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Carter JK, Tsai MC, Venturini N, Hu J, Lemasters JJ, Torres Martin M, Sia D, Wang S, Lee YA, Friedman SL. Stellate cell-specific adhesion molecule protocadherin 7 regulates sinusoidal contraction. Hepatology 2024; 80:566-577. [PMID: 38373106 DOI: 10.1097/hep.0000000000000782] [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] [Received: 10/08/2022] [Accepted: 01/05/2024] [Indexed: 02/21/2024]
Abstract
BACKGROUND AND AIMS Sustained inflammation and hepatocyte injury in chronic liver disease activate HSCs to transdifferentiate into fibrogenic, contractile myofibroblasts. We investigated the role of protocadherin 7 (PCDH7), a cadherin family member not previously characterized in the liver, whose expression is restricted to HSCs. APPROACH AND RESULTS We created a PCDH7 fl/fl mouse line, which was crossed to lecithin retinol acyltransferase-Cre mice to generate HSC-specific PCDH7 knockout animals. HSC contraction in vivo was tested in response to the HSC-selective vasoconstrictor endothelin-1 using intravital multiphoton microscopy. To establish a PCDH7 null HSC line, cells were isolated from PCDH7 fl/fl mice and infected with adenovirus-expressing Cre. Hepatic expression of PCDH7 was strictly restricted to HSCs. Knockout of PCDH7 in vivo abrogated HSC-mediated sinusoidal contraction in response to endothelin-1. In cultured HSCs, loss of PCDH7 markedly attenuated contractility within collagen gels and led to altered gene expression in pathways governing adhesion and vasoregulation. Loss of contractility in PCDH7 knockout cells was impaired Rho-GTPase signaling, as demonstrated by altered gene expression, reduced assembly of F-actin fibers, and loss of focal adhesions. CONCLUSIONS The stellate cell-specific cadherin, PCDH7, is a novel regulator of HSC contractility whose loss leads to cytoskeletal remodeling and sinusoidal relaxation.
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Affiliation(s)
- James K Carter
- Department of Internal Medicine, Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Ming-Chao Tsai
- Department of Internal Medicine, Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Department of Internal Medicine, Division of Hepatogastroenterology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Nicholas Venturini
- Department of Internal Medicine, Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jiangting Hu
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - John J Lemasters
- Department of Drug Discovery and Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Miguel Torres Martin
- Genetics Department, Clinical Genomics Unit, Clinical Genetics Service, Germans Trias i Pujol University Hospital, Barcelona, Spain
| | - Daniela Sia
- Department of Internal Medicine, Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Shuang Wang
- Department of Internal Medicine, Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Youngmin A Lee
- Department of Internal Medicine, Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Department of Surgery, Section of Surgical Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Scott L Friedman
- Department of Internal Medicine, Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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Ferdek PE, Krzysztofik D, Stopa KB, Kusiak AA, Paw M, Wnuk D, Jakubowska MA. When healing turns into killing ‐ the pathophysiology of pancreatic and hepatic fibrosis. J Physiol 2022; 600:2579-2612. [DOI: 10.1113/jp281135] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 04/12/2022] [Indexed: 01/18/2023] Open
Affiliation(s)
- Pawel E. Ferdek
- Department of Cell Biology Faculty of Biochemistry Biophysics and Biotechnology Jagiellonian University Krakow Poland
| | - Daria Krzysztofik
- Malopolska Centre of Biotechnology Jagiellonian University Krakow Poland
| | - Kinga B. Stopa
- Malopolska Centre of Biotechnology Jagiellonian University Krakow Poland
| | - Agnieszka A. Kusiak
- Department of Cell Biology Faculty of Biochemistry Biophysics and Biotechnology Jagiellonian University Krakow Poland
| | - Milena Paw
- Department of Cell Biology Faculty of Biochemistry Biophysics and Biotechnology Jagiellonian University Krakow Poland
| | - Dawid Wnuk
- Department of Cell Biology Faculty of Biochemistry Biophysics and Biotechnology Jagiellonian University Krakow Poland
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Chan YT, Wang N, Tan HY, Li S, Feng Y. Targeting Hepatic Stellate Cells for the Treatment of Liver Fibrosis by Natural Products: Is It the Dawning of a New Era? Front Pharmacol 2020; 11:548. [PMID: 32425789 PMCID: PMC7212390 DOI: 10.3389/fphar.2020.00548] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 04/09/2020] [Indexed: 12/12/2022] Open
Abstract
Liver fibrosis is a progressive liver damage condition that is worth studying widely. It is important to target and alleviate the disease at an early stage before turning into later cirrhosis or liver cancer. There are currently no direct medicines targeting the attenuation or reversal of liver fibrosis, and so there is an urgent need to look into this area. Traditional Chinese Medicine has a long history in using herbal medicines to treat liver diseases including fibrosis. It is time to integrate the ancient wisdom with modern science and technology to look for the best solution to the disease. In this review, the principal concept of the pathology of liver fibrosis will be described, and then some of the single compounds isolated from herbal medicines, including salvianolic acids, oxymatrine, curcumin, tetrandrine, etc. will be discussed from their effects to the molecular mechanism behind. Molecular targets of the compounds are analyzed by network pharmacology approach, and TGFβ/SMAD was identified as the most common pathway. This review serves to summarize the current findings of herbal medicines combining with modern medicines in the area of fibrosis. It hopefully provides insights in further pharmaceutical research directions.
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Affiliation(s)
- Yau-Tuen Chan
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, Hong Kong
| | - Ning Wang
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, Hong Kong
| | - Hor Yue Tan
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, Hong Kong
| | - Sha Li
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, Hong Kong
| | - Yibin Feng
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, Hong Kong
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Cortes E, Lachowski D, Rice A, Chronopoulos A, Robinson B, Thorpe S, Lee DA, Possamai LA, Wang H, Pinato DJ, Del Río Hernández AE. Retinoic Acid Receptor-β Is Downregulated in Hepatocellular Carcinoma and Cirrhosis and Its Expression Inhibits Myosin-Driven Activation and Durotaxis in Hepatic Stellate Cells. Hepatology 2019; 69:785-802. [PMID: 30055117 DOI: 10.1002/hep.30193] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 07/25/2018] [Indexed: 01/17/2023]
Abstract
Hepatic stellate cells (HSCs) are essential perisinusoidal cells in both healthy and diseased liver. HSCs modulate extracellular matrix (ECM) homeostasis when quiescent, but in liver fibrosis, HSCs become activated and promote excess deposition of ECM molecules and tissue stiffening via force generation and mechanosensing. In hepatocellular carcinoma (HCC), activated HSCs infiltrate the stroma and migrate to the tumor core to facilitate paracrine signaling with cancer cells. Because the function of HSCs is known to be modulated by retinoids, we investigated the expression profile of retinoic acid receptor beta (RAR-β) in patients with cirrhosis and HCC, as well as the effects of RAR-β activation in HSCs. We found that RAR-β expression is significantly reduced in cirrhotic and HCC tissues. Using a comprehensive set of biophysical methods combined with cellular and molecular biology, we have elucidated the biomechanical mechanism by which all trans-retinoic acid promotes HSC deactivation via RAR-β-dependent transcriptional downregulation of myosin light chain 2 expression. Furthermore, this also abrogated mechanically driven migration toward stiffer substrates. Conclusion: Targeting mechanotransduction in HSCs at the transcriptional level may offer therapeutic options for a range of liver diseases.
