Abstract 13683: Eicosapentaenoic Acid (EPA) Decreases Endothelin Converting Enzyme-1 Expression and Improves Nitric Oxide Release in Pulmonary Endothelium Following Challenge With Air Pollutants

Abstract

Background: Air pollution particulate matter (PM) contributes to global mortality and chronic conditions, especially cardiovascular (CV) disease. Exposure to PM and cytokines like IL-6 cause endothelial cell (EC) dysfunction, leading to nitric oxide synthase (eNOS) uncoupling. The omega-3 fatty acid EPA improves eNOS coupling and reduces vascular inflammation. REDUCE-IT showed that treatment with icosapent ethyl (IPE), a purified EPA ethyl ester, reduced composite CV events. We compared the effects of EPA on pulmonary EC (PEC) function and protein expression following challenge with PMs versus IL-6. Methods: PECs were treated with EPA (40 μM) or equivolume vehicle for 2 h and then challenged with IL-6 (12 ng/mL) or PM (50 μg/mL) collected from urban environments (“urban PM”) for up to 8 h. Proteomic analysis was performed using LC/MS to measure relative protein expression. Significant ( p <0.05) changes between treatment groups (>1-fold) were analyzed by bioinformatic packages. Biological pathways were analyzed by gene set enrichment analysis (GSEA). In parallel, cells were stimulated with calcium ionophore to elicit nitric oxide (NO) and peroxynitrite (ONOO – ) release as assayed by tandem porphyrinic nanosensors; the NO/ONOO – ratio indicates eNOS coupling efficiency. Results: Challenge with IL-6 and urban PM caused eNOS uncoupling as evidenced by a decreased NO/ONOO – ratio of 35% (1.43 ± 0.04 vs. 2.19 ± 0.02, p <0.001) and 50% (1.22 ± 0.07 vs. 2.42 ± 0.15 , p <0.001), respectively, compared to control. EPA increased the NO/ONOO – ratio relative to both IL-6 (39%; 1.99 ± 0.11, p <0.001) and urban PM (39%; 1.69 ± 0.14 , p <0.05). Proteomics revealed that EPA decreased expression of endothelin converting enzyme-1 (ECE1) relative to both IL-6 (1.2-fold, p = 0.017) and urban PM (1.1-fold, p = 0.045). GSEA showed significant modulations to 18 and 35 proteins within the neutrophil degranulation pathway (GO:0043312) with EPA treatment relative to IL-6 and urban PM ( p <0.0001 in both comparisons). Conclusion: EPA favorably reversed EC dysfunction and expression of inflammatory proteins and pathways following challenge with air pollution PMs similar to IL-6. These broad anti-inflammatory actions may contribute to reduced CV risk with EPA as observed in outcome trials.