Probing the biochemistry of toxic metals in the bloodstream

探索血液中有毒金属的生物化学

• 批准号: RGPIN-2014-04156
• 负责人: Gailer, Juergen
• 金额: $ 1.89万
• 依托单位: University of Calgary
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610865
• 关键词: Probing; biochemistry; toxic; metals; bloodstream

Human activities, such as fossil fuel consumption and mining, emit quantities of toxic metals (arsenic, cadmium, mercury and manganese) that rival or exceed natural global emissions. These emissions are expected in increase. Coal consumption, for example, is expected to increase by 20% over the next 25 years. In addition, millions of people are exposed to toxic metals at their workplace through the inhalation/ingestion of toxic metal-containing dusts (e.g. sheet metal flame cutting, welding, etc.). Since toxic metals are absorbed from the gastrointestinal tract and/or the lungs, they will eventually enter the bloodstream. Although we accurately know the concentrations of the aforementioned toxic metals in the human bloodstream of the average population (these data are determined in regular intervals by the Centers of Disease Control and Prevention of the United States), we don't know at present what these concentrations mean. This undesirable situation must be largely attributed to our lack of understanding the fundamental chemical processes that unfold once these toxic metals enter the bloodstream, which in turn is associated with the difficulty of analyzing blood. Blood plasma, for example, contains up to 10,000 individual proteins. To gain much needed insight into the interactions of toxic metals in the bloodstream, my group has developed a unique visualization method for the analysis of plasma. Instead of analyzing the latter for the thousands of proteins, our method specifically analyzes plasma for those proteins which contain a bound metal and are therefore referred to as metalloproteins. The latter deliver sufficient amounts of dietary iron, copper and zinc to our organs where they are important building blocks for the assembly of proteins which maintain vital biochemical processes. From a toxicological point of view, the binding of dietary iron, copper and zinc to plasma proteins in the bloodstream is a critical step in their metabolism which can be adversely affected by toxic metals. In addition, a toxic metal may be inadvertently transported to an organ (where it causes toxicity) by binding to certain metalloproteins. Furthermore, the influx of a toxic metal into the bloodstream may change the concentration of certain metalloproteins over time. In order to probe all of these toxicologically highly relevant processes, we will use rabbits as a model organism. We will first conduct experiments with rabbit plasma to which a toxic metal is added. Simultaneous analysis of the plasma for metalloproteins and the added toxic metal will provide insight into the transport of the latter in the bloodstream and will contribute to establish the mechanisms which define the target organ of any given toxic metal. Next we will carry out similar experiments with rabbit whole blood. These investigations are expected to allow us to isolate novel toxic metal containing metabolites, which will be structurally characterized at the Canadian Light Source. This is important to identify metabolites which play a critical role in their toxicity. Since the methodology that we will employ can analyze plasma in 25 minutes, we will complement the aforementioned "test tube" experiments with studies using anesthesized rabbits. After the injection with a toxic metal, the analysis of plasma for the contained metalloproteins over an 8 h period will reveal changes of certain metalloprotein concentrations over time. It is expected that these studies will provide unique insight into the systemic toxicity of toxic metals. Overall, my research program will allow us to obtain fundamentally new insight into the toxicology of metals in the mammalian bloodstream, which will ultimately contribute to better inform Canadian public policy on the regulation of toxic metals.

化石燃料消耗和采矿等人类活动排放的有毒金属（砷、镉、汞和锰）数量相当于或超过全球自然排放量。这些排放量预计还会增加。例如，预计未来 25 年煤炭消耗量将增加 20%。此外，数百万人在工作场所通过吸入/摄入有毒金属粉尘（例如金属板材火焰切割、焊接等）而接触到有毒金属。由于有毒金属是从胃肠道和/或肺部吸收的，因此它们最终会进入血液。尽管我们准确地知道普通人群血液中上述有毒金属的浓度（这些数据由美国疾病控制和预防中心定期测定），但我们目前不知道这些有毒金属的具体含量。浓度意思。这种不良情况很大程度上归因于我们缺乏对这些有毒金属进入血液后所发生的基本化学过程的了解，这反过来又与分析血液的困难有关。例如，血浆中含有多达 10,000 种蛋白质。为了深入了解血液中有毒金属的相互作用，我的团队开发了一种独特的血浆分析可视化方法。我们的方法不是分析后者的数千种蛋白质，而是专门分析血浆中那些含有结合金属的蛋白质，因此被称为金属蛋白。后者向我们的器官输送足够量的膳食铁、铜和锌，它们是维持重要生化过程的蛋白质组装的重要组成部分。从毒理学的角度来看，膳食铁、铜和锌与血液中血浆蛋白的结合是其代谢的关键步骤，可能会受到有毒金属的不利影响。此外，有毒金属可能会通过与某些金属蛋白结合而无意中转运至器官（引起毒性）。此外，有毒金属流入血液可能会随着时间的推移改变某些金属蛋白的浓度。为了探索所有这些毒理学高度相关的过程，我们将使用兔子作为模型生物。我们将首先用添加了有毒金属的兔子血浆进行实验。对血浆中金属蛋白和添加的有毒金属的同时分析将深入了解后者在血流中的转运，并将有助于建立定义任何给定有毒金属的靶器官的机制。接下来我们将用兔全血进行类似的实验。这些研究预计将使我们能够分离出含有代谢物的新型有毒金属，这些代谢物将在加拿大光源处进行结构表征。这对于识别对其毒性起关键作用的代谢物非常重要。由于我们将采用的方法可以在 25 分钟内分析血浆，因此我们将通过使用麻醉兔子的研究来补充上述“试管”实验。注射有毒金属后，8 小时内对血浆中所含金属蛋白的分析将揭示某些金属蛋白浓度随时间的变化。预计这些研究将为有毒金属的全身毒性提供独特的见解。总体而言，我的研究计划将使我们能够对哺乳动物血液中金属的毒理学获得全新的见解，这最终将有助于更好地为加拿大有关有毒金属监管的公共政策提供信息。