Matrix metalloproteinase-mediated extracellular matrix protein degradation in human pulmonary emphysema

Lab Invest. 1998 Sep;78(9):1077-87.


The aim of this study was to investigate the extracellular degrading proteolytic cascade proteins referred to as matrix metalloproteinase-1 (MMP-1), MMP-2, MMP-9, membrane-type matrix metalloproteinase-1 (MT1-MMP), tissue inhibitors of matrix metalloproteinase-1 (TIMP-1), TIMP-2, neutrophil elastase, and alpha1-antitrypsin in human pulmonary emphysema. Localization of MMP-1, MMP-2, MMP-8, MMP-9, MT1-MMP, TIMP-1, and TIMP-2 was verified by immunohistochemical analysis. The results of our study indicated that the immunoreactivity of MMP-1, MMP-8, MMP-9, and TIMP-1 was absent, whereas MT1-MMP and MMP-2 were mainly observed in pneumocytes, fibroblasts, and alveolar macrophages. Although MT1-MMP and MMP-2 were observed both in emphysematous and normal lung tissue, these immunoreactivities were intense in the emphysematous samples. The presence of MMP-1, MMP-2, MMP-9, TIMP-1, and TIMP-2 was confirmed at mRNA level by reverse transcription-PCR analysis and enzyme immunoassay (EIA). However, the only statistical difference that was observed was in MMP-2 and MMP-9 (MMP-2: emphysematous samples, 19.1+/-2.1 versus control samples, 5.2+/-0.60 microg/g protein, p < 0.05; MMP-9: emphysematous samples, 18.4+/-5.6 versus control samples, 8.1+/-2.7 microg/g protein, p < 0.05). Results of the neutrophil elastase as analyzed by EIA, and alpha1-antitrypsin levels as detected by laser nephelometric immunoassay, indicated no statistical difference between the emphysematous and control groups. In addition to the presence of mRNA levels, the level of MT1-MMP according to immunoblot analysis increased in the emphysematous samples. Gelatin zymographic analysis confirmed the presence of both pro and active forms of MMP-2, and the increased ratio of the active form of MMP-2 in emphysematous samples (25.9%+/-2.0% versus 11.2%+/-3.3%, p < 0.05), indicated in situ activation of MMP-2 by MT1-MMP. Elastin zymographic analysis showed elastolytic activity by MMP-2 and MMP-9 but not the reported band of macrophage metalloelastase (MMP-12). The data suggest that the MT1-MMP/MMP-2/TIMP-2 system plays a significant role in the MMP-mediated extracellular matrix degradation and tissue remodeling of emphysematous lungs, and thus may contribute to the weakening of lung parenchyma and lead to the formation of emphysema.

MeSH terms

  • Aged
  • Cells, Cultured
  • Collagen / metabolism
  • Extracellular Matrix / enzymology*
  • Extracellular Matrix Proteins / metabolism*
  • Gelatin / metabolism
  • Humans
  • Immunohistochemistry
  • Leukocyte Elastase / metabolism
  • Male
  • Metalloendopeptidases / genetics
  • Metalloendopeptidases / physiology*
  • Middle Aged
  • Pulmonary Emphysema / metabolism*
  • Pulmonary Emphysema / pathology
  • RNA, Messenger / metabolism
  • Tissue Inhibitor of Metalloproteinase-1 / genetics
  • Tissue Inhibitor of Metalloproteinase-1 / metabolism
  • Tissue Inhibitor of Metalloproteinase-2 / genetics
  • Tissue Inhibitor of Metalloproteinase-2 / metabolism
  • alpha 1-Antitrypsin / metabolism


  • Extracellular Matrix Proteins
  • RNA, Messenger
  • Tissue Inhibitor of Metalloproteinase-1
  • alpha 1-Antitrypsin
  • Tissue Inhibitor of Metalloproteinase-2
  • Gelatin
  • Collagen
  • Leukocyte Elastase
  • Metalloendopeptidases