Selective chemical inhibition of agr quorum sensing in Staphylococcus aureus promotes host defense with minimal impact on resistance.
Selective chemical inhibition of agr quorum sensing in Staphylococcus aureus promotes host defense with minimal impact on resistance.
复制标题
DOI：
10.1371/journal.ppat.1004174
复制
发表时间：
2014-06
期刊：
影响因子：
6.7
通讯作者：
Gresham HD
中科院分区：
文献类型：
--
作者：
Sully EK;Malachowa N;Elmore BO;Alexander SM;Femling JK;Gray BM;DeLeo FR;Otto M;Cheung AL;Edwards BS;Sklar LA;Horswill AR;Hall PR;Gresham HD
细菌信号传导系统是对抗抗生素抗性细菌感染（包括由金黄色葡萄球菌引起的那些）的全球健康威胁的主要药物靶标。S.金黄色葡萄球菌是急性细菌性皮肤和软组织感染（SSTI）的主要原因，而群体感应操纵子agr与这些感染有因果关系。是否可以开发有效的agr信号传导的化学抑制剂，以促进宿主对SSTI的防御，同时保护皮肤的正常微生物群尚不清楚。在高通量筛选中，我们鉴定了一种小分子抑制剂（SMI），savirin（S。金黄色葡萄球菌毒力抑制剂），破坏agr介导的群体感应在这种病原体，但不是在重要的皮肤表皮葡萄球菌。采用电泳迁移率变动分析和一种新的AgrA激活报告菌株的机制研究揭示了转录调节AgrA作为病原体内抑制的靶点，防止毒力基因上调。与其对指数期生长（包括皮肤微生物群成员）的最小影响一致，savirin不会引起由常规抗生素诱导的应激反应或膜功能障碍，如转录谱和膜电位和完整性研究所确定。重要的是，savirin在两种小鼠皮肤感染模型中有效，当在感染时或延迟至最大脓肿发展时给药时，减轻组织损伤并选择性促进agr+而不是Δagr细菌的清除。增强宿主防御的机制涉及部分增强巨噬细胞中agr+的细胞内杀伤，但不包括Δagr和低pH。值得注意的是，在体内或体外多次传代后未观察到对savirin抑制agr的抗性或耐受性，在相同条件下，常规抗生素传代后诱导了对生长抑制的抗性。因此，化学抑制剂可以选择性地靶向S. aureus促进宿主防御，同时保留S.表皮和限制抗性发展。需要新的方法来减轻抗生素耐药性细菌感染的负担。一种策略是开发靶向毒力的疗法，这种疗法依赖于宿主防御元件来清除细菌，而不是直接抗菌。群体感应是一种细菌信号传导机制，通常调节医学相关细菌病原体的毒力。因此，抑制群体感应的药物可以通过使病原菌无毒和/或不太适合在宿主内存活来促进宿主防御。我们的工作在病原体金黄色葡萄球菌中解决了这一策略，金黄色葡萄球菌是急性细菌性皮肤和软组织感染的主要原因。我们进行了高通量筛选，以确定化合物，可以抑制信号的群体感应操纵子，agr。我们发现了一种化合物，我们称之为savirin（S。金黄色葡萄球菌毒力抑制剂），可以抑制该操纵子的信号传导。这种药物帮助动物的先天免疫系统清除表达这种操纵子的细菌，而不影响没有这种操纵子的细菌的清除。我们讨论了这种化合物的作用机制，以及是否可能产生对这种化合物的耐药性或耐受性。我们的数据表明，第一次宿主防御S。金黄色葡萄球菌皮肤感染可通过化学抑制AGR介导的群体感应而增强。
Bacterial signaling systems are prime drug targets for combating the global health threat of antibiotic resistant bacterial infections including those caused by Staphylococcus aureus. S. aureus is the primary cause of acute bacterial skin and soft tissue infections (SSTIs) and the quorum sensing operon agr is causally associated with these. Whether efficacious chemical inhibitors of agr signaling can be developed that promote host defense against SSTIs while sparing the normal microbiota of the skin is unknown. In a high throughput screen, we identified a small molecule inhibitor (SMI), savirin (S. aureus virulence inhibitor) that disrupted agr-mediated quorum sensing in this pathogen but not in the important skin commensal Staphylococcus epidermidis. Mechanistic studies employing electrophoretic mobility shift assays and a novel AgrA activation reporter strain revealed the transcriptional regulator AgrA as the target of inhibition within the pathogen, preventing virulence gene upregulation. Consistent with its minimal impact on exponential phase growth, including skin microbiota members, savirin did not provoke stress responses or membrane dysfunction induced by conventional antibiotics as determined by transcriptional profiling and membrane potential and integrity studies. Importantly, savirin was efficacious in two murine skin infection models, abating tissue injury and selectively promoting clearance of agr+ but not Δagr bacteria when administered at the time of infection or delayed until maximal abscess development. The mechanism of enhanced host defense involved in part enhanced intracellular killing of agr+ but not Δagr in macrophages and by low pH. Notably, resistance or tolerance to savirin inhibition of agr was not observed after multiple passages either in vivo or in vitro where under the same conditions resistance to growth inhibition was induced after passage with conventional antibiotics. Therefore, chemical inhibitors can selectively target AgrA in S. aureus to promote host defense while sparing agr signaling in S. epidermidis and limiting resistance development. New approaches are needed to lessen the burden of antibiotic resistant bacterial infections. One strategy is to develop therapies that target virulence which rely on host defense elements to clear the bacteria rather than direct antimicrobial killing. Quorum sensing is a bacterial signaling mechanism that often regulates virulence in medically relevant bacterial pathogens. Therefore, drugs that inhibit quorum sensing can promote host defense by rendering the pathogenic bacteria avirulent and/or less fit for survival within the host. Our work addressed this strategy in the pathogen Staphylococcus aureus which is the major cause of acute bacterial skin and soft tissue infections. We conducted a high throughput screen to identify compounds that could inhibit signaling by the quorum sensing operon, agr. We found a compound that we termed savirin (S. aureus virulence inhibitor) that could inhibit signaling by this operon. The drug helped the innate immune system in animals to clear bacteria that express this operon without affecting clearance of bacteria that do not have this operon. We addressed the mechanism of action of this compound and whether resistance or tolerance to this compound would likely develop. Our data indicate for the first time that host defense against S. aureus skin infections can be enhanced by chemical inhibition of agr-mediated quorum sensing.
登录
查看更多内容
影响因子：
6.7
作者：
Attia AS;Benson MA;Stauff DL;Torres VJ;Skaar EP
通讯作者：
Skaar EP
影响因子：
3.6
作者：
George Cisar EA;Geisinger E;Muir TW;Novick RP
通讯作者：
Novick RP
影响因子：
4.2
作者：
Dengler V;Meier PS;Heusser R;Berger-Bächi B;McCallum N
通讯作者：
McCallum N
影响因子：
3.7
作者：
Malachowa N;Whitney AR;Kobayashi SD;Sturdevant DE;Kennedy AD;Braughton KR;Shabb DW;Diep BA;Chambers HF;Otto M;DeLeo FR
通讯作者：
DeLeo FR
影响因子：
6.7
作者：
Hall PR;Elmore BO;Spang CH;Alexander SM;Manifold-Wheeler BC;Castleman MJ;Daly SM;Peterson MM;Sully EK;Femling JK;Otto M;Horswill AR;Timmins GS;Gresham HD
通讯作者：
Gresham HD