Transforming growth factor-beta 1 in chronic hepatitis C

Immunohistochemical localization of transforming growth factor β-1 and its relationship with collagen expression in advanced liver fibrosis due to biliary atresia

PURPOSE

Biliary atresia (BA) is the most common indication of liver transplantation in children. Pathogenesis of hepatic fibrosis, which is a prominent feature of BA, remains obscure. The purpose of this work was to determine the cellular sources of transforming growth factor beta-1 (TGFβ1) and establish the relationship between TGFβ1-producing cells and extracellular matrix producing myofibroblasts (MFBs) in advanced BA.

METHODS

Trichrome staining and immunohistochemistry were carried out to determine the expression pattern of collagen and TGFβ1 protein in explant liver specimens from patients with BA. The intensities of portal and lobular TGFβ1 expressions were compared. Immunofluorescence technique was carried out to determine the relationship between α-smooth muscle actin (α-SMA)-positive-MFB and TGFβ1-positve cells.

RESULTS

Lobular TGFβ1 protein expression was significantly higher than portal (89 ± 6 versus 10 ± 1 arbitrary units, P ≤ 0.05), whereas no difference was noted in livers used as control (10 ± 1.6 versus 19 ± 5 arbitrary units, P = 0.11). TGFβ1 expression was more in the center of nodules versus MFB in surrounding fibrous septa. Contrary to TGFβ1 expression, α1-SMA was mostly expressed in the portal structures and the adjacent fibrous septa enacting lobulation of the parenchyma. The results obtained by coimmunofluorescence staining showed no colocalization of α-SMA and TGFβ1.

CONCLUSIONS

TGFβ1 protein expression is mostly localized to hepatocytes in advanced BA. These findings suggest a paracrine mechanisms of TGFβ1-driven fibrogenesis in advanced BA.

Non-invasive assessment of liver fibrosis: it is time for laboratory medicine

Chronic liver diseases (CLDs) represent a major cause of morbidity and mortality worldwide. In all etiologies of CLDs, staging of liver fibrosis is essential for both prognosis and management. Until a few years ago, liver biopsy was the only tool for the diagnosis of liver fibrosis in patients with CLDs. However, liver biopsy is an invasive and costly procedure. More recently, various serum biomarkers and laboratory tests have been proposed as surrogates of liver histology. Due to inadequate diagnostic accuracy or to lack of sufficient validation, guidelines still do not recommend them as a substitute for liver biopsy that is still considered the gold standard for the diagnosis of liver fibrosis. Notably, non-invasive serum biomarkers, when combined, may reduce by 50%-80% the number of liver biopsies needed for correctly classifying hepatic fibrosis. However, liver biopsy cannot be avoided completely, but should be used in those cases in which non-invasive methods show poor accuracy. In this view, serum biomarkers and liver biopsy represent a union between laboratory medicine and hepatology.

SERPINB3 modulates TGF-beta expression in chronic liver disease

Transforming growth factor-beta1 (TGF-beta1) is the master cytokine in the pathogenesis of liver fibrosis. TGF-beta1 and extent of fibrosis were correlated recently to the serpin SERPINB3 in idiopathic pulmonary fibrosis, a chronic disease recalling liver cirrhosis. The aim of this study was to assess the relation between SERPINB3, TGF-beta1 and fibrosis in chronic liver diseases and to determine the effect of this serpin on TGF-beta1 expression using in vitro models. SERPINB3 and TGF-beta1 were evaluated in liver biopsies of 94 patients with chronic liver disease. The effect of SERPINB3 on TGF-beta1 expression was determined in primary human hepatocytes, HepG2 and Huh7 cells transfected with intact SERPINB3 human gene or with reactive site loop deleted mutants. A significant correlation between TGF-beta1 and SERPINB3 at the protein level was observed in liver biopsies, confirmed by a positive correlation at mRNA level. Both proteins were correlated to the extent of liver fibrosis. All transfected cells showed increased TGF-beta1 mRNA and protein production and the integrity of the reactive site loop of the serpin was crucial to achieve this effect. In conclusion, chronically damaged hepatocytes produce SERPINB3 and TGF-beta, and the anti-protease activity of this serpin might be implicated in TGF-beta1 induction.

Hepatocyte NAD(P)H oxidases as an endogenous source of reactive oxygen species during hepatitis C virus infection

Oxidative stress has been identified as a key mechanism of hepatitis C virus (HCV)-induced pathogenesis. Studies have suggested that HCV increases the generation of hydroxyl radical and peroxynitrite close to the cell nucleus, inflicting DNA damage, but the source of reactive oxygen species (ROS) remains incompletely characterized. We hypothesized that HCV increases the generation of superoxide and hydrogen peroxide close to the hepatocyte nucleus and that this source of ROS is reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase 4 (Nox4). Huh7 human hepatoma cells and telomerase-reconstituted primary human hepatocytes, transfected or infected with virus-producing HCV strains of genotypes 2a and 1b, were examined for messenger RNA (mRNA), protein, and subcellular localization of Nox proteins along with the human liver. We found that genotype 2a HCV induced persistent elevations of Nox1 and Nox4 mRNA and proteins in Huh7 cells. HCV genotype 1b likewise elevated the levels of Nox1 and Nox4 in telomerase-reconstituted primary human hepatocytes. Furthermore, Nox1 and Nox4 proteins were increased in HCV-infected human liver versus uninfected liver samples. Unlike Nox1, Nox4 was prominent in the nuclear compartment of these cells as well as the human liver, particularly in the presence of HCV. HCV-induced ROS and nuclear nitrotyrosine could be decreased with small interfering RNAs to Nox1 and Nox4. Finally, HCV increased the level of transforming growth factor beta 1 (TGFbeta1). TGFbeta1 could elevate Nox4 expression in the presence of infectious HCV, and HCV increased Nox4 at least in part through TGFbeta1.

CONCLUSION

HCV induced a persistent elevation of Nox1 and Nox4 and increased nuclear localization of Nox4 in hepatocytes in vitro and in the human liver. Hepatocyte Nox proteins are likely to act as a persistent, endogenous source of ROS during HCV-induced pathogenesis.

Natural killer cells: versatile roles in autoimmune and infectious diseases

Natural killer (NK) cells are essential members of innate immunity and they rapidly respond to a variety of insults via cytokine secretion and cytolytic activity. Effector functions of NK cells form an important first line of innate immunity against viral, bacterial and parasitic infections, as well as an important bridge for the activation of adaptive immune responses. The control of NK-cell activation and killing is now understood to be a highly complex system of diverse inhibitory and activatory receptor-ligand interactions, sensing changes in MHC expression. NK cells have a functional role in innate immunity as the primary source of NK-cell-derived immunoregulatory cytokines, which have been identified in target organs of patients suffering from autoimmune diseases, and play a critical role in early defense against infectious agents. This review focuses on recent research of NK cells, summarizing their potential immunoregulatory role in modulating autoimmunity and infectious diseases.

Characterization of the cellular immune response in hepatitis C virus infection

Hepatitis C virus (HCV), a hepatotropic RNA virus, is a major causative agent of chronic hepatitis, liver cirrhosis, and hepatocellular carcinomas. The host immune responses, especially cellular immune responses, play an important role in viral clearance, liver injury, and persistent HCV infection. A thorough characterization of the HCV cellular immune responses is important for understanding the interplays between host immune system and viral components, as well as for developing effective therapeutic and prophylactic HCV vaccines. Recent advances that provide better understanding the cell immune responses in HCV infection are summarized in this article.

