Metabolic profiling of murine plasma reveals eicosapentaenoic acid metabolites protecting against endothelial activation and atherosclerosis

Background and Purpose Atherosclerosis results from a maladaptive inflammatory response initiated by the intramural retention of LDL in susceptible areas of the arterial vasculature. The ω-3 polyunsaturated fatty acids (ω-3) have protective effects in atherosclerosis; however, their molecular mechanism is still largely unknown. The present study used a metabolomic approach to reveal the atheroprotective metabolites of ω-3 and investigate the underlying mechanisms. Experimental Approach We evaluated the development of atherosclerosis in LDL receptor-deficient mice (LDLR−/−) fed a Western-type diet (WTD) plus ω-3 and also LDLR−/− and fat-1 transgenic (LDLR−/−-fat-1tg) mice fed a WTD. The profiles of ω-3 in the plasma were screened by LC–MS/MS using unbiased systematic metabolomics analysis. We also studied the effect of metabolites of eicosapentaenoic acid (EPA) on endothelial activation in vitro. Key Results The ω-3 diet and fat-1 transgene decreased monocyte infiltration, inhibited the expression of pro-inflammatory genes and significantly attenuated atherosclerotic plaque formation and enhanced plaque stability in LDLR−/− mice. The content of 18-hydroxy-eicosapentaenoic acid (18-HEPE) and 17,18-epoxy-eicosatetraenoic acid (17,18-EEQ), from the cytochrome P450 pathway of EPA, was significantly higher in plasma from both ω-3-treated LDLR−/− and LDLR−/−-fat-1tg mice as compared with WTD-fed LDLR−/− mice. In vitro in endothelial cells, 18-HEPE or 17,18-EEQ decreased inflammatory gene expression induced by TNFα via NF-κB signalling and thereby inhibited monocyte adhesion to endothelial cells. Conclusions and Implications EPA protected against the development of atherosclerosis in atheroprone mice via the metabolites 18-HEPE and/or 17,18-EEQ, which reduced endothelial activation. These compounds may have therapeutic implications in atherosclerosis.