Mechanisms of alteration of GI physiology by gut microbes

肠道微生物改变胃肠道生理学的机制

• 批准号: 9547844
• 负责人: Purna C Kashyap
• 金额: $ 35.78万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9547844
• 关键词: Affect; Aromatic-L-Amino-Acid Decarboxylases; Bacteria; Bicarbonates; Biological Response Modifier Therapy; Clostridium; Complex; Constipation; Data; Decarboxylation; Development; Diet; Disease; Ecosystem; Electrolytes; Engineered Probiotics; Enzymes; Epithelial; Epithelium; Exhibits; Fluids and Secretions; Gastrointestinal Physiology; Gastrointestinal tract structure; Genes; Genetic Engineering; Gnotobiotic; Goals; Health; Human; In Vitro; Intestinal Secretions; Intestines; Irritable Bowel Syndrome; Knockout Mice; Laboratory Research; Ligands; Mediating; Microbe; Modeling; Molecular; Mucous Membrane; Mus; Organ; Organoids; Pathway interactions; Physiological; Physiology; Play; Pre-Clinical Model; Probiotics; Production; Role; Ruminococcus; Serotonergic System; Serotonin; Signal Transduction; Testing; Therapeutic; Tissues; Tryptamines; Tryptophan; bacterial metabolism; base; commensal bacteria; gastrointestinal; gastrointestinal function; gut bacteria; gut microbes; gut microbiota; humanized mouse; in vivo; microbial; microbiota; novel; pathogenic bacteria; pre-clinical; receptor; self organization; self-renewal

ABSTRACT The overall goal of our laboratory's research is to determine the mechanisms by which gut microbiota and their products alter gastrointestinal (GI) tract luminal physiology and to develop microbiota-based therapeutic manipulations to correct altered physiology in diseases like irritable bowel syndrome (IBS) associated with alterations in gut microbiota. Our preliminary studies have identified the gene tryptophan decarboxylase which converts dietary tryptophan to tryptamine in common human gut commensal bacteria like Ruminococcus gnavus and Clostridium sporogenes. Furthermore our preliminary data show that tryptamine increases short circuit current (representing ionic flux; surrogate for secretion) across the colonic epithelium in vitro in Ussing chamber studies and this effect can be inhibited by serotonin receptor4 (5HT4R) antagonists and is absent in 5HT4R knock out mice. Interestingly genetically engineered bacteria with the gene tryptophan decarboxylase produce tryptamine in vivo in gnotobiotic mice and accelerate whole gut transit, when diet is supplemented with tryptophan. Our overall hypothesis is that dietary tryptophan driven production of bacterial tryptamine increases 5HT4R-mediated intestinal secretion modulating GI function in health and disease. In order to determine the mechanism of action of tryptamine we will first determine if the effect of exogenous tryptamine on intestinal secretion is dependent on 5HT4R and identify specific downstream pathways responsible for secretion. We will then investigate the effect of dietary tryptophan on bacteria produced tryptamine and 5HT4R mediated intestinal secretion and whole gut transit as well as its application in a preclinical model of constipation. The results from this study will potentially contribute to the development of novel engineered probiotics capable of producing a bioactive metabolite such as tryptamine to correct the altered physiology such as constipation in diseases like IBS.

摘要 我们实验室研究的总体目标是 确定肠道微生物区系和它们的 产品改变胃肠道(GI)腔内生理和 开发以微生物群为基础的治疗方法 纠正肠易激综合征(IBS)等相关疾病生理学改变的手法 肠道微生物区系的变化。我们的初步研究已经确定了色氨酸脱羧酶基因 在常见的人类肠道共生细菌中将饮食中的色氨酸转化为色胺，如瘤胃球菌 Gnavus和产孢子梭菌。此外，我们的初步数据显示，色胺在短期内增加 电路电流(代表离子通量；替代分泌物)通过体外培养的结肠上皮 小室研究发现，这种作用可以被5-羟色胺受体4(5HT4R)拮抗剂抑制，而在 5HT4R基因敲除小鼠。有趣的是，带有色氨酸脱羧酶基因的基因工程菌 在GnotoBiotic小鼠体内产生色胺，并加速整个肠道的转运 色氨酸。我们的总体假设是，饮食中的色氨酸驱动细菌色胺的产生增加 5HT4R介导的肠道分泌在健康和疾病中调节胃肠道功能。为了确定 色胺的作用机制我们首先要确定外源性色胺对肠道的影响 分泌依赖于5HT4R，并确定负责分泌的特定下游途径。我们会 然后研究了膳食色氨酸对产色胺细菌和5HT4R介导的细菌的影响 肠道分泌物和全肠道运输及其在便秘临床前模型中的应用。这个 这项研究的结果可能有助于开发能够 产生一种生物活性代谢物，如色胺，以纠正改变的生理，如便秘 像IBS这样的疾病。