Bile Acids and Clostridium scindens Inhibit C. difficile: Role of Secreted Antibacterial Compounds

胆汁酸和梭菌抑制艰难梭菌：分泌的抗菌化合物的作用

• 批准号: 9233344
• 负责人: PHILLIP B HYLEMON
• 金额: --
• 依托单位: VA VETERANS ADMINISTRATION HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9233344
• 关键词: Age; Amino Acids; Animal Model; Anti-Bacterial Agents; Antibiotic Therapy; Antibiotics; Bacteria; Bile Acids; Binding; Cells; Cessation of life; Chenodeoxycholic Acid; Cholic Acids; Clinical; Clostridium; Clostridium difficile; Colitis; Colon; Communities; Cyclic Amino Acids; Cyclic Peptides; Deoxycholic Acid; Diarrhea; Doctor of Philosophy; Elderly; Enzymes; Gastrointestinal tract structure; General Population; Genes; Goals; Grant; Growth; Health; Hospitals; Human; In Vitro; Individual; Infection; Laboratories; Lithocholic Acid; Metronidazole; Nature; Patients; Peptide Antibiotics; Periodicity; Population; Publishing; Relapse; Reporting; Reproduction spores; Resistance; Risk; Role; Secondary to; Structure; Technology; Vancomycin; alpha Toxin; cost; fecal transplantation; gut microbiome; gut microbiota; high risk; in vivo; killings; member; pathogenic bacteria; patient population; prevent; relapse patients; transcriptome sequencing

ABSTRACT PI- Phillip B. Hylemon, Ph.D. Title: “Bile Acids and Clostridium scindens Inhibit C. difficile: Role of Secreted Antibacterial Compounds” Clostridium difficile, the cause of antibiotic associated diarrhea and colitis, is a growing health threat for patients taking broad spectrum antibiotics. It has been estimated that C. difficile may be responsible for almost a half a million infections per year and 29,000 deaths in the US at an annual cost of $4.8 billion dollars. Patients on broad-spectrum antibiotics markedly decrease the levels of protective gut microbiota and allows proliferation of C. difficile normally found in low levels in some individuals. Patients treated with antibiotics, especially in hospitals, are also at risk for colonization by C. difficile spores, which germinate in the GI tract (stimulated by specific bile acids) producing vegetative cells that secrete toxins A and B causing diarrhea and colitis. Patients with antibiotics associated diarrhea and/or colitis are routinely treated with either metronidazole or vancomycin to kill C. difficile vegetative cells colonizing the colon; however, up to 30% all patients successfully treated with these antibiotics will relapse following cessation of antibiotic therapy. Fecal transplants, using gut microbiota from healthy donors, have been highly successful in treating relapsing patients. Recent studies, published in Nature, were undertaken to determine which members of the gut microbiota are responsible for resistance to C. difficile infection. It was reported that Clostridium scindens, a human gut bacterium that converts the primary bile acids, cholic acid (CA) and chenodeoxycholic acid (CDCA) to secondary bile acids, deoxycholic acid (DCA) and lithocholic acid (LCA), respectively, is strongly associated with inhibition of C. difficile infections in both animal models and in human patients. This past year, our laboratory made two important discoveries that may explain how C. difficile is able to colonize the human GI tract, when patients are treated with antibiotics, and how C. scindens inhibits the growth and colonization by C. difficile. Aim 1: Confirm the structure and characterize the mechanism of action of a cyclic 6 amino acid antibiotic peptide secreted by C. difficile that inhibits the growth of C. scindens and other human gut bacteria. Subaim 1a. Determine if clinical strains of C. difficile secrete the same compound. Aim 2: Purify, characterize, and determine the structure of a CA inducible antibacterial compound(s) secreted by C. scindens ATCC 35704 and VPI 12708 that inhibits the growth of C. difficile and other pathogenic bacteria in vitro. Subaim 2a. Determine the spectrum of different bacteria inhibited by this compound(s). Subaim 2b. Identify the bile acid inducible genes encoding the enzymes(s) involved in the synthesis of this antibacterial compound using RNAseq technology. Subaim 2c. Characterize the mechanism of inhibition of C. difficile growth by this compound(s). Aim 3: Screen multiple strains of C. scindens for antibacterial compounds that inhibit C. difficile. Subaim 3a. Develop a “cocktail” of C. scindens strains producing different antibacterial compounds to use in the treatment of patients with infections. Subaim 3b. Develop strains of C. scindens resistant to the 6 amino acid cyclic antibiotic peptide secreted by C. difficile. Long Term Objective: Find safe and effective ways to prevent and treat C. difficile infections using different strains of C. scindens and inhibitory compounds secreted by C. scindens. Determine how bile acids and antibacterial compounds, secreted by different species of the genus Clostridium, regulate the gut microbiome community structure.

