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Casas-Grajales S, Reyes-Gordillo K, Cerda-García-Rojas CM, Tsutsumi V, Lakshman MR, Muriel P. Rebaudioside A administration prevents experimental liver fibrosis: an in vivo and in vitro study of the mechanisms of action involved. J Appl Toxicol 2019; 39:1118-1131. [PMID: 30883860 DOI: 10.1002/jat.3797] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/15/2019] [Accepted: 02/15/2019] [Indexed: 12/18/2022]
Abstract
Rebaudioside A (Reb A) is a diterpenoid isolated from the leaves of Stevia rebaudiana (Bertoni) that has been shown to possess pharmacological activity, including anti-inflammatory and antioxidant properties. However, the ability of Reb A to prevent liver injury has not been evaluated. Therefore, we aimed to study the potential of Reb A (20 mg/kg; two times daily intraperitoneally) to prevent liver injury induced by thioacetamide (TAA) administration (200 mg/kg; three times per week intraperitoneally). In addition, cocultures were incubated with either lipopolysaccharide or ethanol. Antifibrotic, antioxidant and immunological responses were evaluated. Chronic TAA administration produced considerable liver damage and distorted the liver parenchyma with the presence of prominent thick bands of collagen. In addition, TAA upregulated the expression of α-smooth muscle actin, transforming growth factor-β1, metalloproteinases 9, 2 and 13, and nuclear factor kappaB and downregulated nuclear erythroid factor 2. Reb A administration prevented all of these changes. In cocultured cells, Reb A prevented the upregulation of genes implicated in fibrotic and inflammatory processes when cells were exposed to ethanol and lipopolysaccharide. Altogether, our results suggest that Reb A prevents liver damage by blocking oxidative processes via upregulation of nuclear erythroid factor 2, exerts immunomodulatory effects by downregulating the nuclear factor-κB system and acts as an antifibrotic agent by maintaining collagen content.
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Affiliation(s)
- Sael Casas-Grajales
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Karina Reyes-Gordillo
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Science, The George Washington University Medical Center, 2300 I St. NW, Washington, DC, 20052, USA.,Lipid Research Laboratory, VA Medical Center, 50 Irving St., Washington, DC, 20422, USA
| | - Carlos M Cerda-García-Rojas
- Department of Chemistry, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Víctor Tsutsumi
- Department of Infectomics and Molecular Pathogenesis, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - M Raj Lakshman
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Science, The George Washington University Medical Center, 2300 I St. NW, Washington, DC, 20052, USA.,Lipid Research Laboratory, VA Medical Center, 50 Irving St., Washington, DC, 20422, USA
| | - Pablo Muriel
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
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Casas-Grajales S, Ramos-Tovar E, Chávez-Estrada E, Alvarez-Suarez D, Hernández-Aquino E, Reyes-Gordillo K, Cerda-García-Rojas CM, Camacho J, Tsutsumi V, Lakshman MR, Muriel P. Antioxidant and immunomodulatory activity induced by stevioside in liver damage: In vivo, in vitro and in silico assays. Life Sci 2019; 224:187-196. [PMID: 30890404 DOI: 10.1016/j.lfs.2019.03.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/13/2019] [Accepted: 03/15/2019] [Indexed: 01/16/2023]
Abstract
AIMS Stevioside is a diterpenoid obtained from the leaves of Stevia rebaudiana (Bertoni) that exhibits antioxidant, antifibrotic, antiglycemic and anticancer properties. Therefore, we aimed to study whether stevioside has beneficial effects in liver injury induced by long-term thioacetamide (TAA) administration and investigated the possible underlying molecular mechanism using in vivo, in vitro and in silico approaches. MAIN METHODS Liver injury was induced in male Wistar rats by TAA administration (200 mg/kg), intraperitoneally, three times per week. Rats received saline or stevioside (20 mg/kg) twice daily intraperitoneally. In addition, cocultures were incubated with either lipopolysaccharide or ethanol. Liver injury, antioxidant and immunological responses were evaluated. KEY FINDINGS Chronic TAA administration induced significant liver damage. In addition, TAA upregulated the protein expression of nuclear factor (NF)-κB, thus increasing the expression of proinflammatory cytokines and decreasing the antioxidant capacity of the liver through downregulation of nuclear erythroid factor 2 (Nrf2). Notably, stevioside administration prevented all of these changes. In vitro, stevioside prevented the upregulation of several genes implicated in liver inflammation when cocultured cells were incubated with lipopolysaccharide or ethanol. In silico assays using tumor necrosis factor receptor (TNFR)-1 and Toll-like receptor (TLR)-4-MD2 demonstrated that stevioside docks with TNFR1 and TLR4-MD2, thus promoting an antagonistic action against this proinflammatory mediator. SIGNIFICANCE Collectively, these data suggest that stevioside prevented liver damage through antioxidant activity by upregulating Nrf2 and immunomodulatory activity by blocking NF-κB signaling.
