Sanders J-S, Huitema MG, Hanemaaijer R, van Goor H, Kallenberg CG, Stegeman CA. Urinary matrix metalloproteinases reflect renal damage in anti-neutrophil cytoplasm autoantibody-associated vasculitis. Am J Physiol Renal Physiol 293: F1927-F1934, 2007. First published September 26, 2007; doi:10.1152/ajprenal.00310.2007.-Renal expression of MMP-2, -9, and tissue inhibitor of MMP-1 (TIMP-1) correlates with histological disease activity in anti-neutrophil cytoplasm autoantibody (ANCA)-associated vasculitis (AAV). We studied whether urinary and plasma levels of MMP-2, -9, and TIMP-1 reflect renal expression of these proteins and renal disease-activity in AAV. Urine and plasma samples of patients with AAV who underwent a renal biopsy were collected (n ϭ 32). Urinary activity of MMP-2 and -9 was measured by activity assays. Urinary and plasma levels of MMP-2, MMP-9, and TIMP-1 proteins were measured by ELISA. Healthy controls provided plasma and urine for comparison (n ϭ 31). In patients, the relationship of urinary and plasma levels with renal expression of MMP-2 and MMP-9 and clinical and histological disease activity was studied. Renal MMP expression was compared between patients and controls (n ϭ 8). Urinary MMP-2 and MMP-9 activity and urinary and plasma TIMP-1 levels were significantly higher in patients than in controls. In glomeruli of patients, both MMP-2 and MMP-9 expression reflected active glomerular inflammation. Urinary activity of MMP-2 and MMP-9 did not correlate with renal MMP expression or plasma levels. Urinary MMP activity correlated negatively with glomerular inflammation, but positively with fibrous crescents. Urinary MMP-2 and TIMP-1 levels showed a positive correlation with tubulointerstitial damage and a negative correlation with creatinine clearance. Urinary MMP-2, MMP-9, and TIMP-1 are elevated in AAV but do not reflect renal MMP expression and glomerular inflammation. However, urinary MMP-2 activity and TIMP-1 levels reflect tubulointerstitial damage and correlate negatively with creatinine clearance at biopsy.ANCA-associated vasculitis; crescentic glomerulonephritis; MMP-2; MMP-9; TIMP-1; immunohistochemistry; urinary levels; plasma levels MANY PATIENTS WITH VASCULITIS associated with anti-neutrophil cytoplasmic autoantibodies (ANCA) develop pauci-immune necrotizing crescentic glomerulonephritis, which is frequently associated with rapidly progressive deterioration of renal function (5). Although the pathogenesis of this glomerulonephritis is not precisely known, leukocyte infiltration, matrix degradation, and necrosis are essential steps in disease development. Following institution of immunosuppressive treatment, some glomeruli with active crescentic lesions resolve with improvement of glomerular function, whereas others become acellular and fibrotic leading to permanent loss of glomerular function (8).The role of matrix metalloproteinases (MMPs) in glomerular disease is increasingly appreciated. MMPs mediate both degradation of extracellular matrix components and cell proliferation and fa...