The Expression and Molecular Mechanisms of Matrix Metalloproteinase- 9 and Vascular Endothelial Growth Factor in Renal Interstitial Fibrosis in Rats.

Objective: To explore a new approach for the treatment of renal interstitial fibrosis (RIF), we detected the expression of matrix metalloproteinase-9 (MMP9) and vascular endothelial growth factor (VEGF).

Methods: Twenty-four male Sprague Dawley (SD) rats were randomly divided into 2- week normal control (2NC) group, 4-week NC (4NC) group, 2-week unilateral ureteral obstruction (2UUO) group, and 4-week UUO (4UUO) group. We performed left ureteral ligation on UUO groups. Then, we sacrificed the rats of the 2NC group and 2UUO group at 2 weeks and the other groups at 4 weeks after the surgery. Immunohistochemistry and western blot were applied to detect the expression of MMP9, VEGF, fibronectin (FN), type IV collagen (Col-IV), and transforming growth factor-β1 (TGF-β1). MMP9 levels reduced after UUO surgery. Its expression was less in the 4UUO group than in the 2UUO group (P<0.05). The expression of VEGF, TGF- β1, FN, and Col-IV was higher in UUO groups than in NC groups (P<0.05). The expression of these indicators was higher in the 4UUO group than in the 2UUO group (P<0.05).

Results: In the correlation analysis, MMP9 levels in UUO groups had a negative correlation with the expression of TGF-β1, VEGF, Col-IV, FN, and RIF index (all P<0.05). In UUO groups, VEGF levels had a positive correlation with the expression of TGF-β1, Col-IV, FN, and RIF index (all P<0.05).

Conclusion: In conclusion, with the aggravation of RIF lesions, MMP9 levels decreased, and VEGF levels increased. Whether there is a mutual inhibition relationship between them remains to be confirmed by further experiments.