Effects of aldehydes on CD36 expression

Introduction: During the oil frying process lipid peroxidation compounds are formed. These products can modulate gene expression and alter cellular behaviour. The cellular uptake of oxidized LDL, a key step in the development of atherosclerosis, is mediated by the CD36 scavenger receptor, whose expression is down-regulated by α-tocopherol.

Objective: To determine the effects of water-soluble aldehydes, obtained from thermally oxidized sunflower oil on the expression of CD36 scavenger receptor in human monocytes (THP-1 cells). We also wanted to study the effects of α-tocopherol on CD36 expression in the presence of water-soluble aldehydes.

Materials and Methods: Sunflower oil was heated in a frying pan, at 180–200°C for 40?min, water-soluble aldehydes were isolated, and the content of thiobarbituric acid reacting substances (TBARS) was determined. THP-1 monocytes were cultured in RPMI medium during 24?h and incubated with increasing concentrations of the water-soluble aldehydes (ranging from 0.05 to 1?μM) and with or without 50?μM of α-tocopherol. In parallel, THP-1 cells were cultured with the same volume of an extract obtained from non-oxidized oil or distilled water. The CD36 expression at the cell surface was studied with fluorescence-activated cell sorting (FACS).

Results: Monocytes incubated in a medium containing water-soluble aldehydes, showed a dose dependent increase in the expression of the CD36 protein on the cell surface, compared to with the control groups. When the cells were treated simultaneously with 50?μM of α-tocopherol a significant reduction in the expression of the CD36 protein was observed.

Conclusion: Water-soluble aldehydes, extracted from thermally oxidized culinary oil, increase the expression of CD36. This effect is partially decreased by the presence of α-tocopherol.