Selective agents against C. difficile infection

针对艰难梭菌感染的选择性药物

• 批准号: 8842587
• 负责人: Dallas Hughes
• 金额: $ 29.77万
• 依托单位: NOVOBIOTIC PHARMACEUTICALS, LLC
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8842587
• 关键词: Actinobacteria class; Address; Aerobic; Anaerobic Bacteria; Antibiotic Therapy; Antibiotics; Bacteria; Bacterial Genome; Biological Assay; Biological Availability; Biological Factors; Cells; Clostridium; Clostridium difficile; Colitis; Collection; Communities; Development; Diarrhea; Disease; Epidemic; Epithelial Cells; Escherichia coli; Essential Genes; Evaluation; Fractionation; Genes; Genome; Genomics; Goals; Growth; Hamsters; Healthcare; Individual; Infection; Intestines; Lead; Libraries; Maximum Tolerated Dose; Metronidazole; Modeling; Oral; Penetration; Pharmaceutical Preparations; Phase; Production; Relapse; Reproduction spores; Resistance; Resources; Site; Soil; Solid; Staphylococcus aureus; Structure; Testing; Therapeutic; Vancomycin; antimicrobial; base; cytotoxicity; design; drug candidate; experience; follow-up; genome sequencing; in vitro testing; in vivo; killings; liquid chromatography mass spectrometry; microbial; mutant; novel; pathogen; potency testing; prevent; programs; public health relevance; resistance frequency; scale up; screening; small molecule; success

DESCRIPTION (provided by applicant): The overall goal of this project is to develop a selective antibiotic against Clostridium difficile, the major agent responsible for antibiotic-induced diarrhea and colitis. The pathogen can be carried in healthy individuals, and is kept at bay by gut symbionts. Antibiotic treatment suppresses the normal flora, but spores of C. difficile survive, germinate and cause disease. Treatment with metronidazole, vancomycin, or fidaxomicin kills not only the pathogen, but also the symbionts, which may result in relapse. Ideally, one would like to have a therapeutic, which is selective against C. difficile, as it would allow the normal flora to restore in the course of treating the pathogen, preventing relapse. Based on genomic studies, bacteria share a core of ~200 genes, and in addition to those, there may be up to 100-200 essential genes specific to a given species/genus. We reasoned that the existence of a large number of specific targets presents an opportunity to discover antimicrobials acting selectively against C. difficile. The pathogen is an anaerobe, while HTS normally requires aerobic conditions. As a result, current therapeutics for treating the infection come from other programs, and are not selective. We developed an anaerobic HTS and performed a first direct screen against C. difficile. Given the historically high success rate of discovering antibiotics from natural products, we screened a library of extracts from soil bacteria. This library comes from an untapped resource, uncultured bacteria, and is rich in novel compounds. The library had been screened against S. aureus and E. coli, producing hit rates of 30% and 0.5%, respectively. We reasoned that the remaining "inactive" strains may harbor compounds active against particular species that were missed in the primary screen. A pilot screen of ~5,000 extracts resulted in a hit rate of 1.3% against C. difficile. Preliminary analysis of these extracts showed that two were selective against C. difficile when tested against a small panel of gut commensals, and contained compounds with novel masses. In the proposed project, we will follow up on these hits, and screen 50,000 additional extracts from the "inactive" library. Hits will be de-replicated by LC/MS, which will indicate the degree of novelty, and tested against representatives of the main groups of gut symbionts. Clostridium-selective compounds passing dereplication will be tested for potency, resistance frequency, cytotoxicity and penetration into intestinal epithelial cells. Compounds that are not absorbed and thus retained at the site of infection will be given priority. Structure determination will confirm novelty and provde information on the suitability of compounds for further development. Whole genome sequencing of resistant mutants will indicate the likely target. Maximum tolerated dose and bioavailability of leads will be determined in hamsters, which will inform the design of a C. difficile efficacy study The goal of Phase I is to identify two to three lead compounds with efficacy in a hamster model of C. difficile infection. This will form a solid basis for a Phase II application aimed at preclincal development towards an IND.

描述（由申请人提供）：该项目的总体目标是开发针对艰难梭菌的选择性抗生素，这是负责抗生素引起的腹泻和结肠炎的主要药物。病原体可以在健康的个体中携带，并由肠道共生体保留。抗生素治疗抑制了正常的菌群，但艰难梭菌的孢子生存，发芽并引起疾病。用甲硝唑，万古霉素或菲达素治疗的治疗不仅杀死病原体，而且还杀死可能导致复发的共生体。理想情况下，人们想拥有一种治疗性，对艰难梭菌具有选择性，就像它一样 在治疗病原体的过程中恢复正常的菌群，以防止复发。 基于基因组研究，细菌具有约200个基因的核心，除了这些基因外，还可能有多达100-200个特定于给定物种/属的基本基因。我们认为，存在大量特定靶标有一个机会，可以选择反对艰难梭菌作用的抗菌剂。病原体是厌氧菌，而HTS通常需要有氧条件。结果，当前用于治疗感染的治疗剂来自其他程序，并且不是选择性的。我们开发了厌氧HTS，并对艰难梭菌进行了第一个直接筛选。鉴于从天然产物中发现抗生素的历史上很高的成功率，我们从土壤细菌中筛选了一个提取物库。该库来自未开发的资源，未培养的细菌，并具有丰富的新颖化合物。该图书馆已经针对金黄色葡萄球菌和大肠杆菌进行筛选，分别产生了30％和0.5％的命中率。我们认为，其余的“无活性”菌株可能会在主要筛选中遗漏的特定物种具有活跃的化合物。约5,000个提取物的试点屏幕对艰难梭菌的命中率为1.3％。初步分析 这些提取物中有两种针对艰难梭菌的选择性，当对艰难梭菌进行测试时，对肠道的小面板进行了测试，并包含具有新质量的化合物。在拟议的项目中，我们将跟进这些命中，并从“无活动”中筛选50,000个摘录 图书馆。 LC/MS将删除命中，这将指示新颖性的程度，并测试 反对肠道共生体的主要群体的代表。梭状芽胞杆相选择的化合物将测试是否有能力，抗性频率，细胞毒性和渗透到肠上皮细胞中。未吸收并因此保留在感染部位的化合物将得到优先级。结构确定将确认有关化合物对进一步开发的适用性的新颖性和预示信息。抗性突变体的整个基因组测序将表明可能的靶标。最大耐受剂量和生物利用度 铅将在仓鼠中确定，这将为艰难梭菌功效研究的设计提供信息，第一阶段的目标是在艰难梭菌感染的仓鼠模型中确定具有功效的两到三种铅化合物。这将为旨在旨在朝向IND的linc骨开发的II期应用构成坚实的基础。