1. ¹Applied Immunobiology and Transplantation Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, University of Newcastle, Newcastle upon Tyne, UK
2. ²Liver Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, University of Newcastle, Newcastle upon Tyne, UK
3. ³Bio-Imaging Unit, Institute of Cellular Medicine, Faculty of Medical Sciences, University of Newcastle, Newcastle upon Tyne, UK

Correspondence: Dr H Robertson, PhD, Institute of Cellular Medicine, University of Newcastle, William Leech Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK. E-mail: helen.robertson@ncl.ac.uk

^*These authors contributed equally to this work.

Received 11 July 2007; Revised 26 October 2007; Accepted 26 October 2007; Published online 3 December 2007.

Abstract

The relationship between bile duct damage and portal fibrosis in chronic liver diseases remains unclear. This study was designed to show whether human intrahepatic biliary epithelial cells can undergo epithelial–mesenchymal cell transition, thereby directly contributing to fibrogenesis. Primary human cholangiocytes were stimulated with transforming growth factor- (TGF) or TGF-presenting T cells and examined for evidence of transition to a mesenchymal phenotype. Liver sections were labelled to detect antigens associated with biliary epithelial cells (cytokeratin 7 and 19 and E-cadherin), T cells (CD8), epithelial–mesenchymal transition (S100A4, vimentin and matrix metalloproteinase-2 (MMP-2)), myofibroblasts (-smooth muscle actin) and intracellular signal-transduction mediated by phosphorylated (p)Smad 2/3; in situ hybridisation was performed to detect mRNA encoding TGF and S100A4. Stimulation of cultured cells with TGF induced the expression of pSmad2/3, S100A4 and -smooth muscle actin; these cells became highly motile. Although normal bile ducts expressed ALK5 (TGF RI), low levels of TGF mRNA and nuclear pSmad2/3, they did not express S100A4, vimentin or MMP-2. However, TGF mRNA and nuclear pSmad2/3 were strongly expressed in damaged ducts, which also expressed S100A4, vimentin and MMP-2. Fibroblast-like cells which expressed S100A4 were present around many damaged bile ducts. Cells in the 'ductular reaction' expressed both epithelial and mesenchymal markers together with high levels of TGF mRNA and pSmad2/3. In conclusion, the cells forming small- and medium-sized bile ducts and the ductular reaction undergo EMT during chronic liver diseases, resulting in the formation of invasive fibroblasts; this process may be driven by a response to local TGF, possibly presented by infiltrating T cells.