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)已经成为一种主要的公共卫生威胁，即使在具有免疫能力的成年人中，与危及生命的感染相关的单个克隆(USA300)的全球扩张也重新引起了人们对开发治疗这种感染的新疗法的兴趣。出现的一种治疗抗生素耐药感染的策略是开发针对毒力而不是细菌生长的药物。这种方法被认为是为了限制耐药性的发展，同时通过允许免疫效应器杀死和清除药物造成的无毒致病菌来增强宿主防御。虽然这一策略在少数主要为革兰氏阴性细菌感染的动物模型中取得了成功，但尚未被用于治疗MRSA感染。到目前为止，侵袭性MRSA感染所必需的毒力因子在全球范围内部分受群体感应操纵子的调节，重要的是，我们最近发现载脂蛋白B是对抗AGR信号的天然屏障，表明宿主对侵袭性感染的防御可以通过阻止AGR信号来实现。因此，我们建议使用通过筛选50,000个化合物来拮抗AGR而确定的小分子抑制剂(SMI)来治疗实验性的MRSA感染。将体外筛选结果转化为体内感染的成功治疗的一个重要障碍是确定一种适当的载体来溶解这些主要疏水的化合物，同时保持药理作用(9)。在初步数据中，我们发现以环糊精为载体的两种SMI对群体感应依赖的MRSA感染具有良好的体内治疗效果。这篇优点综述的目的是验证这样一种假设，即在体外与环糊精复合以减弱毒力的小分子抑制剂在体内可以增强宿主对MRSA感染的防御。为了验证这一假说，我们将追求以下特定目标：1)确定小分子抑制剂与环糊精复合对AGR+及DAGR USA300及USA400菌株的毒力影响的机制；2)在多种AGR+及DAGR金黄色葡萄球菌感染模型中确定小分子抑制剂与环糊精复合的效力和效力，包括与现有抗生素的协同作用；以及3)确定用小分子抑制剂与环糊精复合处理后对AGR+及DAGR USA300及USA400金黄色葡萄球菌的杀伤和清除效果。 公共卫生相关性： 金黄色葡萄球菌感染是住院退伍军人、长期护理机构退伍军人和在战斗中受伤的士兵发病率和死亡率的重要原因。这种病原体的抗生素耐药性正在增加，社区和医院环境中出现的超强毒力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惕。此外，严重耐药金黄色葡萄球菌感染的治疗与显著增加的医院费用有关。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.