MATRILYSIN IN LUNG EPITHELIAL CELL INJURY AND REPAIR

我们观察到MMP基质溶解素在肺泡上皮细胞中的强表达， 肺泡损伤后上皮细胞与机化相关 弥漫性肺泡损伤，骨髓移植后特发性肺炎 综合征和间质性肺炎。基质溶素不存在于 正常肺的呼吸上皮。在肺部手术后，基质溶解素 用免疫组化和原位杂交方法检测了“排” II型细胞穿过裸露的肺泡壁。基质溶素阳性 细胞主要分布在受损或被毁的地下室区域， 膜，并停留在含纤连蛋白的基质上。基质溶素是 通常是“上皮细胞衍生的”MMP，但也有其它MMP， 已知由一些上皮细胞产生，即胶原酶-I， 基质溶解素-1和明胶酶B（MMP-9）不由人肺产生 呼吸上皮大鼠和人肺泡上皮细胞的体外研究 上皮细胞表现出较强的基质溶解素mRNA表达能力， 蛋白质表达基质溶解素的表达也被显著诱导， 囊性纤维化和严重哮喘中的气道上皮细胞， 表明在损伤介导的反应中起作用。支持这一 概念，我们发现通过迁移人类气道增强基质溶解素表达 在离体组织修复模型中的（气管）上皮细胞。以这样 外植体，机械创伤后，免疫反应性基质溶解素， 存在于迁移的气管上皮内和下方 细胞基于这些观察，我们假设基质溶解素 II型肺泡细胞表达伴随严重肺泡损伤， 推测需要这种MMP的蛋白水解活性来 促进细胞迁移和修复。为了解决这个问题，我们 提出以下具体目标：1）我们将研究 肺泡上皮细胞表达基质溶解素对肺泡修复的影响 实验性急性肺损伤后; 2）我们将确定 基质溶素对人和啮齿类动物肺泡上皮细胞行为的影响 体外; 3）我们将定义基质溶解素的表达是如何调节的， 人和啮齿动物肺泡上皮细胞。完成这些 目的，我们将采用不同的细胞生物学和分子生物学， 包括研究基质溶解素缺陷型与野生型 小鼠我们将确定基质溶解素是否是迁移所必需的 II型肺细胞，无论细胞是否与临时基质接触 蛋白质刺激基质溶解素表达， 肺泡上皮细胞中基质溶解素诱导的机制。

We have observed the strong expression of the MMP matrilysin by alveolar epithelial cells following alveolar injury associated with organizing diffuse alveolar damage, post-bone marrow transplant idiopathic pneumonia syndrome, and interstitial pneumonitis. Matrilysin is not found in the respiratory epithelium of normal lung. Following lung surgery, matrilysin was detected by immunohistochemistry and in situ hybridization in "row" of type II cells marching across denuded alveolar walls. Matrilysin-positive cells were found largely in areas of damaged or destroyed basement membrane and rested on a fibronectin-containing matrix. Matrilysin is frequently an "epithelial cell-derived" MMP, but other MMPs which are known to be produced by some epithelial cells, namely collagenase-I, stromelysin-1, and gelatinase B (MMP-9), were not produced by human lung respiratory epithelium. In vitro studies of both rat and human alveolar epithelial cells demonstrated strong capacity for matrilysin mRNA and protein expression. Expression of matrilysin was also markedly induced in airway epithelial cells in cystic fibrosis and severe asthma, again suggesting a function in injury-mediated responses. Supporting this concept, we found enhanced matrilysin expression by migrating human airway (tracheal) epithelial cells in an ex vivo model of tissue repair. In such explants, following mechanical wounding, immunoreactive matrilysin was present both within and underneath the migrating tracheal epithelial cells. Based upon these observations, we hypothesize that matrilysin expression by type II pneumocytes accompanies severe alveolar injury, and speculate that the proteolytic activity of this MMP is needed to facilitate cell migration and repair. To address this hypothesis, we propose the following specific aims: 1) we will examine the effect of matrilysin expression by alveolar epithelial cells on alveolar repair following experimental acute lung injury; 2) we will determine the effects of matrilysin on human and rodent alveolar epithelial cell behavior in vitro; and 3) we will define how matrilysin expression is regulated in human and rodent alveolar epithelial cells. To accomplish these objectives, we will employ diverse cell biological and molecular biologic approaches including the study of matrilysin-deficient versus wild-type mice. We will determine whether matrilysin is necessary for the migration of type II pneumocytes, whether contact of cells with provisional matrix proteins stimulates matrilysin expression, and the intracellular mechanisms of matrilysin induction in alveolar epithelial cells.