Brief Article
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Nov 21, 2013; 19(43): 7778-7787
Published online Nov 21, 2013. doi: 10.3748/wjg.v19.i43.7778
Amelioration of carbon tetrachloride-induced cirrhosis and portal hypertension in rat using adenoviral gene transfer of Akt
Gang Deng, Xiang-Jun Huang, Hong-Wu Luo, Fei-Zhou Huang, Xun-Yang Liu, Yong-Heng Wang
Gang Deng, Xiang-Jun Huang, Hong-Wu Luo, Fei-Zhou Huang, Xun-Yang Liu, Yong-Heng Wang, Department of Hepatobiliary and Pancreatic Surgery, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
Author contributions: Huang FZ, Liu XY and Wang YH participated in research design and other authors collectively contributed to the performance of laboratory measurements; Deng G, Huang XJ and Huang FZ were involved in data collection and analysis; and Deng G, Huang XJ and Luo HW wrote the manuscript.
Correspondence to: Hong-Wu Luo, MD, Department of Hepatobiliary and Pancreatic Surgery, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China. luohongwuzny@sina.com
Telephone: +86-731-88618230 Fax: +86-731-88618030
Received: June 30, 2013
Revised: August 28, 2013
Accepted: September 15, 2013
Published online: November 21, 2013
Processing time: 170 Days and 10.3 Hours
Abstract

AIM: To investigate whether a virus constitutively expressing active Akt is useful to prevent cirrhosis induced by carbon tetrachloride (CCl4).

METHODS: Using cre-loxp technique, we created an Ad-myr-HA-Akt virus, in which Akt is labeled by a HA tag and its expression is driven by myr promoter. Further, through measuring enzyme levels and histological structure, we determined the efficacy of this Ad-myr-HA-Akt virus in inhibiting the development of cirrhosis induced by CCl4 in rats. Lastly, using western blotting, we examined the expression levels and/or phosphorylation status of Akt, apoptotic mediators, endothelial nitric oxide synthase (eNOS), and markers for hepatic stellate cells activation to understand the underlying mechanisms of protective role of this virus.

RESULTS: The Ad-myr-HA-Akt virus was confirmed using polymerase chain reaction amplification of inserted Akt gene and sequencing for full length of inserted fragment, which was consistent with the sequence reported in the GenBank. The concentrations of Ad-myr-HA-Akt and adenoviral enhanced green fluorescent protein (Ad-EGFP) virus used in the current study were 5.5 × 1011 vp/mL. The portal vein diameter, peak velocity of blood flow, portal blood flow and congestion index were significantly increased in untreated, saline and Ad-EGFP cirrhosis groups when compared to normal control after the virus was introduced to animal through tail veil injection. In contrast, these parameters in the Akt cirrhosis group were comparable to normal control group. Compared to the normal control, the liver function (Alanine aminotransferase, Aspartate aminotransferase and Albumin) was significantly impaired in the untreated, saline and Ad-EGFP cirrhosis groups. The Akt cirrhosis group showed significant improvement of liver function when compared to the untreated, saline and Ad-EGFP cirrhosis groups. The Hyp level and portal vein pressure in Akt cirrhosis groups were also significantly lower than other cirrhosis groups. The results of HE and Van Gieson staining indicated that Akt group has better preservation of histological structure and less fibrosis than other cirrhosis groups. The percentage of apoptotic cell was greatly less in Akt cirrhosis group than in other cirrhosis groups. Akt group showed positive HA tag and an increased level of phosphorylated Akt as well as decreased levels of Fas. In contrast, Caspase-3 and Caspase-9 levels in Akt group were significantly lower than other cirrhosis groups. Noticeable decrease of DR5 and α-SMA and increase of phosphorylated eNOS were observed in the Akt group when compared to other cirrhosis groups. The NO level in liver was significantly higher in Akt group than other cirrhosis groups, which was consistent with the level of phosphorylated eNOS in these groups.

CONCLUSION: This study suggest that Ad-myr-HA-Akt virus is a useful tool to prevent CCl4-induced cirrhosis in rat model and Akt pathway may be a therapeutic target for human cirrhosis.

Keywords: Adenovirus; Akt; Gene transfer; Apoptosis; Cirrhosis; Carbon tetrachloride; Rat

Core tip: In the present study, we have demonstrated for the first time that Ad-myr-HA-Akt virus was a useful tool to prevent carbon tetrachloride-induced cirrhosis in rat model. Our data obtained at different levels, from function to histological changes, apoptosis rate of hepatocytes, activation of hepatic stellate cells, deposition of collagen, portal vein pressure and NO level, which were all consistently and collectively supported the hypothesis that introduction of Ad-myr-HA-Akt virus inhibits the development of cirrhosis.