Staphylococcal Adaptations to Platelet Microbicidal Protein

描述(由申请人提供)：来自血小板的抗菌肽(称为血小板杀微生物蛋白)在先天性免疫系统中发挥着关键作用，特别是在宿主防御血管内感染的背景下。在血管内定植期间，入侵的生物体必须与先天免疫系统的这一分支竞争，才能在这些感染部位生存和增殖。生物体可以绕过PMPs的影响在血管内空间生存的机制还不是很清楚。尤其是“适应性反应”，使易受PMP感染的生物体能够在暴露于这些多肽的环境中存活下来。这项提议将采用三个综合的特定目标来解决我们的总体假设：血管内病原体(如金黄色葡萄球菌)的细胞膜能够通过一系列协调的脂质生物合成适应，即被称为“同源粘性适应”，对PMP暴露做出反应并存活下来。三个具体目标将是：1)在体外充分表征同质粘性细胞膜的反应；2)在体外模拟定制脂质体中的同质粘性变化；以及3)确定体内相关生物材料和血管内病变是否发生同质粘性适应。目的1将利用一系列体外技术来检测同源粘性反应，包括膜脂肪酸和磷脂分布、磷脂不对称性和膜流动性。此外，我们将把这些分析与一系列优先考虑的膜脂生物合成基因的表达的时间评估配对。在目标2中，我们将使用大的单层囊泡，其膜脂含量将反映目标1在体外出现的那些。这些研究将定义和量化同源粘性适应对PMP的影响：膜相互作用。目的3将使用体外生物基质模型和兔心内膜炎模型来探索体内同种粘性适应的相关性。一个重要生物事件的体外-体外-体内方面的融合很可能使创新策略的设计成为可能，以防止有机体进化这些适应。这种转换方法在NIH的广泛研究路线图的任务范围内。Laye摘要。这项提案中的研究试图了解细菌如何承受宿主防御系统的重要部分(天然多肽抗生素)的暴露。这可能会使设计出杀死这种细菌的新策略成为可能。

DESCRIPTION (provided by applicant): Antimicrobial peptides from platelets (termed platelet microbicidal proteins [PMPs]) play a critical role in the innate immune system especially in the context of host defenses against endovascular infections. During endovascular colonization, the invading organism must contend with this limb of the innate immune system to persist and proliferate at such sites of infection. The mechanisms by which the organism can circumvent the effects of PMPs to survive within the endovascular space are not well understood. This is especially true of "adaptive responses" that enable PMP-susceptible organisms to survive exposures to these peptides. This proposal will employ three integrated specific aims to address our overall hypothesis: the cell membranes of endovascular pathogens such as Staphylococcus aureus are able to respond to and survive PMP exposures by a coordinated series of lipid biosynthetic adaptations, termed "homeoviscous adaptations". The three specific aims will be: 1) to fully characterize the homeoviscous cell membrane responses in vitro; 2) to model these homeoviscous changes within customized liposomes ex vivo; and 3) to determine whether homeoviscous adaptations occur within relevant biomatrices and endovascular lesions in vivo. Aim 1 will utilize a series of in vitro techniques to examine the homeoviscous responses, including membrane fatty acid and phospholipid profiling, phospholipid assymetry and membrane fluidity. In addition, we will pair these analyses with a temporal assessment of expression by a series of prioritized membrane lipid biosynthetic genes. In Aim 2, we will employ large unilamellar vesicles whose membrane lipid contents will mirror those that emerge in vitro from Aim 1. These studies will define and quantify the impacts of homeoviscous adaptations on PMP:membrane interactions. Aim 3 will use the ex vivo biomatrix model and the rabbit model of endocarditis to explore the in vivo relevance of homeoviscous adaptations. The merging of in vitro-ex vivo-in vivo aspects of an important biologic event may well enable design of innovative strategies to prevent the organism from evolving these adaptations. This translational approach is within the mission of the NIH for their broad research roadmap. Lay Summary. The research in this proposal seeks to understand how bacteria can withstand the exposures to an important part of the host defense system (natural peptide antibiotics). This may enable design of new of strategies to kill such bacteria.