Design of pH-responsive Peptide Assembly for Acid-activatable Antimicrobial Therapy

非技术概述细菌可以感染身体的所有部位，包括pH值低于中性的部位，如尿路、口腔、呼吸道上皮、皮肤和其他软组织。虽然许多抗菌剂在中性pH时具有最佳的杀菌活性，但不寻常的酸性pH会削弱药物的抑菌和杀菌活性，并促进细菌耐药性。抗菌肽(AMPs)因其广谱的抗菌活性和较少的细菌耐药性而成为传统抗生素的替代方案，以解决全球性的传染病问题。虽然AMPs被认为是传统抗生素的有前途的替代品，但它们的广泛使用和转化为临床应用受到几个内在限制的阻碍，包括它们对蛋白酶的敏感性和对宿主细胞的中到重度毒性。人们普遍认为，需要新的设计和工程策略来克服传统AMPS用于靶向抗菌治疗的内在局限性。PI的团队最近开发了一种自组装抗菌纳米纤维(SAANs)的技术平台，以绕过传统抗生素和AMP的缺点。SAAN是多结构域肽(MDP)的超分子组装，可以程序化地自组装成纳米结构的细丝。在杀灭广谱抗生素耐药细菌的同时，SAANs在提高稳定性、精确控制AMP载量、最小的细胞毒性和极大改善血液相容性方面具有传统单链AMP无法比拟的主要优势。最近，PI的小组提出了基本的设计原则，以pH响应的MDP作为分子构建块来开发一种新型的可酸激活的SAAN。长期目标是将SAANs作为稳定的系统纳米载体应用于AMP的靶向递送。本建议的研究目标是扩大含有对pH敏感的非天然氨基酸的SAAN家族，以进一步调节材料的稳定性和活性，并开发更有效的pH依赖的多组分SAAN，具有协同抗菌作用，在不影响健康组织和细胞的情况下在其首选的酸性环境中杀灭细菌。在德克萨斯大学阿灵顿分校，这是一所为拉美裔服务的机构，PI为STEM领域增加多样性的教育做出了贡献，特别是鼓励成绩不佳的代表不足的学生参与研究，以及她的其他外联和教育努力。技术概述NSF项目的重点是用非天然氨基酸合成和自组装具有pH响应性的多肽，这些多肽在弱酸性范围内显示出触发的抗菌活性。该项目是由我们最近发现的可酸激活的自组装抗菌纳米纤维(AA-SAANs)推动的，这种纳米纤维是通过对pH响应的多结构域多肽(MDP)的自组装产生的。MDP在生理条件下组装成纳米纤维，处于非活性状态。在局部pH下降的酸性感染部位，AA-SAANs被触发分解和释放活化的MDP，与细菌细胞膜相互作用，杀死细菌。在这项提案中，我们将验证和推进基本的设计原则，通过使用MDP和扩展化学来开发更有效的AA-SAAN。该方案的研究目标是：1)利用含有非天然离子氨基酸的新型pH响应型MDP构建AA-SAANs；2)制备和评价具有协同抗菌活性的多组分AA-SAANs；3)评价这些材料的体外pH依赖生物活性。这些努力将为控制AA-SAANs的结构和抗菌活性的基本分子和超分子化学提供重要的见解。此外，这一战略对于合理设计和合成具有内置pH响应特性的功能材料具有极大的变革性，以探索各种复杂的生物过程，其中pH梯度起着重要作用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical SummaryBacteria can infect all body parts, including those with pH values below neutral, such as the urinary tract, oral cavity, respiratory epithelia, skin, and other soft tissues. While many antimicrobial agents have optimal bactericidal activity at a neutral pH, the unusual acidic pH can impair the bacteriostatic and bactericidal activities of pharmaceutical drugs and promote bacterial resistance. Antimicrobial peptides (AMPs) have emerged as an alternative solution to conventional antibiotics to address the global problem of infectious diseases due to their broad-spectrum antimicrobial activity and less tendency for bacteria to develop resistance. Although AMPs are considered promising alternatives to conventional antibiotics, their widespread use and translation into clinical application is hampered by several intrinsic limitations, including their susceptibility to proteases and moderate to severe toxicity towards host cells. It is generally believed that new design and engineering strategy is needed to overcome the intrinsic limitation of traditional AMPs for targeted antimicrobial therapy. The PI’s group recently developed a technology platform of self-assembling antimicrobial nanofibers (SAANs) to circumvent the shortcomings of both traditional antibiotics and AMPs. SAANs are supramolecular assemblies of multidomain peptides (MDPs) that can undergo programmed self-assembly into nanostructured filaments. While killing broad-spectrum antibiotic-resistant bacteria, SAANs offer key advantages over traditional single chain AMPs in terms of improved stability, precisely controlled AMP loading capacity, minimal cytotoxicity and greatly improved hemocompatibility. More recently, the PI’s group advance the fundamental design principles to develop a novel acid-activatable SAANs using pH-responsive MDPs as the molecular building block. The long-term goal is to apply SAANs as stable systemic nanocarriers for targeted AMP delivery. The research objectives of the present proposal are to expand the family of SAANs containing pH-responsive non-natural amino acids to further modulate materials stability and activity, and to develop more potent pH-dependent multicomponent SAANs with synergistic antimicrobial effect to eradicate bacteria at their preferred acidic environment without affecting healthy tissues and cells. At the University of Texas at Arlington which is a Hispanic-serving institution, the PI contributes to education of increased diversity in STEM fields, particularly encouraging research participation from underrepresented students with weakly performing academic record along with her other outreach and education efforts. Technical SummaryThe NSF project is focused on the synthesis and self-assembly of pH-responsive peptides with non-natural amino acids that show triggered antimicrobial activity in the weakly acidic pH range. The project is driven by our recent discovery of Acid-Activatable Self-Assembled Antimicrobial Nanofibers (AA-SAANs), which is generated through the self-assembly of pH-responsive multidomain peptides (MDPs). The MDPs are assembled into nanofibers at the physiological condition and being inactive. At the acidic infection site where the local pH decreases, AA-SAANs are triggered to dissemble and release the activated MDPs to interact with the bacterial cell membrane and kill bacteria. In this proposal we will validate and advance the fundamental design principle by using MDPs with expanded chemistry to develop more potent AA-SAANs. The research objectives of this proposal are: 1) Establish AA-SAANs using new pH-responsive MDPs containing non-natural ionic amino acids; 2) Fabrication and evaluation of multicomponent AA-SAANs with synergistic antimicrobial activity; 3) Evaluate the pH-dependent biological activity of these materials in vitro. These efforts will provide critical insight into the fundamental molecular and supramolecular chemistry that govern the structure and antimicrobial activity of AA-SAANs. Further, this strategy is highly transformative for the rational design and synthesis of functional materials with built-in pH-responsive properties to probe various complex biological processes in which pH gradient plays an important role.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.