Neale Peta A, Achard Maud E S, Escher Beate I, Leusch Frederic D L
Australian Rivers Institute, Griffith School of Environment, Griffith University, Southport, QLD 4222, Australia.
Environ Sci Process Impacts. 2017 Sep 20;19(9):1126-1133. doi: 10.1039/c6em00541a.
Environmental waters can contain a wide range of micropollutants. Bioanalytical test batteries using assays indicative of different stages of cellular toxicity pathways, such as adaptive stress responses, have been applied to a range of water samples. Oxidative stress response assays have proven to be sensitive tools, but the mechanism by which water samples are inducing the oxidative stress response remains unclear because both electrophiles and reactive oxygen species (ROS) may activate the Nrf2-antioxidant response element (ARE) pathway. The current study aimed to explore the underlying mechanisms of the oxidative stress response triggered by exposure to surface water extracts previously shown to be active in the ARE GeneBLAzer oxidative stress response assay. ROS formation and changes in glutathione (GSH) concentration were assessed in human liver cells exposed to water extracts from a large river in addition to individual chemicals that were detected in these water extracts and reported to be active in the ARE GeneBLAzer assay in a previous study. Many of the surface water samples induced ROS formation and decreased the GSH to glutathione disulfide (GSSG) ratio, suggesting that the formation of ROS is an important mechanism. However, some of the most responsive samples in the ARE GeneBLAzer assay, as well as the individual chemicals, did not have a significant effect on either ROS formation or the GSH/GSSG ratio, suggesting a different mechanism. Antioxidants can also induce the Nrf2-ARE pathway and the ARE GeneBLAzer assay may also detect compounds that activate ARE by Nrf2-independent mechanisms, thus further research is required to characterise active chemicals in oxidative stress response assays. However, these tests are still useful for quantifying the integrated cellular response to multiple molecular initiating events and can be used complementary to assays indicative of specific effects, such as receptor-mediated assays.
环境水体中可能含有多种微污染物。已将使用指示细胞毒性途径不同阶段的分析方法（如适应性应激反应）的生物分析测试组合应用于一系列水样。氧化应激反应分析已被证明是灵敏的工具，但水样诱导氧化应激反应的机制仍不清楚，因为亲电试剂和活性氧（ROS）都可能激活Nrf2-抗氧化反应元件（ARE）途径。本研究旨在探讨暴露于先前在ARE基因发光氧化应激反应分析中显示有活性的地表水提取物所引发的氧化应激反应的潜在机制。除了在这些水提取物中检测到并在先前研究中报道在ARE基因发光分析中有活性的个别化学物质外，还评估了暴露于一条大河的水提取物的人肝细胞中的ROS形成和谷胱甘肽（GSH）浓度变化。许多地表水样品诱导了ROS形成并降低了GSH与氧化型谷胱甘肽（GSSG）的比率，这表明ROS的形成是一个重要机制。然而，在ARE基因发光分析中一些反应最强烈的样品以及个别化学物质，对ROS形成或GSH/GSSG比率均无显著影响，这表明存在不同的机制。抗氧化剂也可诱导Nrf2-ARE途径，且ARE基因发光分析也可能检测到通过Nrf2非依赖性机制激活ARE的化合物，因此需要进一步研究以表征氧化应激反应分析中的活性化学物质。然而，这些测试对于量化细胞对多种分子起始事件的综合反应仍然有用，并且可与指示特定效应的分析方法（如受体介导的分析方法）互补使用。
