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Sanfeliu-Redondo D, Gibert-Ramos A, Gracia-Sancho J. Cell senescence in liver diseases: pathological mechanism and theranostic opportunity. Nat Rev Gastroenterol Hepatol 2024; 21:477-492. [PMID: 38485755 DOI: 10.1038/s41575-024-00913-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/12/2024] [Indexed: 06/30/2024]
Abstract
The liver is not oblivious to the passage of time, as ageing is a major risk factor for the development of acute and chronic liver diseases. Ageing produces alterations in all hepatic cells, affecting their phenotype and function and worsening the prognosis of liver disease. The ageing process also implies the accumulation of a cellular state characterized by a persistent proliferation arrest and a specific secretory phenotype named cellular senescence. Indeed, senescent cells have key roles in many physiological processes; however, their accumulation owing to ageing or pathological conditions contributes to the damage occurring in chronic diseases. The aim of this Review is to provide an updated description of the pathophysiological events in which hepatic senescent cells are involved and their role in liver disease progression. Finally, we discuss novel geroscience therapies that could be applied to prevent or improve liver diseases and age-mediated hepatic deregulations.
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Affiliation(s)
- David Sanfeliu-Redondo
- Liver Vascular Biology Laboratory, IDIBAPS Biomedical Research Institute - Hospital Clínic de Barcelona & CIBEREHD, Barcelona, Spain
| | - Albert Gibert-Ramos
- Liver Vascular Biology Laboratory, IDIBAPS Biomedical Research Institute - Hospital Clínic de Barcelona & CIBEREHD, Barcelona, Spain
| | - Jordi Gracia-Sancho
- Liver Vascular Biology Laboratory, IDIBAPS Biomedical Research Institute - Hospital Clínic de Barcelona & CIBEREHD, Barcelona, Spain.
- Department of Visceral Surgery and Medicine, Inselspital - University of Bern, Bern, Switzerland.
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2
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Zhang M, Serna-Salas S, Damba T, Borghesan M, Demaria M, Moshage H. Hepatic stellate cell senescence in liver fibrosis: Characteristics, mechanisms and perspectives. Mech Ageing Dev 2021; 199:111572. [PMID: 34536446 DOI: 10.1016/j.mad.2021.111572] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/15/2021] [Accepted: 09/10/2021] [Indexed: 02/08/2023]
Abstract
Myofibroblasts play an important role in fibrogenesis. Hepatic stellate cells are the main precursors of myofibroblasts. Cellular senescence is the terminal cell fate in which proliferating cells undergo irreversible cell cycle arrest. Senescent hepatic stellate cells were identified in liver fibrosis. Senescent hepatic stellate cells display decreased collagen production and proliferation. Therefore, induction of senescence could be a protective mechanism against progression of liver fibrosis and the concept of therapy-induced senescence has been proposed to treat liver fibrosis. In this review, characteristics of senescent hepatic stellate cells and the essential signaling pathways involved in senescence are reviewed. Furthermore, the potential impact of senescent hepatic stellate cells on other liver cell types are discussed. Senescent cells are cleared by the immune system. The persistence of senescent cells can remodel the microenvironment and interact with inflammatory cells to induce aging-related dysfunction. Therefore, senolytics, a class of compounds that selectively induce death of senescent cells, were introduced as treatment to remove senescent cells and consequently decrease the disadvantageous effects of persisting senescent cells. The effects of senescent hepatic stellate cells in liver fibrosis need further investigation.
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Affiliation(s)
- Mengfan Zhang
- Dept. of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Sandra Serna-Salas
- Dept. of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Turtushikh Damba
- Dept. of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands; School of Pharmacy, Mongolian National University of Medical Sciences, Ulaanbaatar, Mongolia
| | - Michaela Borghesan
- European Research Institute on the Biology of Aging (ERIBA), University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Marco Demaria
- European Research Institute on the Biology of Aging (ERIBA), University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Han Moshage
- Dept. of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
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Jiang T, Wang L, Li X, Song J, Wu X, Zhou S. Inositol-requiring enzyme 1-mediated endoplasmic reticulum stress triggers apoptosis and fibrosis formation in liver cirrhosis rat models. Mol Med Rep 2014; 11:2941-6. [PMID: 25434505 DOI: 10.3892/mmr.2014.3020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 09/12/2014] [Indexed: 01/12/2023] Open
Abstract
Long‑term and advanced cirrhosis is usually irreversible and often coincides with variceal hemorrhage or development of hepatocellular carcinoma; therefore, liver cirrhosis is a major cause of morbidity and mortality globally. The aim of the present study was to investigate the specific mechanism behind the formation of fibrosis or cirrhosis using rat models of hepatic fibrosis. The cirrhosis model was established by intraperitoneally administering dimethylnitrosamine to the rats. Hematoxylin and eosin staining was performed on the hepatic tissues of the rats to observe the fibrosis or cirrhosis, and western blot analysis was employed to detect α‑smooth muscle actin and desmin protein expression. Flow cytometric analysis was used to examine early and late apoptosis, and the protein and mRNA expression of endoplasmic reticulum (ER) stress-associated unfolded protein response (UPR) pathway proteins and apoptotic proteins [C/EBP homologous protein (CHOP) and caspase‑12] was detected by western blotting and the reverse-transcription polymerase chain reaction, respectively. The results indicated that the cirrhosis model was established successfully and that fibrosis was significantly increased in the cirrhosis model group compared with that in the normal control group. Flow cytometric analysis showed that early and late apoptosis in the cirrhosis model was significantly higher compared with that in the control group. The expression of the UPR pathway protein inositol-requiring enzyme (IRE) 1, as well as the expression of CHOP, was increased significantly in the cirrhotic rat tissues compared with that in the control group tissues (P<0.05). In conclusion, apoptosis was clearly observed in the hepatic tissue of cirrhotic rats, and the apoptosis was caused by activation of the ER stress-mediated IRE1 and CHOP.
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Affiliation(s)
- Tianpeng Jiang
- Department of Radiology, Affiliated Hospital of Guiyang Medical College, Guiyang, Guizhou 550004, P.R. China
| | - Lizhou Wang
- Department of Radiology, Affiliated Hospital of Guiyang Medical College, Guiyang, Guizhou 550004, P.R. China
| | - Xing Li
- Department of Radiology, Affiliated Hospital of Guiyang Medical College, Guiyang, Guizhou 550004, P.R. China
| | - Jie Song
- Department of Radiology, Affiliated Hospital of Guiyang Medical College, Guiyang, Guizhou 550004, P.R. China
| | - Xiaoping Wu
- Department of Radiology, Affiliated Hospital of Guiyang Medical College, Guiyang, Guizhou 550004, P.R. China
| | - Shi Zhou
- Department of Radiology, Affiliated Hospital of Guiyang Medical College, Guiyang, Guizhou 550004, P.R. China
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Takekoshi S, Kitatani K, Yamamoto Y. Roles of Oxidized Diacylglycerol for Carbon Tetrachloride-induced Liver Injury and Fibrosis in Mouse. Acta Histochem Cytochem 2014; 47:185-94. [PMID: 25861124 PMCID: PMC4387239 DOI: 10.1267/ahc.14030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 06/20/2014] [Indexed: 01/22/2023] Open
Abstract
Since there is a report that an inhibitor of protein kinase C (PKC) effectively suppresses the development of hepatic fibrosis, it is suggested that the PKC signaling pathway plays an important role in the pathogenesis of hepatic fibrosis. We reported that oxidized diacylglycerol (DAG), which is an activator of PKC, had a remarkably stronger PKC-activating action than un-oxidized DAG. In the present study, we explored the roles of oxidized DAG in hepatic fibrogenesis using mice, the livers of which developed fibrosis by long-term administration of carbon tetrachloride (CCl4). Liver fibrosis models were created by 4- or 8-week repetitive subcutaneous injections of CCl4 to the backs of C57BL/6J mice. The amount of oxidized DAG was significantly increased in the CCl4-treated group. Moreover, it was found that PKCα, βI, βII and δ were activated. In the CCl4-treated group, phosphorylation of ERK and JNK, which are downstream signal transmitters in the PKC pathway, was increased. It was also found in this group that there was an increase in TIMP-1, which is a fibrogenesis-promoting factor whose expression is enhanced by activated JNK, and of TNF-α, an inflammatory cytokine. Analysis by quantitative real-time RT-PCR showed that expressions of αSMA, collagen I, TNF-α and IL-10 were remarkably increased in the 8-week CCl4-treated group. The above results strongly suggested that oxidized DAG, which is increased by augmented oxidative stress, activated PKCα, βI, βII and δ molecular species and that these molecular species in turn stimulated the phosphorylation of MAP kinases including ERK and JNK, resulting in enhancement of hepatic fibrogenesis.
