Pyomelanin and Legionella pneumophila Infection

黑色素和嗜肺军团菌感染

• 批准号: 7940261
• 负责人: NICHOLAS P CIANCIOTTO
• 金额: $ 22.88万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7940261
• 关键词: Aerosols; Alveolar Macrophages; Animal Disease Models; Area; Assimilations; Biochemical Genetics; Cells; Data; Development; Disease; Epithelial Cells; Epithelium; Genes; Growth; Habitats; Homogentisic Acid; Human; Infection; Inflammation; Invaded; Iron; Label; Laboratories; Lead; Leadership; Legionella; Legionella pneumophila; Legionnaires' Disease; Light; Lung; Lung Inflammation; Mediating; Melanins; Microbe; Microbial Biofilms; Mus; Parasites; Pathogenesis; Pigments; Prevention; Production; Protozoa; Public Health; Research Project Grants; Resistance; Risk; Role; Screening procedure; Siderophores; Staging; System; Testing; Tissues; United States National Institutes of Health; Virulence Factors; Water; Work; disease diagnosis; extracellular; iron (III) reductase; mouse model; mutant; pathogen; programs; public health relevance; uptake

DESCRIPTION (provided by applicant): Legionella neumophila (Lp) is the agent of Legionnaires' disease. It is ubiquitous in natural and man-made water systems, infecting humans after aerosol inoculation. In aquatic habitats, Lp survives in biofilms and as an intracellular parasite of protozoa, and in the lung, it flourishes as an intracellular parasite of alveolar macrophages and epithelia. Iron is vital to Lp growth in extra- and intracellular niches and its ability to cause disease. For twenty years, my laboratory has been involved in deciphering mechanisms by which Lp causes disease and, for fifteen of those years, has served a leadership role in the study of Lp iron acquisition. Previously, we documented that Lp expresses both siderophore (legiobactin)-mediated ferric iron uptake and FeoB-mediated ferrous iron assimilation and that each of these is required for optimal infection of the lung. In the course of screening for genes involved in legiobactin production, we determined that the secreted brown pigment of Lp, a pyomelanin derived from homogentisic acid (i.e., HGA-melanin), confers ferric reductase activity. In light of these data, we hypothesize i) that secreted HGA-melanin promotes Lp iron acquisition by providing ferrous iron for import into the bacterial cell and ii) that this pyomelanin is required for Lp growth within the infected lung. The pursuit of this hypothesis would be the first test of whether HGA-melanin mediated iron reduction is a (general) mechanism for bacterial iron uptake as well as the first direct assessment of the importance of a bacterial melanin, Lp or otherwise, in an animal model of disease. In this R21 , we will utilize purified HGA-melanin and Lp mutants specifically lacking HGA-melanin to i) determine whether or not secreted pyomelanin can mediate iron acquisition and promote bacterial growth under low-iron conditions, ii) determine the importance of pyomelanin for bacterial growth, inflammation, and tissue damage within Lp-infected mouse lungs. The impact of the proposed studies is significant for multiple reasons. First, it will increase our understanding of Lp, which is an important public health concern throughout the world. Second, since many other important pathogens as well as other important environmental microbes secrete HGA-melanin, it will elucidate new paradigms for both iron assimilation and bacterial pathogenesis. Third, it will potentially provide a new type of target for disease diagnosis, treatment, and/or prevention.

描述（由申请人提供）：Neumophila军团（LP）是军团疾病的推动者。它在天然和人造的水系统中无处不在，在接种气溶胶后感染了人类。在水生栖息地中，LP在生物膜和原生动物的细胞内寄生虫中生存，在肺部，它作为肺泡巨噬细胞和上皮的细胞内寄生虫繁荣发展。铁对于细胞内和细胞内壁ni的LP生长至关重要及其引起疾病的能力。二十年来，我的实验室一直参与LP引起疾病的解密机制，并且其中十五年中一直在LP铁的研究中发挥了领导作用。以前，我们记录了LP同时表达了辅助铁载体（Legiobactin）介导的铁摄取和FEOB介导的亚铁同化，并且每一种都是最佳的肺部感染。在筛选涉及legiobactin产生的基因的过程中，我们确定了LP的分泌的棕色色素是一种源自均蛋白酸（即HGA-甲虫）的曲蛋白酶，赋予了铁还原酶活性。鉴于这些数据，我们假设i）分泌的HGA-甲烷蛋白通过提供亚铁铁的进口到细菌细胞和ii）II）促进LP铁的获取，而II）则是感染肺内LP生长所必需的。对这一假设的追求将是HGA-黑色素介导的还原的第一次测试，这是细菌铁吸收的（一般）机制，以及在疾病动物模型中首次直接评估细菌黑色素，LP或其他方式的重要性。在此R21中，我们将利用纯化的HGA-甲烷蛋白和LP突变体，这些突变体特异性缺乏HGA-甲烷蛋白i）确定分泌的脓聚酶是否可以介导铁的获得性并促进低铁条件下的细菌生长，ii）确定倍瘤蛋白在细菌生长，炎症，LP-lp-noungs lp-nung lp-nungs lp-nungs中的损害。拟议研究的影响很大，原因是多种原因。首先，它将增加我们对LP的理解，这是全球重要的公共卫生关注。其次，由于许多其他重要的病原体以及其他重要的环境微生物分泌HGA-甲烷素，因此它将阐明铁同化和细菌发病机理的新范式。第三，它可能会为疾病诊断，治疗和/或预防提供一种新型的目标。