Epithelial MMPs in Airway Repair

描述(由申请人提供)：在许多情况下，如闭塞性毛细支气管炎、哮喘、囊性纤维化等，呼吸道的累积性、进行性重构表明正常的修复过程已经出错。要了解破坏性疾病的发病机制，需要更好地了解正常呼吸道修复的机制。损伤引发了一系列相互依赖但又相互独立的程序化反应，如再上皮化、炎症、疤痕形成，最终消退。在这个过程的每个阶段，所有细胞都会释放一些胞外蛋白水解酶。这些酶作用于特定的底物，具有多种不同的功能，包括通过获得和失去功能的机制来调节细胞-细胞和细胞-基质信号。尤其是，基质金属蛋白酶家族的成员可以激活一些参与细胞通讯的蛋白质的潜伏形式，以及其他几种功能。该项目的目标是确定特定MMPs的实际、生理蛋白质底物，了解对给定蛋白质进行蛋白质分解的生物学后果，并确定MMPs活性的调节。对基因敲除小鼠的初步数据表明，呼吸道金属蛋白酶，特别是基质溶素(MMP7)和外切酶(MMP28)，调节着正常修复所必需的不同的、不重叠的过程。虽然基质溶素是再上皮化和中性粒细胞流入所必需的，但附着素似乎在调节全身性炎症方面起到了更有限的作用。这个项目的总体目标是确定这些MMPs在有或没有潜在损伤或感染的移植气管和肺中的功能。对于目标1，将使用体内和基于细胞的模型来评估基质溶素在呼吸道修复和损伤中的表达模式、来源和功能。这些研究的目的是确定基质溶素作用于何种底物以促进再上皮化。对于目标2，将评估调节Matrilysin的催化活性的机制，重点是假设酶原的激活和活性酶的失活是由中性粒细胞产生的氧化剂，特别是hocI介导的位点特异性修饰控制的。对于目标3，基因靶向的小鼠将被用来测试呼吸道来源的Eepysin通过潜在因子(例如趋化因子)或附属蛋白(例如Syndecans)的蛋白分解处理(即激活)来调节炎症的想法。这些研究将证明特定的MMPs在呼吸道修复中的基本功能。

DESCRIPTION (provided by applicant): The accumulative, progressive remodeling of airways seen in many conditions, such as bronchiolitis obliterans, asthma, cystic fibrosis, and more, indicates that normal repair processes have gone awry. To understand the pathogenic mechanisms of destructive diseases, the mechanisms of normal airway repair need to be better understood. Injury sets off a programmed series of interdependent yet separate responses, such as re-epithelialization, inflammation, scarring, and eventually resolution. During each stage in this process, a number of extracellular proteinases are released by all cells. Acting on specific substrates, these enzymes serve numerous and diverse functions, including regulating cell-cell and cell-matrix signaling by both gain and loss-of-function mechanisms. In particular, members of the matrix metalloproteinase (MMP) family can activate the latent forms of a number of proteins involved in cellular communication, among several other functions. The goal of this project is to identify actual, physiologic protein substrates of specific MMPs, to understand the biological consequence of proteolytically processing a given protein, and to determine the regulation of MMP activity. Preliminary data with knock-out mice indicate that airway metalloproteinases, specifically, matrilysin (MMP7) and epilysin (MMP28), regulate distinct, non-overlapping processes essential for normal repair. Whereas matrilysin is required for re-epithelialization and neutrophil influx, epilysin seems to serve a more confined role to regulating generalized inflammation. The overall goals of this project are to determine the function of these MMPs in transplanted trachea and lung with and without underlying injury or infection. For Aim 1, both in vivo and cell-based models will be used to assess the expression patterns, source, and function of matrilysin in airway repair and damage. The goal of these studies is to identify the substrate upon which matrilysin acts to facilitate re-epithelialization. For Aim 2, the mechanisms regulating matrilysin's catalytic activity will be assessed, with a focus on the hypothesis that activation of the zymogen and inaction of the active enzyme are controlled by site-specific modifications mediated by neutrophil-generated oxidants, specifically HOCI. For Aim 3, gene targeted mice will be used to test the idea that airway-derived epilysin regulates inflammation by proteolytic processing (i.e., activation) of a latent factor (e.g., a chemokine) or accessory protein (e.g., syndecans). These studies will demonstrate essential functions served by specific MMPs in airway repair.