Scavenger properties of cultivated pig liver endothelial cells.
Scavenger properties of cultivated pig liver endothelial cells.
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DOI：
10.1186/1476-5926-3-4
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发表时间：
2004-08-12
期刊：
影响因子：
--
通讯作者：
Smedsrød B
中科院分区：
文献类型：
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作者：
Elvevold KH;Nedredal GI;Revhaug A;Smedsrød B
肝窦内皮细胞（LSEC）和枯否细胞构成了体内最强大的清道夫系统。由于正常的分解代谢过程，从组织中大量持续释放的各种废物大分子被LSEC清除。尽管猪肝被广泛应用于实验环境中，但猪LSEC的清除特性至今尚未研究。因此，我们研究了LSEC中五类内吞受体配体的内吞和胞内转运。5种125 I标记的分子：胶原α链、FITC-生物素-透明质酸、甘露聚糖、甲醛处理的血清白蛋白（FSA）和聚集的γ球蛋白（AGG）在培养的LSEC中被大量内吞。内吞作用分别通过胶原蛋白、透明质酸、甘露糖、清道夫或IgG Fc受体介导，通过未标记配体与标记配体竞争摄取的能力判断。采用形态脉冲追踪技术研究了细胞内运输。通过猪的颈静脉给予红色TRITC-FSA以标记LSEC溶酶体后90分钟，建立细胞培养物，并用绿色FITC标记的胶原蛋白、β-甘露聚糖和β-FSA脉冲。到10分钟时，FITC配体位于分散在整个细胞质中的小泡中，与红色溶酶体没有共定位。到2小时，FITC-配体与红色溶酶体共定位。当用FITC-AGG和TRITC-FSA一起脉冲LSEC时，在10分钟追踪后观察到两种配体的共定位。到2小时，仅观察到部分共定位; TRITC-FSA被转运至溶酶体，而FITC-AGG仅缓慢离开内体。酶活性测定结果表明，LSEC和Kupffer细胞中氨基己糖苷酶、芳基硫酸酯酶、酸性磷酸酶和酸性脂肪酶的比活力相当，而α-甘露糖苷酶和葡萄糖醛酸糖苷酶的比活力在LSEC中较高。与实质细胞相比，所有测量的酶在LSEC中显示出相当高的比活性。猪LSEC表达以下五类高容量内吞受体：清道夫受体、甘露糖受体、透明质酸受体、胶原蛋白受体和IgG Fc受体。在肝脏中，这五种受体的可溶性配体仅被LSEC内吞。此外，LSEC含有降解内吞物质所需的溶酶体酶的高比活性。我们的观察结果表明，猪LSEC具有与先前在大鼠LSEC中描述的相同的清除活性。
The liver sinusoidal endothelial cells (LSEC) and Kupffer cells constitute the most powerful scavenger system in the body. Various waste macromolecules, continuously released from tissues in large quantities as a consequence of normal catabolic processes are cleared by the LSEC. In spite of the fact that pig livers are used in a wide range of experimental settings, the scavenger properties of pig LSEC has not been investigated until now. Therefore, we studied the endocytosis and intracellular transport of ligands for the five categories of endocytic receptors in LSEC. Endocytosis of five 125I-labelled molecules: collagen α-chains, FITC-biotin-hyaluronan, mannan, formaldehyde-treated serum albumin (FSA), and aggregated gamma globulin (AGG) was substantial in cultured LSEC. The endocytosis was mediated via the collagen-, hyaluronan-, mannose-, scavenger-, or IgG Fc-receptors, respectively, as judged by the ability of unlabelled ligands to compete with labelled ligands for uptake. Intracellular transport was studied employing a morphological pulse-chase technique. Ninety minutes following administration of red TRITC-FSA via the jugular vein of pigs to tag LSEC lysosomes, cultures of the cells were established, and pulsed with green FITC-labelled collagen, -mannan, and -FSA. By 10 min, the FITC-ligands was located in small vesicles scattered throughout the cytoplasm, with no co-localization with the red lysosomes. By 2 h, the FITC-ligands co-localized with red lysosomes. When LSEC were pulsed with FITC-AGG and TRITC-FSA together, co-localization of the two ligands was observed following a 10 min chase. By 2 h, only partial co-localization was observed; TRITC-FSA was transported to lysosomes, whereas FITC-AGG only slowly left the endosomes. Enzyme assays showed that LSEC and Kupffer cells contained equal specific activities of hexosaminidase, aryl sulphates, acid phosphatase and acid lipase, whereas the specific activities of α-mannosidase, and glucuronidase were higher in LSEC. All enzymes measured showed considerably higher specific activities in LSEC compared to parenchymal cells. Pig LSEC express the five following categories of high capacity endocytic receptors: scavenger-, mannose-, hyaluronan-, collagen-, and IgG Fc-receptors. In the liver, soluble ligands for these five receptors are endocytosed exclusively by LSEC. Furthermore, LSEC contains high specific activity of lysosomal enzymes needed for degradation of endocytosed material. Our observations suggest that pig LSEC have the same clearance activity as earlier described in rat LSEC.