thymosin-beta(4) and Liver-Cirrhosis

Liver fibrosis, a major characteristic of chronic liver disease, is inappropriate tissue remodeling caused by prolonged parenchymal cell injury and inflammation. During liver injury, hepatic stellate cells (HSCs) undergo transdifferentiation from quiescent HSCs into activated HSCs, which promote the deposition of extracellular matrix proteins, leading to liver fibrosis. Thymosin beta 4 (Tβ4), a major actin-sequestering protein, is the most abundant member of the highly conserved β-thymosin family and controls cell morphogenesis and motility by regulating the dynamics of the actin cytoskeleton. Tβ4 is known to be involved in various cellular responses, including antiinflammation, wound healing, angiogenesis, and cancer progression. Emerging evidence suggests that Tβ4 is expressed in the liver; however, its biological roles are poorly understood. Herein, we introduce liver fibrogenesis and recent findings regarding the function of Tβ4 in various tissues and discuss the potential role of Tβ4 in liver fibrosis with a special focus on the effects of exogenous and endogenous Tβ4. Recent studies have revealed that activated HSCs express Tβ4 in vivo and in vitro. Treatment with the exogenous Tβ4 peptide inhibits the proliferation and migration of activated HSCs and reduces liver fibrosis, indicating it has an antifibrotic action. Meanwhile, the endogenously expressed Tβ4 in activated HSCs is shown to promote HSCs activation. Although the role of Tβ4 has not been elucidated, it is apparent that Tβ4 is associated with HSC activation. Therefore, understanding the potential roles and regulatory mechanisms of Tβ4 in liver fibrosis may provide a novel treatment for patients.

Topics: Cell Physiological Phenomena; Cell Transdifferentiation; Gene Expression; Hepatic Stellate Cells; Humans; Liver; Liver Cirrhosis; Liver Diseases; Liver Neoplasms; Signal Transduction; Thymosin

Liver fibrosis, the main characteristic of chronic liver diseases, is strongly associated with the activation of hepatic stellate cells (HSCs), which are responsible for extracellular matrix production. As such, investigating the effective regulators controlling HSC activation provides important clues for developing therapeutics to inhibit liver fibrosis. Thymosin beta 4 (Tβ4), a major actin-sequestering protein, is known to be involved in various cellular responses. A growing body of evidence suggests that Tβ4 has a potential role in the pathogenesis of liver fibrosis and that it is especially associated with the activation of HSCs. However, it remains unclear whether Tβ4 promotes or suppresses the activation of HSCs. Herein, we review the potential role of Tβ4 in liver fibrosis by describing the effects of exogenous and endogenous Tβ4, and we discuss the possible signaling pathway regulated by Tβ4. Exogenous Tβ4 reduces liver fibrosis by inhibiting the proliferation and migration of HSCs. Tβ4 is expressed endogenously in the activated HSCs, but this endogenous Tβ4 displays opposite effects in HSC activation, either as an activator or an inhibitor. Although the role of Tβ4 has not been established, it is apparent that Tβ4 influences HSC activation, suggesting that Tβ4 is a potential therapeutic target for treating liver diseases.

Topics: Animals; Hepatic Stellate Cells; Humans; Liver; Liver Cirrhosis; Signal Transduction; Thymosin

Liver fibrosis is a grievous global challenge, where hepatic stellate cells (HSCs) activation is a paramount step. This study analyzed the mechanism of Tβ4 in ameliorating liver fibrosis via the MAPK/NF-κB pathway. The liver fibrosis mouse models were established via bile duct ligation (BDL) and verified by HE and Masson staining. TGF-β1-induced activated LX-2 cells were employed in vitro experiments. Tβ4 expression was determined using RT-qPCR, HSC activation markers were examined using Western blot analysis, and ROS levels were tested via DCFH-DA kits. Cell proliferation, cycle, and migration were examined by CCK-8, flow cytometry, and Transwell assays, respectively. Effects of Tβ4 on liver fibrosis, HSC activation, ROS production, and HSC growth were analyzed after transfection of constructed Tβ4-overexpressing lentiviral vectors. MAPK/NF-κB-related protein levels were tested using Western blotting and p65 expression in the nucleus was detected through immunofluorescence. Regulation of MAPK/NF-κB pathway in TGF-β1-induced LX-2 cells was explored by adding MAPK activator U-46619 or inhibitor SB203580. Furthermore, its regulating in liver fibrosis was verified by treating BDL mice overexpressing Tβ4 with MAPK inhibitor or activator. Tβ4 was downregulated in BDL mice. Tβ4 overexpression inhibited liver fibrosis. In TGF-β1-induced fibrotic LX-2 cells, Tβ4 was reduced and cell migration and proliferation were enhanced with elevated ROS levels, while Tβ4 overexpression suppressed cell migration and proliferation. Tβ4 overexpression blocked the MAPK/NF-κB pathway activation by reducing ROS production, thus inhibiting liver fibrosis in TGF-β1 induced LX-2 cells and BDL mice. Tβ4 ameliorates liver fibrosis by impeding the MAPK/NF-κB pathway activation.

