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Machado MV, Michelotti GA, Pereira TA, Xie G, Premont R, Cortez-Pinto H, Diehl AM. Accumulation of duct cells with activated YAP parallels fibrosis progression in non-alcoholic fatty liver disease. J Hepatol 2015; 63:962-70. [PMID: 26070409 PMCID: PMC4575842 DOI: 10.1016/j.jhep.2015.05.031] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/21/2015] [Accepted: 05/22/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Mechanisms that regulate regeneration of injured livers are complex. YAP, a stem cell associated factor, controls liver growth in healthy adult mice. Increasing nuclear localization of YAP triggers accumulation of reactive-appearing ductular cells (YAP+RDC) with liver progenitor capabilities. The significance of YAP activation, and mechanisms involved, are unknown in diseased livers. We evaluated the hypothesis that YAP is more activated in injured livers that are scarring than in those that are regenerating effectively. METHODS Immunohistochemistry and qRT-PCR analysis were used to localize and quantify changes in YAP and RDC in 52 patients with non-alcoholic fatty liver disease (NAFLD) and two mouse models of diet-induced non-alcoholic steatohepatitis (NASH). Results were correlated with liver disease severity, metabolic risk factors, and factors proven to control NAFLD progression. RESULTS YAP increased in NAFLD where it mainly localized in nuclei of RDC that expressed progenitor markers. Accumulation of YAP+RDC paralleled the severity of hepatocyte injury and accumulation of Sonic hedgehog, but not steatosis or metabolic risk factors. YAP+RDC expressed osteopontin, a Shh-regulated fibrogenic factor. Myofibroblast accumulation, fibrosis, and numbers of YAP+RDC strongly correlated. In murine NASH models, atrophic fibrotic livers contained significantly more YAP+RDC than livers with less severe NASH. CONCLUSION YAP+RDC promote scarring, rather than effective regeneration, during NASH.
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Affiliation(s)
- Mariana Verdelho Machado
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA; Gastroenterology Department, Hospital de Santa Maria, CHLN, Lisbon, Portugal
| | | | - Thiago Almeida Pereira
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Guanhua Xie
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Richard Premont
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
| | - Helena Cortez-Pinto
- Gastroenterology Department, Hospital de Santa Maria, CHLN, Lisbon, Portugal
| | - Anna Mae Diehl
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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Michelotti GA, Xie G, Swiderska M, Choi SS, Karaca G, Krüger L, Premont R, Yang L, Syn WK, Metzger D, Diehl AM. Smoothened is a master regulator of adult liver repair. J Clin Invest 2013; 123:2380-94. [PMID: 23563311 DOI: 10.1172/jci66904] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 02/12/2013] [Indexed: 12/16/2022] Open
Abstract
When regenerative processes cannot keep pace with cell death, functional epithelia are replaced by scar. Scarring is characterized by both excessive accumulation of fibrous matrix and persistent outgrowth of cell types that accumulate transiently during successful wound healing, including myofibroblasts (MFs) and progenitors. This suggests that signaling that normally directs these cells to repair injured epithelia is deregulated. To evaluate this possibility, we examined liver repair during different types of liver injury after Smoothened (SMO), an obligate intermediate in the Hedgehog (Hh) signaling pathway, was conditionally deleted in cells expressing the MF-associated gene, αSMA. Surprisingly, blocking canonical Hh signaling in MFs not only inhibited liver fibrosis but also prevented accumulation of liver progenitors. Hh-sensitive, hepatic stellate cells (HSCs) were identified as the source of both MFs and progenitors by lineage-tracing studies in 3 other strains of mice, coupled with analysis of highly pure HSC preparations using flow cytometry, immunofluorescence confocal microscopy, RT-PCR, and in situ hybridization. The results identify SMO as a master regulator of hepatic epithelial regeneration based on its ability to promote mesenchymal-to-epithelial transitions in a subpopulation of HSC-derived MFs with features of multipotent progenitors.
