Endocrine Abstracts

Background: Pathological accumulation of intrahepatocellular triglyceride (IHTG) is the first stage non-alcoholic fatty liver disease (NAFLD), which encompasses a spectrum of disease from simple steatosis through to cirrhosis. Dietary interventions have demonstrated alterations in dietary fat quantity and quality affect IHTG content; diets rich in saturated compared to unsaturated fat increase IHTG accumulation to a greater extent. Studying the underlying mechanisms in vivo in humans remains challenging therefore, in vitro cellular models which recapitulate the effects of dietary alterations are needed for mechanistic insight.

Objective: To develop an in vitro cellular model to investigate dietary fatty acid (FA) composition influence on the development of IHTG accumulation as well as hepatocellular function and metabolism.

Methods: Human primary and Huh7 hepatocytes (maintained in human serum) were exposed to media enriched in unsaturated or saturated FAs at 200µM or 800µM for 7 days; both mediums contained 5.5 mM glucose. Cells and media were collected and cellular viability, FA storage, synthesis and secretion assessed.

Results: Although the IHTG composition of the Huh7 cells reflected the FA treatment, there were no notable differences in IHTG content between treatments, between respective FA concentrations. The FA treatment did not alter Huh7 cell viability but reduced de novo lipogenesis (DNL) was observed with increasing FA concentration for both FA compositions, with larger reductions for mediums with more unsaturated FAs at both concentrations. Primary human hepatocyte IHTG also reflected the media composition with similar changes in DNL to Huh7 cells when exposed to the respective FA compositions and concentrations. However, primary hepatocytes had poorer viability, greater variation (likely due to phenotype) and reduced TG secretion under all conditions, compared to Huh7 cells.

Conclusions: Observations suggest that compared to primary human hepatocytes, Huh7 cells are a useful model for investigating the effects of FA quality on the development of IHTG accumulation.