Proteases in Airway Remodeling and Host Defense

在慢性炎症的呼吸道中，上皮细胞表层成分改变，上皮下基质增厚，粘膜下腺增大，血管数量和管径改变。这些转化导致哮喘和慢性支气管炎的呼吸道阻塞和高分泌。该项目的总体目标是检验细胞外蛋白水解酶是慢性呼吸道炎症重塑的决定因素的假设。拟议的研究包括体外探索这些蛋白酶的分子行为和靶点，以及在体内研究选定的蛋白酶及其靶点在基因工程小鼠中的作用，包括那些感染了肺支原体以产生慢性呼吸道重塑模型的小鼠。目标1是确定I型上皮膜锚定丝氨酸蛋白酶的作用，重点是 与前列腺素相关的呼吸道表达的酶。我们已经鉴定并鉴定了这一新发现的表面锚定多肽酶家族的新成员，我们假设它们调节气道液的盐和水含量，预防慢性呼吸道感染，并维持对慢性炎症的上皮重塑反应。目的2确定肥大细胞及其蛋白水解酶在防御慢性呼吸道感染中的作用。来自小鼠体内研究的几条证据表明，肥大细胞及其蛋白酶在感染常规肺炎的先天免疫反应中发挥关键作用。 急性腹膜炎和肺炎中的细菌。在这一目的中，我们建议测试肥大细胞对支原体的免疫反应的假设，支原体是一种独特的病原体，在具有免疫能力的宿主动物中产生终身的、呼吸道的、特异性的感染，并伴随着呼吸道结构的深刻变化。目的3是建立人类类胰蛋白酶基因变异的机制和意义。在小鼠和人类的研究中，肥大细胞类胰蛋白酶与过敏性炎症环境下的呼吸道重塑有关。我们发现类胰蛋白酶基因的遗传发生了惊人的变化，包括大约五分之一的人类完全缺乏α-类胰蛋白酶。此外，我们发现，缺乏催化不活跃的α-类胰蛋白酶的人继承了额外的β-类胰酶，而β-类胰酶是活跃的。因此，观察到的后果 变化可能是深远的。这项研究旨在探索类胰蛋白酶基因变异的机制，并研究这种变异在与气道重塑相关的疾病中的作用。总体而言，为该项目提出的研究确定了重塑的机制，这些机制可能建议以前未探索的预防或逆转伴随慢性呼吸道炎症的解剖学变化的策略。

In chronically inflamed airway, the surface layer of epithelial cells changes composition, subepithelial matrix thickens, submucosal glands enlarge, and blood vessels change in number and caliber. These transformations contribute to airway obstruction and hypersecretion in asthma and chronic bronchitis. This project's overall goal is to test the hypothesis that extracellular proteases are determinants of remodeling in chronic airway inflammation. The proposed studies include in vitro explorations of the molecular behavior and targets of these proteases and in vivo studies of selected proteases and their targets in genetically engineered mice, including those infected with Mycoplasma pulmonis to generate a model of chronic airway remodeling. Aim 1 is to determine roles of epithelial type I membrane-anchored serine proteases, focusing on airway-expressed enzymes related to prostasin. We have identified and characterized novel members of this newly recognized family of surface-anchored peptidases, which we hypothesize to regulate salt and water content of airway fluids, protect against chronic airway infection, and maintain epithelial remodeling responses to chronic inflammation. Aim 2 is to determine roles of mast cells and their proteases in defense against chromic airway infection. Several lines of evidence from in vivo studies in mice suggest that mast cells and their proteases play critical roles in innate immune responses to infections with conventional bacteria in acute peritonitis and pneumonia. In this aim we propose to test the hypothesis that mast cells contribute to immune responses to mycoplasma, a distinct class of pathogen that produces lifelong, airway, specific infection in immunocompetent host animals accompanied by profound alterations in airway architecture. Aim 3 is to establish mechanisms and significance of variations in human tryptase genotype. In mouse and human studies, mast cell tryptases are implicated in airway remodeling in settings of allergic inflammation. We discovered striking variations in inheritance of tryptase genes, including complete absence of alpha-tryptase in about one-fifth of humans. Further, we find that humans lacking alpha-tryptases, which are catalytically inactive, inherit extra beta-tryptases, which are active. Thus, consequences of the observed variation may be profound. The studies in this Aim explore mechanisms of variation in tryptase genotype and examine roles of such variation in diseases associated with airway remodeling. Overall, the studies proposed for this project identify mechanisms of remodeling that may suggest previously unexplored strategies to prevent or reverse anatomical changes accompanying chronic airway inflammation.