Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland; ETH Zürich, Department of Environmental Systems Science, 8092 Zürich, Switzerland.
Environ Pollut. 2017 Feb;221:105-115. doi: 10.1016/j.envpol.2016.11.046. Epub 2016 Dec 20.
Opioid drugs, such as morphine (MO), detected in aquatic environments worldwide, may harm fish due to their semi-persistence and ability to potently interact with molecular targets conserved across vertebrates. Here, we established a waterborne bacterial lipopolysaccharide (LPS) challenge assay with zebrafish embryos as a model to investigate chemically-induced disruption of the innate immune system, and used it to study the effects of MO exposure. Exposure to 1 mg/L MO resulted in pronounced immunosuppression, reflected in downregulation of several inflammation-related genes, including myd88, trif, traf6, p38, nfκb2, il-1β, il-8 and ccl34a. Fish exposed to 1 mg/L MO accumulated 11.7 ng/g (wet weight) of MO, a concentration comparable to that reported in blood of chronic drug abusers subject to higher infection rates. Surprisingly, exposure to lower MO concentrations (100 ng/L-100 μg/L) led to exacerbation of LPS-induced inflammation. Two ATP-binding cassette (ABC) transporters known to be involved in the xenobiotic efflux - abcb4 and abcc2, also known as multixenobiotic resistance (MXR) transporters - were downregulated at 100 ng/L MO. We hypothesized that ABC/MXR transporters could modulate the severity of inflammation by being involved in efflux of LPS, thus regulating its accumulation in the organism. Indeed, we could demonstrate that blocking of ABC/MXR transporters by an inhibitor, cyclosporine A, results in stronger inflammation, coinciding with higher LPS accumulation, as visualized with fluorescently labeled LPS. Our work demonstrates that MO can disrupt fish innate immune responses at environmentally relevant concentrations. We also provide evidence for a role of ABC/MXR transporters in LPS efflux in fish. These finding may be applicable across other taxa, as ABC transporters are evolutionary conserved. Since diverse environmentally present chemicals are known to interfere with ABC/MXR transporters' expression or activity, our discovery raises concerns about potential adverse effects of such compounds on the immune system responses in aquatic organisms.
阿片类药物，如吗啡（MO），在全球水生环境中被检测到，由于其半持久性和与脊椎动物中保守的分子靶标强烈相互作用的能力，可能会对鱼类造成伤害。在这里，我们建立了一个基于水传播的细菌脂多糖（LPS）挑战的斑马鱼胚胎模型，以研究化学物质引起的先天免疫系统的破坏，并使用它来研究 MO 暴露的影响。暴露于 1mg/L MO 导致明显的免疫抑制，这反映在几个炎症相关基因的下调，包括 myd88、trif、tra f6、p38、nfκb2、il-1β、il-8 和 ccl34a。暴露于 1mg/L MO 的鱼类体内积累了 11.7ng/g（湿重）的 MO，这一浓度与报告的慢性药物滥用者血液中的浓度相当，这些人更容易受到感染。令人惊讶的是，暴露于较低浓度的 MO（100ng/L-100μg/L）会加剧 LPS 诱导的炎症。两种已知参与外源性化合物外排的三磷酸腺苷（ATP）结合盒（ABC）转运蛋白 - abcb4 和 abcc2，也称为多外源性化合物耐药（MXR）转运蛋白 - 在 100ng/L MO 时被下调。我们假设 ABC/MXR 转运蛋白可以通过参与 LPS 的外排来调节炎症的严重程度，从而调节其在生物体中的积累。事实上，我们可以证明，通过抑制剂环孢菌素 A 阻断 ABC/MXR 转运蛋白会导致更强的炎症，同时 LPS 的积累也更高，这可以通过荧光标记的 LPS 可视化。我们的工作表明，MO 可以在环境相关浓度下破坏鱼类的先天免疫反应。我们还提供了 ABC/MXR 转运蛋白在鱼类 LPS 外排中的作用的证据。这些发现可能适用于其他分类群，因为 ABC 转运蛋白在进化上是保守的。由于已知多种环境存在的化学物质会干扰 ABC/MXR 转运蛋白的表达或活性，因此我们的发现引起了人们对这些化合物对水生生物免疫系统反应可能产生的不利影响的关注。
