Role of Staphylococcus aureus alpha-hemolysin in disease

项目摘要 金黄色葡萄球菌是导致血液、下呼吸道、皮肤和软组织感染的主要原因 在美国感染。证明了病原体的广泛组织范围和毒力特性， S.金黄色葡萄球菌还引起骨髓炎、脓毒性关节炎和一系列毒素介导的实体，包括 葡萄球菌中毒性休克综合征，肠毒素引起的胃肠道疾病，并危及生命 由一种表皮毒素家族引起的脱皮。最近的估计表明，S。aureus贡献 仅在美国，每年就有50万人感染，导致1万多人死亡。年度 S的经济负担。在2003年，金黄色葡萄球菌感染达到145亿美元。到目前为止，还没有商业 现有的疫苗，以防止S。金黄色葡萄球菌感染，以及成功靶向这种感染的新型抗菌药物 生物很少。在疾病广泛传播的情况下， 有效，持久的抗感染策略，我们必须获得更详细的了解， S.金黄色葡萄球菌发病机制S.金黄色葡萄球菌α-溶血素（Hla）是一种成孔细胞毒素 在基因组中编码，并由几乎所有的S.金黄色葡萄球菌HLA参与了 肺炎，原发性和复发性皮肤感染，以及败血症，通过其与毒素的ADAM 10的相互作用， 真核受体Hla是正在进行的临床疫苗和被动免疫研究的首要目标。的 本提案的主要目标是全面了解Hla-ADAM 10复合体如何 损伤多种细胞并调节特定宿主组织中的组织修复 微环境，从而增强我们对疾病进展宿主易感性的认识。这 知识将使新型抗毒素疗法能够合理转化，以影响人类疾病。这 该提案基于四个基本发现：1）通过使用细胞类型特异性的ADAM 10敲除 在小鼠中，我们已经分离出Hla对明确定义的疾病中特定组织内单个细胞的影响， states. 2)Hla的作用不仅仅是有毒孔隙形成的产物，而且取决于毒素介导的 激活ADAM 10和天然ADAM 10底物的病理性裂解。3)我们已经证明 感染生理和病理表现是Hla作用于离散细胞的复合物 随着时间的推移，在组织中整合的群体。4)我们已经证明，抗Hla抗体应答是 与对复发性S的保护有关。儿童金黄色葡萄球菌感染。通过研究，揭示了 Hla-ADAM 10复合物导致宿主细胞和组织损伤的精确机制， 集中分析人类对Hla介导的疾病的易感性，我们预计这些研究将使 完善针对Hla的临床试验，并为疾病预防和治疗提供信息 干预同时，这些研究将有助于我们更广泛地了解细菌孔 形成细胞毒素。

PROJECT SUMMARY Staphylococcus aureus is the leading cause of bloodstream, lower respiratory tract, skin and soft tissue infections in the United States. Demonstrating the broad tissue range and virulence properties of the pathogen, S. aureus also causes osteomyelitis, septic arthritis, and a spectrum of toxin-mediated entities including staphylococcal toxic shock syndrome, enterotoxin-induced gastrointestinal disease, and life-threatening desquamation caused by a family of epidermolytic toxins. Recent estimates suggest that S. aureus contributes to half a million infections per year in the United States alone, resulting in over 10,000 deaths. The annual economic burden of S. aureus infection reached $14.5 billion in 2003. To date, there is no commercially available vaccine to prevent S. aureus infection, and novel antimicrobial agents that successfully target this organism have been few. In the context of widespread disease that has been met with a paucity of highly effective, durable anti-infective strategies, it is imperative that we obtain a more detailed understanding of the molecular mechanisms of S. aureus pathogenesis. S. aureus alpha-hemolysin (Hla) is a pore-forming cytotoxin encoded in the genome and expressed by almost all S. aureus strains. Hla contributes to the pathogenesis of pneumonia, primary and recurrent skin infection, and sepsis through its interaction with ADAM10, the toxin's eukaryotic receptor. Hla is a premier target of ongoing clinical vaccine and passive immunization studies. The primary goal of this proposal is to develop a comprehensive knowledge of how the Hla-ADAM10 complex injures a diverse array of cells and modulates tissue repair within the context of specific host tissue microenvironments, thereby enhancing our knowledge of disease progression host susceptibility. This knowledge will enable the rational translation of novel anti-toxin therapies to impact human disease. This proposal is based on four fundamental discoveries: 1) Through the use of cell-type specific ADAM10 knockout mice, we have isolated the effects of Hla on individual cells within specific tissues in well-defined disease states. 2) The actions of Hla are not merely a product of toxic pore-formation, but depend on toxin-mediated activation of ADAM10 and pathologic cleavage of native ADAM10 substrates. 3) We have demonstrated that the physiologic and pathologic manifestations of infection are a composite of Hla action on discrete cell populations, integrated in the tissue over time. 4) We have demonstrated that an anti-Hla antibody response is associated with protection against recurrent S. aureus infection in children. Through studies that reveal the precise mechanism by which the Hla-ADAM10 complex results in host cell and tissue injury, coupled with focused analysis of human susceptibility to Hla-mediated disease, we anticipate that these studies will enable refinement of clinical trials targeting Hla, and inform the approach to disease prevention and therapeutic intervention. Simultaneously, these studies will contribute more broadly to our understanding of bacterial pore forming cytotoxins.