Gut bacterial-derived 12,13-diHOME promotes M1-like inflammatory macrophage polarization and trained immunity targeting interferon responses [h-Mf-RNA-seq]. Gut bacterial-derived 12,13-diHOME promotes M1-like inflammatory macrophage polarization and trained immunity targeting interferon responses [h-Mf-RNA-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 bulk RNA-sequencing (RNA-seq) on monocyte-derived human macrophages from two donors exposed to either vehicle (DMSO), 12,13-diHOME or a combination of 12,13-diHOME and peanut flour (Pnut). We focused our RNA-Seq analyses on 4, 8, and 24 hours post exposure.

婴幼儿粪便中细菌源性脂质12,13-diHOME浓度升高，会增加儿童期特应性（atopy）与哮喘发生的风险，但该脂质如何介导疾病易感性的具体机制尚不明确。本研究证实，经12,13-diHOME处理的巨噬细胞会呈现促炎性IL-1β高表达、CD206低表达的M1样极化表型，并降低细菌吞噬能力。在共培养实验中，抗原联合12,13-diHOME可进一步提升M1样细胞比例，促进CD20+CD38-IgD-CD27+记忆性B细胞扩增与免疫球蛋白E（IgE）产生。表观遗传分析显示，12,13-diHOME处理可促进DNA甲基化与染色质压缩，特异性降低干扰素刺激应答元件（interferon-stimulated response elements, ISRE）与转录因子结合位点的可及性。体内实验中，在小鼠气道过敏性致敏模型里，肠道细菌源性12,13-diHOME可加重气道过敏性炎症，同时调控IL-1、IL-7、一碳代谢与Toll样受体（Toll-like receptor, TLR）信号通路。我们的研究结果表明，12,13-diHOME可重编程巨噬细胞效应功能、B细胞相互作用与表观遗传修饰，其介导的表型变化可能参与塑造早期生命微生物组（microbiome）发育，并介导儿童期与过敏性致敏相关的先天免疫功能异常。
实验整体设计：为阐明12,13-diHOME介导M1样巨噬细胞极化的具体机制，我们对两名供体来源的单核细胞源性人巨噬细胞进行批量RNA测序（bulk RNA-sequencing, RNA-seq），将细胞分别以溶剂对照（二甲基亚砜, DMSO）、12,13-diHOME或12,13-diHOME联合花生粉（peanut flour, Pnut）处理，并分别在处理后4、8、24小时进行RNA测序分析。