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 PiPhillip B.Hylemon，Ph.D. 标题：胆汁酸和梭状芽孢杆菌抑制艰难梭菌：分泌型抗菌剂的作用 化合物“ 艰难梭菌，抗生素相关性腹泻和结肠炎的原因，正在不断增长。 对服用广谱抗生素的患者的健康威胁。据估计，艰难梭菌 可能造成美国每年近50万人感染和2.9万人死亡 每年耗资48亿美元。使用广谱抗生素的患者显著减少 保护肠道微生物区系的水平，并允许艰难梭菌的增殖，通常在低水平 在一些个体中的水平。接受抗生素治疗的患者，特别是在医院接受治疗的患者，也在 在胃肠道中萌发的艰难梭菌孢子的定植风险(受特定刺激 胆汁酸)产生营养细胞，分泌毒素A和B，引起腹泻和结肠炎。 患有抗生素相关性腹泻和/或结肠炎的患者常规使用 甲硝唑或万古霉素杀灭艰难梭菌定植于结肠的繁殖细胞； 所有使用这些抗生素成功治疗的患者在停药后都会复发 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的比例一直很高。 在治疗复发患者方面取得成功。最近发表在《自然》杂志上的研究结果表明， 确定肠道微生物区系中哪些成员对艰难梭菌产生耐药性 感染。据报道，斯氏梭菌是一种人类肠道细菌，它能将 从初级胆汁酸、胆酸(CA)和鹅去氧胆酸(CDCA)到次级胆汁酸， 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。在过去的一年里，我们的 实验室有两项重要发现，可以解释艰难梭菌是如何在 人类胃肠道，当患者接受抗生素治疗时，以及丝状念珠菌如何抑制生长 艰难梭菌的定植。目的1：确定其结构并表征其作用机制 艰难梭菌分泌的环状6个氨基酸的抗菌肽对肺炎衣原体生长的抑制作用 C.scindens和其他人类肠道细菌。苏巴伊姆1a。确定艰难梭菌临床菌株 分泌相同的化合物。目标2：纯化、表征和确定CA的结构 诱导型抗菌化合物(S)由华支睾吸虫ATCC 35704和VPI 12708分泌 在体外抑制艰难梭菌和其他病原菌的生长。苏巴伊姆2a。确定 该化合物对不同细菌的抑制谱(S)。苏巴伊姆2b。鉴定胆汁酸 编码参与这种抗菌化合物合成的酶的可诱导基因(S) 使用RNAseq技术。苏巴伊姆2c.艰难梭菌抑制机制的研究 这种复合体的增长(S)。目的3：筛选多种菌种的抗菌药 抑制艰难梭菌的化合物。苏巴伊姆3a。研制一种辛德氏假丝酵母菌株的“鸡尾酒” 产生不同的抗菌化合物，用于治疗感染患者。 苏巴伊姆3b。培育对6个氨基酸环状抗菌肽具有抗药性的辛氏杆菌 由艰难梭菌分泌。长期目标：找到安全有效的预防和治疗方法 艰难梭菌感染不同品系的辛氏梭菌及其分泌的抑制化合物 C.scindens.确定不同物种分泌的胆汁酸和抗菌化合物 梭状芽胞杆菌属，调节肠道微生物群落结构。