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Affiliation(s)
- Susumu Takekoshi
- Department of Cell Biology, Division of Host Defense Mechanism, Tokai University School of Medicine
| | - Kanae Kitatani
- Department of Cell Biology, Division of Host Defense Mechanism, Tokai University School of Medicine
| | - Yorihiro Yamamoto
- School of Bioscience and Biotechnology, Tokyo University of Technology
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Lee SJ, Kim KH, Park KK. Mechanisms of fibrogenesis in liver cirrhosis: The molecular aspects of epithelial-mesenchymal transition. World J Hepatol 2014; 6:207-216. [PMID: 24799989 PMCID: PMC4009476 DOI: 10.4254/wjh.v6.i4.207] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 01/09/2014] [Accepted: 03/04/2014] [Indexed: 02/06/2023] Open
Abstract
Liver injuries are repaired by fibrosis and regeneration. The cause of fibrosis and diminished regeneration, especially in liver cirrhosis, is still unknown. Epithelial-mesenchymal transition (EMT) has been found to be associated with liver fibrosis. The possibility that EMT could contribute to hepatic fibrogenesis reinforced the concept that activated hepatic stellate cells are not the only key players in the hepatic fibrogenic process and that other cell types, either hepatic or bone marrow-derived cells could contribute to this process. Following an initial enthusiasm for the discovery of this novel pathway in fibrogenesis, more recent research has started to cast serious doubts upon the real relevance of this phenomenon in human fibrogenetic disorders. The debate on the authenticity of EMT or on its contribution to the fibrogenic process has become very animated. The overall result is a general confusion on the meaning and on the definition of several key aspects. The aim of this article is to describe how EMT participates to hepatic fibrosis and discuss the evidence of supporting this possibility in order to reach reasonable and useful conclusions.
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Li R, Dai G, Zhao M, Zhang Y, Hui L, Zhang X, Jin B. Preventative effect of Astragalus flavescens on hepatic fibrosis in rats and its mechanism of action. Exp Ther Med 2013; 6:904-908. [PMID: 24137287 PMCID: PMC3797310 DOI: 10.3892/etm.2013.1232] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2013] [Accepted: 06/27/2013] [Indexed: 01/11/2023] Open
Abstract
The aim of this study was to investigate the preventative effect of Astragalus flavescens on hepatic fibrosis in rats and its mechanism of action. A total of 60 rats were randomly divided into normal control, model control, high-dose treatment and low-dose treatment groups, and a hepatic fibrosis model was established. The high- and low-dose treatment groups were treated with 2 g/100 g and 0.5 g/100 g Astragalus flavescens, respectively, once a day. Eight weeks following the initiation of treatment, the liver specimens of the rats were stained and observed under a light microscope. Hepatic fibrosis indices, specifically, type III precollagen (PC III), type IV collagen (C IV), hyaluronic acid (HA) and laminin (LN), were detected. Furthermore, the expression and localization of the hepatic fibrosis-related factors transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF) and platelet-derived growth factor-BB (PDGF-BB) were determined. The serum levels of hepatic fibrosis indices, and the liver tissue levels of hepatic fibrosis-related factors and collagen surface density in the model control group and the high- and low-dose treatment groups were significantly higher compared with those of the normal control group (P<0.05). In addition, the values in the two treatment groups were significantly lower compared with those of the model control group (P<0.05). The present study demonstrated that Astragalus flavescens effectively prevents hepatic fibrosis in rats. A possible mechanism for this is that it may reduce the expression levels of TGF-β1, PDGF-BB and CTGF, thereby inhibiting the activation of hepatic stellate cells and specifically blocking the signal transduction pathway of hepatic fibrosis.
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Affiliation(s)
- Rong Li
- Department of Gastroenterology, The First Hospital of Xi'an City, Xi'an, Shaanxi 710002; ; The Third Department of Internal Medicine, The Fifth Hospital of Xi'an City, Xi'an, Shaanxi 710082
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Abstract
Hepatic stellate cells (HSCs) are recognized as a major player in liver fibrogenesis. Upon liver injury, HSCs differentiate into myofibroblasts and participate in progression of fibrosis and cirrhosis. Additional cell types such as resident liver fibroblasts/myofibroblasts or bone marrow cells are also known to generate myofibroblasts. One of the major obstacles to understanding the mechanism of liver fibrogenesis is the lack of knowledge regarding the developmental origin of HSCs and other liver mesenchymal cells. Recent cell lineage analyses demonstrate that HSCs are derived from mesoderm during liver development. MesP1-expressing mesoderm gives rise to the septum transversum mesenchyme before liver formation and then to the liver mesothelium and mesenchymal cells, including HSCs and perivascular mesenchymal cells around the veins during liver development. During the growth of embryonic liver, the mesothelium, consisting of mesothelial cells and submesothelial cells, migrates inward from the liver surface and gives rise to HSCs and perivascular mesenchymal cells, including portal fibroblasts, smooth muscle cells around the portal vein, and fibroblasts around the central vein. Cell lineage analyses indicate that mesothelial cells are HSC progenitor cells capable of differentiating into HSCs and other liver mesenchymal cells during liver development.
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Affiliation(s)
- Kinji Asahina
- Southern California Research Center for ALPD and Cirrhosis and Department of Pathology, Keck School of Medicine of the University of Southern California
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Guyot C, Lepreux S, Combe C, Sarrazy V, Billet F, Balabaud C, Bioulac-Sage P, Desmoulière A. Fibrogenic cell phenotype modifications during remodelling of normal and pathological human liver in cultured slices. Liver Int 2010; 30:1529-40. [PMID: 20846345 DOI: 10.1111/j.1478-3231.2010.02342.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND The debate concerning the potential remodelling and/or reversibility of cirrhotic lesions and biliary fibrosis is still open. AIMS/METHODS In this work, we have used the precision-cut liver slice (PCLS) model, which maintains cell-cell and cell-matrix interactions to study, by immunohistochemistry, the behaviour of the different fibrogenic cells, i.e. hepatic stellate cells (HSC) and portal fibroblasts, in cultured (for 1 week) PCLS derived from normal and fibrotic human livers. RESULTS In normal liver, before and after culture, α-smooth muscle (SM) actin was present only in the vessel walls. Platelet-derived growth factor (PDGF) receptor-β was expressed before and after culture by portal fibroblasts, and appeared after culture in HSC. Before culture, CD 34 was not expressed in parenchyma, but appeared after culture in sinusoidal endothelial cells. In cirrhotic lesions, before culture, α-SM actin, PDGF receptor-β and Thy-1 were expressed in septa; after culture, α-SM actin expression disappeared but the expression of the PDGF receptor-β and Thy-1 was maintained. In cholestatic liver specimens, α-SM actin, PDGF receptor-β and Thy-1 expression, which was present before culture in enlarged portal areas, disappeared after culture, and apoptosis was detected. In the parenchyma of both cirrhotic and cholestatic livers, the expression of the PDGF receptor-β and of CD 34, which was not observed before culture, was present in HSC and sinusoidal endothelial cells, respectively, after culture. CONCLUSIONS These results indicate that during remodelling of pathological tissues in cultured liver slices, the myofibroblastic cells derived from HSC or from portal fibroblasts show different behaviours, suggesting different mechanisms of activation/deactivation.
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Affiliation(s)
- Christelle Guyot
- INSERM U889 and Université Victor Segalen Bordeaux 2, Bordeaux, France
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Abstract
UNLABELLED Portal fibroblasts are an important yet often overlooked nonparenchymal cell population in the liver. They are distinct from hepatic stellate cells, yet like stellate cells differentiate in the setting of chronic injury to fibrogenic myofibroblasts, playing an important role in collagen production in the fibrotic liver. Portal fibroblasts (PFs) are located adjacent to bile duct epithelia and thus play a particularly significant role in biliary fibrosis. New data suggest that they may also have key functions independent of fibrogenesis. This review addresses the definition and characteristics of PFs as well as their signaling pathways, interactions with the biliary epithelium, and contributions to liver pathobiology. CONCLUSION PFs are an important and multifunctional nonparenchymal cell population in need of further study.
