Background and aim: Epithelial-mesenchymal transition (EMT) of biliary epithelial cells (BECs) plays major roles in many cholangiopathies. This study evaluated whether EMT of BECs has a role in hepatolithiasis-induced biliary fibrosis and types of BECs that are involved.
Methods: The expression of EMT-related proteins and epidermal growth factor receptor was evaluated by immunohistochemistry of liver tissues from 102 patients with hepatolithiasis, 32 patients with post-hepatitis cirrhosis, and 48 normal livers. Antibodies against E-cadherin, β-catenin, and cytokeratin were used to identify epithelial cells and antibodies against vimentin, S100A4, podoplanin, and α-smooth muscle actin (α-SMA) were used to identify mesenchymal cells. The relationship between clinical and histological parameters and immunohistochemistry findings in BECs, and the surrounding stroma were evaluated.
Results: Loss of E-cadherin and acquisition of S100A4 and vimentin were observed in BECs. In all BECs, cytokeratin and β-catenin expression were unchanged, while podoplanin and α-SMA were not expressed. Although hepatic fibrosis was more severe in post-hepatitis cirrhosis, EMT of BECs was more widespread in hepatolithiasis. In hepatolithiasis, EMT-related proteins were more highly expressed in small bile ducts than in medium or large bile ducts. Their expression was associated with the severity of biliary fibrosis and the expressions of epidermal growth factor receptor. Expression of α-SMA in fibroblasts from the portal space was closely linked to pathological changes in small bile ducts and EMT-related protein expressions in BECs.
Conclusions: Proliferating cholangiocytes that form small bile ducts may contribute to cholangiopathies in hepatolithiasis through an EMT-like phenomenon or through interactions with stromal myofibroblasts.
Keywords: EGFR; biliary epithelial cell; epithelial-mesenchymal transition; hepatolithiasis.
© 2013 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.