Related Experiment Videos
Matrix metalloproteinase-mediated extracellular matrix protein degradation in human pulmonary emphysema
K Ohnishi1, M Takagi, Y Kurokawa
1Second Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Abstract:
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.
Insights
Matrix metalloproteinase-2 (MMP-2) and MMP-9 levels are significantly elevated in pulmonary emphysema, suggesting their role in lung tissue degradation. The MT1-MMP/MMP-2/TIMP-2 system is implicated in extracellular matrix remodeling in emphysema.
Area of Science:
- Biochemistry
- Pulmonary Medicine
- Molecular Biology
Background:
- Pulmonary emphysema involves the degradation of lung extracellular matrix.
- Matrix metalloproteinases (MMPs) are key enzymes in tissue remodeling.
- Understanding the specific MMPs involved in emphysema pathogenesis is crucial.
Purpose of the Study:
- To investigate the expression and activity of specific MMPs and their inhibitors in human pulmonary emphysema.
- To elucidate the role of the MT1-MMP/MMP-2/TIMP-2 system in emphysema.
Main Methods:
- Immunohistochemistry to localize MMPs and TIMPs.
- Reverse transcription-PCR and enzyme immunoassay (EIA) to quantify MMP and TIMP levels.
- Immunoblot analysis and zymography to assess protein levels, activation states, and enzymatic activity.
Main Results:
- Elevated levels and intense immunoreactivity of membrane-type matrix metalloproteinase-1 (MT1-MMP) and MMP-2 in emphysematous lung tissue.
- Significantly increased MMP-2 and MMP-9 levels in emphysematous samples compared to controls.
- Evidence of in situ activation of MMP-2 by MT1-MMP and elastolytic activity by MMP-2 and MMP-9.
Conclusions:
- The MT1-MMP/MMP-2/TIMP-2 system plays a significant role in extracellular matrix degradation in emphysema.
- Increased MMP-2 activation contributes to lung parenchyma weakening and emphysema formation.
- MMP-2 and MMP-9 are key players in the proteolytic cascade leading to emphysema.