摘要 PI-菲利普B。Hylemon博士 标题：“胆汁酸和梭菌抑制C。艰难梭菌：分泌型抗菌素的作用 化合物” 艰难梭菌是抗生素相关腹泻和结肠炎的病因，其感染率正在不断上升 对服用广谱抗生素患者的健康威胁。据估计，C.艰难 在美国，每年可能造成近50万人感染，29,000人死亡， 每年花费48亿美元。使用广谱抗生素的患者 保护肠道微生物群的水平，并允许C.艰难梭菌通常存在于低 在某些人的水平。接受抗生素治疗的患者，特别是在医院， C.定殖风险艰难梭菌孢子，其在胃肠道中萌发（由特定的 胆汁酸）产生营养细胞，分泌毒素A和B，引起腹泻和结肠炎。 抗生素相关性腹泻和/或结肠炎患者常规治疗为 甲硝唑或万古霉素杀灭C.艰难的营养细胞定植结肠;然而， 所有成功使用这些抗生素治疗的患者中，有30%在停止使用抗生素后会复发。 抗生素治疗利用健康捐赠者的肠道微生物群进行粪便移植， 成功治疗复发的病人。最近发表在《自然》杂志上的研究表明， 确定肠道微生物群的哪些成员负责抵抗C。艰难 感染据报道，梭状芽孢杆菌，一种人类肠道细菌， 初级胆汁酸、胆酸（CA）和鹅去氧胆酸（CDCA）转化为次级胆汁酸， 脱氧胆酸（DCA）和石胆酸（LCA）分别与 抑制C.在动物模型和人类患者中的艰难梭菌感染。去年，我们 实验室有两个重要的发现可以解释C. difficile能够在 人类胃肠道，当病人用抗生素治疗，以及如何C。植物生长抑制 和C.很难目的1：确定结构并表征 由C.艰难梭菌抑制生长的 C.细菌和其他人类肠道细菌。Subaim 1a.确定临床菌株是否为C.艰难 分泌相同的化合物。目的2：纯化、表征和确定CA的结构 由C.对ATCC 35704和VPI 12708进行了筛选， 抑制C.艰难梭菌和其他致病菌的体外培养。Subaim 2a.确定 该化合物抑制的不同细菌的谱。Subaim 2b.鉴别胆汁酸 编码参与该抗菌化合物合成的酶的诱导基因 使用RNAseq技术。Subaim 2c.并对其抑制C.艰难 通过该化合物的生长。目的3：筛选多株C.抗菌闪烁剂 抑制C.很难Subaim 3a.开发C的“鸡尾酒”。菌属菌株 产生不同的抗菌化合物用于治疗感染患者。 Subaim 3b.开发C.菌株。对6个氨基酸的环状抗生素肽具有抗性的细菌 C.很难长期目标：寻找安全有效的预防和治疗方法 C.艰难梭菌感染使用不同菌株的C.分泌的抑制性化合物 C.你好确定不同物种分泌的胆汁酸和抗菌化合物 Clostridium属，调节肠道微生物群落结构。