LAUSR

Type of funding sources: Private company. Main funding source(s): Amarin Pharmaceutical, Inc. Elucida Research LLC. Omega-3 fatty acid (n3-FA) treatment reduces cardiovascular (CV) risk in relation to circulating EPA/AA ratios. Treatment with icosapent ethyl (IPE), a highly purified EPA formulation, increased the EPA/AA ratio in treated patients (MARINE, ANCHOR). Unlike mixed n3-FA formulations, IPE reduced a composite of CV events in high-risk patients (REDUCE-IT) in relation to on-treatment EPA levels. These benefits of EPA may result in part from effects on vascular endothelial function and fatty acid content during inflammation. We measured the effect of EPA on human endothelial cells (HUVECs) during inflammatory activation, monitoring the release of soluble intercellular adhesion molecule-1 (sICAM-1) and changes in fatty acid content. HUVECs were challenged with IL-6 (12 ng/mL) for 2 hours and then treated with EPA (40 µM) or vehicle for 24 hours. Total protein content was measured in cell lysates. Total fatty acids were extracted and derivatized using methanol containing 14% boron trifluoride to form fatty acid methyl esters (FAME). Gas chromatography measured total fatty acid content from C14-C24 and normalized to total protein. Levels of sICAM-1 were measured in cell supernatant using immunochemistry. EPA treatment increased the EPA/AA ratio by >20-fold compared to IL-6 treatment alone (1.55 ± 0.11 vs. 0.07 ± 0.003, p<0.001). The increased EPA/AA ratio correlated with EPA and docosapentaenoic acid (DPA) levels in lysates, which increased by 19-fold (26.71 ± 1.28 vs. 1.28 ± 0.05 mg/g protein, p<0.001) and 4-fold (29.42 ± 1.91 vs. 6.17 ± 0.36 mg/g protein, p<0.001), respectively, compared to IL-6. While IL-6 treatment increased sICAM-1 release (83%, p<0.001), subsequent treatment with EPA reduced sICAM-1 release by 39% (p<0.001). In human ECs, EPA increased the EPA/AA ratio along with other n3-FAs under conditions of inflammation. Changes in the EPA/AA ratio correlated with reductions in sICAM-1 release with IL-6 exposure. As on-treatment EPA levels predict reduced CV risk, these direct vascular benefits of EPA may contribute to reduced CV risk observed in outcome trials.