De Bleser P J, Scott C D, Niki T, Xu G, Wisse E, Geerts A
Laboratory for Cell Biology and Histology, Free University Brussels, Belgium.
Hepatology. 1996 Jun;23(6):1530-7. doi: 10.1002/hep.510230633.
The liver is reported to be the main source of soluble insulin-like growth factor-II/mannose 6-phosphate (IGF-II/M6P) receptor in adults. In view of the role of this receptor in the activation of transforming growth factor beta (TGF-beta) during hepatic fibrogenesis, we have investigated the correlation between serum levels and tissue expression of the receptor during acute CCl4 intoxication of the rat. Sixteen hours after CCl4, injection, the level of the soluble receptor in serum, as measured by radioimmunoassay (RIA), increased threefold. At 24 hours, values almost returned to normal, but increased again by twofold at 48 hours. By 96 hours, nearly normal values were obtained. Northern blot analysis showed peaks in tissue IGF-II/M6P receptor messenger RNA (mRNA) levels at 24 hours and at 48 hours. In normal liver, immunostaining for IGF-II/M6P receptor showed weak positivity in parenchymal cells. CCl4-induced hydropic changes appeared in centrilobular parenchymal cells (PCs) at 8 hours. These changes extended to the midzonal region at 16 hours. Hydropic cells were devoid of receptor staining. The hydropic wave became extinct at 32 hours. At 48 hours, we observed a collapse of PCs in the centrilobular zone, coinciding with strongly positive staining for IGF-II/M6P receptor in fat-storing cells (FSCs), identified by dual IGF-II/M6P receptor and desmin immunostaining. Between 48 and 72 hours, the liver gradually regained its normal appearance. As shown by Western blotting, in vitro differentiated FSCs released soluble receptor in the medium. Northern blot analysis showed this release to be preceded by an increased receptor-mRNA expression, whereas immunostaining showed an increase of intracellular receptor. In conclusion, we have shown that acute CCl4 intoxication induces two peaks in serum levels of soluble receptor. While the first peak at 16 hours coincides with the loss of receptor-staining in hydropically damaged PCs, the second peak at 48 hours is paralleled by an increase in positive staining in FSCs and tissue mRNA level. Differentiated FSCs shed soluble receptor in vitro. As a consequence, these cells might contribute to the serum levels of soluble receptor in vivo. These results indicate that measuring serum soluble IGF-II/M6P receptor might useful in the diagnosis of early acute liver damage.
据报道，肝脏是成年人可溶性胰岛素样生长因子-II/甘露糖6-磷酸（IGF-II/M6P）受体的主要来源。鉴于该受体在肝纤维化形成过程中对转化生长因子β（TGF-β）激活的作用，我们研究了大鼠急性四氯化碳中毒期间血清水平与该受体组织表达之间的相关性。四氯化碳注射16小时后，通过放射免疫分析（RIA）测得的血清中可溶性受体水平增加了两倍。24小时时，数值几乎恢复正常，但在48小时时又增加了一倍。到96小时时，获得了接近正常的数值。Northern印迹分析显示，组织IGF-II/M6P受体信使核糖核酸（mRNA）水平在24小时和48小时出现峰值。在正常肝脏中，IGF-II/M6P受体免疫染色显示实质细胞呈弱阳性。四氯化碳诱导的水样变性在8小时出现在小叶中央实质细胞（PCs）中。这些变化在16小时扩展到中区区域。水样变性细胞缺乏受体染色。水样变性波在32小时消失。在48小时时，我们观察到小叶中央区的PCs塌陷，同时通过IGF-II/M6P受体和结蛋白双重免疫染色鉴定的贮脂细胞（FSCs）中IGF-II/M6P受体呈强阳性染色。在48至72小时之间，肝脏逐渐恢复其正常外观。如Western印迹所示，体外分化的FSCs在培养基中释放可溶性受体。Northern印迹分析表明，这种释放之前受体-mRNA表达增加，而免疫染色显示细胞内受体增加。总之，我们表明急性四氯化碳中毒诱导血清可溶性受体水平出现两个峰值。虽然16小时时的第一个峰值与水样变性受损PCs中受体染色的丧失一致，但48小时时的第二个峰值与FSCs中阳性染色增加和组织mRNA水平增加平行。分化的FSCs在体外释放可溶性受体。因此，这些细胞可能对体内可溶性受体的血清水平有贡献。这些结果表明，检测血清可溶性IGF-II/M6P受体可能有助于早期急性肝损伤的诊断。
