The Obese Microbiota as a Novel Regulator of Vascular Function: A Translational Approach

项目总结 血管功能障碍是肥胖和心血管疾病(CVD)之间的关键联系。最多的两个 血管功能障碍的临床相关表现是内皮功能障碍和动脉僵硬。 尽管有重点的努力，但肥胖者这些血管损伤的根本原因尚不清楚。 肠道微生物区系已成为人类生理的重要调节器。有害的变化 微生物区系的数量或组成，广义地称为生物失调，与 心血管疾病，以及最近的内皮功能障碍。然而，关于这一联系的四个基本问题 生物失调和血管功能障碍之间的关系仍未得到研究：1)什么特定的细菌变化启动了 血管功能障碍的发展？2)什么循环因子(S)，在生物失调的下游，调节肠道- 血管串扰和加速血管功能障碍的发展？3)除了内皮 功能障碍，生物失调是否也影响动脉僵硬？4)现有的动物数据是否与人类相关？ 血管功能障碍？ 目前提案的总体目标是解决这四个问题，并全面审查 肠道微生物区系和血管功能障碍之间的联系。根据我们最近的数据，我们假设 饮食诱导的肥胖导致肠道生物失调的一系列事件，其特征是 双歧杆菌，导致肠道屏障功能受损和循环中的升高 脂多糖(LPS)。一旦进入循环，内毒素就会激活血管系统上的Toll样受体4(TLR4)，并且 引起炎症信号级联反应，最终导致动脉僵硬和内皮功能障碍。 本文提出的翻译研究将使用三个创新的、互补的 方法：1)微生物区系移植；2)选择性微生物区系浓缩；3)无菌小鼠定居 人类微生物区系的样本。在目标1中，微生物区系移植将在对照小鼠(C57)中进行； 内毒素信号受损(TLR4-/-)；以及内毒素信号增强(酰氧酰水解酶基因敲除)的小鼠 小鼠，AOAH-/-)，喂养标准(SD)或西方(WD)饮食。在目标2中，特定的双歧杆菌种群 将从健康人群的微生物区系中分离出与WD减少并与血管功能障碍相关的基因 动物，培养，然后给WD喂养的小鼠检测它们的血管保护作用。在《目标3》中， 将确定瘦肉者和肥胖者肠道微生物区系与血管功能之间的关系；以及 来自这些个体的微生物区系样本将被用来在无菌小鼠的肠道中定居。总而言之， 这些研究将有助于确定肥胖相关血管功能障碍的新病因和治疗目标 具有广泛而直接的临床潜力。

PROJECT SUMMARY Vascular dysfunction represents a critical link between obesity and cardiovascular disease (CVD). The two most clinically relevant manifestations of vascular dysfunction are endothelial dysfunction and arterial stiffness. Despite focused efforts, the underlying cause of these vascular impairments in obese individuals is unclear. The gut microbiota has emerged as an important regulator of human physiology. Deleterious changes to the number or composition of the microbiota, broadly termed dysbiosis, have been implicated in the development of CVD, and more recently, to endothelial dysfunction. However, four fundamental questions regarding the link between dysbiosis and vascular dysfunction remain unstudied: 1) what specific bacterial alterations initiate the development of vascular dysfunction? 2) what circulating factor(s), downstream of dysbiosis, mediates intestinal- vascular crosstalk and hastens the development of vascular dysfunction? 3) in addition to endothelial dysfunction, does dysbiosis also mediate arterial stiffness? 4) are the existing animal data relevant to human vascular dysfunction? The overall goal of the current proposal is to address these four questions and comprehensively examine the link between the gut microbiota and vascular dysfunction. Building upon our recent data, we hypothesize a sequence of events whereby diet-induced obesity causes gut dysbiosis, characterized by reductions in Bifidobacterium, that lead to compromised intestinal barrier function and elevations in circulating lipopolysaccharide (LPS). Once in circulation, LPS activates toll-like receptor 4 (TLR4) on the vasculature, and elicits an inflammatory signaling cascade that ultimately lead to arterial stiffness and endothelial dysfunction. The translational studies proposed herein will test this hypothesis using three innovative, complementary approaches: 1) microbiota transplants 2) selective microbiota enrichment; and 3) colonization of germ free mice with human microbiota samples. In aim 1, microbiota transplants will be performed in control mice (C57); mice with impaired LPS signaling (TLR4-/-); and mice with enhanced LPS signaling (acyloxyacyl hydrolase knockout mice, AOAH-/-) fed either a standard (SD) or western (WD) diet. In aim 2, specific Bifidobacterium populations that are reduced by WD and correlate with vascular dysfunction will be isolated from the microbiota of healthy animals, cultured, then administered to WD-fed mice to examine their vascular protective effects. In aim 3, relations between the gut microbiota and vascular function will be determined in lean and obese individuals; and microbiota samples from these individuals will be used to colonize the intestines of germ free mice. Collectively, these studies will help identify a novel cause of, and therapeutic target for, obesity-related vascular dysfunction with broad and immediate clinical potential.