Comparing the lipogenic and cholesterolgenic effects of individual trans‐18:1 isomers in liver cells. Issue 3 (15th July 2016)

• Record Type: Journal Article
• Authors: Vahmani, Payam; Meadus, William J.; Duff, Pascale; Rolland, David C.; Dugan, Michael E. R.
• Is Part Of: European journal of lipid science and technology. Volume 119:Issue 3(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2016-07-15
• Subjects: Cell culture -- Cholesterol -- Liver -- Trans fatty acids; Oils and fats, Edible -- Periodicals; Lipids -- Periodicals; 660.63
• DOI: 10.1002/ejlt.201600162
• Languages: English
• ISSNs: 1438-7697

Abstract

Abstract : The present study compared the lipogenic/cholesterolgenic effects of t 6‐, t 9‐ (positive control), t 10‐, t 11‐, t 13‐, t 14‐, t 15‐18:1, cis ( c )9‐18:1 ( cis control) or bovine serum albumin (BSA; negative control) in liver cells (HepG2). Fatty acids (100 μM) were complexed to BSA, and cells were incubated for 24 h. Two wells of cells were cultured per treatment per experiment, and the experiment was repeated three times ( n = 6). The fatty acid treatments had no effect on cell viability compared to BSA. The content of triacylglycerol (TG) and cholesteryl esters (CE) were increased ( P < 0.05) when culturing with t 6‐, t 9‐, and t 10‐18:1 compared to BSA control, but were not affected ( P > 0.05) by other fatty acid treatments. Consistent with the effects on TG and CE, culturing cells with t 6‐, t 9‐, or t 10‐18:1 upregulated expression of several genes involved in fatty acid and cholesterol synthesis, and effects were most consistent for t 6‐18:1. Esterification of t 18:1 isomers into TG was 1.7‐fold greater when cells were cultured with t 6‐, t 9‐, and t 10‐18:1 compared to t 11‐, t 13‐, t 14‐, and t 15‐18:1. The results from the present study indicate t 6‐, t 9‐, and t 10‐18:1 induce lipogenic/cholesterolgenic gene expression resulting in increased cellular content of TG and CE, while t 11‐, t 13‐, t 14‐, and t 15‐18:1 responded similarly to c 9‐18:1 and control treatments. Practical application : Trans fatty acids have been associated with cardiovascular disease mainly through adverse effects on blood lipoprotein profiles. Several t 18:1 isomers are found in foods, but studies on individual isomers have been mostly limited to t 9‐ and t 11‐18:1. The isomer specific effects of other t 18:1 isomers have been limited because of their lack of commercial availability. To investigate the effects of individual t 18:1 isomers, we isolated and purified several isomers from beef fat using silver‐ion chromatography techniques. We examined the effects of seven t 18:1 isomers in liver cells on cellular triacylglycerol and cholesterol content, fatty acid composition, and expression of key genes involved in fatty acid and cholesterol syntheses. Our results indicate that the major t 18:1 isomers found in partially hydrogenated vegetable oils, and ruminant fats when feeding grain based diets (i.e., t 6‐ to t 10‐18:1) have more potent lipogenic/cholesterolgenic effects compared to isomers enriched in ruminant fats when feeding forage based diets (i.e., t 11‐ to t 15‐18:1). The major trans ( t )18:1 isomers found in partially hydrogenated vegetable oils, and ruminant fats when feeding grain based diets (i.e., t 6‐ to t 10‐18:1) induced lipogenic/cholesterolgenic gene expression in liver cells resulting in increased cellular content of triacylglycerol and cholesteryl esters. In contrast, t ‐18:1 isomers enriched in ruminant fats when feeding forage based diets (i.e., t 11‐ to t 15‐18:1) responded similarly to cis 9‐18:1 and control treatments. Abstract : The major trans ( t )18:1 isomers found in partially hydrogenated vegetable oils, and ruminant fats when feeding grain based diets (i.e., t 6‐ to t 10‐18:1) induced lipogenic/cholesterolgenic gene expression in liver cells resulting in increased cellular content of triacylglycerol and cholesteryl esters. In contrast, t ‐18:1 isomers enriched in ruminant fats when feeding forage based diets (i.e., t 11‐ to t 15‐18:1) responded similarly to cis 9‐18:1 and control treatments.