Circulating vascular biomarkers in relation to physiological indices of aortic stiffness and endothelial function in hypertension

Studies investigating the relation between circulating vascular biomarkers reflecting endothelial dysfunction and physiological methods to evaluate vascular function remain limited. We simultaneously evaluated the relation between circulating endothelial biomarkers with physiological non-invasive vascular methods in 107 hypertensive patients with a wide range of mean estimated glomerular filtration rate (eGFR). Endothelial glycocalyx hyaluronan (HA) and syndecan-1 (SDC-1), and cellular adhesion molecules (ICAM-1, VCAM-1, and E-selectin) were measured by enzyme-linked immunosorbent assays. Aortic stiffness (cfPWV) was assessed by pulse wave analysis. Endothelial function in different vascular beds was evaluated physiological by methods: flow mediated vasodilation (large arteries), pulse wave analysis and the reflection index change, using beta 2-adrenoceptor agonist stimulation (smaller resistance arteries), and laser Doppler fluxmetry and iontophoresis (skin microvascular function). Diastolic function and left atrial size were assessed by echocardiography. Mean blood pressure (BP) was 149 ± 17/87 ± 10 mm Hg, mean eGFR 74 (21-130) ml/min x 1.73 m². HA was independently related to cfPWV (β = 0.23, P = 0.02), whereas SDC-1 was independently inversely related to skin microvascular function, (β= - 0.27, P = 0.042) and was independently related to resistance artery endothelial function (β = 0.29, P = 0.026). All circulating biomarkers were unrelated to physiologically measured large artery endothelial function, and with echocardiographic parameters. The glycocalyx markers were associated with physiological vascular measures independent of eGFR but should not be considered as a proxy for these measures, due to the weak relations. However, combining circulating markers with physiological measures might give additional information about vascular function.