Intracellular sensing of flagellin and innate immunity to Legionella pneumophila

鞭毛蛋白的细胞内传感和对嗜肺军团菌的先天免疫

• 批准号: 7878515
• 负责人: RUSSELL E VANCE
• 金额: $ 32.84万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7878515
• 关键词: Anti-Bacterial Agents; Antibiotics; Applications Grants; Arthritis; Bacteria; Bacterial Infections; Biochemical; Biological Models; Caspase; Caspase-1; Clinical Treatment; Crohn' s disease; Cytosol; Data; Detection; Disease; Event; Exhibits; Family; Flagellin; Genes; Goals; Gram-Negative Bacteria; Growth; Health; Human; Immune; Immune response; Immune system; In Vitro; Individual; Infection; Inflammatory; Knock-out; Knowledge; Lead; Legionella; Legionella pneumophila; Legionnaires' Disease; Mammalian Cell; Maps; Modeling; Molecular; Molecular Machines; Mus; Natural Immunity; Pneumonia; Proteins; Public Health; Relative (related person); Research; Resistance; Role; Signal Pathway; Signal Transduction; Stimulus; System; TLR5 gene; TNF gene; Testing; Tumor Necrosis Factor Receptor; Virulence; Work; base; cell type; design; detector; human disease; in vivo; interest; macrophage; microbial; novel; pathogen; promoter; public health relevance; response; therapeutic target; tool

DESCRIPTION (provided by applicant): The overall goal of this proposal is to understand how mammalian cells detect and respond to the presence of intracellular bacterial pathogens. Despite antibiotics, bacterial infections continue to present a significant public health challenge. Our studies utilize the gram-negative bacterium Legionella pneumophila, the causative agent of a severe pneumonia called Legionnaires' Disease, as a model for understanding how bacterial pathogens interact with macrophages. The virulence of Legionella depends on its ability to survive and grow within macrophages. Previous work has established that two genes (Naip5 and Ipaf) are instrumental in orchestrating cellular defenses that protect macrophages from Legionella infection, but the molecular mechanism by which Naip5/Ipaf confer resistance to Legionella has remained largely mysterious. Naip5 and Ipaf exhibit homology to a large family of cytosolic pathogen- detector proteins called the Nod-like proteins. Our preliminary results suggest that resistance to Legionella depends on rapid triggering of a Naip5/Ipaf-containing inflammasome that occurs upon the detection of bacterial flagellin in the macrophage cytosol. Inflammasome activation is connected to a variety of human diseases, and thus use of Legionella as a model for understanding inflammasome activation will have broad implications for our understanding of human health and disease. We have also made the unexpected observation that Naip/Ipaf are not sufficient to protect macrophages from Legionella, and that in addition, signaling via the tumor necrosis factor receptor is also required. TNF is already an important therapeutic target in the clinical treatment of diseases such as arthritis and Crohn's Disease. Thus, a deeper understanding of the molecular basis by which Naip/Ipaf and TNF collaborate to restrict Legionella growth could possibly be of great relevance to human health and disease. Thus, the specific aims of this grant proposal are: 1. Test the hypothesis that the intracellular presence of bacterial flagellin protein is sufficient to trigger the Ipaf/Naip5-dependent signaling pathways that restrict bacterial growth; map the determinants within flagellin required to trigger Ipaf/Naip5; and using this information, test the hypothesis that flagellin physically interacts with Naip5 and/or Ipaf. 2. Test the hypothesis that Naip5 is critical for macrophage resistance to Legionella by targeted deletion of Naip5 in mice. 3. Test the hypothesis that Naip5/Ipaf signaling protects macrophages by synergizing with TNF signaling. PUBLIC HEALTH RELEVANCE: It is anticipated that results obtained from the above work will permit a deeper understanding of how bacteria cause disease and of what factors lead to successful immune responses to these bacteria. Such knowledge should contribute to rational approaches to designing novel antibacterial therapies.

描述（由申请人提供）：该提案的总体目标是了解哺乳动物细胞如何检测并应对细胞内细菌病原体的存在。尽管有抗生素，但细菌感染仍会引起重大的公共卫生挑战。我们的研究利用了革兰氏阴性菌肺炎肺癌，这是一种称为Legionnaires疾病的严重肺炎的病因，是一种了解细菌病原体如何与巨噬细胞相互作用的模型。军团菌的毒力取决于其在巨噬细胞中生存和生长的能力。先前的工作已经确定，两个基因（NAIP5和IPAF）在编排保护巨噬细胞免受军团菌感染的细胞防御方面发挥了作用，但是NAIP5/IPAF赋予军团菌的抗性的分子机制在很大程度上仍然是神秘的。 NAIP5和IPAF与称为NOD样蛋白的大型胞质病原体检测器蛋白具有同源性。我们的初步结果表明，对军团菌的耐药性取决于在检测到巨噬细胞细胞质中细菌鞭毛蛋白时发生的含Naip5/IPAF的炎症体的快速触发。炎性体激活与多种人类疾病有关，因此使用军团菌作为理解炎症体激活的模型将对我们对人类健康和疾病的理解产生广泛的影响。我们还意外地观察到NAIP/IPAF不足以保护巨噬细胞免受军团菌的影响，此外，还需要通过肿瘤坏死因子受体的信号传导。 TNF已经是关节炎和克罗恩病等疾病的临床治疗中的重要治疗靶点。因此，对NAIP/IPAF和TNF合作以限制军团菌生长的分子基础的更深入了解可能与人类健康和疾病具有很大的相关性。因此，该赠款提案的具体目的是：1。测试假设细菌鞭毛蛋白蛋白的细胞内存在足以触发限制细菌生长的IPAF/NAIP5依赖性信号通路。绘制触发ipaf/naip5所需的鞭毛林中的决定因素；并使用此信息，测试鞭毛蛋白与NAIP5和/或IPAF物理相互作用的假设。 2。检验以下假设：NAIP5对于通过小鼠的靶向缺失对巨噬细胞对军团菌的抗性至关重要。 3。检验NAIP5/IPAF信号传导通过与TNF信号协同保护巨噬细胞的假设。公共卫生相关性：预计从上述工作中获得的结果将使人们更深入地了解细菌如何引起疾病以及哪些因素导致对这些细菌的成功免疫反应。这种知识应有助于设计新型抗菌疗法的合理方法。