Peptide inhibitors of transforming growth factor-beta enhance the efficacy of antitumor immunotherapy

Transforming growth factor-beta (TGF-beta) is a cytokine with potent immunosuppressive effects and is overexpressed in many tumors. Therefore, development of molecules able to inhibit TGF-beta is of paramount importance to improve the efficacy of antitumor immunotherapy. TGF-beta inhibitor peptides P144 and P17 were combined with the administration of adjuvant molecules poly(I:C) and agonistic anti-CD40 antibodies, and their effect on the growth of E.G7-OVA established tumors and on antitumor immune response was evaluated. Tumor rejection efficacy of a single administration of adjuvants was enhanced from 15 to 70 % when combined with repeated injections of TGF-beta inhibitor peptides. Simultaneous administration of adjuvants and TGF-beta inhibitor peptides was required for maximal therapeutic efficacy. Although tumor cells produced TGF-beta, it was found that the beneficial effect of peptide administration was mainly due to the inhibition of TGF-beta produced by regulatory CD4(+)CD25(+) T cells rather than by tumor cells. The enhanced antitumor effect was accompanied by a higher activity of dendritic cells, natural killer cells and tumor antigen-specific T cells, as well as by a decrease in the number of myeloid-derived suppressor cells. In conclusion, administration of peptide inhibitors of TGF-beta in therapeutic vaccination enhances the efficacy of immunotherapy by increasing antitumor immune responses. These peptide inhibitors may have important applications for current immunotherapeutic strategies.

Hepatitis C virus-induced hepatocarcinogenesis

Although there is strong evidence that hepatitis C virus (HCV) is one of the leading causes of hepatocellular carcinoma (HCC), there is still much to understand regarding the mechanism of HCV-induced transformation. While liver fibrosis resulting from long-lasting chronic inflammation and liver regeneration resulting from immune-mediated cell death are likely factors that contribute to the development of HCC, the direct role of HCV proteins remains to be determined. In vitro studies have shown that HCV expression may interfere with cellular functions that are important for cell differentiation and cell growth. However, most studies were performed in artificial models which can only give clues for potential mechanisms that need to be confirmed in more relevant models. Furthermore, the difficulty to identify HCV proteins and infected liver cells in patients, contributes to the complexity of our current understanding. For these reasons, there is currently very little experimental evidence for a direct oncogenic role of HCV. Further studies are warranted to clarify these issues.

FOXP3 expression in hepatitis C virus-specific CD4+ T cells during acute hepatitis C

BACKGROUND & AIMS

Down-regulation of hepatitis C virus (HCV)-specific CD4(+) T-cell responses is a hallmark of chronic viral persistence in acute hepatitis C. FOXP3(+)CD25(+)CD4(+) regulatory T cells can modulate HCV-specific immune responses in vitro, but the role of virus-specific regulatory T cells in the pathogenesis of chronic viral persistence is unknown.

METHODS

Two novel HLA-DR15 tetramers were synthesized to study the kinetics and phenotype of FOXP3(+)-expressing HCV-specific CD4(+) T cells from 10 patients with acute hepatitis C and 15 patients with chronic hepatitis C.

RESULTS

In acute hepatitis C, generally only a low percentage of HCV-specific CD4(+) T cells expressed FOXP3(+) (mean of 2.5% in patients with self-limited acute hepatitis C vs 2.4% in patients with evolving chronic hepatitis C). Although distinct but short-lived increases in virus-specific FOXP3(+)CD4(+) T cells occurred in 3 patients (30%, 26%, and 7% of tet(+) CD4(+) T cells, respectively), these did not correlate with the evolution of chronic hepatitis C. HCV-specific FOXP3(+)CD4(+) T cells displayed a distinct phenotype, with only 10% expressing CD25 and 40% being CD127low. Interestingly, this phenotype of FOXP3(+)CD4(+) T cells was already expanded in bulk CD4(+) T cells in patients with chronic hepatitis C.

CONCLUSIONS

Although short-lived increases in HCV-specific FOXP3(+)CD4(+) T cells occur during the course of acute hepatitis C, we could not demonstrate an association of HCV-specific regulatory T cells and persistent viremia.

Validation of connective tissue growth factor (CTGF/CCN2) and its gene polymorphisms as noninvasive biomarkers for the assessment of liver fibrosis

Clinical and experimental studies have demonstrated that connective-tissue growth factor (CTGF) expression is increased in fibrotic human liver and experimental animal models of liver fibrogenesis. CTGF has been linked to transforming growth factor-beta (TGF-beta) pathways in fibroproliferative diseases and specific polymorphisms within the CTGF gene may predispose for fibrosis in systemic sclerosis. As CTGF is detectable in various human fluids (serum, plasma and urine), it may provide information about fibrotic remodelling processes and reflect hepatic TGF-beta bioactivity. We established a novel ELISA for the measurement of serum CTGF and tested its clinical value in patients with chronic hepatitis C virus (HCV) infection and chronic liver disease (CLD). HCV infected patients (n = 138) had significantly higher serum CTGF levels than healthy controls. CTGF was linked to the histological degree of liver fibrosis. To expand the results to other aetiologies, a separate cohort of CLD patients (n = 129) was evaluated, showing higher serum CTGF than healthy controls and again an association with advanced stages of liver cirrhosis (Child B and C). Although independent of the underlying aetiology, serum CTGF was most powerful in indicating fibrosis/advanced disease states in HCV-related disorders. The genotyping of six polymorphisms (rs6917644, rs9399005, rs6918698, rs9493150, rs2151532 and rs11966728) covering the CTGF locus in 365 patients suffering from chronic hepatitis C revealed that none of these polymorphisms showed a genotypic or allelic association with the severity of hepatic fibrosis. Taken together, serum CTGF is suitable for determination of hepatic fibrosis and most powerful in patients with chronic HCV infection.

Hyaluronic acid, transforming growth factor-beta1 and hepatic fibrosis in patients with chronic hepatitis C virus and human immunodeficiency virus co-infection

Chronic hepatitis C virus (HCV) infection follows an accelerated course in patients co-infected with human immunodeficiency virus (HIV); establishing the extent of liver fibrosis is crucial for disease staging and determining treatment strategy in these patients. The utility of noninvasive markers of fibrosis as alternatives to liver biopsy has not been well-studied in these patients. We evaluated the predictive value of serum transforming growth factor-beta1 (TGF-beta1) and hyaluronic acid (HA) levels for determining the extent of liver fibrosis. Liver biopsies and blood samples were collected from 69 consecutive patients (74% male; median age, 41 years) between May 2005 and November 2006. Serum TGF-beta1 and HA were analysed using commercial kits. Aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transpeptidase levels were elevated in 81%, 70% and 60% of patients, respectively. Fifty-three patients (90%) were on highly active antiretroviral therapy and the median CD4-positive cell count was 422 cells/microL. The extent of fibrosis according to Scheuer's scoring was 32% F0 (no fibrosis), 16.5% F1, 16.5% F2, 26% F3 and 7% F4 (cirrhosis). Mean serum TGF-beta1 was 36.1 +/- 14.4 ng/mL; mean serum HA was 75.2 +/- 85.0 microg/L. Serum HA was positively associated and significantly correlated with the stage of fibrosis (r = 0.56; P < 0.05). The area under the curve for discriminating mild (F0-F2) from significant (F3-F4) fibrosis in receiver operating analysis using HA was 0.83 (sensitivity, 87%; specificity, 70%). These data suggest that HA is clinically useful for predicting liver fibrosis and cirrhosis in patients co-infected with HCV/HIV. However, serum TGF-beta1 was not predictive of histological damage in co-infected individuals treated with HAART.

