Abstract: Objective To assay the expression change of matrix metalloproteinasea-2 (MMP-2) and matrix metalloproteinasea-9 (MMP-9) in focal segmental glomerulosclerosis in rats, and to investigate the relationship between the expression of MMP-2 and MMP-9 and the accumulation of extracellular matrix (ECM) in the kidney in these rats. Materials and methods We divided 12 Wistar rats into test group and control group. The model of focal segmental glomerursclerosis (n = 7) was made by intravenous injection of puromycin aminonucleoside (PAN) 9mg/100g-1 body weight. Rats in control group (n = 5) were injected with 3ml 0.9% sodium chloride. Proteinuria and serum creatinine, lipids and protein were examined. Twenty weeks after the injection rats were sacrificed and their kidneys were taken for examination. Renal MMP-2, MMP-9 and fibronectin (FN) were examined by Immunohistochemistry. Positive immunohistochemical signals were quantitatively analysed using the Image-pro software. Results Rats in the test group had prominent protienuria and the increase of serum lipids. Pathologically, the kidney showed focal segmental sclerosis or sclerosis of the whole glomerulus in a part of glomeruli. ECM was segmentally accumulated in the kidney. MMP-9 normally expresses in glomerular endothelial and epithelial cells at a low level, but the expression decreased significantly in glomeruli of the rats in test group (P<0.05). There was no significant relationship between the MMP-9 expression and proteinuia. MMP-2 normally expresses in small renal arteries and the interstitium around renal tubules at a low level, but the expression decreased insignificantly in kidney of the rats in test group (P>0.05). FN normally expresses in glomeruli mesangial areas, glomerular basement membrane and renal interstitium, and the expression increased significantly in kidney of the rats in test group (P<0.05). FN expression negatively correlated with MMP-9 expression, but had no relationship with MMP-2 expression and proteinuria. Conclusion In the pathogenesis of focal segmental glomerulosclerosis, MMP-9 expression is down-regulated, resulting in the decrease of FN catabolism and the ECM accumulation.

Key words: Glomerular sclerosis