Microrna-133a and Microrna-145 as Promising Biomarkers of Hypertension Mediated Organ Damage in Adolescents With Primary Hypertension – A Preliminary Study

Objective: Studies based on data from adults show an important role of microRNAs in the development of hypertension and their impact on hypertension-mediated organ damage (HMOD). The aim was to examine the expression of miR-21, miR-27a, miR-27b, miR-133a, and miR-145 in hypertensive pediatric patients and reveal their correlation with blood pressure parameters, properties of the arteries, and myocardial hypertrophy. Design and method: In 22 teenagers (18 boys, 4 girls, 15.1±1.9 years) with primary hypertension, we assessed mentioned above microRNA expression levels before and after one hour of aerobic exercise session, office and 24-hour ambulatory blood pressure and HMOD indicators, such as left ventricle mass index (LVMI), urinary albumin-creatine ratio, pulse wave velocity (PWV), and carotid intima-media thickness (cIMT). Relative microRNA expression was calculated with the 2^-δδCt method with miR-16 as endogenous control and baseline (before exercise session) microRNA expression taken as a control value. Results: In the studied children, we observed significant decrease in both office and 24 hour ambulatory diastolic blood pressure after one-hour exercise (82.2±8.5 vs. 78.6±8.8 [mm Hg], p=0.01 and 75.0±8.3 vs. 73.0±7.4 [mm Hg], p=0.02). In the whole group there were no significant changes in expression of the studied microRNA molecules after an exercise session. The post-exercise increase in miR-133a expression level showed a positive correlation with LVMI [g/m2.7] (R=0.491, p=0.02). Conversely, post-exercise increase in miR-145 expression correlated negatively with post-exercise both systolic and diastolic office and 24-hour blood pressure, 24-hour PWV, and cIMT (R=-0.428, p=0.047 and R=-0.430; p=0.046, and R=-0.455, p=0.033, respectively). None of the studied microRNA molecules correlated with age. Conclusions: 1.MicroRNA-133a might be a marker of left ventricular hypertrophy in children with primary hypertension. 2. Exercise-induced change in microRNA-145 expression may lower post-exercise blood pressure and have a protective effect against arterial damage in children with primary hypertension. 3. Both miR-133a and miR-145 may be involved in epigenetic modifications in pediatric patients with primary hypertension influencing HMOD.