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Affiliation(s)
- Ernesto Cortes
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Dariusz Lachowski
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Alistair Rice
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Antonios Chronopoulos
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Benjamin Robinson
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Stephen Thorpe
- School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom
| | - David A Lee
- School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom
| | - Lucia A Possamai
- Division of Integrative Systems Medicine and Digestive Disease, Imperial College London, London, United Kingdom
| | - Haiyun Wang
- School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - David J Pinato
- Department of Surgery and Cancer, Hammersmith Hospital Campus, Imperial College London, London, United Kingdom
| | - Armando E Del Río Hernández
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, United Kingdom
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Zhang Y, Zhao X, Chang Y, Zhang Y, Chu X, Zhang X, Liu Z, Guo H, Wang N, Gao Y, Zhang J, Chu L. Calcium channel blockers ameliorate iron overload-associated hepatic fibrosis by altering iron transport and stellate cell apoptosis. Toxicol Appl Pharmacol 2016; 301:50-60. [PMID: 27095094 DOI: 10.1016/j.taap.2016.04.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Revised: 03/24/2016] [Accepted: 04/07/2016] [Indexed: 02/07/2023]
Abstract
Liver fibrosis is the principal cause of morbidity and mortality in patients with iron overload. Calcium channel blockers (CCBs) can antagonize divalent cation entry into renal and myocardial cells and inhibit fibrogenic gene expression. We investigated the potential of CCBs to resolve iron overload-associated hepatic fibrosis. Kunming mice were assigned to nine groups (n=8 per group): control, iron overload, deferoxamine, high and low dose verapamil, high and low dose nimodipine, and high and low dose diltiazem. Iron deposition and hepatic fibrosis were measured in mouse livers. Expression levels of molecules associated with transmembrane iron transport were determined by molecular biology approaches. In vitro HSC-T6 cells were randomized into nine groups (the same groups as the mice). Changes in proliferation, apoptosis, and metalloproteinase expression in cells were detected to assess the anti-fibrotic effects of CCBs during iron overload conditions. We found that CCBs reduced hepatic iron content, intracellular iron deposition, the number of hepatic fibrotic areas, collagen expression levels, and hydroxyproline content. CCBs rescued abnormal expression of α1C protein in L-type voltage-dependent calcium channel (LVDCC) and down-regulated divalent metal transporter-1 (DMT-1) expression in mouse livers. In iron-overloaded HSC-T6 cells, CCBs reduced iron deposition, inhibited proliferation, induced apoptosis, and elevated expression of matrix metalloproteinase-13 (MMP-13) and tissue inhibitor of metalloproteinase-1 (TIMP-1). CCBs are potential therapeutic agents that can be used to address hepatic fibrosis during iron overload. They resolve hepatic fibrosis probably correlated with regulating transmembrane iron transport and inhibiting HSC growth.
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Affiliation(s)
- Ying Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China; Department of Pathology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China; Hebei Key Laboratory of Chinese Medicine Research on Cardio-Cerebrovascular Disease, Shijiazhuang 050200, Hebei, People's Republic of China
| | - Xin Zhao
- Department of Hepatobiliary Surgery, The Third Hospital of Hebei Medical University, Shijiazhuang 050051, Hebei, People's Republic of China
| | - Yanzhong Chang
- Laboratory of Molecular Iron Metabolism, College of Life Science, Hebei Normal University, Shijiazhuang 050024, Hebei, People's Republic of China
| | - Yuanyuan Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China
| | - Xi Chu
- Department of Pharmacy, The Forth Hospital of Hebei Medical University, Shijiazhuang 050011, Hebei, People's Republic of China
| | - Xuan Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China
| | - Zhenyi Liu
- Department of Medicinal Chemistry, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China
| | - Hui Guo
- Department of Medicinal Chemistry, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China
| | - Na Wang
- Department of Physiology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China
| | - Yonggang Gao
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China
| | - Jianping Zhang
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China.
| | - Li Chu
- Department of Pharmacology, Hebei University of Chinese Medicine, Shijiazhuang 050200, Hebei, People's Republic of China; Hebei Key Laboratory of Integrative Medicine on Liver-Kidney Patterns, Shijiazhuang 050200, Hebei, People's Republic of China.
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6
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Freise C, Heldwein S, Erben U, Hoyer J, Köhler R, Jöhrens K, Patsenker E, Ruehl M, Seehofer D, Stickel F, Somasundaram R. K⁺-channel inhibition reduces portal perfusion pressure in fibrotic rats and fibrosis associated characteristics of hepatic stellate cells. Liver Int 2015; 35:1244-52. [PMID: 25212242 DOI: 10.1111/liv.12681] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 09/03/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS In liver fibrosis, activated hepatic stellate cells (HSC) secrete excess extracellular matrix, thus, represent key targets for antifibrotic treatment strategies. Intermediate-conductance Ca(2) (+) -activated K(+) -channels (KCa3.1) are expressed in non-excitable tissues affecting proliferation, migration and vascular resistance rendering KCa3.1 potential targets in liver fibrosis. So far, no information about KCa3.1 expression and their role in HSC exists. Aim was to quantify the KCa3.1 expression in HSC depending on HSC activation and investigation of antifibrotic properties of the specific KCa3.1 inhibitor TRAM-34 in vitro and in vivo. METHODS KCa3.1 expression and functionality were studied in TGF-β1-activated HSC by quantitative real time PCR, western-blot and patch-clamp analysis respectively. Effects of TRAM-34 on HSC proliferation, cell cycle and fibrosis-related gene expression were assessed by [(3) H]-thymidine incorporation, FACS-analysis and RT-PCR respectively. In vivo, vascular resistance and KCa3.1 gene and protein expression were determined in bile duct ligated rats by in situ liver perfusion, Taqman PCR and immunohistochemistry respectively. RESULTS Fibrotic tissues and TGF-β1-activated HSC exhibited higher KCa3.1-expressions than normal tissue and untreated cells. KCa3.1 inhibition with TRAM-34 reduced HSC proliferation by induction of cell cycle arrest and reduced TGF-β1-induced gene expression of collagen I, alpha-smooth muscle actin and TGF-β1 itself. Furthermore, TRAM-34 blocked TGF-β1-induced activation of TGF-β signalling in HSC. In vivo, TRAM-34 reduced the thromboxane agonist-induced portal perfusion pressure. CONCLUSION Inhibition of KCa3.1 with TRAM-34 downregulates fibrosis-associated gene expression in vitro, and reduces portal perfusion pressure in vivo. Thus, KCa3.1 may represent novel targets for the treatment of liver fibrosis.
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Affiliation(s)
- Christian Freise
- Department of Gastroenterology, Infectiology and Rheumatology, Charité - University Medicine Berlin, Campus Benjamin Franklin, Berlin, Germany
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Calcium receptors located in fibrotic septa: a new target to reduce portal pressure in liver cirrhosis. Clin Sci (Lond) 2013; 125:67-75. [PMID: 23384153 DOI: 10.1042/cs20120476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In rats with experimental liver cirrhosis, the kidney contains reduced amounts of membrane-bound CaRs (calcium-sensing receptors), and the specific stimulation of CaRs causes the generation of PGE2 (prostaglandin E2), renal vasodilation and increased natriuresis. CaR content and function in the liver of cirrhotic rats are unknown. To assess the activity of this Ca2+-dependent vasomotor system, we evaluated the effects of intravenous administration of PolyAg (poly-L-arginine), a selective CaR agonist, on hormonal status, portal haemodynamics, MAP (mean arterial pressure) in rats with liver cirrhosis induced by chronic CCl4 (carbon tetrachloride) administration. Two groups of eight control rats received intravenously 1 ml of 5% (w/v) glucose solution alone or containing 0.5 mg of PolyAg; two groups of ten cirrhotic rats were administered vehicle or PolyAg. Compared with controls, at baseline cirrhotic rats showed higher portal pressure (P<0.01), lower estimated functional liver plasma flow, measured as CICG (Indocyanine Green clearance) (P<0.03) and reduced hepatic protein content of CaRs (P<0.03), which were located mainly in sub-endothelial layers of portal venules and in myofibroblasts of fibrotic septa (immunohistochemistry and indirect immunofluorescence staining of liver sections). In cirrhotic animals, 0.5 mg of PolyAg decreased portal pressure (P<0.01) and increased CICG (P<0.05), without effects on arterial pressure and hormonal status. In conclusion, the present study provides evidence that in experimental cirrhosis agonists of liver CaRs elicit beneficial portal hypotensive effects by reducing intrahepatic resistance to portal flow. Moreover, these drugs are devoid of effects on systemic haemodynamics.
