Here we report that macrophage AHR/TLR/STAT signaling axis is implicated in the colon colitis induced by non-canonical AHR ligand aflatoxin B1 (AFB1). In BALB/c mice gavaged with 5, 25 and 50 µg/kg body weight/day AFB1, we observed severe colitis featured by over-recruitment of myeloid lineage immune cells such as monocytes/macrophage in colon lamina propria. Stressed and damaged colon epithelial cells were observed in low-dose group, while twisted and shortened intestinal crypts being found in middle dose group. Severe tissue damage was induced in the high-dose group. Dose-dependent increases of ROS, NO, and decrease of mitochondrial ROS-suppressor STAT3 were observed in the exposure groups. Further investigation in AFB1-treated human macrophage model found: (1) functional adaptations such as elevation of TNF-alpha and IL-6 secretion, stimulation of phagocytosis, elevation of LTE4 level; (2) overall inflammatory status confirmed by RNA-sequence analysis, in line with up-regulation of immune functional proteins such as ICAM-1, IDO-1, NF-kB-p65, NLRP3, COX-2 and iNOS; (3) mRNA disruption of mitochondrial oxidative phosphorylation complex I units and STATs; (4) perturbation of AHR/TLR/STAT3 signaling axis, including elevated AHR, TLR2, TLR4, and decreased STAT3, p-STAT3 Ser727. Mechanism investigation revealed regulatory links of ligand-dependent AHR/TLR4/STAT3. AHR-TLR4 together regulate MyD88, and STAT3 may be directly regulated by MyD88 (TLR4 downstream molecule) upon AHR/TLR4 binding with ligands. Solely protein level changes of AHR/TLR4 cannot regulate STAT3. Our study suggests that macrophage AHR/TLR4/STAT3 is involved with the colitis induced by sub-acute exposure to AFB1. Future follow-up study will focus on the intervention of the colitis using AHR-anti-inflammatory ligands.

在这里，我们报告巨噬细胞 AHR/TLR/STAT 信号轴与非经典 AHR 配体黄曲霉毒素 B1 (AFB1) 诱导的结肠结肠炎有关。在灌胃 5、25 和 50 微克/千克体重/天 AFB1 的 BALB/c 小鼠中，我们观察到严重的结肠炎，其特征是结肠固有层中的骨髓系免疫细胞（例如单核细胞/巨噬细胞）过度募集. 低剂量组结肠上皮细胞受压损伤，中剂量组肠隐窝扭曲缩短。高剂量组引起严重的组织损伤。在暴露组中观察到 ROS、NO 的剂量依赖性增加和线粒体 ROS 抑制因子 STAT3 的减少。对 AFB1 处理的人巨噬细胞模型的进一步研究发现：（1）功能适应性，如 TNF-α 和 IL-6 分泌的升高，吞噬作用的刺激，LTE4 水平的升高；(2) 通过 RNA 序列分析证实的整体炎症状态，与免疫功能蛋白如 ICAM-1、IDO-1、NF-kB-p65、NLRP3、COX-2 和 iNOS 的上调一致；(3) 线粒体氧化磷酸化复合物 I 单位和 STATs 的 mRNA 破坏；(4)AHR/TLR/STAT3信号轴扰动，包括AHR、TLR2、TLR4升高，STAT3、p-STAT3 Ser727降低。机制研究揭示了配体依赖性 AHR/TLR4/STAT3 的调控联系。AHR-TLR4 共同调节 MyD88，而 STAT3 可能在 AHR/TLR4 与配体结合后直接受 MyD88（TLR4 下游分子）调节。仅仅改变 AHR/TLR4 的蛋白水平并不能调节 STAT3。我们的研究表明巨噬细胞 AHR/TLR4/STAT3 与亚急性暴露于 AFB1 诱导的结肠炎有关。未来的后续研究将集中在使用 AHR 抗炎配体干预结肠炎。在 AHR/TLR4 与配体结合后，STAT3 可能直接受 MyD88（TLR4 下游分子）的调控。仅仅改变 AHR/TLR4 的蛋白水平并不能调节 STAT3。我们的研究表明巨噬细胞 AHR/TLR4/STAT3 与亚急性暴露于 AFB1 诱导的结肠炎有关。未来的后续研究将集中在使用 AHR 抗炎配体干预结肠炎。在 AHR/TLR4 与配体结合后，STAT3 可能直接受 MyD88（TLR4 下游分子）的调控。仅仅改变 AHR/TLR4 的蛋白水平并不能调节 STAT3。我们的研究表明巨噬细胞 AHR/TLR4/STAT3 与亚急性暴露于 AFB1 诱导的结肠炎有关。未来的后续研究将集中在使用 AHR 抗炎配体干预结肠炎。