Determinants of Tuberculosis Severity

结核病严重程度的决定因素

• 批准号: 9030009
• 负责人: Hardy Kornfeld
• 金额: $ 54.86万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-15 至 2020-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9030009
• 关键词: Address; Aerosols; Animal Model; Antibiotics; Apoptosis; Apoptotic; Arachidonate 15-Lipoxygenase; Attenuated; Bacillus (bacterium); Bacteria; Bacterial Genes; Binding; Bronchoalveolar Lavage; Bronchoalveolar Lavage Fluid; Candidate Disease Gene; Cause of Death; Cells; Cessation of life; Characteristics; Cleaved cell; Collaborations; Communicable Diseases; Complex; Cytolysis; Data; Disease; Enzymes; Extracellular Matrix; Fibrosis; Genes; Goals; Heart; Hong Kong; Horizontal Disease Transmission; Hospitals; Host Defense; Human; Hydrolase; Immune; Impairment; In Situ; Infection; Inflammation; Inflammatory; Injury; Institutes; Interferons; Intervention; Investigation; Knowledge; Lead; Lesion; Leukotriene B4; Libraries; Ligands; Link; Lung; Mediating; Mediator of activation protein; Membrane; Methods; Modeling; Mus; Mutate; Mycobacterium tuberculosis; Necrosis; Neutrophil Infiltration; Outcome; Pathogenesis; Pathway interactions; Patients; Peptide Hydrolases; Phagocytes; Phenotype; Process; Pulmonary Fibrosis; Pulmonary Inflammation; Pulmonary Tuberculosis; Recruitment Activity; Regulon; Resolution; Role; Sampling; Serine Protease; Severities; Signal Transduction; Site; Source; Sterility; Structure of parenchyma of lung; System; Testing; Time; Tissues; Transforming Growth Factors; Tuberculosis; Virulence; Virulent; Work; adaptive immunity; antimicrobial; base; cell injury; chemotherapy; feeding; gene product; improved; in vivo; killings; lung injury; macrophage; microbicide; mutant; neutrophil; novel therapeutics; pathogen; prevent; public health relevance; receptor; response; success; trafficking; transmission process

 DESCRIPTION (provided by applicant): Tuberculosis (TB) remains a leading cause of death from infection worldwide. The interaction between Mycobacterium tuberculosis (Mtb) and host macrophages (MΦ) lies at the heart of TB pathogenesis. Our preliminary data indicate that virulent Mtb suppresses a host-protective apoptotic response of infected MΦ in order to use these cells as a protected replication niche. After growing to an optimal intracellular bacillary load, Mtb then induces MΦ necrosis that allows bacteria to escape and spread to naïve phagocytes. We propose that infection-induced MΦ necrosis is the predominant source of signals that recruit neutrophils to TB lesions. Neutrophils likely enhance host defense when TB disease is constrained but when Mtb replication is poorly controlled or when conditions exist that reduce the threshold for MΦ necrosis, neutrophils may accumulate in excess of clearance capacity and die in situ. This establishes a feed-forward mechanism for progressive inflammation and lung tissue damage mediated by neutrophil-derived hydrolases. On this basis we plan to identify the bacterial gene(s) required by Mtb to trigger MΦ necrosis and to identify the specific signals linked to MΦ necrosis that lead to the accumulation of neutrophils at sites o TB disease in the lung. Our preliminary data suggest that one or more genes in the Mtb PhoPR regulon are required for this high bacterial load "burst size" MΦ cytolysis. In Aim 1 we will leverage that finding by systematically testing deletion mutants of candidate PhoPR-regulated genes for loss of cytolytic function. These mutants will be generated using state of the art recombineering methods in collaboration with Dr. Christopher Sassetti (UMass). As a complementary approach we will perform an unbiased screen of an Mtb transposon library for the loss of cytolytic function phenotype. Aim 2 investigates the signaling mechanisms linking MΦ necrosis to neutrophil recruitment, here leveraging new knowledge about the role of leukotriene B4 and 12/15-lipoxygenase in recruiting neutrophils to local sites of cell damage. Aim 3 investigates the relationship between neutrophilic inflammation and tissue injury in the mouse aerosol TB model and in samples of bronchoalveolar lavage fluid and cells obtained from pulmonary TB patients made available through collaboration with Dr. Xinchun Chen (Shenzhen Third People's Hospital and Shenzhen-Hong Kong Institute for Infectious Diseases). Based on the linked hypotheses that Mtb-induced MΦ necrosis promotes neutrophil trafficking to the lung and that neutrophils are dominant mediators of tissue injury, this project has the potential to reveal new targets for pathogen and host-directed therapies to limit neutrophilic inflammation and pulmonary impairment in TB.

 描述（由申请人提供）：结核病（TB）仍然是全世界感染死亡的主要原因。结核分枝杆菌（Mtb）和宿主巨噬细胞（MΦ）之间的相互作用是结核病发病机制的核心。抑制受感染 MΦ 的宿主保护性凋亡反应，以便在生长到最佳细胞内后将这些细胞用作受保护的复制生态位。当结核病受到限制时，Mtb 会诱导 MΦ 坏死，使细菌逃逸并扩散到幼稚吞噬细胞，从而将中性粒细胞募集到结核病灶中，从而增强宿主的防御能力。但当 Mtb 复制控制不佳或存在降低 MΦ 坏死阈值的条件时，中性粒细胞可能会积聚超过清除率这建立了由中性粒细胞衍生的水解酶介导的进行性炎症和肺组织损伤的前馈机制，在此基础上，我们计划鉴定 Mtb 触发 MΦ 坏死所需的细菌基因。与 MΦ 坏死相关的特定信号导致中性粒细胞在肺部结核病部位积聚。我们的初步数据表明，Mtb PhoPR 调节子中的一个或多个基因是在目标 1 中，我们将通过系统地测试候选 PhoPR 调节基因的缺失突变体是否丧失细胞溶解功能来利用这一发现。这些突变体将使用最先进的重组工程方法产生。作为一种补充方法，我们将与 Christopher Sassetti 博士合作，对 Mtb 转座子库进行无偏筛选，以检测细胞溶解功能表型的丧失。研究人员利用有关白三烯 B4 和 12/15-脂氧合酶在将中性粒细胞募集到局部细胞损伤部位中的作用的新知识，研究了将 MΦ 坏死与中性粒细胞募集联系起来的信号机制。目标 3 研究了小鼠气溶胶中中性粒细胞炎症与组织损伤之间的关系。与 Dr. 合作提供了结核病模型以及从肺结核患者获得的支气管肺泡灌洗液和细胞样本。陈新春（深圳市第三人民医院和深港传染病研究所）基于 Mtb 诱导的 MΦ 坏死促进中性粒细胞向肺部运输以及中性粒细胞是组织损伤的主要介质的相关假设，该项目具有潜力。揭示病原体和宿主导向疗法的新靶点，以限制结核病中的中性粒细胞炎症和肺损伤。