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Affiliation(s)
- Jonathan A. Dranoff
- Department of Medicine (Digestive Diseases), Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520
| | - Rebecca G. Wells
- Department of Medicine (Gastroenterology), The University of Pennsylvania School of Medicine, 415 Curie Blvd., Philadelphia, PA, 19104
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Ayabe S, Murata T, Maruyama T, Hori M, Ozaki H. Prostaglandin E2 induces contraction of liver myofibroblasts by activating EP3 and FP prostanoid receptors. Br J Pharmacol 2009; 156:835-45. [PMID: 19239477 DOI: 10.1111/j.1476-5381.2008.00051.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND AND PURPOSE Increased portal pressure in liver injury results from hypercontraction of perivascular non-parenchymal cells including liver myofibroblasts (MFs). Prostaglandin E2 (PGE2) is the major eicosanoid which is released around the venous system during liver injury, but little is known about their contractile effect on MFs. EXPERIMENTAL APPROACH Contraction of primary rat liver MFs was measured by a collagen gel contraction assay. Expression of E prostanoid (EP) receptor subtypes was assessed by reverse transcription-polymerase chain reaction. Fura-2 fluorescence was used to determine intracellular Ca2+ concentration ([Ca2+](i)). Phosphorylation of protein kinase C (PKC) was detected by Western blot analysis. KEY RESULTS Liver MFs expressed mRNAs for all four EP receptors. PGE2 induced contraction in a dose- and time-dependent manner, and slightly increased [Ca2+](i) only at high concentrations (10 micromol.L(-1)). An agonist selective for EP(3) receptors, ONO-AE-248, dose-dependently induced MF contraction but did not increase [Ca2+](i). Pretreatment with rottlerin (a specific novel PKC inhibitor) and Ro 31-8425 (a general PKC inhibitor) significantly reduced 1 micromol.L(-1) PGE(2)- or ONO-AE-248-induced contractions. Furthermore, 1 micromol.L(-1) PGE(2) stimulated phosphorylation of PKC isoforms PKCdelta and PKCepsilon. The F prostanoid (FP) receptor antagonist AL8810 abolished the [Ca(2+)](i) elevation and the rapid contraction induced by 10 micromol.L(-1) PGE2. CONCLUSIONS AND IMPLICATIONS Lower concentrations up to 1 micromol.L(-1) of PGE2 induce liver MF contraction via a [Ca2+](i)-independent PKC-mediated pathway through the EP(3) receptor, while higher concentrations have an additional pathway leading to Ca(2+)-dependent contraction through activating the FP receptor.
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Affiliation(s)
- S Ayabe
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Tokyo, Japan
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11
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Ikeda H, Watanabe N, Ishii I, Shimosawa T, Kume Y, Tomiya T, Inoue Y, Nishikawa T, Ohtomo N, Tanoue Y, Iitsuka S, Fujita R, Omata M, Chun J, Yatomi Y. Sphingosine 1-phosphate regulates regeneration and fibrosis after liver injury via sphingosine 1-phosphate receptor 2. J Lipid Res 2008; 50:556-564. [PMID: 18955732 DOI: 10.1194/jlr.m800496-jlr200] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Sphingosine 1-phosphate (S1P), a bioactive lipid mediator, stimulates proliferation and contractility in hepatic stellate cells, the principal matrix-producing cells in the liver, and inhibits proliferation via S1P receptor 2 (S1P(2)) in hepatocytes in rats in vitro. A potential role of S1P and S1P(2) in liver regeneration and fibrosis was examined in S1P(2)-deficient mice. Nuclear 5-bromo-2'-deoxy-uridine labeling, proliferating cell nuclear antigen (PCNA) staining in hepatocytes, and the ratio of liver weight to body weight were enhanced at 48 h in S1P(2)-deficient mice after a single carbon tetrachloride (CCl(4)) injection. After dimethylnitrosamine (DMN) administration with a lethal dose, PCNA staining in hepatocytes was enhanced at 48 h and survival rate was higher in S1P(2)-deficient mice. Serum aminotransferase level was unaltered in those mice compared with wild-type mice in both CCl(4)- and DMN-induced liver injury, suggesting that S1P(2) inactivation accelerated regeneration not as a response to enhanced liver damage. After chronic CCl(4) administration, fibrosis was less apparent, with reduced expression of smooth-muscle alpha-actin-positive cells in the livers of S1P(2)-deficient mice, suggesting that S1P(2) inactivation ameliorated CCl(4)-induced fibrosis due to the decreased accumulation of hepatic stellate cells. Thus, S1P plays a significant role in regeneration and fibrosis after liver injury via S1P(2).
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Affiliation(s)
- Hitoshi Ikeda
- Department of Clinical Labo ratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan; Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
| | - Naoko Watanabe
- Department of Clinical Labo ratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan; Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Isao Ishii
- Department of Molecular and Cellular Neurobiology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Tatsuo Shimosawa
- Department of Clinical Labo ratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Yukio Kume
- Department of Clinical Labo ratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Tomoaki Tomiya
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Yukiko Inoue
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Takako Nishikawa
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Natsuko Ohtomo
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Yasushi Tanoue
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Satoko Iitsuka
- Department of Clinical Labo ratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Ryoto Fujita
- Department of Clinical Labo ratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Masao Omata
- Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
| | - Jerold Chun
- Department of Molecular Biology, Helen L. Dorris Child and Adolescent Neuropsychiatric Disorder Institute, The Scripps Research Institute, La Jolla, CA
| | - Yutaka Yatomi
- Department of Clinical Labo ratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
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12
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Dudas J, Mansuroglu T, Batusic D, Ramadori G. Thy-1 is expressed in myofibroblasts but not found in hepatic stellate cells following liver injury. Histochem Cell Biol 2008; 131:115-27. [PMID: 18797914 DOI: 10.1007/s00418-008-0503-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2008] [Indexed: 01/19/2023]
Abstract
Thy-1 (CD90) is an adhesion molecule induced in fibroblast populations associated with wound healing and fibrosis. In this study the question whether Thy-1-gene-expression can be induced in hepatic stellate cells (HSC) in vivo, under conditions of liver injury or liver regeneration was addressed. Acute and chronic rat liver injury was induced by the administration of CCl4. For comparison, cirrhotic human liver, and rat 67% partial hepatectomy (PH) was studied as well. Thy-1-gene-expression was examined also in isolated human liver myofibroblasts. Thy-1-mRNA expression was significantly upregulated in chronic liver injury. Thy-1+ cells were detected in the periportal area of rat liver specimens in normal-, injured- and regenerative-conditions. In chronic human and rat liver injury, Thy-1+ cells were located predominantly in scar tissue. In the pericentral necrotic zone after CCl4-treatment, no induction of Thy-1 was found. Gremlin and Thy-1 showed comparable localization in the periportal areas. Thy-1 was not detected in either normal or capillarized sinusoids, in isolated rat HSC, and was neither inducible by inflammatory cytokines in isolated HSC, nor upregulated in treated myofibroblasts. Based upon these data Thy-1 is not a marker of "activated" sinusoidal HSC, but it is a marker of "activated" (myo)fibroblasts found in portal areas and in scar tissue.
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Affiliation(s)
- Jozsef Dudas
- Department of Internal Medicine, Section of Gastroenterology and Endocrinology, Georg-August-University Göttingen, Robert-Koch-Strasse 40, 37075 Göttingen, Germany
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Maruyama T, Murata T, Ayabe S, Hori M, Ozaki H. Prostaglandin D(2) induces contraction via thromboxane A(2) receptor in rat liver myofibroblasts. Eur J Pharmacol 2008; 591:237-42. [PMID: 18586024 DOI: 10.1016/j.ejphar.2008.06.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Revised: 06/10/2008] [Accepted: 06/12/2008] [Indexed: 01/29/2023]
Abstract
Increased intrahepatic resistance is one of the major characteristics of cirrhotic liver, in which extravascular cells including liver myofibroblasts (MFs) abnormally contract. Although several studies provided evidence that various prostaglandins (PG) are involved in liver cirrhosis, the role of PGD(2) remains unknown. In this study, we investigated the effect of PGD(2) on the contractile properties of liver MFs. Cultured rat liver MFs were used at passages 4-7. A collagen gel contraction assay was used for the evaluation of the MFs contraction. mRNA expression was assessed by semi-quantitative RT-PCR. Intracellular Ca(2+) concentrations ([Ca(2+)](i)) were measured by monitoring the fluorescence intensity of fura-2. PGD(2) (1-10 microM) induced liver MF contraction in a dose-dependent manner with [Ca(2+)](i) elevation. Pretreatment with 300 nM LaCl(3), a nonselective Ca(2+) channel blocker abolished the 10 microM PGD(2)-induced MFs contraction. RT-PCR revealed that three distinct PGD(2) responsive receptors, prostanoid DP receptor, chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) and thromboxane A(2) receptor (prostanoid TP receptor), were expressed in liver MFs. While prostanoid DP receptor agonist and CRTH2 agonist didn't induce contraction, 0.01-1 microM U46619 (11alpha, 9alpha-epoxymethano-PGH(2), prostanoid TP receptor agonist) caused robust contraction with [Ca(2+)](i) elevation. Furthermore, pretreatment with prostanoid TP receptor antagonists ramatroban (1 microM) or SQ29548 ([1S-[1alpha, 2alpha(Z), 3alpha, 4alpha]]-7-[3-[[2-[(phenyl amino)carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid, 1 microM) completely suppressed PGD(2)-induced contraction and [Ca(2+)](i) elevation. Additionally, we observed that BW245C (1-10 microM) decreased basal MF contraction. These results suggest that PGD(2) induces rat liver MF contraction with an increase in [Ca(2+)](i) through prostanoid TP receptor.
