DETERMINANTS IN PLATELET MICROBICIDAL PROTEINS

描述(改编自申请者摘要)：人和兔子 血小板含有血小板杀微生物蛋白(PMPs)。调查人员的 数据显示，PMPs在血小板抗菌功能中起着关键作用。PMP 对具有抗生素耐药性的血液发挥强大的杀菌作用 病原体，包括金黄色葡萄球菌和白色念珠菌。特定的PMP 从暴露于病原体或激动剂的血小板中释放出来 血管内感染，并在这些部位局部加剧。PMP易感 在动物模型中，病原体的毒力低于其同基因的PMP抗性 对口单位。这些令人信服的事实支持了他们的假设 对抗菌宿主防御有显著贡献。PMP的最低要求是 对人血管内皮细胞或红细胞有毒性，且差异显著 在结构和机制上来自不释放的抗菌肽 进入血液中。这些事实表明，PMP具有关键的功能决定因素 在不伴随宿主细胞毒性的情况下优化杀菌活性。 除了它的杀菌作用外，他们还发现PMP-2还 增强中性粒细胞的趋化、吞噬和细胞内杀伤作用。 金星。PMP-2有一个胱氨酸-X-胱氨酸(CXC)基序，与 人血小板因子-4(HPF-4)等可放大的α-趋化因子 中性粒细胞的抗菌机制。这些事实表明，PMP-2是一种 独特的分子，既能直接杀菌，又能发挥杀菌作用 中性粒细胞增强作用。研究人员的中心假说认为 PMP-2具有导致这些不同宿主特定决定因素 防御功能。他们进一步假设这些决定因素可以被定义， 建模并用于建立关键结构-活性关系(SARS) 管理特定职能的。拟议的研究旨在探索 这些假设。在PMP-2功能决定因素中定义SARS对 他们的最终目标是设计出有效和/或 对抗生素耐药病原体的选择性活性。因此，他们的 具体目标是：一)界定负责以下方面的结构性决定因素 PMP-2的直接杀菌功能；II)确定PMP-2的结构 增强中性粒细胞抗微生物功能的决定因素；以及 Iii)确定PMP-2的抗微生物决定因素中的关键SARS。比较 PMP-2和HPF-4决定因素的强效和/或 区别性抗菌功能将使未来对人类PMP的研究成为可能 在兔子模型中，这是不能在人类身上进行的。此外，特区主题 在PMP-2中发现将加速发现新的抗感染药物 对抗对常规药物耐药的病原体的策略。因此，这些 研究将大大促进我们对抗菌宿主的理解 防御，并可能为其放大产生新的模式。

DESCRIPTION (Adapted from the Applicant's Abstract): Human and rabbit platelets contain platelet microbicidal proteins (PMPs). The investigators' data show that PMPs play key roles in platelet antimicrobial functions. PMPs exert potent microbicidal actions against antibiotic-resistant bloodstream pathogens, including Staphylococcus aureus and Candida albicans. Specific PMPs are released from platelets exposed to pathogens or agonists at sites of endovascular infection, and intensify locally at these sites. PMP-susceptible pathogens are less virulent in animal models than their isogenic PMP-resistant counterparts. These compelling facts support their hypothesis that PMPs significantly contribute to antimicrobial host defense. PMPs are minimally toxic to human vascular endothelial cells or erythrocytes, and differ markedly in structure and mechanism from antimicrobial peptides that are not released into the bloodstream. These facts suggest PMPs have key functional determinants that optimize microbicidal activity without concomitant host cytotoxicity. Beyond its microbicidal effects, they have discovered that PMP-2 also potentiates neutrophil chemotaxis, phagocytosis and intracellular killing of S. aureus. PMP-2 has a cystine-X-cystine (CXC) motif distinctive of alpha-chemokines such as human platelet factor-4 (hPF-4) that amplify antimicrobial mechanisms of neutrophils. These facts indicate that PMP-2 is a unique molecule that exerts both direct microbicidal and neutrophil-potentiating effects. The investigators' central hypothesis contends that PMP-2 has specific determinants responsible for these distinct host defense functions. They further hypothesize these determinants can be defined, modeled, and used to establish key structure-activity relationships (SARs) governing specific functions. The proposed studies are designed to explore these hypotheses. Defining SARs in PMP-2 functional determinants is crucial to their eventual goal of designing anti-infective agents with potent and/or selective activity against antibiotic-resistant pathogens. Therefore, their Specific Aims are: i) to define the structural determinants responsible for direct microbicidal functions of PMP-2; ii) define the PMP-2 structural determinants that potentiate the antimicrobial functions of neutrophils; and iii) establish the key SARs in antimicrobial determinants of PMP-2. Comparison of PMP-2 and hPF-4 determinants responsible for their potent and/or discriminative antimicrobial functions will enable future studies of human PMPs in the rabbit model that cannot be conducted in humans. Moreover, SAR themes discovered in PMP-2 will accelerate discovery of novel anti-infective strategies against pathogens resistant to conventional agents. Thus, these studies will significantly advance our understanding of antimicrobial host defense, and may yield new modes for its amplification.