Epithelial MMPs in Airway Repair

描述（由申请人提供）：在许多情况下，如闭塞性细支气管炎、哮喘、囊性纤维化等，气道的累积性、进行性重塑表明正常的修复过程已经出错。为了了解破坏性疾病的致病机制，需要更好地了解正常气道修复的机制。损伤引发了一系列相互依赖但独立的反应，如上皮再生，炎症，瘢痕形成，并最终解决。在这个过程的每个阶段，所有细胞都会释放大量的细胞外蛋白酶。这些酶作用于特定底物，具有许多不同的功能，包括通过功能获得和功能丧失机制调节细胞-细胞和细胞-基质信号传导。特别地，基质金属蛋白酶（MMP）家族的成员可以激活参与细胞通讯的许多蛋白质的潜在形式，以及几种其他功能。该项目的目标是确定实际的，特定的基质金属蛋白酶的生理蛋白质底物，了解蛋白水解加工给定的蛋白质的生物学后果，并确定MMP活性的调节。基因敲除小鼠的初步数据表明，气道金属蛋白酶，特别是基质溶素（MMP 7）和epilysin（MMP 28），调节不同的，非重叠的过程中必不可少的正常修复。尽管基质溶解素是上皮再形成和中性粒细胞流入所需的，但上皮溶解素似乎在调节全身性炎症方面发挥更有限的作用。本项目的总体目标是确定这些基质金属蛋白酶在有或无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解素在气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解素作用于促进上皮再形成的底物。对于目标2，调节基质溶解素的催化活性的机制将进行评估，重点是假设的酶原的激活和活性酶的不活动是由嗜酸性粒细胞生成的氧化剂，特别是HOCI介导的位点特异性修饰控制。对于目标3，基因靶向小鼠将用于测试气道来源的癫痫溶解素通过蛋白水解加工调节炎症的想法（即，激活）潜在因素（例如，趋化因子）或辅助蛋白（例如，多配体聚糖）。这些研究将证明特定MMPs在气道修复中的重要功能。

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.