Polyunsaturated Fatty Acids and Modulation of Cholesterol Homeostasis in THP-1 Macrophage-Derived Foam Cells

Transformation of macrophages to foam cells is determined by the rates of cholesterol uptake and efflux. This study uses a real time RT-PCR technique to investigate the role of conjugated linoleic acid (CLA), α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) in the regulation of the ATP-binding cassette A1 (ABCA1) and liver X receptor α (LXR) genes, which are involved in cholesterol homeostasis. Accordingly, these fatty acids significantly reduced the total, free and esterified cholesterols within the foam cells. While the expression of the ABCA1 and LXRα genes was increased in the presence of the pharmacological LXRα ligand, T0901317, their mRNA expression was not significantly affected by CLA, ALA and EPA. These results suggest that although polyunsaturated fatty acids have an effect on cholesterol homeostasis, they cannot change the expression of the ABCA1 and LXRα genes. Alternatively, several other genes and proteins may be involved

Identification of potential serum biomarkers of inflammation and lipid modulation that are altered by fish oil supplementation in healthy volunteers

Long chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) lower risk of coronary heart disease (CHD), but mechanisms are not well understood. We used proteomics to identify human serum proteins that are altered by n-3 LCPUFA. Such proteins could identify pathways whereby they affect CHD. Eighty-one healthy volunteers entered a double blind randomised trial to receive 3.5 g of fish oil or 3.5 g of high oleic sunflower oil daily. Serum was collected before and after 6 wk of intervention. Serum was analysed by proteomics using 2-DE. Proteins that were differentially regulated were identified by MS. We also analysed serum apolipoprotein A1 (apo A1), high-density lipoprotein (HDL) particle size and haptoglobin. Serum levels of apo A1, apo L1, zinc-α-2-glycoprotein, haptoglobin precursor, α-1-antitrypsin precursor, antithrombin III-like protein, serum amyloid P component and haemopexin were significantly downregulated (all p<0.05) by fish oil compared with high oleic sunflower oil supplementation. Fish oil supplementation caused a significant shift towards the larger, more cholesterol-rich HDL2 particle. The alterations in serum proteins and HDL size imply that fish oil activates anti-inflammatory and lipid modulating mechanisms believed to impede the early onset of CHD. These proteins are potential diagnostic biomarkers to assess the mechanisms whereby fish oil protects against CHD in humans