Vitamin E inhibits lipid peroxidation-induced adhesion molecule expression in endothelial cells and decreases soluble cell adhesion molecules in healthy subjects.

ABSTRACT

OBJECTIVE: In a combination of in vivo and in vitro studies, we investigated mechanisms via which alpha-tocopherol, a lipid soluble form of vitamin E, can directly affect endothelial activation as induced by H(2)O(2) and TNFalpha. METHODS: We measured effects of alpha-tocopherol on H(2)O(2)-induced lipid peroxidation as determined with a fluorescent C-11 BODIPY(581/591) probe and on adhesion molecule expression in cultured endothelial cells. In 20 healthy volunteers treated with increasing doses of alpha-tocopherol up to 800 IU/ml for 12 weeks, plasma levels of soluble cell adhesion molecules (sCAMs) and C-reactive protein were measured. RESULTS: We showed that alpha-tocopherol protects cultured endothelial cells against H(2)O(2)-induced lipid peroxidation, while TNFalpha did not induce lipid peroxidation. Moreover, alpha-tocopherol attenuated H(2)O(2)-, but not TNFalpha-induced increases in adhesion molecule expression. In healthy persons, alpha-tocopherol decreased plasma levels of sE-selectin from 65+/-6 to 60+/-6 ng/ml (P=0.002), sVCAM from 893+/-31 to 853+/-23 ng/ml (P=0.022), and sICAM from 483+/-21 to 463+/-16 ng/ml (P=0.048). C-Reactive protein, as a sensitive marker of low grade inflammation, was not significantly affected. CONCLUSION: alpha-Tocopherol specifically inhibits lipid peroxidation-induced endothelial activation in vitro. The observed vitamin E-induced decrease in sCAMs in control subjects suggests that lipid peroxidation can take place in healthy individuals. Although vitamin E supplementation may be especially effective in specific groups of patients exposed to increased oxidative stress, our study suggests that vitamin E supplementation can be of benefit in healthy individuals as well.