Molecular mechanisms of C.albicans - leukocyte integrin interactions

白色念珠菌-白细胞整合素相互作用的分子机制

基本信息

批准号：
8099502
负责人：
Dmitry Aleksandrovich Soloviev
金额：
$ 34.62万
依托单位：
CLEVELAND CLINIC LERNER COM-CWRU
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-08-01 至 2013-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8099502
关键词：
Accounting Acquired Immunodeficiency Syndrome Adhesions Affinity Alleles Amino Acid Sequence Animal Model Antifungal Agents Antigens Arthritis Asses Binding Binding Proteins Binding Sites Biological Biological Assay Bone Marrow Transplantation CD18 Antigens Candida Candida albicans Candidiasis Cell Wall Cells Cellular Immunity Centers for Disease Control and Prevention (U.S.)Chemotherapy-Oncologic Procedure Complex Critical Care Data Dendritic Cells Disease Disseminated candidiasis Endocarditis Event Fibrinogen Fungal Proteins Gastrointestinal tract structure Goals Health Hospitals Host Defense Human ITGAM gene ITGB2 gene Immune Immune response Immune system Immunocompromised Host In Vitro Incidence Individual Infection Infective endocarditis Integrins Intensive Care Units Kinetics Lectin Leukocytes Life Ligands Lymphocyte Macrophage-1 Antigen Mass Spectrum Analysis Mediating Membrane Modeling Molecular Mononuclear Leukocytes Morbidity - disease rate Mucous body substance Mus Mycoses Natural Killer Cells Nosocomial Infections Oral cavity Organ Organism Pathogenesis Patients Peptides Phagocytosis Play Premature Birth Prophylactic treatment Protein C Proteins Resistance Respiratory Burst Risk Role Saccharomycetales Sepsis Site Skin Specificity Surface Testing Tissues Transgenic Mice Vagina Virulence adhesion receptor cell type design fungus in vitro Assay in vivo insight killings macrophage mannoproteins microbial microorganism microorganism interaction migration monocyte mortality mutant neutrophil pathogen prevent protective effect receptor receptor binding research study response

项目摘要

DESCRIPTION (provided by applicant): The CDC has estimated that the incidence of fungal infections has increased by 500-fold since 1980. Candida albicans, a common opportunistic fungal pathogen, is the leading cause of invasive fungal disease in immunocompromised individuals; is the major cause of in-hospital infections; and accounts for 20% of all infective endocarditis, which has a mortality rate as high as 70%. The induction of cell-mediated immunity to C. albicans is critical in host defense and the prime task of cells of the innate immune system. Previously, it has been demonstrated that the integrin 1M22 (CD11b/CD18) is the major neutrophil (PMN) receptor involved in C. albicans recognition. The applicant has shown that an activity is released from C. albicans that inhibits PMN adhesion and migration to the fungus. Utilizing two independent affinity approaches, the same single protein responsible for these activities was purified and identified unequivocally as pH-regulated Antigen 1 (Pra1p), also known as Fibrinogen Binding Protein 1, Fbp1, by mass spectrometry and amino acid sequence. Purified Pra1p blocked PMN adhesion to the fungus and prevented PMN-mediated killing of Pra1p-expressing, but not of Pra1p-deficient strains of C. albicans. We hypothesize that the 1M22-Pra1p- fibrinogen interactions are pivotal in C. albicans pathogenesis: fungal-bound Pra1p is a main target of PMN on C. albicans; the soluble form of Pra1p serves as decoy to assist the fungus in escaping host surveillance; and fibrinogen, which interacts not only with Pra1p but also with 1M22, modulates the interactions. To test this hypothesis, the biological significance of these interactions will be assessed in PMN killing assays and in vivo murine models of systemic candidiasis utilizing C. albicans strains, which lack Pra1p and transgenic mice which lack 1M22, and a closely related integrin 1X22 (Aim 1). The effects of soluble Pra1p on these responses will be assays in vitro and in vivo (Aim 2). The role of fibrinogen as a modulator will be investigated biochemically and using mice in which the fibrinogen binding site for 1M22 has been disrupted (Aim 3). The mechanism underlying these interactions will be defined by identifying sites in 1M22 and in C. albicans which mediate their engagement (Aim 4). These studies will provide insights into the basic mechanism underlying C. albicans interactions with the host and may elucidate new strategies to control fungal infections. PUBLIC HEALTH RELEVANCE: Polymorphonuclear leukocytes have been shown to be the primary components of the host's innate immune defenses against C. albicans infections, and the most prominent receptor that they utilize in microbial recognition is integrin 1M22. The applicant has identified Pra1p as the major ligand of 1M22 among fungal proteins. The proposed study will investigate the molecular mechanism of 1M22 - Pra1p interactions in models ex vivo and in vivo in transgenic mice. Data from this study are expected to highlight mechanisms which are involved in fungal-host interactions and to help design new antifungal peptides.

