Burnette Elizabeth M, Grodin Erica N, Olmstead Richard, Ray Lara A, Irwin Michael R
Department of Psychology, University of California at Los Angeles, Los Angeles, California, USA.
Neuroscience Interdepartmental Program, University of California at Los Angeles, Los Angeles, California, USA.
Alcohol Clin Exp Res (Hoboken). 2023 Oct;47(10):1859-1868. doi: 10.1111/acer.15173. Epub 2023 Aug 26.
Inflammation has been associated with alcohol use disorder (AUD). A novel method to characterize AUD-related immune signaling involves probing Toll-like receptor (TLR)-4 stimulated monocyte production of intracellular cytokines (ICCs) via lipopolysaccharide (LPS). We evaluated relationships between AUD and ICC production at rest and after LPS stimulation.
We analyzed blood samples from 36 participants (AUD N = 14; Controls N = 22), collected across time, with ICC expression assessed at rest (i.e., unstimulated) and following stimulation with LPS (i.e., a total of 5 repeated unstimulated or stimulated measures/participant). Markers assessed included tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), TNF-α and IL-6 co-expression, and interferon (IFN). For each marker, we constructed linear mixed models with AUD, LPS, and timepoint as fixed effects (BMI as covariate), allowing for random slope and intercept. AUD × LPS was included as an interaction.
For TLR4-stimulated monocyte production of TNF-α, there were effects of AUD (p < 0.01), LPS (p < 0.001), and AUD × LPS interaction (p < 0.05), indicating that individuals with AUD showed greater unstimulated- and stimulated monocyte expression of TNF-α. Similarly, for TLR4-stimulated monocyte co-expression of TNF-α and IL-6, there were effects of AUD (p < 0.01), LPS (p < 0.001), and AUD × LPS interaction (p < 0.05). No AUD or LPS effects were found for IL-6. Timepoint effects were observed on IL-6 and TNF-α/IL-6 co-expression (p < 0.001). Finally, for IFN there were also effects of AUD (p < 0.05), LPS (p < 0.001), and AUD × LPS (p < 0.001).
Individuals with AUD showed greater resting or unstimulated levels of intracellular monocyte expression of TNF-α and IL-6/TNF-α co-expression than controls. AUD was associated with increases in TLR4-stimulated monocyte production of TNF-α and co-production of IL-6 and TNF-α. This is, to our knowledge, the first study to investigate relationships between AUD and monocyte production of proinflammatory cytokines, at rest and in response to TLR4 stimulation with LPS. The study extends previous findings on the roles of proinflammatory cytokines in AUD and serves as a critical proof of concept for the use of this method to probe neuroimmune mechanisms underlying AUD.
炎症与酒精使用障碍（AUD）有关。一种表征与AUD相关的免疫信号传导的新方法涉及通过脂多糖（LPS）探测Toll样受体（TLR）-4刺激的单核细胞产生细胞内细胞因子（ICC）。我们评估了AUD与静息及LPS刺激后ICC产生之间的关系。
我们分析了36名参与者（AUD组n = 14；对照组n = 22）不同时间采集的血样，评估静息（即未刺激）及LPS刺激后（即每位参与者共5次重复的未刺激或刺激测量）的ICC表达。评估的标志物包括肿瘤坏死因子-α（TNF-α）、白细胞介素-6（IL-6）、TNF-α和IL-6共表达以及干扰素（IFN）。对于每个标志物，我们构建了以AUD、LPS和时间点为固定效应（BMI作为协变量）的线性混合模型，允许随机斜率和截距。AUD×LPS作为交互项纳入。
对于TLR4刺激的单核细胞产生TNF-α，存在AUD效应（p < 0.01）、LPS效应（p < 0.001）以及AUD×LPS交互效应（p < 0.05），表明AUD个体未刺激和刺激后的单核细胞TNF-α表达更高。同样，对于TLR4刺激的单核细胞TNF-α和IL-6共表达，存在AUD效应（p < 0.01）、LPS效应（p < 0.001）以及AUD×LPS交互效应（p < 0.05）。未发现IL-6有AUD或LPS效应。观察到时间点对IL-6和TNF-α/IL-6共表达有影响（p < 0.001）。最后对于IFN，也存在AUD效应（p < 0.05）、LPS效应（p < 0.001）以及AUD×LPS效应（p < 0.001）。
与对照组相比，AUD个体静息或未刺激状态下细胞内单核细胞TNF-α表达水平以及IL-6/TNF-α共表达水平更高。AUD与TLR4刺激的单核细胞TNF-α产生增加以及IL-6和TNF-α共同产生增加有关。据我们所知，这是第一项研究AUD与静息及LPS刺激TLR4后单核细胞促炎细胞因子产生之间关系的研究。该研究扩展了先前关于促炎细胞因子在AUD中作用的发现，并为使用该方法探究AUD潜在的神经免疫机制提供了关键的概念验证。