Topics: Animals; Hepatic Stellate Cells; Liver; Liver Cirrhosis; Mice; NF-kappa B; Reactive Oxygen Species; Transforming Growth Factor beta1

Liver fibrosis is an important health problem without adequate and effective therapeutics. In this study, effects of thymosinβ4 (Tβ4) on hepatic fibrogenesis and the underlying molecular mechanisms were explored in bile duct ligation (BDL)-induced mice cholestatic liver fibrosis model. Results showed exogenous Tβ4 significantly reduced the mortality and liver/body weight ratio in BDL mice. Histological examinations and biochemical analyses demonstrated that BDL induced evident portal fibrosis and a significant increase in hepatic collagen contents. However, these changes were significantly attenuated by exogenous Tβ4. Quantitative real-time PCR assays showed that Tβ4 suppressed BDL-induced increases in many fibrotic genes expression including α-smooth muscle actin (α-SMA), collagen I, III and fibronectin, TGFβ1, TGFβR II, Smad2, Smad3, and PDGFRβ. Results from immunohistochemistry and Western blots also showed that Tβ4 reduced TGFβ1 and PDGFRβ protein levels in the liver tissues of BDL mice. In vitro studies using LX-2 cells demonstrated that Tβ4 could decrease PDGFRβ and TGFβR II levels in hepatic stellate cells. Taken together, findings in our present studies suggested that exogenous Tβ4 alleviated BDL-induced cholestatic liver fibrosis through downregulating PDGF/PDGFR and TGFβ/Smad pathways.

Topics: Animals; Collagen Type I; Cytokines; Down-Regulation; Hepatic Stellate Cells; Liver; Liver Cirrhosis; Male; Mice; Mice, Inbred BALB C; Platelet-Derived Growth Factor; Receptor, Platelet-Derived Growth Factor beta; Signal Transduction; Smad Proteins; Thymosin; Transforming Growth Factor beta

Hepatic injury is one of the most challenging diseases in clinical medicine. Hepatic injury is accompanied by hepatocyte apoptosis and leads to hepatic fibrosis and cirrhosis, which may cause liver cancer and increased mortality. Therefore, it is essential to investigate the regulation mechanism and therapeutic strategies for hepatic injury. In the study, the effects of Thymosin β4 (Tβ4) on Long intergenic noncoding RNA-p21 (lincRNA-p21)-mediated liver injury were investigated. Results showed that lincRNA-p21 overexpression promoted hepatocytes apoptosis, which was blocked by Tβ4. Besides, Tβ4 reversed the levels of cleaved caspase-3 and caspase-9 induced by lincRNA-p21. LincRNA-p21 overexpression also caused the pathological injury and fibrosis in hepatic tissues and increased the levels of fibrosis-related proteins (Collagen I, α-SMA and TIMP-1), and induced hydroxyproline and ALT production. However, Tβ4 reversed the effects of overexpression of lincRNA-p21 on hepatic injury and fibrosis. In vitro experiments, after lincRNA-p21 was overexpressed in hepatic stellate cells (HSCs), the proliferation ability and the levels of HSCs markers α-SMA and Desmin were increased. However, Tβ4 reversed the effects of lincRNA-p21 on HSCs. Furthermore, the PI3K-AKT-NF-κB pathway was activated by lincRNA-p21, which was then reversed by the Tβ4 administration. After the mice treated by insulin-like growth factor-1 (IGF-1) (the activator of PI3K-AKT), the inhibitory effect of Tβ4 on activated the PI3K-AKT-NF-κB pathway was abrogated. Besides, IGF-1 abolished the protective effects of Tβ4 on hepatic apoptosis and fibrosis induced by lincRNA-p21. Therefore, Tβ4 reversed. lincRNA-p21-mediated liver injury through inhibiting PI3K-AKT-NF-κB pathway. Tβ4 may be a promising drug for fibrosis therapy.

