Novel cyclic lipopeptides for treating gram negative bacterial infections

 描述(申请人提供)：住院患者发生多药耐药(MDR)细菌感染的风险很高。根据美国传染病学会的数据，革兰氏阴性病原体，如铜绿假单胞菌、鲍曼不动杆菌和产超广谱β-内酰胺酶的肠杆菌科细菌，因其高归因性死亡率和独特的毒力或耐药因素而特别成问题。由这些病原体引起的感染非常难以治疗，因为抗生素耐药性和生物膜的形成对宿主防御和抗菌治疗具有耐药性。细菌生物膜是治疗慢性伤口感染的关键挑战。慢性伤口特别容易发生感染，细菌生物膜与伤口感染和伤口无法愈合有关。鉴于这一问题的严重性，迫切需要新的抗生素来对抗耐药革兰氏阴性菌，并能够调节细菌生物膜的形成和维持，以满足发现新的局部应用和有效对抗耐多药革兰氏阴性菌的抗菌剂的需求，包括它们的生物膜，我们建议设计和合成基于Fusaricidin/Li-F天然产物的新型环状脂肽。我们最近的突破性发现表明，这些环状脂肽的总疏水性和净正电荷的增加提高了它们对革兰氏阴性菌的活性。由于先导肽3在体外和体内对铜绿假单胞菌和鲍曼不动杆菌生物被膜显示出良好的活性，因此在抗细菌生物被膜的活性方面效果尤其明显。重要的是，结构变化导致更多的疏水性和正电荷的类似物并不会导致非特异性毒性的增加。在这项建议中，我们的总体目标是进一步修饰环脂肽3，以优化其抗菌/抗生物膜活性，并将非特异性毒性降至最低。在R21阶段，我们将利用组合化学结合筛选试验来鉴定对浮游生物和生物膜具有高效力、耐多药革兰氏阴性细菌和低非特异性毒性的环状脂肽先导。在R33阶段，我们将：a)开发基于明胶水凝胶的局部应用的最佳给药系统，b)确定这些多肽的作用模式，以及c)评估优化的多肽/水凝胶配方在猪伤口感染模型中的治疗潜力。一旦完成，这项拟议的研究将导致一类新的抗菌肽用于局部应用，可以推进到临床研究。一旦完成，这项拟议的研究将导致一类新的抗菌肽用于局部应用，可以推进到临床研究。

 DESCRIPTION (provided by applicant): Hospitalized patients are at high risk for developing infections caused by multidrug-resistant (MDR) bacteria. According to the Infectious Diseases Society of America MDR Gram-negative pathogens such as P. aeruginosa, A. baumannii and extended-spectrum b-lactamase producing Enterobacteriaceae are especially problematic with high attributable mortality rates, and unique virulence or drug-resistance factors. Infections caused by these pathogens are exceedingly difficult to treat due antibiotic resistance and formation of biofilms that are resistant to host defense and antimicrobial treatments. Bacterial biofilms are a key challenge in treating chronic wound infections. Chronic wounds are particularly susceptible to the development of infections and bacterial biofilms are implicated in both the infection of wounds and failure of those wounds to heal. Given the severity of the problem, there is an undeniable and urgent need for new antibiotics active against MDR Gram-negative pathogens and capable of modulating bacterial biofilm formation and maintenance To address the need for the discovery of novel antibacterial agents for topical application and effective against MDR Gram-negative bacteria, including their biofilms, we propose to design and synthesize novel cyclic lipopeptides based on fusaricidin/LI-F natural products. Our recent breakthrough finding have shown that that the increase in overall hydrophobicity and net positive charge of these cyclic lipopeptides improved their activity against Gram-negative bacteria. The improvement in potency is particularly evident in the activity against bacterial biofilms, as the lead peptide 3 showed promising in vitro and in vivo activities against P. aeruginosa and A. baumannii biofilms. Importantly, structural changes resulting in more hydrophobic and positively charged analogues did not lead to increased nonspecific toxicity. Within this proposal, our overall goal is to further modify cyclic lipopeptide 3 to optimize its antibacterial/antibiofilm activity and to minimize nonspecific toxicity. Within the R21 phase we will utilize combinatorial chemistry in conjunction with screening assays to identify cyclic lipopeptide leads with high potency against planktonic and biofilm MDR Gram-negative bacteria and low nonspecific toxicity. In the R33 phase we will: a) develop an optimal delivery system for topical application based on gelatin hydrogels, b) determine the mode of action of these peptides, and c) assess the therapeutic potential of an optimized peptide/hydrogel formulation in a porcine wound infection model. Once completed, the proposed research will lead to a new class of antibacterial peptides for topical application that can be advanced to clinical studies. Once completed, the proposed research will lead to a new class of antibacterial peptides for topical application that can be advanced to clinical studies.