Identification and Actions of the Maresin 1 Metabolome in Infectious Inflammation

Maresin 1 (MaR1) is an immunoresolvent that governs resolution of acute inflammation, and its local metabolism in the context of infectious inflammation is of interest. In this study, we investigated the MaR1 metabolome in infectious exudates and its bioactions in regulating leukocyte responses in the context of bacterial infection. In Escherichia coli infectious exudates, MaR1 was temporally regulated with maximal levels at 4 h (2.2 ± 0.4 pg/lavage). In these exudates we also identified two novel products, and their structure elucidation gave 22-hydroxy-MaR1 and 14-oxo-MaR1. Using human primary leukocytes, we found that neutrophils primarily produced 22-OH-MaR1, whereas the main macrophage product was 14-oxo-MaR1. Both 22-OH-MaR1 and 14-oxo-MaR1 incubated with human primary macrophages gave dose-dependent increases in macrophage phagocytosis of ∼75% at 1 pM 22-OH-MaR1 and ∼25% at 1 pM 14-oxo-MaR1, whereas 14-oxo-MaR1 was less active than MaR1 at higher concentrations. Together these findings establish the temporal regulation of MaR1 during infectious inflammation, and elucidate the structures and actions of two novel MaR1 further metabolites that carry bioactivities.