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Affiliation(s)
- Sael Casas-Grajales
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Erika Ramos-Tovar
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Esmeralda Chávez-Estrada
- Department of Chemistry, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Diana Alvarez-Suarez
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Erika Hernández-Aquino
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Karina Reyes-Gordillo
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Science, The George Washington University Medical Center, 2300 I St NW, Washington, DC 20052, United States of America; Lipid Research Laboratory, VA Medical Center, 50 Irving St, Washington, DC 20422, United States of America
| | - Carlos M Cerda-García-Rojas
- Department of Chemistry, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Javier Camacho
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - Víctor Tsutsumi
- Department of Infectomics and Molecular Pathogenesis, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico
| | - M Raj Lakshman
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Science, The George Washington University Medical Center, 2300 I St NW, Washington, DC 20052, United States of America; Lipid Research Laboratory, VA Medical Center, 50 Irving St, Washington, DC 20422, United States of America
| | - Pablo Muriel
- Department of Pharmacology, Cinvestav-IPN, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, 07360, Apartado Postal 14-740, Mexico City, Mexico.
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Casas-Grajales S, Alvarez-Suarez D, Ramos-Tovar E, Dayana Buendía-Montaño L, Reyes-Gordillo K, Camacho J, Tsutsumi V, Lakshman MR, Muriel P. Stevioside inhibits experimental fibrosis by down-regulating profibrotic Smad pathways and blocking hepatic stellate cell activation. Basic Clin Pharmacol Toxicol 2019; 124:670-680. [PMID: 30561898 DOI: 10.1111/bcpt.13194] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Accepted: 12/10/2018] [Indexed: 12/20/2022]
Abstract
Liver cirrhosis is associated with increased morbidity and mortality with important health and social consequences; however, an effective treatment has not been found yet. Previous reports have shown some beneficial effects of stevioside (SVT) in different diseases, but the ability of SVT to inhibit liver cirrhosis has not been reported. Therefore, we studied the potential of this diterpenoid to inhibit liver cirrhosis induced by thioacetamide, a model that shares many similarities with the human disease, and investigated the possible underlying molecular mechanism using in vivo and in vitro approaches. Cirrhosis was induced in male Wistar rats by chronic thioacetamide administration (200 mg/kg) intraperitoneally three times per week. Rats received saline or SVT (20 mg/kg) two times daily intraperitoneally. In addition, co-cultures were incubated with either lipopolysaccharide or ethanol. Liver fibrosis, hepatic stellate cells activation, metalloproteinases activity, canonical and non-canonical Smads pathway and expression of several profibrogenic genes were evaluated. Thioacetamide activated hepatic stellate cells and distorted the liver parenchyma with the presence of abundant thick bands of collagen. In addition, thioacetamide up-regulated the protein expression of α-smooth muscle actin, transforming growth factor-β1, metalloproteinases-9,-2 and -13 and overstimulate the canonical and non-canonical Smad pathways. SVT administration inhibited all of these changes. In vitro, SVT inhibited the up-regulation of several genes implicated in cirrhosis when cells were exposed to lipopolysaccharides or ethanol. We conclude that SVT inhibited liver damage by blocking hepatic stellate cells activation, down-regulating canonical and non-canonical profibrotic Smad pathways.
