MECHANISMS OF ALTERATION OF GASTROINTESTINAL MOTILITY BY GUT MICROBIOTA

摘要 人类肠道中藏有数以万亿计的微生物，这些微生物通过获取营养/能量而使宿主受益。 从我们饮食中其他不可消化的成分中摄取。值得注意的是，微生物和细菌之间的复杂信号 它们的人类宿主，以及由此对正常生理功能的影响，仍然知之甚少。 胃肠(GI)运动和肠道微生物区系明显相关，环境因素包括 饮食，可以改变胃肠动力和肠道微生物区系之间的关系。5-羟色胺；5-羟色胺 从肠嗜铬细胞(EC)释放的HT)作为一种重要的旁分泌信使参与 运动和感觉转导调节胃肠动力。我的初步研究强烈表明 5-羟色胺能途径作为肠道微生物区系的靶标。我的总体假设是肠道微生物区系改变了胃肠道 通过释放影响肠道的特定代谢物，包括色胺，以饮食依赖的方式运动 5-羟色胺能途径。我将使用无菌(GF)、灵知生物群(定义/简化的微生物区系)和人性化 (人类来源微生物定植的前GF)小鼠研究人类肠道微生物对小鼠的生理影响 老鼠模型中的宿主。由于GF小鼠完全缺乏微生物区系，它们可以用定义的 细菌群落，以创造独特的殖民状态。在具体目标1中，我将探讨 GF和人源化小鼠肠道5-羟色胺能途径上的微生物区系。在具体目标2中，我将确定 降低膳食多糖复杂性引起的变化对胃肠动力的不同影响 在肠道微生物区系中。最后，在具体目标3中，我将研究诸如色胺等微生物代谢物的作用 在调节5-羟色胺的生物合成和调节胃肠动力方面。我已经发展了体外(器官浴)和体内 VIVO(结肠测压)生理技术以及使用EC样细胞系进行筛选的策略 利用超高性能液体检测代谢产物对5-羟色胺合成和释放的影响 层析与质谱联用。我以前在胃肠道生理描绘方面的研究训练 调节胃肠道运动的复杂机制，以及我最近在微生物生态学方面的培训，因为它与 宿主功能，以及我在胃肠病方面的临床培训，重点是胃肠动力障碍， 让我有能力解决这些生物学上合理和临床上相关的问题。这份职业 发展奖将使我能够将我在两个截然不同的研究领域的技能结合起来， 神经胃肠病学和微生物生态学，以解决人类生物学的重要方面。我的导师之道 该团队由梅奥诊所的Gianrico Farrugia博士和斯坦福大学的Justin Sonnenburg博士组成； 两人都在各自的研究领域享誉国际，并在培训方面取得了成功的记录。 年轻的教员。吉安里科·法鲁贾博士是神经胃肠病学的国际领先者，他在 卡哈尔间质细胞在胃肠动力障碍中的作用。他的长期记录 对31名研究员的指导证明了指导的成功。索南伯格博士是一位进化论者 糖生物学家，因其在碳水化合物肠道利用方面的开创性工作而享誉国际 微生物和动物模型在了解肠道微生物相互作用方面的应用。 他们两人的专业知识对这个跨学科的项目都将是无价的。

Abstract The human gut harbors trillions of microorganisms that benefit the host by enabling harvest of nutrients/energy from otherwise indigestible components of our diet. Remarkably, the complex signaling between microbes and their human host, and the resulting impact on normal physiological functions, are still poorly understood. Gastrointestinal (GI) motility and the gut microbiota are clearly associated and environmental factors, including diet, can modify the relationship between GI motility and the gut microbiota. Serotonin (5-hydroxytryptamine; 5- HT) released from the enterochromaffin (EC) cells serves as an important paracrine messenger involved in motor and sensory transduction modulating GI motility. My preliminary studies strongly suggest the gut serotonergic pathway as a target for gut microbiota. My overall hypothesis is that gut microbiota alters GI motility in diet-dependent manner by release of specific metabolites, including tryptamine, which affect the gut serotonergic pathway. I will use germ-free (GF), gnotobiotic (defined/simplified microbiota), and humanized (ex-GF colonized by human-derived microbes) mice to address physiological effects of human gut microbes on the host in a mouse model. As GF mice completely lack microbiota they can be colonized with defined communities of bacteria to create distinct states of colonization. In specific aim 1, I will explore the effect of microbiota on the gut serotonergic pathway in GF and humanized mice. In specific aim 2, I will determine the differential effect on GI motility of decreasing the complexity of dietary polysaccharides with resulting alteration in gut microbiota. Finally, in specific aim 3, I will investigate the role of microbial metabolites such as tryptamine in modulating 5-HT biosynthesis and modulating GI motility. I have developed both ex vivo (organ bath) and in vivo (colonic manometry) physiological techniques as well as a screening strategy to use EC-like cell lines to test metabolites for their effect on synthesis and release of 5-HT using ultra performance liquid chromatography coupled with mass spectrometry. My previous research training in GI physiology delineating complex mechanisms regulating GI motility, as well as my recent training in microbial ecology as it relates to host function, along with my clinical training in Gastroenterology with a specific focus on GI motility disorders, gives me the ability to address these biologically sound and clinically relevant questions. This career development award will allow me to combine my skills in two very distinct areas of research, Neurogastroenterology and Microbial Ecology, to address important aspects of human biology. My mentorship team is comprised of Dr. Gianrico Farrugia at Mayo Clinic and Dr. Justin Sonnenburg at Stanford University; both are internationally renowned in their areas of research and have a successful track record in training young faculty. Dr. Gianrico Farrugia is an international leader in Neurogastroenterology, having made seminal contributions in elucidating roles of interstitial cells of Cajal in GI motility disorders. His long record of successful mentorship is evidenced by mentorship of 31 fellows. Dr. Sonnenburg is an evolutionary minded glycobiologist who is internationally renowned for his ground-breaking work on carbohydrate utilization by gut microbes and the application of gnotobiotic mouse models to understanding microbial interactions in the gut. Both of their expertise will be invaluable for this cross-disciplinary project.