Pathology of cholestasis-induced intrahepatic epithelial-mesenchymal transition

Objective To study the characteristics of cholestasis-induced epithelial-mesenchymal transition（EMT） in biliary duct of rats with biliary fibrosis. Methods A rat biliary fibrosis model was induced by bile duct ligation（BDL）.Expression of markers in cholestasis-induced EMT of rats with biliary fibrosis was detected with H＆E,immunohistochemistry and immunofluorescence staining. Results The cholangiocytes in hepatic portal area,fibroblasts around biliary duct,and fiber matrix were significantly increased in rats due to cholestasis after BDL.Immunohistochemistry showed that the epithelial marker,cytokeratin 19（CK19）,was expressed in hepatic cholangiocytes of sham-operation group and BDL group.However,the mesenchymal cell markers,vimentin and FSP1/S100A4,were only expressed in hepatic cholangiocytes of BDL group.The mesenchymal cell marker,vimentin,in new bile canaliculi of portal area was strongly positive in rats 1 week after BDL and positive in many cells around the proliferated bile duct in rats 2 weeks after BDL.The myofibroblast marker,α-SMA,was not expressed in sham-operation group and BDL group,and the α-SMA positive cells were mainly distributed around the cholangiocytes in portal area. Conclusion Proliferation and EMT of intrahepatic cholangiocytes occur during cholestasis-induced biliary fibrosis in rats,thus contributing to hepatic fibrosis.