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Increased matrix metalloproteinase 9 activity and mRNA expression in lung ischemia-reperfusion injury
1Department of Surgery II, Nagoya City University School of Medicine, Nagoya, Japan.
Objectives:
In lung ischemia-reperfusion injury, neutrophil migration from the vasculature to the interstitial spaces plays a major role in tissue injury. Degradation of the basement membrane, which is composed of extracellular matrix (ECM) molecules, is necessary for neutrophil migration. Matrix metalloproteinases (MMPs) might play a role in ECM degradation in lung ischemia-reperfusion injury. We evaluated the changes in the activity of MMP-2 and MMP-9, and tissue inhibitor of metalloproteinase 1 (TIMP-1) gene expressions using rat lung transplantation models.
Methods:
We divided animals into 4 groups. Groups I and II served as control groups with intact lungs (Group I) and 24-hour cold-preserved lungs (Group II). Groups III and IV received lung grafts after 24-hour cold preservation. The recipient animals were sacrificed 1 hour (Group III) or 24 hours (Group IV) after transplantation. We evaluated lung injury histologically. We assessed MMP activity using zymography. We assessed MMP-2, MMP-9, and TIMP-1 gene expression using biplex reverse transcriptase-polymerase chain reaction method.
Results:
In Groups III and IV, we noted severe ischemia-reperfusion injury. We noted no significant difference in enzyme activity and gene expression of MMP-2 between Groups I and IV. The MMP-9 activity and gene expression were low during ischemia and increased on reperfusion. TIMP-1 gene expression was low during ischemia and at the early phase of reperfusion, and showed a dramatic increase at the late phase of reperfusion.
Conclusions:
Matrix metalloproteinase 9, but not MMP-2, may play an important role in ischemia-reperfusion injury. TIMP-1 increases at the late phase of reperfusion and may compensate for the activity of MMP-9.
Insights
Matrix metalloproteinase 9 (MMP-9) activity increases during lung reperfusion injury, suggesting its role in tissue damage. Tissue inhibitor of metalloproteinase 1 (TIMP-1) expression rises later, potentially to counteract MMP-9 effects.
Area of Science:
- Biomedical Engineering
- Translational Medicine
- Pulmonary Research
Background:
- Neutrophil migration is key in lung ischemia-reperfusion injury.
- Extracellular matrix degradation by matrix metalloproteinases (MMPs) facilitates this migration.
- The role of specific MMPs and their inhibitors in lung transplantation injury requires further elucidation.
Purpose of the Study:
- To investigate the gene expression and activity of MMP-2 and MMP-9.
- To assess the expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) in a rat lung transplantation model.
- To determine the involvement of these molecules in lung ischemia-reperfusion injury.
Main Methods:
- Rat lung transplantation model with 4 experimental groups (control, preserved, and transplanted at 1 and 24 hours).
- Histological evaluation of lung injury.
- Zymography to assess MMP activity.
- Biplex reverse transcriptase-polymerase chain reaction for MMP-2, MMP-9, and TIMP-1 gene expression.
Main Results:
- Significant ischemia-reperfusion injury observed in transplanted lungs.
- MMP-2 activity and gene expression showed no significant changes.
- MMP-9 activity and gene expression increased upon reperfusion.
- TIMP-1 gene expression was low during ischemia and early reperfusion, increasing dramatically in the late reperfusion phase.
Conclusions:
- Matrix metalloproteinase 9, not MMP-2, appears critical in lung ischemia-reperfusion injury.
- TIMP-1 upregulation late in reperfusion may serve a protective role by inhibiting MMP-9 activity.