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Affiliation(s)
| | | | | | | | - Karina Reyes-Gordillo
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Science, The George Washington University Medical Center, Washington, District of Columbia.,Lipid Research Laboratory, VA Medical Center, Washington, District of Columbia
| | - Javier Camacho
- Department of Pharmacology, Cinvestav-IPN, Mexico City, Mexico
| | - Víctor Tsutsumi
- Department of Infectomics and Molecular Pathogenesis, Cinvestav-IPN, Mexico City, Mexico
| | - M Raj Lakshman
- Department of Biochemistry and Molecular Biology, School of Medicine and Health Science, The George Washington University Medical Center, Washington, District of Columbia.,Lipid Research Laboratory, VA Medical Center, Washington, District of Columbia
| | - Pablo Muriel
- Department of Pharmacology, Cinvestav-IPN, Mexico City, Mexico
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Abstract
Hepatic stellate cells (HSCs) are found in the perisinusoidal space of the liver (i.e., the space of Dissé). They represent 5-8% of the total number of liver cells. In normal liver, these cells have a quiescent phenotype and are characterized by numerous fat vacuoles that store vitamin A in a form of retinyl ester. In injured liver, these cells transdifferentiate into a myofibroblast phenotype, become highly proliferative and are responsible for excess collagen synthesis and deposition during fibrosis. Due to their exceptional pathophysiological relevance, several isolation and purification protocols of primary HSCs have been established that provide the basis for studying HSC biology in vitro. We here describe a method for high-purity isolation of HSCs from mice. This protocol includes the enzymatic digestion of the liver tissue by pronase and collagenase, cellular enrichment by centrifugation of the crude cell suspension through a Nycodenz density gradient, and a final (optional) flow cytometric enrichment that allows generating ultrapure HSC fractions.
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Zeilinger K, Freyer N, Damm G, Seehofer D, Knöspel F. Cell sources for in vitro human liver cell culture models. Exp Biol Med (Maywood) 2016; 241:1684-98. [PMID: 27385595 PMCID: PMC4999620 DOI: 10.1177/1535370216657448] [Citation(s) in RCA: 139] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In vitro liver cell culture models are gaining increasing importance in pharmacological and toxicological research. The source of cells used is critical for the relevance and the predictive value of such models. Primary human hepatocytes (PHH) are currently considered to be the gold standard for hepatic in vitro culture models, since they directly reflect the specific metabolism and functionality of the human liver; however, the scarcity and difficult logistics of PHH have driven researchers to explore alternative cell sources, including liver cell lines and pluripotent stem cells. Liver cell lines generated from hepatomas or by genetic manipulation are widely used due to their good availability, but they are generally altered in certain metabolic functions. For the past few years, adult and pluripotent stem cells have been attracting increasing attention, due their ability to proliferate and to differentiate into hepatocyte-like cells in vitro However, controlling the differentiation of these cells is still a challenge. This review gives an overview of the major human cell sources under investigation for in vitro liver cell culture models, including primary human liver cells, liver cell lines, and stem cells. The promises and challenges of different cell types are discussed with a focus on the complex 2D and 3D culture approaches under investigation for improving liver cell functionality in vitro Finally, the specific application options of individual cell sources in pharmacological research or disease modeling are described.
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Affiliation(s)
- Katrin Zeilinger
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Nora Freyer
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Georg Damm
- Department of General-, Visceral- and Transplantation Surgery, Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Daniel Seehofer
- Department of General-, Visceral- and Transplantation Surgery, Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Fanny Knöspel
- Berlin-Brandenburg Center for Regenerative Therapies (BCRT), Charité - Universitätsmedizin Berlin, 13353 Berlin, Germany
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Regulation of matrix metalloproteinase-1 and alpha-smooth muscle actin expression by interleukin-1 alpha and tumour necrosis factor alpha in hepatic stellate cells. Cytotechnology 2016; 69:461-468. [PMID: 26825680 DOI: 10.1007/s10616-016-9948-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 01/17/2016] [Indexed: 01/17/2023] Open
Abstract
Hepatic stellate cells (HSCs) are key players in liver fibrosis and regeneration via collagen degradation and synthesis. These phenomena involve inflammatory cytokines released from non-parenchymal liver cells such as Kupffer cells. Although the effects of individual cytokines on many cell types have been investigated in various conditions, such as inflammation and tissue fibrosis, investigating the effect of combined cytokines would further our understanding of the regulatory mechanisms in tissue fibrosis. Here, we report the effect of multiple cytokine combinations on primary HSCs. We first examined the effect of individual cytokines and then the simultaneous exposure of different cytokines, including interleukin-6 (IL-6), IL-1 alpha (IL-1α), platelet-derived growth factor (PDGF), tumour necrosis factor-alpha (TNF-α) and transforming growth factor-beta (TGF-β), on matrix metalloproteinase-1 (MMP1) gene expression in primary HSCs. We observed that the combination of all five cytokines induced higher levels of MMP1 gene expression. Of these cytokines, TNF-α and IL-1α were found to be the key cytokines for not only inducing MMP1 expression, but also increasing α-smooth muscle actin gene expression. In conclusion, the combined treatment of TNF-α and IL-1α on HSCs had an enhanced effect on the expression of the fibrotic genes, MMP1 and α-smooth muscle actin, so appears to be an important regulator for tissue regeneration. This finding suggests that stimulation with combined anti-fibrotic cytokines is a potential approach in the development of a novel therapy for the recovery of liver fibrosis.