Topics: Actins; Animals; Apoptosis; Cell Proliferation; Collagen; Hepatocytes; I-kappa B Proteins; Liver; Liver Cirrhosis; Mice; Mice, Inbred C57BL; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; RNA, Long Noncoding; Thymosin; Tissue Inhibitor of Metalloproteinase-1

To investigate the inhibitory effect of thymosin-β4 (Tβ4) on the activation of the human hepatic stellate cell line (HSC-LX2) induced by interleukin (IL)-1β.. There were 5 groups in this study, i.e., blank control group, negative control group (SI-NC, empty plasmid), model group (20 ng/ml of IL-1β), siRNA-Tβ4 knockdown group (IL-1β and si-Tβ4) and Tβ4 treatment group (IL-1β and 1000 ng/ml of Tβ4). Cell proliferation rate was measured using the Cell Counting Kit-8 (CCK-8) method. The cell cycle change and percentage of apoptotic cells were determined by Propidium Iodide (PI) DNA staining and Annexin V-fluorescein isothiocyanate (FITC) double staining. Cellular nucleic acid levels of p-IKB and nuclear factor-kappa B (NF-κB)/p65 proteins were measured by fluorescent quantitative Real Time-Polymerase Chain Reaction (RT-PCR). Double immunofluorescence staining and Western blot were used to detect nuclear translocation of NF-κB and p65 and levels of cytoplasmic p-IKB protein and nuclear p65 protein.. Due to the G0/G1 phase arrest, the number of cells in the Tβ4 treatment group increased, compared with the model group and the siRNA-Tβ4 knockdown group (p<0.01). In the same between-group comparison, apoptotic rate in the Tβ4 treatment group increased significantly (p<0.05). The cellular nucleic acid levels of p-IKB and NF-κB/p65 were markedly higher in the model group and the siRNA-Tβ4 knockdown group than in the blank control group (p<0.01). The cellular nucleic acid levels of p-IKB and NF-κB/p65 were remarkably lower in the Tβ4 treatment group than in the siRNA-Tβ4 knockdown group (p<0.01). The expression levels of NF-κB/p65 and NF-κB/p50 were significantly lower in the Tβ4 treatment group. The expression levels of cytoplasmic p-IKB and nuclear NF-κB/p65 were lower in the Tβ4 treatment group than in the model group (p<0.01).. Tβ4 significantly inhibited IL-1β-induced HSC-LX2 cell proliferation. The mechanism may involve decreased activation of the NF-κB pathway, decreased expression of p-IKB and nuclear translocation of p65. Therefore, Tβ4 had the effect of reversing liver fibrosis.

Topics: Animals; Cell Line; Cell Proliferation; Gene Knockdown Techniques; Hepatic Stellate Cells; Interleukin-1beta; Liver Cirrhosis; Rats; RNA, Small Interfering; Signal Transduction; Thymosin; Transcription Factor RelA

The present study aimed to clarify the effects of thymosin β4 (Tβ4) on CCl. Expression of Tβ4 in fibrotic liver tissues was assessed by a quantitative real time-reverse transcriptase polymerase chain reaction and immunohistochemistry. The effects of intraperitoneal adeno-associated virus-Tβ4 (AAV-Tβ4) on CCl. The expression of Tβ4 was down-regulated in fibrotic mouse livers but was rapidly up-regulated by CCl. Tβ4 possesses anti-fibrotic activity in the liver, which is attributable, at least partly, to down-regulating TGF-βRII and thereby blunting TGF-β1-mediated fibrogenetic signaling in both HSCs and hepatocytes.

