Development of adjunctive therapies directed at S. aureus amidases

针对金黄色葡萄球菌酰胺酶的辅助疗法的开发

• 批准号: 8912086
• 负责人: BLAISE R BOLES
• 金额: $ 22.28万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-03-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8912086
• 关键词: Address; Amidohydrolases; Animal Model; Antibiotic Resistance; Antibiotic Therapy; Antibiotics; Antimicrobial Resistance; Bacteria; Bacterial Infections; Biochemical; Biological Assay; Biology; Blood; Cell Wall; Cells; Chemicals; Cleaved cell; Communicable Diseases; Communities; Data; Development; Drug Formulations; Drug resistance; Endocarditis; Enzymes; Fluorescence Resonance Energy Transfer; Foundations; Frequencies; Funding; Fusidic Acid; Future; Generations; Genetic; Genomics; Genus staphylococcus; Goals; Gram-Positive Bacteria; Growth; Health; Health Care Costs; Human; Implant; In Vitro; Infection; Lead; Libraries; Life; Mediating; Medical Device; Michigan; Microbial Biofilms; Mission; Modeling; Morbidity - disease rate; Names; Organism; Osteomyelitis; Peptides; Peptidoglycan; Phase; Positioning Attribute; Prevalence; Research; Resistance; Resources; Staphylococcus aureus; Structure-Activity Relationship; Surface; Swimming; System; Testing; Therapeutic; Therapeutic Studies; Time; Tissues; Toxic effect; Translating; United States National Institutes of Health; Universities; Validation; Work; amidase; antimicrobial; chemotherapy; clinical application; crosslink; design; drug resistant bacteria; enzyme activity; experience; high throughput screening; improved; in vivo; in vivo Model; inhibitor/antagonist; member; methicillin resistant Staphylococcus aureus; mortality; mutant; novel; novel strategies; novel therapeutics; pathogen; prevent; screening; small molecule; therapeutic target

DESCRIPTION (provided by applicant): Resistance to antimicrobial chemotherapies is a major contributor to morbidity, mortality, and rising healthcare costs. The prevalence of drug-resistant pathogens against conventional antibiotics has been rising over the last several decades. Of great concern is methicillin-resistant Staphylococcus aureus (MRSA), which is rapidly diminishing the available treatment options for S. aureus infections. As drug resistances continue to emerge there is an urgent need to develop alternative therapeutic approaches such as the development of adjunctive therapies to potentiate the activity of existing antimicrobials. Recently we have discovered that amidase activity of cell wall modifying enzymes (named SsaA1 and SsaA2) mediates S. aureus biofilm resistance to the conventional antibiotic fusidic acid. That is, genetic inactivation of ssaA1 or ssaA2 results in sensitivity of biofilms to fusidic acid. This result suggests that small molecules capable of inhibiting SsaA amidase activity could be used as an adjunctive in conjunction with fusidic acid to effectively eliminate S. aureus biofilms. Mutants in ssaA1 also displayed reduced frequency of fusidic acid resistance emergence, suggesting that in addition to rendering biofilm bacteria sensitive to an antimicrobial, small molecule SsaA amidase inhibitors would also reduce the emergence of drug resistant bacteria. SsaA amidases are an ideal target for small molecule therapies because they are located on the outside of cells making them readily accessible and because humans lack peptidoglycan and the associated biosynthetic machinery (including SsaA amidase homologous). The primary goal of this R21 research is to identify chemical inhibitors of SsaA amidase activity and characterize these molecules for use as potential adjunctive therapeutics. To achieve the goal, we propose the following aims: (1) Identify chemical compounds that eliminate SsaA amidase activity via high throughput screening and (2) Elucidate the ability of SsaA chemical inhibitors to sensitize Staphylococcus biofilms to antimicrobial treatment in in vitro and in vivo models of biofilm development. During the next phase of research (R33), we plan on translating our basic findings for clinical applications by investigating chemical optimization of lead compounds, characterizing antimicrobial activity against other gram-positive pathogens, and developing formulation/delivery systems to be tested with in vivo animal models. The PI's experience in S. aureus biology and the strength of the University of Michigan's Center for Chemical Genomics uniquely position us to conduct this research and make profound discoveries.

描述(由申请人提供)：抗菌素化疗的耐药性是导致发病率、死亡率和医疗费用上升的主要因素。在过去的几十年里，对常规抗生素产生抗药性的病原体的流行率一直在上升。最令人担忧的是耐甲氧西林金黄色葡萄球菌(MRSA)，它正在迅速减少可用于治疗金黄色葡萄球菌感染的选择。随着耐药性的不断出现，迫切需要开发替代治疗方法，例如开发辅助疗法，以增强现有抗菌药的活性。最近我们发现，细胞壁修饰酶(命名为SsaA1和SsaA2)的酰胺酶活性介导了金黄色葡萄球菌对常规抗生素呋西地酸的耐药性。也就是说，ssaA1或ssaA2的基因失活导致生物膜对呋西地克的敏感性 酸。这一结果表明，能够抑制SSAA酰胺酶活性的小分子可以作为辅助剂与呋西地酸联合使用，有效地消除金黄色葡萄球菌的生物被膜。SsaA1中的突变体也显示出梭西地酸耐药性的出现频率降低，这表明除了使生物被膜细菌对抗菌剂敏感外，小分子SSAA酰胺酶抑制剂还会减少耐药细菌的出现。SSAA酰胺酶是小分子治疗的理想靶点，因为它们位于细胞的外部，很容易接触到它们，而且因为人类缺乏肽聚糖和相关的生物合成机制(包括SSAA酰胺酶同源)。这项R21研究的主要目标是确定SSAA酰胺酶活性的化学抑制剂，并表征这些分子作为潜在的辅助治疗药物。为了实现这一目标，我们提出了以下目标：(1)通过高通量筛选来鉴定能够消除SSAA酰胺酶活性的化合物；(2)在体外和体内生物膜发育模型中，阐明SSAA化学抑制剂对葡萄球菌生物膜的敏感性。在下一阶段的研究(R33)中，我们计划通过研究先导化合物的化学优化，表征对其他革兰氏阳性病原体的抗菌活性，以及开发用于体内动物模型测试的配方/递送系统，将我们的基本发现转化为临床应用。PI在金黄色葡萄球菌生物学方面的经验和密歇根大学化学基因组学中心的实力使我们能够进行这项研究并做出深刻的发现。