The essential roles of TGFB1 in reproduction

Transforming growth factor beta 1 (TGFB1) is implicated as a key regulator of the development and cyclic remodelling characteristic of reproductive tissues. The physiological significance of TGFB1 in reproductive biology and fertility has been extensively examined in Tgfb1 null mutant mice. Genetic deficiency in TGFB1 causes perturbed functioning of the hypothalamic-pituitary-gonadal axis, inhibiting luteinising hormone (LH) synthesis and leading to downstream effects on testosterone production in males and estrous cycle abnormalities in females. Oocyte developmental incompetence, accompanied by early embryo arrest as well as altered pubertal mammary gland morphogenesis are observed. In addition to LH and testosterone deficiency, male Tgfb1 null mice demonstrate complete inability to mate with females, associated with failure to initiate and/or sustain successful penile intromission or ejaculation. These studies demonstrate the profound significance of TGFB1 in male and female reproductive physiology, and provide a foundation for exploring the significance of this cytokine in human infertility and sexual dysfunction.

Genomic analysis reveals a potential role for cell cycle perturbation in HCV-mediated apoptosis of cultured hepatocytes

The mechanisms of liver injury associated with chronic HCV infection, as well as the individual roles of both viral and host factors, are not clearly defined. However, it is becoming increasingly clear that direct cytopathic effects, in addition to immune-mediated processes, play an important role in liver injury. Gene expression profiling during multiple time-points of acute HCV infection of cultured Huh-7.5 cells was performed to gain insight into the cellular mechanism of HCV-associated cytopathic effect. Maximal induction of cell-death-related genes and appearance of activated caspase-3 in HCV-infected cells coincided with peak viral replication, suggesting a link between viral load and apoptosis. Gene ontology analysis revealed that many of the cell-death genes function to induce apoptosis in response to cell cycle arrest. Labeling of dividing cells in culture followed by flow cytometry also demonstrated the presence of significantly fewer cells in S-phase in HCV-infected relative to mock cultures, suggesting HCV infection is associated with delayed cell cycle progression. Regulation of numerous genes involved in anti-oxidative stress response and TGF-beta1 signaling suggest these as possible causes of delayed cell cycle progression. Significantly, a subset of cell-death genes regulated during in vitro HCV infection was similarly regulated specifically in liver tissue from a cohort of HCV-infected liver transplant patients with rapidly progressive fibrosis. Collectively, these data suggest that HCV mediates direct cytopathic effects through deregulation of the cell cycle and that this process may contribute to liver disease progression. This in vitro system could be utilized to further define the cellular mechanism of this perturbation.

Differential expression of the CXCR3 ligands in chronic hepatitis C virus (HCV) infection and their modulation by HCV in vitro

To investigate chemokine expression networks in chronic hepatitis C virus (HCV) infection, we used microarray analysis to determine chemokine expression in human infection and in chimpanzees experimentally infected with HCV. The CXCR3 chemokine family was highly expressed in both human and chimpanzee infection. CXCL10 was the only CXCR3 chemokine elevated in the serum, suggesting that it may neutralize any CXCR3 chemokine gradient established between the periphery and liver by CXCL11 and CXCL9. Thus, CXCR3 chemokines may not be responsible for recruitment of T lymphocytes but may play a role in positioning these cells within the liver. The importance of the CXCR3 chemokines, in particular CXCL11, was highlighted by replicating HCV (JFH-1) to selectively upregulate its expression in response to gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha). This selective upregulation was confirmed at the transcriptional level by using the CXCL11 promoter driving the luciferase reporter gene. This synergistic increase in expression was not a result of HCV protein expression but the nonspecific innate response to double-stranded RNA (dsRNA), as both in vitro-transcribed HCV RNA and the dsRNA analogue poly(I:C) increased CXCL11 expression and promoter activity. Furthermore, we show that CXCL11 is an IRF3 (interferon regulatory factor 3) response gene whose expression is selectively enhanced by IFN-gamma and TNF-alpha. In conclusion, the CXCR3 chemokines are the most significantly expressed chemokines in chronic hepatitis C and most likely play a role in positioning T cells in the liver. Furthermore, HCV can selectively increase CXCL11 expression in response to IFN-gamma and TNF-alpha stimulation that may play a role in the pathogenesis of HCV-related liver disease.

Role of Kupffer cells in hepatic fibrosis

Kupffer cells (KC), a kind of nonparenchymal cells and defenders in the liver, release various chemical mediators to induce liver injury, and play an important role in many pathologic changes of the liver. Hepatic fibrosis is the common pathologic process of varied chronic liver diseases, and it is also a "transfer station" for many chronic liver diseases lapsing to cirrhosis. As important influencing factors, cytokines secreted by KC are involved in the occurrence and progression of hepatic fibrosis. Therefore, lucubrating the role and mechanism of KC in the progression of hepatic fibrosis, and investigating the KC-related therapeutic strategies of anti-fibrosis have practical significances for the prevention and treatment of liver injury and the raise of patients' survival rates in clinical practice.

Identification and in vitro expansion of functional antigen-specific CD25+ FoxP3+ regulatory T cells in hepatitis C virus infection

CD4(+)CD25(+) regulatory T cells (CD25(+) Tregs) play a key role in immune regulation. Since hepatitis C virus (HCV) persists with increased circulating CD4(+)CD25(+) T cells and virus-specific effector T-cell dysfunction, we asked if CD4(+)CD25(+) T cells in HCV-infected individuals are similar to natural Tregs in uninfected individuals and if they include HCV-specific Tregs using the specific Treg marker FoxP3 at the single-cell level. We report that HCV-infected patients display increased circulating FoxP3(+) Tregs that are phenotypically and functionally indistinguishable from FoxP3(+) Tregs in uninfected subjects. Furthermore, HCV-specific FoxP3(+) Tregs were detected in HCV-seropositive persons with antigen-specific expansion, major histocompatibility complex class II/peptide tetramer binding affinity, and preferential suppression of HCV-specific CD8 T cells. Transforming growth factor beta contributed to antigen-specific Treg expansion in vitro, suggesting that it may contribute to antigen-specific Treg expansion in vivo. Interestingly, FoxP3 expression was also detected in influenza virus-specific CD4 T cells. In conclusion, functionally active and virus-specific FoxP3(+) Tregs are induced in HCV infection, thus providing targeted immune regulation in vivo. Detection of FoxP3 expression in non-HCV-specific CD4 T cells suggests that immune regulation through antigen-specific Treg induction extends beyond HCV.

Diagnosis and quantitation of fibrosis

Hepatic fibrosis is the final common pathway for many different liver insults. Originally considered to be irreversible, hepatic fibrosis is now known to be a dynamic process with a significant potential for resolution. The diagnosis and quantitation of fibrosis have traditionally relied on liver biopsy. However, there are a number of drawbacks including the invasive nature of the procedure, sampling error, and interobserver variability. This article reviews the current role of liver biopsy in the assessment of hepatic fibrosis and discusses the role of the newer noninvasive methods including serum markers and radiologic tests.