Topics: Animals; Carbon Tetrachloride; Cell Proliferation; Dependovirus; Down-Regulation; Gene Expression Regulation; Hepatic Stellate Cells; Hepatocytes; Humans; Liver; Liver Cirrhosis; Male; Mice; Receptor, Transforming Growth Factor-beta Type II; Thymosin; Transforming Growth Factor beta1

Hepatic stellate cells (HSC) trans-differentiation is central to the development of liver fibrosis, marked by the expression of pro-fibrogenic genes and the proliferation and migration of activated HSC. Therefore, preventing and/or reverting the activation, proliferation, and migration of HSC may lead to new therapies for treating fibrosis/cirrhosis. Thymosin β4 (Tβ4) inhibits PDGF-BB-induced fibrogenesis, proliferation and migration of HSC by blocking Akt phosphorylation. Here, we utilized Tβ4-derived peptides: amino-terminal-Ac-SDKPDMAEIEKFDKS (1-15aa) and actin-binding-LKKTETQ (17-23aa) to investigate the molecular mechanisms in the anti-fibrogenic actions of Tβ4.. We used RT-PCR, Western blot, and proliferation and migration assays in early passages of human HSC cultures treated with PDGF-BB and/or Tβ4 peptides.. We showed that 17-23aa but not 1-15aa inhibited PDGF-BB-dependent up-regulation of PDGFβ receptor, α-SMA, and collagen 1. It also blunted the phosphorylation of Akt at T 308 and S473, resulting in the inhibition of phosphorylation of PRAS40, and HSC proliferation and migration. Interestingly, 1-15aa blocked Akt phosphorylation at S473, but not T308 by inhibiting mTOR phosphorylation, thus, it did not have any effect on HSC proliferation and migration.. These findings suggest that while 1-15aa has a minor effect on Akt phosphorylation, the anti-fibrogenic actions of Tβ4 are exerted via 17-23aa.

Topics: Actins; Animals; Becaplermin; Cell Movement; Cell Proliferation; Cells, Cultured; Hepatic Stellate Cells; Humans; Liver Cirrhosis; Phosphorylation; Protein Binding; Protein Interaction Domains and Motifs; Thymosin

Hepatic stellate cells (HSCs) are the primary cell type responsible for liver fibrosis. Our study proved that thymosin beta 4 (Tβ4) has anti-fibrogenic effects in HSCs through PI3K/AKT pathway. However, the underlying mechanisms are not fully elucidated. Circular RNAs (circRNAs) play important roles in fine-tuning gene expression and are often deregulated in cancers. However, the expression profile and clinical significance of in liver fibrosis is still unknown. Therefore, we hypothesize that Tβ4 influences circRNAs in liver fibrosis.. Circular RNA microarray was conducted to identify Tβ4-related circRNAs. Pathway analysis and miRNA response elements analysis was conducted to predict the potential roles of differentially expressed circRNAs in liver fibrosis. CCK8 assays and flow cytometric assays were conducted to clarify the role of circRNA in liver fibrosis. Bioinformatics analysis and in vitro experiments were conducted to clarify the mechanism of circRNA-mediated gene regulation in liver fibrosis.. A total of 644 differentially expressed circRNAs were identified between the Tβ4-depleted LX-2 cells and the control LX2 cells. The expression of circRNA-0067835 was significantly increased in the Tβ4-depleted LX-2 cells compared with control. Knockdown of circRNA-0067835 observably decreased LX-2 cell proliferation by causing G1 arrest and promoting apoptosis. Bioinformatics online programs predicted that circRNA-0067835 acted as miR-155 sponge to regulate FOXO3a expression, which was validated using luciferase reporter assay.. Our experiments showed that circRNA-0067835 regulated liver fibrosis progression by acting as a sponge of miR-155 to promote FOXO3a expression, indicating that circRNA-0067835 may serve as a potential therapeutic target for patients with liver fibrosis.

