ROLE OF ELASTOLYTIC METALLOPROTEINASES IN EMPHYSEMA

破坏肺弹性纤维的蛋白分解活性被认为是 发现肺气肿在肺气肿发病机制中的关键作用 主要是患有慢性阻塞性肺疾病(COPD)的吸烟者。 对中性粒细胞和肺泡巨噬细胞进行了尽可能仔细的检查。 导致肺气肿的弹性蛋白酶活性的来源。虽然有些人 多项观察显示，有证据表明中性粒细胞起着重要作用 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：吸烟者的肺数量大大增加(10到20倍) 巨噬细胞中，巨噬细胞在吸烟者的肺中积聚的 已知早期肺气肿的部位和巨噬细胞会释放各种不同的 可以攻击细胞外基质成分的蛋白酶。 此外，我们还证明了培养的人肺泡巨噬细胞 与弹性蛋白接触时具有显著降解该底物能力 通过一种几乎完全依赖于金属蛋白酶的机制。 然而，尽管有这些提示性的功能，事实证明很难 人巨噬细胞直接参与肺气肿的发病机制 因为有有限的证据表明人类巨噬细胞酶具有 降解弹性蛋白的能力。最近，我们发现其中一个 人肺泡巨噬细胞释放的92 kDa主要蛋白酶 金属蛋白酶，具有显著的弹性溶解活性。这一发现 代表了中性蛋白水解酶的第一个确凿的演示。 由人类巨噬细胞分泌，可降解弹性蛋白。要扩展这些功能 我们建议详细研究弹性裂解的初步观察 92 kDa金属蛋白酶的性质，决定了它的作用 人肺泡巨噬细胞降解弹性蛋白能力中的酶， 寻找受影响的人肺组织中92 kDa酶过量的证据 肺气肿，并确定这种人类酶是否能产生 实验动物的肺气肿。这些研究将使用：(1) 确定92-kDa酶结合亲和力的酶学技术 弹性蛋白、其催化参数和底物裂解位置；(2) 92 kDa酶的特异性抗血清及其反义给药 寡核苷酸阻断内源性92 kDa酶及其作用的研究 巨噬细胞介导的弹性溶解；(3)原位杂交定位 92-kDa基因在肺气肿患者肺组织中的表达 用组织病理学方法检测重组92-kDa的作用 实验动物肺组织中的金属蛋白酶。这些研究将 为我们理解肺气肿的发病机制提供新的思路 并将导致新的肺气肿防治策略 和慢性阻塞性肺病。

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.