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.

抽象的 PI- Phillip B. Hylemon 博士 标题：“胆汁酸和梭菌抑制艰难梭菌：分泌抗菌剂的作用 化合物” 艰难梭菌是抗生素相关性腹泻和结肠炎的病因，是一种日益增长的细菌 服用广谱抗生素的患者的健康威胁。据估计，艰难梭菌 美国每年可能造成近 50 万人感染和 29,000 人死亡 每年花费48亿美元。服用广谱抗生素的患者明显减少 保护性肠道微生物群的水平，并允许通常在低水平环境中发现的艰难梭菌增殖 某些人的水平。接受抗生素治疗的患者，尤其是在医院接受治疗的患者，也处于危险之中。 艰难梭菌孢子定植的风险，这些孢子在胃肠道中发芽（受到特定刺激） 胆汁酸）产生营养细胞，分泌毒素 A 和 B，引起腹泻和结肠炎。 患有抗生素相关腹泻和/或结肠炎的患者通常接受以下任一治疗 甲硝唑或万古霉素杀死结肠中的艰难梭菌营养细胞；然而，向上 30% 成功使用这些抗生素治疗的患者在停止治疗后会复发 抗生素治疗。使用健康捐赠者的肠道微生物群进行粪便移植已得到高度认可 成功治疗复发患者。最近发表在《自然》杂志上的研究旨在 确定肠道微生物群的哪些成员对艰难梭菌有抵抗力 感染。据报道，Clostridium scindens 是一种人类肠道细菌，可将 初级胆汁酸、胆酸（CA）和鹅去氧胆酸（CDCA）至次级胆汁酸， 脱氧胆酸 (DCA) 和石胆酸 (LCA) 分别与 在动物模型和人类患者中抑制艰难梭菌感染。过去的一年里，我们的 实验室取得了两项重要发现，可以解释艰难梭菌如何能够在 人类胃肠道，当患者接受抗生素治疗时，以及 C. scindens 如何抑制生长 和艰难梭菌的定殖。目标 1：确认结构并表征其机制 艰难梭菌分泌的环状 6 氨基酸抗生素肽的作用，可抑制艰难梭菌的生长 C. scincens 和其他人类肠道细菌。苏拜姆 1a.确定艰难梭菌的临床菌株是否 分泌相同的化合物。目标 2：纯化、表征并确定 CA 的结构 由 C. scindens ATCC 35704 和 VPI 12708 分泌的诱导型抗菌化合物 在体外抑制艰难梭菌和其他致病菌的生长。苏拜姆 2a.确定 该化合物抑制不同细菌的谱。苏拜姆 2b.鉴定胆汁酸 编码参与该抗菌化合物合成的酶的诱导基因 使用RNAseq技术。苏拜姆 2c.描述艰难梭菌的抑制机制 该化合物的生长。目标 3：筛选多种 C. scindens 菌株的抗菌能力 抑制艰难梭菌的化合物。苏拜姆 3a。开发 C. scindens 菌株的“鸡尾酒” 生产不同的抗菌化合物用于治疗感染患者。 苏拜姆 3b.开发对 6 氨基酸环状抗生素肽具有抗性的 C. scindens 菌株 由艰难梭菌分泌。长期目标：寻找安全有效的预防和治疗方法 使用不同菌株的艰难梭菌和其分泌的抑制性化合物进行艰难梭菌感染 C. scindens。确定不同物种如何分泌胆汁酸和抗菌化合物 梭菌属的一种，调节肠道微生物群落结构。