Nature inspired treatments for persistent C. difficile infections

描述（由申请方提供）：由于高毒力菌株的增加，艰难梭菌感染（CDI）变得更加难以治疗，高毒力菌株增加了感染患者的发病率和死亡率以及持续和复发的可能性。为了解决对新的抗艰难梭菌剂的迫切需求，我们探索了自然界利用好的细菌（即益生菌），包括乳杆菌属，抑制肠道病原体如C.艰难梭菌通过生产新的抗菌剂，这是优化的进化肠道的微环境。在这方面，我们探索了从罗伊氏乳杆菌中开发罗伊环素作为天然抗艰难梭菌剂的潜力。益生菌正在成为CDI的替代治疗方法。然而，关于活益生菌是否可以用于治疗严重的CDI，特别是在免疫功能低下的患者中，仍存在争议。因此，我们假设开发由益生菌产生的抗菌剂将利用其天然治疗特性之一局部杀死C。艰难梭菌在肠道，提供了一个更可靠和有效的治疗策略。将这一概念应用于我们对reutericyclin的研究表明，它具有令人印象深刻的抗微生物和治疗CDI的药理学特性。这些包括：快速杀死不生长的、产毒素的固定相C.难以辨认的;对细菌膜特异的新作用机制;窄的活性谱;缺乏对肠上皮细胞的细胞毒性;对蛋白水解的稳定性;在肠中达到高的非吸收浓度以用于杀死的能力;允许先进的化学优化的低分子量和易于合成。重要的是，目前处方的抗生素万古霉素和甲硝唑不能杀死产毒素的稳定期细胞，它们只能杀死活跃生长的C。很难我们相信，开发益生菌衍生的罗伊环素衍生物以治疗CDI的这一提议是高度创新的，并且将通过三个迭代目标来实现：（i）合成扩大的罗伊环素类似物组以优化抗艰难梭菌活性并增加对膜靶位点的亲和力;（二）先导开发和表征，涉及化合物通过三个阶段的测试逐步进展，包括抗菌评估，药代动力学测试、毒理学和体内功效实验。符合测试选择标准的化合物将进入下一阶段，从而获得具有有效体内功效和优异安全性的主要候选物;（iii）作用模式研究，以探索靶向梭菌膜的基本抗菌作用。该项目的长期目标是开发益生菌衍生的reutericyclin的优化的先导类似物，其在膜靶点处表现出新的作用模式，并具有表征的抗生素特性，这将使其作为治疗CDI的候选物进入高级临床前研究。

DESCRIPTION (provided by applicant): Clostridium difficile infections (CDI) have become more difficult to treat due to the rise of hypervirulent strains that have increased morbidity as well as mortality and the likelihood of persistence and relapse in infected patients. To address the dire need for new anti-difficile agents, we explored the premise that nature utilizes good bacteria (i.e. probiotics), including Lactobacillus spp., to suppress gut pathogens such as C. difficile by producing novel antimicrobials, which were optimized by evolution to the microenvironment of the gut. In this regard, we explored the potential for developing reutericyclin from Lactobacillus reuteri as a natural anti- difficile agent. Probiotics are emerging as alternate treatments for CDI. However, there is ongoing debate on whether live probiotics may be used treat severe CDI, especially in immunocompromised patients. We therefore hypothesize that developing the antimicrobial produced by the probiotic specie would harness one of its natural therapeutic properties for localized killing of C. difficile in the gut, providing a more reliable and efficacious treatment strategy. Application of this concept to our studies on reutericyclin revealed that it has impressive antimicrobial and pharmacological properties for treating CDI. These include: rapid killing of nongrowing, toxin- producing stationary phase C. difficile; a novel mechanism of action specific to the bacterial membrane; a narrow spectrum of activity; lack of cytotoxicity against gut epithelia; stability to proteolysis; ability to achieve high non- absorbed concentrations in gut for killing; a low molecular weight and ease of synthesis that will allow advanced chemical optimization. Importantly, the killing of toxin-producing stationary phase cells is not shown by currently prescribed antibiotics vancomycin and metronidazole, which only kill actively growing C. difficile. We believe that this proposal for developing probiotic-derived reutericylcin derivatives to treat CDI is highly innovative and will be achieved through three iterative aims: (i) Synthesis of an expanded sets of reutericyclin analogs to optimize anti-difficile activity and increase affinity for the membrane target site ; (ii) Lead development and characterization involving the stepwise progression of compounds through three stages of tests that include antimicrobial assessment, pharmacokinetic testing, toxicologic and in vivo efficacy experiments. Compounds meeting the selection criteria of the tests will move onto the next stage such that a lead candidate is obtained with potent in vivo efficacy and excellent safety profile; (iii) Mode of action studies to explore the fundamental antibacterial effects of targeting the clostridial membrane. The long-term goal of this project is to develop optimized lead analogs of probiotic derived reutericyclin that exhibit novel modes of action at the membrane target and have characterized antibiotic properties that would allow their progression into advanced preclinical studies as candidates for treating CDI.