Glomerular expression of matrix metalloproteinases in systemic lupus erythematosus in association with activity index and renal function.

PURPOSE: The aim of this study was to examine the expression of matrix metalloproteinases (MMPs) MMP-1, MMP-2, MMP-3, MMP-9, and their specific tissue inhibitor TIMP-1 in kidney biopsies of patients with lupus nephritis (LN) and to investigate the relationship between MMPs, activity index, and renal function at the time of kidney biopsy. METHODS: We performed immunohistochemistry with monoclonal antibodies against MMP-1, MMP-2, MMP-3, MMP-9, and TIMP-1 in 58 kidney-biopsy specimens with LN (according to the 2004 ISN/RPS classification) and eight specimens from normal kidney tissue. We used clinical data of 36 patients at the time of kidney biopsy to evaluate the association between MMPs expression and renal function. RESULTS: We found increased MMP-1, MMP-2, and MMP-3 expression in LN glomeruli and a significant correlation with the activity features, with higher activity index score and worse renal function (p < .001). In particular, we have noticed a significant correlation of MMP-1 with leukocyte influx (OR:16.5 95%CI 4.3-62.5 p < .001), and MMP-3 with glomerular hypercellularity (OR:18.6 95%CI 4.8-72.8 p < .001). Moreover, we found a strong correlation of MMP-2 expression with fibrinoid necrosis and cellular crescents formation (OR:17.1 95%CI 4.3-67.7 p < .001). CONCLUSIONS: MMP expression in renal biopsy of patients with LN is increased and directly related to a highly active inflammatory response. Moreover, stronger MMP expression is associated with higher activity index and a more profound renal dysfunction.

Glomerular expression of matrix metalloproteinases in AL-amyloidosis and association with renal function at the time of kidney biopsy.

BACKGROUND: Matrix metalloproteinases (MMPs) have been implicated in the pathophysiology of various renal diseases, however, there are limited data regarding their role in renal AL-amyloidosis. In the present study, we evaluated the glomerular expression of MMPs in renal-biopsy specimens containing AL-amyloid deposits. We also examined the association of MMPs with renal function at the time of diagnostic renal biopsy. METHODS: We performed immunohistochemistry with monoclonal antibodies against MMP-1, MMP-2, MMP-3, MMP-9, and TIMP-1 in 19 kidney-biopsy specimens with AL-amyloidosis and 8 specimens from normal kidney tissue. We used clinical data of the patients at the time of kidney biopsy to evaluate the association between MMP expression and renal function. RESULTS: We found increased MMP-1 and MMP-3 expression within the amyloid deposits and adjacent tissues in > 50% of the amyloid-positive biopsies, whereas MMP-1 and MMP-3 were negative in control samples. In contrast, we found no significant glomerular MMP-2 and TIMP-1 expression in amyloid-containing or normal kidneys. MMP-9 expression was found in the glomerular basement membrane equally in AL-amyloidosis and control specimens. The presence of MMP-1 and MMP-3 in the glomeruli of patients with AL-amyloidosis correlated with worse renal function at the time of kidney biopsy. CONCLUSION: The findings of this study show increased glomerular expression of MMP-1 and MMP-3 in patients with AL-amyloidosis which is associated with worse renal function at the time of the kidney biopsy. Our results suggest an important role for MMP-1 and MMP-3 in the pathogenesis of renal damage in AL-amyloidosis.