Selective Agents to Block Virulence in Gram-negative Pathogens

描述（由申请人提供）：细菌抗生素耐药性的急剧上升是一个严重的问题，特别是在革兰氏阴性病原体中，增加了发病率、死亡率和医疗费用。尽管一个多世纪以来，人们一直在努力杀死致病菌，但这些微生物已经开发出了越来越多的创新方法，来克服我们能够生产的最好的药物。越来越多的证据表明，一种旨在抑制毒力而不抑制生长本身的不同方法可以预防或治愈疾病，而不会不可避免地导致耐药性。我们的长期目标是开发能够选择性地预防细菌病原体毒性发作的方法。我们的目标是开发选择性抑制剂，阻断革兰氏阴性人类病原体的毒力并抑制生物膜的形成，而不会干扰其生长。我们的中心假设是，通过改变群体感应（QS）分子的共同前体，可以选择性地抑制触发毒力反应的群体感应（QS）分子的生物合成，而不影响细菌代谢的基本方面。由于这些生物将保持活力，但功能无毒，因此对QS抑制的抗性选择压力要弱得多。我们计划通过以下互补的初始具体目标来实现我们的项目目标：(1)设计和测试选择性阻断QS分子产生的目标酶的替代底物和抑制剂；(2)利用新的筛选方法在更大范围内鉴定QS抑制剂。一旦这些目标实现，我们将进入该项目的第二阶段，其中包括：(1)将我们的群体感应抑制剂的开发重点放在特定的致病物种上；(2)测试这些抑制剂协同提高目前使用的抗生素有效性的能力。我们提出的研究的贡献将是开发一种方法，在最大限度地减少细菌耐药性的选择的同时，产生新的药物。这项工作意义重大，因为它旨在验证一种不依赖微生物死亡来克服细菌感染的替代方法。

DESCRIPTION (provided by applicant): The spectacular rise of bacterial antibiotic resistance is a serious problem, particularly among Gram-negative pathogens, increasing morbidity, mortality and healthcare costs. Despite over a century of intense effort focused on killing pathogenic bacteria, these organisms have developed and shared increasingly inventive ways to overcome the best drugs we have been able to produce. There is growing evidence that a different approach, aimed at inhibiting virulence without inhibiting growth per se, can prevent or cure disease without inevitably leading to resistance. Our long term goal is to develop approaches that will selectively prevent the onset of virulence in bacterial pathogens. Our objective for this application is to develop selective inhibitors that block virulence and inhibit biofilm formation in Gram-negative human pathogens without otherwise interfering with their growth. Our central hypothesis is that biosynthesis of the quorum sensing (QS) molecules that trigger a virulence response can be selectively inhibited, without affecting the essential aspects of bacterial metabolism, by altering the common precursor for these QS molecules. Because these organisms will remain viable, but functionally avirulent, there will be much weaker selective pressure for resistance to QS inhibition. We plan to accomplish our project goals through the following complementary initial specific aims: (1) design and test alternative substrates and inhibitors for target enzymes that selectively block the production of QS molecules; and (2) use a new screening method to identify QS inhibitors on a broader scale. Once these aims have been achieved we will move to Phase II of this project, which involves: (1) focusing our quorum sensing inhibitor development towards specific pathogenic species; and (2) testing the ability of these inhibitors to synergistically increase the effectiveness of currently used antibiotics. The contribution of our proposed research will be the development of an approach that leads to new drugs while minimizing selection for bacterial resistance. This work is significant because it is designed to validate an alternative approach that does not rely on microbial death to overcome bacterial infections. PUBLIC HEALTH RELEVANCE: Mortality from infections is the second leading cause of death worldwide, and is still the third leading cause in industrialized countries. The major threat comes from bacterial pathogens that have evolved resistance to most classes of antibiotics. An approach that can block virulence in Gram-negative bacteria while minimizing selection for resistance will lead to a new paradigm in the treatment of infections.