Matrix Metalloproteinase (MMP)-9 Levels in Children on Hemodialysis: Association with MMP-9 C(-1562)T Gene Polymorphism and Vitamin D Levels.

BACKGROUND AND OBJECTIVES: Data concerning the concentration of matrix metalloproteinase-9 (MMP-9) and its functional polymorphisms in chronic kidney diseases (CKD) are conflicting. The present study aimed to evaluate the levels of MMP-9in children with end stage renal diseases (ESRD) on hemodialysis (HD) and to explore its association with MMP-9 polymorphism and vitamin D levels as an important risk factors for cardiovascular diseases (CVD).

METHODS: We studied 55 children with ESRD on hemodialysis and 18 healthy children served as controls. MMP-9 and vitamin D levels were measured by ELISA in serum of all patients and controls. Genotypes for MMP-9 polymorphism(C(-1562)T) were determined by RFLP for only 28 of the patients and all the controls.

RESULTS: There were insignificantly reduced MMP-9levels of patients vs. controls, however, there was significant increase in MMP-9 levels associated with CC genotypes for(C(-1562)T) polymorphism compared with CT genotype (p=0.01). We found that at MMP-9 base position-1562, the frequencies of the genotypes CC and CT in Children on HD were 71.4% and 28.6% respectively while all our controls were of the CC genotype. The alleles frequencies of C and T in patients were 85.7% and 14.29% as compared to 100% and 0%, respectively in the controls. Significant decrease in vitamin D was observed in children on HD versus that in controls (p=0.008). Serum MMP9 levels and age were variables that were independently associated with CVD.

CONCLUSIONS: MMP9 genetic polymorphism (C(-1562)T) affects MMP9alterations in ESRD children on HD and vitamin D deficiency is common in our HD pediatric patients who require attention in accordance with current practice guidelines. They probably require supplementation with higher doses of cholecalciferol.