Altered matrix metalloproteinase 9 and tissue inhibitor of metalloproteinases 1 levels in children with primary hypertension

BACKGROUND: Matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) are involved in cardiovascular remodeling in hypertension. Because metabolic abnormalities typical of metabolic syndrome is the dominant phenotype of primary hypertension in children, we hypothesized that MMP-9 and TIMP-1 plasma concentrations are altered in hypertensive children and correlate with metabolic abnormalities and target organ damage. METHOD: A total of 109 children (15.6, 10-17 years) with untreated primary hypertension were included to the study. The control group consisted of 74 healthy, normotensive children. RESULTS: Plasma MMP-9, TIMP-1 concentrations, and MMP-9/TIMP-1 ratio were significantly elevated in hypertensive boys in comparison with normotensive boys (P = 0.0001, P = 0.04, and P = 0.001, respectively), whereas there were no differences between hypertensive and normotensive girls. The levels of MMP-9 and TIMP-1 as well as MMP-9/TIMP-1 ratio were not associated either with hypertension stage, left ventricular hypertrophy, or carotid intima-media thickness. However, in a subgroup of 30 hypertensive patients in whom arterial stiffness was measured, TIMP-1 concentrations correlated with aortic pulse pressure (P < 0.05; r = 0.367), augmentation pressure (P < 0.05; r = 0.428), and augmentation index (P < 0.05; r = 0.404).Only hypertensive boys presented negative correlations of both MMP-9 and TIMP-1 levels with high-density lipoprotein cholesterol (r = -0.254, P = 0.01 and r = -0.241, P = 0.02, respectively). CONCLUSION: Hypertensive boys but not girls had elevated MMP-9 and TIMP-1 plasma concentrations, which indicates sex-related role of MMP/TIMP system in pediatric hypertension. The correlation between serum TIMP-1 and markers of arterial stiffness indicates on the involvement of TIMPs in arterial remodeling.