Linoleic acid‐derived diol 12,13‐ DiHOME enhances NLRP3 inflammasome activation in macrophages

Abstract 12,13‐dihydroxy‐9z‐octadecenoic acid (12,13‐DiHOME) is a linoleic acid diol derived from cytochrome P‐450 (CYP) epoxygenase and epoxide hydrolase (EH) metabolism. 12,13‐DiHOME is associated with inflammation and mitochondrial damage in the innate immune response, but how 12,13‐DiHOME contributes to these effects is unclear. We hypothesized that 12,13‐DiHOME enhances macrophage inflammation through effects on NOD‐like receptor protein 3 (NLRP3) inflammasome activation. To test this hypothesis, we utilized human monocytic THP1 cells differentiated into macrophage‐like cells with phorbol myristate acetate (PMA). 12,13‐DiHOME present during lipopolysaccharide (LPS)‐priming of THP1 macrophages exacerbated nigericin‐induced NLRP3 inflammasome activation. Using high‐resolution respirometry, we observed that priming with LPS+12,13‐DiHOME altered mitochondrial respiratory function. Mitophagy, measured using mito‐Keima, was also modulated by 12,13‐DiHOME present during priming. These mitochondrial effects were associated with increased sensitivity to nigericin‐induced mitochondrial depolarization and reactive oxygen species production in LPS+12,13‐DiHOME‐primed macrophages. Nigericin‐induced mitochondrial damage and NLRP3 inflammasome activation in LPS+12,13‐DiHOME‐primed macrophages were ablated by the mitochondrial calcium uniporter (MCU) inhibitor, Ru265. 12,13‐DiHOME present during LPS‐priming also enhanced nigericin‐induced NLRP3 inflammasome activation in primary murine bone marrow‐derived macrophages. In summary, these data demonstrate a pro‐inflammatory role for 12,13‐DiHOME by enhancing NLRP3 inflammasome activation in macrophages.