Drug-Vitamin Interactions Mediated by the Thiamine Transporter, SLC19A3

维生素B1（硫胺素）对正常细胞代谢至关重要。硫胺素缺乏症，特别是湿性和干性脚气病，以及与硫胺素缺乏症有关的严重神经系统综合征韦尼克脑病，与营养不足和硫胺素吸收不良（如酗酒、减肥手术）或高代谢状态（如癌症）引起的许多疾病和病症有关。然而，最近一项灾难性的临床药物试验（该试验因使用federatinib导致韦尼克脑病而终止）后进行的机制研究强调了药物制剂对硫胺素缺乏症的重要性。也就是说，federatinib被证明是通过硫胺素转运体SLC19A3吸收硫胺素的有效抑制剂。在这项研究应用中，我们将NIH和USDA营养支持的研究人员聚集在一起，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，我们提出这些药物-硫胺素相互作用产生可检测的代谢特征，与依赖硫胺素焦磷酸（TPP）的酶活性降低有关，TPP是硫胺素的活性代谢物。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。提出了三个目标：1。开发并鉴定SLC19A3人源化转基因小鼠模型，该模型可作为动物模型来测试药物引起硫胺素缺乏症的潜力。2. 通过随机交叉研究确定二甲双胍对健康志愿者体内硫胺素的药代动力学和代谢特征的影响；和3。利用一种新型的小型化方法筛选2000个处方药物和生物活性化合物库，鉴定抑制SLC19A3的化合物，并利用定量构效关系模型（QSAR）确定抑制SLC19A3的关键结构部分。拟议的研究将采用多层方法，包括在健康志愿者中进行药物-维生素相互作用研究；代谢组学方法鉴定硫胺素的代谢特征；小分子筛选筛选SLC19A3抑制剂；SLC19A3人源化小鼠模型的建立和表征。总的来说，这些新颖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。具体来说，这些研究将带来新的工具，可用于营养研究，并认识到治疗药物可能会对硫胺素的吸收产生不利影响，并导致硫胺素缺乏。

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.