Background: Antioxidants may prevent atherosclerosis by interfering with endothelial activation, which involves the expression of endothelial adhesion molecules. The aim of this study was to explore the relationship between plasma levels of some lipid-soluble antioxidants (gamma-tocopherol, alpha-tocopherol, lycopene, beta-carotene, and ubiquinone), carotid maximum intima-media thickness (IMTmax), an index of atherosclerotic extension/severity, and soluble adhesion molecules (vascular cell adhesion molecule-1 [VCAM-1], intercellular adhesion molecule-1 [ICAM-1], and E-selectin), which are taken as a reflection of vascular cell expression of adhesion molecules.
Methods: We studied 11 healthy control subjects, 11 patients with uncomplicated hypertension (UH), and 11 patients with essential hypertension plus peripheral vascular disease (PVD) who were matched for age, sex, smoking habit, and body mass index.
Results: Patients with PVD had elevated IMTmax (2.7 [1.1-3.1] mm, median [range]) compared with both patients with UH(1.2 [0.8-2.4] mm) and control subjects (1.0 [0.6-2] mm). In patients with PVD, soluble (s)VCAM-1 and sICAM-1 were also significantly higher than in the 2 other categories. Plasma levels of lycopene had a trend toward lower values in patients with PVD compared with other groups (P =.13). A statistically significant correlation was found between lycopene and IMTmax (r = 0.42, P =.014) at univariate analysis, which persisted at multivariate analysis (P <.05) and was independent of low-density lipoprotein cholesterol, creatinine clearance, and plasma insulin. Plasma lycopene did not significantly correlate with any of the soluble adhesion molecules tested.
Conclusions: We conclude that the inverse relationship of plasma lycopene with IMTmax is compatible with a protective role of this natural dietary antioxidant in atherosclerosis, although the mechanism of protection does not apparently involve a decrease in endothelial activation measured through soluble adhesion molecules.