LAUSR

Introduction: Apolipoproteins are key regulators of cholesterol transport and clearance with each apolipoprotein having a specific protective or atherogenic role. The relationship between subclinical cardiovascular risk and each of the apolipoproteins in the pediatric population is insufficiently described within the literature. Therefore, the purpose of this study was to examine the association of apolipoproteins with measures of vascular structure and function in pediatric population. Hypothesis: We hypothesized apolipoprotein AI, AII, and CII would demonstrate a positive association, and apolipoprotein B, B/AI ratio, CIII, CIII/CII ratio, and E a negative association with carotid intima-media thickness (cIMT) and carotid-radial pulse wave velocity (PWV). Methods: A cross-sectional study of 338 children and adolescents (160 males, 178 females) aged 8-21 years (mean age 13.0±2.8 years) with a range of adiposities from normal body weight to severe obesity (mean BMI 26.8±8.9 kg/m 2 ). Apolipoproteins (AI, AII, B, CII, CIII, and E) were measured via human apolipoprotein magnetic bead panel (Millipore, MA, USA). Ultrasound imaging of the carotid artery was used to measure cIMT. PWV, a measure of arterial stiffness, was assessed via applanation tonometry (SphygmoCor TM ). Total body fat percent (BF%) was measured using dual X-ray absorptiometry. Linear regression models were adjusted for Tanner stage, sex, and race with further adjustments for BF%. Data are presented as mean [95% CI] with Holms-adjusted p-values to account for multiple testing. All apolipoprotein ratios were scaled to 0.1 μg/mL. Methods: There were significant positive associations between PWV and apolipoproteins: AII (0.036 m/sec per 10 μg/mL [0.017, 0.056], p = 0.010), E (0.158 m/sec per 10 μg/mL [0.08, 0.235], p = 0.002), and CIII/CII ratio (0.033 [0.014, 0.052], p = 0.019). After adding BF% to the models, PWV remained positively associated with higher levels of apolipoproteins: AII (0.036 m/sec per 10 μg/mL [0.016, 0.055], p = 0.012), E (0.161 m/sec per 10 μg/mL [0.082, 0.239], p = 0.002), and CIII/CII ratio (0.033 [0.014, 0.052], p = 0.02). Before accounting for multiple testing, apolipoprotein CIII/CII ratio was positively associated with cIMT (0.001 [0, 0.003], p = 0.033), but failed to maintain significance after p-value correction. Otherwise, there were no significant associations between any apolipoprotein and cIMT in the presence or absence of BF%. Conclusions: These findings suggest higher levels of apolipoprotein AII, E, and CIII/CII ratio are associated with higher arterial stiffness (PWV) in pediatrics, both in the presence and absence of excess body fat. Apolipoproteins, specifically AII, E, and CIII/CII ratio, may exert their effects on vascular function (PWV) before altering vascular structure (cIMT), which is congruent with the chronological pathophysiology of atherosclerosis.