ESPE Abstracts

Introduction: Obesity is among the most prevalent health problems and is associated with increased risk of various metabolic disorders, including type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). Fatty acids comprise a major part of the lipids and have remarkable effect on cell biology. Trans fatty acids (tFAs) are generally a by-product of manufacturing of fats. However, naturally-produced tFAs that are found in milk and dairy products, are suggested to be beneficial for health. Trans-palmitoleic acid (t-PA), a naturally occurring tFA has been shown to be related to better lipid profile including higher HDL-C and lower triglyceride (TG), and associated with decreased insulin resistance, lower metabolic risk and incident of type2 diabetes. Thus, the aim of this study was to investigate the effects of tPA on lipid accumulation in liver cells and the gene expression of fatty acid synthase (FAS) enzyme and the activity of peroxisome proliferator-activated receptor alpha (PPARα), an important nuclear receptor in the regulation of lipid metabolism.

Methods: HepG2 liver cells were cultured and treated with different concentrations of tPA and palimitic acid. Intracellular TG levels were evaluated by Oil red O staining of the cultured cells as well as extraction of cellular lipids and TG measurement with an enzymatic method. The expression of FAS gene was assessed by real-time PCR, after total RNA extraction and the synthesis of cDNA. The activity of PPARα was evaluated by luciferase reporter assay, via transfecting HEK293T cells with the vector comprising the PPARα response element.

Results: Both tPA and palmitic acid caused TG deposition in liver cells; however, the TG levels were significantly lower in cells treated with tPA compared with the cells that were treated with palmitic acid (P < 0.001). The gene expression of FAS was enhanced by both fatty acids, but in cells treated with tPA, it was significantly lower than palmitic acid (P < 0.001). Treatment of cells with tPA resulted in the activation of PPARα, especially at lower concentrations (P < 0.001), while palmitic acid did not have any effect on this nuclear receptor.

Conclusion: The results showed that less TG is accumulated in liver cells treated with tPA compared to palmitic acid which may be due to lower induction of FAS enzyme and activation of PPARα by tPA. Thus this fatty acid has better influence on liver cells compared to its saturated counterpart. Further clinical studies are suggested for assessment of the value of tPA as a beneficial supplement.