Mechanisms of Innate Immune Evasion by Mycobacterium Tuberculosis

结核分枝杆菌先天免疫逃避的机制

• 批准号: 10531921
• 负责人: JENNIFER A PHILIPS
• 金额: $ 65.65万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10531921
• 关键词: 2019-nCoV; Alleles; Attenuated; Autophagocytosis; Autophagolysosome; Bacillus; Bacteria; Bacterial Infections; Cause of Death; Cells; Collaborations; Data; Dose; Generations; Goals; Growth; Human; Immune; Immune Evasion; Immunity; Impairment; Infection; Infection Control; Innate Immune Response; Innovative Therapy; Knockout Mice; Lipids; Lung; Lysosomes; Macrophage; Mediator; Microbe; Mitochondria; Modeling; Mus; Mycobacterium tuberculosis; Myeloid Cells; NADP; NADPH Oxidase; Oxidases; Pathway interactions; Persons; Phagocytosis; Phagolysosome; Phagosomes; Phospholipase D; Play; Production; Property; Protein Export Pathway; Protein Secretion; Proteins; Reactive Inhibition; Reactive Oxygen Species; Role; Site; System; Testing; Tetracyclines; Tuberculosis; Tuberculosis Vaccines; Vaccines; Virulence; Virulence Factors; Work; acute infection; antimicrobial; blocking factor; cell type; chronic infection; conditional knockout; improved; in vivo; innate immune function; innate immune mechanisms; innovation; insight; mutant; mycobacterial; neutrophil; novel strategies; pathogen; prevent; recruit; trafficking; tuberculosis treatment

SUMMARY The goal of this project is to understand how two virulence factors from Mycobacterium tuberculosis (Mtb), CpsA and phthiocerol dimycocerosate (PDIM), impair immunity by undermining both classical and non-classical autophagy. Mtb is the causative agent of tuberculosis (TB), the leading cause of death worldwide from a bacterial infection. The main cellular niche for Mtb is macrophages and neutrophils, the very immune cells that are meant to clear infection. How Mtb survives the innate immune response to establish infection is not well understood. In the previous project period, we discovered that an exported protein, CpsA, is critically important for Mtb virulence. We showed that CpsA inhibits phagosomal recruitment of the NADPH oxidase. The NADPH oxidase makes reactive oxygen species (ROS), an important mediator of the innate immune response. In addition to its direct antimicrobial activity, ROS is required for a lysosomal trafficking pathway called LC3-associated phagocytosis (LAP), a non-classical form of autophagy. Thus, by inhibiting ROS, CpsA also inhibits LAP. We showed both in macrophages and mice that CpsA protects Mtb from the NADPH oxidase and LAP. Interestingly, CpsA physically interacts NDP52 and TAX1BP1, autophagy adaptors that function in a form of classical autophagy (xenophagy), suggesting that CpsA may also impair xenophagy. Moreover, we found that the Mtb virulence lipid, PDIM, also inhibits the NADPH oxidase. Previous studies proposed an array of roles for PDIM and showed that it protects Mtb from a poorly defined innate killing mechanism. Our data suggest that an unappreciated virulence property of PDIM is blocking the NADPH oxidase and LAP. Thus, we hypothesize that CpsA inhibits xenophagy and works in concert with PDIM to inhibit the NADPH oxidase and LAP. Further, we propose that the infectious dose of Mtb depends upon its ability to evade these innate defenses in myeloid cells that are recruited to the lungs during initial infection. Here, we will define how CpsA inhibits the NADPH oxidase and investigate whether it also impairs xenophagy by blocking NDP52 and TAX1BP1 function. We will determine whether PDIM also impairs recruitment of the NADPH oxidase to mycobacterial phagosomes and evaluate the contribution that PDIM plays towards subverting the NADPH oxidase and LAP in vivo. To determine whether CpsA promotes the establishment of infection, we will use an ultra-low dose infection model in mice. Using conditional knockout (cKO) mice, we will determine in which cells CpsA functions to inhibit the NADPH oxidase and LAP during acute and chronic infection. Our findings will provide mechanistic insight into how two key virulence factors in Mtb collaborate to undermine immunity. Our studies will reveal a cell type-specific virulence strategy of the bacilli, delineate the cell types that participate in LAP in vivo, and define host-pathogen interactions that govern the establishment of infection. Our studies will provide detailed mechanistic insight into the immune evasion strategies of one of the world's most formidable pathogens. By elucidating the mechanism of action of two crucial virulence factors in Mtb, we will advance innovative approaches to prevent and treat TB.

概括 该项目的目的是了解结核分枝杆菌（MTB）的两个毒力因素如何 和邻苯二甲生物盐（PDIM），通过破坏经典和非经典性而损害免疫力 自噬。 MTB是结核病（TB）的病因，TB是全世界死亡的主要原因 感染。 MTB的主要细胞生态位是巨噬细胞和嗜中性粒细胞，这是非常免疫细胞 清除感染。 MTB如何生存天生的免疫反应以建立感染尚不清楚。在 上一个项目时期，我们发现出口的蛋白质CPSA对于MTB毒力至关重要。 我们表明，CPSA抑制了NADPH氧化酶的吞噬体募集。 NADPH氧化酶使 活性氧（ROS），是先天免疫反应的重要介体。除了直接 抗菌活性，ROS是溶酶体运输途径，称为LC3相关的吞噬作用 （LAP），一种非经典形式的自噬形式。因此，通过抑制ROS，CPSA也抑制膝盖。我们在 CPSA可保护MTB免受NADPH氧化酶和膝盖的巨噬细胞和小鼠。有趣的是，CPSA身体上 相互作用NDP52和税务1BP1，即以经典自噬（Xenophagy）形式起作用的自噬适配器， 表明CPSA也可能会损害Xenophapy。此外，我们发现MTB毒力脂质PDIM，也 抑制NADPH氧化酶。先前的研究提出了PDIM的一系列角色，并表明它可以保护 MTB来自定义不明的先天杀人机制。我们的数据表明，不欣赏的毒力性能 PDIM的of堵塞了NADPH氧化酶和膝盖。因此，我们假设CPSA抑制了异种和 与PDIM协同工作以抑制NADPH氧化酶和膝盖。此外，我们建议传染剂量 MTB的of取决于其逃避这些先天防御的能力 在初始感染期间。在这里，我们将定义CPSA如何抑制NADPH氧化酶，并研究它是否也 通过阻止NDP52和税务1BP1功能来损害Xenophapy。我们将确定PDIM是否也损害 将NADPH氧化酶募集到分枝杆菌吞噬体并评估PDIM发挥的贡献 朝着体内颠覆NADPH氧化酶和膝盖。确定CPSA是否促进 建立感染，我们将在小鼠中使用超低剂量感染模型。使用有条件的淘汰赛 （CKO）小鼠，我们将确定哪些细胞CPSA在急性期间抑制NADPH氧化酶和膝盖的功能 和慢性感染。我们的发现将提供有关MTB中两个关键毒力如何的机械洞察力 协作以破坏免疫力。我们的研究将揭示细胞类型特异性的毒力策略， 描述参与体内膝上的细胞类型，并定义控制宿主 - 病原体相互作用 建立感染。我们的研究将为免疫逃避提供详细的机械洞察力 世界上最强大的病原体之一的策略。通过阐明两个至关重要的作用机理 MTB中的毒力因素，我们将提出预防和治疗结核病的创新方法。