Comparison between the antifibrotic effects of adeno-associated virus and lentivirus carrying small interfering RNA of TIMP-1 in rat liver fibrosis

Objective To construct recombinant adeno-associated virus and lentivirus carrying siRNA of TIMP-1 and to investigate their antifibrotic effects on CCl4-induced liver fibrosis in rats.Methods One pair of siRNA which could effectively inhibit expression of the TIMP-1 gene in HSC-T6 was screened and cloned into AAV vector and lentiviral vector to construct the recombinant AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1.AAV/EGFP and Lenti/EGFP as negative control were also obtained.Fifty-eight male Wistar rats were randomly divided into six groups: control group(n=8),CCl4 group,AAV/EGFP,Lenti/EGFP,AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 groups(all n=10).After the administration of CCl4 for four weeks,liver samples were collected for the immunohistochemical staining and detection of TIMP-1 expression.Results Livers from the control rats showed normal lobular structure around vessels(HE and Masson staining).In contrast,livers from the model,AAV/EGFP and Lenti/EGFP groups showed severe fibrosis,including septal fibrosis,extensive bridging,and fatty degeneration.The expressions of TIMP-1 mRNA and protein were also elevated in the livers from these groups.Compared with the fibrosis model group,the AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 groups showed good preservation of liver lobular architecture and only mild bridging fibrosis,accompanied by decreased expression of TIMP-1 mRNA and protein.Semi-quantitative analysis of the fibrosis stage indicated that most rats in the model,AAV/EGFP and Lenti/EGFP groups were of S3 and S4(80%),while 20% of the rats were of S5.In contrast,most rats(90%) in the AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 groups were of stages S2 and S3,with only one rat of S4.There was no significant difference between these recombinant virus therapy groups.Conclusions Both AAV/siRNA-TIMP-1 and Lenti/siRNA-TIMP-1 can suppress the expression of TIMP-1 in rat fibrotic liver,playing an effective antifibrotic role in the rat liver.