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Salvianolic acid B lowers portal pressure in cirrhotic rats and attenuates contraction of rat hepatic stellate cells by inhibiting RhoA signaling pathway. J Transl Med 2012; 92:1738-48. [PMID: 22986787 DOI: 10.1038/labinvest.2012.113] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The contraction of hepatic stellate cells (HSCs) has a critical role in the regulation of intrahepatic vascular resistance and portal hypertension. Previous studies have confirmed that salvianolic acid B (Sal B) is effective against liver fibrosis. In the present study, we evaluated the effect of Sal B on portal hypertension and on HSCs contractility. Liver cirrhosis was induced in rats by peritoneal injection of dimethylnitrosamine and the portal pressure was measured. HSCs contraction was evaluated by collagen gel contraction assay. Glycerol-urea gel electrophoresis was performed to determine the phosphorylation of myosin light chain 2 (MLC2). F-actin stress fiber polymerization was detected by fluorescein isothiocyanate-labeled phalloidin. Intracellular Ca(2+) and RhoA signaling activation were also measured. Sal B effectively reduced the portal pressure in DMN-induced cirrhotic rats. It decreased the contraction by endothelin-1 (ET-1)-activated HSCs by ∼66.5% and caused the disassembly of actin stress fibers and MLC2 dephosphorylation. Although Sal B reduced ET-1-induced intracellular Ca(2+) increase, blocking Ca(2+) increase completely by BAPTA-AM, a Ca(2+) chelator, barely affected the magnitude of contraction. Sal B decreased ET-1-induced RhoA and Rho-associated coiled coil-forming protein kinase (ROCK) II activation by 66.84% and by 76.79%, respectively, and inhibited Thr(696) phosphorylation of MYPT1 by 80.09%. In vivo, Sal B lowers the portal pressure in rats with DMN-induced cirrhosis. In vitro, Sal B attenuates ET-1-induced HSCs contraction by inhibiting the activation of RhoA and ROCK II and the downstream MYPT1 phosphorylation at Thr(696). We consider Sal B a potential candidate for the pharmacological treatment of portal hypertension.
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Ohyama T, Sato K, Kishimoto K, Yamazaki Y, Horiguchi N, Ichikawa T, Kakizaki S, Takagi H, Izumi T, Mori M. Azelnidipine is a calcium blocker that attenuates liver fibrosis and may increase antioxidant defence. Br J Pharmacol 2012; 165:1173-87. [PMID: 21790536 DOI: 10.1111/j.1476-5381.2011.01599.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Oxidative stress plays a critical role in liver fibrogenesis. Reactive oxygen species (ROS) stimulate hepatic stellate cells (HSCs), and ROS-mediated increases in calcium influx further increase ROS production. Azelnidipine is a calcium blocker that has been shown to have antioxidant effects in endothelial cells and cardiomyocytes. Therefore, we evaluated the anti-fibrotic and antioxidative effects of azelnidipine on liver fibrosis. EXPERIMENTAL APPROACH We used TGF-β1-activated LX-2 cells (a human HSC line) and mouse models of fibrosis induced by treatment with either carbon tetrachloride (CCl(4) ) or thioacetamide (TAA). KEY RESULTS Azelnidipine inhibited TGF-β1 and angiotensin II (Ang II)-activated α1(I) collagen mRNA expression in HSCs. Furthermore, TGF-β1- and Ang II-induced oxidative stress and TGF-β1-induced p38 and JNK phosphorylation were reduced in HSCs treated with azelnidipine. Azelnidipine significantly decreased inflammatory cell infiltration, pro-fibrotic gene expressions, HSC activation, lipid peroxidation, oxidative DNA damage and fibrosis in the livers of CCl(4) - or TAA-treated mice. Finally, azelnidipine prevented a decrease in the expression of some antioxidant enzymes and accelerated regression of liver fibrosis in CCl(4) -treated mice. CONCLUSIONS AND IMPLICATIONS Azelnidipine inhibited TGF-β1- and Ang II-induced HSC activation in vitro and attenuated CCl(4) - and TAA-induced liver fibrosis, and it accelerated regression of CCl(4) -induced liver fibrosis in mice. The anti-fibrotic mechanism of azelnidipine against CCl(4) -induced liver fibrosis in mice may have been due an increased level of antioxidant defence. As azelnidipine is widely used in clinical practice without serious adverse effects, it may provide an effective new strategy for anti-fibrotic therapy.
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Affiliation(s)
- T Ohyama
- Departments of Medicine and Molecular Science Biochemistry, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan
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Liu Z, van Grunsven LA, Van Rossen E, Schroyen B, Timmermans JP, Geerts A, Reynaert H. Blebbistatin inhibits contraction and accelerates migration in mouse hepatic stellate cells. Br J Pharmacol 2009; 159:304-15. [PMID: 20039876 DOI: 10.1111/j.1476-5381.2009.00477.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Blebbistatin, an inhibitor of myosin-II-specific ATPase, has been used to inhibit contraction of invertebrate and mammalian muscle preparations containing non-muscle myosin. Activated hepatic stellate cells have contractile properties and play an important role in the pathophysiology of liver fibrosis and portal hypertension. Therefore, hepatic stellate cells are considered as therapeutic target cells. In the present study, we studied the effect of blebbistatin during the transition of mouse hepatic stellate cells into contractile myofibroblasts. EXPERIMENTAL APPROACH Effects of blebbistatin on cell morphology were evaluated by phase contrast microscopy. Cell stress fibres and focal adhesions were investigated by dual immunofluorescence staining and visualized using fluorescence microscopy. Contractile force generation was examined by silicone wrinkle formation assays and collagen gel contraction assays. Intracellular Ca(2+) release in response to endothelin-1 was measured by using Fluo-4. Cell migration was measured by wound healing experiments. KEY RESULTS In culture-activated hepatic stellate cells, blebbistatin was found to change both cell morphology and function. In the presence of blebbistatin, stellate cells became smaller, acquired a dendritic morphology and had less myosin IIA-containing stress fibres and vinculin-containing focal adhesions. Moreover, blebbistatin impaired silicone wrinkle formation, reduced collagen gel contraction and blocked endothelin-1-induced intracellular Ca(2+) release. Finally, it promoted wound-induced cell migration. CONCLUSIONS AND IMPLICATIONS By inhibiting myosin II ATPase, blebbistatin has profound effects on the morphology and function of activated hepatic stellate cells. Our data suggest that myosin II could be a therapeutic target in the treatment of liver fibrosis and portal hypertension.
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Affiliation(s)
- Zhenan Liu
- Department of Cell Biology, Vrije Universiteit Brussel, Brussels, Belgium
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Lee JS, Kim JH. [The role of activated hepatic stellate cells in liver fibrosis, portal hypertension and cancer angiogenesis]. THE KOREAN JOURNAL OF HEPATOLOGY 2008; 13:309-19. [PMID: 17898548 DOI: 10.3350/kjhep.2007.13.3.309] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Although hepatic stellate cells, which are liver specific pericytes, have been recognized within the vasculature of the sinusoid for more than one hundred years, the biology and function of these cells is unclear. Recent studies have highlighted the key role of stellate cells in a number of fundamental processes that include wound healing/fibrosis, vasoregulation, and vascular remodeling/angiogenesis. In the liver, these processes are particularly important in the development of cirrhosis, portal hypertension and cancer. This article highlights the recent advances in our understanding of the biology of hepatic stellate cells and discusses some of the recently-ascribed functions that are relevant to liver fibrosis, portal hypertension and cancer angiogenesis.
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Affiliation(s)
- June Sung Lee
- Department of Internal Medicine, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Korea.
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12
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Soon RK, Yee HF. Stellate cell contraction: role, regulation, and potential therapeutic target. Clin Liver Dis 2008; 12:791-803, viii. [PMID: 18984467 PMCID: PMC2600510 DOI: 10.1016/j.cld.2008.07.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The contraction of hepatic stellate cells has been proposed to mediate fibrosis by regulating sinusoidal blood flow and extracellular matrix remodeling. Abundant data from diverse, yet complementary, experimental methods support a robust model for the regulation of contractile force generation by stellate cells. In this model, soluble factors associated with liver injury, including endothelin 1 and nitric oxide, are transduced primarily through Rho signaling pathways that promote the myosin II-powered generation of contractile force by stellate cells. The enhanced knowledge of the role and differential regulation of stellate cell contraction may facilitate the discovery of new and targeted strategies for the prevention and treatment of hepatic fibrosis.
