Objective: To study the expression of matrix metalloproteinase-9 (MMP-9) in diabetic nephropathy of Kkay mice with hyperhomocysteinemia.
Methods: Sixteen Kkay mice were divided into two groups with 8 in each:diabetes group (KA) and methionine-diet group (KB). C57BL/6 mice were used as normal control (C57). Four months after being treated with two different diets, the mice were sacrificed and serum homocysteine (Hcy) was assayed with fluorescence polarization immunoassay. Renal pathological change was examined with periodic acid Schiff (PAS). The expression of MMP-9 protein and mRNA was detected with immunohistochemical staining and reverse transcriptase-PCR respectively.
Results: It was shown that induction of hyperhomocysteinemia in Kkay mice (KB) with a diet enriched in methionine aggravated diabetic nephropathy as compared with the KA group (P < 0.05). The expression of MMP-9 protein and mRNA in KB group was also enhanced and the mean positive area of MMP-9 in KB group was higher than that in KA group (15.90% vs 11.14%, P < 0.05).
Conclusion: The increased level of Hcy could worsen the nephropathy; this may be related to a higher expression of MMP-9.