Pathobiology of Staphyloccocus areus Endocarditis

沙葡萄球菌心内膜炎的病理学

• 批准号: 7738552
• 负责人: Peter Rolf Panizzi
• 金额: $ 13.64万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7738552
• 关键词: Active Sites; Acute; Address; Animals; Antibiotic Resistance; Argatroban; Arts; Autoradiography; Bacteria; Bacterial Adhesion; Bacterial Endocarditis; Bacterial Infections; Behavior; Binding; Biochemical; Blood; Blood Circulation; Blood Platelets; C57BL/6 Mouse; Catheters; Cleaved cell; Clinical; Coagulase; Coagulation Process; Complex; Deposition; Detection; Development; Diagnosis; Disease; Drug Kinetics; Endocarditis; Ensure; Factor XIII; Factor XIIIa; Fibrin; Fibrinogen; Fluorescence; Fluorescence Microscopy; Generations; Goals; Growth; Half-Life; Heart Valves; Histology; Image; Imaging Techniques; Immunology; Incidence; Infection; Injection of therapeutic agent; Label; Literature; Measures; Mediating; Mentors; Molecular; Monitor; Mus; N-terminal; Pathology; Patients; Peptides; Pharmacia brand of estropipate; Phase; Play; Positron-Emission Tomography; Property; Proteins; Prothrombin; Repetitive Sequence; Research; Role; Rolfing; Specificity; Staphylocoagulase; Staphylococcal Infections; Staphylococcus aureus; Surface; Testing; Thrombin; Transglutaminases; Translations; Virulence; Virulence Factors; X-Ray Computed Tomography; analog; base; clinical Diagnosis; crosslink; improved; in vivo; inhibitor/antagonist; insight; molecular imaging; mortality; mouse model; novel; polymerization; prothrombin activator; small molecule; therapeutic target; tomography; tool

DESCRIPTION (provided by applicant): The broad goal of this proposed research is to determine the underlying molecular mechanisms required for S. aureus endocarditis vegetations to develop and to improve diagnosis of endocarditis by the use of state-of-the-art molecular imaging techniques. Acute bacterial endocarditis (ABE) is a potentially deadly disease caused by bacterial infection of heart valves. Coagulase-positive S. aureus infections are the leading cause of ABE and have the highest mortality rates, due to the increased incidence of antibiotic- resistance. S. aureus expresses a unique non-proteolytic prothrombin (ProT) activator, staphylocoagulase that mediates recognition of fibrinogen by the active staphylocoagulase-ProT complex resulting in conversion of fibrinogen to fibrin. Fibrin generation is hypothesized to play a critical role in ABE pathology. Here, novel active site-labeled ProT analogs have been developed for use in Fluorescence Molecular Tomography (FMT) and Positron Emission Tomography fused with Computed Tomography (PET-CT) studies to identify S. aureus ABE, noninvasively in a mouse model of the disease. Our hypothesis is that staphylocoagulase activates ProT, while simultaneously localizing the staphylocoagulase-ProT complex to S. aureus vegetations. The specific recognition of vegetations by these agents would facilitate the identification of new adjunctive therapies targeting fibrin generation and its cross-linking by factor Xllla. Molecular imaging, biochemical, and immunology studies are proposed to test our hypotheses: that these ProT analogs specifically recognize ABE; that factor XIII activation stabilizes the fibrin network during ABE; and that new adjunctive therapies can limit vegetation grow in ABE. Specific Aims are: (i) To determine the localization of active site labeled ProT in vivo during S. aureus ABE by the FMT imaging and fluorescence microscopy; (2) To determine the pharmacokinetics of these labeled prothrombin probes and their efficacy in imaging ABE by PET-CT imaging; (3) To determine whether S. aureus-induces activation of FXIII and fibrin cross-linking during ABE; and (4) To characterize the effect of argatroban on the vegetation development during ABE.

描述（由申请人提供）：这项拟议研究的总体目标是确定金黄色葡萄球菌心内膜炎赘生物发育所需的潜在分子机制，并通过使用最先进的分子成像技术改进心内膜炎的诊断。急性细菌性心内膜炎（ABE）是一种由心脏瓣膜细菌感染引起的潜在致命疾病。凝固酶阳性金黄色葡萄球菌感染是 ABE 的主要原因，并且由于抗生素耐药性发生率增加，死亡率最高。金黄色葡萄球菌表达一种独特的非蛋白水解凝血酶原 (ProT) 激活剂葡萄球菌凝固酶，可介导活性葡萄球菌凝固酶-ProT 复合物对纤维蛋白原的识别，从而将纤维蛋白原转化为纤维蛋白。据推测，纤维蛋白的生成在 ABE 病理学中发挥着关键作用。在此，开发了新型活性位点标记的 ProT 类似物，用于荧光分子断层扫描 (FMT) 和正电子发射断层扫描与计算机断层扫描 (PET-CT) 融合研究，以在小鼠模型中无创地识别金黄色葡萄球菌 ABE 。我们的假设是葡萄球菌凝固酶激活 ProT，同时将葡萄球菌凝固酶-ProT 复合物定位于金黄色葡萄球菌植被。这些试剂对植被的特异性识别将有助于识别针对纤维蛋白生成及其通过因子 XIIIa 的交联的新辅助疗法。分子成像、生化和免疫学研究旨在检验我们的假设：这些 ProT 类似物特异性识别 ABE； XIII 因子激活可在 ABE 期间稳定纤维蛋白网络；新的辅助疗法可以限制 ABE 中的植被生长。具体目标是： (i) 通过 FMT 成像和荧光显微镜确定金黄色葡萄球菌 ABE 期间标记的 ProT 活性位点在体内的定位； (2) 确定这些标记的凝血酶原探针的药代动力学及其通过 PET-CT 成像对 ABE 进行成像的功效； (3) 确定ABE过程中金黄色葡萄球菌是否诱导FXIII激活和纤维蛋白交联； (4) 表征阿加曲班对 ABE 期间植被发育的影响。