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Affiliation(s)
- Gregory A Michelotti
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
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Chen Y, Choi SS, Michelotti GA, Chan IS, Swiderska M, Karaca GF, Xie G, Moylan CA, Garibaldi F, Premont R, Suliman HB, Piantodosi CA, Diehl AM. Hedgehog controls hepatic stellate cell fate by regulating metabolism. Gastroenterology 2012; 143:1319-1329.e11. [PMID: 22885334 PMCID: PMC3480563 DOI: 10.1053/j.gastro.2012.07.115] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 07/24/2012] [Accepted: 07/29/2012] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS The pathogenesis of cirrhosis, a disabling outcome of defective liver repair, involves deregulated accumulation of myofibroblasts derived from quiescent hepatic stellate cells (HSCs), but the mechanisms that control transdifferentiation of HSCs are poorly understood. We investigated whether the Hedgehog (Hh) pathway controls the fate of HSCs by regulating metabolism. METHODS Microarray, quantitative polymerase chain reaction, and immunoblot analyses were used to identify metabolic genes that were differentially expressed in quiescent vs myofibroblast HSCs. Glycolysis and lactate production were disrupted in HSCs to determine if metabolism influenced transdifferentiation. Hh signaling and hypoxia-inducible factor 1α (HIF1α) activity were altered to identify factors that alter glycolytic activity. Changes in expression of genes that regulate glycolysis were quantified and localized in biopsy samples from patients with cirrhosis and liver samples from mice following administration of CCl(4) or bile duct ligation. Mice were given systemic inhibitors of Hh to determine if they affect glycolytic activity of the hepatic stroma; Hh signaling was also conditionally disrupted in myofibroblasts to determine the effects of glycolytic activity. RESULTS Transdifferentiation of cultured, quiescent HSCs into myofibroblasts induced glycolysis and caused lactate accumulation. Increased expression of genes that regulate glycolysis required Hh signaling and involved induction of HIF1α. Inhibitors of Hh signaling, HIF1α, glycolysis, or lactate accumulation converted myofibroblasts to quiescent HSCs. In diseased livers of animals and patients, numbers of glycolytic stromal cells were associated with the severity of fibrosis. Conditional disruption of Hh signaling in myofibroblasts reduced numbers of glycolytic myofibroblasts and liver fibrosis in mice; similar effects were observed following administration of pharmacologic inhibitors of Hh. CONCLUSIONS Hedgehog signaling controls the fate of HSCs by regulating metabolism. These findings might be applied to diagnosis and treatment of patients with cirrhosis.
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Affiliation(s)
- Yuping Chen
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Steve S. Choi
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA,Section of Gastroenterology, Department of Medicine, Durham Veterans Affairs Medical Center, Durham, North Carolina, USA
| | - Gregory A. Michelotti
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Isaac S. Chan
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Marzena Swiderska
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Gamze F. Karaca
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Guanhua Xie
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Cynthia A. Moylan
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA,Section of Gastroenterology, Department of Medicine, Durham Veterans Affairs Medical Center, Durham, North Carolina, USA
| | - Francesca Garibaldi
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Richard Premont
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Hagir B. Suliman
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | - Claude A. Piantodosi
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA,Department of Anesthesiology, Duke University, Durham, North Carolina, USA,Department of Pathology, Duke University, Durham, North Carolina, USA
| | - Anna Mae Diehl
- Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina.
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Abstract
OBJECTIVE The death rate of mature hepatocytes is chronically increased in various liver diseases, triggering responses that prevent liver atrophy, but often cause fibrosis. Mice with targeted disruption of inhibitor kappa B kinase (Ikk) in hepatocytes (HEP mice) provide a model to investigate this process because inhibiting Ikk-nuclear factor-kappaB (NF-kappaB) signalling in hepatocytes increases their apoptosis. METHODS Cell proliferation, apoptosis, progenitors, fibrosis and production of Hedgehog (Hh) ligands (progenitor and myofibroblast growth factors) were compared in HEP and control mice before and after feeding methionine choline-deficient ethionine-supplemented (MCDE) diets. Ikkbeta was deleted from primary hepatocytes to determine the effects on Hh ligand production; Hh signalling was inhibited directly in progenitors to determine the effects on viability. Liver sections from patients were examined to assess relationships between hepatocyte production of Hh ligands, accumulation of myofibroblastic cells and liver fibrosis. RESULTS Disrupting the Ikk-NF-kappaB pathway in hepatocytes inhibited their proliferation but induced their production of Hh ligands. The latter provided viability signals for progenitors and myofibroblasts, enhancing accumulation of these cell types and causing fibrogenesis. Findings in the mouse models were recapitulated in diseased human livers. CONCLUSION Dying mature hepatocytes produce Hh ligands which promote the compensatory outgrowth of progenitors and myofibroblasts. These results help to explain why diseases that chronically increase hepatocyte death promote cirrhosis.
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Affiliation(s)
- Youngmi Jung
- Department of Medicine, Duke University, Durham, North Carolina
| | - Rafal P. Witek
- Department of Medicine, Duke University, Durham, North Carolina
| | - Wing-Kin Syn
- Department of Medicine, Duke University, Durham, North Carolina
| | - Steve S. Choi
- Department of Medicine, Duke University, Durham, North Carolina
| | | | - Richard Premont
- Department of Medicine, Duke University, Durham, North Carolina
| | - Cynthia D. Guy
- Department of Pathology, Duke University, Durham, North Carolina
| | - Anna Mae Diehl
- Department of Medicine, Duke University, Durham, North Carolina
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