α-, γ- and δ-tocopherols reduce inflammatory angiogenesis in human microvascular endothelial cells

Vitamin E, a micronutrient (comprising α-, β-, γ- and δ-tocopherols, α-, β-, γ- and δ-tocotrienols), has documented antioxidant and non-antioxidant effects, some of which inhibit inflammation and angiogenesis. We compared the abilities of α-, γ- and δ-tocopherols to regulate human blood cytotoxicity (BEC) and lymphatic endothelial cytotoxicity (LEC), proliferation, invasiveness, permeability, capillary formation and suppression of TNF-α-induced VCAM-1 as in vitro models of inflammatory angiogenesis. α-, γ- and δ-tocopherols were not toxic to either cell type up to 40 μM. In BEC, confluent cell density was decreased by all concentrations of δ- and γ-tocopherol (10–40 μM) but not by α-tocopherol. LEC showed no change in cell density in response to tocopherols. δ-Tocopherol (40 μM), but not other isomers, decreased BEC invasiveness. In LEC, all doses of γ-tocopherol, as well as the highest dose of α-tocopherol (40 μM), decreased cell invasiveness. δ-Tocopherol had no effect on LEC invasiveness at any molarity. δ-Tocopherol dose dependently increased cell permeability at 48 h in BEC and LEC; α- and γ-tocopherols showed slight effects. Capillary tube formation was decreased by high dose (40 μM) concentrations of α-, γ- and δ-tocopherol, but showed no effects with smaller doses (10–20 μM) in BEC. γ-Tocopherol (10–20 μM) and α-tocopherol (10 μM), but not δ-tocopherol, increased LEC capillary tube formation. Lastly, in BEC, α-, γ- and δ-tocopherol each dose-dependently reduced TNF-α-induced expression of VCAM-1. In LEC, there was no significant change to TNF-α-induced VCAM-1 expression with any concentration of α-, γ- or δ-tocopherol. These data demonstrate that physiological levels (0–40 μM) of α-, γ- and δ-tocopherols are nontoxic and dietary tocopherols, especially δ-tocopherol, can limit several BEC and LEC endothelial behaviors associated with angiogenesis. Tocopherols may therefore represent important nutrient-signals that limit cell behaviors related to inflammation/angiogenesis, which when deficient, may predispose individuals to risks associated with elevated angiogenesis such as inflammation and cancer; further differences seen from the tocopherols may be due to their blood or lymphatic cell origin.