13-HYDROXY OCTADECADIENOIC ACID (13-MODE) INHIBITS TRIACYLGLYCEROL-RICH LIPOPROTEIN SECRETION BY CACO-2 CELLS

Oxidized lipids present in atherogenic lipoproteins are derived, in pa rt, from the diet. To address the effects of an oxidized lipid on inte stinal lipoprotein assembly and secretion, CaCo-2 cells were incubated with 13-HODE or its native fatty acid, linoleic acid, and triacylglyc erol-rich lipoprotein synthesis and secretion were investigated, 13-HO DE was readily taken up by cells and esterified to lipids. Although bo th fatty acids were largely esterified to neutral lipids, in compariso n to neutral lipids containing linoleic acid, a greater proportion of cellular neutral lipids containing 13-MODE and/or its metabolites was secreted, Compared to linoleic acid, however, 13-MODE caused less tria cylglycerol, derived from de novo synthesis, and less triacylglycerol mass to be secreted. Cells incubated with both linoleic acid and 13-MO DE together secreted less triacylglycerol mass than did cells incubate d with linoleic acid alone. Less newly synthesized apoB and apoB mass were secreted by cells incubated with 13-MODE without altering the abu ndance of apoB mRNA. The fraction of newly synthesized apoB translocat ed into the secretory pathway of cells exposed to 13-HODE was signific antly less than that observed in cells incubated with linolenic acid, suggesting that 13-HODE interfered with the assembly and secretion of triacylglycerol-rich lipoprotein particles.