Dose-Dependent Effects of EPA Supplementation on Plasma Specialized Pro-Resolving Mediators in Major Depressive Disorder Patients with Chronic Inflammation

Abstract

Abstract Objectives The immunomodulatory effects of eicosapentaenoic acid (EPA) support it as an effective treatment for major depressive disorder (MDD) associated with chronic inflammation. Increased production of specialized pro-resolving mediators (SPM) during EPA supplementation may help reduce inflammation. We compared the effects of different EPA doses on plasma fatty acids and SPM in MDD patients. Methods MDD patients with baseline inflammation (N = 61, IDS-C score >25; BMI > 25 kg/m2; serum CRP > 3 mg/L) were enrolled in a 2-site, 12-wk randomized trial comparing EPA 1, 2 and 4 g/d to placebo (soybean oil). Plasma fatty acids (mol%) and SPM (pg/mL) were measured at baseline and 12 wks (n = 8 [10], 12 [11], 11 and 10 in the placebo, EPA 1, 2 and 4 g/d arms, respectively). Dose effects were tested using the Kruskal-Wallis followed by pairwise Wilcoxon rank-sum tests with Benjamini-Hochberg correction. Results In the placebo arm, plasma EPA and EPA derivatives did not change at 12 wks, relative to baseline. EPA supplementation significantly increased plasma EPA dose-dependently (3-, 3- and 9-fold in the 1, 2 and 4 g/d arms). Similar significant dose-dependent increases in EPA derivatives were observed in the EPA arms, including 18-hydroxy-EPA (18-HEPE, 8-, 7- and 14-fold) and 15-HEPE (4-, 6- and 10-fold). The increase in 18-HEPE, a precursor of EPA-series resolvins (RvE), by 4 g/d EPA was significantly greater than with lower doses. While RvE1 remained undetected in all treatment arms, RvE2 was detected in some subjects at baseline and 12 wks with a dose-dependent median increase (+3, +6 and +8 pg/mL). RvE3, undetectable at baseline, became detectable in more subjects dose-dependently (n = 1, 2, 3 and 6). The reduction in plasma arachidonic acid (AA) by EPA supplementation significantly differed from placebo only at 2 and 4 g/d but not between the two doses. AA derivatives were not affected, except for the pro-resolving lipoxin B4, which was rarely detected at baseline, but became detectable in most subjects after EPA supplementation (median: 46, 59 and 94 pg/mL). Conclusions Our results show a robust dose-effect of EPA in increasing plasma EPA and EPA-derived 18-HEPE, which may result in improved conversion to RvE2 and RvE3. Its associations with reduced inflammation and improved IDS-C scores will be further analyzed. Funding Sources NCCIH.