Background: Connective tissue growth factor (CTGF) belongs to a family of factors that regulate fibrogenesis and wound healing. While the significance of transforming growth factor beta (TGF-beta) in liver fibrosis is well established, the role of CTGF in fibrosing hepatopathy is still unknown.
Methods: CTGF was analyzed in 10 normal and in 16 cirrhotic liver tissue samples. Northern blot analysis was used to examine the concomitant expression of CTGF and TGF-beta1 mRNAs, and the cellular localization of CTGF mRNA was studied by in situ hybridization. For identification of myofibroblasts and activated hepatic stellate cells, alpha-smooth muscle actin (alpha-SMA) immunohistochemistry was used.
Results: Northern blot analysis showed 6.5-fold enhanced expression of CTGF mRNA and 7.8-fold enhanced expression of TGF-beta1 mRNA in liver cirrhosis in comparison with normal controls (p<0.01). By in situ hybridization, CTGF mRNA was detectable in only a few spindle cells in the portal tracts in normal liver samples. In contrast, there was strong expression of CTGF mRNA in fibroblasts and myofibroblast-like cells present in fibrous septa surrounding the cirrhotic nodules, in stellate cells, in endothelial cells and in mesenchymal cells around ductular proliferations, and in ductular epithelial cells. There was a strong correlation between CTGF mRNA and TGF-beta1 mRNA as well as the degree of fibrosis (p<0.01).
Conclusions: Overexpression of CTGF in liver cirrhosis, especially in fibroblasts/myofibroblasts and stellate cells, suggests that this novel factor may play an important role in hepatic fibrosis.