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Affiliation(s)
- Russell K. Soon
- Research Associate, Department of Medicine and Liver Center, University of California, San Francisco, San Francisco, California
| | - Hal F. Yee
- William and Mary Ann Rice Memorial Distinguished Professor, Department of Medicine and Liver Center, University of California San Francisco; Chief of Gastroenterology and Hepatology, San Francisco General Hospital; San Francisco, California
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Abdeen SM, Olusi SO, Askar HA, Thalib L, Al-Azemi A, George S. The predictive value of CD38 positive hepatic stellate cell count for assessing disease activity and fibrosis in patients with chronic hepatitis. Acta Histochem 2008; 111:520-30. [PMID: 18829073 DOI: 10.1016/j.acthis.2008.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2008] [Revised: 04/03/2008] [Accepted: 04/03/2008] [Indexed: 01/19/2023]
Abstract
The activation of hepatic stellate cells (HSCs) is a critical event in hepatic fibrosis. The objectives of this study were to find out if cluster of differentiation 38 (CD38) can be demonstrated immunohistochemically on HSCs in liver biopsies from patients with chronic liver disease and if CD38 immunopositive HSC count is correlated with METAVIR inflammatory and fibrosis scores. Immunohistochemical labelling for CD38 was performed on 100 liver biopsies from patients with chronic liver disease. The CD38 immunopositive HSCs were identified and counted. The CD38 immunopositive HSC count was found to be associated with both the METAVIR score and the fibrosis scores. The CD38 immunopositive HSC count was able to discriminate between no fibrosis and stages 2, 3 or 4 fibrosis, but could not discriminate between no fibrosis and stage 1 fibrosis. Using receiver operating characteristic (ROC) curves, a cut-off point of 10 HSCs per 10 high power field (hpf), or 25 per 100 hepatocytes, is 80% sensitive and 70% specific for predicting fibrosis. The specificity rose to 100% in patients with hepatitis C viral (HCV) infection. We conclude that CD38 positive HSCs can be demonstrated immunohistochemically and that the count is highly predictive of moderate to severe hepatic fibrosis.
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Abstract
PURPOSE This study examined the expression and function of inward rectifier K(+) channels in cultured rat hepatic stellate cells (HSC). MATERIALS AND METHODS The expression of inward rectifier K(+) channels was measured using real-time RT-PCR, and electrophysiological properties were determined using the gramicidin-perforated patch-clamp technique. RESULTS The dominant inward rectifier K(+) channel subtypes were K(ir)2.1 and K(ir)6.1. These dominant K(+) channel subtypes decreased significantly during the primary culture throughout activation process. HSC can be classified into two subgroups: one with an inward-rectifying K(+) current (type 1) and the other without (type 2). The inward current was blocked by Ba(2+) (100 microM) and enhanced by high K(+) (140 mM), more prominently in type 1 HSC. There was a correlation between the amplitude of the Ba(2+)-sensitive current and the membrane potential. In addition, Ba(2+) (300 microM) depolarized the membrane potential. After the culture period, the amplitude of the inward current decreased and the membrane potential became depolarized. CONCLUSION HSC express inward rectifier K(+) channels, which physiologically regulate membrane potential and decrease during the activation process. These results will potentially help determine properties of the inward rectifier K(+) channels in HSC as well as their roles in the activation process.
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Affiliation(s)
- Dong Hyeon Lee
- Department of Physiology, College of Medicine, Pochon CHA University, Seongnam, Gyeonggi-do, Korea
| | - In Deok Kong
- Department of Physiology and Institute of Lifelong Health, Yonsei University Wonju College of Medicine, Wonju, Gangwon-do, Korea
| | - Joong-Woo Lee
- Department of Physiology and Institute of Lifelong Health, Yonsei University Wonju College of Medicine, Wonju, Gangwon-do, Korea
| | - Kyu-Sang Park
- Department of Physiology and Institute of Lifelong Health, Yonsei University Wonju College of Medicine, Wonju, Gangwon-do, Korea
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15
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Reynaert H, Urbain D, Geerts A. Regulation of sinusoidal perfusion in portal hypertension. Anat Rec (Hoboken) 2008; 291:693-8. [PMID: 18484616 DOI: 10.1002/ar.20669] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Portal hypertension, a major complication of cirrhosis, is caused by both increased portal blood flow and augmented intrahepatic vascular resistance. Even though the latter is primarily caused by anatomical changes, it has become clear that dynamic factors contribute to the increased hepatic vascular resistance. The hepatic sinusoid is the narrowest vascular structure within the liver and is the principal site of blood flow regulation. The anatomical location of hepatic stellate cells, which embrace the sinusoids, provides a favorable arrangement for sinusoidal constriction, and for control of sinusoidal vascular tone and blood flow. Hepatic stellate cells possess the essential contractile apparatus for cell contraction and relaxation. Moreover, the mechanisms of stellate cell contraction are better understood, and many substances which influence contractility have been identified, providing a rationale and opportunity for targeting these cells in the treatment of portal hypertension in cirrhosis.
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Affiliation(s)
- Hendrik Reynaert
- Department of Cell Biology, Vrije Universiteit Brussel, Brussel, Brussels, Belgium.
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Leung TM, Tipoe GL, Liong EC, Lau TYH, Fung ML, Nanji AA. Endothelial nitric oxide synthase is a critical factor in experimental liver fibrosis. Int J Exp Pathol 2008; 89:241-50. [PMID: 18429990 DOI: 10.1111/j.1365-2613.2008.00590.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Reduced expression of endothelial nitric oxide synthase (eNOS) in chronic liver disease can reduce hepatic perfusion and accelerate fibrosis. The relationship between eNOS expression and liver fibrogenesis remains unclear. We investigated whether L-arginine attenuated chronic liver fibrosis through eNOS expression. Chronic liver injury was induced by administration of carbon tetrachloride (CCl(4)) to mice for 8 weeks. 5-Methylisothiourea hemisulphate (SMT), an iNOS inhibitor, or L-arginine, a NOS substrate were injected subcutaneously. CCl(4)-induced hepatotoxicity, oxidative stress and accumulation of collagen were detected in the liver. The expression levels of inducible NOS (iNOS) and nuclear factor kappa-B (NF-kappaB) activity in the liver after CCl(4) treatment were increased but eNOS expression and activator protein-1 (AP-1) activity were decreased. Both SMT and L-arginine effectively reduced CCl(4) induced oxidative stress and collagen formation, but L-arginine showed a significantly greater suppression of collagen formation, iNOS expression and NF-kappaB activity. L-arginine also restored the level of eNOS and AP-1 activity. L-arginine was more effective than SMT in suppressing liver fibrosis. L-arginine might improve NO production which facilitates hepatic blood flow and thus retards liver fibrogenesis. Our results showed that the reduced eNOS expression in CCl(4)-treated mice was reversed by L-arginine. Furthermore, L-arginine also reversed the reduced AP-1 activity, an eNOS promoter.
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Affiliation(s)
- Tung-Ming Leung
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
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17
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Chen Y, Wang CP, Lu YY, Zhou L, Su SH, Jia HJ, Feng YY, Yang YP. Hepatic stellate cells may be potential effectors of platelet activating factor induced portal hypertension. World J Gastroenterol 2008; 14:218-23. [PMID: 18186558 PMCID: PMC2675117 DOI: 10.3748/wjg.14.218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To determine platelet activating factor (PAF) receptor expression in cirrhotic hepatic stellate cells.
METHODS: Hepatic stellate cells, isolated from the livers of control and CCl4-induced cirrhotic rats, were placed in serum-free medium after overnight culture. We determined the PAF receptor in hepatic stellate cells by saturation binding technique and semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), and the effects of PAF and its antagonist BN52021 on prostaglandin E2 (PGE2) release by stellate cells.
RESULTS: Scatchard analysis indicated the presence of PAF receptor with dissociation constant (Kd) of 4.66 nmol/L and maximum binding capacity (Bmax) of 24.65 fmol/&mgr;g in cirrhotic stellate cells. Compared with the control, the maximum PAF binding capacity increased significantly (Bmax: 24.65 ± 1.96 fmol/&mgr;g. DNA, R = 0.982 vs 5.74 ± 1.55 fmol/&mgr;g. DNA, R = 0.93; P < 0.01), whereas receptor affinity had no significant difference (Kd of 4.66 ± 0.33 nmol/L for the cirrhosis and 3.51 ± 0.26 nmol/L for the control; P > 0.05). Consistent with the receptor binding data, the mRNA expression of PAF receptor was increased significantly in cirrhotic stellate cells. PAF in a concentration-dependent manner induced PGE2 synthesis in cirrhotic hepatic stellate cells, but the effects were blocked significantly by BN52021.
