Effect of γ- (γ-T) and α- (α-T) tocopherol on adhesion molecule expression and prostaglandin (PG) production in Human Aortic Endothelial Cells (HAEC)

Abstract

While many studies focus on α-T, γ-T consumption may account for 70% of tocopherol ingestion in the US diet. One proposed action of E on vascular function is via modulation of adhesion molecule expression and PG production. We incubated HAEC with increasing equimolar concentrations of γ-T or α-T for 20h. Cellular γ-T and α-T levels increased (p<0.05) to 17.4 ± 2.3, 27.3±3.2, and 39.6±4.0 and 9.3±2.9, 16.3±2.0, and 28.4 ± 2.9 pmol//μg protein after incubation with 20, 40, and 60 μM T, respectively. Cell γ-T and α-T levels differed at each concentration. Expression of HAEC adhesion molecules VCAM, ELAM, and ICAM increased by 17, 29, and 3-fold (p<0.05), respectively, after incubation with interleukin (IL)-1β. VCAM expression was reduced by 16, 27, and 32% with γ-T and 18, 29, and 28% with α-T. ELAM expression was reduced by 13, 25, and 32% by γ-T and 27, 33, and 23% by α-T. ICAM expression was reduced by 14, 25 and 32% by γ-T and 25, 30 and 23% by α-T. Stimulation by IL-1β for 6h increased PGE2 and PGI2 production 10- and 4-fold, respectively. Basal PGE2 and PGI2 production was reduced by γ-T treatment at ≥40 μM compared to controls. γ-T caused a dose-dependent decrease in PGE2 and PGI2 production in IL-1-stimulated HAEC, but α-T increased PGE2 and PGI2 production in both stimulated and unstimulated HAEC. Our data suggest that uptake of γ-T by HAEC exceeded that of α-T, yet reduction of adhesion molecules by γ-T was similar to that by α-T. γ-T suppressed vasodilatory PG production, indicating a differential effect of γ-T and α-T on factors associated with vascular function.

Publication Title

FASEB Journal

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