STAPHYLOCIDAL MECHANISM OF PLATELET MICROBICIDAL PROTEIN

传统上，血小板被认为促进了高血压的发展。 血管内感染，如传染性心内膜炎(LE)，通过提供 血管内皮细胞损伤后黏附表面的循环定植 微生物。相比之下，最近的证据表明，血小板起作用 重要的宿主防御作用对血管内皮细胞的发展 血管内皮细胞损伤部位的感染通过局部分泌内源性 抗微生物肽，称为凝血酶诱导的血小板杀菌剂 蛋白质或TPMP。初步研究显示了以下数据：一)最终淘汰管理计划 在NM浓度下杀死最常见的血管内病原体；ii) 未发生IE的细菌血症患者的微生物菌株显著高于对照组 在体外对TPMP的杀菌作用比菌株更敏感 来自患有IE的细菌血症患者。这表明表型的TPMP- 抗性为有机体提供了一种生存优势， 诱导IE；iii)结束性淘汰管理计划与常规 抗生素对金黄色葡萄球菌的杀灭和生长抑制作用；以及 细菌细胞膜似乎是TPMP诱导的主要靶点 当前提案的总体目的是定义 TPMP对金黄色葡萄球菌的基本杀菌机制 致命性和最常见的血管内感染总原因，由：i) 定量TPMP与葡萄球菌膜的结合；ii)描绘 细菌跨膜电位在葡萄球菌杀灭作用中的作用 最终淘汰管理计划；三)确定最终淘汰管理计划及其后续的膜组件 TPMP的膜通透性和孔形成；以及iv)确定 利用遗传相关研究TPMP耐药的表型机制 来自不同基因组背景的葡萄球菌菌株 TPMP易感性的表型。这些研究可能最终会定义 新的葡萄球菌杀灭靶点或独特的葡萄球菌杀灭机制。这些 研究还将为定义葡萄球菌杀伤力提供坚实的基础 用分子生物学技术研究TPMP的结构域。最终淘汰管理计划还将提供 作为开发具有强效的合成同系物的设计模板 抗菌活性。

Traditionally, platelets have been thought to promote the development of endovascular infections such as infective endocarditis (lE), by providing a adhesive surface upon damaged endothelium for colonization by circulating microorganisms. In contrast, recent evidence suggests that platelets serve an important host defense role against the development of endovascular infections at sites of endothelial damage via local secretion of endogenous microbicidal peptides , termed thrombin-induced platelet microbicidal protein or tPMP. Preliminary studies revealed the following data: i) tPMP kills the most common endovascular pathogens in nM concentrations; ii) microbial strains from bacteremic patients without IE were significantly more susceptible in vitro to the microbicidal action of tPMP than strains from bacteremic patients with IE. This suggested that phenotypic tPMP- resistance provides the organism with a survival advantage as regards induction of IE; iii) tPMP is synergistic in combination with conventional antibiotics in the killing and growth.inhibition of S. aureus ; and iv) the bacterial cell membrane appears to be a primary target for tPMP-induced lethality.The overall purpose of the current proposal is to define the fundamental microbicidal mechanisms of tPMP against S. aureus, the most virulent and commonest overall cause of endovascular infections, by: i) quantifying tPMP binding to the staphylococcal membrane; ii) delineating the role of bacterial transmembrane potential in the staphylocidal actions tPMP; iii) identifying membrane assembly of tPMP and subsequent membrane permeabilization and pore formation by tPMP; and iv) defining the mechanisms of phenotypic tPMP resistance, using genetically-related staphylococcal strains from a common genomic background which differ phenotypically in tPMP susceptibility. These studies may eventually define novel staphylocidal targets or unique staphylocidal mechanisms. These studies will also provide a solid foundation for defining the staphylocidal domains of tPMP by molecular biologic techniques. tPMP will also serve as a design template for development of synthetic congeners with potent antimicrobial activity.