rAAV-mediated stable expression of heme oxygenase-1 in stellate cells: A new approach to attenuate liver fibrosis in rats

✍ Scribed by Tung-Yu Tsui; Chi-Keung Lau; Jian Ma; Xiaobing Wu; Yan-Qing Wang; Stefan Farkas; Ruian Xu; Hans J. Schlitt; Sheung-Tat Fan

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 358 KB
• Volume: 42
• Category: Article
• ISSN: 0270-9139
• DOI: 10.1002/hep.20803

✦ Synopsis

Liver fibrosis is the consequence of activation of hepatic stellate cells mediated by persistent or recurrent liver injury, where oxidative stress or inflammatory response resulting from immune cells and cytokines are involved. Targeting of hepatic stellate cells could be an important strategy for the therapy of liver fibrosis. In this study, we showed a tropism of recombinant adeno-associated virus (rAAV, serotype 2) with high efficiency in transduction of a homeostatic gene, heme oxygenase-1 (HO-1), to activated stellate cells. The binding of rAAVs to stellate cells increased significantly after serum-stimulated activation compared with quiescent status. Portal injection of rAAVs to normal or carbon tetrachloride (CCl 4 )induced liver fibrosis showed a distinct distribution of rAAV binding. The majority of injected rAAVs bound to the cells in fibrotic areas that were associated with higher expression levels of fibroblast growth factor receptor-1␣ at 2 hours after administration. Isolation of different types of cells from CCl 4 -induced fibrotic livers showed predominant expression of transgene in stellate cells after rAAV/HO-1 administration on day 3 and remained stable for 12 weeks. In addition, HO-1-transduced stellate cells showed reduced transcript levels of type 1 collagen and impaired proliferative ability compared with controls. With this approach, the severity of established micronodular cirrhosis was markedly reduced. In conclusion, these findings suggest a new approach for the treatment of liver fibrosis using adenoassociated virus-mediated gene transfer. (HEPATOLOGY 2005;42:335-342.)

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irrhosis is the end result of chronic liver injury, formation of fibrotic tissues, and regeneration of hepatocytes. 1,2 Other than liver transplantation, which treats patients with end-stage liver failure, no available therapy can effectively interfere with the progression of cirrhosis. Under various disease-related conditions, persistence of recurrent hepatocellular injury leads to a wound-healing process in which oxidative stress, inflammatory response mediated by immune cells and/or cytokines, and activation of hepatic stellate cells (HSCs) contribute to the cascade of fibrogenesis. Heme oxygenase-1 (HO-1) is an inducible protein that responds to a wide range of stimuli. 11 It cleaves pro-oxidant heme into equimolar amounts of carbon monoxide, biliverdin/bilirubin, and free iron. Although expression of HO-1 in the liver is restricted to a subpopulation of Kupffer cells, 13 the gene is inducible in both parenchymal and particularly nonparenchymal liver cells under stress conditions. 14 Protective effects of enhanced HO enzymatic activity-probably through its products-have been reported in various disease-related models, 15-18 but the functional role as well as the therapeutic potential of HO-1 in liver fibrogenesis is still unknown. Importantly, no evidence is available on whether HO-1 can be targeted for the treatment of liver fibrosis. In this study, we demonstrated for the first time the advantages of using adenoassociated viral vector, a nonpathogenic single-stranded DNA virus in wild-type, for HSC-targeted gene transfer