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(申请人提供)：结核病(TB)仍然是全球感染死亡的主要原因。结核分枝杆菌(MTB)与宿主巨噬细胞(M-Φ)之间的相互作用是结核病发病机制的核心。我们的初步数据表明，毒力Mtb抑制感染的MΦ的宿主保护性凋亡反应，以便将这些细胞用作受保护的复制利基。在生长到最佳的细胞内细菌负荷后，结核分枝杆菌会导致MΦ坏死，使细菌得以逃逸并扩散到幼稚的吞噬细胞。我们认为，感染诱导的MΦ坏死是将中性粒细胞招募到结核病变中的主要信号来源。当结核病受到抑制时，中性粒细胞可能会增强宿主防御，但当MTB复制控制不佳或存在降低MΦ坏死阈值的情况时，中性粒细胞可能会积累超过清除能力并在原位死亡。这为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建立了前馈机制。在此基础上，我们计划鉴定结核分枝杆菌触发M-Φ坏死所需的细菌基因(S)，并鉴定与M-Φ坏死相关的特异性信号，这些信号导致中性粒细胞在肺内结核疾病部位聚集。我们的初步数据表明，Mtb PhoPR调节子中的一个或多个基因是这种高细菌负荷“突发大小”的MΦ细胞溶解所必需的。在目标1中，我们将利用这一发现，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。这些突变体将与马萨诸塞州大学克里斯托弗·萨塞蒂博士合作，使用最先进的重组工程方法产生。作为补充，我们将对Mtb转座子文库进行一次无偏见的筛选，以寻找丧失细胞溶解功能的表型。目的2利用白三烯B4和12/15-脂氧合酶在中性粒细胞募集到细胞损伤局部部位的作用的新知识，研究MΦ坏死与中性粒细胞募集的信号机制。目的3通过与深圳市第三人民医院、深圳-香港传染病研究所陈新春博士合作，从肺结核病患者的肺泡灌洗液和细胞标本中，探讨中性粒细胞炎症与组织损伤的关系。基于结核分枝杆菌诱导的MΦ坏死促进中性粒细胞向肺转移以及中性粒细胞是组织损伤的主要介质的相关假设，该项目有可能揭示病原体和宿主指导的治疗的新靶点，以限制结核患者的中性粒细胞炎症和肺损伤。