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Morell CM, Fiorotto R, Meroni M, Raizner A, Torsello B, Cadamuro M, Spagnuolo G, Kaffe E, Sutti S, Albano E, Strazzabosco M. Notch signaling and progenitor/ductular reaction in steatohepatitis. PLoS One 2017; 12:e0187384. [PMID: 29140985 PMCID: PMC5687773 DOI: 10.1371/journal.pone.0187384] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 10/18/2017] [Indexed: 12/11/2022] Open
Abstract
Background and objective Persistent hepatic progenitor cells (HPC) activation resulting in ductular reaction (DR) is responsible for pathologic liver repair in cholangiopathies. Also, HPC/DR expansion correlates with fibrosis in several chronic liver diseases, including steatohepatitis. Increasing evidence indicates Notch signaling as a key regulator of HPC/DR response in biliary and more in general liver injuries. Therefore, we aimed to investigate the role of Notch during HPC/DR activation in a mouse model of steatohepatitis. Methods Steatohepatitis was generated using methionine-choline deficient (MCD) diet. For hepatocyte lineage tracing, R26R-YFP mice were infected with AAV8-TBG-Cre. Results MCD diet promoted a strong HPC/DR response that progressively diffused in the lobule, and correlated with increased fibrosis and TGF-β1 expression. Notch signaling was unchanged in laser-capture microdissected HPC/DR, whereas Notch receptors were down regulated in hepatocytes. However, in-vivo lineage tracing experiments identified discrete hepatocytes showing Notch-1 activation and expressing (the Notch-dependent) Sox9. Stimulation of AML-12 hepatocyte-cell line with immobilized Jag1 induced Sox9 and down-regulated albumin and BSEP expression. TGF-β1 treatment in primary hepatic stellate cells (HSC) induced Jag1 expression. In MCD diet-fed mice, αSMA-positive HSC were localized around Sox9 expressing hepatocytes, suggesting that Notch activation in hepatocytes was promoted by TGF-β1 stimulated HSC. In-vivo Notch inhibition reduced HPC response and fibrosis progression. Conclusion Our data suggest that Notch signaling is an important regulator of DR and that in steatohepatitis, hepatocytes exposed to Jag1-positive HSC, contribute to pathologic DR by undergoing Notch-mediated differentiation towards an HPC-like phenotype. Given the roles of Notch in fibrosis and liver cancer, these data suggest mesenchymal expression of Jag1 as an alternative therapeutic target.
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Affiliation(s)
- Carola M. Morell
- International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Romina Fiorotto
- International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
- Liver Center, Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut, United States of America
| | - Marica Meroni
- International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Aileen Raizner
- Liver Center, Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut, United States of America
| | - Barbara Torsello
- International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Massimiliano Cadamuro
- International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Gaia Spagnuolo
- International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Eleanna Kaffe
- Liver Center, Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut, United States of America
| | - Salvatore Sutti
- Department of Health Sciences, University “A. Avogadro” of East Piedmont, Novara, Italy
| | - Emanuele Albano
- Department of Health Sciences, University “A. Avogadro” of East Piedmont, Novara, Italy
| | - Mario Strazzabosco
- International Center for Digestive Health, Department of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
- Liver Center, Department of Internal Medicine, Section of Digestive Diseases, Yale University, New Haven, Connecticut, United States of America
- * E-mail:
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