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Affiliation(s)
- Tomoharu Maruyama
- Department of Veterinary Pharmacology, Agriculture and Life Science, The University of Tokyo, Japan
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14
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Aprigliano I, Dudas J, Ramadori G, Saile B. Atorvastatin induces apoptosis by a caspase-9-dependent pathway: an in vitro study on activated rat hepatic stellate cells. Liver Int 2008; 28:546-57. [PMID: 18339080 PMCID: PMC2324535 DOI: 10.1111/j.1478-3231.2008.01682.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Statins are shown to have cholesterol-independent properties such as anti-inflammation and immunomodulation. Activated hepatic stellate cells (HSCs) acquire the capacity to synthesize matrix proteins in damaged liver. We tested the hypothesis that atorvastatin may be capable of inducing apoptosis in HSCs. METHODS Primary cultures of rat HSCs were exposed to atorvastatin, mevalonic acid and U0126. Quantification of living, apoptotic and necrotic HSCs was performed by flow cytometry and laser-scan microscopy. Cell-cycle analysis was performed by flow cytometry. Pro- and anti-apoptotic factors were investigated by Western blot and electrophoresis mobility shift assay. Protease activity of caspases was calculated using a colorimetric kit. RESULTS Atorvastatin leads to a G2-arrest and induces apoptosis in activated HSCs. Atorvastatin-mediated apoptosis could be blocked by co-administration of mevalonic acid and U0126. No effects of atorvastatin on gene expression of CD95, CD95L, NF-kappaB, p53 and p21WAF1 could be observed. Atorvastatin-induced apoptosis in activated HSCs is related to an increased protease activity of caspase-9 and -3. Gene expression of the major proteins of the bcl-system shows that truncated Bid is involved in apoptosis mediated by atorvastatin. By blocking the extracellular signal-regulated protein kinase (ERK1/2) activation by adding U0126, we could prevent the apoptosis induced by atorvastatin. By Western blot we could not detect any change in the activation of c-jun N-terminal kinase (JNK). CONCLUSIONS Atorvastatin induces apoptosis in activated HSCs acting through an ERK-dependent cleavage of Bid and a highly increased protease activity of caspase-9 and -3. JNK is not involved in atorvastatin-mediated apoptosis in HSCs.
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Affiliation(s)
- Isabella Aprigliano
- Department of Internal Medicine, Section of Gastroenterology and Endocrinology, University of Göttingen, Göttingen, Germany
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15
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Barnaeva E, Nadezhda A, Hannappel E, Sjogren MH, Rojkind M. Thymosin beta4 upregulates the expression of hepatocyte growth factor and downregulates the expression of PDGF-beta receptor in human hepatic stellate cells. Ann N Y Acad Sci 2007; 1112:154-60. [PMID: 17584975 DOI: 10.1196/annals.1415.035] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Hepatic stellate cells (HSCs) are the main producers of type I collagen in the liver, and therefore are responsible, in part, for the fibrous scar observed in cirrhotic livers. Although there is no approved treatment for this deadly disease, drugs inducing HSC apoptosis in animals (gliotoxin) and hepatocyte regeneration in man (hepatocyte growth factor [HGF]), have been used successfully in ameliorating liver fibrosis. In this communication we investigated whether thymosin beta(4) (Tbeta(4)), an actin-sequestering peptide that prevents scarring of the heart after a myocardial infarction and that prevents kidney fibrosis in animals, has the potential to be used to treat liver fibrosis. To this end we studied whether the administration of Tbeta(4) to HSCs could alter the expression of genes encoding for extracellular matrix components, as well as those required for differentiation of HSCs. Our preliminary findings show that Tbeta(4) had no effect on the expression of alpha2 (I) collagen, tissue inhibitor of metalloproteinases-1, and matrix metalloproteinase-2 mRNAs. However, it upregulated the expression of HGF and downregulated the expression of platelet-derived growth factor-beta receptor mRNAs in these cells. Overall, these findings suggest that Tbeta(4) has antifibrogenic potential.
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Affiliation(s)
- Elena Barnaeva
- Department of Clinical Investigation, Walter Reed Army Medical Center, Washington, DC, USA
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16
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Dudas J, Mansuroglu T, Batusic D, Saile B, Ramadori G. Thy-1 is an in vivo and in vitro marker of liver myofibroblasts. Cell Tissue Res 2007; 329:503-14. [PMID: 17576600 DOI: 10.1007/s00441-007-0437-z] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Accepted: 05/09/2007] [Indexed: 12/26/2022]
Abstract
Thy-1, a glycophosphatidylinositol-linked glycoprotein of the outer membrane leaflet, has been described in myofibroblasts of several organs. Previous studies have shown that, in fetal liver, Thy-1 is expressed in a subpopulation of ductular/progenitor cells. The aim of this study has been to investigate whether the liver myofibroblasts belong to the Thy-1-positive subpopulation of the adult liver. The expression of Thy-1 has been studied in normal rat liver, in the rat liver regeneration model following 2-acetylaminofluorene treatment and partial hepatectomy (AAF/PH), and in isolated rat liver cells, at the mRNA and protein levels. In normal rat liver, Thy-1 is detected in sparse cells of the periportal area, whereas 7 days after PH in the AAF/PH model, a marked increase of the number of Thy-1-positive cells is detectable by immunohistochemistry. Comparative immunohistochemical analysis has revealed the co-localization of Thy-1 and smooth muscle actin, but not of Thy-1 and cytokeratin-19, both in normal rat liver and in the AAF/PH model. Investigation of isolated rat liver cell populations has confirmed that liver myofibroblasts are Thy-1-positive cells, whereas hepatocytes, hepatic stellate cells, and liver macrophages are not. Thy-1 is the first cell surface marker for identifying liver myofibroblasts in vivo and in vitro.
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Affiliation(s)
- Jozsef Dudas
- Department of Internal Medicine, Section of Gastroenterology and Endocrinology, Georg August University Göttingen, Robert-Koch-Strasse 40, 37075 Göttingen, Germany
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17
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Parekkadan B, van Poll D, Megeed Z, Kobayashi N, Tilles AW, Berthiaume F, Yarmush ML. Immunomodulation of activated hepatic stellate cells by mesenchymal stem cells. Biochem Biophys Res Commun 2007; 363:247-52. [PMID: 17869217 PMCID: PMC2096777 DOI: 10.1016/j.bbrc.2007.05.150] [Citation(s) in RCA: 177] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 05/23/2007] [Indexed: 01/06/2023]
Abstract
Bone marrow-derived mesenchymal stem cells (MSCs) have been reported to prevent the development of liver fibrosis in a number of pre-clinical studies. Marked changes in liver histopathology and serological markers of liver function have been observed without a clear understanding of the therapeutic mechanism by which stem cells act. We sought to determine if MSCs could modulate the activity of resident liver cells, specifically hepatic stellate cells (SCs) by paracrine mechanisms using indirect cocultures. Indirect coculture of MSCs and activated SCs led to a significant decrease in collagen deposition and proliferation, while inducing apoptosis of activated SCs. The molecular mechanisms underlying the modulation of SC activity by MSCs were examined. IL-6 secretion from activated SCs induced IL-10 secretion from MSCs, suggesting a dynamic response of MSCs to the SCs in the microenvironment. Blockade of MSC-derived IL-10 and TNF-alpha abolished the inhibitory effects of MSCs on SC proliferation and collagen synthesis. In addition, release of HGF by MSCs was responsible for the marked induction of apoptosis in SCs as determined by antibody-neutralization studies. These findings demonstrate that MSCs can modulate the function of activated SCs via paracrine mechanisms provide a plausible explanation for the protective role of MSCs in liver inflammation and fibrosis, which may also be relevant to other models of tissue fibrosis.
