Research of small interfering RNA targeting connective tissue growth factor in prevention and therapy of rats liver fibrosis

Objective To explore whether small interfering RNA (siRNA) targeting connective tissue growth factor (CTGF) can inhibit CTGF gene expression and prevent and treat hepatic fibrosis occurrence. Methods 30 male rats were divided into 5 groups randomly, and 6 rats in each group. Rats received intraperitoneally injection of 40% CCl4 together with tail vein injection of saline every 3 days for 8 weeks were served as model group; CCl4 together with tail vein delivery of siRNA as preventive group; CCl4 for 2 weeks followed by CCl4 and CTGF siRNA for 6 weeks as early treatment group; CCl4 for 4 weeks followed by CCl4 and CTGF siRNA for 4 weeks as advanced treatment group, and only tail vein injection of saline as control group. 3 days after the last CCl4 injection, the serum and hepatic tissue from rats were harvested. Serum transaminase, albumin, total bilirubin and hepatic fibrosis indices were measured. Expression of CTGF mRNA and protein in rats liver were evaluated by RT-PCR and Western blot, respectively. Inflammation and fibrosis in rats liver were analyzed by hematoxylin and eosin(HE). Results Compared with the model group, the liver function (ALT,AST, albumin, TBil), fibrosis in hepatic tissue(hyaluronic acid, laminin, human procollagen type Ⅲ , type Ⅳ collagen) and the expression of CTGF mRNA and protein in preventive, early treatment and advanced treatment groups were markedly down-regulated(F = 8.946-171.079, P ＜ 0.05); inflammation, necrosis and fibrosis in hepatic tissue were also relative down-regulated. Compared with preventive and early treatment groups, the expression of CTGF mRNA and protein in liver in advanced treatment group were up-regulated(F = 9.075-1526.644, P ＜ 0.05). Inflammation, necrosis and fibrosis in hepatic tissue increased. Conclusions Tail vein delivery of CTGF siRNA can significantly inhibit CTGF expression in rats liver, and prevent rats hepatic fibrosis effectively. The more earlier for injection, the more to prevent the progress of liver fibrosis effectively, the therapeutic effect for advanced liver fibrosis suggests siRNA targeting CTGF treatment of liver fibrosis can become a new target. Key words: RNA, small interferon;  Connective tissue growth factor;  Liver fibrosis