OBJECTIVETo investigate the mechanism of hepatocytes transdifferentiation to bile duct epithelial cells (BECs) and intervention of Huangqi decoction (HQD) on hepatic fibrosis formation in rats with secondary cholestasis.

METHODSSeventy-five SD male rats were made into cholestatic hepatic fibrosis model animals by bile duct ligation, and randomized into the control group (n = 50) and the HQD group (n = 15). Starting from one week after modeling, they were administered orally with saline and HQD respectively for four weeks. Besides, a sham-operated group was set up with 10 rats operated by choledochus segregating only and administered after then with saline. Rats were killed in batches at different time points, i.e. each five from the control group and sham-operated group at the end of the 1st week, five from the control group for each time at the end of the 2nd, 3rd and 4th week, and all the remaining rats at the end of the 5th week. Their liver tissues were taken for histological change examination, content of hydroxyproline (Hyp) determination; protein expression of BECs marker cytokeratin 7 (CK7) and the hepatocyte specific antigen HepPar detection by Western blot, and CK7-Hep Par co-localization by laser confocal microscopy. Then IPP software was used to analyze Sirius red stained positive areas of CK7 and Hep Par, as well as the average IOD of CK7/Hep Par co-localization.

RESULTSHepatocytes in hepatic tissues (Hep Par positive cell) in the model rats decreased gradually along was time went by after modeling (Sham > M1w > M2w > M3w > M4w > M5w), which was in parallel with the increase of BECs (CK7 positive cells), degree of fibrosis, Hyp content and CK7 protein expression. Increasing of co-localized positive cells of CK7/Hep Par began at 1 week and reached the peak 3 weeks after modeling, then it decreased gradually. The Hep Par protein expression was negatively correlated with that of CK7; the Hep Par positive cell expression was negatively correlated with CK7 positive cell expression and collagen deposition; while the CK7 positive cell expression was positively correlated with the collagen deposition in the liver tissue. Compared with the model control group, the mortality, CK7/Hep Par co-localized positive cells, fibrosis degree, Hyp content and CK7 protein expression were lesser obviously (P < 0.01), while Hep Par positive cell and protein expressions were higher significantly in the HQD group.

CONCLUSIONSHepatocytes transdifferentiation to BECs might be a key pathological element for secondary cholestatic hepatic fibrosis formation; the restraining action of HQD is possibly a major action mechanism of HQD for effectively intervening and treating secondary cholestasis hepatic fibrosis.