The role of mitochondrial reactive oxygen species in innate immune signaling

描述(由申请人提供)：人体抵御传染病的一个重要组成部分是先天免疫系统。组成这一系统的巨噬细胞和其他白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。这种反应的一个中心特征是宿主炎症介质和I型干扰素(IFN)的上调和分泌。病原体识别与I型干扰素产生之间的分子基础尚不清楚，但依赖于线粒体和内质网定位的适配蛋白干扰素基因的刺激物(STING)。本研究的目的是研究STING依赖的信号通路(S)的激活特征，以进一步阐明I型IFN在巨噬细胞内感染过程中的调控机制。某些细胞内病原体调节宿主线粒体的功能。据推测，巨噬细胞的细胞内感染导致线粒体失调，促使活性氧物种(ROS)的产生，激活依赖刺痛的天然免疫途径，导致I型干扰素(I型干扰素)的表达。小分子5，6-二甲基黄原酮-4-醋酸(DMXAA)是巨噬细胞刺痛依赖信号的有效激活剂，有望作为细胞内感染的替代物。此外，巨噬细胞中依赖刺的激活将在细胞内细菌(图拉氏方济氏菌)或病毒(呼吸道合胞病毒(RSV))感染时进行检测。这项研究的第一个目的将是确定线粒体ROS的产生是否足以刺激下游信号成分的二聚化和激活，并确定在感染或化学处理过程中线粒体ROS产生对干扰素-β表达的必要性。第二个目标将确定感染或DMXAA治疗如何调节线粒体功能和线粒体ROS。据预测，DMXAA处理过程中产生的线粒体ROS，或者感染图拉氏F菌或RSV，将是激活依赖于STIN的天然免疫信号通路所必需的，而SING依赖于ROS的二聚化。由于线粒体颠覆在传染病中的潜在共性，本项目所描述的机制可能在其他感染性生物中具有广泛的应用。

DESCRIPTION (provided by applicant): 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 up- regulation 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 mitochondrial- and 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-¿. 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- ¿ 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.