Mechanisms of Staphylococcal Co-Resistance to Daptomycin and Host Defense Peptide

葡萄球菌对达托霉素和宿主防御肽的共耐药机制

• 批准号: 8370376
• 负责人: ARNOLD S BAYER
• 金额: $ 35.4万
• 依托单位: LUNDQUIST INSTITUTE FOR BIOMEDICAL INNOVATION AT HARBOR-UCLA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-12-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8370376
• 关键词: Address; Antibiotics; Antimicrobial Cationic Peptides; Antisense RNA; Applications Grants; Binding; Biochemical; Blood Platelets; Calcium; Cell membrane; Charge; Clinical; Consensus; Daptomycin; Development; Event; Evolution; Exhibits; Exposure to; Frequencies; Future; Gene Expression; Gene Mutation; Genes; Genetic Polymorphism; Host Defense; Hydrophobicity; In Vitro; Individual; Infection; Infective endocarditis; Light; Mediating; Methicillin Resistance; Modeling; Molecular; Molecular Profiling; Multi-Drug Resistance; Mutation; Pathogenesis; Peptides; Phenotype; Phospholipids; Plasmids; Proteins; R peptide; Relative (related person); Reporting; Resistance; Role; Schedule; Seminal; Serial Passage; Site; Staphylococcus aureus; Structure; Surface; Syndrome; System; Time; Tissues; Treatment Protocols; Treatment outcome; Virulence; antimicrobial; attributable mortality; design; gene function; in vivo; methicillin resistant Staphylococcus aureus; novel; resistance factors; resistant strain; response

DESCRIPTION (provided by applicant): S. aureus (SA) causes a wide spectrum of clinical syndromes, and is the leading cause of endovascular infections world-wide. SA has a particular propensity to develop multi-drug resistance, and serious infections with such strains result in enhanced attributable mortalities. Since FDA approval in 2003, daptomycin (DAP) has been utilized in many clinical settings, especially for recalcitrant methicillin-resistant SA (MRSA) infections. There have been numerous recent reports of clinical SA strains that have evolved in vitro DAP-resistance in the context of failing DAP treatment regimens, especially in endovascular infections. One consistent feature of DAP-R strains is the acquisition of one or more "gain-in-function" mutations in a relatively restricted cadre of genes, especially mprF (multiple peptide resistance factor gene). This gene is responsible for the synthesis and translocation ("flipping") of the SA-unique, positively-charged phospholipid (PL), lysyl-phosphotidylglycerol (L-PG) within its cell membrane (CM). Thus, mprF contributes substantially to the relative positive surface charge of SA. Moreover, in light of the absolute requirement for calcium association for DAP's bacterial lethality, genes such as mprF that impact surface charge are highly likely to be important in DAP-R, potentially via charge repulsion. A seminal feature of both clinical and in vitro-derived DAP-R SA strains is the frequent cross-resistance between DAP and cationic host defense peptides (HDPs) (13,15,17-19). Thus, our central hypothesis is that the development of DAP- R in MRSA is frequently associated with the co-evolution of HDP resistance, and this event impacts endovascular pathogenesis and treatment outcomes in vivo. We will address a number of important questions: i) how often do mprF gain-in-function mutations accompany DAP-HDP cross-resistance phenotypes?; ii) are such mprF mutations biased towards the synthase or flippase domains of this gene, and are they causal in cross-resistance?; iii) are there HDP- specific structural features that are shared amongst those peptides which exhibit the DAP-HDP cross-resistance phenotype?; iv) does the temporal exposure "schedule" of S. aureus strains to DAP and/or HDPs influence the development of cross-resistance?; and vi) what are the in vivo consequences of mprF mutations and DAP-HDP cross resistances upon innate virulence and responses to DAP therapy? We anticipate that these studies will contribute to a deeper understanding of the interactive role of our innate host defense system with exogenously administered antimicrobials in stimulating the adaptive survival response in SA. This should enable 'smart design' of future novel anti-SA agents that circumvent this adaptive response. PUBLIC HEALTH RELEVANCE: This proposal seeks to understand the phenotypic and genotypic paradigms that underlie the ability of Staphylococcus aureus (SA) to concomitantly survive potential lethality of exogenous and endogenous cationic antimicrobial peptides. We will focus on the important anti-SA cationic lipopeptide antibiotic, daptomycin, in this regard. We aim to understand the molecular mechanisms by which SA adaptively responds to these classes of peptides as a way to facilitate future design of anti-SA antimicrobials.

描述（由申请人提供）：S。金黄色葡萄球菌（SA）引起广泛的临床综合征，并且是全世界血管内感染的主要原因。SA具有发展多药耐药性的特殊倾向，并且此类菌株的严重感染导致可归因死亡率增加。自2003年FDA批准以来，达托霉素（DAP）已用于许多临床环境，特别是用于顽固性甲氧西林耐药金黄色葡萄球菌（MRSA）感染。最近有许多关于临床SA菌株在DAP治疗方案失败的背景下，特别是在血管内感染中，在体外发展出DAP耐药性的报告。DAP-R菌株的一个一致特征是在相对有限的基因骨干中获得一个或多个“功能获得性”突变，特别是mprF（多肽抗性因子基因）。该基因负责其细胞膜（CM）内SA独特的正电荷磷脂（PL）、赖氨酰-磷脂酰甘油（L-PG）的合成和易位（“翻转”）。因此，mprF实质上有助于SA的相对正表面电荷。此外，鉴于DAP细菌致死性对钙缔合的绝对要求，影响表面电荷的基因如mprF极有可能在DAP-R中重要，可能通过电荷排斥。临床和体外衍生的DAP-RSA菌株的重要特征是DAP和阳离子宿主防御肽（HDPs）之间频繁的交叉抗性（13，15，17 -19）。因此，我们的中心假设是MRSA中DAP-R的发展通常与HDP耐药性的共同进化相关，并且该事件影响体内血管内发病机制和治疗结局。我们将解决一些重要的问题：i）mprF功能获得性突变伴随DAP-HDP交叉抗性表型的频率如何？ii）这种mprF突变是否偏向于该基因的合酶或翻转酶结构域，它们是否是交叉抗性的原因？iii）在表现出DAP-HDP交叉抗性表型的那些肽之间是否存在共有的HDP特异性结构特征？iv）S的时间暴露“时间表”是否是S.金黄色葡萄球菌菌株对DAP和/或HDPs的交叉耐药性影响的发展？和vi）mprF突变和DAP-HDP交叉抗性对先天毒力和对DAP治疗的应答的体内后果是什么？我们预计，这些研究将有助于更深入地了解我们的先天宿主防御系统与外源性抗菌药物在刺激SA的适应性生存反应的相互作用。这将使未来的新型抗SA剂，规避这种适应性反应的“智能设计”。 公共卫生相关性：该提案旨在了解金黄色葡萄球菌（SA）伴随外源性和内源性阳离子抗菌肽的潜在致死性生存能力的表型和基因型范例。在这方面，我们将重点关注重要的抗SA阳离子脂肽抗生素达托霉素。我们的目标是了解SA适应性地响应这些肽类的分子机制，以促进未来抗SA抗菌剂的设计。