Hagens W I, Beljaars L, Mann D A, Wright M C, Julien B, Lotersztajn S, Reker-Smit C, Poelstra K
Department of Pharmacokinetics and Drug Delivery, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
J Pharmacol Exp Ther. 2008 Mar;324(3):902-10. doi: 10.1124/jpet.107.132290. Epub 2007 Dec 12.
Liver fibrosis is associated with proliferation of hepatic stellate cells (HSCs) and their transformation into myofibroblastic cells that synthesize scar tissue. Several studies indicate that induction of apoptosis in myofibroblastic cells may prevent fibrogenesis. Gliotoxin (GTX) was found to induce apoptosis of hepatic cells and caused regression of liver fibrosis. However, the use of apoptosis-inducing drugs may be limited due to lack of cell specificity, with a risk of severe adverse effects. In previous studies, we found that mannose-6-phosphate-modified human serum albumin (M6P-HSA) selectively accumulated in liver fibrogenic cells. The aim of this study therefore was to couple GTX to M6P-HSA and test its pharmacological effects in vitro and in rats with liver fibrosis. The conjugate GTX-M6P-HSA bound specifically to HSCs and reduced their viability. Apoptosis was induced in cultures of human hepatic myofibroblasts (hMFs) and in liver slices obtained from rats with liver fibrosis. In vivo treatment with GTX or GTX-M6P-HSA in bile duct ligated rats revealed a significant decrease in alpha-smooth muscle actin mRNA levels and a reduced staining for this HSC marker in fibrotic livers. In addition, although GTX also affected hepatocytes, GTX-M6P-HSA did not significantly affect other liver cells. In conclusion, we developed an HSC-specific compound that induced apoptosis in human hMFs, rat HSCs, and in fibrotic liver slices. In vivo, both GTX and GTX-M6P-HSA attenuated the number of activated HSCs, but GTX also affected hepatocytes. This study shows that cell-selective delivery of the apoptosis-inducing agent GTX is feasible in fibrotic livers.
肝纤维化与肝星状细胞（HSCs）的增殖及其向合成瘢痕组织的肌成纤维细胞转化有关。多项研究表明，诱导肌成纤维细胞凋亡可能预防纤维化形成。已发现gliotoxin（GTX）可诱导肝细胞凋亡并导致肝纤维化消退。然而，由于缺乏细胞特异性且存在严重不良反应风险，诱导凋亡药物的使用可能受到限制。在先前的研究中，我们发现甘露糖-6-磷酸修饰的人血清白蛋白（M6P-HSA）选择性积聚在肝纤维化细胞中。因此，本研究的目的是将GTX与M6P-HSA偶联，并在体外和肝纤维化大鼠中测试其药理作用。偶联物GTX-M6P-HSA特异性结合HSCs并降低其活力。在人肝肌成纤维细胞（hMFs）培养物和肝纤维化大鼠的肝切片中诱导了凋亡。在胆管结扎大鼠中用GTX或GTX-M6P-HSA进行体内治疗显示，α-平滑肌肌动蛋白mRNA水平显著降低，纤维化肝脏中该HSC标志物的染色减少。此外，尽管GTX也影响肝细胞，但GTX-M6P-HSA对其他肝细胞没有显著影响。总之，我们开发了一种HSC特异性化合物，该化合物可在人hMFs、大鼠HSCs和纤维化肝切片中诱导凋亡。在体内，GTX和GTX-M6P-HSA均减少了活化HSCs的数量，但GTX也影响肝细胞。本研究表明，在纤维化肝脏中细胞选择性递送凋亡诱导剂GTX是可行的。