Tacrolimus and cyclosporin doses and blood levels in hepatitis C and alcoholic liver disease patients after liver transplantation

Hepatitis C virus (HCV)-induced cirrhosis is the most common indication for liver transplantation (LT). However, graft reinfection is nearly universal. The choice of immunosuppression, including the calcineurin inhibitor (CNI), may have some effect on severity of recurrence and graft survival. In addition, HCV recurrence may have some impact on metabolism of immunosuppressive drugs. In this retrospective study, we examined the dose and blood levels of tacrolimus (TAC) and cyclosporin A (CYA) in HCV patients consecutively undergoing transplantation (TAC, n = 44; CYA, n = 60) and surviving 12 months post-LT. In addition, we examined the CNI dose and blood levels in an age- and gender-matched comparison group of patients who were transplanted for alcoholic liver disease (ALD) (TAC, n = 44; CYA, n = 47). During the 12-month period of observation, TAC levels were significantly higher for HCV than for ALD patients (P = 0.002). The dose of TAC decreased over time for both HCV and ALD patients (P < 0.001), but the reduction was greater for HCV patients (P = 0.03). CYA dose decreased over time for both groups (P < 0.001) but a greater reduction was observed for the HCV group (P = 0.007). For both HCV and ALD patients, CYA levels decreased over time (P < 0.001) but there was no significant difference between HCV and ALD patients. Thus, to maintain comparable blood levels, a greater reduction of dose was required for HCV than for ALD patients. In conclusion, our observations demonstrate a likely effect of HCV infection on CNI metabolism, an effect that is not clearly due to graft damage. Physicians need to be alert to this interaction and to the need to respond quickly to changes in CNI levels that may be associated with HCV infection and with HCV clearance during antiviral therapy.

Cytokines and chronic liver disease

From an immunological point of view, the healthy liver has been usually associated with the phenomenon of tolerance. A microenvironment of regulatory cytokines produced by liver Kuppfer cells and liver sinusoidal endothelial cells has contributed, together with resident dendritic cells, to generate a tolerogenic environment in this tissue. In this review we discussed the intrahepatic responses to different sorts of liver injury, such as hepatotrophic viruses, alcohol or putative self-antigens. In each case we analyzed the impact of different cytokines in the clinical outcome of the different pathological situations.

Polymorphism of interferon-gamma gene at position +874 and clinical characteristics of chronic hepatitis C

A T-to-A polymorphic sequence at position +874 in the interferon (IFN)-gamma gene (+874 IFN-gamma) might be associated with disease susceptibilities. To investigate the influence of +874 IFN-gamma polymorphism on the hepatitis C virus (HCV) viral load and the severity of liver disease, the single nucleotide polymorphism (SNP) was determined in 302 histologically proved chronic hepatitis C (CHC) patients [M/F: 180/122, mean age: 48.8 +/- 11.6 years, HCV genotype 1b: 147 (48.7%), liver cirrhosis: 29 (9.6%)] by using a polymerase chain reaction-sequence specific primers (PCR-SSP) approach. The distribution of genotypes for +874 IFN-gamma were T/T: 12 (4.0%), T/A: 71 (23.5%), and A/A: 219 (72.5%) and 27.5% (83/302) of patients' inherited T allele. The mean age of patients without A allele was significantly lower than other patients (41.7 +/- 11.3 vs 49.2 +/- 11.5 years, P = 0.028). Patients with the T allele of +874 IFN-gamma had a significantly higher rate of liver cirrhosis than patients with homozygote A allele (15.7% vs 7.3%, P = 0.028). By multivariate logistic regression analyses, T allele of +874 IFN-gamma and age were independent factors associated with cirrhosis (odds ratio/95% confidence interval: 2.519/1.128-5.622 and 1.065 /1.025-1.107, respectively). In conclusion, the authors' findings indicate that inheritance of +847 IFN-gamma polymorphism is associated with the cirrhosis in patients with CHC.

Effects of interferon plus ribavirin treatment on NF-kappaB, TGF-beta1, and metalloproteinase activity in chronic hepatitis C

Little is known about the cellular and molecular mechanisms underlying the effects of anti-viral therapy on the regression of liver inflammation and fibrosis in chronic hepatitis C. The aim of this study was to evaluate the effects of interferon alpha and ribavirin in combination therapy on the tissue expression of nuclear-factor kB (NF-kappaB) (a transcription factor coordinating the expression of stress genes involved in immune response and inflammation), of the polypeptide transforming growth factor beta-1 (TGF-beta1) and matrix metalloproteinases 1 (MMP-1) (both of which play an important part in the pathological process of liver fibrogenesis), and on the serum levels of soluble TGF-beta1, tissue inhibitors of metalloproteinases (TIMP)-1, and active endogenous MMP-2 and MMP-9 in paired (pre- and post-treatment) liver biopsy and serum samples of subjects with chronic hepatitis C. Serum levels of TGF-beta1, TIMP-1, MMP-2, and MMP-9 were evaluated by enzyme-linked immunosorbent assay. Liver expression of muscle-specific alpha-actin, NF-kappaB, TGF-beta1, and MMP-1 was studied immunohistochemically using commercially available mono- and polyclonal antisera in an avidin-biotin complex method. Combination therapy induced a reduction in the liver expression of TGF-beta and NF-kappaB and an increased expression of MMP-1, regardless of the virological response to the treatment. The greater expression of MMP-1 and lesser expression of NF-kappaB were both associated with an improvement in fibrosis score. These effects paralleled the significant increase in soluble MMP-9/TIMP-1 ratio in post-therapy sera. Combination therapy with interferon and ribavirin affects the tissue expression of TGF-beta-1 and NF-kappaB and favors metalloproteinase activity, and may thereby modulate hepatic fibrogenetic events.

Viral hepatitis and liver cancer: the case of hepatitis C

Chronic infection with the hepatitis C virus (HCV) is a major risk factor for the development of hepatocellular carcinoma (HCC) worldwide. The pathogenesis of HCC in HCV infection has extensively been analysed. Hepatitis C virus-induced chronic inflammation and the effects of cytokines in the development of fibrosis and liver cell proliferation are considered as one of the major pathogenic mechanisms. Increasing experimental evidence suggests that HCV contributes to HCC by directly modulating pathways that promote the malignant transformation of hepatocytes. Hepatitis C virus is an RNA virus that does not integrate into the host genome but HCV proteins interact with many host-cell factors well beyond their roles in the viral life cycle and are involved in a wide range of activities, including cell signaling, transcription, cell proliferation, apoptosis, membrane rearrangements, vesicular trafficking and translational regulation. At least four of the HCV gene products, namely HCV core, NS3, NS4B and NS5A, have been shown to exhibit transformation potential in tissue culture and several potentially oncogenic pathways have been shown to be altered by the expression of HCV proteins. Both HCV core and NS5A induce the accumulation of wild-type beta-catenin and the Wnt-beta-catenin pathway emerges as a common target for HCV (and HBV) in human HCCs, also independently from axin/beta-catenin gene mutations. Induction of both endoplasmic reticulum stress and oxidative stress by HCV proteins might also contribute to HCV transformation. Most of the putative transforming functions of the HCV proteins have been defined in artificial cellular systems, which may not be applicable to HCV infection in vivo, and still need to be established in relevant infection and disease models.

