Unconjugated bilirubin elevation impairs the function and expression of breast cancer resistance protein (BCRP) at the blood-brain barrier in bile duct-ligated rats
Unconjugated bilirubin elevation impairs the function and expression of breast cancer resistance protein (BCRP) at the blood-brain barrier in bile duct-ligated rats
复制标题
非结合胆红素升高损害胆管结扎大鼠血脑屏障的乳腺癌抵抗蛋白（BCRP）的功能和表达
DOI：
10.1038/aps.2016.25
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发表时间：
2016
影响因子：
8.2
通讯作者：
Liu Xiao-dong
中科院分区：
文献类型：
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作者：
Xu Ping;Ling Zhao-li;Zhang Ji;Li Ying;Shu Nan;Zhong Ze-yu;Chen Yang;Di Xin-yu;Wang Zhong-jian;Liu Li;Liu Xiao-dong
目的：肝衰竭与血脑屏障 (BBB) 外排转运蛋白的稳态失调有关，从而导致肝性脑病。在本研究中，我们检测了乳腺癌抵抗蛋白（BCRP）（BBB的主要外排转运蛋白）在大鼠肝衰竭期间是否发生改变。方法：对大鼠进行胆管结扎（BDL）手术，然后在第3、7和14天静脉注射哌唑嗪后处死。收集了大脑和血液样本。通过脑与血浆哌唑嗪浓度比评估 BBB 的 BCRP 功能；脑组织中的伊文思蓝外渗被用作血脑屏障完整性的指标。检测脑组织中BCRP蛋白水平。体外测试了人脑微血管内皮细胞（HCMEC/D3）和表达人BCRP的Madin-Darby犬肾细胞（MDCK-BCRP）。另外，通过静脉注射未结合胆红素（UCB）诱导大鼠出现高胆红素血症（HB）。结果：BDL大鼠从第3天到第14天肝功能和HB进行性下降。在BDL大鼠的脑组织中，BCRP的功能和蛋白水平逐渐降低，而BBB完整性完好。此外，BDL 大鼠血清显着降低 HCMEC/D3 细胞中的 BCRP 功能和蛋白水平。在测试的BDL大鼠血清中异常改变的成分中，UCB（10、25μmol/L）剂量依赖性地抑制HCMEC/D3细胞中的BCRP功能和蛋白水平，而3种胆汁酸（CDCA、UDCA和DCA）没有影响。在 MDCK-BCRP 细胞和 HB 大鼠的大脑中也获得了类似的结果。相关分析显示，BDL大鼠和HB大鼠脑组织以及体外测试的两种细胞中UCB水平与BCRP表达呈负相关。结论：BDL大鼠UCB升高会损害BBB的功能和BCRP表达，从而导致肝性脑病。
Aim:Liver failure is associated with dyshomeostasis of efflux transporters at the blood-brain barrier (BBB), which contributes to hepatic encephalopathy. In this study we examined whether breast cancer resistance protein (BCRP), a major efflux transporter at the BBB, was altered during liver failure in rats.Methods:Rats underwent bile duct ligation (BDL) surgery, and then were sacrificed after intravenous injection of prazosin on d3, d7 and d14. The brains and blood samples were collected. BCRP function at the BBB was assessed by the brain-to-plasma prazosin concentration ratio; Evans Blue extravasation in the brain tissues was used as an indicator of BBB integrity. The protein levels of BCRP in the brain tissues were detected. Human cerebral microvessel endothelial cells (HCMEC/D3) and Madin-Darby canine kidney cells expressing human BCRP (MDCK-BCRP) were tested in vitro. In addition, hyperbilirubinemia (HB) was induced in rats by intravenous injection of unconjugated bilirubin (UCB).Results:BDL rats exhibited progressive decline of liver function and HB from d3 to d14. In the brain tissues of BDL rats, both the function and protein levels of BCRP were progressively decreased, whereas the BBB integrity was intact. Furthermore, BDL rat serum significantly decreased BCRP function and protein levels in HCMEC/D3 cells. Among the abnormally altered components in BDL rat serum tested, UCB (10, 25 μmol/L) dose-dependently inhibit BCRP function and protein levels in HCMEC/D3 cells, whereas 3 bile acids (CDCA, UDCA and DCA) had no effect. Similar results were obtained in MDCK-BCRP cells and in the brains of HB rats. Correlation analysis revealed that UCB levels were negatively correlated with BCRP expression in the brain tissues of BDL rats and HB rats as well as in two types of cells tested in vitro.Conclusion:UCB elevation in BDL rats impairs the function and expression of BCRP at the BBB, thus contributing to hepatic encephalopathy.