13-hydroxy octadecadienoic acid (13-HODE) inhibits triacylglycerol-rich lipoprotein secretion by CaCo-2 cells

Oxidized lipids present in atherogenic lipoproteins are derived, in part, from the diet. To address the effects of an oxidized lipid on intestinal lipoprotein assembly and secretion, CaCo-2 cells were incubated with 13-HODE or its native fatty acid, linoleic acid, and triacylglycerol-rich lipoprotein synthesis and secretion were investigated. 13-HODE was readily taken up by cells and esterified to lipids. Although both fatty acids were largely esterified to neutral lipids, in comparison to neutral lipids containing linoleic acid, a greater proportion of cellular neutral lipids containing 13-HODE and/or its metabolites was secreted. Compared to linoleic acid, however, 13-HODE caused less triacylglycerol, derived from de novo synthesis, and less triacylglycerol mass to be secreted. Cells incubated with both linoleic acid and 13-HODE together secreted less triacylglycerol mass than did cells incubated with linoleic acid alone. Less newly synthesized apoB and apoB mass were secreted by cells incubated with 13-HODE without altering the abundance of apoB mRNA. The fraction of newly synthesized apoB translocated into the secretory pathway of cells exposed to 13-HODE was significantly 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.