Matrix metalloproteinase-mediated extracellular matrix protein degradation in human pulmonary emphysema.
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.
Ohnishi
K
K
Second Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Takagi
M
M
Kurokawa
Y
Y
Satomi
S
S
Konttinen
Y T
YT
D000368:Aged; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix / Q000201:enzymology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005780:Gelatin / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D019272:Leukocyte Elastase / Q000378:metabolism; D008297:Male; D008666:Metalloendopeptidases / Q000235:genetics / Q000502:physiology*; D008875:Middle Aged; D011656:Pulmonary Emphysema / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000378:metabolism
D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; D019715:Tissue Inhibitor of Metalloproteinase-1; D000515:alpha 1-Antitrypsin; D019716:Tissue Inhibitor of Metalloproteinase-2; D005780:Gelatin; D003094:Collagen; D019272:Leukocyte Elastase; D008666:Metalloendopeptidases