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

• 批准号: 7903419
• 负责人: Dmitry Aleksandrovich Soloviev
• 金额: $ 34.97万
• 依托单位: CLEVELAND CLINIC LERNER COM-CWRU
• 依托单位国家: 美国
• 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/7903419
• 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; 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; 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; public health relevance; receptor; receptor binding; research study; response

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致病真菌，是免疫功能低下个体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%，其死亡率高达70%。诱导抗C.白色念珠菌在宿主防御中至关重要，并且是先天免疫系统细胞的首要任务。整合素1 M22（CD 11b/CD 18）是参与C.白色念珠菌识别申请人已证明某项活动是从C释放的。白念珠菌，抑制中性粒细胞粘附和迁移到真菌。利用两种独立的亲和方法，纯化了负责这些活性的相同单一蛋白，并通过质谱和氨基酸序列明确鉴定为pH调节抗原1（Pra 1 p），也称为纤维蛋白原结合蛋白1，Fbp 1。纯化的Pra 1 p阻断了PMN对真菌的粘附，并阻止了PMN介导的对表达Pra 1 p的C.白色念珠菌我们假设1 M22-Pra 1 p-纤维蛋白原相互作用在C.白念珠菌致病机制：真菌结合的Pra 1 p是白念珠菌上PMN的主要靶点。白色念珠菌;可溶形式的Pra 1 p作为诱饵帮助真菌逃避宿主的监视;而纤维蛋白原不仅与Pra 1 p相互作用，而且与1 M22相互作用，调节相互作用。为了检验这一假设，将在PMN杀伤试验和利用念珠菌的系统性念珠菌病的体内鼠模型中评估这些相互作用的生物学意义。白色念珠菌菌株，其缺乏Pra 1 p和缺乏1 M22的转基因小鼠，以及密切相关的整合素1X 22（Aim 1）。将在体外和体内测定可溶性Pra 1 p对这些应答的影响（目的2）。将使用1 M22的纤维蛋白原结合位点已被破坏的小鼠，从生物化学角度研究纤维蛋白原作为调节剂的作用（目的3）。这些相互作用的机制将通过鉴定1 M22和C中的位点来确定。白念珠菌介导它们的接合（目的4）。这些研究将为深入了解C.白念珠菌与宿主的相互作用，并可能阐明新的战略，以控制真菌感染。公共卫生相关性：多态性白细胞已被证明是宿主先天性免疫防御C。白色念珠菌感染，并且它们在微生物识别中利用的最突出的受体是整合素1 M22。申请人已鉴定Pra 1 p为真菌蛋白中1 M22的主要配体。该研究将在转基因小鼠的离体和体内模型中研究1 M22-Pra 1 p相互作用的分子机制。这项研究的数据预计将突出参与真菌-宿主相互作用的机制，并帮助设计新的抗真菌肽。