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Macrophage-derived MT1-MMP and increased MMP-2 activity are associated with glomerular damage in crescentic
K Hayashi1, S Horikoshi, S Osada
1Division of Nephrology, Department of Medicine, Juntendo University School of Medicine, Tokyo, Japan.
Abstract:
Membrane-type matrix metalloproteinases (MT-MMPs) have been shown to activate pro-MMP-2 on the cell surface and are suggested to be key enzymes in tissue remodelling under various physiological and pathological conditions. To investigate the role of MT-MMP in progressive renal injury, the gene expression and enzymatic activity of MT-MMP were examined in crescentic glomerulonephritis induced by anti-glomerular basement membrane (GBM) antibody in WKY rats. Isolated glomeruli were subjected to RNA and protein extraction 0, 1, 3, 7, 14, and 28 days after intravenous injection of rabbit anti-GBM antibody. Semiquantitative RT-PCR analysis revealed that among the three members of the MT-MMP family, mRNA expression of MT2-MMP remained unchanged and that of MT3-MMP was not observed in glomeruli during the development of nephritis. However, MT1-MMP gene expression increased from day 3 and reached maximum levels at day 7 (5.5+/-0.7-fold increase over day 0), closely associated with macrophage accumulation, crescent formation, and increased proteinuria. Gelatin zymography showed that the active from of MMP-2 emerged from day 7 and remained during the experimental period accompanied by increased proMMP-2, while no active form of MMP-2 was found in control rats. Using an antisense cRNA probe, intense signals of MT1-MMP mRNA were observed mostly in cells within the crescent and in some cells in the mesangial areas. Most of these cells were ED-1-positive macrophages, based on immunostaining of sequential sections. These results suggested that in the MT-MMP family, MT1-MMP was induced in infiltrating macrophages during the development of crescentic glomerulonephritis and possibly contributed to pathological degradation of glomerular extracellular matrices through the activation of proMMP-2.
Insights
Membrane-type matrix metalloproteinases (MT-MMPs) play a role in kidney injury. MT1-MMP, a specific MT-MMP, is upregulated in macrophages during glomerulonephritis, potentially driving extracellular matrix degradation and renal damage.
Area of Science:
- Nephrology
- Molecular Biology
- Pathology
Background:
- Membrane-type matrix metalloproteinases (MT-MMPs) activate pro-MMP-2, influencing tissue remodeling in physiological and pathological states.
- Their specific role in progressive renal injury, particularly crescentic glomerulonephritis, requires further investigation.
Purpose of the Study:
- To investigate the gene expression and enzymatic activity of MT-MMPs in a rat model of crescentic glomerulonephritis.
- To determine the contribution of MT1-MMP to the pathogenesis of progressive renal injury.
Main Methods:
- Induction of crescentic glomerulonephritis in WKY rats using anti-glomerular basement membrane (GBM) antibody.
- Analysis of MT-MMP gene expression (RT-PCR) and activity (gelatin zymography) in isolated glomeruli over 28 days.
- Localization of MT1-MMP mRNA using antisense cRNA probes and colocalization with macrophages (ED-1 staining).
Main Results:
- MT1-MMP gene expression significantly increased from day 3, peaking at day 7, correlating with macrophage infiltration, crescent formation, and proteinuria.
- Active MMP-2 emerged from day 7 onwards, coinciding with increased proMMP-2 levels.
- MT1-MMP mRNA was predominantly found in infiltrating ED-1-positive macrophages within glomerular crescents and mesangial areas.
Conclusions:
- MT1-MMP is induced in macrophages during crescentic glomerulonephritis development.
- MT1-MMP activation of pro-MMP-2 likely contributes to the pathological degradation of glomerular extracellular matrix in progressive renal injury.