Inhibitors of S. aureus bNOS for adjunctive therapy

用于辅助治疗的金黄色葡萄球菌 bNOS 抑制剂

基本信息

批准号：
8492028
负责人：
Donald T Moir
金额：
$ 29.05万
依托单位：
MICROBIOTIX, INC
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-07-01 至 2014-08-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8492028
关键词：
Animal Model Anti-Bacterial Agents Antibiotic Resistance Antibiotic Therapy Antibiotics Bacillus (bacterium)Bacillus anthracis Bacteria Bacterial Infections Biochemical Biological Assay Blood Circulation Cell Death Cells Cessation of life Chemicals Chemosensitization Communicable Diseases Community Hospitals Development Dose Drug Design Drug resistance Effectiveness Enzymes Fluorescent Probes Fluoroquinolones Gene Deletion Genes Genus staphylococcus Glycopeptide Antibiotics Glycopeptides Goals Growth Hospitals Host Defense Hydrogen Peroxide Hydroxyl Radical Immune In Vitro Infection Inhibitory Concentration 50 Isoenzymes Lactams Lead Libraries Mediating Membrane Monobactams Nitric Oxide Nitric Oxide Synthase Nosocomial Infections Oxidative Stress Parents Patients Pharmaceutical Preparations Phase Production Reaction Reactive Oxygen Species Reporter Research Resistance Resistance development Respiratory Burst Site Skin Skin Tissue Sodium Chloride Soft Tissue Infections Specificity Staphylococcus aureus Superoxide Dismutase System Therapeutic Toxic effect Toxicology Urban Hospitals bactericide base beta-Lactam Resistance catalase clinically relevant community setting cytotoxicity improved in vivo inhibitor/antagonist innovation killings methicillin resistant Staphylococcus aureus neutrophil novel pathogen preclinical study pressure public health relevance resistant strain screening small molecule soft tissue

项目摘要

DESCRIPTION (provided by applicant): Staphylococcus aureus is a major cause of community and hospital-acquired infections of the skin, soft tissue, and bloodstream. The recent dramatic increase in occurrence of strains resistant to beta-lactam antibiotics (MRSA) has reduced therapeutic options significantly, but most MRSA strains remain sensitive to other bactericidal antibiotics in the fluoroquinolone (FQ) and glycopeptide (GP) classes. Recent research has demonstrated that bactericidal antibiotics stimulate the production of reactive oxygen species (ROS) in bacteria, which contribute to cell death in a manner similar to the host immune oxidative burst. Alleviation of this oxidative stress by the production of nitric oxide (NO) by bacterial NO synthase (bNOS) enhances the survival of several bacterial species, including staphylococci, to antibacterial therapy and to neutrophil killing. Consequently, small molecule bNOS inhibitors will provide an adjunctive therapeutic approach to bolster the effectiveness of antibiotics and neutrophils against MRSA and potentially reduce the selective pressure for development of drug-resistance by increasing the duration of effective circulating levels of antibiotic. Substantial differences between mammalian and bacterial NOS enzymes indicate that selective inhibition of bNOS is feasible. The overall goal of this project is to discover and develop drugs that increase the efficacy of clinically relevant bactericidal antibiotics against pathogenic staphylococci such as MRSA by specifically inhibiting bacterial NO production. Our strategy is to identify small molecule bNOS inhibitors and to develop them into innovative adjunctive therapies that increase the bactericidal activity of FQ, GP, and beta-lactam antibiotics. In preliminary studies, we established proof of concept for bNOS as a novel target for adjunctive therapy by demonstrating that the growth and viability of strains of S. aureus, B. subtilis, and B. anthracis carrying deletions of the bNOS gene were more sensitive to several bactericidal antibiotics than were their wild-type parents. NO in bacterial cells was shown to activate catalase, induce sodA (superoxide dismutase), suppress the Fenton reaction (production of reactive hydroxyl radicals from H2O2), and rescue cells from ROS generated by bactericidal drugs and by the immune oxidative burst. These results indicate that bactericidal drugs can be potentiated by targeting bacterial systems that reduce ROS damage, such as bNOS. In Phase I, we will construct and optimize luminescent, fluorescent, and biochemical primary and secondary screening assays for bNOS inhibitors, apply them to libraries representing >300,000 discrete chemical compounds, confirm the hits, and validate them as potent, selective potentiators of several antibiotics and neutrophils vs. MRSA and other drug- resistant species. The most potent, broadest acting bNOS inhibitors will be characterized to eliminate compounds with off-target activity vs. the 3 mammalian NOS isozymes and cytotoxicity. In Phase II, we will develop the most promising validated hits into lead compounds by optimizing their activity and specificity using rational drug design and evaluate them for efficacy and toxicity in animal models of infection.

描述（由申请人提供）：金黄色葡萄球菌是社区和医院获得的皮肤，软组织和血液感染的主要原因。最近对β-内酰胺抗生素具有抗性菌株（MRSA）的菌株发生的急剧增加显着降低了治疗选择，但是大多数MRSA菌株对氟喹诺酮（FQ）和糖肽（GP）类中的其他杀菌性抗生素仍然敏感。最近的研究表明，杀菌性抗生素刺激细菌中活性氧（ROS）的产生，这与宿主免疫氧化爆发相似，从而导致细胞死亡。通过产生一氧化氮（NO）来缓解这种氧化应激通过细菌NO合酶（BNOS），可以增强包括葡萄球菌在内的几种细菌物种的存活，从而对抗菌治疗和杀害中性粒细胞杀死。因此，小分子BNOS抑制剂将提供一种辅助治疗方法，以增强抗生素和中性粒细胞对MRSA的有效性，并有可能通过增加有效循环抗生素水平的持续时间来降低药物抗药性的选择性压力。哺乳动物和细菌NOS酶之间的实质性差异表明，选择性抑制BNO是可行的。该项目的总体目的是发现和开发药物，从而提高临床相关的杀菌抗生素对病原葡萄球菌（例如MRSA）（例如MRSA）的功效，特别是通过特异性抑制细菌NO的产生。我们的策略是鉴定小分子BNOS抑制剂，并将其发展为创新的辅助疗法，以增加FQ，GP和β-内酰胺抗生素的杀菌活性。在初步研究中，我们通过证明金黄色葡萄球菌，枯草芽孢杆菌和B.炭疽病的菌株的生长和生存能力对BNOS基因的遗传菌株的生长和生存能力更为几种细菌性抗生素，这比其野生抗生素的父母更敏感。细菌细胞中的NO显示可激活过氧化氢酶，诱导苏打（超氧化物歧化酶），抑制芬顿反应（从H2O2中产生反应性羟基自由基），并从杀菌药物产生的ROS和免疫氧化爆发中拯救细胞。这些结果表明，通过靶向减少ROS损伤（例如BNO）的细菌系统，可以增强杀菌性药物。在第一阶段，我们将构建和优化BNO抑制剂的发光，荧光和生化原发性和次要筛选测定法，将它们应用于代表> 300,000个离散化学化合物的图书馆，确认命中，并将其验证为多种抗生素和中性粒细胞和其他抗药性物种的有效，有选择性的实力，并将其视为有效的，有选择性的实力。最有效，最广泛的作用BNO抑制剂将被表征为消除具有脱靶活性的化合物与3个哺乳动物的NOS同工酶和细胞毒性。在第二阶段，我们将通过使用合理的药物设计优化其活性和特异性，并将其评估为感染动物模型中的功效和毒性，从而将最有希望的验证效果开发为铅化合物。