Mechanisms of myeloperoxidase and Nox4 interactions in abdominal aortic aneurysm

项目摘要 腹主动脉瘤（AAA）疾病是发病率和死亡率的常见原因。 每年大约进行25，000次AAA修复，AAA导致13，000多人死亡 每年在美国。AAA形成的潜在机制尚不清楚， 阻碍了有效的医学治疗方法的发展。在这里，我们专注于新的假设， 髓过氧化物酶（MPO），一种主要在中性粒细胞（PMN）中表达的白细胞酶， H2 O2促进氧化应激和炎症反应，在AAA的发病机制中起关键作用。我们 提供了新的初步数据，表明MPO在AAA形成期间在主动脉中累积， Nox 4基因缺失，Nox 4是一种独特的高产量H2 O2酶促生产者， 平滑肌细胞（SMC），阻断MPO摄取并预防AAA。我们进一步建议，PMN AAA中的激活/MPO累积受前列腺素D2（PGD 2）和烟酸（GPR 109 A）调节 受体，并且“重新利用”靶向这些炎症细胞受体的可用药物是一种有效的治疗方法。 有吸引力的AAA治疗策略。我们的中心假设是MPO与Nox 4合作， 促进AAA中有害的氧化应激，其可通过以下方式进行治疗性调节 靶向PGD 2受体和GPR 109 A。提出了三个目标来检验我们的中心假设： 目的1，我们将测试的假设，Nox 4与MPO合作，在AAA的发病机制，使用 转基因小鼠和一种新开发的质谱分析法， 确定腹主动脉瘤形成过程中主动脉MPO摄取和活性是否依赖于Nox 4。 我们还将确定在造血细胞中过表达人MPO是否会增强AAA， 形成，如果是这样，它是否可以通过SMC Nox 4缺失来克服。在目标2中，我们将测试 PGD 2受体促进PMN/MPO募集和MPO介导AAA形成的假说 使用基因修饰的小鼠，其中DP 1或DP 2的一个或两个等位基因已经缺失， 以及药理学DP受体激动剂和拮抗剂。在目标3中，我们将检验假设 GPR 109 A通过GPR 109 A敲除调控PMN活化和MPO介导的AAA形成 小鼠结合药理学方法。目标2和3的一个特别重点是， 对AAA患者可行且有效的有前景的治疗策略。这 该应用解决了该领域的两个重大差距：i）识别AAA的基本机制 ii）使用这些知识来推进AAA患者的医学治疗。

PROJECT SUMMARY Abdominal aortic aneurysm (AAA) disease is a frequent cause of morbidity and mortality. Roughly 25,000 AAA repairs are performed each year, and AAAs account for over 13,000 deaths annually in the United States. The underlying mechanisms of AAA formation are unknown, which has hampered development of effective medical therapies. Here, we focus on the novel hypothesis that myeloperoxidase (MPO), a leukocyte enzyme expressed primarily in neutrophils (PMNs) that utilizes H2O2 to promote oxidative stress and inflammation, plays a key role in the pathogenesis of AAA. We provide novel preliminary data showing that MPO accrues in the aorta during AAA formation, and that genetic deletion of Nox4, a unique high-output enzymatic producer of H2O2 that is highly expressed in smooth muscle cells (SMCs), blocks MPO uptake and prevents AAA. We further propose that PMN activation/MPO accrual in AAA are regulated by prostaglandin D2 (PGD2) and nicotinic acid (GPR109A) receptors, and that “repurposing” available drugs that target these inflammatory cell receptors is an attractive therapeutic strategy in AAA. Our central hypothesis is that MPO cooperates with Nox4 to promote deleterious oxidative stress in AAA, which can be therapeutically modulated by targeting PGD2 receptors and GPR109A. Three aims are proposed to test our central hypothesis: in Aim1, we will test the hypothesis that Nox4 cooperates with MPO in the pathogenesis of AAA using genetically modified mice and a newly developed mass spectrometry assay that will enable us to determine whether aortic MPO uptake and activity are dependent upon Nox4 during AAA formation. We will also determine whether overexpression of human MPO in hematopoietic cells enhances AAA formation, and if so, whether it can be overcome by SMC Nox4 deletion. In Aim 2, we will test the hypothesis that PGD2 receptors promote PMN/MPO recruitment and MPO-mediated AAA formation using genetically modified mice in which one or both alleles of DP1 or DP2 have been deleted, coupled with and pharmacologic DP receptor agonists and antagonists. In Aim 3, we will test the hypothesis that GPR109A modulates PMN activation and MPO-mediated AAA formation using GPR109A knockout mice coupled with pharmacologic approaches. A particular emphasis of Aims 2 and 3 is to identify promising therapeutic strategies that are both feasible and effective for patients with AAA. This application addresses two significant gaps in the field: i) identifying fundamental mechanisms of AAA formation and ii) using this knowledge to advance medical treatment for patients with AAA.