Published online Jun 21, 2017. doi: 10.3748/wjg.v23.i23.4191
Peer-review started: December 28, 2016
First decision: February 10, 2017
Revised: February 27, 2017
Accepted: May 9, 2017
Article in press: May 9, 2017
Published online: June 21, 2017
To analyze time intervals of inflammation and regeneration in a cholestatic rat liver model.
In 36 Lewis rats, divided into six groups of 6 animals (postoperative observation periods: 1, 2, 3, 4, 6, 8 wk), the main bile duct was ligated with two ligatures and observed for the periods mentioned above. For laboratory evaluation, cholestasis parameters (bilirubin, γ-GT), liver cell parameters (ASAT, ALAT) and liver synthesis parameters (quick, albumin) were determined. For histological analysis, HE, EvG, ASDCL and HMGB-1 stainings were performed. Furthermore, we used the mRNA of IL-33, GADD45a and p-21 for analyzing cellular stress and regeneration in cholestatic rats.
In chemical laboratory and histological evaluation, a distinction between acute and chronic cholestatic liver injury with identification of inflammation and regeneration could be demonstrated by an increase in cholestasis (bilirubin: 1-wk group, 156.83 ± 34.12 μmol/L, P = 0.004) and liver cell parameters (ASAT: 2-wk group, 2.1 ± 2.19 μmol/L.s, P = 0.03; ALAT: 2-wk group, 1.03 ± 0.38 μmol/L.s, P = 0.03) after bile duct ligation (BDL). Histological evaluation showed an increase of bile ducts per portal field (3-wk group, 48 ± 6.13, P = 0.004) during the first four weeks after bile duct ligation. In addition to inflammation, which is an expression of acute cholestasis, there was an increase of necrotic areas in the histological sections (2-wk group, 1.38% ± 2.28% per slide, P = 0.002). Furthermore, the inflammation could be verified by ASDCL (4-wk group, 22 ± 5.93 positive cells per portal field, P = 0.041) and HMGB-1 [2-wk group, 13 ± 8.18 positive cells per field of view (FoV), P = 0.065] staining. Therefore, in summary of the laboratory evaluation and histological studies, acute cholestasis could be found during the first four weeks after bile duct ligation. Subsequently, the described parameters declined so that chronic cholestasis could be assumed. For quantification of secondary biliary cirrhosis, eosin staining was performed, which did not reveal any signs of liver remodeling, thus precluding the development of a chronic cholestasis model. Additionally, to establish the chronic cholestasis model, we evaluated liver regeneration capacity through measurements of IL-33, p-21 and GADD45a mRNA.
We created a chronic cholestasis model. The point of inflammatory and regenerative balance was reached after four weeks. This finding should be used for experimental approaches dealing with chronic cholestatic liver damage.
Core tip: Animal research models mostly address either acute cholestasis or secondary biliary cirrhosis, neither of which reflect the clinical reality of central liver tumors with cholestatic liver damage without secondary liver cirrhosis. In this work, we present our data from a model simulating chronic cholestatic liver damage in an otherwise healthy liver.