CONCLUSION: Cirrhosis sensitizes hepatic stellate cells to PAF by elevating its receptor level and hepatic stellate cells maybe potential effectors of PAF induced portal hypertension.
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Yang KL, Chang WT, Chuang CC, Hung KC, Li EIC. Antagonizing TGF-beta induced liver fibrosis by a retinoic acid derivative through regulation of ROS and calcium influx. Biochem Biophys Res Commun 2007; 365:484-9. [PMID: 17997979 DOI: 10.1016/j.bbrc.2007.10.203] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 10/31/2007] [Indexed: 01/19/2023]
Abstract
Transforming growth factor-beta1 (TGF-beta1) mediates the regulation of extracellular matrix via reactive oxygen species (ROS) and calcium influx, both are activators of hepatic stellate cells (HSC) which play a critical role in hepatic fibrogenesis. Hence one can use ROS assay as the main screening tool for molecules that might antagonize the process of liver fibrosis. A retinoic acid derivative isolated from the mycelium of Phellinus linteus that down-regulates ROS generation and calcium influx in HSC-T6 cells was thus obtained in our screening process. The retinoic acid derivative also reverses an early liver fibrosis, as assayed by liver contents of hydroxyproline, alpha-smooth muscle actin (alpha-SMA), and collagen 1A2, in an early liver fibrosis model we established previously where an inducible expression vector containing a TGF-beta gene was hydrodynamically transferred into a testing animal. Retinoic acid derivative thus acts both in vitro and in vivo to prevent liver fibrosis at an early phase.
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Affiliation(s)
- Kun-Lin Yang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan
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19
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Abstract
Recent studies have shown that the renin-angiotensin system (RAS) plays a pivotal role in liver fibrosis. An intrahepatic RAS is expressed in chronically damaged livers, and angiotensin-II (AT-II) reportedly stimulates contraction and proliferation of the activated hepatic stellate cells (Ac-HSC), and increases the transforming growth factor-beta (TGF-beta) expression through angiotensin type-I receptors (AT1-R). Some studies have demonstrated that the clinically used angiotensin-converting enzyme (ACE) inhibitor (ACE-I), and AT1-R blockers (ARB) significantly attenuated experimental liver fibrosis along with suppression of the Ac-HSC and hepatic TGF-beta expression. Angiotensin-II also stimulates the tissue inhibitor of metalloproteinases-1 (TIMP-1) in a dose- and time-dependent manner via protein kinase-C as an intracellular signaling cascade in the Ac-HSC, and these effects are completely suppressed by ARB. Combination treatment with low-dose interferon (IFN) and ACE-I exerts a stronger inhibitory effect than either single agent on its own. In humans it has been reported that ARB markedly improved the liver fibrosis score and TGF-beta expression in patients with chronic hepatitis C and non-alcoholic steatohepatitis. Serum fibrosis markers also significantly improved by treatment with low-dose IFN and ACE-I in patients with chronic hepatitis C, refractory to IFN monotherapy. Collectively, these data suggest that the interaction between AT-II and AT1-R plays a pivotal role in liver fibrosis development. Because both ACE-I and ARB are widely used in clinical practice without serious side-effects, these drugs in combination with IFN may provide a new strategy for antifibrosis therapy.
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Affiliation(s)
- Hitoshi Yoshiji
- Third Department of Internal Medicine, Nara Medical University, Nara, Japan.
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20
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March S, Graupera M, Rosa Sarrias M, Lozano F, Pizcueta P, Bosch J, Engel P. Identification and functional characterization of the hepatic stellate cell CD38 cell surface molecule. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 170:176-87. [PMID: 17200192 PMCID: PMC1762705 DOI: 10.2353/ajpath.2007.051212] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The activation of hepatic stellate cells (HSCs) is a critical event in hepatic fibrosis, because these cells are the main producers of extracellular matrix proteins in the liver and contribute to the modulation of inflammatory responses via the secretion of several cytokines and the expression of adhesion molecules. The goal of the present study was to characterize cell surface proteins that regulate HSC activation. To this end, a panel of monoclonal antibodies (mAbs) was generated. mAb 14.27 recognized a protein of 45 kd that was highly expressed on HSCs. Affinity purification of this protein followed by sequencing revealed that protein to be CD38. We subsequently demonstrated that CD38 was constitutively expressed by HSCs and that its expression increased after in vitro and in vivo activation. mAb 14.27 induced an increase in cytosolic Ca2+ levels in HSCs, showing that it functions as an agonistic antibody. Moreover, the effects mediated by the CD38 mAb included induction of the proinflammatory cytokine interleukin-6 and up-regulation of the adhesion molecules intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and neural cell adhesion molecule. Collectively, our data suggest that CD38 can act as a regulator of HSC activation and effector functions.
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Affiliation(s)
- Sandra March
- Immunology Unit, Department of Cellular Biology and Pathology, Medical School, University of Barcelona, Barcelona, Spain
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21
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Yao DM, Fang SM, Yang CJ, Xiu HM, Su SW, Yao XX. Effects of radix salviae miltiorrhizae on endothelin-1-induced calcium changes in hepatic stellate cells. Shijie Huaren Xiaohua Zazhi 2006; 14:2488-2492. [DOI: 10.11569/wcjd.v14.i25.2488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of radix salviae miltiorrhizae (RSM) on the changes of [Ca2+]i induced by endothelin-1 (ET-1) in hepatic stellate cells (HSCs).
METHODS: After preparation of RSM cream, the effects of RSM on ET-1-induced changes of HSCs [Ca2+]i were observed by laser scanning confocal microscopy.
RESULTS: In normal buffer (including Ca2+, buffer A), the fluorescence intensity was enhanced accordingly with the increase of ET-1 concentration. The cumulative-response curve showed EC50 was 1.1×10-9 mol/L. After incubation of HSCs with ET-1 in buffer A and buffer B (absence of extracellular calcium, EGTA), the duration of calcium peak had significant difference (165.2 ± 10.1 s vs 91.0 ± 7.2 s, P < 0.01), while the value of calcium peak had no significant difference. The ET-1-induced duration of calcium wave decreased markedly in the cells pretreated with RSM in buffer A as compared with that in the ones treated by ET-1 alone (69.1 ± 12.5 s vs 165.2 ± 10.1 s, P < 0.01). The calcium peak value and duration of calcium wave had no significant changes between the cells pre-incubated with RSM in buffer B and A (P > 0.05). In the cells pre-incubated with RSM, KCl-induced elevation of [Ca2+]i was decreased, and the calcium peak value (78.0% ± 6.1% → 26.3% ± 1.2%, P < 0.01) and duration of calcium wave (70.8 ± 10.4 s → 15.9 ± 5.1 s, P < 0.01) were decreased significantly.
CONCLUSION: RSM inhibits ET-1-induced depletion of intracellular calcium, which has no correlations with the influx of extracellular calcium. RSM can also inhibit KCl-induced influx of calcium, indicating its characteristic of blocking voltage-operated Ca2+ channel.
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22
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Sarem M, Znaidak R, Macías M, Rey R. [Hepatic stellate cells: it's role in normal and pathological conditions]. GASTROENTEROLOGIA Y HEPATOLOGIA 2006; 29:93-101. [PMID: 16448612 DOI: 10.1157/13083906] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hepatic fibrosis is a dynamic and sophisticatedly regulated wound healing response to chronic hepatocellular injury. This fibrotic process results from the accumulation of extracellular matrix (ECM) including collagen, proteoglycan, and adhesive glycoproteins which are principally produced by hepatic stellate cells (HSC), a mesenchymal cell type located between parenchymal cell plates and sinusoidal endothelial cells in the space of Disse. In physiological conditions, quiescent HSCs play important roles in the regulation of retinoid homeostasis and ECM remodeling by producing ECM components as well as metalloproteases and its inhibitor. However during hepatic fibrogenesis, HSCs are known to be activated or "transdifferentiated" to myofibroblast-like cells which play a pivotal role in ECM remodeling and hepatic blood flow regulation. Activation of HSC is now well established as the key process involved in the development of hepatic fibrosis. Both basic morphology and functions of HSCs in normal conditions and its role in pathological fibrosis will be discussed in this review.
