Mechanistic Studies Of The Mode Of Action Of The Staphylococcus aureus LukAB Cyto

描述（由申请人提供）：金黄色葡萄球菌是导致医院和社区感染的最重要的人类病原体之一。治疗方案，以打击S。由于高水平的抗生素耐药性和缺乏有效的疫苗，金黄色葡萄球菌感染是有限的。因此，非常需要开发针对该生物体的有效治疗剂。S.金黄色 这种细菌通过靶向杀死中性粒细胞来避免宿主清除的能力;先天免疫细胞是控制葡萄球菌感染的组成部分。因此，本研究计划的长期目标是了解S。金黄色葡萄球菌来消耗这些关键的吞噬细胞。最近，我们描述了白细胞毒素A/B（LukAB）作为一种毒力因子，在保护S.金黄色葡萄球菌通过靶向和消除这些细胞而免受嗜酸性粒细胞介导的杀伤。此外，我们已经证明，LukAB有助于社区相关的，耐甲氧西林金黄色葡萄球菌（CA-MRSA）的全身传播的小鼠模型的发病机制。我们发现：LukAB在S.金黄色葡萄球菌，有助于多种菌株的细胞毒性，包括甲氧西林敏感和甲氧西林耐药的S.金黄色葡萄球菌不仅负责杀死中性粒细胞，而且还负责杀死单核细胞、巨噬细胞和树突细胞，是在S.金黄色葡萄球菌，它表现出独特的性质，尚未观察到的其他白细胞毒素。基于我们的发现，我们提出了一种模型，LukAB选择性地结合吞噬细胞，导致毒素寡聚化和孔形成，最终导致膜损伤和靶细胞的杀伤。这个应用程序的主要目标是测试这个模型。为此，我们提出三个具体目标。在目的1中，我们计划阐明候选细胞因子对LukAB对吞噬细胞的嗜性的贡献。在目标2中，我们试图定义涉及LukAB介导的毒性的功能区域。最后，在目标3中，我们提出确定LukAB对S的贡献机制。金黄色葡萄球菌体内致病性。为了实现这些目标，我们建议采用多学科的方法，结合分子生物学，遗传学，免疫学和生物化学，以及离体和体内感染模型。了解LukAB如何介导靶向和杀死吞噬细胞的分子细节对于开发新的治疗方法来抑制这种毒素作为对抗S的新方法至关重要。金黄色葡萄球菌感染

DESCRIPTION (provided by applicant): Staphylococcus aureus is one of the most important human pathogens responsible for infections in both hospital and community settings. Therapeutic options to combat S. aureus infections are limited due to the high level of antibiotic resistance and lack of an effective vaccine. Thus, there is a significant need for the development of effective therapeutics against this organism. Critical to the pathogenic success of S. aureus is the ability of this bacterium to avoid clearance by the host via targeted killing of neutrophils; innate immune cells integral to the control of Staphylococcal infections. Thus, the long-term goal of this research program is to understand the mechanism employed by S. aureus to deplete these critical phagocytes. Recently, we have described the leukotoxin A/B (LukAB) as a virulence factor that plays an integral role in protecting S. aureus from neutrophil-mediated killing by targeting and eliminating these cells. In addition, we have demonstrated that LukAB contributes to the pathogenesis of community-associated, methicillin-resistant Staphylococcus aureus (CA-MRSA) in a murine model of systemic dissemination. We have found that: LukAB is conserved in S. aureus, contributes to the cytotoxicity of a variety of strains including methicilln-sensitive and methicillin- resistant S. aureus, is responsible for the killing of not only neutrophls, but also monocytes, macrophages and dendritic cells, is the most divergent member of the bi-component pore-forming family of toxins found in S. aureus, and it exhibits unique properties that have not been observed by the other leukotoxins. Based on our findings, we propose a model whereby LukAB selectively binds to phagocytes resulting in toxin oligomerization and pore-formation, which ultimately leads to membrane damage and killing of the target cell. The primary goal of this application is to test this model. To this end, we propose three Specific Aims. In Aim 1 we plan to elucidate the contribution of candidate cellular factors for LukAB tropism towards phagocytes. In Aim 2 we seek to define functional regions involved in LukAB-mediated toxicity. Lastly, in Aim 3 we propose to determine the mechanism by which LukAB contributes to S. aureus pathogenesis in vivo. To accomplish these Aims, we propose to employ a multidisciplinary approach that combines molecular biology, genetics, immunology, and biochemistry, together with ex vivo and in vivo infection models. Understanding the molecular details of how LukAB mediates targeting and killing of phagocytes is crucial for the development of novel therapeutic modalities to inhibit this toxin as a new approach to combat S. aureus infections.