Impact of oxidized phosphatidylcholine supplementation on the lipidome of RAW264.7 macrophages

Oxidized phospholipids (OxPLs) have emerged as critical damage-associated molecular patterns (DAMPs) and modulators of numerous biological processes, including inflammation, playing a significant role in health and disease. Despite their recognized influence on macrophage polarization, the precise mechanisms by which distinct OxPL species shape macrophage behavior remains poorly understood. The present study investigates the impact of two oxidized phosphatidylcholines (OxPC): omega 3 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphatidylcholine (OxPC22:6), and omega 6 1-stearoyl-2-linoleoyl-sn-glycero-3-phosphatidylcholine (OxPC18:2), on the lipidomic profile of RAW264.7 macrophages, through an LC-MS lipidomic analysis. Our findings demonstrate that the OxPCs under study modulate macrophage lipidome differently, highlighting the significance of the sn-2 acyl chain composition for their biological function. When administered alone, neither of the OxPCs induced a pro-inflammatory phenotype in macrophages. OxPC22:6 appears to induce a preparatory pro-inflammatory state in macrophages, improving their subsequent inflammatory responses, while OxPC18:2 seems to induce a resting state on macrophages. Under LPS stimulation, both OxPCs were found to selectively attenuate certain LPS-driven lipidomic changes (PC.O, PC.P, PI.P, PE.P) while amplifying others (DG, Cer, LPC, PE.O, PI.O, TG, PC, PI) and introducing unique alterations to the macrophage lipidome (SM, PE, LPE). Core lipidomic changes, crucial for macrophages' LPS response, were identified, with sustained elevation of TG, DG, Cer, PC, LPC, and PI.O and reduction of PE.O, PI, and CAR. These observations suggest that, in the presence of LPS, mainly OxPC22:6 amplifies the pro-inflammatory lipidomic signature of macrophages. Further research is needed to clarify whether the observed lipidomic adaptations improve, impair, or inhibit macrophages' inflammatory capacities and response.