Objective: To design and synthesize small interfering RNA (siRNA) targeting connective tissue growth factor (CTGF) and to investigate its effect on liver fibrosis.
Methods: The interference sequence of CTGF was designed and synthesized. Rat hepatic fibrosis model was induced by intraperitoneal injection of 40 % CCl4(3 ml/kg). Thirty male rats were randomly divided into 5 groups: in normal control and model groups rats received tail vein injection of normal saline every 3 days for 8 consecutive weeks; in preventive group rats received tail vein injection of CTGF siRNA (0.1 mg/kg) every 3 days for 8 weeks; in 2-w treatment group CTGF siRNA was given for 6 weeks starting from two weeks after CCl4 injection; in 4-w treatment group CTGF siRNA was given for 4 weeks starting 4 weeks after CCl4 injection. The serum and hepatic tissue samples were harvested 3 days after the last CCl4 injection. Hepatic fibrosis indices were measured. Expression of CTGF mRNA and protein in the liver was evaluated by RT-PCR and Western blot, respectively. Fibrosis in rat liver was analyzed by Masson staining.
Results: Compared with model group (0.544 0.019), the expression of CTGF mRNA and protein in liver of both preventive(0.105 ± 0.003) and 2-w treatment groups (0.190 ± 0.006) were markedly down-regulated (P<0.05). Inflammation, necrosis and fibrosis in hepatic tissue were significantly attenuated. In addition, the serum ration of liver fibrosis indices was greatly reduced(P<0.05). Compared with preventive and 2-w treatment groups, the expression of CTGF mRNA and protein in liver in 4 weeks of treatment group were up-regulated (P<0.05); inflammation, necrosis and fibrosis in hepatic tissue were relative increased; and the serum concentrations of liver fibrosis indices were relatively higher (P<0.05).
Conclusion: The highly effective CTGF siRNA has been successfully synthesized, which can inhibit CTGF expression in liver, prevent hepatic fibrosis and its progress in rats.