TGF-beta isoforms in alcoholic liver disease

Myricetin Ameliorates Ethanol-Induced Lipid Accumulation in Liver Cells by Reducing Fatty Acid Biosynthesis

SCOPE

Alcoholic liver disease is a serious threat to human health. The development of drug candidates from complementary and alternative medicines is an attractive approach. Myricetin can be found in fruit, vegetables, and herbs. This study investigates the protective effect of myricetin on ethanol-induced injury in mouse liver cells.

METHODS AND RESULTS

Oil-red O staining, assays of oxidative stress and measurements of inflammatory markers in mouse AML12 liver cells collectively demonstrate that myricetin elicits a curative effect on ethanol-induced injury. Next, the role of myricetin in the metabolic regulation of ethanol pathology in liver cells is assessed by gas chromatography coupled with mass spectrometry. Myricetin inhibits ethanol-stimulated fatty acid biosynthesis. Additionally, dodecanoic acid may be proposed as a potential biomarker related to ethanol pathology or myricetin therapy. It is also observed that myricetin enhances ethanol-induced inhibition of the mitochondrial electron transport chain. Moreover, fumaric acid is found to be a candidate biomarker related to ethanol toxicity or myricetin therapy. Quantitative reverse-transcription-PCR shows that ethanol-induced fatty acid synthase and sterol regulatory element-binding protein-1c mRNA levels are alleviated by myricetin. Finally, myricetin increases ethanol-induced inhibition of phosphorylation of AMP-activated protein kinase.

CONCLUSION

These results elucidate the pharmacological mechanism of myricetin on ethanol-induced lipid accumulation.

MicroRNAs in alcoholic liver disease: Recent advances and future applications

Alcoholic liver disease (ALD) is characterized by hepatocyte damage, inflammatory cell activation, and increased intestinal permeability leading to the clinical manifestations of alcoholic hepatitis. Selected members of the family of microRNAs (miRNAs) are affected by alcohol, resulting in an abnormal miRNA profile in the liver and circulation in ALD. Increasing evidence suggests that miRNAs that regulate inflammation, lipid metabolism and promote cancer are affected by excessive alcohol administration in mouse models of ALD. This communication highlights recent findings in miRNA expression and functions as they relate to the pathogenesis of ALD. The cell-specific distribution of miRNAs, as well as the significance of circulating extracellular miRNAs, is discussed as potential biomarkers. Finally, the prospects of miRNA-based therapies are evaluated in ALD.

Liver fibrosis in bile duct-ligated rats correlates with increased hepatic IL-17 and TGF-β2 expression

BACKGROUND AND RATIONALE FOR THE STUDY: IL-17, TGF-β1/2 are cytokines involved in the development of kidney, pulmonary and liver fibrosis. However, their expression kinetics in the pathogenesis of cholestatic liver fibrosis have not yet been fully explored. The aim of the study was to analyze the expression of IL-17, RORγt, NKp46, TGF-β1, and TGF-β2 in the liver of rats with bile duct ligation (BDL).

RESULTS

Hepatic IL-17A gene expression analyzed by qRT-PCR showed a dramatic increase of 350 and 10 fold, at 8 and 30 days post BDL, respectively. TGFβ1 and TGFβ2 gene expression significantly increased throughout the whole fibrotic process. At the protein level in liver homogenates, IL-17, TGF-β1, and RORγt significantly increased at 8 and 30 days after BDL. Interestingly, a significant increase in the protein levels of TGF-β2 and decrease of NKp46 was observed only 30 days after BDL. Unexpectedly, TGF-β2 exhibited stronger signals than TGF-β1 at the gene expression and protein levels. Histological analysis showed bile duct proliferation and collagen deposition.

CONCLUSIONS

Our results suggest that pro-fibrogenic cytokines IL-17, TGF-β1 and, strikingly, TGF-β2 might be important players of liver damage in the pathogenesis of early and advanced experimental cholestatic fibrosis. Th17 cells might represent an important source of IL-17, while NK cell depletion may account for the perpetuation of liver damage in the BDL model.

