Development of antimicrobial peptide therapeutics for multidrug-resistant systemic bacterial infection

目前发现和开发新型抗生素的困难正在成为一大卫生保健危机。随着抗菌素耐药性的出现，这种情况更加具有挑战性。拟议项目的基本假设是，在硅胶中设计α-螺旋多肽在时间效率和成本降低方面为鉴定新型抗菌化合物提供了极好的可能性。这项提议的长期目标是利用结构指导原则设计新型的硅胶抗菌肽(AMP)，这种抗菌肽将有效地对抗由革兰氏阴性菌和革兰氏阳性菌引起的系统性细菌感染。我们的目标是设计出具有合适的效力、选择性、稳定性和适当的PK/PD特性的短α-螺旋AMP。我们将用三个具体的目标来验证我们的中心假设：目的1)在细菌特异性AMP的电子设计中，包括基于经典的3.613α-螺旋核心(鲍林-科里-布兰森α-螺旋)的手动设计，该核心包含12个氨基酸残基，具有可变电荷和疏水性平衡，然后使用AlphaFold2进行分子动力学建模和结构预测。目的2)确定所设计的多肽的活性、毒性、稳定性及其作用机制。目的3)在梅隆乳杆菌蜡蛾模型和小鼠全身感染模型中评价多肽的体内药效。此外，我们还将使用聚乳酸-乙醇酸(PLGA)和/或壳聚糖纳米载体，评估选定的、设计的AMP的纳米制剂，以供未来在小鼠体内潜在使用。在完成提议的目标后，将确定新的候选AMP，这将有助于缓解当前的抗菌危机。

Current difficulties in discovering and developing novel antibiotics is becoming a major health care crisis. This situation is even more challenging with the emergence of antimicrobial resistance. The underlying hypothesis of the proposed project is that the design of α-helical peptides in silico offers excellent possibilities for identifying novel antimicrobial compounds with respect to time efficiency and cost reduction. The long-term goal of this proposal is to utilize structure-guided principles to design novel antimicrobial peptides (AMPs) in silico that will be effective against systemic bacterial infection caused by both Gram-negative bacteria and Gram-positive bacteria. We aim to engineer short α-helical AMPs with suitable potency, selectivity, stability, and appropriate PK/PD properties. We will test our central hypothesis with three specific aims: Aim 1) In silico design of bacteria-specific AMPs that includes manual design based on a classic 3.613 α-helix core (Pauling–Corey–Branson α-helix) containing 12 amino acid residues with varying charge and hydrophobicity balance followed by molecular dynamics modeling and structure predictions using AlphaFold2. Aim 2) Determine the activity, toxicity, stability, and mechanism of action of designed peptides. Aim 3) In vivo efficacy evaluation of peptides in a Galleria mellonella wax moth model and subsequently in a systemic mouse infection model. In addition, we will also evaluate nanoparticle formulations of selected, designed AMPs for potential future in vivo use in mice using a poly(lactic-co-glycolic acid) (PLGA) and/or chitosan nanocarrier. Upon completion of the proposed objectives, novel candidate AMPs will be identified that will help mitigate the current antimicrobial crisis.