Selected Peptidases and Pulmonary Vascular Remodeling in Chronic Obstructive Pulm

慢性缺氧性肺动脉高压（PHTN）是一个主要的临床问题，使大多数肺和心脏疾病复杂化。慢性缺氧性PHTN的发生是COPD的主要并发症，显著增加了COPD的不良预后和致死率。PHTN在COPD中的患病率相当高。COPD患者在临床病程早期出现不同程度的肺血管重塑（PHTN的关键决定因素）。在像COPD这样复杂的疾病中，重塑需要几个因素的参与，包括香烟烟雾，氧化应激，炎症以及持续或间歇性缺氧。肺动脉（PA）平滑肌细胞（SMC）在内/外膜边缘的增殖是结构变化的一个突出特征。在肺组织中含量较高的整合膜肽酶在人肺血管重构中起重要作用。我们已经表明，这些肽酶之一，脑啡肽酶（NEP），是一个重要的determinatn的易变性慢性缺氧PHTN。NEP敲除小鼠对慢性缺氧有夸大的肺动脉高压反应，与野生型对应物相比，常驻PA SMC生长增加。肺NEP表达下降，慢性缺氧的机制不明，NEP的减少是最显着的远端血管，早期PA SMC增殖和迁移发生。我们将检验总体假设：与其他肽酶相比，NEP降低易导致COPD患者肺血管重塑增加。我们提出两个目标。第一个将涉及与“正常”和患病的人肺组织中的其他肽酶相比的NEP活性水平的分析。我们将测试肽酶活性和/或表达的变化是否与COPD严重程度和肺血管重塑（以及最终的PHTN）的临床特征平行。第二项研究是使用免疫组织化学分析和激光捕获显微切割确定肺结构（血管vs气道vs肺泡壁）、位置（近端vs远端）和细胞类型（内皮、平滑肌或成纤维细胞），这些细胞类型表现出NEP相对于最接近最实质性血管重塑的其他肽酶表达的最大变化。这些研究可能有助于增加我们对控制COPD患者对慢性缺氧PHTN易感性的机制的理解，也可以确定新的治疗靶点，以限制或逆转这一重要的临床问题。 (End摘要） 公共卫生相关性： 项目叙述：肺血管中的压力升高称为肺动脉高压。由暴露于低氧水平（缺氧）引起的肺动脉高压是一个主要的临床问题，并且可以在许多患有肺和心脏疾病的患者中发现;当持续时，它可以导致心力衰竭。肺动脉高压是慢性阻塞性肺疾病（COPD）的主要和常见并发症。肺动脉高压的一个重要因素是血管中发生的异常结构变化。肺动脉壁中的平滑肌细胞可能响应于缺氧而异常生长，导致血管壁厚度增加和血管直径减小。细胞表面的一种蛋白质Neprilysin可能在调节肺动脉高压的易感性方面发挥重要作用。缺乏脑啡肽酶蛋白的小鼠对低氧的反应是肺动脉高压增加。从这些小鼠肺中分离的平滑肌细胞也比正常细胞生长得更快。我们计划分析不同程度COPD患者肺部的Neprilysin，并将其与其他相关蛋白质进行比较。我们将分两个具体步骤来做。第一步将涉及分析正常和患病人类肺组织中的脑啡肽酶和其他蛋白质。然后，我们将观察这些蛋白质的水平是否与疾病的严重程度和肺血管结构变化（肺动脉高压的标志物）的程度有关。第二个将是确定肺结构，位置和细胞类型，表现出最大量的蛋白质表达的变化。这些研究可能有助于增加我们对控制慢性缺氧性肺动脉高压易感性的机制的理解，也可以确定新的治疗靶点，以限制或逆转这一重要的临床问题。

DESCRIPTION (provided by applicant): Project Summary: Chronic hypoxic pulmonary hypertension (PHTN) is a major clinical problem, complicating most lung and heart disorders. The development of chronic hypoxic PHTN is a major complication of COPD, adding significantly to the poor prognosis and lethality of COPD. The prevalence of PHTN in COPD is quite large. Patients with COPD develop varying degrees of pulmonary vascular remodeling (a key determinate of PHTN) early in their clinical course. In a disorder as complex as COPD, remodeling requires the participation of several factors, including cigarette smoke, oxidant stress, inflammation, and persistent or intermittent hypoxia. Proliferation of pulmonary artery (PA) smooth muscle cells (SMCs) at the medial/adventitial border is a prominent feature of the structural change. Integral membrane peptidases, found in fairly high abundance in the lung, could play an important role in human pulmonary vascular remodeling. We have shown that one of these peptidases, Neprilysin (NEP), is an important determinatn of susceptability to chronic hypoxic PHTN. NEP null mice have an exaggerated pulmonary hypertensive response to chronic hypoxia, and resident PA SMCs have increased growth compared to their wild type counterparts. Lung NEP expression decreases in response to chronic hypoxia by unknown mechanisms; the decrease in NEP is most striking in distal vessels where early PA SMC proliferation and migration occurs. We will test the Overall Hypothesis that: Decreased NEP vs other peptidases predisposes to the development of increased pulmonary vascular remodeling in COPD. We propose two aims. The first will involve analysis of NEP activity level compared to other peptidases in `normal' and diseased human lung tissue. We will test if change in peptidase activity and/or expression parallel clinical characteristics of COPD severity and pulmonary vascular remodeling (and ultimately PHTN). The second will be to determine the lung structure (vessel vs airway vs alveolar walls), location (proximal vs distal), and cell type (endothelial, smooth muscle, or fibroblast) exhibiting the greatest changes in NEP vs other peptidase expression in closest proximity to the most substantial vascular remodeling using immunohistochemical analyses and laser capture microdissection. These studies may help increase our understanding of mechanisms that control susceptibility to chronic hypoxic PHTN in COPD and could also identify new therapeutic targets to limit or reverse this important clinical problem. (End of Abstract) PUBLIC HEALTH RELEVANCE: Project Narrative: Elevated pressure in the blood vessels in the lung is called pulmonary hypertension. Pulmonary hypertension induced by exposure to low oxygen levels (hypoxia) is a major clinical problem and can be found in many patients with lung and heart disorders; when sustained, it can lead to heart failure. Pulmonary hypertension is a major and common complication of chronic obstructive pulmonary disease (COPD). An important factor in pulmonary hypertension is the abnormal structural change that occurs in the blood vessels. Smooth muscle cells in the wall of lung arteries may grow abnormally in response to hypoxia leading to increased vessel wall thickness and a reduction in the vessel diameter. A protein on the cell surface, Neprilysin, may play an important role in regulating susceptibility to pulmonary hypertension. Mice lacking the Neprilysin protein have increased pulmonary hypertension in response to low oxygen. The smooth muscle cells isolated from these mouse lungs also grow faster than normal cells. We plan to analyze Neprilysin in the lungs of patients with varying degrees of COPD and compare it to other related proteins. We will do this in two specific steps. The first step will involve analysis of Neprilysin and the other proteins in normal and diseased human lung tissue. We will then see if the levels of these proteins change in relation to the severity of the disease and extent of pulmonary vascular structural change (a marker of pulmonary artery hypertension). The second will be to determine the lung structure, location, and cell type that exhibits the greatest amount of change in protein expression. These studies may help increase our understanding of mechanisms that control susceptibility to chronic hypoxic pulmonary hypertension and could also identify new therapeutic targets to limit or reverse this important clinical problem.