The Effector Protein BPE005 from Brucella abortus Induces Collagen Deposition and Matrix Metalloproteinase 9 Downmodulation via Transforming Growth Factor β1 in Hepatic Stellate Cells

The liver is frequently affected in patients with active brucellosis. In the present study, we identified a virulence factor involved in the modulation of hepatic stellate cell function and consequent fibrosis during Brucella abortus infection. This study assessed the role of BPE005 protein from B. abortus in the fibrotic phenotype induced on hepatic stellate cells during B. abortus infection in vitro and in vivo. We demonstrated that the fibrotic phenotype induced by B. abortus on hepatic stellate (LX-2) cells was dependent on BPE005, a protein associated with the type IV secretion system (T4SS) VirB from B. abortus. Our results indicated that B. abortus inhibits matrix metalloproteinase 9 (MMP-9) secretion through the activity of the BPE005-secreted protein and induces concomitant collagen deposition by LX-2 cells. BPE005 is a small protein containing a cyclic nucleotide monophosphate binding domain (cNMP) that modulates the LX-2 cell phenotype through a mechanism that is dependent on the cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway. Altogether, these results indicate that B. abortus tilts LX-2 cells to a profibrogenic phenotype employing a functional T4SS and the secreted BPE005 protein through a mechanism that involves the cAMP and PKA signaling pathway.

Role of intestinal myofibroblasts in HIV-associated intestinal collagen deposition and immune reconstitution following combination antiretroviral therapy

OBJECTIVE

To investigate the potential role of mucosal intestinal myofibroblasts (IMFs) in HIV and associated fibrosis in gut-associated lymphoid tissue.

DESIGN

Profibrotic changes within the secondary lymphoid organs and mucosa have been implicated in failed immune reconstitution following effective combination antiretroviral therapy (cART). Microbial translocation is believed to be sustaining these systemic inflammatory pathways. IMFs are nonprofessional antigen-presenting cells with both immunoregulatory and mesenchymal functions that are ideally positioned to respond to translocating microbial antigen.

METHODS

Duodenal biopsies, obtained from patients naive to cART, underwent trichrome staining and were examined for tissue growth factor-beta (TGF-β) expression. Combined immunostaining and second harmonic generation analysis were used to determine IMF activation and collagen deposition. Confocal microscopy was performed to examine IMF activation and Toll-like receptor (TLR)4 expression. Finally, primary IMF cultures were stimulated with lipopolysaccharide to demonstrate the expression of the inflammatory biomarkers.

RESULTS

The expression of the fibrosis-promoting molecule, TGF-β1, is significantly increased in duodenal biopsies from HIV patients naïve to cART, and negatively correlated with subsequent peripheral CD4(+) recovery. The increase in TGF-β1 coincided with an increase in collagen deposition in the duodenal mucosa in the tissue area adjacent to the IMFs. We also observed that IMFs expressed TLR4 and had an activated phenotype since they were positive for fibroblast activation protein. Finally, stimulation of IMFs from HIV patients with TLR4 resulted in significantly increased expression of profibrotic molecules, TGF-β1, and interleukin-6.

CONCLUSION

Our data support the hypothesis that activated IMFs may be among the major cells contributing to the profibrotic changes, and thus, the establishment and maintenance of systemic inflammation interfering with immune reconstitution in HIV patients.

AMP-activated protein kinase inhibits TGF-β-induced fibrogenic responses of hepatic stellate cells by targeting transcriptional coactivator p300

