Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605.
Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605
J Immunol. 2018 Apr 1;200(7):2291-2303. doi: 10.4049/jimmunol.1600924. Epub 2018 Feb 14.
Binge/moderate alcohol suppresses TLR4-MyD88 proinflammatory cytokines; however, alcohol's effects on TLR-TRIF signaling, especially after in vivo exposure in humans, are unclear. We performed a comparative analysis of the TLR4-MyD88, TLR4-TRIF, and TLR3-TRIF pathways in human monocytes following binge alcohol exposure. Mechanistic regulation of TLR-TRIF signaling by binge alcohol was evaluated by analyzing IRF3 and TBK1, upstream regulator protein phosphatase 1 (PP1), and immunoregulatory stress proteins HspA1A and XBP-1 in alcohol-treated human and mouse monocytes/macrophages. Two approaches for alcohol exposure were used: in vivo exposure of primary monocytes in binge alcohol-consuming human volunteers or in vitro exposure of human monocytes/murine macrophages to physiological alcohol concentrations (25-50 mM ethanol), followed by LPS (TLR4) or polyinosinic-polycytidylic acid (TLR3) stimulation ex vivo. In vivo and in vitro binge alcohol exposure significantly inhibited the TLR4-MyD88 cytokines TNF-α and IL-6, as well as the TLR4-TRIF cytokines/chemokines IFN-β, IP-10, and RANTES, in human monocytes, but not TLR3-TRIF-induced cytokines/chemokines, as detected by quantitative PCR and ELISA. Mechanistic analyses revealed TBK-1-independent inhibition of the TLR4-TRIF effector IRF3 in alcohol-treated macrophages. Although stress protein XBP-1, which is known to regulate IRF3-mediated IFN-β induction, was not affected by alcohol, HspA1A was induced by in vivo alcohol in human monocytes. Alcohol-induced HspA1A was required for inhibition of TLR4-MyD88 signaling but not TLR4-TRIF cytokines in macrophages. In contrast, inhibition of PP1 prevented alcohol-mediated TLR4-TRIF tolerance in macrophages. Collectively, our results demonstrate that in vivo and in vitro binge alcohol exposure in humans suppresses TLR4-MyD88 and TLR4-TRIF, but not TLR3-TRIF, responses. Whereas alcohol-mediated effects on the PP1-IRF3 axis inhibit the TLR4-TRIF pathway, HspA1A selectively suppresses the TLR4-MyD88 pathway in monocytes/macrophages.
binge/中度饮酒可抑制 TLR4-MyD88 促炎细胞因子；然而，酒精对 TLR-TRIF 信号通路的影响，特别是在人体暴露于酒精后的影响尚不清楚。我们在人类单核细胞中进行了 binge 饮酒后 TLR4-MyD88、TLR4-TRIF 和 TLR3-TRIF 通路的比较分析。通过分析 IRF3 和 TBK1、上游调节蛋白蛋白磷酸酶 1（PP1）以及免疫调节应激蛋白 HspA1A 和 XBP-1，评估了 binge 饮酒对 TLR-TRIF 信号通路的机制调节作用，这些蛋白存在于酒精处理的人类和小鼠单核细胞/巨噬细胞中。我们使用了两种酒精暴露方法：在 binge 饮酒的人类志愿者的原代单核细胞中进行体内暴露，或在生理酒精浓度（25-50mM 乙醇）下对人类单核细胞/小鼠巨噬细胞进行体外暴露，然后进行 LPS（TLR4）或聚肌苷酸-聚胞苷酸（TLR3）刺激。体内和体外 binge 饮酒显著抑制了人类单核细胞中 TLR4-MyD88 细胞因子 TNF-α和 IL-6，以及 TLR4-TRIF 细胞因子/趋化因子 IFN-β、IP-10 和 RANTES，但对 TLR3-TRIF 诱导的细胞因子/趋化因子没有影响，这通过定量 PCR 和 ELISA 检测到。机制分析显示，TBK-1 独立抑制了酒精处理的巨噬细胞中 TLR4-TRIF 效应物 IRF3。尽管应激蛋白 XBP-1 已知可调节 IRF3 介导的 IFN-β诱导，但酒精并未影响 XBP-1，相反，HspA1A 可被体内酒精诱导。在人类单核细胞中，酒精诱导的 HspA1A 是抑制 TLR4-MyD88 信号通路所必需的，但不是抑制巨噬细胞中 TLR4-TRIF 细胞因子所必需的。相反，抑制 PP1 可防止酒精介导的巨噬细胞中 TLR4-TRIF 耐受。总的来说，我们的结果表明，在人类中进行体内和体外 binge 饮酒可抑制 TLR4-MyD88 和 TLR4-TRIF，但不抑制 TLR3-TRIF 反应。虽然酒精对 PP1-IRF3 轴的影响可抑制 TLR4-TRIF 通路，但 HspA1A 选择性抑制单核细胞/巨噬细胞中的 TLR4-MyD88 通路。
