Uptake and transport of high-density lipoprotein (HDL) and HDL-associated α-tocopherol by an in vitro blood-brain barrier model
Uptake and transport of high-density lipoprotein (HDL) and HDL-associated α-tocopherol by an in vitro blood-brain barrier model
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DOI：
10.1111/j.1471-4159.2004.02373.x
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发表时间：
2004-05-01
影响因子：
4.7
通讯作者：
Sattler, W
中科院分区：
文献类型：
--
作者：
Balazs, Z;Panzenboeck, U;Sattler, W
本研究的目的是研究有助于高密度脂蛋白（HDL）和HDL相关α-生育酚（alphaTocH）穿过血脑屏障（BBB）体外模型的摄取和转胞吞的途径。在原代猪脑毛细血管内皮细胞中，HDL相关的alphaTocH被10倍过量的HDL全颗粒摄取，表明有效的选择性摄取，这是一种由清道夫受体B类I型（SR-BI）介导的途径。SR-BI在脑毛细血管内皮细胞的小窝中表达，几乎只在顶膜表达。用甲基-β-环糊精（CDX）破坏小窝导致SR-BI（错误）分选至基底外侧膜。猪脑冷冻切片的免疫组织化学显示SR-BI在脑毛细血管内皮细胞和可能的星形胶质细胞终足上表达。脑毛细血管内皮细胞摄取的HDL相关[C-14]alphaTocH在含有大部分细胞小窝蛋白-1（主要小窝相关蛋白）的蔗糖梯度级分中回收。在使用富含alphaTocH的HDL的传质研究期间，约50%的细胞alphaTocH与大量细胞小窝蛋白-1和SR-BI一起回收。外排实验表明，大量的细胞相关的[C-14]alphaTocH可以被动员到培养基中。此外，HDL全颗粒和HDL相关α TocH的顶侧至基底侧转运是饱和的。本研究的结果表明，部分脑载脂蛋白A-1和alphaTocH来源于血浆HDL跨血脑屏障的转胞吞，并且位于小窝的SR-BI促进血脑屏障中HDL相关alphaTocH的选择性摄取。
The present study aimed to investigate pathways that contribute to uptake and transcytosis of high-density lipoproteins (HDLs) and HDL-associated alpha-tocopherol (alphaTocH) across an in vitro model of the blood-brain barrier (BBB). In primary porcine brain capillary endothelial cells HDL-associated alphaTocH was taken up in 10-fold excess of HDL holoparticles, indicating efficient selective uptake, a pathway mediated by scavenger receptor class B, type I (SR-BI). SR-BI was present in caveolae of brain capillary endothelial cells and expressed almost exclusively at the apical membrane. Disruption of caveolae with methyl-beta-cyclodextrin (CDX) resulted in (mis)sorting of SR-BI to the basolateral membrane. Immunohistochemistry of porcine brain cryosections revealed SR-BI expression on brain capillary endothelial cells and presumably astrocytic endfeet. HDL-associated [C-14]alphaTocH taken up by brain capillary endothelial cells was recovered in sucrose gradient fractions containing the majority of cellular caveolin-1, the major caveolae-associated protein. During mass transfer studies using alphaTocH-enriched HDL, approximately 50% of cellular alphaTocH was recovered with the bulk of cellular caveolin-1 and SR-BI. Efflux experiments revealed that a substantial amount of cell-associated [C-14]alphaTocH could be mobilized into the culture medium. In addition, apical-to-basolateral transport of HDL holoparticles and HDL-associated alphaTocH was saturable. Results from the present study suggest that part of cerebral apolipoprotein A-1 and alphaTocH originates from plasma HDL transcytosed across the BBB and that caveolae-located SR-BI facilitates selective uptake of HDL-associated alphaTocH at the BBB.