Department of Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Str. 8-10, 10589, Berlin, Germany.
Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, 20133, Milan, Italy.
Arch Toxicol. 2018 Dec;92(12):3471-3486. doi: 10.1007/s00204-018-2321-x. Epub 2018 Oct 6.
Consumers are exposed to pesticide residues and other food contaminants via the diet. Both can exert adverse effects on different target organs via the activation of nuclear receptor pathways. Hepatotoxic effects of the widely used triazole fungicide propiconazole (Pi) are generally attributed to the activation of the constitutive androstane receptor (CAR) or the pregnane X receptor (PXR). We now investigated the effects of Pi on the aryl hydrocarbon receptor (AHR) and possible mixture toxicity when Pi is present in combination with BbF, an AHR ligand. In silico docking simulations indicate that Pi can bind to human AHR. Subsequent dual luciferase reporter gene assays in human HepG2 cells showed that Pi activates the AHR in vitro. This concentration-dependent activation was confirmed by real-time RT-PCR analyses of the model AHR target genes CYP1A1 and CYP1A2 in human HepaRG and HepG2 cells. In addition, induction of CYP1A1 protein levels and enzyme activity were recorded. Similarly, increased mRNA expression and enzyme activity of Cyp1a1 and Cyp1a2 was observed in livers of rats treated with Pi for 28 days via the diet. Gene expression analysis in AHR-knockout HepaRG cells showed no induction of CYP1A1 and CYP1A2, whereas gene expression in CAR-, and PXR-knockout cells was induced. Finally, mixture effects of Pi and BbF were analyzed in human cell lines: modeling of concentration-response curves revealed concentration additivity. In conclusion, our results demonstrate that the triazole Pi is an activator of AHR in silico, in vitro and in vivo and causes additive effects with an established AHR ligand.
消费者通过饮食接触到农药残留和其他食物污染物。这些物质都可以通过激活核受体途径对不同的靶器官产生不良影响。广泛使用的三唑类杀菌剂丙环唑（Pi）的肝毒性作用通常归因于激活组成型雄烷受体（CAR）或孕烷 X 受体（PXR）。我们现在研究了 Pi 对芳基烃受体（AHR）的影响，以及当 Pi 与 AHR 配体 BbF 同时存在时可能产生的混合物毒性。计算机对接模拟表明，Pi 可以与人 AHR 结合。随后在人 HepG2 细胞中的双荧光素酶报告基因检测显示，Pi 在体外激活了 AHR。这种浓度依赖性激活通过人 HepaRG 和 HepG2 细胞中模型 AHR 靶基因 CYP1A1 和 CYP1A2 的实时 RT-PCR 分析得到证实。此外，还记录了 CYP1A1 蛋白水平和酶活性的诱导。同样，在通过饮食用 Pi 处理 28 天的大鼠肝脏中观察到 Cyp1a1 和 Cyp1a2 的 mRNA 表达和酶活性增加。在 AHR 敲除 HepaRG 细胞中的基因表达分析显示，CYP1A1 和 CYP1A2 没有诱导，而在 CAR 和 PXR 敲除细胞中的基因表达则被诱导。最后，在人细胞系中分析了 Pi 和 BbF 的混合物效应：浓度-反应曲线的建模显示出浓度加性。总之，我们的结果表明，三唑类 Pi 在计算机、体外和体内均为 AHR 的激活剂，并与已建立的 AHR 配体产生相加作用。
