Targeting Staphylococcus aureus Virulence

描述（由申请人提供）： 耐甲氧西林金黄色葡萄球菌（MRSA）已经成为主要的公共卫生威胁，并且甚至在免疫活性成人中与危及生命的感染相关的单克隆（USA 300）在世界范围内的扩展重新集中了对开发治疗这种感染的新疗法的兴趣。治疗抗生素耐药性感染的一种策略是开发针对毒力而不是细菌生长的药物。这种方法被认为是限制耐药性的发展，同时通过允许免疫效应物杀死和清除药物使其无毒的病原菌来增强宿主防御。尽管这种策略在一些主要革兰氏阴性细菌感染的动物模型中取得了成功，但尚未用于治疗MRSA感染。迄今为止，被鉴定为侵袭性MRSA感染所必需的毒力因子在全球范围内部分地由群体感应操纵子agr调节。重要的是，我们最近的工作将载脂蛋白B鉴定为拮抗agr信号传导的先天屏障，这表明宿主对侵袭性感染的防御可以通过阻断agr信号传导来完成。因此，我们建议使用通过筛选> 50，000种化合物鉴定的小分子抑制剂（SMI）来拮抗agr以治疗实验性MRSA感染。将体外筛选结果转化为体内感染成功治疗的一个重要障碍是确定用于溶解这些大部分疏水化合物同时保持药理学效用的适当载体（9）。在初步的数据中，我们表明，两个SMI与环糊精复合作为媒介物表现出优异的体内治疗效果，对群体感应依赖性MRSA感染。本Merit综述的目的是检验以下假设：与环糊精复合的小分子抑制剂在体外减弱毒力，将增强宿主对MRSA感染的体内防御。为了验证这一假设，我们将追求以下具体目标：1）确定与环糊精复合的小分子抑制剂在agr+和Dagr USA 300和USA 400 S中的毒力机制。（2）在agr+和Dagr S.金黄色葡萄球菌感染的小分子抑制剂与环糊精复合的功效和效力，包括与现有抗生素的协同作用;和3）确定先天免疫效应物在杀死和清除agr+和Dagr USA 300和USA 400 S中的功效。用与环糊精复合的小分子抑制剂处理的金黄色葡萄球菌菌株。 公共卫生相关性： S.金黄色葡萄球菌感染是住院退伍军人、长期护理机构中的退伍军人和战斗中受伤的士兵发病和死亡的重要原因。这种病原体的抗生素耐药性正在增加，在社区和医院环境中出现的高毒力抗生素耐药菌株引起了人们对抗生素治疗这种感染的持续有效性的警觉。此外，严重耐药的S。金黄色葡萄球菌感染与显著增加的住院费用相关。因此，药物开发的新方法既可以限制退伍军人的严重感染，又可以帮助退伍军人管理局限制受感染退伍军人的医疗保健费用。

DESCRIPTION (provided by applicant): Methicillin resistant Staphylococcus aureus (MRSA) has emerged as a major public health threat and the expansion worldwide of a single clone (USA300) associated with life threatening infections even in immunocompetent adults has re-focused interest in developing novel therapeutics to treat this infection. One strategy emerging to treat antibiotic resistant infections is to develop drugs that target virulence but not bacterial growth. This approach is postulated to limit the development of resistance while enhancing host defense by permitting immune effectors to kill and clear the pathogenic bacteria rendered avirulent by the drug. Whereas this strategy has had success in a few animal models of primarily gram-negative bacterial infection, it has not been pursued for treatment of MRSA infection. The virulence factors identified to date as essential for invasive MRSA infection are globally regulated in part by a quorum sensing operon, agr Importantly, our recent work identifying apolipoprotein B as an innate barrier that antagonizes agr signaling demonstrates that host defense against invasive infection can be accomplished by blocking agr signaling. Therefore, we propose to use small molecule inhibitors (SMIs) identified by screening >50,000 compounds for antagonism of agr to treat experimental MRSA infections. A significant barrier in translating in vitro screening results to successful treatment of infection in vivo is ascertaining an appropriate vehicle for solubilizing these largely hydrophobic compounds while maintaining pharmacologic utility (9). In preliminary data we show that two SMIs complexed with cyclodextrin as a vehicle demonstrate excellent in vivo therapeutic efficacy against quorum sensing dependent MRSA infection. The goal of this Merit Review is to test the hypothesis that small molecule inhibitors complexed with cyclodextrin that attenuate virulence in vitro will enhance host defense against MRSA infection in vivo. To test this hypothesis, we will pursue the following specific aims: 1) To determine the virulence mechanisms affected by small molecule inhibitors complexed with cyclodextrin in both agr+ and Dagr USA300 and USA400 S. aureus strains; 2) To determine in multiple models of agr+ and Dagr S. aureus infection the efficacy and potency of small molecule inhibitors complexed with cyclodextrin, including synergism with existing antibiotics; and 3) To determine the efficacy of innate immune effectors in killing and clearance of agr+ and Dagr USA300 and USA400 S. aureus strains treated with small molecule inhibitors complexed with cyclodextrin. PUBLIC HEALTH RELEVANCE: S. aureus infections are a significant cause of morbidity and mortality in hospitalized veterans, veterans in long-term care facilities, and in soldiers wounded in combat. Antibiotic resistance is increasing in this pathogen and the emergence of hypervirulent antibiotic-resistant strains in both community- and hospital- settings is raising alarm over the continued efficacy of antibiotics for the treatment of this infection. Moreover, treatment of severe antibiotic resistant S. aureus infections is associated with significantly increased hospital costs. Therefore, novel approaches to drug development could both limit serious infection in veterans and assist the VA in limiting health care costs of infected veterans.