Olive oil and high-oleic sunflower oil on human plasma and erythrocyte membrane lipids

Triacylglycerol-rich lipoproteins interact with human vascular cells in a lipid-dependent fashion

Plasma triacylglycerol-rich lipoproteins (TRL) are being considered as a key lipid fraction in the pathogenesis of atherosclerotic cardiovascular disease. Here we compared the influence of two monounsaturated oils [virgin olive oil (VOO) and high-oleic sunflower oil (HOSO)] on the capability of postprandial TRL to interact with two human vascular cell lines [umbilical vein endothelial (HUVEC) and aorta smooth muscle (HASMC) cells]. A fluorescent probe was used for labeling TRL and to determine receptor activity of HUVEC and HASMC. The values for total cell-associated, bound, and internalized TRL were higher in HUVEC, and TRL from VOO was the better ligand recognized but at lower affinity than TRL from HOSO. There was a competitive effect of very low density lipoproteins (VLDL) for the uptake of TRL by cells, which was found to be dependent on the origin/lipid composition of the ligands and cell-type specific. We also conclude that the VLDL receptor (VLDLr) may contribute significantly to the HASMC binding capacity for postprandial TRL mediated by lipoprotein lipase (LPL) or LPL-binding molecules. Our findings are compatible with a selective role of the clustered O-linked sugar domain of the VLDLr in the catabolism of TRL by human vascular cells.

Postprandial triacylglycerols from dietary virgin olive oil are selectively cleared in humans

The aims of the present study were to evaluate the effect of a meal rich in virgin olive oil on triacylglycerol composition of human postprandial triacylglycerol-rich lipoproteins (fraction Sf > 400), and to assess the role of the triacylglycerol molecular species concentration and polarity on lipoprotein clearance. Fasting (0 h) and postprandial blood samples were collected hourly for 7 h from eight healthy normolipidemic subjects after the ingestion of the meal. Plasma and lipoprotein triacylglycerol concentrations increased quickly over fasting values and peaked twice at 2 and 6 h during the 7-h postprandial period. The triacylglycerols in the lipoprotein fraction at 2 h generally reflected the composition of the olive oil, however, the proportions of the individualmolecular species were altered by the processes leading to their formation. Among the major triacylglycerols, the proportion of triolein (OOO; 43.6%) decreased (P < 0.05), palmitoyl-dioleoyl-glycerol (POO; 31. 1%) and stearoyl-dioleoyl-glycerol (SOO; 2.1%) were maintained and linoleoyl-dioleoyl-glycerol (LOO; 11.4%) and palmitoyl-oleoyl-linoleoyl-glycerol (POL; 4.6%) significantly increased (P < 0.05) compared with the composition of the triacylglycerols in the olive oil. Smaller amounts of endogenous triacylglycerol (0.8%), mainly constituted of the saturated myristic (14:0)and palmitic (16:0) fatty acids, were also identified. Analysis of total fatty acids suggested the presence of molecular species composed of long-chain polyunsaturated fatty acids of the (n-3) family, docosapentaenoic acid, [22:5(n-3)] and docosahexaenoic acid (DHA), [22:6(n-3)] and of the (n-6) family [arachidonic acid, [20:4(n-6)]. The fastest conversion of lipoproteins to remnants occurred from 2 to 4 h and was directly related to the concentration of the triacylglycerols in the lipoprotein particle (r = 0.9969, P < 0.05) and not with its polarity (r = 0.1769, P > 0.05). The rates of clearance were significantly different among the major triacylglycerols (OOO, POO, OOL and POL) (P < 0.05) and among the latter ones and PLL (palmitoyl-dilinoleoyl-glycerol, POS (palmitoyl-oleoyl-stearoyl-glycerol) and OLL (oleoyl-dilinoleoyl-glycerol) (P < 0.01). OOO was removed faster and was followed by POO, OOL, POL, PPO (dipalmitoyl-oleoyl-glycerol), SOO, PLL, POS and OLL.