Neutral metalloproteinases in human urine from normal patients and renal disease patients

Summary: We examined the activity and the characteristics of gelatinolytic enzymes in the urine from normal subjects and the patients with glomerulonephritis (GN). Gelatinolytic activity was assayed by using [3H]gelatin (heat-denatured type I collagen) as a substrate. the activity found to be 2463 ± 204 U/day (mean ± SEM, n = 17) in the urine from the healthy individuals, but was negligible in plasma samples. In GN patients (n=24) urinary gelatinolytic activity (724± 149 U/day, P < 0.001) was significantly lower compared with the healthy individuals. Partial purification (anion exchange column chromatography followed by gel filtration) revealed that two active gelatinolytic enzymes (molecular weight [Mr]92 kDa; high molecular weight [HMW] gelatinase, Mr 40 kDa; low molecular weight [LMW] gelatinase) were present in the urine obtained from the healthy individuals. the activity of these enzymes was inhibited by EDTA, 1,10-phenanthroline and α2-macroglobulin, but not by inhibitors for serine, cystein and aspartic proteinase. As the optimum pH was in the neutral range (pH 6–9), these gelatinases were considered to be neutral endometalloproteinases. These enzymes could degrade acid soluble type IV collagen and native rat glomerular basement membrane (GBM) in addition to gelatin, but not type I collagen. Immunoblotting with antibodies against human metalloproteinases (MP) identified HMW gelatinase with matrix metalloproteinase (MMP)-9 (gelatinase B) and LMW gelatinase with MMP-2 (gelatinase A), respectively. As these enzymes are metalloproteinase (MP) capable of degrading GBM and its component, urinary MP may be a useful subject as a tool searching the metabolic alteration of glomerular extracellular matrix in renal diseases.