Liver fibrosis is a common consequence of various chronic liver injuries, including virus infection and ethanol. Activated hepatic stellate cells (HSCs) contribute to liver fibrosis through the accumulation of extracellular matrix proteins, including type I alpha collagen (COL1A). The activation of adenosine monophosphate-activated protein kinase (AMPK) modulates HSCs activation, but its underlying mechanism remains unclear. Here, we report that AMPK inhibits transforming growth factor (TGF)-β-induced fibrogenic property of HSCs by regulating transcriptional coactivator p300. We treated human (LX-2) and rat (CFSC-2G) HSC lines with TGF-β to induce fibrogenic activation of HSCs. Pharmacological activation of AMPK by treatment with 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), metformin, or adiponectin lowered TGF-β-induced expression of COL1A and myofibroblast marker alpha-smooth muscle actin (α-SMA). Transient transduction of constitutively active AMPKα (caAMPKα) was sufficient to attenuate COL1A and α-SMA expression, whereas an AMPK inhibitor considerably abrogated the inhibitory effect of AICAR on fibrogenic gene expression. Although AMPK significantly suppressed Smad-dependent transcription, it did not affect TGF-β-stimulated phosphorylation, nuclear localization, or DNA-binding activity of Smad2/3. AICAR rather attenuated TGF-β-induced Smad3 interaction with transcriptional coactivator p300 accompanying with reduction of Smad3 acetylation. Moreover, AICAR induced not only physical interaction between AMPK and p300 but also proteasomal degradation of p300 protein. Our data provide substantial evidence that AMPK could be a novel therapeutic target for treatment of liver fibrosis, by demonstrating the underlying mechanism of AMPK-induced antifibrotic function in HSCs.

TGF-beta enhances alcohol dependent hepatocyte damage via down-regulation of alcohol dehydrogenase I

BACKGROUND & AIMS

Adverse alcohol effects in the liver involve oxidative metabolism, fat deposition and release of fibrogenic mediators, including TGF-beta. The work presents an assessment of liver damaging cross-talk between ethanol and TGF-beta in hepatocytes.

METHODS

To investigate TGF-beta effects on hepatocytes, microarray analyses were performed and validated by qRT-PCR, Western blot analysis and immunohistochemistry. The cellular state was determined by assessing lactate dehydrogenase, cellular glutathione, reactive oxygen species, lipid peroxidation and neutral lipid deposition. RNA interference was used for gene silencing in vitro.

RESULTS

TGF-beta is induced in mouse livers after chronic ethanol insult, enhances ethanol induced oxidative stress and toxicity towards cultured hepatocytes plus induces lipid-, oxidative stress metabolism- and fibrogenesis-gene expression signatures. Interestingly, TGF-beta down-regulates alcohol metabolizing enzyme Adh1 mRNA in cultured hepatocytes and liver tissue from TGF-beta transgenic mice via the ALK5/Smad2/3 signalling branch, with Smad7 as a potent negative regulator. ADH1 deficiency is a determining factor for the increased lipid accumulation and Cyp2E1 dependent toxicity in liver cells upon alcohol challenge. Further, ADH1 expression was decreased during liver damage in an intragastric ethanol infusion mouse model.

CONCLUSION

In the presence of ethanol, TGF-beta displays pro-steatotic action in hepatocytes via decreasing ADH1 expression. Low ADH1 levels are correlated with enhanced hepatocyte damage upon chronic alcohol consumption by favoring secondary metabolic pathways.

Identification of peptide inhibitors of transforming growth factor beta 1 using a phage-displayed peptide library

Pathologies such as liver fibrosis and scleroderma are characterized by harmful levels of transforming growth factor beta 1 (TGFbeta1). These levels could be neutralized if inhibitors of this cytokine were available. With this aim we searched for peptides with binding affinity for TGFbeta1 using a phage-displayed random 15-mer peptide library. Some peptides thus identified blocked activity of TGFbeta1 in vitro, as measured by their capacity to restore growth of Mv-1-Lu cells in presence of added TGFbeta1. Also, they inhibited TGFbeta1-dependent expression of collagen type I mRNA in liver of mice orally insulted with CCl(4). Intraperitoneal administration of 50 microg of peptide P17 (the most active 15-mer peptide, also referred to as P17(1-15)) inhibited expression of collagen type I mRNA by almost 100%. Interestingly, titration experiments showed that P17(1-12) (a peptide encompassing the first 12 amino acids of P17) was approximately four times more active than P17. These results suggest that both peptides, as well as others reported here, may be of therapeutic interest in processes requiring control of undesired high levels of TGFbeta1.

