Differential glomerular immunoexpression of matrix metalloproteinases MMP-2 and MMP-9 in idiopathic IgA nephropathy and Schoenlein-Henoch nephritis.

Abstract

Both idiopathic IgA nephropathy (IgAN) and Schoenlein-Henoch nephritis (SHN) are characterized by cell proliferation and abnormal extracellular matrix (ECM) remodeling by mesangial cells leading to fibrosis, sclerosis and end-stage renal disease. Matrix metalloproteinases MMP-2 and MMP-9 are reported as the most important proteolytic enzymes involved in remodeling of ECM. Therefore, the aim of the present study was to determine glomerular immunoexpression of MMP-2 and MMP-9 in IgAN and SHN. Another purpose of this study was to examine the relationship between expression of MMPs and mesangial cells, a-smooth muscle actin (alpha-SMA) staining, and monocytes/macrophages. Fifteen patients with idiopathic IgAN and 12 with SHN were examined by percutaneous renal biopsy. Glomerular staining intensity of MMP-2 and MMP-9 was recorded semiquantitatively, whereas mesangial cells, glomerular alpha-SMA staining and glomerular CD 68+ cells were assessed quantitatively using computer image analysis system. Our study revealed that the mean values of glomerular immunoexpression of MMP-2, mesangial cells, alpha-SMA staining and glomerular CD 68+ cells were in SHN patients significantly increased as compared to IgAN cases whereas glomerular staining for MMP-9 did not differ in these groups. Moreover, a glomerular staining of MMP-2 was significantly positively correlated with mesangial cells as well as glomerular alpha-SMA staining in both SHN and IgAN. A positive significant correlation between glomerular MMP-2 staining and glomerular CD68+ cells was noted only in SHN group. The correlations of glomerular MMP-9 and these parameters were weak and not significant. In conclusion, our results confirm increased glomerular staining of MMP-2 but not MMP-9 in SHN patients. A suggestion that augmented mesangial cells proliferation in these cases depends on MMP-2, alpha-SMA and monocytes/macrophages needs further investigations including double staining study.