August 24, 2021Open Access
Omega-3 and omega-6 fatty acids have distinct effects on endothelial fatty acid content and nitric oxide bioavailability
Key Result
EPA treatment of endothelial cells caused the greatest nitric oxide release (18% increase, p<0.001) and reduction in peroxynitrite (13%, p<0.05) compared to control, unlike DHA or AA.
Structured PICO
Does pretreatment with EPA, DHA, or AA improve nitric oxide bioavailability and alter fatty acid composition in human umbilical vein endothelial cells?
P
Population
Human umbilical vein endothelial cells (HUVECs) stimulated with calcium ionophore
I
Intervention
Pretreatment with eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or arachidonic acid (AA) at 10 µM
C
Comparator
Control/vehicle
O
Outcome
Bioavailability of nitric oxide (NO) and peroxynitrite (ONOO−), and fatty acid compositionsurrogate
EPA preferentially improves endothelial function by increasing nitric oxide bioavailability and reducing peroxynitrite compared to DHA and AA in vitro, providing mechanistic insight into the clinical benefits seen in the REDUCE-IT trial.
Main Result
Effect estimate: 18% increase in NO, 13% reduction in ONOO-
p-value: p=<0.001
Abstract
Treatment with high dose icosapent ethyl (IPE), an ethyl ester of the omega-3 fatty acid eicosapentaenoic acid (EPA), significantly reduced ischemic events in patients with either cardiovascular disease (CV) or diabetes plus other risk factors (REDUCE-IT) but the mechanism is not well understood. We compared the effects of EPA, docosahexaenoic acid (DHA), and the omega-6 fatty acid arachidonic acid (AA) on bioavailability of nitric oxide (NO) and fatty acid composition. Human umbilical vein endothelial cells (HUVECs) were pretreated with EPA, DHA, or AA (10 µM). Cells were stimulated with calcium ionophore and NO and peroxynitrite (ONOO−) were measured using porphyrinic nanosensors. Levels of EPA, DHA, AA and other fatty acids were measured by gas chromatography (GC). EPA treatment caused the greatest NO release (18%, p < 0.001) and reduction in ONOO− (13%, p < 0.05) compared to control; the NO/ ONOO− ratio increased by 35% (p < 0.001). DHA treatment increased NO levels by 12% (p < 0.01) but had no effect on ONOO− release. AA did not affect either NO or ONOO− release. Fatty acid treatments increased their respective levels in endothelial cells. EPA levels increased 10-fold to 4.59 mg/g protein (p < 0.001) with EPA treatment and the EPA/AA ratio increased by 10-fold (p < 0.001) compared to vehicle. Only EPA increased docosapentaenoic acid (DPA, omega-3) levels by 2-fold (p < 0.001). AA alone decreased the EPA/AA ratio 4-fold (p<0.001). These findings support a preferential benefit of EPA on endothelial function and omega-3 fatty acid content.