of the study will be to determine whether mitochondrial ROS generation is sufficient for STING dimerization and activation of downstream signaling components, and establish the necessity of mitochondrial ROS generation for IFN-Beta expression during infection or chemical treatment. The second Aim will establish how mitochondrial function and mitochondrial ROS is modulated by infection or DMXAA treatment. It is predicted that mitochondrial ROS generated during DMXAA treatment, or infection with F. tularensis or RSV, will be necessary for activation of STING-dependent innate immune signaling pathways following ROS-dependent dimerization of STING. Due to the potential commonality of mitochondrial subversion in infectious disease, the mechanism characterized in this project could have wide-ranging applications to other infectious organisms.