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Affiliation(s)
- Biju Parekkadan
- Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, 51 Blossom Street, Boston, Massachusetts 02114 USA
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, E-25, Cambridge, Massachusetts 02139 USA
| | - Daan van Poll
- Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, 51 Blossom Street, Boston, Massachusetts 02114 USA
| | - Zaki Megeed
- Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, 51 Blossom Street, Boston, Massachusetts 02114 USA
| | - Naoya Kobayashi
- Department of Surgery, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8558, Japan
| | - Arno W. Tilles
- Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, 51 Blossom Street, Boston, Massachusetts 02114 USA
| | - François Berthiaume
- Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, 51 Blossom Street, Boston, Massachusetts 02114 USA
| | - Martin L. Yarmush
- Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, 51 Blossom Street, Boston, Massachusetts 02114 USA
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, E-25, Cambridge, Massachusetts 02139 USA
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18
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Kojima N, Hori M, Murata T, Morizane Y, Ozaki H. Different profiles of Ca2+ responses to endothelin-1 and PDGF in liver myofibroblasts during the process of cell differentiation. Br J Pharmacol 2007; 151:816-27. [PMID: 17533428 PMCID: PMC2014126 DOI: 10.1038/sj.bjp.0707269] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND AND PURPOSE Hepatic stellate cells play an important role in liver fibrosis but little is known about liver myofibroblasts located around the central vein and in the portal area. In this study, intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured to assess the response to endothelin-1 (ET-1), platelet derived growth factor (PDGF) and ATP in rat liver myofibroblasts. EXPERIMENTAL APPROACH Rat liver myofibroblasts were compared in 'quiescent' (cultured on Matrigel-coated dishes) and 'activated' (cultured on non-coated plastic dishes) conditions. [Ca(2+)](i) was measured with the fluorescent dye fura-2 and mRNA for ET-1, PDGF and their receptors by RT-PCR. KEY RESULTS ET-1 increased [Ca(2+)](i) in quiescent cells but not in activated cells, whereas PDGF-BB increased [Ca(2+)](i) in activated cells but not in quiescent cells. However, there was no difference between responses to ATP in quiescent or activated cells. ET-1 (in quiescent cells), PDGF-BB (in activated cells) and ATP (in both cells) all induced transient increases in [Ca(2+)](i) in the absence of extracellular Ca(2+) (with EGTA), indicating the involvement of Ca(2+) release from intracellular Ca(2+) stores. The sustained increase in [Ca(2+)](i) in the presence of external Ca(2+) in activated cells (ATP and PDGF) was significantly reduced by nicardipine, a L-type Ca(2+) channel blocker, but not in quiescent cells (ATP and ET-1). CONCLUSIONS AND IMPLICATIONS The different pharmacological profiles of [Ca(2+)](i)-response in quiescent and activated myofibroblasts suggest that ET-1 and PDGF contribute differently to myofibroblast activation during the process of liver fibrosis.
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Affiliation(s)
- N Kojima
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo Bunkyo-ku, Tokyo, Japan
| | - M Hori
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo Bunkyo-ku, Tokyo, Japan
| | - T Murata
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo Bunkyo-ku, Tokyo, Japan
| | - Y Morizane
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo Bunkyo-ku, Tokyo, Japan
| | - H Ozaki
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo Bunkyo-ku, Tokyo, Japan
- Author for correspondence:
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19
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El-Karef A, Yoshida T, Gabazza EC, Nishioka T, Inada H, Sakakura T, Imanaka-Yoshida K. Deficiency of tenascin-C attenuates liver fibrosis in immune-mediated chronic hepatitis in mice. J Pathol 2007; 211:86-94. [PMID: 17121418 DOI: 10.1002/path.2099] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Tenascin-C (TNC), an extracellular matrix glycoprotein, is upregulated in chronic liver disease. Here, we investigated the contribution of TNC to liver fibrogenesis by comparing immune-mediated hepatitis in wild-type (WT) and TNC-null (TNKO) mice. Eight-week-old BALB/c mice received weekly intravenous injections of concanavalin A to induce hepatitis, and were sacrificed one week after the 3rd, 6th, 9th, and 12th injections. In WT livers, immunohistochemical staining revealed a gradual increase in TNC deposition. TNC mRNA levels also increased sequentially and peaked after the 9th injection. Collagen deposition, stained with picrosirius red, was significantly less intense in TNKO mice than in WT mice, and procollagen I and III transcripts were significantly upregulated in WT mice compared with TNKO mice. Inflammatory infiltrates were most prominent after the 3rd-6th injections in both groups and were less intense in TNKO mice than in WT mice. Interferon-gamma, tumour necrosis factor-alpha, and interleukin-4 mRNA levels were significantly higher in WT mice than in TNKO mice, while activated hepatic stellate cells (HSCs) and myofibroblasts, a cellular source of TNC and procollagens, were more common in WT livers. Transforming growth factor (TGF)-beta1 mRNA expression was significantly upregulated in WT mice, but not in TNKO mice. In conclusion, TNC can promote liver fibrogenesis through enhancement of inflammatory response with cytokine upregulation, HSC recruitment, and TGF-beta expression during progression of hepatitis to fibrosis.
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Affiliation(s)
- A El-Karef
- Department of Pathology and Matrix Biology, Graduate School of Medicine, Mie University, Mie, Japan
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20
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Guyot C, Combe C, Balabaud C, Bioulac-Sage P, Desmoulière A. Fibrogenic cell fate during fibrotic tissue remodelling observed in rat and human cultured liver slices. J Hepatol 2007; 46:142-50. [PMID: 17069927 DOI: 10.1016/j.jhep.2006.08.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2006] [Revised: 08/24/2006] [Accepted: 08/27/2006] [Indexed: 01/17/2023]
Abstract
BACKGROUND/AIMS Fibrotic liver remodelling was studied in culture of precision-cut liver slices (PCLS) derived from fibrotic liver. METHODS Fibrosis was induced in rats by carbon tetrachloride (CCl4) treatment or bile duct ligation. Human fibrotic livers were also used. PCLS were cultured for 6, 24, 48, or 72 h, and the expression of alpha-smooth muscle (SM) actin, platelet-derived growth factor (PDGF) receptor-beta, and active caspase 3 was studied by immunohistochemistry. RESULTS Before culture, in CCl4-treated or bile duct ligated animals, fibrosis was observed around centrolobular veins, or in portal zones, respectively. In PCLS derived from CCl4-treated animals, alpha-SM actin expression disappeared after 24h in culture while PDGF receptor-beta expression decreased progressively after 48 h. These changes were observed in absence of massive apoptosis. In PCLS derived from bile duct ligated animals, both alpha-SM actin and PDGF receptor-beta expression decreased after 48 h in culture with a massive apoptosis. In PCLS derived from human fibrotic livers, alpha-SM actin expression was dramatically reduced after 48 h in culture. CONCLUSIONS After CCl4 treatment, a proportion of myofibroblasts derived from hepatic stellate cells seems to dedifferentiate while in bile duct ligation model, myofibroblasts derived from portal fibroblasts disappear by apoptosis, underlining the relevance of this model to evaluate the mechanisms involved in fibrotic liver remodelling.
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Affiliation(s)
- Christelle Guyot
- INSERM, E0362, Université Victor Segalen Bordeaux 2, Bordeaux F-33076, France
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21
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Tátrai P, Dudás J, Batmunkh E, Máthé M, Zalatnai A, Schaff Z, Ramadori G, Kovalszky I. Agrin, a novel basement membrane component in human and rat liver, accumulates in cirrhosis and hepatocellular carcinoma. J Transl Med 2006; 86:1149-60. [PMID: 16983329 DOI: 10.1038/labinvest.3700475] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Agrin is a multifunctional heparan sulfate proteoglycan originally discovered in the neuromuscular junctions and later observed in numerous other localizations. The presence of agrin in the liver, either healthy or diseased, has formerly not been reported. We detected agrin in minor amounts in the basement membranes of blood vessels and bile ducts in the healthy liver. The proliferation of bile ductules and the formation of new septal blood vessels in liver cirrhosis, as well as neoangiogenesis in the hepatocellular carcinoma (HCC) result in a dramatic increase in the quantity of agrin. Vascular and peribiliary basement membranes were strongly immunopositive for agrin in 29/29 human liver specimens with cirrhosis and HCC. However, sinusoidal walls of regenerative nodules in the cirrhotic liver consistently remained negative. Given the selectivity of agrin for tumor microvessels, agrin immunohistochemistry may prove helpful in recognizing malignant transformation in cirrhotic livers. Similar immunohistochemical observations were made on the liver of rats exposed to a combined cirrhosis/HCC induction treatment. In both human and rats, agrin probably originates from activated myofibroblasts, vascular smooth muscle cells and biliary epithelial cells. Increased agrin expression in human specimens, in the liver of 4/4 treated rats, as well as in isolated rat liver mesenchymal cells was verified by quantitative RT-PCR. Considering that agrin binds various growth factors, and it directly interacts with cell membrane receptors such as alphav-integrins, we hypothesize a stimulatory role for agrin in neoangiogenic processes such as tumor vascularization, and a supportive role in bile ductule proliferation.
