Potentiation of polyunsaturated fatty acids anti-inflammatory action through redox signaling in fructose-treated endothelial cells

Abstract

Fructose intake is associated with low-grade inflammation and increased oxidative stress. Among long chain polyunsaturated fatty acids (LC-PUFAs), Ω-6 are recognized as a contributing factor to inflammation, while Ω-3 LC-PUFAs are considered as functional foods with beneficial effects, including inhibition of pro-inflammatory pathways. The aim of this study was to analyze combined effects of physiologically relevant LC-PUFAs and fructose on inflammation and antioxidant enzymes in the in vitro model of vascular endothelial cells. We examined the effects of 0.5 mM fructose, alone and in combination with Ω-6 (arachidonic (AA) and linoleic (LA)) and Ω-3 (eicosapentaenoic (EPA) and docosahexaenoic acid (DHA)) LC-PUFAs on expression of pro- inflammatory cytokines (tumor necrosis factor α (TNFα) and interleukin 6 (IL6)) in EA.hy926 cells. The protein levels of nuclear factor-κB (NF-κB) and IB, as well as its phosphorylation, together with superoxide dismutase (SOD) 1 and 2, catalase and glutathione reductase (GR) were also analyzed. Total ROS amounts were determined using flow cytometric analysis of cells stained with redox sensitive dihydrorhodamine 123 dye. The results showed that treatment of cells with fructose increased TNFα and decreased IL6 mRNA levels. Additional treatment with LA, DHA and EPA reduced TNFα and led to further decrease of IL6 expression. The observed changes were not associated with NFB activation. All examined enzymes were unchanged after fructose treatment, while GR was increased by LC-PUFA addition. SOD2 was reduced in cells treated with AA, LA and EPA, while increased ROS amounts were observed with AA, DHA and EPA. This was also evident in combined treatment with fructose. These preliminary results suggest that LC-PUFAs, besides effect on pro-inflammatory cytokines, reduce SOD2 levels and increase ROS. The increased levels of ROS could stimulate production of PUFA-derived peroxides, which in GSH-enriched environment might be converted into anti-inflammatory derivatives, additionally suppressing inflammation in fructose treated endothelial cells