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All-In-One: Advanced preparation of Human Parenchymal and Non-Parenchymal Liver Cells. PLoS One 2015; 10:e0138655. [PMID: 26407160 PMCID: PMC4583235 DOI: 10.1371/journal.pone.0138655] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 09/02/2015] [Indexed: 02/06/2023] Open
Abstract
Background & Aims Liver cells are key players in innate immunity. Thus, studying primary isolated liver cells is necessary for determining their role in liver physiology and pathophysiology. In particular, the quantity and quality of isolated cells are crucial to their function. Our aim was to isolate a large quantity of high-quality human parenchymal and non-parenchymal cells from a single liver specimen. Methods Hepatocytes, Kupffer cells, liver sinusoidal endothelial cells, and stellate cells were isolated from liver tissues by collagenase perfusion in combination with low-speed centrifugation, density gradient centrifugation, and magnetic-activated cell sorting. The purity and functionality of cultured cell populations were controlled by determining their morphology, discriminative cell marker expression, and functional activity. Results Cell preparation yielded the following cell counts per gram of liver tissue: 2.0±0.4×107 hepatocytes, 1.8±0.5×106 Kupffer cells, 4.3±1.9×105 liver sinusoidal endothelial cells, and 3.2±0.5×105 stellate cells. Hepatocytes were identified by albumin (95.5±1.7%) and exhibited time-dependent activity of cytochrome P450 enzymes. Kupffer cells expressed CD68 (94.5±1.2%) and exhibited phagocytic activity, as determined with 1μm latex beads. Endothelial cells were CD146+ (97.8±1.1%) and exhibited efficient uptake of acetylated low-density lipoprotein. Hepatic stellate cells were identified by the expression of α-smooth muscle actin (97.1±1.5%). These cells further exhibited retinol (vitamin A)-mediated autofluorescence. Conclusions Our isolation procedure for primary parenchymal and non-parenchymal liver cells resulted in cell populations of high purity and quality, with retained physiological functionality in vitro. Thus, this system may provide a valuable tool for determining liver function and disease.
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Huang CF, Sun CC, Zhao F, Zhang YD, Li DJ. miR-33a levels in hepatic and serum after chronic HBV-induced fibrosis. J Gastroenterol 2015; 50:480-90. [PMID: 25155445 DOI: 10.1007/s00535-014-0986-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 07/25/2014] [Indexed: 02/08/2023]
Abstract
BACKGROUND Chronic hepatitis B virus (HBV) infection, which can lead to hepatic disease, has become a critical national healthcare problem, and many people die each year as a result of HBV infection and its complications. Although microRNA-33a (miR-33a) is a novel modulator of lipid and cholesterol metabolism, the role of miR-33a in the hepatic fibrogenesis is still unknown. Here, we aimed to explore the roles and mechanisms of miR-33a in liver fibrosis. METHODS miR-33a expression in whole liver and serum samples was measured from chronic hepatitis B (CHB) patients by quantitative real-time PCR (qRT-PCR). In addition, different murine hepatic fibrosis models were produced to consolidate the results in human tissue. Human and murine primary liver fibrosis-associated cells were isolated and treated with transforming growth factor-β1 (TGF-β1). RESULTS miR-33a expression levels in liver tissue significantly increased with a fibrosis progression manner in the human liver. Furthermore, serum miR-33a levels associated positively with progressing process of hepatic fibrosis. miR-33a was in particular increased in hepatic stellate cells (HSC) than other liver fibrosis-associated cells. Stimulation of HSCs with TGF-β1 leads to a critical increase of miR-33a. Increasing miR-33a levels increased (whereas inhibiting miR-33a weakened) the activation role of TGF-β1 in LX-2 cells, which might be a potential mechanism through moderating Smad7 expression. CONCLUSIONS miR-33a may be a novel marker for HSC activation and hepatic fibrosis progress, suggesting a new therapeutic target in liver fibrosis.
