Carotid artery stiffness, high-density lipoprotein cholesterol and inflammation in men with pre-hypertension

Low circulating levels of high-density lipoprotein cholesterol (HDL-C) are associated with increased risk for cardiovascular events. HDL-C has a variety of poorly understood atheroprotective effects, including altering lipid metabolism and reducing inflammation. Increased arterial stiffness is an important predictor of subsequent cardiovascular risk. Therefore, in this study, we sought to determine whether HDL-C levels are associated with carotid arterial stiffness. In addition, we examined potential correlates of this association, such as inflammatory factors, cardiorespiratory fitness and body fat percentage. Carotid artery β-stiffness was measured by ultrasound in 47 (23 years old) healthy pre-hypertensive men. Low HDL-C was defined as < 1.0 mmoll^-1. Body fat was measured by air displacement plethysmography. Cardiorespiratory fitness was measured using a maximal exercise test, with metabolic gas analysis and inflammatory markers consisting of C-reactive protein (CRP), white blood cell (WBC) count and absolute neutrophil count. Men with a low HDL-C had significantly higher carotid artery stiffness, CRP, WBC count, neutrophil count, body fat, fasting glucose and lower cardiorespiratory fitness (P<0.05). Co-varying for cardiorespiratory fitness, % body fat and glucose had no effect on group differences in carotid artery stiffness. Co-varying for inflammatory markers resulted in groups having similar carotid artery stiffness. Pre-hypertensive men with low HDL-C have a higher carotid artery stiffness when compared with those with higher HDL-C. The detrimental effects of low HDL-C on large artery stiffness in pre-hypertensive men may be mediated by inflammation and not by cardiorespiratory fitness or body fat levels.