Elucidating the Role of Endothelial NAD Metabolism in Atherosclerosis

阐明内皮 NAD 代谢在动脉粥样硬化中的作用

• 批准号: 10655649
• 负责人: Ioana Soaita
• 金额: $ 1.3万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2023-11-03
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10655649
• 关键词: Acceleration; Adenine Nucleotides; Adhesions; Age; Aging; Aorta; Area; Arterial Fatty Streak; Atherosclerosis; Blood Vessels; Bypass; Carbon Isotopes; Cardiovascular system; Cause of Death; Cells; Clinical; Consumption; Coupled; Deacetylase; Deacetylation; Development; Endothelial Cells; Endothelium; Enzymes; Equilibrium; Event; Family; Functional disorder; Histology; Homeostasis; Human; Hyperlipidemia; Impairment; Inflammation; Intervention; Label; Lead; Lipids; Liver; Mediating; Metabolic; Metabolism; Methods; Modeling; Mus; NOS3 gene; Niacinamide; Nicotinamide adenine dinucleotide; Nitric Oxide; Oils; Oral; Oral Administration; Oxidative Stress; Pathogenesis; Pathologic; Pathology; Pathway interactions; Phenotype; Prevalence; Process; Production; Public Health; Reaction; Reporting; Risk Factors; Role; SIRT1 gene; Sirtuins; Stains; Supplementation; Testing; Text; Therapeutic; Tissues; United States; Vasodilation; Work; aged; atherogenesis; atherosclerosis risk; career; experimental study; gain of function; human disease; improved; in vitro activity; loss of function; metabolic abnormality assessment; modifiable risk; mouse model; nicotinamide phosphoribosyltransferase; nicotinamide-beta-riboside; novel therapeutic intervention; nucleotide metabolism; overexpression; prevent; stable isotope; stress reduction

Project Summary Atherosclerosis remains a leading cause of death in the United States, even in the context of aggressive clinical and public health efforts to lower risk factors such as hyperlipidemia. Thus, there is a significant need for better mechanistic understanding of atherosclerosis pathogenesis in order to develop novel therapeutic strategies downstream of circulating risk factors. Atherosclerosis pathogenesis begins in the endothelial layer of the arterial wall: endothelial cell dysfunction (ECD) and EC inflammation precede atherosclerotic plaque formation and are associated with adverse cardiovascular events. Both ECD and EC inflammation increase with age, and age is a major non-modifiable risk factor for atherosclerosis. Importantly, activation of sirtuin (SIRT) family of nicotinamide adenine dinucleotide (NAD+) - dependent deacetylases, particularly SIRT1, has been reported to slow a variety of age-associated phenotypes. In particular, our lab and others have shown that levels of endothelial NAD+ decrease with age, and that endothelial-specific overexpression of SIRT1 is sufficient to slow ECD and progression of atherosclerosis. Furthermore, oral administration of NAD+ precursors in aged mice increases aortic SIRT1 expression and activity, and reduces ECD, suggesting that increasing NAD+ availability can promote SIRT1 activity in aged ECs. Loss of NAD+ balance thus appears to be central to atherogenesis, but little is known about how ECs maintain NAD homeostasis. Quantitative flux analysis of NAD+ precursors in live mice has recently uncovered that liver-derived nicotinamide (NAM) is the main circulating NAD+ precursor that reaches tissues. This suggests that the enzyme NAM phosphoribosyltransferase (NAMPT), which catalyzes the first and rate-limiting step in NAD+ synthesis from NAM, is critical for producing endothelial NAD+ and maintaining the activity of NAD+ - dependent enzymes. Thus, I hypothesize that endothelial NAMPT is cell-autonomously required to produce NAD+ and maintain endothelial SIRT1 activity, and that endothelial NAMPT overexpression will protect against progression of atherosclerosis. To test this hypothesis, we have generated endothelial-specific gain-of-function (GOF) and loss-of-function (LOF) NAMPT mouse models. In Aim 1, I will use cultured primary arterial ECs and stable isotope carbon tracing coupled with quantitative flux analysis to calculate rates of NAMPT NAD+ production and SIRT1 NAD+ consumption. I will also determine if NAMPT activity is required for SIRT1 deacetylation activity, and if NAMPT activation is sufficient to maintain SIRT1 activity upon oxidative stress. In Aim 2, I will test if NAMPT GOF or oral NAD+ supplementation is sufficient to slow progression of atherosclerosis, and if NAMPT LOF accelerates atherosclerosis. Ultimately, this work will improve understanding of EC NAD+ metabolism and its role in maintaining SIRT1 activity, and inform if NAMPT activation and/or NAD+ replenishment could be a therapeutic avenue for reducing the burden of atherosclerosis independently of circulating risk factors such as hyperlipidemia.

项目摘要 动脉粥样硬化仍然是美国死亡的主要原因，即使在积极的临床上也是 和公共卫生为降低危险因素（例如高脂血症）的努力。因此，非常需要更好 对动脉粥样硬化发病机理的机械理解，以发展新型的治疗策略 循环危险因素的下游。动脉粥样硬化发病机理始于动脉的内皮层 墙：内皮细胞功能障碍（ECD）和EC炎症先于动脉粥样硬化斑块形成，并且是 与不良心血管事件有关。 ECD和EC炎症随着年龄的增长而增加，年龄是 动脉粥样硬化的主要不可修改的危险因素。重要的是，激活烟酰胺的Sirtuin（SIRT）家族 报道 与年龄相关的表型。特别是，我们的实验室和其他实验室表明内皮NAD+的水平 随着年龄的增长而降低，SIRT1的内皮特异性过表达足以减慢ECD和 动脉粥样硬化的进展。此外，老年小鼠的口服NAD+前体增加 主动脉SIRT1表达和活动，并减少ECD，表明增加NAD+可用性可以促进 SIRT1活性在老年ECS中。因此，NAD+平衡的丧失似乎是动脉粥样硬化的核心，但鲜为人知 关于EC如何维持NAD的稳态。活小鼠中NAD+前体的定量通量分析已有 最近发现的是，肝脏衍生的烟酰胺（NAM）是达到的主要循环NAD+前体 组织。这表明酶NAM NAM磷酸贝糖基转移酶（NAMPT），它催化了第一个和 NAM NAD+合成中的速率限制步骤对于产生内皮NAD+至关重要 NAD+依赖性酶的活性。因此，我假设内皮nampt是细胞自主的 需要产生NAD+并维持内皮SIRT1活动，而内皮nampt 过表达将防止动脉粥样硬化的进展。为了检验这一假设，我们有 产生的内皮特异性功能获得（GOF）和功能丧失（LOF）NAMPT小鼠模型。目标 1，我将使用培养的初级动脉EC和稳定的同位素碳追踪和定量通量分析 计算NANP NAD+生产和SIRT1 NAD+消耗的速率。我还将确定是否 SIRT1脱乙酰化活性需要活性，如果NAMPT激活足以维持SIRT1活性 氧化应激。在AIM 2中，我将测试NAMPT GOF或口服NAD+补充是否足以缓慢 动脉粥样硬化的进展，如果NAMPT LOF加速了动脉粥样硬化。最终，这项工作将有所改善 了解EC NAD+代谢及其在维持SIRT1活动中的作用，并告知NAMPT是否激活 和/或NAD+补充可能是减轻动脉粥样硬化负担的治疗途径 独立于循环危险因素（例如高脂血症）。