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）：疾病预防控制中心估计，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，是免疫强化的个体中侵袭性真菌疾病的主要原因。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％。细胞介导的对白色念珠菌的免疫的诱导对于宿主防御和先天免疫系统细胞的主要任务至关重要。以前，已经证明整联蛋白1M22（CD11b/CD18）是参与白色念珠菌识别的主要嗜中性粒细胞（PMN）受体。申请人表明，从白色念珠菌释放了一种活动，该活动抑制了PMN粘附并迁移到真菌。利用两种独立的亲和力方法，由质谱法和氨基酸序列纯化了负责这些活性的相同单蛋白，并明确地纯化了这些活性的单一蛋白质，并明确鉴定为pH调节的抗原1（PRA1P），也称为纤维蛋白原结合蛋白1，FBP1。纯化的PRA1P阻断了PMN对真菌的粘附，并阻止了PMN介导的表达PRA1P的杀伤，但没有杀死白色念珠菌的PRA1P缺陷菌株。我们假设1M22-PRA1P-纤维蛋白原相互作用在白色念珠菌发病机理中是关键：真菌结合的PRA1P是PMN的主要靶标在白色念珠菌上。 PRA1P的可溶性形式是诱饵，可以协助真菌逃避宿主监视；和纤维蛋白原不仅与PRA1P相互作用，而且与1M22相互作用，都可以调节相互作用。为了检验这一假设，这些相互作用的生物学意义将在PMN杀伤测定法和使用白色念珠菌菌株的全身性念珠菌病的体内鼠模型中评估，这些模型缺乏PRA1P和缺乏1M22的PRA1P和转基因小鼠，并且是密切相关的整合素1X22（AIM 1）。可溶性PRA1P对这些反应的影响将是体外和体内测定（AIM 2）。纤维蛋白原作为调节剂的作用将进行生化研究，并使用小鼠中断了1M22的纤维蛋白原结合位点（AIM 3）。这些相互作用的基础机制将通过识别1M22中的位点以及介导其参与度的白色念珠菌中的位置来定义（AIM 4）。这些研究将提供有关白色念珠菌与宿主相互作用的基本机制的见解，并可能阐明控制真菌感染的新策略。公共卫生相关性：多形核白细胞已被证明是宿主对白色念珠菌感染的先天免疫防御措施的主要组成部分，并且它们在微生物识别中使用的最突出的受体是整合素1M22。在真菌蛋白中，申请人已将PRA1P确定为1M22的主要配体。拟议的研究将研究模型的离体和体内转基因小鼠中1M22 -PRA1P相互作用的分子机制。这项研究的数据有望突出与真菌 - 宿主相互作用有关的机制，并有助于设计新的抗真菌肽。