Phosphatidylethanolamine species with n-3 and n-6 fatty acids modulate macrophage lipidome and attenuate responses to LPS stimulation

Phospholipids are increasingly recognized as key regulators of biological processes, including macrophage polarization and function. Among these, phosphatidylethanolamine (PE), a major constituent of cell membranes, is pivotal in maintaining cellular structure and function, yet the mechanisms through which native PE species influence macrophage immunometabolism remain largely unexplored. This study investigates the effects of two native PE species, PE 18:0/22:6 and PE 18:0/20:4, on the lipidome of resting and LPS-activated macrophages. Using C18 HPLC-MS/MS, we identified 337 lipid molecular species across 15 lipid subclasses, 332 of which varied significantly among conditions. Both PE 18:0/22:6 and PE 18:0/20:4 supplementation modulated the macrophage lipidome without inducing a pro-inflammatory phenotype under basal conditions. Notably, supplementation with PE 18:0/22:6 and PE 18:0/20:4 significantly increased lipid classes such as PE, PE O-, SM, CL, PG, LPE and PS, producing unique lipid profiles. Pre-treatment with PE 18:0/22:6 and PE 18:0/20:4 partially attenuated LPS-induced lipidomic changes, significantly reducing lipid classes like PC, including PC O- and PC P-, and Cer, which are typically linked to inflammation. While PE 18:0/20:4, from an individual lipid species perspective, may promote certain lipid profiles compatible with pro-inflammatory signaling pathways, particularly under inflammatory conditions, PE 18:0/22:6 seems to foster a lipid profile more supportive of inflammation resolution. This behaviour of PE 18:0/22:6 and PE 18:0/20:4 highlights the intricate complexity of lipid-mediated immunomodulation and emphasizes the critical role of cellular context in determining the functional outcomes of phospholipid supplementation in macrophage lipid metabolism and immune responses.