Drug-Vitamin Interactions Mediated by the Thiamine Transporter, SLC19A3

摘要维生素B1(硫胺素)在细胞正常代谢中起着至关重要的作用。硫胺素缺乏症，特别是湿性和干性脚气病，以及韦尼克脑病，是一种与硫胺素缺乏有关的严重神经综合征，与许多疾病和条件有关，这些疾病和状况是由于硫胺素营养不足和吸收不良(例如酒精中毒、减肥手术)或高代谢状态(例如癌症)引起的。然而，最近一次灾难性的临床药物试验(因为药物非卓替尼导致韦尼克脑病而终止)之后的机制研究强调了药物制剂作为硫胺素缺乏症的贡献者的重要性。也就是说，非德拉替尼被证明是通过硫胺转运体SLC19A3有效地抑制硫胺吸收的药物。在这项研究应用中，我们汇集了美国国立卫生研究院和美国农业部营养支持的研究人员，以响应PAR-15-024。特别是，我们建议测试常用药物抑制SLC19A3介导的硫胺素肠道吸收导致药物-维生素相互作用的假设。其次，我们认为这些药物与硫胺的相互作用产生了可检测到的代谢特征，这与依赖于硫胺的活性代谢物焦磷硫胺(TPP)的酶的活性降低有关。我们的假设是基于我们实验室令人兴奋的初步研究表明，几种处方药，如二甲双胍、乙胺嘧啶和阿米洛利，是SLC19A3的抑制剂。1.建立SLC19A3人源化转基因小鼠模型，作为检测药物是否可能导致硫胺素缺乏的动物模型。2.通过随机交叉研究确定二甲双胍对硫胺素在健康志愿者体内的药代动力学和代谢特征的影响；3.使用一种新的小型化方法来筛选包含2000种处方药和生物活性的化合物库，以识别抑制SLC19A3的化合物，并使用定量结构活性关系建模(QSAR)确定抑制SLC19A3的关键结构部分。拟议的研究将使用多层次方法，包括健康志愿者的药物-维生素相互作用研究；识别硫胺素代谢特征的代谢组学方法；识别SLC19A3抑制剂的小分子筛选；以及SLC19A3人源化小鼠模型的创建和表征。总而言之，这些新的研究将导致对药物-维生素相互作用及其代谢特征的新认识。具体地说，这些研究将带来可用于营养研究的新工具，并认识到治疗药物可能对硫胺素的吸收产生不利影响，并导致硫胺素缺乏症。

Abstract Vitamin B1 (thiamine) is critical in normal cellular metabolism. Thiamine deficiency diseases, notably wet and dry beriberi, and Wernicke's encephalopathy, a severe neurological syndrome associated with thiamine deficiency, are associated with many diseases and conditions that result from under-nutrition and malabsorption of thiamine (e.g. alcoholism, bariatric surgery) or hyper-metabolic states (e.g., cancer). However mechanistic studies following a recent and disastrous clinical drug trial (that was terminated because the drug, fedratinib, led to Wernicke's encephalopathy) highlighted the importance of pharmaceutical agents as contributors to thiamine deficiency. That is, fedratinib was shown to be a potent inhibitor of thiamine absorption via the thiamine transporter, SLC19A3. In this research application, we bring together NIH and USDA nutrition supported researchers, in response to PAR-15-024. In particular, we propose to test the hypotheses that commonly used medications inhibit SLC19A3-mediated intestinal absorption of thiamine resulting in drug-vitamin interactions. Secondly, we propose that these drug-thiamine interactions produce a detectable metabolic signature that relates to reduction in the activity of enzymes that are dependent on thiamine pyrophosphate (TPP), the active metabolite of thiamine. Our hypotheses are based on exciting preliminary studies in our laboratories demonstrating that several prescription drugs, e.g., metformin, pyrimethamine and amiloride, are inhibitors of SLC19A3. Three aims are proposed: 1. Develop and characterize a humanized transgenic mouse model of SLC19A3 that can serve as an animal model to test drugs for their potential to cause thiamine deficiency. 2. Determine the effects of metformin on the pharmacokinetics and metabolic signatures of thiamine in healthy volunteers using a randomized crossover study; and 3. Use a novel miniaturized assay to screen a 2000-compound library of prescription drugs and bioactives to identify compounds that inhibit SLC19A3 and determine the key structural moieties for SLC19A3 inhibition using quantitative structure activity relationship modeling (QSAR). A multi-tiered approach will be used for the proposed studies including drug-vitamin interaction studies in healthy volunteers; metabolomic methods to identify metabolic signatures of thiamine; small molecule screening to identify inhibitors of SLC19A3; and creation and characterization of humanized mouse models of SLC19A3. Collectively, these novel studies will lead to a new knowledge of drug-vitamin interactions and their metabolic signatures. Specifically, the studies will lead to new tools that can be used in nutrient research and to a recognition that therapeutic drugs may adversely affect thiamine absorption and contribute to thiamine deficiency.