Role of dextran sulfate in the catabolism of lipid emulsions

Abstract

Objective To investigate the effects of scavenger receptor A on the catabolism of lipid emulsions and further to see if it differently affects long-chain triglyceride (LCT) and fish oil (FO) emulsions. Methods A total of 24 C57BL/6J female mice, 10 to 12 weeks old, were randomly divided into 4 groups with 6 mice in each group. Two groups of mice were intravenously injected with dextran sulfate ( DexSO4 ) ( 1 mg/mouse) followed by intravenous injection of [1α, 2α(n)-3H] cholesteryl oleoyl ether [(3H)CEt] labelled LCT or FO emulsions (0.4mg triglycerde/mouse) at 2 minutes respectively, and other two groups were injected by saline as controls before injection of (3H)CEt labelled LCT and FO emulsions. Then, blood was drawn at fixed intervals to measure the radioactivities and the emulsion's fractional catabolic rates (FCR) were calculated. With the same procedures above mentioned, non-radiolabelled LCT and FO emulsions were intravenously injected to mice to determine liver uptake of lipid emulsions under electromicroscopy. Finally, THP1 cell line was used to examine the effects of DexSO4 on cell uptake of LCT and FO emulsions in vitro. Results Pre-injection of DexSO4 to mice decreased the FCR of both LCT and FO emulsions at 72.38％ and 47.38％ respectively, as compared to controls ( P =0.020 ). Electromicroscopy showed that pre-injection of DexS04 decreased the uptakes of LCT and FO emulsions by Kupffer cells and sinusoidal endothelial cells similarly. In hepatocytes, no lipid droplets existed in mice with LCT emulsion injection, whereas some lipid droplets were still shown in mice with FO emulsions but with less quantities compared to control mice.In vitro, addition of DexSO4 to medium decreased THP1 cell uptakes of LCT and FO emulsions ( P =0.003 and 0.008) by 30.74％ and 41.60％ respectively. However, no differences were found in the effects of DexS04 on cell uptakes between LCT and FO emulsions ( P =0.080). Conclusion Scavenger receptor A plays important roles in catabolism of lipid emulsions to some extent, and it's effects on FO emulsions may be less than LCT emulsions. Key words: Lipid emulsions; Dextran sulfate; Long-chain triglycerides; Fish oil