CIRCULATING LEVELS OF MATRIX METALLOPROTEINASE-9 ARE ELEVATED IN INDIVIDUALS WITH HYPERTENSIVE CRISIS

Abstract

Objective: Matrix metalloproteinase-9 (MMP-9) participates in the degradation of components of the extracellular matrix and it is involved on vascular remodeling. The imbalance between their activation and inactivation mechanisms seems to be associated with vasomotor changes. The aim of this study was to investigate the plasma levels of MMP-9 in acute vascular alterations due to hypertensive crisis. Design and method: This cross-sectional study was performed in 40 normotensive (NT) and 58 controlled hypertensive subjects (CHyp) as well in 57 patients with hypertensive emergency (HypEmerg) and 43 in hypertensive urgency (HypUrg). Hypertensive crisis was divided in HypEmerg, which was characterized by elevated levels of systolic blood pressure (BP) higher or equal 180 mmHg and/or diastolic BP higher or equal 120 mmHg complicated with target-organ damage (TOD), and HypUrg, defined by BP elevation without TOD. The levels of MMP-9 were assessed using the Human Matrix metalloproteinase-9 Quantikine ELISA kit (R & D Systems, Inc., Minneapolis, MN, USA) with a calculation of medians being presented as nanograms per milliliter (ng/mL). Subsequently, MMP-9 values were transformed into logarithms to reflect normal distribution for statistical analysis. Results: The mean blood pressures were 116.5 ± 13.9/72.4 ± 10.6 mmHg for NT, 123.2 ± 12.6/79 ± 9.2 for CHyp, 194.1 ± 24.3/121.4 ± 17.3 for HypUrg and 191.6 ± 34.3/121.7 ± 18.8 mmHg for HypEmerg, respectively (p-value < 0.0001 between groups). MMP-9 levels were statistically different between the HypEmerg (log 2.31 ± 0.2) and HypUrg groups (log 2.17 ± 0.3) compared to the NT (log 1.94 ± 0.3) (p-value < 0.01 and p-value < 0.05, respectively) and CHyp groups (log 1.92 ± 0.2) (p-value < 0.01). There was no difference in the MMP-9 levels between the different clinical presentations of hypertensive crisis. Conclusions: Matrix metalloproteinase-9 concentrations are progressively higher in the order normotensive, controlled hypertensive, hypertensive urgency and emergency groups with significant differences between the hypertensive crisis groups (urgency and emergency) compared to the other groups. Therefore, MMP-9 may be a new biomarker in cases of acute elevations of blood pressure.