Gut bacterial-derived 12,13-diHOME promotes M1-like inflammatory macrophage polarization and trained immunity targeting interferon responses [h-Mf-ATAC-seq]

Elevated infant fecal concentrations of bacterial-derived lipid 12,13-diHOME increases risk for atopy and asthma development in childhood, mechanistically how this lipid may contribute to disease susceptibility is unknown. Here we demonstrate macrophages exposed to 12,13-diHOME exhibit inflammatory IL-1?highCD206low M1-like polarization, reduce bacterial phagocytic capacity. In co-culture assays, antigens in the presence of 12,13-diHOME further amplifies M1-like frequency, promotes CD20+CD38-IgD-CD27+ memory B cells expansion and IgE production. Epigenetic analyses indicates 12,13-diHOME exposure promotes DNA methylation, chromatin compaction, specifically diminishing access to interferon-stimulated response elements and transcription factor binding sites. In vivo, in murine airway allergic sensitization model, gut bacterial-derived 12,13-diHOME exacerbated both airway allergic inflammation and IL-1, IL-7, one-carbon metabolism and Toll-like receptor signaling. Our data suggests that 12,13-diHOME reprograms macrophage effector function, B-cell interactions and epigenetic modifications promoting phenotypes plausibly play a role in shaping early life microbiome development and innate immune dysfunction related to allergic sensitization in childhood. Overall design: To understand how 12,13-diHOME promoted M1-like macrophage polarization, we performed ATAC-seq human macrophages from four donors exposed to either vehicle (DMSO) or 12,13-diHOME or LPS.