NEP and susceptibility to hypoxic pulmonary hypertension

NEP 与缺氧性肺动脉高压的易感性

• 批准号: 6728398
• 负责人: EDWARD CHARLES DEMPSEY
• 金额: $ 22.42万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6728398
• 关键词: angiogenesis; apoptosis; biological signal transduction; bombesin like peptide; cell growth regulation; cell proliferation; cytoprotection; enzyme activity; enzyme induction /repression; enzyme mechanism; fibroblasts; focal adhesion kinase; genetically modified animals; guanine nucleotide binding protein; isozymes; laboratory mouse; neprilysin; neuropeptide receptor; perfusion; protein kinase C; pulmonary artery; pulmonary hypertension; respiratory hypoxia; tissue /cell culture; vascular smooth muscle

DESCRIPTION (provided by applicant): In large animal models of hypoxic pulmonary hypertension (PHTN) that closely parallel human disease, the earliest pulmonary artery (PA) smooth muscle cell (SMC) proliferative changes occur at the medial/adventitial border. Migration of SMC and/or myofibroblasts to more distal vessels is also a prominent feature. A murine model that adequately mimics these hypoxia-induced changes has not been described. Neutral endopeptidase (NEP; or neprilysin) is an important cell surface peptidase that degrades vasoactive neuropeptides (like the bombesin-like peptides [BLPs]), that may promote vascular remodeling. NEP has also been shown to directly engage in intracellular signaling by novel peptidase independent mechanisms. Finally, NEP has recently been associated with decreased inflammation, carcinogenesis and growth. These observations support the possibility that in the lung (in contrast to the heart and systemic vasculature) NEP could exert a protective effect on susceptibility to hypoxic PHTN. We now have strong preliminary evidence to support this concept. We have found that targeted deletion of NEP in mice predisposes to exaggerated hypoxic PHTN. The resulting structural changes are more substantial than in previously described mouse models and for the first time demonstrate proximal changes at the medial/adventitial border. Recruitment of dedifferentiated SMC or myofibroblasts into the distal circulation is also a major feature. This unique pattern of vascular remodeling, together with intriguing observations in the literature, suggest key roles for BLPs, BLP receptors, selected isozymes of protein kinase C (PKC alpha, delta, and epsilon), Rho, and focal adhesion kinase (FAK). The following hypotheses will be tested: #1) NEP protects the lung vasculature from the development of hypoxic PHTN and limits vascular remodeling by suppressing the proliferation, migration, and contraction of PA SMC. #2) Selected neuropeptides (initial focus: BLPs) are largely responsible for the exaggerated pulmonary vascular remodeling observed in the chronically hypoxic NEP knockout (KO) mouse. Hypoxia- induced upregulation of BLPs and BLP receptors contributes to the increased medial/adventitial changes. #3) Upregulation of BLP post-receptor signaling intermediates (PKC a, delta , and epsilon, Rho, and FAK) contributes to the exaggerated remodeling. NEP inhibits these signaling intermediates as well as proliferation and migratory responses of PA SMC by peptidase dependent and independent mechanisms. Integrated experiments will be performed in single and double KO mice, perfused lungs, isolated pulmonary arteries and PA SMC. These studies will draw on a unique mouse model of hypoxia-induced pulmonary vascular remodeling to increase our understanding of the mechanisms that control susceptibility to hypoxic-PHTN and could identify new therapeutic targets to limit or reverse this important clinical problem.

描述（由申请人提供）： 在密切平行人类疾病的低氧肺动脉高压（PHTN）的大动物模型中，最早的肺动脉（PA）平滑肌细胞（SMC）增殖发生了变化。 SMC和/或肌纤维细胞向更远端血管的迁移也是一个突出的特征。尚未描述一种充分模拟这些缺氧引起的变化的鼠模型。中性内肽酶（NEP；或Neprilysin）是一种重要的细胞表面肽酶，可降解血管活性神经肽（例如bombesin样肽[BLPS]），可能促进血管重塑。 NEP还显示出通过新型肽酶独立机制直接参与细胞内信号传导。最后，NEP最近与炎症，癌变和生长减少有关。这些观察结果支持了肺中的可能性（与 心脏和全身性脉管系统）NEP可能对低氧PHTN的易感性产生保护作用。 现在，我们有强大的初步证据来支持这一概念。 我们发现，小鼠中NEP的靶向缺失易于夸大缺氧PHTN。所产生的结构变化比以前描述的小鼠模型和用于 第一次在内侧/外在边界展示近端变化。招募 远端循环中的去分化SMC或成肌细胞也是主要特征。这种血管重塑的独特模式以及文献中有趣的观察结果表明，BLP，BLP受体，蛋白激酶C（PKC Alpha，Delta和Epsilon）的选定同工酶，RHO和局灶性粘附激酶（FAK）的关键作用。 将检验以下假设：＃1）NEP通过抑制PA SMC的增殖，迁移和收缩来保护肺脉管系统免受低氧PHTN的发展，并限制血管重塑。 ＃2）选定的神经肽（初始焦点：BLP）在很大程度上是在慢性低氧NEP敲除（KO）中观察到的夸大肺血管重塑的原因。 老鼠。低氧诱导的BLP和BLP受体上调有助于增加 内侧/外向变化。 ＃3）上调BLP后受体信号传导中间体（PKC A， Delta和Epsilon，Rho和Fak）有助于夸张的重塑。 NEP抑制这些 信号传导中间体以及肽酶对PA SMC的增殖和迁移反应 依赖和独立的机制。集成实验将在单一和 双KO小鼠，灌注肺，孤立的肺动脉和PA SMC。这些研究将利用缺氧引起的肺血管重塑的独特小鼠模型 为了增加我们对控制低氧易感性的机制的理解，并可以识别出新的治疗靶标，以限制或扭转这一重要的临床问题。