[Serum markers of non-invasive fibrosis in chronic hepatitis C virus infection]

MATTER: Liver biopsy is recommended for the management of patients infected by hepatitis C virus (HCV) and is currently the gold standard in assessing liver histology. It's an invasive test prone to complications with a morbidity rate of 0.3 to 0.6% and a mortality rate up to 0.05%. Since the last decade, researchers developed non invasifs biomarkers of liver fibrosis as an alternative to liver biopsy. These scores are based on different algorithms with various combinations of biomarkers issued from extra-cellular matrix, serum and cells.

CURRENT EVENTS

The diagnostic performance of these scores, estimated by the AUROC for significant fibrosis (>F2), in patients with chronic hepatitis C reach 0.78 to 0.90 for the most accurate. In HIV-HCV co-infected patients and patients with hepatitis C cirrhosis the diagnostic performance of these scores reach 0.74 to 0.88 and 0.73 to 0.97 respectively.

PERSPECTIVES

Liver fibrosis biomarkers constitutes an alternative to liver biopsy due to their non invasive approach, their easy reproducibility and accuracy. However, these scores must be used only after a validation in multicentric independent studies. The future is based on the comparison and validation of these scores after laboratory methods standardization.

Expression of Ki-67, transforming growth factor beta1, and B-cell lymphoma-leukemia-2 in liver tissue of patients with chronic liver diseases

BACKGROUND

The purpose of the present paper was to assess expression of proliferation, fibrosis and apoptosis markers in different phases of chronic liver diseases.

METHODS

Sixty-six adults with chronic liver diseases (chronic hepatitis C, n = 48; chronic hepatitis B, n = 10; alcohol chronic liver disease, n = 8) treated at the Department of Infectious Diseases and Hepatology from 1999 to 2001, composed the study group. Liver biopsy specimens were used for immunohistochemical assessment of expression of Ki-67, transforming growth factor beta1 (TGF-beta1) and B-cell lymphoma-leukemia-2 (Bcl-2). Grade of liver inflammation and stage of fibrosis were evaluated according to the Scheuer scale.

RESULTS

Expression of Ki-67 in hepatocytes was most intensive in patients with grade 2 and 3 inflammation. The expression in patients with grade 4 inflammation was low. The expression of Ki-67 in lymphocytes was most intensive in patients with grade 2 inflammation. Expression of TGF-beta1 in hepatocytes reached a maximum in patients with grade 2 or 3 inflammation and dropped in patients with grade 4 inflammation. There was a statistically significant correlation between stage of fibrosis and expression of TGF-beta1 in liver stromal cells. A very strong correlation was found between the expression of Bcl-2 in bile ductules epithelium and the grade of inflammation (P = 0.006). The expression of Bcl-2 in hepatocytes was observed only in patients with very intense liver inflammation (grade 3) and in patients with stage 3 or 4 fibrosis.

CONCLUSION

Processes of proliferation, fibrosis and apoptosis are not directly correlated to progression of liver disease. Expression of studied markers can be used for analysis of dynamics of these processes.

Natural killer cells: primary target for hepatitis C virus immune evasion strategies?

Liver cirrhosis and hepatocellular carcinoma secondary to chronic hepatitis C virus (HCV) infection requiring transplantation represents a significant public health problem. The most remarkable feature of hepatitis C virus is the ability to establish chronic infection in the vast majority of cases. Efforts to define clinical correlates of HCV persistence have focused primarily on CD4 and CD8 T cell responses. Until recently, the role of innate immunity in determining the outcome of HCV infection had received relatively little attention. Natural killer (NK) cells are an important antiviral effector population eliminating virus through direct killing and cytokine production. Recent studies highlighting the cross-talk between NK cells, dendritic cells (DCs) and T cells have prompted reevaluation of the important role NK cells play in regulating and maintaining specific immune responses. Like many other viruses, HCV has evolved strategies to evade detection and elimination by NK cells. T cell defects observed in HCV infection may be a consequence of inhibition of NK:DC interactions. We propose a theoretical model for HCV persistence that places the NK cell at the center of HCV immune evasion strategies. While this model is only theoretical, it provides a plausible interpretation of many published observations and a useful working model to test the role of NK cells in HCV persistence. In conclusion, the role of innate immune cells and their regulation of antigen-specific responses by the initial innate response to the virus, in particular NK cells, may prove to be an informative and clinically relevant avenue of investigation.

Effect of interferon alpha and ribavirin treatment on serum levels of transforming growth factor-β1, vascular endothelial growth factor, and basic fibroblast growth factor in patients with chronic hepatitis C

AIM: To assess the role of transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in the pathogenesis of fibrosis associated with chronic hepatitis C (CHC) and to evaluate the influence of the antiviral therapy on above parameter levels depending on the treatment results (complete response or no response).

METHODS: Study group included 100 patients with CHC, in whom fibrosis in liver specimens was assessed (Scheuer fibrosis score: 1-4 points). Control group included 30 subjects with antibodies anti-HCV present and persistently normal ALT level, without fibrosis (Scheuer fibrosis score: 0 points). Concentration of studied parameters was assayed in the serum by immunoenzymatic method before and after the therapy with interferon alpha-2b and ribavirin.

RESULTS: TGF-β1 levels were significantly higher in the study group compared to the control group (35.89 vs 32.37 ng/mL; P = 0.023). Such differences were not found in VEGF and bFGF levels. In patients showing complete response (negative HCV RNA and normal ALT level), significant increase in VEGF (112.8 vs 315.03 pg/mL; P < 0.05) and bFGF (2.51 vs 15.79 pg/mL; P = 0.04) levels were found. Significant decrease in TGF-β1 level was observed both in responders (37.44 vs 30.02 ng/mL; P=0.05), and in non-responders (38.22 vs 30.43 ng/mL; P = 0.043). bFGF levels before the treatment were significantly lower (2.51 vs 5.94 pg/mL; P = 0.04), and after the treatment significantly higher (15.79 vs 4.35 pg/mL; P = 0.01) in patients with complete response than in those with no response.

CONCLUSION: Among the analyzed parameters TGF-β1 seems to play the most important role in the pathogenesis of fibrosis in CHC. Levels of this factor are significantly lower in subjects who do not have fibrosis developed in them. Good therapeutic effect in CHC patients is associated with significant changes in TGF-β1, VEGF, and bFGF levels. bFGF seems to have the highest usefulness in the prognosis of treatment efficacy.

