Downregulation of matrix and β-PDGF receptor gene expression by anti-TGFβ antibody in rat hepatic stellate cells during experimental liver injury

Excess matrix in hepatic fibrosis results from both fibrogenic stimulation of stellate cells by TGFβ1 and cell proliferation due to induction of β-platelet derived growth factor receptor (β-PDGFR). In this paper, treatment of culture-activated rat stellate cells with anti-TGFβ inhibited collagen and fibronectin mRNA expression by 82 and 58%, respectively, versus control cells. In vivo, anti-TGFβ inhibited collagen I gene expression by 86% in stellate cells isolated from rats treated with CC14 compared with control antibody. In contrast to stellate cells, anti-TGFβ had no effect on collagen I gene expression in isolated sinusoidal endothelial cells. Anti-TGFβ administered in vivo to rats with liver injury also reduced expression of stellate cell β-PDGFR mRNA to that of control animals. Anti-TGFβ antibody had no effect on the histologic appearance of the tissue. These data support a role for TGFβ in stellate cell matrix expression and provide evidence for transmodulation of PDGF receptor by TGFβ in vivo. However, inhibition of TGFβ alone may not be adequate to attenuate severe hepatic injury and fibrosis.