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Affiliation(s)
- M Sarem
- Facultad de Medicina, Instituto Universitario de Ciencias de la Salud, Fundación H.A. Barceló, Buenos Aires, Argentina.
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23
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Sancho-Bru P, Bataller R, Gasull X, Colmenero J, Khurdayan V, Gual A, Nicolás JM, Arroyo V, Ginès P. Genomic and functional characterization of stellate cells isolated from human cirrhotic livers. J Hepatol 2005; 43:272-82. [PMID: 15964095 DOI: 10.1016/j.jhep.2005.02.035] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 01/17/2005] [Accepted: 02/23/2005] [Indexed: 02/06/2023]
Abstract
BACKGROUND/AIMS Hepatic stellate cells (HSCs) are believed to participate in liver fibrogenesis and portal hypertension. Knowledge on human HSCs is based on studies using HSCs isolated from normal livers. We investigated the phenotypic, genomic and functional characteristics of HSCs from human cirrhotic livers. METHODS HSC were obtained from normal and cirrhotic human livers. Cells were characterized by immunocytochemistry and gene microarray analysis. Cell proliferation, Ca(2+) changes and cell contraction were assessed by 3H-thymidine incorporation and by using an epifluorescence microscope. RESULTS HSCs freshly isolated from human cirrhotic livers showed phenotypical features of myofibroblasts. These features were absent in HSCs freshly isolated from normal human livers and become prominent after prolonged culture. HSCs from cirrhotic human livers markedly express genes involved in fibrogensis, inflammation and apoptosis. HSCs from normal livers after prolonged culture preferntially expressed genes related to fibrogenesis and contractility. Agonists induced proliferation, Ca(2+) increase and cell contraction in HSCs isolated from human cirrhotic livers. Response to agonists was more marked in culture-activated HSCs and was not observed in HSCs freshly isolated from normal livers. CONCLUSIONS HSCs from human cirrhotic livers show fibrogenic and contractile features. However, the current model of HSCs activated in culture does not exactly reproduce the activated phenotype found in cirrhotic human livers.
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Affiliation(s)
- Pau Sancho-Bru
- Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Catalonia, Spain
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Chilton L, Ohya S, Freed D, George E, Drobic V, Shibukawa Y, Maccannell KA, Imaizumi Y, Clark RB, Dixon IMC, Giles WR. K+ currents regulate the resting membrane potential, proliferation, and contractile responses in ventricular fibroblasts and myofibroblasts. Am J Physiol Heart Circ Physiol 2005; 288:H2931-9. [PMID: 15653752 DOI: 10.1152/ajpheart.01220.2004] [Citation(s) in RCA: 156] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite the important roles played by ventricular fibroblasts and myofibroblasts in the formation and maintenance of the extracellular matrix, neither the ionic basis for membrane potential nor the effect of modulating membrane potential on function has been analyzed in detail. In this study, whole cell patch-clamp experiments were done using ventricular fibroblasts and myofibroblasts. Time- and voltage-dependent outward K+ currents were recorded at depolarized potentials, and an inwardly rectifying K+ (Kir) current was recorded near the resting membrane potential (RMP) and at more hyperpolarized potentials. The apparent reversal potential of Kir currents shifted to more positive potentials as the external K+ concentration ([K+]o) was raised, and this Kir current was blocked by 100–300 μM Ba2+. RT-PCR measurements showed that mRNA for Kir2.1 was expressed. Accordingly, we conclude that Kir current is a primary determinant of RMP in both fibroblasts and myofibroblasts. Changes in [K+]o influenced fibroblast membrane potential as well as proliferation and contractile functions. Recordings made with a voltage-sensitive dye, DiBAC3(4), showed that 1.5 mM [K+]o resulted in a hyperpolarization, whereas 20 mM [K+]o produced a depolarization. Low [K+]o (1.5 mM) enhanced myofibroblast number relative to control (5.4 mM [K+]o). In contrast, 20 mM [K+]o resulted in a significant reduction in myofibroblast number. In separate assays, 20 mM [K+]o significantly enhanced contraction of collagen I gels seeded with myofibroblasts compared with control mechanical activity in 5.4 mM [K+]o. In combination, these results show that ventricular fibroblasts and myofibroblasts express a variety of K+ channel α-subunits and demonstrate that Kir current can modulate RMP and alter essential physiological functions.
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Affiliation(s)
- L Chilton
- Dept. of Bioengineering, Univ. of California-San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0412, USA
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25
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Kharbanda KK, Rogers DD, Wyatt TA, Sorrell MF, Tuma DJ. Transforming growth factor-beta induces contraction of activated hepatic stellate cells. J Hepatol 2004; 41:60-6. [PMID: 15246209 DOI: 10.1016/j.jhep.2004.03.019] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2003] [Revised: 03/29/2004] [Accepted: 03/31/2004] [Indexed: 12/23/2022]
Abstract
BACKGROUND/AIMS Transforming growth factor-beta (TGF-beta) is a cytokine produced in abundance during liver injury. Recognizing the prominent roles that hepatic stellate cells (HSCs) and TGF-beta play in portal hypertension and fibrogenesis, respectively, we sought to evaluate the effect of TGF-beta on the contractility of activated HSCs. METHODS Spontaneous immortalized cell lines of HSC origin were used in this study. Cells were grown in three-dimensional collagen gel lattice, transferred to 60 mm dishes and exposed to varying concentrations of TGF-beta1 in serum-free medium at 37 degrees C for up to 120 h. The area of the floating gels was measured using a Fluor S-MultiImager (Biorad), the cellular smooth muscle-alpha actin (SMA) content quantified and PKC activation studies conducted. RESULTS TGF-beta1 induced a time- and dose-dependent decrease in lattice area up to 40% of control (P<0.05) that reflects the contraction of activated HSCs. This induced contraction was associated with increases in SMA content (3-fold, P<0.05) and PKC activation (5-fold, P<0.05) in these cells. Furthermore, pre-incubating with a PKC--specific inhibitor completely abrogated the TGF-beta-induced contraction. CONCLUSIONS TGF-beta induces contraction of activated HSCs via an increase in SMA content and a PKC--mediated pathway.
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Affiliation(s)
- Kusum K Kharbanda
- Department of Veterans Affairs Medical Center, VA Alcohol Research Center, 4101 Woolworth Avenue, Omaha, NE 68105, USA.
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26
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Schwabe RF, Bataller R, Brenner DA. Human hepatic stellate cells express CCR5 and RANTES to induce proliferation and migration. Am J Physiol Gastrointest Liver Physiol 2003; 285:G949-58. [PMID: 12829440 DOI: 10.1152/ajpgi.00215.2003] [Citation(s) in RCA: 193] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Activated hepatic stellate cells (HSCs) are the main producers of extracellular matrix in the fibrotic liver and are involved in the regulation of hepatic inflammation. The aim of this study was to characterize the role of regulated on activation, normal T-cell expressed, and presumably secreted (RANTES) in activated HSCs. RANTES mRNA and protein secretion were strongly induced after stimulating HSCs with TNF-alpha, IL-1beta, or CD40L. RANTES production was NF-kappaB dependent, because inhibitor-kappaB (IkappaB) superrepressor and dominant-negative IkappaB kinase-2 almost completely blocked RANTES expression. NF-kappaB activation was sufficient to drive RANTES expression as demonstrated by the strong induction of RANTES in HSCs expressing NF-kappaB-inducing kinase. The JNK/activator protein-1 pathway also contributed to RANTES expression as demonstrated by the blocking effects of the JNK inhibitor SP600125. HSCs responded to stimulation with recombinant human (rh)RANTES with an increase in intracellular calcium concentration and a rapid increase in free radical formation. Furthermore, rhRANTES induced ERK phosphorylation, ERK-dependent [3H]thymidine incorporation, and HSC proliferation. Additionally, rhRANTES induced focal adhesion kinase phosphorylation and a substantial increase in HSC migration. HSCs functionally expressed chemokine receptor-5 (CCR5), as shown by flow-cytometric analysis and RT-PCR, and the inhibitory effects of a blocking CCR5 antibody on rhRANTES-induced ERK activation, proliferation, and migration. Diphenylene iodonium and N-acetylcysteine inhibited rhRANTES-induced ERK activation and HSC proliferation, indicating that NADPH oxidase-dependent production of reactive oxygen species was required. In conclusion, RANTES and CCR5 represent potential mediators of 1) HSC migration and proliferation and 2) a cross-talk between HSCs and leukocytes during fibrogenesis.