Intrahepatic cytokine profile in renal-transplant patients infected by hepatitis C virus

In order to examine the immunopathogenesis of hepatitis C virus (HCV)-related liver injury in renal-transplant patients, intra-hepatic cytokine profiles were examined in 38 liver biopsies from 38 patients by measuring messenger RNA (mRNA) concentrations by a real-time PCR method of a Th1 cytokine (i.e., interferon (IFN)-gamma), a Th2 cytokines (i.e., interleukine (IL)-10), a proinflammatory cytokine (i.e., IL-8), and a potent fibrogenic factor (transforming growth factor [TGF]-beta). There was no significant difference in TGF-beta, IFN-gamma, IL-10, or IL-8 levels of expression according to liver-activity grade, liver-fibrosis stage, the concentration of HCV RNA at liver biopsies, or the HCV genotype. However, IFN-gamma/beta-actin mRNA concentration was higher than the IL-10/beta-actin mRNA concentration in patients with F3 Metavir score. Median IFN-gamma/beta-actin mRNA concentration tended to be higher in patients with A3 and A4 Metavir activity grades compared with those with A0 and A1 activity grades. There was a significant correlation between the duration of HCV infection and both TGF-beta/beta-actin (r(2)=0.19, P=0.04) and IL-8/beta-actin mRNA concentrations (r(2)=0.19, P=0.03). IFN-gamma/beta-actin mRNA concentration also increased according to the duration of HCV (r(2)=0.19, P=0.07). Finally, there was a significant correlation between the duration of HCV infection and liver fibrosis stage (r(2)=0.17, P=0.045). Intrahepatic Th1 cytokine profile seems to be predominant in patients with extensive fibrosis and activity scores, suggesting that it might be responsible for liver injury in renal transplant patients.

Noninvasive assessment of liver fibrosis

Understanding of the pathogenesis of hepatic fibrosis on a molecular level has led to the identification of several putative serum markers of hepatic fibrosis. Either individually or in combination, these serum markers appear capable of determining early and advanced hepatic fibrosis. Radiological determination of hepatic fibrosis has insufficient sensitivity and specificity other than for detection of features of portal hypertension or features of end-stage cirrhosis. Transient hepatic elastography is a novel technology demonstrating promise as a noninvasive means of fibrosis determination. This article outlines the accuracy of all these modalities in the diagnosis of hepatic fibrosis and discusses how they may be incorporated into clinical practice.

Hepatitis C virus core variants isolated from liver tumor but not from adjacent non-tumor tissue interact with Smad3 and inhibit the TGF-beta pathway

Hepatitis C virus (HCV) is a major risk factor for human hepatocellular carcinoma (HCC) but the mechanisms underlying HCV-induced carcinogenesis are still poorly understood. We have hypothesized that viral variants, selected during long-term infection, might contribute to cellular transformation. To address this issue, we have investigated the effect of natural HCV core variants isolated from liver tumors (T), or their non-tumor (NT) counterparts, on the tumor growth factor-beta (TGF-beta) pathway, a major regulator of cellular proliferation, differentiation and apoptosis. We have found a significant reduction in TGF-beta reporter gene activity with the expression of core sequences isolated from liver tumors. In contrast, moderate or no effects were observed with non-tumor mutants or a core reference sequence. The molecular mechanisms have been characterized and involved the inhibition, by tumor-derived cores, of the DNA-binding activity of the Smad3/4 transcription factors complex. This inhibition occurs through a direct interaction between the central domain (amino acids 59-126) of tumor-derived core and the MH1 DNA-binding domain of Smad3, thus preventing its binding to DNA. We have therefore identified a new cell-signaling pathway targeted by HCV core and inhibited by tumor-derived core sequences. These results suggest that during chronic infection, there is selection of viral variants that may promote cell transformation by providing, to clonally expanding cells, resistance to TGF-beta antiproliferative effects.

TGF-beta1 mRNA expression in liver biopsy specimens and TGF-beta1 serum levels in patients with chronic hepatitis C before and after antiviral therapy

BACKGROUND AND OBJECTIVE

Transforming growth factor (TGF)-beta1 is the best-characterized profibrogenic cytokine. TGF-beta1 increases the production of extracellular matrix proteins and their receptors and inhibits the synthesis of matrix degrading proteolytic enzymes. We undertook this study to simultaneously evaluate the effect of interferon alpha 2b plus ribavirin therapy on TGF-beta1 daily serum levels and on mRNA TGF-beta1 expression in liver biopsy specimens from 60 patients with chronic hepatitis C.

METHODS

Serum levels of TGF-beta1 were measured by ELISA. The levels of the RNAs in liver biopsy specimens were measured by quantitative reverse transcriptase polymerase chain reaction. After treatment, patients were divided into two groups: 34 responders [undetectable hepatitis C virus (HCV)-RNA, normal ALT levels, decrease in histology activity index compared with pretreatment liver biopsy] and 26 non-responders (detectable HCV-RNA, elevated ALT levels, no decrease in the histology activity index).

RESULTS AND DISCUSSION

In patients with hepatitis C, the 'responders' to the antiviral treatment showed significant decreases in both mean daily serum TGF-beta1 levels and mRNA TGF-beta1 expression in the liver biopsy specimens. The 'non-responders' serum TGF-beta1 concentrations did not change significantly, but the mRNA TGF-beta1 expression did.

CONCLUSION

Both serum TGF-beta1 concentration and mRNA TGF-beta1 expression in liver biopsy specimens may be useful as prognostic markers in patients with hepatitis C undergoing antiviral therapy.

Effect of hepatitis C infection on tacrolimus doses and blood levels in liver transplantation recipients

BACKGROUND

In our cohort of patients with hepatitis-C virus, which is the most common indication for liver transplantation, we have noted higher relative blood levels of tacrolimus compared to patients without hepatitis-C virus.

AIM

To verify this observation and determine its clinical significance, we performed a comparison of doses and blood levels of tacrolimus in hepatitis-C virus and non- hepatitis-C virus liver transplantation recipients.

METHODS

Tacrolimus dose and trough level, as well as mean alanine aminotransferase, for all patients transplanted at our center with a deceased donor between 1/1995 and 12/1999 with hepatitis-C virus were recorded at monthly intervals during the first 24 months following transplantation and compared to patients without hepatitis-C virus.

RESULTS

The tacrolimus levels for hepatitis-C virus and non-hepatitis-C virus patients were not significantly different at any of the monthly intervals, except month 9. In addition, the overall mean tacrolimus levels for hepatitis-C virus and non-hepatitis-C virus patients were not significantly different (P = ns). However, the mean tacrolimus dose (mg/kg) was significantly higher for hepatitis-C virus patients at 12, 15, 18, 21 and 24 months, P < 0.01. The total mean tacrolimus dose in hepatitis-C virus patients was lower during year one by 39% (P = 0.018) and by 73% (P = 0.001) during year two. The total difference in cost of tacrolimus (for year one and two) administered to hepatitis-C virus patients was $4920, P = 0.03. The serum alanine aminotransferase was significantly higher in hepatitis-C virus patients at each monthly interval except month 1, P < or = 0.01.

CONCLUSIONS

Liver transplant recipients with hepatitis-C virus require significantly lower oral doses of tacrolimus to achieve the same blood levels compared to non-hepatitis-C virus patients. This difference may result in a significant reduction in the cost of tacrolimus in hepatitis-C virus patients. The most likely explanation for these findings is decreased hepatic clearance of tacrolimus caused by mild hepatic injury from recurrent hepatitis-C virus.

Transforming growth factor-β1 gene polymorphisms are associated with progression of liver fibrosis in Caucasians with chronic hepatitis C infection

AIM: Considerable attention is focused on polymorphisms in the gene encoding transforming growth factor-β1 (TGF-β1), a multifunctional cytokine that is in turn a potent growth inhibitor involved in wound healing and differentiation. In humans, it promotes the pathogenesis of organ fibrosis, atherosclerosis, cancer, autoimmune and inflammatory diseases, keloid disease, and hypertrophic scarring. For this reason, much emphasis has been placed on studies elucidating the impact of TGF-β1 and its gene variations for the susceptibility and pathogenesis of these diseases. Unfortunately, some studies have serious limitations.

