Figure 1.

Upregulation of hepatic cathepsin L (CTSL) and cathepsin B (CTSB) expression in experimental liver fibrosis. Mice were intraperitoneally injected with carbon tetrachloride (CCl₄) or vehicle (olive oil) twice a week for 10 weeks. Hepatic CTSL and CTSB levels were evaluated by real-time PCR and immunohistochemistry. (a) Relative CTSL mRNA expression was significantly increased in the liver of CCl₄-treated mice while CTSB levels were comparable. (b, c) Representative pictures of CTSL and CTSB immunostaining in control and CCl₄-treated livers. Liver section from control exhibits granular CTSL immunostaining pattern while in CCl₄-treated mice diffuse and strong cytoplasmic staining is evident in the hepatocytes, bile duct epithelium, fibroblasts, and Kupffer cells as indicated by arrows (Original magnification, × 200). (d) Quantification of immunostained CTSL and CTSB revealed overexpression of CTSL in the liver of CCl₄-treated mice (values are mean±s.e.m., n=6), *P≤0.05 compared with controls. (e, f) Temporal expression of hepatic CTSL and CTSB transcript levels were quantified in Abcb4−/− mice and their wild-type littermates. Compared with wild-type controls, CTSL and CTSB expression were significantly higher in Abcb4−/− at 4 weeks but gradually decreased to the basal levels by 16 weeks (mean±s.e.m., n=at least 7 mice in each group). *P≤0.05 compared with wild-type controls.