ROLE OF ELASTOLYTIC METALLOPROTEINASES IN EMPHYSEMA

认为蛋白水解活性破坏肺弹性纤维 在肺气肿的发病机制中起关键作用， 主要是在患有慢性阻塞性肺病（COPD）的吸烟者中。 中性粒细胞和肺泡巨噬细胞已尽可能仔细检查 导致肺气肿的弹性蛋白酶活性的来源。 虽然一些 有证据表明中性粒细胞的重要作用， 指出肺泡巨噬细胞在肺气肿的发病机制中起关键作用 吸烟者：吸烟者的肺部数量大大增加（10至20倍） 巨噬细胞在吸烟者的肺部聚集的时间， 已知早期肺气肿的部位和巨噬细胞会释放多种 可以攻击细胞外基质成分的蛋白酶。 此外，我们已经证明，培养的人肺泡巨噬细胞 与弹性蛋白接触具有显著降解该基质能力 通过几乎完全依赖金属蛋白酶的机制。 然而，尽管有这些暗示性的特征， 人类巨噬细胞直接参与肺气肿的发病机制 因为人类巨噬细胞酶的证据有限， 降解弹性蛋白的能力。 最近，我们发现， 人肺泡巨噬细胞释放的主要蛋白酶，一种92-kDa 金属蛋白酶，具有明显的弹性蛋白分解活性。 这一发现 代表了中性蛋白酶的第一个明确的证明， 由人体巨噬细胞分泌的降解弹性蛋白的物质 扩展这些 初步观察，我们建议详细检查弹性蛋白溶解 92-kDa金属蛋白酶的性质，决定了这一作用， 人肺泡巨噬细胞降解弹性蛋白的能力中的酶， 寻找人肺组织中过量92-kDa酶的证据 并确定这种人体酶是否能产生 实验动物的肺气肿。 这些研究将使用：用途：（1） 确定92-kDa酶的结合亲和力的酶学技术 对于弹性蛋白，其催化参数和底物裂解位点;（2） 92-kDa酶的特异性抗血清和反义核酸的施用 阻断内源性92-kDa酶并确定其作用的寡核苷酸 在巨噬细胞介导的弹性蛋白溶解中;（3）原位杂交定位 92-kDa mRNA在肺气肿人肺组织中的表达，和（4） 组织病理学，以确定重组92-kDa 金属蛋白酶在实验动物的肺部。 这些研究将 为我们理解肺气肿的发病机制提供了新的思路 并将为肺气肿的预防和控制带来新的策略 和COPD。

Proteolytic activity that destroys lung elastic fibers is considered pivotal in the pathogenesis of pulmonary emphysema, a condition found primarily among smokers with chronic obstructive lung disease (COPD). Neutrophils and alveolar macrophages have been examined closely as possible sources for the elastase activity that causes emphysema. While some evidence suggests an important role for neutrophils, several observations point to alveolar macrophages as critical in the pathogenesis of emphysema in smokers: smokers' lungs have greatly increased (10 to 20 fold) numbers of macrophages, macrophages accumulate in smokers' lungs at precisely the sites of early emphysema, and macrophages are known to release a variety of proteinases that can attack components of the extracellular matrix. Furthermore, we have demonstrated that human alveolar macrophages cultured in contact with elastin have significant capacity to degrade this substrate via a mechanism which is near completely metalloproteinase-dependent. Despite these suggestive features, however, it has proven difficult to implicate human macrophages directly in the pathogenesis of emphysema because there has been limited evidence for a human macrophage enzyme with the capacity to degrade elastin. Recently, we discovered that one of the major proteinases released by human alveolar macrophages, a 92-kDa metalloproteinase, has pronounced elastolytic activity. This finding represents the first definitive demonstration of a neutral proteinase secreted by human macrophages that degrades elastin. To extend these initial observations we propose to examine in detail the elastolytic properties of the 92-kDa metalloproteinase, determine the role of this enzyme in the capacity of human alveolar macrophages to degrade elastin, look for evidence of excessive 92-kDa enzyme in human lung tissue affected with emphysema, and establish whether this human enzyme can produce pulmonary emphysema in experimental animals. These studies will use: (1) enzymologic techniques to define the binding affinity of the 92-kDa enzyme for elastin, its catalytic parameters, and sites of substrate cleavage; (2) specific antiserum to the 92-kDa enzyme and the administration of antisense oligonucleotides to block endogenous 92-kDa enzyme and determine its role in macrophage-mediated elastolysis; (3) in situ hybridization to localize expression of 92-kDa mRNA in emphysematous human lung tissues, and; (4) histopathology to determine the effects of recombinant 92-kDa metalloproteinase on the lungs of experimental animals. These studies will contribute new ideas to our understanding of the pathogenesis of emphysema and will lead to new strategies for the prevention and control of emphysema and COPD.