METHODS: We have recently described a high-throughput method for investigation the Arg25Pro polymorphism of human TGF-β1 gene and showed that the frequency of the Pro25 allele is significantly associated with hepatic fibrogenesis. In this report, we describe two novel LightCycler (LC) techniques that facilitate the examination of the two other known alterations in the coding region of TGF-β1. We investigated whether these polymorphisms contribute to hepatitis-induced progression of fibrogenesis in Chinese and Caucasians.

RESULTS: In the Chinese ancestry, the gene polymorphisms at codons 25 and 263 were not found and the genetic variant at codon 10 is unlikely to confer susceptibility to hepatic fibrosis. Contrarily, in Caucasians TGF-β1 allelic variations are more frequent and the presence of prolines either in codon 25 or 10 is associated with the interindividual variability in developing more severe fibrosis during chronic hepatitis C infection.

CONCLUSION: In summary, these results confirm the hypothesis that TGF-β1 polymorphisms are associated with fibrosis progression in Caucasians chronically infected with hepatitis C.

Suppression of hepatitis C virus replicon by TGF-beta

Hepatitis C virus (HCV) is one of the major causative agents of liver diseases, such as liver inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma. Using an efficient HCV subgenomic replicon system, we demonstrate that transforming growth factor-beta (TGF-beta) suppresses viral RNA replication and protein expression from the HCV replicon. We further show that the anti-viral effect of this cytokine is associated with cellular growth arrest in a manner dependent on Smad signaling, not mitogen-activated protein kinase (MAPK) signaling. These results suggest a novel insight into the mechanisms of liver diseases caused by HCV.

Negative regulation of NK cell activities by inhibitory receptor CD94/NKG2A leads to altered NK cell-induced modulation of dendritic cell functions in chronic hepatitis C virus infection

NK cells are potent activators of dendritic cells (DCs), but it remains obscure how third-party cells affect the ability of NK cells to modulate DC functions. We show here that NK cells derived from healthy donors (N-NK), when cocultured with human liver epithelial cells, induced maturation as well as activation of DCs, such as increased migratory capacity as well as T cell stimulatory activity. In contrast, NK cells from chronic hepatitis C virus-infected donors (HCV-NK) were not capable of activating DCs under the same conditions. In comparison to N-NK, HCV-NK showed higher expression of CD94/NKG2A and produced IL-10 and TGFbeta when cultured with hepatic cells, most of which express HLA-E, a ligand for CD94/NKG2A. Blockade of NKG2A restored the ability of HCV-NK to activate DCs, which appeared to result from the reduced NK cell production of IL-10 and TGFbeta. The blockade also endowed HCV-NK with an ability to drive DCs to generate Th1-polarized CD4+ T cells. These findings show that NK cell modulation of DCs is regulated by third-party cells through NK receptor and its ligand interaction. Aberrant expression of NK receptors may have an impact on the magnitude and direction of DC activation of T cells under pathological conditions, such as chronic viral infection.

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.

Role of cytokine gene polymorphism and hepatic transforming growth factor β1 expression in recurrent hepatitis C after liver transplantation

Recurrent hepatitis C virus (HCV) infection after orthotopic liver transplantation (OLT) is nearly universal. Cytokines play an important role in the immune response to viral infection, and cytokine gene polymorphism affects the overall expression and secretion of cytokines. The objective of this study was to define the relationship between cytokine polymorphism and recurrent hepatitis C after OLT. Blood samples were collected from 36 patients at a mean of 44.6+/-30.4 months after OLT for chronic HCV infection. DNA was extracted from peripheral blood mononuclear cells, and polymerase chain reaction-sequence specific primers (PCR-SSP) analysis was performed on promoter sequences of transforming growth factor beta1 (TGF-beta1), interleukin 6 (IL-6) interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-alpha) and interferon gamma (INF-gamma). Liver biopsies performed at diagnosis of recurrent disease were graded with the Knodell score, and hepatic TGF-beta1 expression was determined semiquantitatively by immunohistochemistry. The gene polymorphism of TGF-beta1 was correlated with its expression on hepatocytes and sinusoids. Polymorphism in all studied cytokine genes was correlated with recurrence, and interval to recurrence (>12 or < or =12 months post-OLT), and clinical (ascites, Child-Pugh score and death), biochemical parameters of recurrent HCV (serum alanine aminotransferase (ALT)), INR, albumin, bilirubin), and virological parameters (HCV genotype and load). Biopsies revealed recurrent HCV in 31 patients (86.1%); in 21 (67.7%), the interval to recurrence was 12 months. There was a statistically significant correlation between TGF-beta1 gene polymorphism, i.e., the genetic ability to produce high levels of TGF-beta1, and the intensity of TGF-beta1 staining on hepatocytes (p=0.003) and sinusoids (p=0.003), and the degree of fibrosis (p=0.02). A borderline correlation was found with the presence of ascites (p=0.007), but not with Child-Pugh score, synthetic liver function tests or HCV genotype and load. The genetic ability to produce low levels of IFN-gamma was correlated with recurrent disease (p=0.015). No such correlation was found for TGF-beta1 gene polymorphism. In conclusion, polymorphism in the TGF-beta1 gene correlates with its in situ hepatic expression in patients with recurrent HCV after liver transplantation. INF-gamma, but not TGF-beta1 gene polymorphism, correlates with early recurrent hepatitis C after transplantation. These findings might help to design preemptive prevention therapy in selected patients at risk.

Evaluation of liver fibrosis: a concise review

The diagnosis of liver fibrosis has traditionally relied on liver biopsy. However, recent studies have suggested that there can be up to a 33 % error in the diagnosis of cirrhosis. In this article, we review the current status of liver biopsy as a gold standard for the diagnosis of liver fibrosis and discuss the radiological and serum tests that have been proposed as potential adjuncts or alternatives to biopsies. Indirect markers of liver fibrosis which reflect alterations in liver function and or inflammation are discussed as well as more direct markers of liver fibrosis. The limitations of utilization of these markers for both cross-sectional diagnosis of fibrosis and monitoring disease progression or regression are discussed.

Expression of the CXCR3 ligand I-TAC by hepatocytes in chronic hepatitis C and its correlation with hepatic inflammation

The factors that regulate lymphocyte traffic in chronic hepatitis C (CHC) are not completely defined. Interferon (IFN)-inducible T cell alpha chemoattractant (I-TAC) is a relatively new member of the CXCR3 chemokine ligand family that selectively recruits activated T cells to sites of inflammation. To determine if I-TAC plays a role in CHC, we investigated I-TAC expression in hepatitis C virus (HCV)-infected liver biopsy material. I-TAC messenger RNA (mRNA) levels were significantly increased in HCV-infected liver compared with normal liver, which correlated with both portal and lobular inflammation. I-TAC expression was localized to hepatocytes throughout the liver lobule, with those in close proximity to active areas of inflammation expressing the highest concentration of I-TAC. In vitro, I-TAC mRNA and protein expression was inducible in Huh-7 cells following either IFN-alpha or -gamma stimulation and synergistically with tumor necrosis factor (TNF)-alpha. Furthermore, transfection of Huh-7 cells with either poly(I:C) or HCV RNA representing the HCV subgenomic replicon induced I-TAC mRNA expression. HCV replication was also found to modulate I-TAC expression, with stimulation of Huh-7 cells harboring either the HCV subgenomic or genomic replicon showing significantly increased synergistic effects compared with those previously seen in Huh-7 cells alone with IFN-gamma and TNF-alpha. In conclusion, these results suggest I-TAC, one of the most potent chemoattractants for activated T cells, is produced by hepatocytes in the HCV-infected liver and plays an important role in T cell recruitment and ultimately the pathogenesis of CHC.

