Molecular mechanisms of pathogen recognition by the Nod-like receptor NLRC4

Nod样受体NLRC4识别病原体的分子机制

• 批准号: 7791174
• 负责人: Fayyaz S. Sutterwala
• 金额: --
• 依托单位: IOWA CITY VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7791174
• 关键词: Acute; Antibiotic-resistant organism; Antibiotics; Bacteremia; Bacteria; Bacterial Typing; Biology; Burn injury; C Type Lectin Receptors; Caspase-1; Cell Death; Cell membrane; Cells; Collaborations; Complex; Cysteine Protease; Cytosol; Environment; Event; Family member; Flagellin; Gram-Negative Bacteria; Immune; Immune response; Immune system; Immunologic Receptors; Infection; Inflammation; Inflammatory Response; Interleukin-12; Interleukin-18; Invaded; Lead; Legionella; Legionella pneumophila; Ligands; Light; Location; Mediating; Medical Device; Membrane; Mission; Modeling; Molecular; Morbidity - disease rate; Multi-Drug Resistance; Multiprotein Complexes; Mus; Nosocomial Infections; Opportunistic Infections; Organism; Pathogenesis; Pathway interactions; Patient Care; Pattern; Pattern recognition receptor; Pneumonia; Population; Predisposition; Prevalence; Principal Investigator; Process; Production; Pseudomonas; Pseudomonas aeruginosa; RNA Helicase; Reactive Oxygen Species; Relative (related person); Role; Salmonella; Salmonella typhimurium; Shigella; Shigella flexneri; Signal Pathway; Signal Transduction; Specificity; Sterility; Stimulus; Stress; System; TLR5 gene; Toll-like receptors; Transfection; Universities; Ventilator; caspase-3; combat; cystic fibrosis patients; cytokine; experience; in vivo; intraperitoneal; macrophage; monomer; mortality; mutant; neutrophil; new therapeutic target; novel; pathogen; patient population; programs; public health relevance; receptor; resistant strain; response; secretion process; sensor; superinfection

DESCRIPTION (provided by applicant): Project Summary Pseudomonas aeruginosa causes a variety of acute infections, such as ventilator-associated pneumonias, burn superinfections, neutropenic bacteremia, and medical device-related infections. In addition, P. aeruginosa chronically infects cystic fibrosis patients and causes significant morbidity and mortality in this population. With the increasing prevalence of antibiotic resistant organisms, developing agents that will modulate host immune responses will be key adjunctive treatments to conventional antibiotics in combating pathogens such as P. aeruginosa. In order to do this a detailed understanding of the innate immune pathways involved in recognition of pathogens such as P. aeruginosa are required. In this proposal we will examine the role of the NOD-like receptor (NLR) family member NLRC4 in recognition and response to infection with P. aeruginosa. In macrophages NLRC4 is activated in a multiprotein complex called the inflammasome upon infection with a wide variety of Gram-negative bacteria. The activation of the NLRC4 inflammasome ultimately results in the activation of the cysteine protease caspase-1 and its processing and secretion of proinflammatory cytokines. P. aeruginosa activates caspase-1 in an NLRC4-dependent manner leading to macrophage cell death and the release of interleukin (IL)-12 and IL-18. NLRC4-deficient mice also demonstrate increased susceptibility to infection with P. aeruginosa in vivo. In addition to Pseudomonas, other Gram-negative bacteria such as Salmonella, Legionella and Shigella have also been found to activate the NLRC4 inflammasome. One factor that is common to all these pathogens, and required for NLRC4 inflammasome activation, is a functional bacterial type III (T3SS) or type IV (T4SS) secretion system. However, it still remains unclear if NLRC4 serves as a cytosolic pattern recognition receptor for bacterial compounds that gain entry into the cytosol of the host cell through T3SS or T4SS, or if it indirectly senses the consequences of plasma membrane damage caused by the bacterial secretion systems. This proposal outlines three novel aims that will examine the molecular mechanism involved in activation of NLRC4: i) Defining the molecular components and cellular location for assembly of the NLRC4 inflammasome. ii) Elucidating the role of Toll-like receptors and reactive oxygen species in the upstream signaling pathways leading to NLRC4 inflammasome activation. iii) Determining if NLRC4 recognizes host plasma membrane components following their disruption by bacterial T3SS. PUBLIC HEALTH RELEVANCE: Project Narrative Pseudomonas aeruginosa causes a wide variety of opportunistic infections, particularly in hospitalized patient populations where it is responsibly for significant morbidity and mortality. P. aeruginosa is among the most common causes of ventilator associated pneumonia and amongst hospital acquired infections carries one of the highest mortality rates. With the increasing prevalence of multi-drug resistant strains on P. aeruginosa our treatment options are diminishing rapidly. Understanding how this pathogen interacts with and evades the immune system will help us identify new therapeutic targets to treat pseudomonal infections and is hence directly relevant to the VA patient care mission. Our studies will focus on how the innate immune pattern recognition receptor NLRC4 is activated by P. aeruginosa. In addition the information gained from the proposed studies will also shed light on the pathogenesis of related Gram-negative organisms.