Disruption of transforming growth factor-beta signaling by curcumin induces gene expression of peroxisome proliferator-activated receptor-gamma in rat hepatic stellate cells

Activation of hepatic stellate cells (HSC), the major effectors of hepatic fibrogenesis, is coupled with sequential alterations in gene expression, including an increase in receptors for transforming growth factor-beta (TGF-beta) and a dramatic reduction in the peroxisome proliferator-activated receptor-gamma (PPAR-gamma). The relationship between them remains obscure. We previously demonstrated that curcumin induced gene expression of PPAR-gamma in activated HSC, leading to reducing cell proliferation, inducing apoptosis and suppressing expression of extracellular matrix genes. The underlying molecular mechanisms are largely unknown. We recently observed that stimulation of PPAR-gamma activation suppressed gene expression of TGF-beta receptors in activated HSC, leading to the interruption of TGF-beta signaling. This observation supported our assumption of an antagonistic relationship between PPAR-gamma activation and TGF-beta signaling in HSC. In this study, we further hypothesize that TGF-beta signaling might negatively regulate gene expression of PPAR-gamma in activated HSC. The present report demonstrates that exogenous TGF-beta1 inhibits gene expression of PPAR-gamma in activated HSC, which is eliminated by the pretreatment with curcumin likely by interrupting TGF-beta signaling. Transfection assays further indicate that blocking TGF-beta signaling by dominant negative type II TGF-beta receptor increases the promoter activity of PPAR-gamma gene. Promoter deletion assays, site-directed mutageneses, and gel shift assays localize two Smad binding elements (SBEs) in the PPAR-gamma gene promoter, acting as curcumin response elements and negatively regulating the promoter activity in passaged HSC. The Smad3/4 protein complex specifically binds to the SBEs. Overexpression of Smad4 dose dependently eliminates the inhibitory effects of curcumin on the PPAR-gamma gene promoter and TGF-beta signaling. Taken together, these results demonstrate that the interruption of TGF-beta signaling by curcumin induces gene expression of PPAR-gamma in activated HSC in vitro. Our studies provide novel insights into the molecular mechanisms of curcumin in the induction of PPAR-gamma gene expression and in the inhibition of HSC activation.

Polymorphisms in the transforming growth factor-beta gene (TGF-beta) and the risk of advanced alcoholic liver disease

BACKGROUND/AIMS

There are wide interindividual differences in the risk of developing alcoholic cirrhosis. Transforming growth factor beta(1) (TGF-beta(1)) is the main cytokine involved in liver fibrogenesis. The TGF-beta(1) gene is polymorphic at several sites and these polymorphisms are probably related to differences in the rate of TGF-beta(1) synthesis. Our aim has been to analyse the influence of the TGF-beta(1) gene polymorphisms in the predisposition to advanced alcoholic liver disease (ALD) in ethanol abusers.

METHODS

TGF-beta(1) single nucleotide polymorphisms at positions -509 (C or T), +869 (C or T, codon 10), and +915 (C or G, codon 25) were examined in 165 alcoholics with advanced ALD and in 185 healthy controls.

RESULTS

Among the 94 male patients with oesophageal varices, those carrying the GG genotype at position +915 were diagnosed at an older age than the remaining patients (age 52.1 years, standard deviation (SD) 9.9 vs. 45 SD 13.4, P=0.012). No other statistically significant differences were found in the distribution of the three TGF-beta(1) polymorphisms analysed individually or as combined haplotypes.

CONCLUSIONS

The polymorphisms at the TGF-beta(1) gene analysed in this study are probably not related to the risk of advanced ALD.

