The biliary epithelium gives rise to liver progenitor cells.

UNLABELLED: Severe liver diseases are characterized by expansion of liver progenitor cells (LPC), which correlates with disease severity. However, the origin and role of LPC in liver physiology and in hepatic injury remains a contentious topic. We found that ductular reaction cells in human cirrhotic livers express hepatocyte nuclear factor 1 homeobox B (HNF1ß). However, HNF1ß expression was not present in newly generated epithelial cell adhesion molecule (EpCAM)-positive hepatocytes. In order to investigate the role of HNF1ß-expressing cells we used a tamoxifen-inducible Hnf1ßCreER/R26R(Yfp/LacZ) mouse to lineage-trace Hnf1ß(+) biliary duct cells and to assess their contribution to LPC expansion and hepatocyte generation. Lineage tracing demonstrated no contribution of HNF1ß(+) cells to hepatocytes during liver homeostasis in healthy mice or after loss of liver mass. After acute acetaminophen or carbon tetrachloride injury no contribution of HNF1ß(+) cells to hepatocyte was detected. We next assessed the contribution of Hnf1ß(+) -derived cells following two liver injury models with LPC expansion, a diethoxycarbonyl-1,4-dihydro-collidin (DDC)-diet and a choline-deficient ethionine-supplemented (CDE)-diet. The contribution of Hnf1ß(+) cells to liver regeneration was dependent on the liver injury model. While no contribution was observed after DDC-diet treatment, mice fed with a CDE-diet showed a small population of hepatocytes derived from Hnf1ß(+) cells that were expanded to 1.86% of total hepatocytes after injury recovery. Genome-wide expression profile of Hnf1ß(+) -derived cells from the DDC and CDE models indicated that no contribution of LPC to hepatocytes was associated with LPC expression of genes related to telomere maintenance, inflammation, and chemokine signaling pathways. CONCLUSION: HNF1ß(+) biliary duct cells are the origin of LPC. HNF1ß(+) cells do not contribute to hepatocyte turnover in the healthy liver, but after certain liver injury, they can differentiate to hepatocytes contributing to liver regeneration.

The biological response modifier AM3 attenuates the inflammatory cell response and hepatic fibrosis in rats with biliary cirrhosis.

BACKGROUND: An inflammatory immune system response ensues in the liver and in the systemic circulation in cirrhosis, where it contributes to hepatic fibrosis and peripheral vasodilation. Modulation of the inflammatory response without increasing susceptibility to infection is a therapeutic target in cirrhosis. AM3 is a low-toxicity biological response modifier with regulatory effects on innate and adaptative immunity, and the ability to normalise the production of tumour necrosis factor alpha (TNFalpha). AIMS: This was an experimental study to investigate the effects of oral AM3 on the systemic and hepatic inflammatory response, liver fibrosis and on the haemodynamic abnormalities of portal hypertension in rats with biliary cirrhosis. DESIGN: Bile-duct ligated rats received a 3-week oral course of AM3 or placebo. RESULTS: In cirrhotic rats, AM3 blunted the inflammatory switch of circulating and intrahepatic monocytes and T-cells to TNFalpha and interferon gamma (IFNgamma) production, respectively. AM3 modified the intrahepatic polarisation pattern of the regulatory cytokines, decreasing the mRNA expression of transforming growth factor beta1 (TGFbeta1), interleukin 4 (IL4), and IFNgamma, and increasing that of IL10. Total and IFNgamma-producing natural killer (NK) cells were lowered by AM3 in the peripheral blood and liver of cirrhotic rats. The immunomodulatory effects of AM3 led to reduced hepatic fibrogenesis in cirrhotic rats, as shown by decreased area of liver fibrosis, hydroxyproline content and mRNA expression of procollagen alpha1(I). Besides, AM3 lowered portal pressure and systemic hyperaemia. CONCLUSIONS: The biological response modifier AM3 reverses the concurrent inflammatory immune system activation in peripheral blood and liver of experimental established cirrhosis, which results in reductions of hepatic fibrosis, portal pressure and peripheral vasodilation.

[Treatment of liver fibrosis]. / Tratamiento de la fibrosis hepática.

Liver fibrosis is the progressive deposition of extracellular matrix in the liver parenchyma that precedes the development of cirrhosis. In the last few years, knowledge of the cellular and molecular bases of liver fibrosis has increased considerably. Environmental and genetic factors have been described that influence the progression of liver fibrosis, while non-invasive methods have been developed that allow the grade of fibrosis to be estimated without the need for liver biopsy. Currently, the only clearly effective treatment to attenuate or reverse liver fibrosis is elimination of the causative agent. When this is not feasible, fibrogenic factors (such as insulin resistance, obesity, alcohol intake, cannabis consumption, etc.) should be identified and treated. However, several agents are able to reduce liver fibrosis in experimental models of chronic liver damage. Few controlled clinical trials have been performed that evaluate the efficacy and safety of these agents and consequently the level of evidence supporting their use as anti-fibrogenic therapy is still low. The efficacy of the anti- fibrogenic drugs, renin-angiotensin system inhibitors, is currently being evaluated.

Tratamiento de la fibrosis hepática / Treatment of liver fibrosis

La fibrosis hepática (FH) es el depósito progresivo de matriz extracelular en el parénquima hepático que precede al desarrollo de cirrosis. El conocimiento de las bases celulares y moleculares de la FH ha aumentado considerablemente en las dos últimas décadas. Se han descrito factores ambientales y genéticos que influyen en su progresión, así como métodos no invasivos que permiten estimar el grado de fibrosis sin necesidad de realizar una biopsia hepática. En la actualidad, el único tratamiento claramente efectivo para atenuar o revertir la FH es la eliminación del agente causal. En los casos en los que esto no es posible, se recomienda identificar y tratar factores profibrogénicos (como la resistencia a la insulina, la obesidad, el consumo de alcohol, el consumo de cannabis, etc.). Se han descrito diversos agentes capaces de reducir la FH en modelos experimentales de daño hepático crónico. No obstante, apenas existen estudios clínicos controlados que evaluen la eficacia y la seguridad de estos agentes, por lo que no existe suficiente evidencia científica para indicarlos como tratamiento antifibrogénicos. La eficacia de los inhibidores del sistema renina-angiotensina como fármacos antifibrogénicos se está evaluando en la actualidad(AU)

Liver fibrosis is the progressive deposition of extracellular matrix in the liver parenchyma that precedes the development of cirrhosis. In the last few years, knowledge of the cellular and molecular bases of liver fibrosis has increased considerably. Environmental and genetic factors have been described that influence the progression of liver fibrosis, while non-invasive methods have been developed that allow the grade of fibrosis to be estimated without the need for liver biopsy. Currently, the only clearly effective treatment to attenuate or reverse liver fibrosis is elimination of the causative agent. When this is not feasible, fibrogenic factors (such as insulin resistance, obesity, alcohol intake, cannabis consumption, etc.) should be identified and treated. However, several agents are able to reduce liver fibrosis in experimental models of chronic liver damage. Few controlled clinical trials have been performed that evaluate the efficacy and safety of these agents and consequently the level of evidence supporting their use as anti-fibrogenic therapy is still low. The efficacy of the anti- fibrogenic drugs, renin-angiotensin system inhibitors, is currently being evaluated(AU)