A. L. Sobbe

Rapamycin inhibits hepatic fibrosis in rats by attenuating multiple profibrogenic pathways

Hepatic stellate cell transdifferentiation, epithelial‐mesenchymal cell transition, and the ductular reaction each contribute to the development of hepatic fibrosis in cholestatic liver diseases. Inhibitors of mammalian target of rapamycin have antifibrotic properties. We evaluated the hypothesis that the antifibrotic action of rapamycin is due to attenuated myofibroblast proliferation in addition to an inhibitory effect on epithelial‐mesenchymal transition and the ductular reaction. Hepatic fibrosis was induced by bile duct ligation, and rodents received 1.5 mg/kg/day rapamycin by subcutaneous infusion for 21 days. The expression of various markers of hepatic fibrosis, stellate cell transactivation, epithelial‐mesenchymal transition, and the ductular reaction was compared between treated and untreated animals. Hepatic fibrosis, hepatic procollagen type 1 messenger RNA, and alpha‐smooth muscle actin expression were significantly reduced in treated animals. Hepatic stellate cell procollagen expression and proliferation were also reduced by rapamycin. The following markers of epithelial‐mesenchymal transition—vimentin protein expression, S100 calcium binding protein A4 and transforming growth factor beta 1 messenger RNA, and the mothers against decapentaplegic homolog signaling pathway—were all reduced after rapamycin treatment. The intensity of the ductular reaction was reduced by rapamycin as assessed by histopathological scoring and by reduced cytokeratin 19 expression. Rapamycin caused a reduction in hepatic progenitor cell proliferation. Together, these data show that multiple profibrogenic pathways are activated in an animal model of cholestasis and that rapamycin attenuates epithelial‐mesenchymal transition and the ductular reaction as well as hepatic stellate cell activation. Liver Transpl 15:1315–1324, 2009.

Lack of efficacy of mTOR inhibitors and ACE pathway inhibitors as antifibrotic agents in evolving and established fibrosis in Mdr2-/- mice

Mammalian target of rapamycin and angiotensin‐converting enzyme inhibition has been shown to have antifibrotic activity in models of liver fibrosis. The aim of our study was to determine the efficacy of rapamycin, everolimus, irbesartan and captopril, alone and in combination, as antifibrotic agents in the Mdr2−/− model of cholestasis both in early injury and established disease.

Inconsistent hepatic antifibrotic effects with the iron chelator deferasirox.

Development of effective antifibrotic treatments that can be translated to clinical practice is an important challenge in contemporary hepatology. A recent report on β‐thalassemia patients demonstrated that deferasirox treatment reversed or stabilized liver fibrosis independent of its iron‐chelating properties. In this study, we investigated deferasirox in cell and animal models to better understand its potential antifibrotic effects.

Isolated Hepatic Iron Deficiency Despite Abundant Systemic Iron in Mdr2-/- Mice: Integrity of the Biliary Transport System Is Important in Liver Iron Homeostasis

Introduction: The liver is central to the metabolism of both iron and cholesterol. Cholesterol is synthesised and further metabolised to bile acids in the liver and the liver plays an important role in regulation of iron metabolism. It is also the organ in which excess iron is stored. Clinically, links have been noted between lipid and iron metabolism, with approximately one - third of patients with non - alcoholic fatty liver disease exhibiting altered iron parameters. On a molecular level, we have previously reported that wild - type mice fed iron - deficient, normal or iron - loaded diets exhibited increased hepatic cholesterol and increased hepatic gene expression of enzymes in the cholesterol biosynthesis pathway with increasing hepatic iron burden. In the genetic disorder, haemochromatosis, the liver can become overloaded with iron; however, clinical studies have suggested that lipid metabolism may not be perturbed in haemochromatosis. Methods and Materials: We investigated hepatic cholesterol metabolis m in three mouse models of hereditary haemochromatosis: Hfe - / - , Tfr2 Y245X single mutant and Hfe - / - x Tfr2 Y245X double mutant animals as well as wild - type controls. Mice were fed normal mouse chow and sacrificed at 10 weeks of age. Hepatic gene expression, total cholesterol and non – haem iron were measured. Liver non - haem iron was similar in Hfe - / - and Tfr2 Y245X mice (16.6±0.8 and 17±1 μmol Fe /g liver, respectively) and significantly higher in the double mutant animals (22.4±0.7 μmol Fe /g liver ; P<0.004) than either of the single mutant mice. Results: Only one group of genes increased significantly with increasing hepatic iron: those involved in cholesterol transport. Gene expression of apolipoproteins A4, C1, C2, C3 and E increased significantly with increasing hepatic iron as did expression of VLDL receptor. In contrast to our findings in wild - type mice, gene expression of cholesterol biosynthetic enzymes did not increase significantly with liver iron burden and there were no differences in hepatic cholesterol between the groups of mutant mice. We also measured expression of genes involved in cholesterol regulation, which similarly, did not increase with increasing hepatic iron. Approximately 50% of cholesterol synthesised in the liver is directed to bile acid synthesis; however, gene expression of bile acid pathway enzymes did not change with respect to hepatic iron burden. Conclusion: These results suggest that iron - associated cholesterol regulation may be ameliorated by the genetic changes which occur in haemochromatosis.Poster presented at Fifth Congress of the International BioIron Society that took place in University College London (London, United Kingdom) during 14-18th April 2013.

Altered expression of iron-regualtory genes in an animal model of cholestasis

Matrix metalloproteinases and their inhibitors are altered in a time-course model of irinotecaninduced mucositis N AL-DASOOQI, R GIBSON, J BOWEN, R LOGAN, A STRINGER, D KEEFE Department of Medicine, University of Adelaide, Department of Medical Oncology, Royal Adelaide Hospital, School of Medical Sciences, University of Adelaide, Division of Surgical Pathology, SA Pathology, Oral Pathology, School of Dentistry, Faculty of Health Sciences, University of Adelaide, Cancer Council South Australia, Eastwood, Australia