描述（由申请人提供）： 铜绿假单胞菌可引起多种急性感染，如呼吸机相关性肺炎、烧伤二重感染、血小板减少性菌血症和医疗器械相关性感染。此外，铜绿假单胞菌慢性感染囊性纤维化患者，并导致该人群的显著发病率和死亡率。随着抗生素耐药性生物体的日益普遍，开发将调节宿主免疫应答的试剂将是对抗病原体如铜绿假单胞菌的常规抗生素的关键后续治疗。为了做到这一点，需要详细了解参与识别病原体如铜绿假单胞菌的先天免疫途径。在本研究中，我们将研究NOD样受体（NLR）家族成员NLRC 4在识别和应答铜绿假单胞菌感染中的作用。在巨噬细胞中，NLRC 4在被多种革兰氏阴性细菌感染后在称为炎性体的多蛋白复合物中被激活。NLRC 4炎性体的活化最终导致半胱氨酸蛋白酶半胱天冬酶-1的活化及其促炎细胞因子的加工和分泌。铜绿假单胞菌以NLRC 4依赖性方式激活半胱天冬酶-1，导致巨噬细胞死亡和白细胞介素（IL）-12和IL-18的释放。NLRC 4缺陷型小鼠也表现出对体内铜绿假单胞菌感染的易感性增加。除假单胞菌外，还发现其他革兰氏阴性细菌如沙门氏菌、军团菌和志贺氏菌也能激活NLRC 4炎性小体。所有这些病原体共有的并且NLRC 4炎性小体活化所需的一个因素是功能性细菌III型（T3 SS）或IV型（T4 SS）分泌系统。然而，仍然不清楚NLRC 4是否充当通过T3 SS或T4 SS进入宿主细胞的胞质溶胶的细菌化合物的胞质溶胶模式识别受体，或者它是否间接地感知由细菌分泌系统引起的质膜损伤的后果。该提案概述了三个新的目标，将检查参与NLRC 4激活的分子机制：i）定义NLRC 4炎性体组装的分子组分和细胞位置。ii）阐明Toll样受体和活性氧物质在导致NLRC 4炎性小体活化的上游信号传导途径中的作用。iii）确定NLRC 4是否在宿主质膜组分被细菌T3 SS破坏后识别宿主质膜组分。 公共卫生相关性： 铜绿假单胞菌引起各种机会性感染，特别是在住院患者人群中，它是导致显著发病率和死亡率的原因。铜绿假单胞菌是呼吸机相关性肺炎的最常见原因之一，并且在医院获得性感染中具有最高的死亡率。随着铜绿假单胞菌多药耐药菌株的日益流行，我们的治疗选择正在迅速减少。了解这种病原体如何与免疫系统相互作用并逃避免疫系统将有助于我们确定新的治疗靶点来治疗假单胞菌感染，因此与VA患者护理使命直接相关。我们的研究将集中在如何天然免疫模式识别受体NLRC 4被铜绿假单胞菌激活。此外，从拟议的研究中获得的信息也将阐明相关革兰氏阴性菌的发病机制。