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Affiliation(s)
- Robert F Schwabe
- Columbia University College of Physicians and Surgeons, 630 West 168th St., PH8East, Rm. 105J, New York, NY 10032-3784, USA
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N/A. N/A. Shijie Huaren Xiaohua Zazhi 2003; 11:334-337. [DOI: 10.11569/wcjd.v11.i3.334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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28
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Gasull X, Bataller R, Ginès P, Sancho-Bru P, Nicolás JM, Görbig MN, Ferrer E, Badía E, Gual A, Arroyo V, Rodés J. Human myofibroblastic hepatic stellate cells express Ca(2+)-activated K(+) channels that modulate the effects of endothelin-1 and nitric oxide. J Hepatol 2001; 35:739-48. [PMID: 11738101 DOI: 10.1016/s0168-8278(01)00198-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND/AIMS High-conductance Ca(2+)-activated K(+) (BK(Ca)) channels modulate the effects of vasoactive factors in contractile cells. It is unknown whether hepatic stellate cells (HSCs) contain BK(Ca) channels and what their role in the regulation of HSCs contractility is. METHODS The presence of BK(Ca) channels in HSCs was assessed by the patch-clamp technique. The functional role of BK(Ca) channels was investigated by measuring intracellular calcium concentration ([Ca(2+)](i)) and cell contraction in individual cells after stimulation with endothelin-1 in the presence or absence of specific modulators of BK(Ca) channels. RESULTS BK(Ca) channels were detected by patch-clamp in most of the activated HSCs studied. Incubation of cells with iberiotoxin, a BK(Ca) channel blocker, increased both the sustained phase of [Ca(2+)](i) elicited by endothelin-1 and the number of cells undergoing contraction, while the use of NS1619, a BK(Ca) channel opener, induced opposite effects. Stimulation of HSCs with S-nitroso-N-acetyl-penicillamine (SNAP), a nitric oxide (NO)-donor, increased the opening of BK(Ca) channels and reduced the effects of endothelin-1. Conversely, iberiotoxin abolished the inhibitory effect of SNAP on endothelin-induced [Ca(2+)](i) increase and cell contraction. CONCLUSIONS Activated human HSCs contain BK(Ca) channels that modulate the contractile effect of endothelin-1 and mediate the inhibitory action of NO.
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Affiliation(s)
- X Gasull
- Laboratory of Neurophysiology, University of Barcelona School of Medicine, IDIBAPS, Catalonia, Barcelona, Spain
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Murata T, Arii S, Nakamura T, Mori A, Kaido T, Furuyama H, Furumoto K, Nakao T, Isobe N, Imamura M. Inhibitory effect of Y-27632, a ROCK inhibitor, on progression of rat liver fibrosis in association with inactivation of hepatic stellate cells. J Hepatol 2001; 35:474-81. [PMID: 11682031 DOI: 10.1016/s0168-8278(01)00169-6] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND/AIMS Activation of hepatic stellate cells (HSCs) is a final common pathway of liver fibrosis. Recently, it has been demonstrated that the small GTPase Rho is involved in HSCs activation, and that Y-27632, an inhibitor of Rho-kinase which is an effector that acts downstream of Rho, inhibits Rho-associated effects. The objective of the current study was to investigate the inhibitory effects of Y-27632 on the activation of HSCs and the progression of liver fibrosis. METHODS Y-27632 (1, 10, 100 microM) was added to HSCs isolated from normal rat liver. RESULTS HSCs maintained the 'star-like' configuration of the quiescent stage in the presence of Y-27632, as well as inhibition of the expression of Na+/Ca2+ exchanger mRNA which was reported to be an indicator of HSCs activation. In addition, when Y-27632 (30 mg/kg body weight) was administered to rats with carbon tetrachloride-induced liver fibrosis, collagen deposition was inhibited, the hepatic hydroxyproline content was decreased, and the serum hyaluronic acid level was reduced. Moreover, Y-27632 reduced the number of smooth muscle alpha-actin-positive cells and transforming growth factor-beta1-positive cells, and inhibited the expression of Na/Ca2+ exchanger mRNA. CONCLUSIONS These findings indicate that Y-27632 may be useful for the clinical management of liver fibrosis.
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Affiliation(s)
- T Murata
- Department of Surgery and Surgical Basic Science, Graduate School of Medicine, Kyoto University, Japan.
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Görbig MN, Ginès P, Bataller R, Nicolás JM, Garcia-Ramallo E, Cejudo P, Sancho-Bru P, Jiménez W, Arroyo V, Rodés J. Human hepatic stellate cells secrete adrenomedullin: potential autocrine factor in the regulation of cell contractility. J Hepatol 2001; 34:222-9. [PMID: 11281550 DOI: 10.1016/s0168-8278(00)00016-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND/AIMS Hepatic stellate cells (HSCs) are perisinusoidal pericytes which have receptors for vasoactive factors, such as endothelin-1, which can regulate cell contractility in an autocrine manner. It is unknown whether human HSCs have receptors for and are able to synthesize the vasodilator peptide adrenomedullin (ADM), a peptide produced by most contractile cells. METHODS AND RESULTS Stimulation of HSCs with ADM resulted in a dose-dependent raise in cAMP concentration (radioimmunoassay) and markedly blunted the endothelin-induced increase in [Ca2+]i and cell contraction, as assessed in cells loaded with fura-2 using a morphometric method. The existence of the receptor CRLR for ADM and their associated proteins RAMP-1 and RAMP-2 was demonstrated by reverse transcriptase-polymerase chain reaction (RT-PCR). Moreover, activated human HSCs spontaneously secreted ADM in the culture medium in a time-dependent manner. ADM secretion was markedly enhanced by tumour necrosis factor-alpha and interleukin-1beta. Specific mRNA for ADM (RT-PCR and Northern blot) was detected in HSCs and increased after incubation of cells with cytokines. CONCLUSIONS Human HSCs have functional receptors for ADM, the stimulation of which blunts the contractile effect of endothelin-1. Cultured human HSCs secrete ADM in baseline conditions. This secretion is markedly increased by cytokines. These results suggest that ADM can regulate HSCs' contractility in an autocrine manner.
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Affiliation(s)
- M N Görbig
- Institute of Digestive Diseases, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi-Sunyer, University of Barcelona School of Medicine, Catalonia, Spain
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Titos E, Clària J, Bataller R, Bosch-Marcé M, Ginès P, Jiménez W, Arroyo V, Rivera F, Rodés J. Hepatocyte-derived cysteinyl leukotrienes modulate vascular tone in experimental cirrhosis. Gastroenterology 2000; 119:794-805. [PMID: 10982774 DOI: 10.1053/gast.2000.17831] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS The leukotrienes C(4)/D(4)/E(4) (cysteinyl-LTs) are 5-lipoxygenase (5-LO)-derived eicosanoids with potent vasoconstrictor, proliferative, and profibrogenic properties that may participate in key pathophysiologic events in liver cirrhosis. We examined the cysteinyl-LT biosynthetic pathway in liver tissue and purified liver cells isolated from rats with carbon tetrachloride-induced cirrhosis, and assessed the vasoactive properties of LTD(4) in hepatic stellate cells (HSCs) and anesthetized rats. METHODS & RESULTS Liver homogenates from cirrhotic rats had increased 5-LO mRNA and cysteinyl-LT content, as determined by Northern blot and enzyme immunoassay, respectively. In isolated rat liver cells, 5-LO mRNA expression was found to be restricted to Kupffer cells. However, among the liver cells (i.e., hepatocytes, Kupffer cells, HSCs, and sinusoidal endothelial cells), hepatocytes exhibited the highest ability to generate cysteinyl-LTs from the unstable intermediate LTA(4). Hepatocytes from cirrhotic rats showed an enhanced baseline generation of cysteinyl-LTs, but their ability to synthesize cysteinyl-LTs from exogenous LTA(4) was found to be similar to that of hepatocytes from normal animals. Both LTD(4) and hepatocyte-conditioned medium increased intracellular Ca(2+) concentration and induced contraction in HSCs, suggesting that hepatocyte-derived cysteinyl-LTs could act in a paracrine fashion on nearby nonparenchymal liver cells. The relevance of these in vitro findings was further established in vivo by the observation that LTD(4) significantly increased portal pressure in anesthetized rats. CONCLUSIONS These data suggest a role for hepatocyte-derived cysteinyl-LTs in mediating hepatic vascular tone abnormalities in cirrhosis.
