Department of Geriatrics, 9th People's Hospital Affiliated to School of Medicine, Shanghai Jiaotong University, Shanghai, China.
Med Sci Monit. 2011 Sep;17(9):BR248-56. doi: 10.12659/msm.881928.
The liver renin-angiotensin system (RAS) plays an important role in promoting the development of hepatic fibrogenesis. Angiotensinogen (AGT) is an important precursor in tissue RAS. This study aimed to investigate the expression and cellular source of AGT in hepatic fibrogenesis and its effect on proliferation and collagen metabolism of hepatic stellate cells.
MATERIAL/METHODS: In a rat carbon tetrachloride (CCl4)-induced liver fibrosis model the mRNA expression of AGT was determined by real-time PCR and the cellular source of AGT was determined by immunohistochemical staining. In vitro HSC-T6 cells were transfected with AGT, and the expression plasmid, AGT shRNA plasmid and negative shRNA plasmid were constructed. Real-time PCR and ELISA were applied to determine the mRNA expressions and contents of TIMP-1, TGF-β1, type I collagen and type III collagen of the cells or in the supernatants.
Compared to normal liver, the AGT and α-SMA mRNA expressions increased at the early stage of hepatic fibrosis and decreased in hepatic cirrhosis. The expressions of AGT and α-SMA mRNA were correlated with the hepatic fibrosis (r=0.915, P=0.03). Immunohistochemistry demonstrated the activated HSCs were the main source of AGT due to colocalization of AGT and α-SMA expressions. The mRNA and protein of TGF-β1, TIMP-1, type I collagen and type III collagen were markedly up-regulated.
ACEI and angiotensin II type 1 receptor antagonist (AT1RA) could attenuate the progression of hepatic fibrosis in the early stage. Direct inhibition of AGT from aHSCs may become an effective antifibrotic anti-liver fibrosis strategy.
肝脏肾素-血管紧张素系统（RAS）在促进肝纤维化发展中起重要作用。血管紧张素原（AGT）是组织 RAS 的重要前体。本研究旨在探讨肝纤维化过程中 AGT 的表达和细胞来源及其对肝星状细胞增殖和胶原代谢的影响。
材料/方法：采用四氯化碳（CCl4）诱导大鼠肝纤维化模型，实时 PCR 检测 AGT 的 mRNA 表达，免疫组化染色检测 AGT 的细胞来源。体外 HSC-T6 细胞转染 AGT，构建 AGT 表达质粒、AGT shRNA 质粒和阴性 shRNA 质粒。实时 PCR 和 ELISA 检测细胞或上清液中 TIMP-1、TGF-β1、I 型胶原和 III 型胶原的 mRNA 表达和含量。
与正常肝组织相比，肝纤维化早期 AGT 和 α-SMA 的 mRNA 表达增加，肝硬化时降低。AGT 和 α-SMA mRNA 的表达与肝纤维化相关（r=0.915，P=0.03）。免疫组化显示，活化的 HSCs 是 AGT 的主要来源，因为 AGT 与 α-SMA 的表达存在共定位。TGF-β1、TIMP-1、I 型胶原和 III 型胶原的 mRNA 和蛋白表达明显上调。
ACEI 和血管紧张素 II 型 1 受体拮抗剂（AT1RA）可抑制肝纤维化早期进展。直接抑制活化的 HSCs 中的 AGT 可能成为一种有效的抗肝纤维化策略。