Topics: Animals; Cell Line; Cells, Cultured; Forkhead Box Protein O3; Gene Expression Regulation; Hepatic Stellate Cells; Humans; Liver Cirrhosis; Male; Mice, Inbred C57BL; MicroRNAs; RNA; RNA, Circular; Signal Transduction; Thymosin; Transcriptome

The present study investigated the effects of exogenous thymosin β4 (TB4) on carbon tetrachloride (CCl

Topics: Acute Disease; Alanine Transaminase; Animals; Aspartate Aminotransferases; Carbon Tetrachloride; Inflammation; Interleukin-1beta; Liver; Liver Cirrhosis; Male; Mice, Inbred BALB C; Oxidative Stress; Rats, Sprague-Dawley; Thymosin; Transcription Factor RelA; Transforming Growth Factor beta1; Tumor Necrosis Factor-alpha

The aim of the study was to detect the expression level of thymosin β4 (Tβ4) in serum and tissues of patients with chronic hepatitis B (CHB) combined nonalcoholic fatty liver disease (NAFLD). The effects of Tβ4 in hepatic steatosis, chronic inflammation, and fibrosis development in CHB combined NAFLD patients were also discussed. The study included 46 patients in the case group with CHB and NAFLD and 42 patients in the control group with CHB. ELISA was applied to detect serum Tβ4 and TNF-α level. Furthermore, the correlation analysis of Tβ4 levels with biochemical index, pathological index, and TNF-α level was performed. The Tβ4 immunohistochemical levels of different inflammation fibrosis levels were compared, and the correlation analysis with TNF expression was performed. The Tβ4 levels in patients with CHB combined NAFLD showed no statistical difference when compared to the control group. In patients with CHB combined NAFLD group, the Tβ4 level had no correlation with ALT, AST, TG, FGP, hepatitis B virus (HBV)-DNA levels, and fat grading, but had negative correlation with inflammation score and fibrosis score (P <0.01). The immunohistochemical results of hepatic tissues showed that the expression intensity of severe inflammation fibrosis group had statistical significance compared with that of slight group, and the Tβ4 expression both in serum and in liver tissue negatively correlated with TNF-α expression. Tβ4 could be involved in the regulation of chronic inflammation and fibrosis and plays a defense role in the disease progression of CHB combined NAFLD patients.

Topics: Adult; Female; Hepatitis B, Chronic; Humans; Liver Cirrhosis; Male; Middle Aged; Non-alcoholic Fatty Liver Disease; Thymosin; Tumor Necrosis Factor-alpha

The purpose of our work was to identify unknown interaction partners of thymosin β4 (Tβ4). It was suggested that Tβ4 could be an antifibrotic drug for treatment of liver fibrogenesis, because Tβ4 prevents the platelet-derived growth factor-BB (PDGF-BB)-induced activation of hepatic stellate cells (HSCs). Very little information is available how Tβ4 counteracts the PDGF-BB-induced activation of HSCs. We propose the hypothesis that Tβ4 could bind directly to PDGF-BB and thereby reduce the concentration of free PDGF-BB available for binding to the PDGF-β receptor.. To prove our suggestion of a direct interaction between Tβ4 and PDGF-BB, we carried out chemical as well as photochemical cross-linking experiments between the two pure proteins in vitro.. We identified an interaction between Tβ4 and PDGF-BB by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) cross-linking as well as through biotin label transfer using a bifunctional photoactivatable derivative of Tβ4. In an in vitro system, PDGF-BB was identified as the first extracellular partner interacting with Tβ4. This interaction could influence PDGF-BB binding to its receptor and abolish PDGF-BB-related effects.. Direct interaction of Tβ4 with extracellular factors should be considered as a potential mechanism to explain the pleiotropic effects of β-thymosins.

Topics: Amino Acid Sequence; Becaplermin; Cell Proliferation; Cells, Cultured; Cross-Linking Reagents; Humans; Liver Cirrhosis; Molecular Sequence Data; Protein Binding; Proto-Oncogene Proteins c-sis; Thymosin

It has recently been reported that thymosin beta-4 (Tβ4) has anti-fibrogenic effects in human hepatic stellate cells (HSCs) in vitro, but the mechanisms underlying these effects remain unclear. The aim of this study was to investigate the roles of Tβ4 in the proliferation, migration, and activation of HSCs.. Enzyme-linked immunosorbent assays (ELISA), immunohistochemistry, and western blot assays were utilized to determine the expression levels of Tβ4 in serum, liver tissues, and LX-2 cells. Tβ4 was depleted in LX-2 cells using small interfering RNAs (siRNAs). Cell proliferation was analyzed using cell counting kit-8 (CCK-8) viability assays, and cell migration was investigated using wound-healing and transwell migration assays.. The expression of Tβ4 was significantly reduced during the progression of liver fibrosis. The depletion of Tβ4 significantly promoted the proliferation and migration of LX-2 cells via the activation of the PI3K/Akt signaling pathway. The pro-migratory and pro-proliferative effects of Tβ4 depletion in LX-2 cells can be counteracted by treatment with the Akt inhibitor MK-2206. In addition, Tβ4 depletion was also associated with the activation of HSCs via the enhanced expression of α-smooth muscle actin (α-SMA) and vimentin.. Our results suggest that Tβ4 participates in liver fibrosis by inhibiting the migration, proliferation, and activation of HSCs and that Tβ4 may be an effective target in the treatment of liver fibrosis.