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Affiliation(s)
- Chuan-Feng Huang
- Department of Occupational and Environmental Health, School of Public Health, Wuhan University, Wuhan, 430071, China
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Ikeda N, Murata S, Maruyama T, Tamura T, Nozaki R, Kawasaki T, Fukunaga K, Oda T, Sasaki R, Homma M, Ohkohchi N. Platelet-derived adenosine 5'-triphosphate suppresses activation of human hepatic stellate cell: In vitro study. Hepatol Res 2012; 42:91-102. [PMID: 21988364 DOI: 10.1111/j.1872-034x.2011.00893.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AIM Activated hepatic stellate cells (HSC) play a critical role in liver fibrosis. Suppressing abnormal function of HSC or reversion from activated to quiescent form is a hopeful treatment for liver cirrhosis. The interaction between platelets and HSC remains unknown although platelets go through hepatic sinusoids surrounded by HSC. This study aimed at clarifying the hypothesis that platelets control activation of HSC. METHODS We used human platelets, platelet extracts, and primary or immortalized human HSC. We examined the effect of platelets on the activation, DNA synthesis, type I collagen production, and fibrosis-relating gene expressions of HSC. We investigated what suppressed activation of HSC within platelets and examined the mechanism of controlling activation in vitro. RESULTS Platelets and platelet extracts suppressed activation of HSC. Platelets decreased type I collagen production without affecting DNA synthesis. Platelets increased the expression of matrix metallopeptidase 1. As platelet extracts co-cultured with an enzyme of degrading adenosine 5'-triphosphate (ATP) suppressed activation, we detected adenine nucleotides within platelets or on their surfaces and confirmed the degradation of adenine nucleotides by HSC and the production of adenosine. Adenosine and platelets increased the intracellular cyclic adenosine 5'-monophosphate (cAMP), which is important in quiescent HSC. A great amount of adenosine and ATP also suppressed activation of HSC. CONCLUSION Activation of human HSC is suppressed by human platelets or platelet-derived ATP via adenosine-cAMP signaling pathway in vitro. Therefore, platelets have the possibility to be used in the treatment of liver cirrhosis.
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Affiliation(s)
- Naoya Ikeda
- Departments of Surgery Pharmaceutical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
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Reyes-Gordillo K, Shah R, Popratiloff A, Fu S, Hindle A, Brody F, Rojkind M. Thymosin-β4 (Tβ4) blunts PDGF-dependent phosphorylation and binding of AKT to actin in hepatic stellate cells. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 178:2100-8. [PMID: 21514425 DOI: 10.1016/j.ajpath.2011.01.025] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 12/22/2010] [Accepted: 01/18/2011] [Indexed: 01/18/2023]
Abstract
Hepatic stellate cell transdifferentiation is a key event in the fibrogenic cascade. Therefore, attempts to prevent and/or revert the myofibroblastic phenotype could result in novel therapeutic approaches to treat liver cirrhosis. The expression of platelet-derived growth factor (PDGF)-β receptor and the proliferative response to platelet-derived growth factor-ββ (PDGF-ββ) are hallmarks of the transdifferentiation of hepatic stellate cells (HSC). In this communication, we investigated whether thymosin-β4 (Tβ4), a chemokine expressed by HSC could prevent PDGF-BB-mediated proliferation and migration of cultured HSC. Using early passages of human HSC, we showed that Tβ4 inhibited cell proliferation and migration and prevented the expression of PDGF-β receptor (PDGF-βr), α-smooth muscle actin and α1(I) collagen mRNAs. Tβ4 also inhibited the reappearance of PDGF-βr after its PDGF-BB-dependent degradation. These PDGF-dependent events were associated with the inhibition of AKT phosphorylation at both T308 and S473 amino acid residues. The lack of AKT phosphorylation was not due to the inhibition of PDGF-βr phosphorylation, the activation of phosphoinositide 3-kinase (PI3K), pyruvate dehydrogenase kinase isozyme 1 (PDK1), and mammalian target of rapamycin (mTOR). We found that PDGF-BB induced AKT binding to actin, and that Tβ4 prevented this effect. Tβ4 also prevented the activation of freshly isolated HSC cultured in the presence of Dulbecco's modified Eagle's medium or Dulbecco's minimal essential medium containing 10% fetal bovine serum. In conclusion, overall, our findings suggest that Tβ4 by sequestering actin prevents binding of AKT, thus inhibiting its phosphorylation. Therefore, Tβ4 has the potential to be an antifibrogenic agent.
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Affiliation(s)
- Karina Reyes-Gordillo
- Department of Biochemistry and Molecular Biology, The George Washington University Medical Center, Washington, DC, USA
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