Effects of Hochu‐ekki‐to and Ninjin‐youei‐to, Traditional Japanese Medicines, on Porcine Serum‐Induced Liver Fibrosis in Rats

In this study, we estimated the effects of traditional Japanese medicines on liver fibrosis in Wistar rats injected with porcine serum twice a week for 8 weeks. The rats were orally administered Hochu-ekki-to, Ninjin-youei-to (100 and 300 mg/kg/day) or Sho-saiko-to (300 mg/kg/day) 5 days per week. Serum and liver samples were obtained 2 days after the last porcine serum injection. Hochu-ekki-to and Ninjin-youei-to showed significant suppressive effects on the increase in hepatic hydroxyproline, namely total collagen. Further, Ninjin-youei-to significantly suppressed the increases of type IV collagen localized in the basement membrane and prolyl 4-hydroxylase, a collagen synthesis enzyme, in serum or liver. Hochu-ekki-to showed a similar trend. Although Sho-saiko-to did not significantly suppress the increase in hepatic hydroxyproline, it intensely suppressed serum type IV collagen. Further, Hochu-ekki-to, Ninjin-youei-to, and Sho-saiko-to inhibited the production of fibrogenic cytokines, namely TGF-beta1 and IL-13, in the serum and liver. Additionally, we showed that IL-13 levels were positively correlated with hydroxyproline contents in the liver. These results suggest that Ninjin-youei-to as well as Hochu-ekki-to suppress porcine serum-induced liver fibrosis more effectively than Sho-saiko-to. The effects of these three medicines probably depend on the inhibition of fibrogenic cytokine production, resulting in the suppression of collagen synthesis and deposition in the liver, though different mechanisms underlie their anti-fibrogenic effects.

Modulation of urokinase-type plasminogen activator by transforming growth factor beta1 in acetaldehyde-activated hepatic stellate cells

The aim of this study was to determine whether transforming growth factor-beta1 (TGF-beta1) induces the synthesis, release and gene expression of urokinase-type plasminogen activator (uPA) in hepatic stellate cells. In addition to stimulating collagen production, TGF-beta1 induced the morphological and phenotypical changes characteristic of hepatic stellate cell activation. However, these changes accentuated in cells previously activated with acetaldehyde. TGF-beta1 increased to 2-fold uPA activity in lysates from quiescent cells, and to 3.5-fold in activated cells, and induced uPA gene expression to the same extent in both activated and non-activated cells. TGF-beta1 had a modest stimulatory action on the release of uPA into the conditioned medium, but reduced acetaldehyde-induced release, as demonstrated by Western blot analysis. In accord, whereas TGF-beta1 produces no effect on uPA activity in the conditioned media from quiescent cells, it significantly reduces the stimulatory action of acetaldehyde. These results show that the activity and gene expression of uPA are regulated by both acetaldehyde and TGF-beta1 and that the proteolytic activity in the extracellular space is reduced by the influence of TGF-beta1. Further studies on the molecular mechanisms responsible for the regulation of the plasminogen system by TGF-beta1 and other molecules in the presence of acetaldehyde will contribute to a better understanding of the processes involved in fibrogenesis.

Syndecan-1 up-regulated by ephrinB2/EphB4 plays dual roles in inflammatory angiogenesis

EphrinB2 and EphB4, its cognate receptor, are important in the vascular development of the mouse embryo. Their roles in human inflammatory angiogenesis, however, are not well understood. By examining hyperinflammatory lesions, we saw that ephrinB2 was predominantly expressed in macrophage-like cells and EphB4 in small venules. Because macrophages usually transmigrate through postcapillary venules during inflammation, we wanted to explore the downstream effects of EphB4 after binding to ephrinB2. By using cDNA microarray technique and following reverse transcriptase-polymerase chain reaction (RT-PCR), we found that syntenin and syndecan-1 were up-regulated in EphB4-positive endothelial cells dose dependently and time dependently after stimulation with preclustered ephrinB2. In vitro, ephrinB2 suppressed the angiogenic effects of basic fibroblast growth factor (bFGF) on EphB4-positive endothelial cells, partially due to syndecan-1's competition with fibroblast growth factor receptor (FGFR) for bFGF. However, ephrinB2 exhibited angiogenic effects in vivo, possibly due to an inflammation-associated enzyme-heparanase. The enzymes could convert the inhibitory effect of ephrinB2 on EphB4-positive endothelial cells to an activating effect by removing poorly sulfated side chains of up-regulated syndecan-1 ectodomain. Depending on the presence of heparanases, the roles of syndecan-1 may be opposite in different physiological settings.

