T Cell-mediated biliary epithelial-to-mesenchymal transition in liver allograft rejection

✍ Scribed by Karolina A. Rygiel; Helen Robertson; Joseph D. P. Willet; John G. Brain; Alastair D. Burt; David E. J. Jones; John A. Kirby

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 587 KB
• Volume: 16
• Category: Article
• ISSN: 1527-6465
• DOI: 10.1002/lt.22029

✦ Synopsis

Loss of bile duct epithelium is characteristic of early chronic rejection following liver transplantation. Recent studies have suggested that intrahepatic biliary epithelial cells can transform into myofibroblasts. This study examines the induction and molecular regulation of this transition during allograft rejection. Immortalized human cholangiocytes were stimulated with either transforming growth factor b1 (TGFb1) or a T cell line, and they were examined for morphological, proteomic, and functional features. Posttransplant liver biopsy sections were also examined. Treatment of cholangiocytes with TGFb1 or TGFbpresenting T cells induced a bipolar morphology, reduced expression of E-cadherin and zona occludens 1 (ZO-1), and increased vimentin, fibronectin, matrix metalloproteinase 2 (MMP-2), MMP-9, and S100 calcium binding protein A4 (S100A4); treated cells invaded a model basement membrane. Chemokines induced T cell penetration of 3-dimensional, cultured bile duct-like structures and bile ducts in liver biopsy sections. A spatial association was observed between ductinfiltrating T cells and cholangiocyte expression of mesenchymal markers, including S100A4. Inhibition of S100A4 expression in vitro blocked TGFb1-mediated loss of E-cadherin and ZO-1 but did not reduce induction of fibronectin, MMP-2, or MMP-9. This study demonstrates the potential for T cells to induce an intrahepatic biliary epithelial-to-mesenchymal cell transition during chronic rejection. Furthermore, S100A4 expression by cholangiocytes was identified as a crucial regulator of this transition.