抗菌肽压力下全耐药鲍曼不动杆菌的系统应激及相关抗菌通路探讨

Acinetobacter baumannii is becoming resistant to colistin and tigecycline (i.e. PDR Ab) thus pose great threats to hospitalized patients. As an important part of the innate immunity, some antimicrobial peptides (AMPs) show powerful effects on many multi-drug resistant clinical isolates while resistance to AMPs is rare, which make them potential candidates as novel antibiotics. Research ongoing about AMPs is mainly focused on resource mining or structure-function relationship while neglect the fact that as peptides, AMPs has its own weaknesses such as instability in vivo, hemolytic activity, or uncontrollable immune-regulatory effects, etc. when administered directly. Besides, the antimicrobial mechanisms of AMPs, especially the mechanisms on drug-resistant pathogens, are still to be uncovered. We have screened out Cathelicidin-BF and Tachyplesin-III, two potential AMPs that are effective on PDR Ab in our previous studies. Here we plan to study the global responses of PDR Ab under AMP stresses by comparative transcriptomics and quantitative proteomics, then investigate the key signaling pathways or targets that are responsible for the antimicrobial mechanisms through CRISPR-on/off, by which we may uncover the unique strategies AMPs used which are different from the antibiotics available. The results of this study are not only important to the theory of AMPs’ antimicrobial mechanisms, but also may offer theory and experimental clues for novel stable, safe and effective antibiotics that are hard to cause drug resistance.

鲍曼不动杆菌开始对多粘菌素、替加环素耐药（即PDR Ab），对临床造成了严重威胁。作为天然免疫成分的某些抗菌肽对多种临床耐药菌具有出色杀伤作用且不易诱导耐药性，是一类抗微生物药领域极具开发潜力的分子。之前的研究主要聚焦于抗菌肽分子发掘、构效关系，但抗菌肽直接作为药物使用有其天然缺陷，如体内稳定性差、溶血或不可控免疫调节的毒副作用等；另外其抗菌机制，尤其抗耐药菌的系统研究有待进一步深入。申请者在前期研究中筛选出两个对PDR Ab有效的抗菌肽。本课题拟通过比较转录组和iTRAQ定量蛋白质组分析抗菌肽压力下PDR Ab的系统应激反应，并进一步通过CRISPR-on/off技术研究相关应激反应中的关键抗菌通路，揭示抗菌肽可能不同于现有抗生素的有效抗耐药菌机制。本研究成果不仅对阐明抗菌肽抗菌机制具有重要的理论意义，更有可能进一步为基于抗菌肽作用机制的稳定、安全、不易耐药的新药开发提供理论与实验依据。

临床致病菌开始对多粘菌素和替加环素耐受，对临床造成了严重威胁。作为天然免疫成分的某些抗菌肽对多种临床耐药菌具有出色杀伤作用且不易诱导耐药性，是一类抗微生物药领域极具开发潜力的分子。之前的研究主要聚焦于抗菌肽分子发掘和构效关系，但抗菌肽直接作为药物使用具有天然缺陷，如体内稳定性差/溶血或不可控免疫调节的毒副作用等；另外其抗菌机制，尤其抗耐药菌的系统研究有待进一步深入。通过体外抑菌实验/小鼠肺炎模型/转录组学及蛋白质组学分析，我们筛选出两个活性较好的多肽。其中cathelicidin-BF可能靶向细菌的能量代谢等途径直接杀菌，体内先于细菌感染使用可有效募集巨噬细胞和中性粒细胞形成免疫屏障从而使机体表现出无差别的攻击保护；tachyplesin-III可通过靶向各种细菌胞内保守的不饱和脂肪酸合成酶FabG导致质膜不稳定，从而表现出伴随细菌死亡出现的细胞膜破裂，为进一步针对此类不同于传统抗生素的新型抗菌药物开发提供了新靶点。