Interleukin-1 Stimulates Arachidonic Acid 15-Hydroxylation in Human Endothelial Cells

lnterleukin-1 (IL-1 ) induces the expression of immediate-early gene encoding for cyclooxygenase in human endothelial cells (EC) [1], and so increases prostanoid production. However, the effect of IL-1 on the synthesis of monohydroxy fatty acids by these cells is still unknown. EC are able to synthesize 15- hydroxyeicosatetraenoic acid (15-HETE) from arachidonic acid (AA), and whether it is formed from the 15-lipoxygenase or the cyclooxygenase pathway still remains unclear. 15-HETE has no inflammatory activity, but it is capable of modulating the synthesis of other inflammatory eicosanoids [2–8]. The aim of this work was to examine whether IL-1 could regulate the synthesis of 15-HETE by human EC. We conclude that IL-1 increases 15-HETE production, and that this effect is mediated by an increase of the cyclooxygenase activity.