Abstract 55: Involvement of Matrix Metalloproteinase-2 During the Progression of Renal Disease in Diabetic Dahl Salt-sensitive Rats

Abstract

Recently, our laboratory reported that Dahl salt-sensitive (SS) rats develop a form of renal disease following induction of diabetes with streptozotocin (STZ) that is similar to patients with diabetic nephropathy (DN). The progression of renal injury in this model was associated with increased levels of matrix metalloproteinase-2 (MMP-2) in the renal cortex. The present study examined the role of MMP-2 during the progression of diabetes-induced renal injury by comparing the development of proteinuria and renal injury following the induction of type I diabetes in SS rats and in a MMP-2 Zinc finger KO strain of SS rats with an 8 base pair frame-shift deletion (1433-1440) in exon 7 (MMP-2 ZN KO strain). The glomerular expression of MMP-2 protein was non-detectable in the MMP-2 ZN KO strain compared to SS rats fed a low salt (LS) diet. We next performed studies using 9 week-old SS and MMP-2 ZN KO rats treated with either vehicle or (2) STZ, 50 mg/kg (i.p.) to induce diabetes and fed the rats a low salt (LS) diet containing 0.4% NaCl to minimize the development of hypertension. At 18 weeks of age, protein excretion increased to 303±39 mg/day in STZ-treated SS rats (n=7) versus 112±12 mg/day in vehicle treated rats. Protein excretion only increased to 150±23 mg/day in the STZ-treated MMP-2 ZN KO strain (n=7). Blood pressure was not significantly altered and averaged 109±4 mmHg in vehicle and STZ-treated SS rats versus 108±4 mmHg in the STZ-treated MMP2-ZN KO animals. STZ-treated SS rats exhibited marked glomerular injury and extensive renal fibrosis. The degree of glomerulosclerosis and renal interstitial fibrosis was significantly reduced in the kidneys of the MMP-2 ZN KO strain. These data indicate that the progression of diabetes-induced renal injury in STZ-SS rats is associated with upregulation of the expression and activity of MMP-2 and that KO of MMP-2 gene function markedly reduces the development of proteinuria and renal injury in this model of type I diabetic nephropathy. These results also suggest that selective MMP inhibitors may be useful to prevent the development and/or progression of chronic kidney disease in the millions of patients suffering from diabetes.