Dynamics of DHA and EPA supplementation: incorporation into equine plasma, synovial fluid, and surfactant glycerophosphocholines

Introduction: Horses with asthma or osteoarthritis frequently receive ω-3 fatty acid supplements. Docosahexaenoic (DHA; 22:6) and eicosapentaenoic (EPA; 20:5) acids are essential ω-3 fatty acid precursors of anti-inflammatory mediators and components of structural glycerophospholipids (GPL) that act as reservoirs of these fatty acids. Analysis of the incorporation of dietary DHA + EPA into GPL pools in different body compartments has not been undertaken in horses. Objectives: We undertook a detailed study of dietary supplementation with DHA + EPA in horses and monitored incorporation into DHA- and EPA-containing glycerophosphocholines (GPC) 38:5, 38:6, 40:5, and 40:6 in plasma, synovial fluid (SF), and surfactant. Methods: Horses (n = 20) were randomly assigned to the supplement or control group and evaluated on days 0, 30, 60, and 90. GPC in plasma, SF, and surfactant were measured by high-resolution mass spectrometry with less than 3 ppm mass error. Validation of DHA and EPA incorporation into these GPC was conducted utilizing MS of the [M + Cl] adducts of GPC. Results: Dietary supplementation resulted in augmented levels of GPC 38:5, 38:6, 40:5, and 40:6 in all compartments. Maximum incorporation into GPCs was delayed until 60 days. Significant increases in the levels of GPC 38:5, 40:5, and 40:6, containing docosapentaenoic acid (DPA; 22:5), also was noted. Conclusions: DHA and EPA supplementation results in augmented storage pools of ω-3 essential fatty acids in SF and surfactant GPC. This has the potential to improve the ability of anti-inflammatory mechanisms to resolve inflammatory pathways in these critical compartments involved in arthritis and asthma.