Terasaki Tetsuya
Membrane Transport and Drug Targeing Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University.
Yakugaku Zasshi. 2021;141(4):447-462. doi: 10.1248/yakushi.20-00232.
The blood-brain barrier (BBB) consists of brain capillary endothelial cells linked by tight junctions and serves to regulate the transfer of endogenous compounds and xenobiotics between the circulating blood and brain interstitial fluid. We have developed a methodology to characterize brain-to-blood efflux transport in vivo, using the Brain Efflux Index and an in vitro culture model of the BBB, i.e., a conditionally immortalized cell line of the neurovascular unit. Employing these methods, we showed that the BBB plays an important role in protecting the brain by transporting neurotransmitters, neuromodulators, metabolites, uremic toxins, and xenobiotics together with atrial natriuretic peptide from the brain interstitial fluid to the circulating blood. We also developed a highly selective, sensitive LC-MS/MS method for simultaneous protein quantification. We found significant species differences in the expression amounts of various BBB transporter proteins among mice, rats, marmosets, cynomolgus monkeys, and humans. Among transporter proteins at the BBB, multidrug resistance protein 1 (Mdr1/Abcb1) is known to generate a concentration gradient of unbound substrate drugs between the blood and brain. Based on measurements of the intrinsic efflux transport rate of Mdr1 and the protein expression amounts of Mdr1 in mouse brain capillaries and Mdr1-expressing cell lines, we predicted the unbound drug concentration gradients of 7 drugs in the mouse brain in vivo. This was the first successful prediction of in vivo drug transport activity from in vitro experimental data and transporter protein concentration in tissues. This methodology and findings should greatly advance central nervous system barrier research.
血脑屏障（BBB）由通过紧密连接相连的脑毛细血管内皮细胞组成，其作用是调节内源性化合物和外源性物质在循环血液与脑间质液之间的转运。我们已经开发出一种方法，利用脑外排指数和血脑屏障的体外培养模型（即神经血管单元的条件永生化细胞系）来表征体内脑到血的外排转运。采用这些方法，我们表明血脑屏障通过将神经递质、神经调质、代谢物、尿毒症毒素、外源性物质以及心房利钠肽从脑间质液转运到循环血液中，在保护大脑方面发挥着重要作用。我们还开发了一种用于同时进行蛋白质定量的高选择性、灵敏的液相色谱 - 串联质谱法。我们发现小鼠、大鼠、狨猴、食蟹猴和人类之间各种血脑屏障转运蛋白的表达量存在显著的物种差异。在血脑屏障的转运蛋白中，多药耐药蛋白1（Mdr1/Abcb1）已知会在血液和大脑之间产生未结合底物药物的浓度梯度。基于对Mdr1固有外排转运速率以及小鼠脑毛细血管和表达Mdr1的细胞系中Mdr1蛋白表达量的测量，我们预测了7种药物在小鼠脑内的体内未结合药物浓度梯度。这是首次从体外实验数据和组织中的转运蛋白浓度成功预测体内药物转运活性。这种方法和研究结果应能极大地推动中枢神经系统屏障研究。
