Effect of vitamin E on linoleic acid-mediated induction of peroxisomal enzymes in cultured porcine endothelial cells

Linoleic acid decreases endothelial barrier function in culture. We hypothesize that the mechanism may involve induction of peroxisomes, with subsequent generation of hydrogen peroxide, and that vitamin E may protect against barrier function loss by preventing the induction of peroxisomal enzymes. To investigate this hypothesis, we exposed cultured endothelial cells to 0 or 90 μmol/L linoleic acid [18:2(n-6)], with or without 25 μmol/L supplemental vitamin E, for 5 d. The induction of peroxisomes by linoleic acid exposure was determined by measuring cellular peroxisomal β-oxidation and catalase activity. Vitamin E alone had no effect on β-oxidation or catalase activity, whereas linoleic acid exposure significantly increased both compared with control values. Vitamin E supplementation prevented induction of peroxisomal β-oxidation and catalase activity by 18:2. In contrast, cell enrichment with vitamin E had no effect on 18:2-induced accumulation of cytoplasmic lipid-like droplets. These results confirm our hypothesis that the protective effects of vitamin E against fatty acid-mediated endothelial cell injury may be due in part to the ability of vitamin E to prevent the induction of peroxisomal β-oxidation enzymes and thus the formation of excess hydrogen peroxide.