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MESH Headings
- Agrin/analysis
- Agrin/genetics
- Agrin/metabolism
- Animals
- Basement Membrane/chemistry
- Basement Membrane/metabolism
- Bile Ducts, Intrahepatic/metabolism
- Bile Ducts, Intrahepatic/pathology
- Carcinoma, Hepatocellular/blood supply
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Cell Proliferation
- Disease Models, Animal
- Fibroblasts/metabolism
- Fibroblasts/pathology
- Fluorescent Antibody Technique, Indirect
- Gene Expression Regulation, Neoplastic
- Humans
- Kupffer Cells/metabolism
- Kupffer Cells/pathology
- Liver/chemistry
- Liver/metabolism
- Liver/pathology
- Liver Cirrhosis/metabolism
- Liver Cirrhosis/pathology
- Liver Neoplasms/blood supply
- Liver Neoplasms/metabolism
- Liver Neoplasms/pathology
- Microcirculation/metabolism
- Microcirculation/pathology
- Muscle Cells/metabolism
- Muscle Cells/pathology
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- RNA, Messenger/metabolism
- Rats
- Tumor Cells, Cultured
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Affiliation(s)
- Péter Tátrai
- 11st Institute of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary.
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22
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Zhang Y, Ikegami T, Honda A, Miyazaki T, Bouscarel B, Rojkind M, Hyodo I, Matsuzaki Y. Involvement of integrin-linked kinase in carbon tetrachloride-induced hepatic fibrosis in rats. Hepatology 2006; 44:612-22. [PMID: 16941698 DOI: 10.1002/hep.21315] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Integrin-linked kinase (ILK) is a multidomain focal adhesion protein implicated in signal transduction between integrins and growth factor receptors. Although its expression is upregulated in pulmonary and renal fibrosis, its role in the development of hepatic fibrosis remains to be determined. Therefore, we considered it important to investigate whether ILK is involved in activation of hepatic stellate cells and thus plays a role in the development of hepatic fibrosis. Immunohistochemical analysis of liver sections obtained from rats with CCl4-induced cirrhosis revealed increased expression and colocalization of ILK and alpha-smooth muscle actin in hepatic stellate cells in perisinusoidal areas. In addition, hepatic stellate cells isolated from fibrotic livers expressed high levels of ILK and alpha-smooth muscle actin, and their expression was sustained in culture. In contrast, hepatic stellate cells (HSCs) isolated from normal rat liver did not express ILK, but its expression was increased when the cells were activated in culture. Our studies also showed that ILK is involved in the phosphorylation of ERK 1/2, p38 MAPK, JNK, and PKB and that selective inhibition of ILK expression by siRNA results in a significant decrease in their phosphorylation. These changes were accompanied by significant inhibition of cell spreading and migration without affecting cell proliferation. In conclusion, ILK plays a key role in HSC activation and could be a possible target for antifibrogenic therapy.
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Affiliation(s)
- Yining Zhang
- Graduate School of Comprehensive Human Science, University of Tsukuba, Tsukaba City, and Division of Gastroenterology and Hepatology, Tokyo Medical University Kasumigaura Hospital, Japan
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23
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Lafdil F, Chobert MN, Couchie D, Brouillet A, Zafrani ES, Mavier P, Laperche Y. Induction of Gas6 protein in CCl4-induced rat liver injury and anti-apoptotic effect on hepatic stellate cells. Hepatology 2006; 44:228-39. [PMID: 16799993 DOI: 10.1002/hep.21237] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The protein product of the growth arrest-specific gene 6 (Gas6) is a secreted ligand for tyrosine kinase receptors, among which Axl is the most widely distributed and displays the highest affinity for Gas6. The Gas6/Axl signaling pathway has been increasingly implicated in growth and survival processes occurring during development and tissue repair. In liver, after an acute or chronic injury, repair involves macrophages and hepatic stellate cells (HSC) activated into myofibroblastic cells (HSC/MFB), which produce cytokines and matrix proteins. We investigated the expression and the role of Gas6 and its receptor Axl in liver repair. Three days after CCl4-induced liver injury in the rat, we detected the expression of Gas6 in ED1-positive macrophages as well as in desmin-positive HSC, which accumulated in injured areas. Axl, the high-affinity receptor for Gas6, was detected in macrophages, HSC, and HSC/MFB. In vitro, expression of gamma-carboxylated Gas6 was strongly induced in HSC along with their transformation into myofibroblasts, and it exerted an anti-apoptotic effect on both HSC and HSC/MFB mediated by the Axl/PI3-kinase/Akt pathway. In conclusion, Gas6 is a survival factor for these cells and we suggest that Gas6, secreted by macrophages and HSC/MFB in vivo after liver injury, promotes HSC and HSC/MFB survival and might support transient HSC/MFB accumulation during liver healing.
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24
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Zhang LJ, Zheng WD, Shi MN, Wang XZ. Effects of interleukin-10 on activation and apoptosis of hepatic stellate cells in fibrotic rat liver. World J Gastroenterol 2006; 12:1918-23. [PMID: 16609999 PMCID: PMC4087518 DOI: 10.3748/wjg.v12.i12.1918] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To study the effects of interleukin-10 (IL-10) on the expression of α-smooth muscle actin (α-SMA), nuclear factor-κB(NF-κB) and Fas/Fas ligand (FasL) in hepatic stellate cells of experimental rats with hepatic fibrosis.
METHODS: Sixty clean SD rats were randomly divided into control group (group N), liver fibrotic group (group C) and IL-10 treatment group (group I). Control group received intraperitoneal injection of saline (2ml•kg-1), twice a week. Fibrotic group was injected intraperitoneally with 50% carbon tetrachloride (CCl4) (2 ml•kg-1), twice a week. IL-10 treatment group was given IL-10 at a dose of 4 µg•kg-1 20 minutes before CCl4 administration from the third week. Hepatic stellate cells (HSCs) were isolated from these rats at the seventh and eleventh weeks during the course of liver fibrosis, respectively. The expression of α-SMA and NF-κB in HSCs was measured by S-P immunohistochemistry. The expression of Fas and FasL mRNA was measured by RT-PCR. Furthermore, liver tissues were harvested from three groups at the same time.
RESULTS: The CCl4- induced experimental rat hepatic fibrosis model was established successfully. The purity of extracted hepatic stellate cells was about 95% and the yield of hepatic stellate cells was 1.2-2.3×106/g liver tissue averagely. The positive expression of α-SMA and NF-κB was 36.5% and 28.5% respectively in group N. The positive levels of α-SMA and NF-κB were increased significantly in group C compared to group N (P<0.01). The positive signals decreased significantly (P<0.05) in group I. In the 11th week, the HSCs of group I became round with visible pyknotic nuclei. The expression of NF-κB in group C was significantly increased in a time-dependentmanner (P<0.01), but there was no difference in the α-SMA expression (P >0.05). The mRNA of Fas and FasL in group C was significantly increased in a time-dependent manner compared to that in control group. After treated with IL-10, the expression level of Fas and FasL was higher in group I than in group C.
CONCLUSION: The positive expression of α-SMA and NF-κB in hepatic stellate cells is decreased by ectogenic IL-10 in liver fibrosis induced by CCl4. The expression of Fas and FasL is increased in the course of liver fibrosis, and is further increased by IL-10. IL-10 could inhibit the activation of HSCs and cause apoptosis of activated HSCs.
