Interleukin-1 Enhances the Ability of Cultured Human Umbilical Vein Endothelial Cells to Oxidize Linoleic Acid

• Published in: The Journal of biological chemistry 1995-07, Vol.270 (29), p.17279-17286
• Main Authors: Camacho, Mercedes, Godessart, Nuria, Antón, Rosa, García, Montserrat, Vila, Lus
• Format: Article
• Language: English
• Subjects: Cells, Cultured; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Humans; Interleukin-1 - pharmacology; Isoenzymes - metabolism; Linoleic Acid; Linoleic Acids - metabolism; Oxidation-Reduction; Prostaglandin-Endoperoxide Synthases - metabolism; Umbilical Veins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.29.17279

Human umbilical vein endothelial cells (HUVEC) were treated with recombinant interleukin (IL)-1β, and the metabolism of exogenous linoleic acid was studied. High performance liquid chromatography, gas chromatography-mass spectrometry, and chiral analysis revealed that HUVEC enzymatically convert linoleic acid mainly into 13-(S)hydroxy-9(Z),11(E)-octadecadienoic (13-HODE) and 9-(R)hydroxy-10(E),12(Z)-octadecadienoic acids, which may isomerize toward all-trans compounds. IL-1β increased the formation of all octadecanoids in a time- and dose-dependent manner with similar EC50 (approximately 1 unit/ml). The apparent Km values of linoleic acid were 15.59 ± 8.39 and 152.9 ± 84 μM (p < 0.05) in IL-1β-treated cells and controls, respectively, indicating a higher substrate affinity in cells stimulated with IL-1β. Ratios of S/R enantiomers for the hydroxyoctadecanoids produced by untreated and IL-1β-treated cells were similar to those from isolated cyclooxygenases (COXs), whereas isolated 15-lipoxygenase yielded 13-HODE with a strict S configuration. The formation of octadecanoids was inhibited in a dose-dependent manner by several COX inhibitors in both controls and IL-1β-treated cells, COX2 selective inhibitors being more effective on IL-1β-treated cells than on controls. COX1 and COX2 protein levels increased less than 2-fold and 8-fold, respectively, after IL-1β treatment. The specificity of COX inhibitors was proven since they did not inhibit 13-HODE formation by human polymorphonuclear leukocytes. Overall, these results indicate that COXs are responsible for the oxidative metabolism of linoleic acid in HUVEC, and IL-1β increases it by inducing the expression of new enzyme, mainly COX2.