The contributory role of microbial metabolite in the pathogenesis of CKD-dependent vascular calcification

这项研究计划的长期目标是确定血管内皮细胞的分子机制， 钙化，以确定用于治疗慢性肾脏病（CKD）依赖性 血管钙化血管钙化与心血管疾病患者的死亡率密切相关， CKD。事实上，CKD患者中超过一半的死亡可归因于心血管疾病。我们 先前的研究表明，胆汁酸核受体FXR的激活强烈减弱CKD， 依赖性血管钙化的动物模型，虽然机制不明。最近，我们的代谢组学 方法已经确定，微生物胆汁酸代谢物脱氧胆酸（DCA）的水平是高度 与较高冠状动脉钙化（CAC）体积和较低的腰椎 CKD患者和小鼠的骨矿物质密度（BMD）。我们假设DCA产生于 革兰氏阳性菌导致CKD依赖性血管钙化。我们的假设也得到了 以下证据来自我们实验室的一系列初步结果：1）CKD增加了 循环DCA。2)FXR通过其激动剂激活优先降低DCA和DCA前体的水平， 胆酸。3)具有血管钙化的FXR敲除小鼠具有显著更高水平的DCA。4)CKD 改变肠道细菌种群，增加DCA产生细菌的水平。5)的fxr活化 使CKD引起的肠道菌群改变正常化。6)DCA而不是其他胆汁酸诱导 通过TGR 5-PKA-β-连环蛋白信号转导促进VSMC矿化。为了确定微生物的关键作用， DCA在血管钙化的发病机制中，我们提出3个具体目标：具体目标1：检查 DCA在体外诱导血管钙化的分子机制。具体目标2：A）检查 循环DCA水平和肠道细菌种群的改变是否影响CKD依赖性血管 体内钙化。B）检查肠道细菌的调节是否影响CKD依赖性血管内皮细胞。 体内钙化。具体目标3：检查TGR 5-PKA-β-连环蛋白信号传导是否有助于CKD-1。 体内依赖性血管钙化。

The long term objective of this research proposal is to determine the molecular mechanisms of vascular calcification in order to identify novel target(s) for the treatment of chronic kidney disease (CKD)-dependent vascular calcification. Vascular calcification is closely associated with cardiovascular mortality in patients with CKD. In fact, more than half of all deaths in CKD patients can be attributed to cardiovascular diseases. Our previous study revealed that activation of a bile acid nuclear receptor, FXR, strongly attenuates CKD- dependent vascular calcification in animal models though an unknown mechanism. Recently, our metabolomic approach has identified that levels of a microbial bile acid metabolite, deoxycholic acid (DCA), are highly associated with an increased risk for higher coronary artery calcification (CAC) volumes and lower lumbar bone mineral density (BMD) in human patients and mice with CKD. We hypothesized that DCA generated by gram-positive bacteria causes CKD-dependent vascular calcification. Our hypothesis is also supported by the following evidence derived from a series of preliminary results from our lab: 1) CKD increases levels of circulating DCA. 2) FXR activation by its agonists preferentially reduces levels of DCA and a precursor of DCA, cholic acid. 3) FXR knockout mice with vascular calcification have significantly higher levels of DCA. 4) CKD alters gut bacteria populations and increases levels of the DCA-producing bacteria. 5) Activation of FXR normalizes the alteration of gut bacteria populations by CKD. 6) DCA but not other bile acids induces mineralization of VSMCs through TGR5-PKA--catenin signaling. To determine the pivotal role of microbial DCA in the pathogenesis of vascular calcification, we propose 3 specific aims: Specific Aim 1: Examine the molecular mechanism by which DCA induces vascular calcification in vitro. Specific Aim 2: A) Examine whether alterations of circulating DCA levels and gut bacteria populations influence CKD-dependent vascular calcification in vivo. B) Examine whether modulation of intestinal bacteria affects CKD-dependent vascular calcification in vivo. Specific Aim 3: Examine whether TGR5-PKA--catenin signaling contributes to CKD- dependent vascular calcification in vivo.