Gut Microbiota, Trimethylamine N-Oxide, and Endothelial Dysfunction in Middle-Aged Adults

项目摘要 在过去的十年中，人们越来越认识到肠道微生物群与 许多心血管表型。其中最突出的是肠道微生物代谢之间的联系 来自膳食来源的三甲胺（TMA）部分（胆碱、磷脂酰胆碱、L-肉毒碱等）和CVD。肠道 微生物通过cutC TMA裂解酶的作用代谢膳食胆碱以释放TMA。TMA被吸收， 被肝黄素单加氧酶（FMO 3）氧化形成三甲胺N-氧化物（TMAO）。TMAO已经 在动物模型中与动脉粥样硬化血栓形成疾病有因果关系，并在队列研究中预测CVD风险。的 这项R21建议的总体目标是：1）确定可行性，并对影响进行概念验证 补充酒石酸氢胆碱对中年人循环TMAO和内皮依赖性舒张功能的影响 以便将来进行更大，更全面的试验; 2）建立我们测量肠道的熟练程度 微生物群组成和功能;以及3）获得用于产生效应量的初步数据。为此，继 我们将24名中年成人（45-65岁）随机分为4周的酒石酸胆碱组， (1000 mg/d）或安慰剂。将向受试者提供其所有食物，胆碱和TMA部分摄入量维持在 在研究期间，从我们的代谢厨房摄入美国饮食的膳食水平，以避免潜在的混淆 通过个体之间TMA部分的习惯性饮食摄入的差异。TMAO的测量 通过UPLC-MS/MS进行浓缩，使用高分辨率超声进行流动介导的扩张，以及肠道微生物群 将分别使用16 S rRNA焦磷酸测序和靶向qt-PCR进行组成/功能分析， 每4周治疗期后。这种创新的综合和翻译生理学研究将是 由一个知名私家侦探进行和调查团队，拥有丰富的经验和良好的成功记录 进行针对心脏代谢功能障碍的干预研究。这些研究具有重要的翻译意义。 潜力，因为它们可能会将啮齿动物的基础科学发现推向人类，并为人类提供新的机制见解 在人类中进行的观察性研究，通过确定饮食胆碱对内皮功能的影响， 与宿主肠道微生物群的相互作用。反过来，肠道微生物群可能是治疗的关键目标， 有助于维持健康的内皮或治疗内皮功能障碍。重要的是，我们的研究 还将提供对肠道微生物群的深入了解，作为个体间变异性增加的重要来源， TMAO和血流介导的血管扩张对饮食胆碱摄入的反应。因此，后者可以提供以下理由： 个性化的营养或其他干预措施，针对肠道微生物群作为我们所吃食物之间的界面 和宿主生理学（即，内皮功能）。

Project Summary In the past decade, there has been increasing appreciation for an association between the gut microbiota and numerous cardiovascular phenotypes. One of the most prominent has been the link between gut microbial metabolism of trimethylamine (TMA) moieties from dietary sources (choline, phosphatidylcholine, L-carnitine, etc.) and CVD. Gut microbes metabolize dietary choline to release TMA via the action of cutC TMA lyase. TMA is absorbed and then oxidized by hepatic flavin monooxygenases (FMO3) to form trimethylamine N-oxide (TMAO). TMAO has been causally linked to atherothrombotic disease in animal models and is predictive of CVD risk in cohort studies. The overall objectives of this R21 proposal are to: 1) determine the feasibility and establish proof-of-concept for the effects of choline bitartrate supplementation on circulating TMAO and endothelial-dependent dilation in middle-aged adults in order to conduct a larger, more comprehensive trial in the future; 2) establish our proficiency in measuring gut microbiota composition and function; and 3) obtain preliminary data for effect size generation. To this end, following a two-week lead-in diet, we will randomize twenty-four middle-aged adults (45-65 yrs) to 4-weeks of choline bitartrate (1000 mg/d) or placebo. Subjects will be provided all of their food with choline and TMA-moiety intake maintained at meal levels intake of the US diet for the duration of the study from our metabolic kitchen to avoid potential confounding through differences in habitual dietary intake of TMA moieties between individuals. Measurements of TMAO concentration by UPLC-MS/MS, flow-mediated dilation using high resolution ultrasound, and gut microbiota composition/function using 16S rRNA pyrosequencing and targeted qt-PCR, respectively will be made before and following each 4-week treatment period. This innovative integrative and translational physiological study will be conducted by an established P.I. and investigative team with extensive experience and a strong record of success performing intervention studies targeting cardiometabolic dysfunction. These studies have significant translational potential as they may advance basic science findings in rodents to humans and provide novel mechanistic insight into observational studies in humans by establishing the effect of dietary choline on endothelial function through its interaction with the host intestinal microbiota. In turn, the gut microbiota may be a key target for therapies that may contribute to the maintenance of a healthy endothelium or treatment of endothelial dysfunction. Importantly, our study also will provide insight into the gut microbiota as important source of inter-individual variability in the increase in TMAO and flow-mediated dilation responses to dietary choline intake. As such, the latter may provide rationale for individualizing nutritional or other interventions that target the gut microbiota as an interface between the food we eat and host physiology (i.e., endothelial function).