Lipoprotein secretion by intestinal Caco-2 cells is affected differently by trans and cis unsaturated fatty acids: effect of carbon chain length and position of the double bond.

The effects of trans fatty acids on intestinal lipoprotein secretion were determined in polarized Caco-2 cells. Palmitic acid (16:0), palmitoleic acid (c-16:1delta9), and palmitelaidic acid (t-16:1delta9), as well as stearic acid (18:0), oleic acid (c-18:1delta9), c-vaccenic acid (c-18:1delta11), elaidic acid (t-18:1delta9), and t-vaccenic acid (t-18:1delta11) were studied. Compared with 18:0 (control), c- and t-18:1delta9 increased triacylglycerol secretion (2.7- and 3.6-fold, respectively) as well as apolipoprotein (apo) B-48 and apo B-100 secretion (both 1.6-fold compared with 18:0); c- and t-18:1delta11 caused a modest 1.7-fold increase in triacylglycerol secretion with no significant effect on secretion of apo B. Thus, the position of the double bond in the 18:1 isomers, but not its geometrical configuration, affected lipoprotein secretion by Caco-2 cells. In contrast, the effects of the geometrical isomers (cis and trans) of C16 fatty acids were not comparable: t-16:1delta9 did not affect triacylglycerol and apo B secretion (compared with 16:0, as control) whereas c-16:1delta9 was a potent stimulator of secretion of triacylglycerol (2.4-fold higher than 16:0), apo B-48 (1.3-fold higher than 16:0), and apo B-100 (1.5-fold higher than 16:0). We conclude that the carbon chain length of fatty acids, as well as the position of double bonds and their stereochemical configuration, are important determinants of the unique effects of various species of dietary trans fatty acids on lipoprotein secretion and composition in Caco-2 cells.