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Affiliation(s)
- E Titos
- DNA Unit, Institut d'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
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Abstract
Knowledge on the development and progression of liver fibrosis has grown exponentially in the past decade. At present, liver fibrogenesis is referred to as a dynamic process involving complex cellular and molecular mechanisms, resulting from the chronic activation of the tissue repair mechanisms that follows reiterated liver tissue injury. The identification and characterization of the cell types and of the different mediators involved in this process has allowed a "re-visitation" of several issues related to liver cirrhosis and its immediate consequences. Among these, evaluation of the relationships occurring between fibrogenesis and portal hypertension, cholestasis and the development of hepatocellular carcinoma, represent some of the hottest areas of research in this field of hepatology. The elucidation of many of the cellular and molecular mechanisms responsible for the progression of liver fibrosis has provided a sound basis for the development of pharmacological strategies able to modulate this important pathophysiological process.
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Bataller R, Ginès P, Nicolás JM, Görbig MN, Garcia-Ramallo E, Gasull X, Bosch J, Arroyo V, Rodés J. Angiotensin II induces contraction and proliferation of human hepatic stellate cells. Gastroenterology 2000; 118:1149-56. [PMID: 10833490 DOI: 10.1016/s0016-5085(00)70368-4] [Citation(s) in RCA: 342] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND & AIMS Circulating levels of angiotensin II (ANGII), a powerful vasoconstrictor factor, are frequently increased in chronic liver diseases. In these conditions, hepatic stellate cells (HSCs) proliferate and acquire contractile properties. This study investigated the presence of receptors for ANGII and the effects of ANGII in human HSCs activated in culture. METHODS The presence of ANGII receptors was assessed by binding studies. The effects of ANGII on intracellular calcium concentration ([Ca(2+)](i)), cell contraction, and cell proliferation were also assessed. RESULTS Binding studies showed the presence of ANGII receptors of the AT1 subtype. ANGII elicited a marked dose-dependent increase in [Ca(2+)](i) and cell contraction. Moreover, ANGII stimulated DNA synthesis and increased cell number. All these effects were totally blocked by losartan and reduced by nitric oxide donors or prostaglandin E(2). The effects of ANGII were barely detectable in quiescent cells (2 days in culture), suggesting that phenotypic transformation of HSCs is associated with a marked increase in the effects of ANGII. CONCLUSIONS ANGII induces contraction and is mitogenic for human-activated HSCs by acting through AT1 receptors. These results suggest that activated HSCs are targets of the vasoconstrictor action of ANGII in the intrahepatic circulation.
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Görbig MN, Ginès P, Bataller R, Nicolás JM, Garcia-Ramallo E, Tobías E, Titos E, Rey MJ, Clària J, Arroyo V, Rodés J. Atrial natriuretic peptide antagonizes endothelin-induced calcium increase and cell contraction in cultured human hepatic stellate cells. Hepatology 1999; 30:501-9. [PMID: 10421660 DOI: 10.1002/hep.510300201] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Hepatic stellate cells (HSCs) participate in the regulation of hepatic microcirculation and have receptors for many vasoconstrictor factors. It is unknown whether HSCs have receptors for circulating vasodilators such as atrial natriuretic peptide (ANP). This study investigated the presence of ANP receptors in human HSCs and whether ANP antagonizes the effects of endothelin-1 in these cells. ANP receptors were assessed by binding and cross-linking studies, reverse-transcriptase polymerase chain reaction (PCR), and measuring intracellular cyclic guanosine monophosphate concentration. Intracellular calcium concentration ([Ca(2+)](i)) and cell contraction were measured in individual cells loaded with fura-2 using a morphometric method. Binding and cross-linking affinity experiments showed the existence of ANP receptors in human HSCs. PCR products with the expected length were obtained for guanylate cyclase A receptor, the physiological receptor of ANP, both in quiescent and activated human cells. ANP induced a dose-dependent increase in intracellular cyclic guanosine monophosphate concentration and blunted the increase in [Ca(2+)](i) elicited by endothelin-1. Most importantly, ANP markedly reduced cell contraction induced by endothelin-1. HSCs isolated from rats with carbon tetrachloride-induced cirrhosis showed a higher number of ANP receptors compared with HSCs isolated from normal rats, indicating that in vivo activation of HSCs is associated with an up-regulation of ANP receptors. These results indicate that human HSCs have receptors for ANP, the activation of which reduces the effects of endothelin-1 on [Ca(2+)](i) and cell contraction. ANP could participate in regulating the contractility of HSCs by antagonizing the effect of vasoconstrictors.
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Affiliation(s)
- M N Görbig
- Liver Unit,Department of Pathology, Hospital Clinic, Villarroel Barcelona, Spain
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Roth-Eichhorn S, Eberheim A, Bode HP, Gressner AM. Transformation-dependent calcium influx by voltage-operated calcium channels in stellate cells of rat liver. J Hepatol 1999; 30:612-20. [PMID: 10207802 DOI: 10.1016/s0168-8278(99)80191-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS The transformation of hepatic stellate cells into myofibroblasts is a key step in the pathogenesis of fibrotic liver diseases. The intracellular signaling associated with hepatic stellate cell transformation becomes a point of interest, especially the role of cytosolic free calcium concentration ([Ca2+]i). The aim of the study was to investigate possible differences between various transformation phenotypes of hepatic stellate cells with regard to the calcium influx mediated by L-type voltage-operated calcium channels (L-type VOC). METHODS Hepatic stellate cells were isolated from rat liver by pronase-collagenase reperfusion and cultured under standard conditions. The transformation of hepatic stellate cells was stimulated by treatment with transforming growth factor-beta (TGF-beta) or inhibited with interferon-gamma (IFN-gamma) and characterized by immunocytochemistry for smooth muscle alpha-actin and determination of hyaluronan in the culture media with a ligand binding assay. [Ca2+]i was measured in individual cells with fluorescence microscopy using fura-2. VOCs were activated by the standard procedure of extracellular potassium elevation, to achieve depolarization, and identified by various controls. RESULTS In transformed myofibroblasts the activation of VOCs by potassium elevation from 5.4 mmol/l to 50.4 mmol/l led to a 19% increase in [Ca2+]i in contrast to 0.2% in hepatic stellate cells cultured for 3 days. In 7-day old hepatic stellate cells, after stimulation of cell transformation with TGF-beta-1, an enhanced [Ca2+]i response to potassium elevation was detected, while inhibition of transformation with IFN-gamma for the same time caused a decreased calcium signal compared with untreated control cultures. Short-term treatment with the cytokines (1 day) did not influence depolarization-dependent calcium signals. CONCLUSION The results show the [Ca2+]i increase via L-type VOCs to be dependent on the transformation level of hepatic stellate cells into myofibroblasts which can be influenced by the long-term treatment of hepatic stellate cells with TGF-beta or IFN-gamma. In contrast, there is no evidence for direct regulation of VOC activity by TGF-beta or IFN-gamma after short-term exposure.
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Affiliation(s)
- S Roth-Eichhorn
- Department of Clinical Chemistry, Philipps University, Marburg, Germany.
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36
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Abstract
Knowledge on the development and progression of liver fibrosis has grown exponentially in the past decade. At present, liver fibrogenesis is referred to as a dynamic process involving complex cellular and molecular mechanisms, resulting from the chronic activation of the tissue repair mechanisms that follows reiterated liver tissue injury. The identification and characterization of the cell types and of the different mediators involved in this process has allowed a "re-visitation" of several issues related to liver cirrhosis and its immediate consequences. Among these, evaluation of the relationships occurring between fibrogenesis and portal hypertension, cholestasis and the development of hepatocellular carcinoma, represent some of the hottest areas of research in this field of hepatology. The elucidation of many of the cellular and molecular mechanisms responsible for the progression of liver fibrosis has provided a sound basis for the development of pharmacological strategies able to modulate this important pathophysiological process.
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Affiliation(s)
- M Pinzani
- Dipartimento di Medicina Interna, Università degli Studi di Firenze, Italy
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