Identification of transforming growth factors actively transcribed during the progress of liver fibrosis in biliary atresia

BACKGROUND/PURPOSE

Transforming growth factor-beta (TGF-beta) 1 and 2 and their receptors TbetaR-I, TbetaR-II, and TbetaR-III are powerful profibrogenic mediators in the body. Their expression has not been completely elucidated in the progress of liver fibrosis associated with biliary atresia (BA).

METHODS

The authors compared the cytokine expression in the liver of 3 patients with BA at Kasai's procedure (KP) and in 3 patients at liver transplantation (LT). Two liver samples from children with no liver disorders served as normal controls (CO). Real-time quantitative reverse transcriptase polymerase chain reaction (QRT-PCR) was used to confirm the findings of relative mRNA expression of TGF-beta1 and 2 and their receptors. An immunohistochemistry and an enzyme-linked immunoassay (ELISA) were used to localize the liver cells that express TGF-beta2 and to quantitate the protein expression among groups.

RESULTS

Compared with controls, both TGF-beta1 and TGF-beta2 mRNA expression increased in the liver during the progress of liver fibrosis in patients with KP and LT on the array. Only TGF-beta2 showed a significant increase in expression in LT compared with KP and CO (P =.001 for TGF-beta2 and P = 0.054 for TGF-beta1). Both TbetaR-I and TbetaR-II showed no significant change among groups; TbetaR-III decreased significantly in LT compared with CO (P =.011). TGF-beta2 immunostaining was mainly localized in the bile duct epithelium and was remarkably higher in LT in which the proliferating bile ductules and the hepatocytes contributed to the increase in immunostaining and possibly to significantly higher plasma TGF-beta2 protein levels in LT than in KP.

CONCLUSIONS

This study identified TGF-beta2 as the most actively transcribed TGF-beta gene during the progress of liver fibrosis in BA and found a reciprocal relationship of upregulation of TGF-beta2 with downregulation of TbetaR-III in LT.

Acetaldehyde stimulates the activation of latent transforming growth factor-beta1 and induces expression of the type II receptor of the cytokine in rat cultured hepatic stellate cells

Acetaldehyde, the major active metabolite of alcohol, induces the activation of hepatic stellate cells (HSC), leading to over-production of alpha1(I) collagen and ultimately causing hepatic fibrosis. The underlying mechanisms of this process remain largely unknown. Transforming growth factor-beta1 (TGF-beta1) is a potent inducer of alpha1(I) collagen production. Accumulating evidence has shown a potential role for TGF-beta1 in alcohol-induced hepatic fibrogenesis. The aims of this study were to determine the effect of acetaldehyde on TGF-beta signalling, to elucidate the underlying mechanisms as well as to evaluate its role in expression of alpha1(I) collagen gene in cultured HSC. It was hypothesized that acetaldehyde activated TGF-beta signalling by inducing the expression of elements in the TGF-beta signal transduction pathway, which might contribute to alpha1(I) collagen gene expression in cultured HSC. Initial results revealed that acetaldehyde activated TGF-beta signalling in cultured HSC. Additional studies demonstrated that acetaldehyde stimulated the secretion and activation of latent TGF-beta1, and induced the expression of the type II TGF-beta receptor (Tbeta-RII). Further experiments found cis - and trans -activating elements responsible for Tbeta-RII gene expression induced by acetaldehyde. Activation of TGF-beta signalling by acetaldehyde contributed to alpha1(I) collagen gene expression in cultured HSC. In summary, this report demonstrated that acetaldehyde stimulated TGF-beta signalling by increasing the secretion and activation of latent TGF-beta1 as well as by inducing the expression of Tbeta-RII in cultured HSC. Results from this report provided a novel insight into mechanisms by which acetaldehyde stimulated the expression of alpha1(I) collagen in HSC and a better understanding of effects of alcohol (or acetaldehyde) on hepatic fibrogenesis.

