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

金黄色葡萄球菌 LukAB Cyto 作用方式的机制研究

• 批准号: 8670695
• 负责人: Victor J. Torres
• 金额: $ 42.38万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-04 至 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8670695
• 关键词: Animal Model; Antibiotic Resistance; Bacteria; Bacterial Infections; Binding; Biochemical; Biochemistry; Cell Death; Cell membrane; Cells; Cellular Assay; Communities; Data; Dendritic Cells; Development; Engineering; Epithelial Cells; Erythrocytes; Exhibits; Family; Functional disorder; Genetic; Goals; Growth; Hospitals; Human; ITGAM gene; ITGB2 gene; Immune; Immune system; Immunology; Infection; Integrins; Intoxication; Knockout Mice; Knowledge; Leukocytes; Life; Light; Mediating; Membrane; Modality; Modeling; Molecular; Molecular Biology; Mus; Mutagenesis; Organism; Pathogenesis; Phagocytes; Play; Process; Property; Protein Sequence Analysis; Publishing; Recruitment Activity; Research; Research Project Grants; Research Proposals; Role; Site; Site-Directed Mutagenesis; Staphylococcal Infections; Staphylococcus aureus; Surface; Systemic infection; Testing; Therapeutic; Toxic effect; Toxin; Tropism; Vaccines; Virulence; Virulence Factors; Whole Blood; base; cell killing; cell type; combat; community setting; cytotoxic; cytotoxicity; defined contribution; improved; in vivo; inhibitor/antagonist; interdisciplinary approach; killings; leukotoxin; macrophage; member; methicillin resistant Staphylococcus aureus; monocyte; mutant; neutrophil; novel strategies; novel therapeutics; pathogen; programs; public health relevance; receptor; renal abscess; selective expression; success

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.

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。由于高度抗生素耐药性和缺乏有效的疫苗，对抗金黄色葡萄球菌感染的治疗选择有限。因此，非常需要开发针对该生物体的有效疗法。金黄色葡萄球菌成功致病的关键是 该细菌通过靶向杀死中性粒细胞来避免被宿主清除的能力；先天免疫细胞对于控制葡萄球菌感染至关重要。因此，该研究计划的长期目标是了解金黄色葡萄球菌消耗这些关键吞噬细胞的机制。最近，我们将白细胞毒素 A/B (LukAB) 描述为一种毒力因子，通过靶向和消除这些细胞，在保护金黄色葡萄球菌免受中性粒细胞介导的杀伤方面发挥着不可或缺的作用。此外，我们还证明 LukAB 在全身传播的小鼠模型中有助于社区相关的耐甲氧西林金黄色葡萄球菌 (CA-MRSA) 的发病机制。我们发现： LukAB 在金黄色葡萄球菌中是保守的，有助于多种菌株（包括甲氧西林敏感和耐甲氧西林金黄色葡萄球菌）的细胞毒性，不仅负责杀死中性粒细胞，还负责杀死单核细胞、巨噬细胞和树突状细胞，是金黄色葡萄球菌中发现的双组分成孔毒素家族中最不同的成员， 它具有其他白细胞毒素未观察到的独特特性。根据我们的发现，我们提出了一个模型，通过该模型，LukAB 选择性地与吞噬细胞结合，导致毒素寡聚化和孔形成，最终导致膜损伤并杀死靶细胞。该应用程序的主要目标是测试该模型。为此，我们提出三个具体目标。在目标 1 中，我们计划阐明候选细胞因子对 LukAB 对吞噬细胞的趋向性的贡献。在目标 2 中，我们试图定义参与 LukAB 介导的毒性的功能区域。最后，在目标 3 中，我们建议确定 LukAB 在体内促进金黄色葡萄球菌发病的机制。为了实现这些目标，我们建议采用多学科方法，将分子生物学、遗传学、免疫学和生物化学与离体和体内感染模型结合起来。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抑制这种毒素的新型治疗方式至关重要，作为对抗金黄色葡萄球菌感染的新方法。