β-Adrenoceptor blockade in sclerosing cholangitis of Mdr2 knockout mice: antifibrotic effects in a model of nonsinusoidal fibrosis

Primary sclerosing cholangitis (PSC) is a cholestatic liver disease with high propensity to develop into cholangiocarcinoma. The hepatobiliary disorder of PSC is due to progressive fibrosis surrounding the intra- and extrahepatic bile ducts. Until now, no effective medical therapy exists. To study the progression of sclerosing cholangitis after inhibition of the sympathetic nervous system by blockade of the β-adrenoceptors, we used the Mdr2(-/-) mouse model, which develops periportal fibrosis similar to human PSC. Liver tissues of Mdr2(-/-) mice untreated or treated with the β-adrenoceptor antagonist propranolol were analyzed for inflammation and fibrosis progression at different time points by histological scoring and immunostaining for α-smooth muscle actin (α-SMA), CD45 and S100A4. Transaminases and hydroxyproline contents were determined. Expression of angiotensinogen, endothelin-1, TGF-β, TNF-α, CTGF and procollagen 1A1 was studied by real-time PCR on laser-microdissected areas of acinar zones I and II-III. After 3 months, periportal fibrosis had developed in Mdr2(-/-) mice, but immunostaining revealed no sinusoidal and only minor periportal contribution of myofibroblasts with prominent fibroblasts. Propranolol treatment of Mdr2(-/-) mice improved liver architecture. Additionally, inflammation and fibrosis were significantly reduced. After 3 months of treatment, the antifibrotic effect of the β-blockade was most obvious. The transcript levels of procollagen 1A1, TNF-α, TGF-β, CTGF and endothelin-1 were markedly repressed in the portal areas of treated mice. Taken together, these data show that propranolol efficiently delays progression of sclerosing cholangitis. Therefore, the blockade of β-adrenoceptors is a promising option to support future therapeutic strategies in the treatment of human PSC.

[Epithelial-mesenchymal transition of biliary epithelial cells in advanced liver fibrosis]

The conversion of epithelial cells in a mesenchymal cell type is called "epithelial-mesenchymal-transition" (EMT). This process is defined by a loss of epithelial specific characteristics such as cell adhesion, polarity and a reorganization of cytoskeletal proteins. EMT has been shown to be involved in progression of cancer and in obstructive renal fibrosis. In this study we analyzed liver tissues in a bile-duct ligation model of rats and human liver biopsies with cholestatic fibrosis and chronic hepatitis c infection to determine if biliary epithelial cells undergo phenotypical and functional changes during chronic injury.

METHODS

Liver tissue of rats and human patients was examined by immunohistochemistry using antibodies against epithelial and mesenchymal specific targets as well as molecules of potentially activated signaling pathways. To study contribution of biliary epithelial cells in extracellular matrix production we performed laser microdissection combined with real-time PCR.

RESULTS

Bile duct ligation in rats induced a prominent biliary epithelial proliferation and a pronounced expression of vimentin was observed in biliary epithelial cells, whereas no vimentin expression was detectable in bile duct cells of sham operated rats. In human liver biopsies from patients with cholestatic fibrosis and chronic hepatitis c infection a prominent biliary expression of vimentin could be shown. Despite this, epithelial marker proteins were still detectable. Further, we observed collagen I mRNA expression in laser microdissected bile ducts.

CONCLUSION

Biliary epithelial cells show cytoskeletal rearrangements during chronic liver injury towards a mesenchymal phenotype. The detection of collagen I mRNA in bile duct cells suggests that they might participate in extracellular matrix production.

Monitoring of piglets' open field activity and choice behaviour during the replay of maternal vocalization: a comparison between Observer and PID technique

The paper presents a new system for the automatic monitoring of open field activity and choice behaviour of medium-sized animals. Passive infrared motion detectors (PID) were linked on-line via a digital I/O interface to a personal computer provided with self-developed analysis software based on LabVIEW (PID technique). The set up was used for testing 18 one-week-old piglets (Sus scrofa) for their approach to their mother's nursing vocalization replayed through loudspeakers. The results were validated by comparison with a conventional Observer technique, a computer-aided direct observation. In most of the cases, no differences were seen between the Observer and PID technique regarding the percentage of stay in previously defined open field segments, the locomotor open field activity, and the choice behaviour. The results revealed that piglets are clearly attracted by their mother's nursing vocalization. The monitoring system presented in this study is thus suitable for detailed behavioural investigations of individual acoustic recognition. In general, the PID technique is a useful tool for research into the behaviour of individual animals in a restricted open field which does not rely on subjective analysis by a human observer.