The antioxidant (-)-epigallocatechin-3-gallate inhibits activated hepatic stellate cell growth and suppresses acetaldehyde-induced gene expression

Activated hepatic stellate cells (HSC) are the primary source of excessive production of extracellular matrix during liver fibrogenesis. Although the underlying mechanisms remain incompletely understood, it is widely accepted that oxidative stress plays a critical role in liver fibrogenesis. Suppression of HSC growth and activation, as well as induction of apoptosis, have been proposed as therapeutic strategies for treatment and prevention of this disease. In the present report, we elucidated, for the first time, effects of the antioxidant (-)-epigallocatechin-3-gallate (EGCG), a major (and the most active) component of green tea extracts, on cultured HSC growth and activation. Our results revealed that EGCG significantly inhibited cultured HSC growth by inducing cell cycle arrest and apoptosis in a dose- and time-dependent manner. In addition, EGCG markedly suppressed the activation of cultured HSC as demonstrated by blocking transforming growth factor-beta signal transduction and by inhibiting the expression of alpha1(I) collagen, fibronectin and alpha-smooth muscle actin genes induced by acetaldehyde, the most active metabolite of ethanol. Furthermore, EGCG reacted differently in the inhibition of nuclear factor-kappaB activity between cultured HSC with or without acetaldehyde stimulation. Taken together, our results indicated that EGCG was a novel and effective inhibitor for activated HSC growth and activation in vitro. Further studies are necessary to evaluate the effect of this polyphenol in prevention of quiescent HSC activation in vivo, and to further elucidate the underlying mechanisms.

Quantitative analysis of transforming growth factor beta 1 mRNA in patients with alcoholic liver disease

AIM: To investigate the expression of the transforming growth factor beta 1 (TGF- beta 1) mRNA in different stages of alcoholic liver disease (ALD) and its clinical value.

METHODS: One hundred and seven male alcoholics were grouped by clinical findings into four groups: Alcohol abusers without liver impairment (n = 22), alcoholic steatosis (n = 30); alcoholic hepatitis (n = 31); and alcoholic cirrhosis (n = 24). Using peripheral blood mononuclear cells (PBMC) as samples the gene expression of TGF-beta 1 was examined quantitatively by reverse transcription polymerase chain reaction (RT-PCR) and dot blot. There are 34 healthy subjects served as control.

RESULTS: The expression of TGF-beta 1 from all ALD patients was significantly greater than that in controls (1.320 ± 1.162 vs 0.808 ± 0.276, P < 0.001). The differences of the expressions were significant between the patients from each groups (alcoholic steatosis, alcoholic hepatitis and alcoholic cirrhosis) and the controls (1.168 ± 0.852, 1.462 ± 1.657, 1.329 ± 0.610 vs 0.808 ± 0.276, P < 0.050). No significant differences of TGF-beta 1 mRNA expression were observed between alcohol abusers without liver impairment and controls. The expressions in patients with alcoholic hepatitis and alcoholic cirrhosis were significantly greater than that in alcohol abusers respectively (1.462 ± 1.657, 1.329 ± 0.610 vs 0.841 ± 0.706, P < 0.050). No significant differences of TGF-beta 1 mRNA expression were observed between alcoholic fatty liver men and alcohol abusers.

CONCLUSION: TGF-beta 1 expression level can be a risk factor for alcoholic liver disease and might be related to the inflammatory activity and fibrosis of the liver in patients.

