OBJECTIVETo investigate the occurrence of epithelial to mesenchymal phenotype transition (EMT) in the liver of rats following bile duct ligation (BDL).

METHODSTwenty-four male Wistar rats were randomized into sham-operated group and BDL group. Liver fibrosis of the rats was evaluated by HE staining and Masson's trichrome staining. Western blotting was used to detect the expression levels of the epithelial markers albumin and E-cadherin and the mesenchymal markers type I collagen and vimentin in the liver tissue. Immunofluorescence was employed to determine the co-localizations of FSP-1+vimentin, FSP-1+type I collagen, FSP-1+albumin, and albumin+type I collagen in cells.

RESULTSCompared with those in sham-operated group, the rats in BDL group showed significantly increased ISHAK fibrosis score (4.42+1.16 vs 0, P+0.000), METAVIR fibrosis score (3.42+0.67 vs 0, P+0.000) and type I collagen levels (0.30+0.06 vs 0.11+0.07, P+0.000) with up-regulated protein levels of albumin (0.53+0.63 vs 1.12+0.01, P+0.000) and E-cadherin (0.21+0.01 vs 0.44+0.01, P+0.000) and down-regulated type I collagen (8.21+0.12 vs 0.24+0.01, P+0.000) and vimentin (3.14+0.01 vs 0.37+0.01, P+0.000). The number of cells with co-localizations of FSP-1+vimentin, FSP-1+type I collagen, FSP-1+albumin, and albumin+type I collagen was also significantly increased in BDL group.

CONCLUSIONBDL causes significantly decreased expression of epithelial markers and increased expressions of the mesenchymal markers in rats, indicating the occurrence of EMT in some of the liver cells.