Marine n-3 Fatty Acids and Vascular Disease: Solid Evidence in a Sea of Uncertainties

Omega-3 polyunsaturated fatty acids and pulmonary arterial hypertension: Insights and perspectives

Pulmonary arterial hypertension (PAH) is a rare and progressive disorder that affects the pulmonary vasculature. Although recent developments in pharmacotherapy have extended the life expectancy of PAH patients, their 5-year survival remains unacceptably low, underscoring the need for multitarget and more comprehensive approaches to managing the disease. This should incorporate not only medical, but also lifestyle interventions, including dietary changes and the use of nutraceutical support. Among these strategies, n-3 polyunsaturated fatty acids (n-3 PUFAs) are emerging as promising agents able to counteract the inflammatory component of PAH. In this narrative review, we aim at analysing the preclinical evidence for the impact of n-3 PUFAs on the pathogenesis and the course of PAH. Although evidence for the role of n-3 PUFAs deficiencies in the development and progression of PAH in humans is limited, preclinical studies suggest that these dietary components may influence several aspects of the pathobiology of PAH. Further clinical research should test the efficacy of n-3 PUFAs on top of approved clinical management. These studies will provide evidence on whether n-3 PUFAs can genuinely serve as a valuable tool to enhance the efficacy of pharmacotherapy in the treatment of PAH.

Protective activities of distinct omega-3 enriched oils are linked to their ability to upregulate specialized pro-resolving mediators

Clinical studies using a range of omega-3 supplements have yielded conflicting results on their efficacy to control inflammation. Omega-3 fatty acids are substrate for the formation of potent immune-protective mediators, termed as specialized pro-resolving mediators (SPM). Herein, we investigated whether observed differences in the potencies of distinct omega-3 supplements were linked with their ability to upregulate SPM formation. Using lipid mediator profiling we found that four commercially available supplements conferred a unique SPM signature profile to human macrophages, with the overall increases in SPM concentrations being different between the four supplements. These increases in SPM concentrations were linked with an upregulation of macrophage phagocytosis and a decreased uptake of oxidized low-density lipoproteins. Pharmacological inhibition of two key SPM biosynthetic enzymes 5-Lipoxygenase or 15-Lipoxygenase reversed the macrophage-directed actions of each of the omega-3 supplements. Furthermore, administration of the two supplements that most potently upregulated macrophage SPM formation and reprogrammed their responses in vitro, to APOE^-/- mice fed a western diet, increased plasma SPM concentrations and reduced vascular inflammation. Together these findings support the utility of SPM as potential prognostic markers in determining the utility of a given supplement to regulate macrophage responses and inflammation.

Lowering the linoleic acid to alpha-linoleic acid ratio decreases the production of inflammatory mediators by cultured human endothelial cells

Alpha-linolenic acid (ALA) and linoleic acid (LA) are precursors for longer-chain more unsaturated fatty acids and for lipid signalling molecules that may influence inflammatory processes through a variety of mechanisms. The actions of LA and ALA may be divergent and interdependent. The aim of this study was to investigate the incorporation and metabolism of ALA and LA in cultured in EA.hy926 endothelial cells and the production of inflammatory mediators (VEGF, RANTES, ICAM-1, MCP-1, IL-6 and IL-8) by these cells when exposed to different concentrations of ALA, LA and ratios of LA:ALA. Human endothelial cells were cultured with either culture medium or culture medium supplemented with ALA, LA or various ratios of LA:ALA (1:4, 1:1, 4:1, 9:1 or 19:1) followed by 24 h TNF-α stimulation; the total concentration of ALA plus LA was kept constant at 100 μM. The incorporation and metabolism of ALA and LA was measured using gas chromatography. The production of inflammatory mediators in the supernatant was assessed using a Luminex Multi-Analyte kit. Both ALA and LA were incorporated and metabolised by the endothelial cells. Cells incubated with ALA had a statistically significantly lower production of VEGF, RANTES, ICAM-1, MCP-1 and IL-6 compared to cells incubated without additional ALA. LA was not found to exert pro-inflammatory effects. Cells incubated with low LA:ALA ratios had lower production of VEGF, RANTES, MCP-1 and IL-6 when compared with a LA:ALA ratio of 19:1. These findings suggest that a low LA:ALA ratio exerts anti-inflammatory effects by lowering the production VEGF, RANTES, ICAM-1, MCP-1 and IL-6 in TNF-α stimulated endothelial cells compared to a high ratio. These effects were likely mediated by ALA, but LA may also possess some anti-inflammatory effects.