Specific lipid mediator signatures of human phagocytes: microparticles stimulate macrophage efferocytosis and pro-resolving mediators.

Abstract

Phagocytes orchestrate acute inflammation and host defense. Here we carried out lipid mediator (LM) metabololipidomics profiling distinct phagocytes: neutrophils (PMN), apoptotic PMN, and macrophages. Efferocytosis increased specialized pro-resolving mediator (SPM) biosynthesis, including Resolvin D1 (RvD1), RvD2, and RvE2, which were further elevated by PMN microparticles. Apoptotic PMN gave elevated prostaglandin E(2), lipoxin B(4) and RvE2, whereas zymosan-stimulated PMN showed predominantly leukotriene B(4) and 20-OH-leukotriene B(4), as well as lipoxin marker 5,15-diHETE. Using deuterium-labeled precursors (d(8)-arachidonic acid, d(5)-eicosapentaenoic acid, and d(5)-docosahexaenoic acid), we found that apoptotic PMN and microparticles contributed to SPM biosynthesis during efferocytosis. M2 macrophages produced SPM including maresin-1 (299 ± 8 vs 45 ± 6 pg/2.5 × 10(5) cells; P < .01) and lower amounts of leukotriene B(4) and prostaglandin than M1. Apoptotic PMN uptake by both macrophage subtypes led to modulation of their LM profiles. Leukotriene B(4) was down-regulated in M2 (668 ± 81 vs 351 ± 39 pg/2.5 × 10(5) cells; P < .01), whereas SPM including lipoxin A(4) (977 ± 173 vs 675 ± 167 pg/2.5 × 10(5) cells; P < .05) were increased. Conversely, uptake of apoptotic PMN by M2 macrophages reduced (∼ 25%) overall LM. Together, these results establish LM signature profiles of human phagocytes and related subpopulations. Moreover, they provide evidence for microparticle regulation of specific endogenous LM during defined stages of the acute inflammatory process and their dynamic changes in human primary phagocytes.