Topics: Actins; Animals; Cell Line; Cell Movement; Cell Proliferation; Disease Progression; Hepatic Stellate Cells; Humans; Liver Cirrhosis; Male; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; RNA, Small Interfering; Signal Transduction; Thymosin; Vimentin

Thymosin β4 (Tβ4) plays a role in fibrosis, inflammation, and in the reparative process of injured cells and tissues. Here, we discuss our preliminary work on the protective effect of Tβ4 on carbon tetrachloride (CCl(4) )-induced acute hepatotoxicity. Our studies thus far indicate that Tβ4 can prevent necrosis, inflammatory infiltration, and upregulation of α1(and 2) collagen, α-SMA, PDGF-β receptor, and fibronectin mRNA expression; in addition, Tβ4 can prevent downregulation of PPARγ and upregulation of MECP2 mRNA levels in acute liver injury. Our initial work therefore indicates that Tβ4 can prevent the alteration of markers of hepatic stellate cell transdifferentiation, which suggests that Tβ4 could maintain the quiescent phenotypic state of hepatic stellate cells in the rat livers by restoring PPARγ and downregulating MeCP2 expression levels. More specifically, these preliminary studies suggest that Tβ4 might be an effective anti-inflammatory and antifibrotic drug for the treatment of liver fibrogenesis.

Topics: Animals; Anti-Inflammatory Agents; Carbon Tetrachloride; Collagen; Liver; Liver Cirrhosis; PPAR gamma; Rats; Receptor, Platelet-Derived Growth Factor beta; Thymosin

Despite tremendous efforts in disclosing the pathophysiological and epidemiological factors associated with liver fibrogenesis, non-invasive diagnostic measures to estimate the clinical outcome and progression of liver fibrogenesis are presently limited. Therefore, there is a mandatory need for methodologies allowing the reasonable and reliable assessment of the severity and/or progression of hepatic fibrogenesis. We here performed proteomic serum profiling by matrix-assisted laser desorption ionization time-of-flight mass spectrometry in 179 samples of patients chronically infected with hepatitis C virus and 195 control sera. Multidimensional analysis of spectra allowed the definition of algorithms capable to distinguish class-specific protein expression profiles in serum samples. Overall about 100 peaks could be detected per single spectrum. Different algorithms including protein peaks in the range of 2000 and 10,000 Da were generated after pre-fractionation on a weak cation exchange surface. A specificity of 93% with a sensitivity of 86% as mean of the test set results was found, respectively. The nature of three of these protein peaks that belonged to kininogen-1 and thymosin-β(4) was further analysed by tandem mass spectrometry (MS)/MS. We further found that kininogen-1 mRNA was significantly down-regulated in cirrhotic livers. We have identified kininogen-1 and thymosin-β(4) as potential new biomarkers for human chronic hepatitis C and conclude that serum profiling is a reliable technique to identify hepatitis-associated expression patterns. Based on the high throughput capability, the identified differential protein panel may serve as a diagnostic marker and warrants further validation in larger cohorts.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Biomarkers; Child; Female; Hepatitis C; Humans; Kininogens; Liver; Liver Cirrhosis; Male; Middle Aged; Proteomics; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Thymosin; Young Adult

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.

Topics: Actins; Becaplermin; Blotting, Western; Cell Movement; Cell Proliferation; Cell Separation; Cell Transdifferentiation; Flow Cytometry; Fluorescent Antibody Technique; Hepatic Stellate Cells; Humans; Immunoprecipitation; Liver Cirrhosis; Phosphorylation; Platelet-Derived Growth Factor; Protein Binding; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-sis; Reverse Transcriptase Polymerase Chain Reaction; Thymosin