Abstract

Liver fibrosis usually progresses to liver cirrhosis and even hepatocellular carcinoma. Since activated hepatic stellate cells (aHSCs) are responsible for liver fibrosis, reducing the quantity of aHSCs was considered the essential strategy for clinical antihepatofibrotic therapy. Due to the overexpression of TRAIL receptor 2 (DR5) in aHSCs, human TNF-related apoptosis-inducing ligand (hTRAIL) that could induce aHSCs apoptosis might be feasible for antihepatofibrotic therapy. However, the in vivo aHSCs-apoptosis-induction of hTRAIL is limited by its poor cell-targeting and a short half-life. In this study, we found that platelet-derived growth factor receptor β (PDGFRβ) was co-expressed with DR5 in aHSCs. And the Z_PDGFRβ affibody with high affinity for PDGFRβ could bind aHSCs and, thus, accumulate in the fibrotic liver. Z_PDGFRβ was fused to hTRAIL to produce the fusion protein Z-hTRAIL. Compared to hTRAIL, Z-hTRAIL showed greater in vitro cell binding and apoptosis-induction in aHSCs. In addition, Z-hTRAIL induced apoptosis of aHSCs but spared other normal liver cells. In vivo, Z-hTRAIL accumulated preferentially in fibrotic livers and exerted greater effects than hTRAIL in inducing aHSCs apoptosis and reducing extracellular matrix (ECM) deposition. These results demonstrated that the antihepatofibrotic effect of hTRAIL was improved by PDGFRβ-targeted delivery. To enhance its pharmacokinetics, Z-hTRAIL was modified with 10 kDa polyethylene glycol (PEG), which significantly (30–40 times) prolonged its half-life. The PEGylated long-acting Z-hTRAIL was more potent than the native Z-hTRAIL in regressing liver fibrosis. These results suggest that the aHSC-targeting and long-acting Z-hTRAIL might serve as a novel tool for antihepatofibrotic therapy.

中文翻译：

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靶向PDGFRβ的TRAIL特异性诱导活化的肝星状细胞凋亡并改善肝纤维化

摘要

肝纤维化通常会发展为肝硬化，甚至肝细胞癌。由于活化的肝星状细胞（aHSC）负责肝纤维化，因此减少aHSC的数量被认为是临床抗肝纤维化治疗的基本策略。由于aHSCs中TRAIL受体2（DR5）的过表达，可能诱导aHSCs细胞凋亡的人TNF相关凋亡诱导配体（hTRAIL）对于抗肝纤维化治疗可能是可行的。但是，hTRAIL的体内aHSCs凋亡诱导受到其细胞靶向性差和半衰期短的限制。在这项研究中，我们发现血小板衍生的生长因子受体β（PDGFRβ）与DR5在aHSCs中共表达。和Z _PDGFRβ对PDGFRβ具有高亲和力的亲和体可以结合aHSC，因此在纤维化肝脏中积累。ž _PDGFRβ将其与hTRAIL融合以产生融合蛋白Z-hTRAIL。与hTRAIL相比，Z-hTRAIL在aHSC中显示出更大的体外细胞结合和凋亡诱导作用。此外，Z-hTRAIL诱导了aHSC的凋亡，但幸免了其他正常肝细胞。在体内，Z-hTRAIL在肝纤维化肝脏中优先积累，在诱导aHSC凋亡和减少细胞外基质（ECM）沉积方面比hTRAIL发挥更大的作用。这些结果表明，通过PDGFRβ-靶向递送改善了hTRAIL的抗肝纤维化作用。为了增强其药代动力学，Z-hTRAIL用10 kDa聚乙二醇（PEG）进行了修饰，这可以显着（30–40倍）延长其半衰期。聚乙二醇化的长效Z-hTRAIL在降解肝纤维化方面比天然Z-hTRAIL更有效。