Transforming growth factor-beta1 as a surrogate marker of hepatic dysfunction in chronic liver diseases

The aim of the study was to evaluate the possible association between plasma concentrations of transforming growth factor-beta1 (TGF-beta1) and the degree of hepatic dysfunction in patients with chronic liver diseases. TGF-beta1 was measured with an enzyme immunoassay in plasma from 21 patients with chronic active hepatitis and 40 patients with liver cirrhosis. Normal values were obtained from a group of 13 healthy volunteers. Results were analysed with respect to aetiology and the degree of liver insufficiency as evaluated by the Child-Pugh classification. The mean plasma concentration of TGF-beta1 in patients (36.9+/-2.8 ng/ml) was twice that found in normal volunteers (18.3+/-1.6 ng/ml). The highest values were observed in patients with alcoholic liver cirrhosis (44.4+/-4.7 ng/ml). Plasma TGF-beta1 showed a statistically significant positive correlation with the degree of liver insufficiency. These results indicate the possible use of plasma TGF-beta1 measurement as a good marker of liver function impairment. Further observation of patients involved in this study may help to evaluate its possible prognostic value in chronic liver diseases.

Circulating transforming growth factor beta(1) as an indicator of hepatic function impairment in liver cirrhosis

In the liver, transforming growth factor (TGF) -beta(1)is primarily responsible for activation of fat-storing cells, which are the main source of extracellular matrix proteins. Their deposition play a key role in the development of liver cirrhosis. The aim of this study was to evaluate plasma TGF-beta(1)in patients with different stages of liver cirrhosis and its possible use as an indicator of liver function impairment. TGF-beta(1)was measured in the plasma of 40 patients with liver cirrhosis. To estimate possible effect of liver insufficiency on plasma TGF-beta(1), patients were divided into three groups: A, B and C, univocal with Child-Pugh classes. Normal values were collected from 13 healthy volunteers. Liver cirrhosis resulted in a significant increase of plasma concentration of TGF-beta(1)(39.3+/-3.8 ng/ml), which doubled normal values (18.3+/-1.6 ng/ml). The highest concentrations were observed in alcoholic patients (44.4+/-4.7 ng/ml). TGF-beta(1)level increased depending on the degree of liver insufficiency, demonstrated by a significant positive correlation with Child-Pugh score (r=0.591). Values in group A were similar to normal, but were significantly elevated in groups B and C. These findings suggest possible use of plasma TGF-beta(1)measurement as an indicator of liver function impairment and possible marker of hepatic fibrosis progression in cirrhotic patients.

Keratinocytes suppress transforming growth factor-beta1 expression by fibroblasts in cultured skin substitutes

Transforming growth factor (TGF)-beta1 is a multipotent growth factor with an important role in tissue homeostasis. This growth factor regulates cell proliferation, adhesion, migration and differentiation, as well as extracellular matrix deposition. The temporal secretion and activation of latent TGF-beta1 is thus of major importance to physiological and pathological processes and in wound healing and tumour formation. Cultured skin substitutes, as used to treat extensive acute or chronic skin wounds, offer an attractive model to investigate cellular interactions in cytokine and growth factor expression and response in vitro. In the present investigation, expression of TGF-beta1 was analysed in keratinocyte, fibroblast and melanocyte monolayer cultures, as well as in the dermal vs. epidermal components of reconstituted human skin. Immunohistology, enzyme-linked immunosorbent assay (ELISA) and Northern blotting were used to demonstrate expression at the RNA and protein level. In the monolayer cultures, levels of TGF-beta1 synthesized by melanocytes were observed to be considerably elevated when compared with keratinocytes. Most TGF-beta1, however, was secreted by fibroblasts. The relative contribution of the epidermal and dermal components of the skin substitutes to overall TGF-beta1 levels was determined by comparing results obtained for either component in the presence and absence of fibroblasts and keratinocytes. From results obtained by ELISA it was apparent that TGF-beta1 levels generated predominantly by fibroblasts within the skin substitutes were greatly reduced over time in the presence of keratinocytes. Suppression of fibroblast TGF-beta1 expression in the presence of keratinocytes was also demonstrable at the RNA level by Northern blotting. Results obtained by immunohistochemistry suggest that most, if not all, of the growth factor was present in the latent form. It is therefore most likely that the observed effect results from a factor secreted by keratinocytes, which is capable of suppressing TGF-beta1 synthesis by fibroblasts. These results suggest that expression of TGF-beta1 by fibroblasts is downregulated by paracrine actions of keratinocytes in healing skin.