Lipoxygenase expression and oxylipin analysis in human THP-1 monocyte-derived macrophages

Abstract

Macrophages are homeostatic cells with remarkable phenotypic plasticity and key roles in inflammation. Macrophage lipoxygenases (LOX) oxygenate polyunsaturated fatty acids, producing oxylipins that are involved in inflammatory processes. Most insights into human LOX products and their roles in inflammation have been gained from animal models and human peripheral blood monocyte-derived macrophages (PB-MDMs). Human macrophage cell lines, although less explored, offer potential advantages due to their reduced culture complexity and variability. This study analyzes LOXes of human THP-1 monocyte-derived macrophages (THP-MDMs). LPS-polarized and IL-4-polarized macrophages (M_LPS and M_IL4) from THP-MDMs expressed the same LOX isoforms as polarized PB-MDMs. In both models, 5-LOX was similarly expressed in M_LPS and M_IL4, whereas 5-LOX activating protein was higher in M_LPS. In contrast, 15-LOX1 and 15-LOX2 were predominantly expressed in M_IL4. HPLC-MS/MS oxylipin analysis revealed that M_IL4 from THP-MDMs and PB-MDMs produces similar metabolites of arachidonic, linoleic, eicosapentaenoic, and docosahexaenoic acids, including prostanoids, LOX, and cytochrome P450 monohydroxylated intermediates. Although precursors considered markers for resolvins and maresins pathways were identified, specialized pro-resolving mediators (SPMs) were not detected. These findings highlight the structural and functional similarities between PB-MDMs and THP-MDMs, positioning THP-MDMs as a promising model for studying macrophage LOX and oxylipin biosynthesis.