Proteases in Airway Remodeling and Host Defense

在慢性炎症的气道中，上皮细胞的表层改变成分，上皮下基质增厚，粘膜下腺体增大，血管的数量和口径改变。这些转化导致哮喘和慢性支气管炎的气道阻塞和分泌过多。本项目的总体目标是检验细胞外蛋白酶是慢性气道炎症重塑的决定因素这一假设。拟议的研究包括这些蛋白酶的分子行为和靶标的体外探索，以及在基因工程小鼠中选择的蛋白酶及其靶标的体内研究，包括感染肺支原体以产生慢性气道重塑模型的小鼠。目的1是确定上皮I型膜锚定丝氨酸蛋白酶的作用，重点是 与前列腺素相关的气道表达酶。我们已经确定并表征了这个新认识的表面锚定肽酶家族的新成员，我们假设其调节气道液的盐和水含量，防止慢性气道感染，并维持上皮对慢性炎症的重塑反应。目的2：探讨肥大细胞及其蛋白酶在气道炎症防御中的作用。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对常规免疫球蛋白的感染的先天免疫应答中起关键作用。 急性腹膜炎和肺炎中的细菌。在这个目标中，我们建议测试的假设，肥大细胞有助于免疫反应支原体，一类独特的病原体，产生终身的，气道，特异性感染的免疫功能正常的宿主动物伴随着深刻的改变，气道结构。目的3：探讨类胰蛋白酶基因型变异的机制及意义。在小鼠和人类研究中，肥大细胞胰蛋白酶与过敏性炎症环境中的气道重塑有关。我们发现了类胰蛋白酶基因遗传的惊人变异，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，人类缺乏α-类胰蛋白酶，这是催化失活，继承额外的β-类胰蛋白酶，这是活跃的。因此，观察到的结果 变化可能是深刻的。本研究旨在探讨类胰蛋白酶基因型变异的机制，并研究这种变异在气道重塑相关疾病中的作用。总体而言，本项目提出的研究确定了重塑的机制，这可能表明以前未探索的策略，以防止或逆转伴随慢性气道炎症的解剖学变化。

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.