Metabolization of Resolvin E4 by ω-Oxidation in Human Neutrophils: Synthesis and Biological Evaluation of 20-Hydroxy-Resolvin E4 (20-OH-RvE4)

Abstract

Resolvin E4 (RvE4) belongs to the resolvin family of specialized pro-resolving mediators (SPMs). The resolvins are endogenously formed mediators with both potent pro-resolving and anti-inflammatory biological activities and have attracted considerable attention in both inflammation research and drug discovery. Hence, further metabolism of the resolvins is of interest. Gaining knowledge about the structure–function of further metabolites of the resolvins is important due to their interest in drug-discovery efforts. For the first time, the total synthesis and biological evaluations of the ω-20 hydroxylated metabolite of RvE4, named herein 20-OH-RvE4, are presented. RvE4 was converted to 20-OH-RvE4 by human polymorphonuclear leukocytes. LC–MS/MS analysis and UV spectrophotometry reveal that the synthetic 20-OH-RvE4 matched RvE4-converted product 20-OH-RvE4 by human neutrophils. Cellular studies have revealed that RvE4 is formed from eicosapentaenoic acid in physiologic hypoxia by human neutrophils and macrophages, and we herein established that 20-OH-RvE4 is a secondary metabolite formed by the ω-oxidation of RvE4 in human neutrophils. A direct comparison of the biological actions between RvE4 and its metabolic product suggested that 20-OH-RvE4 displayed reduced bioactions in stimulating the efferocytosis of human senescent erythrocytes by human M2-like macrophages. At concentrations down to 0.1 nM, RvE4 increased macrophage erythrophagocytosis, an important pro-resolving function that was diminished due to metabolic transformation. The results provided herein contribute to a novel molecular insight on the further local metabolization of RvE4, the newest member among the SPM superfamily.

Lipid mediators in neutrophil biology: inflammation, resolution and beyond

“…RvE4 biosynthesis was confirmed by independent investigators [11]. Human neutrophils convert the bioactive RvE4 to the inactive product v-20 hydroxylated metabolite (20-OH-RvE4) [12]. RvE4 has been identified in human cerebrospinal fluid [13], and in plasma from COVID-19 patients [14].…”

Is Lipid Metabolism of Value in Cancer Research and Treatment? Part II: Role of Specialized Pro-Resolving Mediators in Inflammation, Infections, and Cancer

“…Using targeted LC-MS/MS analysis and UV spectrophotometry, RvE4 was proven to be metabolized to the inactive state for 20-OH-RvE4. These metabolites have reduced bioactions in stimulating the macrophage efferocytosis of human senescent erythrocytes when compared to RvE4 [ 105 ]. In addition, RvE4 also stimulates the macrophage efferocytosis of apoptotic neutrophils and accelerates the resolution of hemorrhagic exudates in vivo in mice [ 58 ].…”