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Affiliation(s)
- Li-Juan Zhang
- Department of Gastroenterology, Union Hospital of Fujian Medical University, Fuzhou 350001, Fujian Province, China
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Elsharkawy AM, Oakley F, Mann DA. The role and regulation of hepatic stellate cell apoptosis in reversal of liver fibrosis. Apoptosis 2006; 10:927-39. [PMID: 16151628 DOI: 10.1007/s10495-005-1055-4] [Citation(s) in RCA: 311] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Liver fibrosis and its end-stage disease cirrhosis are major world health problems arising from chronic injury of the liver by a variety of etiological factors including viruses, alcohol and drug abuse, the metabolic syndrome, autoimmune disease and hereditary disorders of metabolism. Fibrosis is a progressive pathological process in which wound-healing myofibroblasts of the liver respond to injury by promoting replacement of the normal hepatic tissue with a scar-like matrix composed of cross-linked collagen. Until recently it was believed that this process was irreversible. However emerging experimental and clinical evidence is starting to show that even cirrhosis is potentially reversible. Key to this is the discovery that reversion of fibrosis is accompanied by clearance of hepatic stellate cells (HSC) by apoptosis. Furthermore, proof-of-concept studies in rodents have demonstrated that experimental augmentation of HSC apoptosis will promote the resolution of fibrosis. Consequently there is now considerable interest in determining the molecular events that regulate HSC apoptosis and the discovery of drugs that will stimulate HSC apoptosis in a selective manner. This review will consider the regulatory role played by growth factors (e.g. NGF, IGF-1, TGFbeta), death receptor ligands (TRAIL, FAS), components and regulators of extracellular matrix (integrins, collagen, matrix metalloproteinases and their tissue inhibitors) and signal transduction proteins and transcription factors (Rho/Rho kinase, Jun N-terminal Kinase (JNK), IkappaKinase (IKK), NF-kappa B). The potential for known pharmacological agents such as gliotoxin, sulfasalazine, benzodiazepine ligands, curcumin and tanshinone I to induce HSC apoptosis and therefore to be used therapeutically will be explored.
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Affiliation(s)
- A M Elsharkawy
- Liver Group, Division of Infection, Inflammation and Repair, University of Southampton, Southampton General Hospital, Level D, South Academic Block, Southampton, SO16 6YD, UK
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26
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Tsukada S, Parsons CJ, Rippe RA. Mechanisms of liver fibrosis. Clin Chim Acta 2005; 364:33-60. [PMID: 16139830 DOI: 10.1016/j.cca.2005.06.014] [Citation(s) in RCA: 275] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 06/07/2005] [Accepted: 06/08/2005] [Indexed: 01/18/2023]
Abstract
Liver fibrosis represents a significant health problem worldwide of which no acceptable therapy exists. The most characteristic feature of liver fibrosis is excess deposition of type I collagen. A great deal of research has been performed to understand the molecular mechanisms responsible for the development of liver fibrosis. The activated hepatic stellate cell (HSC) is the primary cell type responsible for the excess production of collagen. Following a fibrogenic stimulus, HSCs change from a quiescent to an activated, collagen-producing cell. Numerous changes in gene expression are associated with HSC activation including the induction of several intracellular signaling cascades, which help maintain the activated phenotype and control the fibrogenic and proliferative state of the cell. Detailed analyses in understanding the molecular basis of collagen gene regulation have revealed a complex process offering the opportunity for multiple potential therapeutic strategies. However, further research is still needed to gain a better understanding of HSC activation and how this cell maintains its fibrogenic nature. In this review we describe many of the molecular events that occur following HSC activation and collagen gene regulation that contribute to the fibrogenic nature of these cells and provide a review of therapeutic strategies to treat this disease.
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Affiliation(s)
- Shigeki Tsukada
- Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina at Chapel Hill, NC 27599-7032, USA
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Kim WH, Matsumoto K, Bessho K, Nakamura T. Growth inhibition and apoptosis in liver myofibroblasts promoted by hepatocyte growth factor leads to resolution from liver cirrhosis. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 166:1017-28. [PMID: 15793283 PMCID: PMC1602371 DOI: 10.1016/s0002-9440(10)62323-1] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Liver cirrhosis is characterized by hepatic dysfunction with extensive accumulation of fibrous tissue in the liver. In response to chronic hepatic injury, hepatic portal myofibroblasts and activated hepatic stellate cells (HSCs) play a role in liver fibrosis. Although administration or gene expression of hepatocyte growth factor (HGF) leads to improvement in hepatic fibrosis/cirrhosis, the related mechanisms are not fully understood. We investigated mechanisms involved in resolution from liver cirrhosis by HGF, focusing on growth regulation and apoptosis in portal myofibroblasts. Cultured rat HSCs could not proliferate, were withdrawn after passage, and were replaced by proliferating portal myofibroblasts during the passages. In quiescent HSCs, c-Met receptor expression was undetected whereas c-Met receptor expression was detected in activated HSCs and liver myofibroblasts expressing alpha-smooth muscle actin (alpha-SMA), suggesting that activated HSCs and portal myofibroblasts are targets of HGF. For cultured rat portal myofibroblasts, HGF counteracted phosphorylation of extracellular signal-regulated kinase (Erk) 1/2 and mitogenic stimulus induced by platelet-derived growth factor, induced c-jun N-terminal kinase (JNK) 1 phosphorylation, and promoted apoptotic cell death. In the dimethylnitrosamine rat model of liver cirrhosis, administration of HGF suppressed proliferation while promoting apoptosis of alpha-SMA-positive cells in the liver, events that were associated with reduced hepatic expressions of alpha-SMA and histological resolution from liver cirrhosis. Growth inhibition and enhanced apoptosis in portal myofibroblasts by HGF are newly identified mechanisms aiding resolution from liver fibrosis/cirrhosis by HGF.
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Affiliation(s)
- Wook-Hwan Kim
- Division of Molecular Regenerative Medicine, Course of Advanced Medicine, Osaka University Graduate School of Medicine, Yamada-oka 2-2-B7, Suita, Osaka 565-0871, Japan
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28
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Saile B, Eisenbach C, Dudas J, El-Armouche H, Ramadori G. Interferon-gamma acts proapoptotic on hepatic stellate cells (HSC) and abrogates the antiapoptotic effect of interferon-alpha by an HSP70-dependant pathway. Eur J Cell Biol 2005; 83:469-76. [PMID: 15540463 DOI: 10.1078/0171-9335-00409] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The activated hepatic stellate cell (HSC) is an important fibrogenic cell type of the liver. Interferon-alpha (IFN-alpha) has recently been shown to elicit an antiapoptotic effect on activated HSC by a JAK-2-dependent inhibition of caspase-8 activation. As JAK-2 has so far been shown to be a member of the IFN-gamma signal transduction pathway we studied the effect of IFN-gamma on apoptosis as well as on its signaling in primary cultured rat HSC. IFN-gamma elicited a proapoptotic effect in activated HSC. The combination of both, IFN-gamma and IFN-alpha, however, completely cancelled each other's effect. No effect of the two cytokines on major members of apoptosis-regulating systems (CD95, CD95L, bcl-2, bax, bcl-xL, p53, p21WAF1, p27, NFkappaB) could be observed. Western Blot analysis revealed that gene expression of the chaperone HSP70 was found to be downregulated by IFN-gamma but upregulated by IFN-alpha. The effect could be abrogated by administration of both. After transfection of activated HSC with a pCMV-HSP70 M expression vector the proapoptotic effect of IFN-gamma was cancelled. Using HSP70 antisense, the antiapoptotic effect of IFN-alpha was cancelled as well. However IFN-gamma had no effect on upregulation of JAK-2 and pJAK-2 by IFN-alpha. Taken together IFN-gamma and IFN-alpha exert opposite effects on apoptosis in HSC. This effect is mediated by their counteracting effect on HSP70 expression which acts antiapoptotic at the level of caspase-8.
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Affiliation(s)
- Bernhard Saile
- University of Göttingen, Department of Internal Medicine, Section of Gastroenterology and Endocrinology, Göttingen, Germany
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29
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Cheng CC, Yang SM, Huang CY, Chen JC, Chang WM, Hsu SL. Molecular mechanisms of ginsenoside Rh2-mediated G1 growth arrest and apoptosis in human lung adenocarcinoma A549 cells. Cancer Chemother Pharmacol 2005; 55:531-40. [PMID: 15739095 DOI: 10.1007/s00280-004-0919-6] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2004] [Accepted: 05/26/2004] [Indexed: 10/25/2022]
Abstract
Ginsenoside Rh2 (Rh2), a purified ginseng saponin, has been shown to have antiproliferative effects in certain cancer cell types. However, the molecular mechanisms of Rh2 on cell growth and death have not been fully clarified. In this study, the antiproliferative effect of Rh2 in human lung adenocarcinoma A549 cells was investigated. Treatment of A549 cells with 30 mug/ml Rh2 resulted in G(1) phase arrest, followed by progression to apoptosis. This Rh2-mediated G(1) arrest was accompanied by downregulation of the protein levels and kinase activities of cyclin-D1, cyclin-E and Cdk6, and the upregulation of pRb2/p130. In addition, Rh2-induced apoptosis was confirmed by TUNEL assay and DNA fragmentation analysis. Administration of Rh2 caused an increase in the expression levels of TRAIL-RI (DR4) death receptor but did not alter the levels of other death receptors or Bcl-2 family molecules. Furthermore, the Rh2-induced apoptosis was significantly inhibited by DR4:Fc fusion protein, which inhibits TRAIL-DR4-mediated apoptosis. In addition, caspase-2, caspase-3 and caspase-8 were highly activated upon Rh2 treatment. Inhibitors of caspase-2, caspase-3 and caspase-8 markedly prevented the cell death induced by Rh2. Inhibitor of caspase-8 significantly inhibited the activation of caspase-2, caspase-3 and caspase-8. These observations indicate that multiple G(1)-related cell cycle regulatory proteins are regulated by Rh2 and contribute to Rh2-induced G(1) growth arrest. The increase in the expression level of DR4 death receptor may play a critical role in the initiation of Rh2-triggered apoptosis, and the activation of the caspase-8/caspase-3 cascade acts as the executioner of the Rh2-induced death process.
