Resolvins D1, D2, and other mediators of self-limited resolution of inflammation in human blood following n-3 fatty acid supplementation.

BACKGROUND Resolvins and protectins are families of local lipid mediators generated from the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) during self-limited resolution of inflammation. We aimed to develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to measure these lipid mediators in human blood following n-3 fatty acid supplementation and to determine whether the blood collection method affects their measured concentration. METHODS Blood samples from 20 healthy volunteers enrolled in an n-3 fatty acid supplementation trial were collected in EDTA, heparin, or citrate, or prepared as serum after volunteers had undergone 3 weeks of supplementation. Plasma or serum was purified by solid-phase chromatography and analyzed with LC-MS/MS. RESULTS The assay identified 18R/S-hydroxy-5Z,8Z,11Z,14Z,16E-eicosapentaenoic acid (18R/S-HEPE); 17S-hydroxy-4Z,7Z,10Z,13Z,15E,19Z-docosahexaenoic acid (17R/S-HDHA); 7S,8R,17S-trihydroxy-4Z,9E,11E,13Z,15E,19Z-docosahexaenoic acid (RvD1); 7S,8R,17R-trihydroxy-4Z,9E,11E,13Z,15E19Z-docosahexaenoicacid (17R-RvD1); 7S,16R,17S-trihydroxy-4Z,8E,10Z,12E,14E,19Z-docosahexaenoic acid (RvD2); 10S,17S-dihydroxy-4Z,7Z,11E,13Z,15E,19Z-docosahexaenoicacid (10S,17S-DiHDHA); and 10R,17S-dihydroxy-4Z,7Z,11E,13E,15Z,19Z-docosahexaenoic acid (protectin D1, PD1). The limits of detection and quantification were 3 pg and 6 pg on-column, respectively. The pathway precursors 18R/S-HEPE and 17R/S-HDHA, but not the resolvins, were lower in serum compared with plasma. After n-3 fatty acid supplementation, mean (SD) EDTA plasma concentrations were: 18R/S-HEPE 386 (56) pg/mL, 17R/S-HDHA 365 (65) pg/mL, RvD2 26 (4) pg/mL, RvD1 31 (5) pg/mL, and 17R-RvD 161 (7) pg/mL. 10S,17S-DiHDHA and PD1 concentrations were below the limit of quantification. CONCLUSIONS This is the first study reporting 17R/S-HDHA, RvD1, and RvD2 concentrations measured in human blood following oral n-3 fatty acid supplementation. The concentrations of the antiinflammatory lipid mediators RvD1 and RvD2 were within the biological range known to have antiinflammatory and proresolving activities in isolated human leukocytes and in in vivo studies in mice.