描述（由申请人提供）：CDC估计，自1980年以来，真菌感染的发病率增加了500倍。白色念珠菌是一种常见的机会性真菌病原体，是免疫功能低下个体发生侵袭性真菌病的主要原因；是院内感染的主要原因；占所有感染性心内膜炎的20%，死亡率高达70%。诱导针对白色念珠菌的细胞介导的免疫对于宿主防御至关重要，也是先天免疫系统细胞的首要任务。此前，已证明整合素 1M22 (CD11b/CD18) 是参与白色念珠菌识别的主要中性粒细胞 (PMN) 受体。申请人已经证明，白色念珠菌释放出一种抑制PMN粘附和迁移至真菌的活性。利用两种独立的亲和方法，纯化了负责这些活性的同一个蛋白质，并通过质谱和氨基酸序列明确鉴定为 pH 调节抗原 1 (Pra1p)，也称为纤维蛋白原结合蛋白 1，Fbp1。纯化的 Pra1p 可以阻断 PMN 对真菌的粘附，并阻止 PMN 介导的对表达 Pra1p 的白色念珠菌菌株的杀伤，但不能杀死 Pra1p 缺陷型的白色念珠菌菌株。我们假设 1M22-Pra1p-纤维蛋白原相互作用在白色念珠菌发病机制中至关重要：真菌结合的 Pra1p 是 PMN 对白色念珠菌的主要靶标； Pra1p的可溶形式充当诱饵，帮助真菌逃避宿主的监视；纤维蛋白原不仅与 Pra1p 相互作用，还与 1M22 相互作用，调节相互作用。为了检验这一假设，将在 PMN 杀伤试验和系统性念珠菌病体内小鼠模型中评估这些相互作用的生物学意义，其中使用白色念珠菌菌株（缺乏 Pra1p）和转基因小鼠（缺乏 1M22 和密切相关的整合素 1X22）（目的1）。可溶性 Pra1p 对这些反应的影响将在体外和体内进行测定（目标 2）。纤维蛋白原作为调节剂的作用将通过生化方法并使用 1M22 纤维蛋白原结合位点已被破坏的小鼠进行研究（目标 3）。这些相互作用的潜在机制将通过识别 1M22 和白色念珠菌中介导其参与的位点来定义（目标 4）。这些研究将深入了解白色念珠菌与宿主相互作用的基本机制，并可能阐明控制真菌感染的新策略。公共健康相关性：多形核白细胞已被证明是宿主针对白色念珠菌感染的先天免疫防御的主要组成部分，它们在微生物识别中利用的最重要的受体是整合素 1M22。申请人已鉴定Pra1p为真菌蛋白中1M22的主要配体。拟议的研究将在转基因小鼠离体和体内模型中研究 1M22 - Pra1p 相互作用的分子机制。这项研究的数据预计将突出涉及真菌-宿主相互作用的机制，并帮助设计新的抗真菌肽。