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Affiliation(s)
- Chi-Chih Cheng
- Department of Education and Research, Taichung Veterans General Hospital, Taichung, 407, Taiwan
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Saile B, DiRocco P, Dudas J, El-Armouche H, Sebb H, Eisenbach C, Neubauer K, Ramadori G. IGF-I induces DNA synthesis and apoptosis in rat liver hepatic stellate cells (HSC) but DNA synthesis and proliferation in rat liver myofibroblasts (rMF). J Transl Med 2004; 84:1037-49. [PMID: 15156158 DOI: 10.1038/labinvest.3700116] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Several lines of evidence suggest a role of insulin-like growth factor I (IGF-I) in the regulation of apoptosis. Up to now its impact on many specific cells is unknown. We therefore studied the effect of IGF-I on two similar mesenchymal matrix-producing cell types of the liver, the hepatic stellate cells (HSC) and the myofibroblasts (rMF). The present study aimed to reveal the influence of IGF-I on cell cycle and apoptosis of HSC and rMF and to elucidate responsible signaling. While IGF-I significantly increased DNA synthesis in HSC, cell number decreased and apoptosis increased. In rMF IGF-I also increased DNA synthesis, which is, however, followed by proliferation. Blocking extracellular signal regulating kinase (ERK) revealed that in HSC, bcl-2 upregulation and bax downregulation are effected downstream of ERK, whereas downregulation of NFkappaB and consecutive of bcl-xL is mediated upstream. In the rMF upregulation of both, the antiapoptotic bcl-2 and bcl-xL is mediated upstream of ERK. The expression of the proapoptotic bax is not regulated by IGF-I in rMF. The studies demonstrate a completely different effect and signaling of IGF-I in two morphologically and functionally similar matrix-producing cells of the liver.
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Affiliation(s)
- Bernhard Saile
- Department of Internal Medicine, Section of Gastroenterology and Endocrinology, University of Göttingen, Göttingen, Germany
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Abstract
Progressive liver fibrosis is the main cause of organ failure in chronic liver diseases of any aetiology. Fibrosis develops with different spatial patterns and is a consequence of different prevalent mechanisms according to the diverse causes of parenchymal damage. Indeed, fibrosis, observed as a consequence of chronic viral infection is initially concentrated within and around the portal tract, while fibrosis secondary to toxic/metabolic damage is located mainly in the centrolobular areas. In addition, it is increasingly evident that different cell types are involved in the deposition of fibrillar extracellular matrix during active hepatic fibrogenesis: hepatic stellate cells are mainly involved when hepatocellular damage is limited or concentrated within the liver lobule, whereas portal myofibroblasts and fibroblasts provide a predominant contribution when the damage is located in the proximity of the portal tracts. In the later stages of evolution (septal fibrosis) it is likely that all extracellular matrix-producing cells contribute to fibrogenesis. Recruitment and activation of extracellular matrix-producing cells to the site of tissue damage can be due to different major mechanisms: (1) Chronic activation of the tissue repair process. In this case, as a consequence of the reiterated damage, accumulation of fibrillar extracellular matrix reflects the impossibility of an effective remodelling and regeneration. (2) Effect of oxidative stress products, including reactive oxygen intermediates and reactive aldehydes. These products, whose concentration become critical in toxic/metabolic liver injury, are able to induce the synthesis of fibrillar extracellular matrix even in the absence of significant hepatocyte damage and inflammation. (3) Derangement of normal the epithelial/mesenchymal interaction. This typically occurs in all conditions characterised by cholangiocyte damage/proliferation, where a consensual proliferation of extracellular matrix-producing cells and progressive fibrogenesis is commonly observed. A major advancement towards the understanding of the molecular mechanisms of fibrogenesis is derived from a consistent number of in vitro studies investigating the biological role of growth factors/cytokines and other soluble factors and their intracellular signalling pathways. The relevance of these factors has been confirmed by studies performed on animal models and by studies performed on pathological human liver. Along these lines, the elucidation of a consistent number of cellular and molecular mechanisms responsible for the progression of liver fibrosis has provided sound basis for the development of pharmacological strategies able to modulate this important pathophysiological process. Finally, there are several clinically relevant issues that need re-evaluation and/or further investigation, and in particular: (1) the need of an accurate and effective monitoring of the fibrotic progression of chronic liver diseases and of the effectiveness of the currently proposed treatments; (2) the identification of general or individual factors potentially relevant for a faster progression of the disease.
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Affiliation(s)
- M Pinzani
- Laboratory of Hepatology, Department of Internal Medicine, University of Florence, Viale G.B. Morgagni, 85, 50134 Florence, Italy.
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Abstract
The portal area is the 'main entrance' and one of the two main exits of the liver lobule. Through the main entrance portal and arterial blood reach the liver sinusoids. Through the exit the bile flows towards the duodenum. The three main structures, portal vein and artery with their own wall (and vascular smooth muscle cells) and bile duct with its basal membrane, are surrounded by loose myofibroblasts and by the first layer of hepatocytes and non-parenchymal cells. Chronic diseases of the liver can lead to development of liver cirrhosis, characterized by formation of fibrotic septa which can be portal-portal in the case of the chronic biliary damage or portal-central in the case of the chronic viral hepatitis. Central-central septa can also be observed under other pathological conditions. When damaging noxae are introduced to the liver, inflammatory cells are first recruited to the portal field, the first layer of hepatocytes may be destroyed (enlargement of the portal field) and portal (myo)fibroblasts become activated. A similar reaction may take place when the target of inflammation is the bile duct with consecutive reduction of the bile flow, activation of the portal (myo)fibroblasts, proliferation of bile ducts and destruction of the hepatocytes around the portal field. Increased matrix deposition may be the consequence. During the past years several publications dealt with the pathomechanisms of portal fibrogenesis as well as with its resolution. One of the most intriguing observations was that it is not hepatic stellate cells of the hepatic sinusoid, but portal (myo)fibroblasts which rapidly acquire the phenotype of 'activated' (myo)fibroblasts in the early stages of cholestatic fibrosis. These may also become the main mesenchymal cells of the porto-portal or porto-central fibrotic septa. This article reviews the similarities as well as differences between the mesenchymal cells of the portal tract and of the fibrotic septa vs 'activated' stellate cells of the hepatic sinusoids, and discusses the debate over their relative contributions to liver fibrogenesis.
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Affiliation(s)
- Giuliano Ramadori
- Department of Internal Medicine, Section of Gastroenterology and Endocrinology, University of Göttingen, Goettingen, Germany.
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33
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Abstract
The wall of the liver sinusoid is made of highly specialized cells, the hepatic stellate cells (HSC) which together with the sinusoidal endothelial cells represent a loose barrier to the corpusculate part of the blood flowing through the liver. Quiescent stellate cells (quiescent HSC) store Vitamin A; "activated" stellate cells become involved in the reaction to acute or chronic noxae damaging the liver parenchyma. Activated HSC show increased protein synthesis capacity, increased DNA-synthesis and acquire a myofibroblast-like phenotype. Under similar conditions liver myofibroblasts (MF) of the portal field and of the pericentral area may also become "activated" by increasing protein synthesis, DNA synthesis and cell division. They express the fibulin-2 gene and produce large amounts of IL-6. In contrast to "activated" HSC they do not undergo spontaneous apoptosis in vitro and do not express the CD95-ligand gene. So far no definite prove has been found for a "transdifferentiation" of HSC to myofibroblasts. On the contrary an increasing amount of data support the conviction that HSC and MF represent two similar but not identical cell populations the latter being comparable to those of other organs.
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Affiliation(s)
- G Ramadori
- Department of Internal Medicine, Section of Gastroenterology and Endocrinology, Georg-August University Göttingen, Robert-Koch-Strasse 40, 37075 Göttingen, Germany.
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