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Mechanisms of Innate Immune Evasion by Mycobacterium Tuberculosis

结核分枝杆菌先天免疫逃避的机制

基本信息

批准号：
10390674
负责人：
JENNIFER A PHILIPS
金额：
$ 66.07万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
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/10390674
关键词：
2019-nCoV Alleles Attenuated Autophagocytosis Autophagolysosome Bacillus Bacteria Bacterial Infections Cause of Death Cells Data Dose Generations Goals Growth Human Immune Immune Evasion Immunity Impairment Infection Infection Control Innate Immune Response Innovative Therapy Knockout Mice Lipids Lung Lysosomes Mediator of activation protein 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 Proteins 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 macrophage mutant mycobacterial neutrophil novel strategies pathogen prevent recruit trafficking tuberculosis treatment

项目摘要

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.

概括该项目的目标是了解结核分枝杆菌 (Mtb) CpsA 的两种毒力因子如何和 phthiocerol dimycocerosate (PDIM)，通过破坏经典和非经典来损害免疫力自噬。 Mtb 是结核病 (TB) 的病原体，而结核病是全球范围内细菌性死亡的主要原因感染。结核分枝杆菌的主要细胞生态位是巨噬细胞和中性粒细胞，这正是免疫细胞以清除感染。结核分枝杆菌如何在先天免疫反应中存活并建立感染尚不清楚。在在上一个项目期间，我们发现一种输出蛋白 CpsA 对于 Mtb 毒力至关重要。我们发现 CpsA 抑制 NADPH 氧化酶的吞噬体募集。 NADPH 氧化酶使活性氧（ROS），先天免疫反应的重要介质。除了它的直接抗菌活性，ROS 是称为 LC3 相关吞噬作用的溶酶体运输途径所必需的（LAP），一种非经典形式的自噬。因此，通过抑制 ROS，CpsA 也抑制 LAP。我们都在在巨噬细胞和小鼠中，CpsA 保护 Mtb 免受 NADPH 氧化酶和 LAP 的侵害。有趣的是，CpsA 在物理上与 NDP52 和 TAX1BP1 相互作用，这些自噬适配器以经典自噬（异体自噬）的形式发挥作用，表明 CpsA 也可能损害异体吞噬。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 的一系列作用，并表明它可以保护 Mtb 来自定义不明确的先天杀伤机制。我们的数据表明，一种未被重视的毒力特性 PDIM 会阻断 NADPH 氧化酶和 LAP。因此，我们假设 CpsA 抑制异体吞噬并且与 PDIM 协同作用，抑制 NADPH 氧化酶和 LAP。此外，我们建议感染剂量结核分枝杆菌的能力取决于其逃避招募到肺部的骨髓细胞的先天防御的能力在最初感染期间。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断 NDP52 和 TAX1BP1 功能来损害异体吞噬。我们将确定 PDIM 是否也会损害将 NADPH 氧化酶招募到分枝杆菌吞噬体并评估 PDIM 的贡献破坏体内 NADPH 氧化酶和 LAP。确定 CpsA 是否促进建立感染后，我们将使用小鼠超低剂量感染模型。使用条件淘汰赛 (cKO) 小鼠，我们将确定在急性期哪些细胞 CpsA 发挥抑制 NADPH 氧化酶和 LAP 的作用和慢性感染。我们的研究结果将为 Mtb 的两个关键毒力因子如何发挥作用提供机制见解。合作破坏免疫力。我们的研究将揭示杆菌的细胞类型特异性毒力策略，描述体内参与 LAP 的细胞类型，并定义控制 LAP 的宿主-病原体相互作用感染的建立。我们的研究将为免疫逃避提供详细的机制见解世界上最可怕的病原体之一的策略。通过阐明两个关键的作用机制结核病的毒力因子，我们将推进预防和治疗结核病的创新方法。