Pulmonary Defenses Against Intracellular Infection

肺部防御细胞内感染

• 批准号: 8495899
• 负责人: Shawn J. Skerrett
• 金额: $ 36.31万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-25 至 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8495899
• 关键词: Address; Alveolar Macrophages; Antimicrobial Resistance; Bacterial Pneumonia; Binding; Blocking Antibodies; Bone Marrow; Breathing; Caspase; Caspase-1; Cell Death; Cells; Cleaved cell; Community Hospitals; Dendritic Cells; Detection; Development; Event; Exhibits; Failure; Flagellin; Goals; Host Defense; Host Defense Mechanism; Host resistance; Human; Immune response; In Vitro; Infection; Inflammatory; Interferons; Interleukin-1; Interleukin-17; Interleukin-18; Interleukins; Knockout Mice; Legionella pneumophila; Legionellosis; Legionnaires' Disease; Ligands; Lower respiratory tract structure; Lung; Lysosomes; Lytic; Marrow; Mediating; Membrane; Modeling; Morbidity - disease rate; Mus; Natural Killer Cells; Nucleotides; Pathogenesis; Pathway interactions; Phagosomes; Phenotype; Play; Pneumonia; Population; Predisposition; Prevention approach; Production; Recovery; Resistance; Resistance to infection; Role; Signal Transduction; Specificity; Stromal Cells; Testing; Toll-Like Receptor 2; Toll-like receptors; Wild Type Mouse; aerosolized; burden of illness; cytokine; human disease; in vivo; leucine-rich repeat protein; macrophage; microbial; monocyte; mortality; neuronal apoptosis inhibitory protein; novel strategies; parasitism; pathogen; receptor; repaired; response; sensor; tissue culture

DESCRIPTION (provided by applicant): Pneumonia is a leading cause of morbidity and mortality. Understanding mechanisms of host defense in the lower respiratory tract is essential for the development of novel strategies to reduce this burden of disease. Legionella pneumophila (Lp) is an important cause of bacterial pneumonia and an intracellular pathogen of alveolar macrophages (AM). Host defense against Lp involves microbial detection by membrane-bound Toll- like receptors (TLRs), which induce pro-inflammatory cytokines, and by cytosolic nucleotide-binding leucine rich repeat proteins (NLRs), which assemble inflammasomes that activates caspase-1. Caspase-1 cleaves interleukin-1¿ (IL-1¿) and IL-18 to the active forms, favors phagosome maturation, and induces lytic cell death (pyroptosis). Recent studies have highlighted the importance of caspase-1 to the resistance of mouse bone marrow-derived macrophages (BMM) to intracellular infection with Lp, but the contribution of inflammasome activation to integrated host defense in vivo has not been studied. Furthermore, the role of caspase-1 in the resistance of human AM to Lp cannot be predicted from studies with other cell populations, as inflammasome function in human AM is uniquely muted. The overall goal of this project is to understand how key bacterial recognition events are integrated into effective immune responses in vivo, and to determine the relevance of these findings for human disease. To achieve this end we have formulated the following specific aims: Specific aim #1. Determine role of inflammasome activation in the resistance of human AM to Lp. This aim will test the hypothesis that muted function of the NLRC4 inflammasome underlies the susceptibility of human AM to parasitism by Lp. This aim will determine the ligand sensitivity of the NLRC4 inflammasome of human AM in comparison with monocytes and murine AM, determine if Lp induces or suppresses inflammasome activation in AM, and determine if stimulation of the NLRC4 inflammasome induces resistance of human AM to Lp. Specific aim #2. Determine the role of the NLRC4 inflammasome in resistance to pneumonic legionellosis. This aim will use knockout mice, a model of airborne infection, and tissue culture studies to test the hypotheses that NLR-mediated resistance to Lp vivo involves both IL-1¿/IL-18-dependent and -independent mechanisms that are cell-specific. Mice with lacking one or more inflammasome component and wild type mice will be exposed to aerosolized Lp and compared for bacterial clearance, cell death, and immune responses. Specific aim #3. Determine the roles of IL-1¿ and IL-18 in resistance to Lp pneumonia. MyD88, an adaptor that mediates signaling from TLRs and IL-1/IL-18 receptors, is required for survival from pneumonic legionellosis, but deficiencies of TLRs do not reproduce the phenotype of MyD88-/- mice. This aim will use knockout mice and blocking antibodies, a model of airborne infection, and tissue culture studies to test the hypothesis that IL-1¿ and IL-18 play key roles in mediating resistance to pneumonic legionellosis by stimulating interferon-? production, IL-17 responses, and directly augmenting macrophage resistance to Lp.

描述（适用提供）：肺炎是发病率和死亡率的主要原因。了解下呼吸道中宿主防御的机制对于制定减少这种疾病燃烧的新策略至关重要。肺炎军团菌（LP）是肺炎细菌和肺泡巨噬细胞（AM）的细胞内病原体的重要原因。对LP的宿主防御涉及诱导促炎性细胞因子的膜结合收缩受体（TLR）的微生物检测，并通过胞质核苷酸结合亮氨酸重复蛋白（NLR）进行了炎症，这些蛋白质（NLR）构成了激活caspase-1的炎症。 caspase-1裂解白介素-1（IL-1¿）和IL-18对活性形式，有利于吞噬体成熟，并诱导裂解细胞死亡（Pyroptoptosis）。最近的研究强调了caspase-1对小鼠骨髓衍生的巨噬细胞（BMM）对使用LP的细胞内感染的耐药性的重要性，但是尚未研究炎性体激活对体内综合宿主防御的贡献。此外，由于人类AM中的炎性体功能是独特的，因此无法从其他细胞群体的研究中预测caspase-1在人类对LP的抗性中的作用。该项目的总体目标是了解关键细菌识别事件如何在体内有效的免疫调查中纳入有效的免疫调查，并确定这些发现与人类疾病的相关性。为了实现这一目标，我们已经制定了以下特定目标：特定目标＃1。确定炎症体激活在人AM对LP的抗性中的作用。该目标将检验以下假设：NLRC4炎症体的静音功能是人类AM对LP寄生虫的敏感性的基础。与单核细胞和鼠AM相比，该目标将确定人类AM的NLRC4炎症体的配体灵敏度，确定LP是否诱导或抑制AM中的炎性体激活，并确定刺激NLRC4炎性炎的刺激是否会影响人类对LP的抗性。特定目标＃2。确定NLRC4炎症体在耐肺化军团抗性中的作用。该目标将使用敲除小鼠，一种空气传播感染的模型和组织培养研究，以测试NLR介导的对LP体内抗性的假设，涉及IL-1？ /IL-18的依赖性和非依赖性机制，这些机制是细胞特异性的。缺乏一个或多个炎性组成分和野生型小鼠的小鼠将暴露于雾化的LP，并比较细菌清除率，细胞死亡和免疫反应。特定目标＃3。确定IL-1¿和IL-18在对LP肺炎耐药性中的作用。 MyD88是一种介导TLR和IL-1/IL-18受体的信号传导的适配器，是肺炎传说中的生存所必需的，但TLR的缺乏并不重现MyD88 - / - 小鼠的表型。该目标将使用基因敲除小鼠和阻断抗体，一种空气传播感染的模型以及组织培养研究来检验以下假设：IL-1？和IL-18在介导对肺炎的肺炎遗传性通过刺激刺激脑膜的耐药性中起关键作用？生产，IL-17反应，直接增强对LP的巨噬细胞抗性。