MATRILYSIN IN LUNG EPITHELIAL CELL INJURY AND REPAIR

我们观察到肺泡巨噬细胞表达基质金属蛋白酶。 肺泡损伤后的上皮细胞与组织化 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。苦参素不存在于 正常肺的呼吸道上皮细胞。肺手术后，母溶素 用免疫组织化学和原位杂交法检测到 II型细胞穿过裸露的肺泡壁。Matrilysin阳性 细胞主要分布在受损或被破坏的基底区域。 膜，并放置在含有纤维连接蛋白的基质上。Matrilysin是 通常是一种“上皮细胞来源的”基质金属蛋白酶，但其他基质金属蛋白酶是 已知由某些上皮细胞产生，即I型胶原酶， 人肺不产生基质分解素-1和明胶酶B 呼吸道上皮。大鼠和人肺泡的体外实验研究 上皮细胞表现出很强的基质溶素mRNA和 蛋白质表达。基质溶素的表达也被显著诱导。 囊性纤维化和重症哮喘中的呼吸道上皮细胞 提示在损伤介导的反应中起作用。支持这一点 概念，我们发现通过人类呼吸道的迁移增强了基质溶素的表达 (气管)上皮细胞在组织修复的体外模型中。在这样的情况下 外植体，机械伤后，免疫反应阳性的基质溶素 在移行的气管上皮内和下面均可见 细胞。基于这些观察，我们假设母体溶血素 II型肺泡细胞的表达伴随着严重的肺泡损伤，以及 推测这种基质金属蛋白酶的蛋白分解活性是需要的 促进细胞迁移和修复。为了解决这一假设，我们 提出以下具体目标：1)我们将审查 肺泡上皮细胞基质溶素在牙槽骨修复中的表达 在实验性急性肺损伤后；2)我们将确定影响 基质溶素对人和啮齿动物肺泡上皮细胞行为的影响 3)我们将定义基质溶素的表达是如何在 人和啮齿动物肺泡上皮细胞。要实现这些目标 目标，我们将利用不同的细胞生物学和分子生物学 包括研究母溶素缺陷与野生型的方法 老鼠。我们将确定迁移是否需要母体溶血素 II型肺泡细胞，细胞是否与临时基质接触 蛋白质刺激基质溶素的表达，细胞内 基质溶素在肺泡上皮细胞中的诱导机制

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.