The effect of high density lipoprotein subfractions on endothelial eicosanoid secretion

Epidemiological, clinical, and experimental studies have demonstrated that high density lipoproteins (HDL) are protective against atherosclerosis. However, the respective influence of two main HDL subfractions (HDL2 and HDL3) on atherosclerosis process is not yet clear. The present study was designed to determine, which HDL subfraction was antiatherogenic in terms of eicosanoid release by human umbilical vein endothelial cells (HUVEC). Endothelial cells were incubated for 4 hours with HDL2 or HDL3 and prostaglandins 6-keto-PGF1alpha, thromboxane B2 and prostaglandin E2 were measured by RIA in culture supernatant. HDL2 has a dose dependent stimulatory effect on 6-keto-PGF1alpha release without stimulatory effect on thromboxane B2 secretion. The 6-keto-PGF1alpha/thromboxane B2 ratio increased progressively from 1.65 to 4.65 for 0.39 to 6.25 mg HDL protein/ml. The pattern of prostanoid secretion under influence of HDL3 showed a predominant response in 6-keto-PGF1alpha and TxB2 release. As regards PGE2, both HDL subfractions stimulated considerably secretion of this prostanoid in a dose dependent manner. In terms of PGI2/TxA2 balance the better antiatherogenic effect was observed with HDL2 subfraction.