Parenchymal transforming growth factor beta-1: its type II receptor and Smad signaling pathway correlate with inflammation and fibrosis in chronic liver disease of viral etiology

BACKGROUND AND AIMS

Transforming growth factor-beta (TGF-beta) system is involved in the control of cell growth and extracellular matrix formation. Previous studies in patients with chronic liver disease have shown that increased TGF-beta expression significantly correlates with the degree of hepatic fibrosis. The aim of our study was to define TGF-beta system expression in hepatic parenchymal cells and its significance in patients with differing extents of chronic liver disease of viral etiology.

METHODS

Expression of TGF-beta 1, TGF-beta 1 type II receptor (TGF-beta RII) and the Smad signaling pathway was evaluated in consecutive liver sections of 77 patients with chronic liver disease (65 HCV positive and 12 HBV positive). Results were correlated with histological scores and apoptotic activity.

RESULTS

TGF-beta 1 was demonstrated in the liver of 30/56 (53.6%) patients with chronic hepatitis and 20/21 (95%) patients with cirrhosis, but in none of the 20 normal livers. Positive cytokine reaction was seen both in stromal cells and hepatocytes. Expression of TGF-beta RII and Smad proteins showed a distribution pattern similar to that of TGF-beta, with a direct correlation in terms of immunoreactivity extent. A significant correlation was found between parenchymal expression of TGF-beta system and inflammatory and fibrosis scores. No correlation was found with apoptotic index and other morphological, clinical or virological parameters.

CONCLUSIONS

The TGF-beta system is up-regulated at the ligand, receptor and signaling level in the liver of patients with more active disease. The strong expression of TGF-beta and the Smad pathway in parenchymal cells suggests that hepatocytes, in addition to mesenchymal cells, may play an important role in the progression of liver disease.

Hepatitis C virus core protein expression leads to biphasic regulation of the p21 cdk inhibitor and modulation of hepatocyte cell cycle

Hepatitis C virus (HCV) Core protein is implicated in viral pathogenesis by the modulation of hepatocyte gene expression and function. To determine the effect of Core protein on the cell-cycle control of hepatocytes, a HepG2 cell line containing a Flag-tagged Core under the control of an inducible promoter was generated. Initial Core protein expression included the presence of unprocessed (191 aa) and processed (173 aa) forms of the Core proteins with the processed form becoming dominant later. Expression of the 191 aa form of Core protein corresponded to an increase in the expression of the p21, a decrease in cdk2-dependent kinase activity, and a decrease in the percentage of cells in S-phase along with an accumulation of cells in the G(0)/G(1) phase of the cell cycle. As the processed form accumulated, the p21 levels started to decline, suggesting that Core protein regulates p21 expression in a biphasic manner. These findings implicate Core protein in potentially modulating hepatocyte cell cycle differentially in the early stages of infection through biphasic regulation of p21 cdk kinase inhibitor.

Transforming growth factor beta in hepatitis C virus infection: in vivo and in vitro findings

BACKGROUND

Hepatitis C virus (HCV) is a leading cause of chronic liver disease (CLD) worldwide. The chronicity is a result of viral persistence and the ability of the virus to escape from the immune mechanisms of the host. Transforming growth factor (TGF)-beta is a cytokine thought to be responsible for viral persistence and liver fibrogenesis.

METHODS

The present study examined the levels of TGF-beta messenger (m)RNA by reverse transcription polymerase chain reaction (RT-PCR) in 35 liver biopsies and HCV-transfected HepG2 cells.

RESULTS

Transforming growth factor-beta mRNA was detected in nine liver biopsies from patients with chronic HCV infection, but was not detected in patients with non-HCV-related CLD or controls. On quantitation by semiquantitative PCR, TGF-beta mRNA levels ranged from 10-4.75 to 10-12.8 amol (10-7.46 +/- 3.771) in liver biopsies of HCV-related CLD. No significant difference in TGF-beta receptor levels was observed by RT-PCR in HCV- or non-HCV-related CLD by immunohistochemistry. To correlate these findings with in vitro experiments, levels of TGF-beta mRNA and its receptors were determined by RT-PCR in HepG2 cells transfected with HCV and hepatitis B virus (HBV) constructs, using mock-transfected cells as control. The TGF-beta protein levels were quantitated in these cell supernatants by enzyme immunoassay. The TGF-beta mRNA and protein levels were two logs and approximately 30 times higher in HCV-transfected HepG2 cells than in HBV- and mock-transfected cells, respectively. The TGF-beta receptors in HepG2 cells were also downregulated in HCV-transfected cells as compared with mock-transfected cells.

CONCLUSION

These observations suggest upregulation of TGF-beta in HCV infection and a probable role for TGF-beta in the pathogenesis of HCV-related CLD.

Prediction of progressive liver fibrosis in hepatitis C infection by serum and tissue levels of transforming growth factor-beta

Although many patients with chronic viral hepatitis C infection suffer from progressive liver disease, the rate of fibrosis progression is highly variable and some patients do not show any measurable progression. However, our ability to predict which patients progress is very limited. Since transforming growth factor-beta (TGF-beta) is a key mediator of liver fibrogenesis, we assessed the predictive role of TGF-beta for fibrogenesis in chronic hepatitis C. We studied 39 patients with chronic hepatitis C in whom two liver biopsies were taken at least 12 months apart, and who did not receive therapy during this period. TGF-beta was measured by bioassay and by ELISA in serum samples taken at the time of the first biopsies, and TGF-beta was determined semiquantitatively by immunostaining of liver biopsy sections. Fibrosis was scored blinded in the biopsy samples by two pathologists independently. There was a close correlation between TGF-beta serum levels and the rate of fibrosis progression. Patients with no progression of fibrosis had significantly lower (59 ng/mL +/- 22) TGF-beta serum levels than patients with progressive disease (115 ng/mL +/- 20), and a TGF-beta level below 75 ng/mL was predictive for stable disease. Immunohistology for TGF-beta in biopsy samples was also predictive for progressive liver disease with fibrosis progression found in those patients displaying staining of hepatocytes and sinusoidal cells. No such correlation was found with other markers such as procollagen III peptide, viral load or transaminase levels. These results further support the role of TGF-beta in liver fibrogenesis, and offer an opportunity to predict clinical disease progression, which may help in selecting patients who are in need of therapeutic interventions.

Plasma transforming growth factor-beta1 level and efficacy of alpha-tocopherol in patients with non-alcoholic steatohepatitis: a pilot study

BACKGROUND

Non-alcoholic steatohepatitis is a distinct entity, characterized by fatty change, lobular inflammation and fibrosis of the liver. Some cases of non-alcoholic steatohepatitis progress to cirrhosis, but it is not easy to distinguish this disease from non-alcoholic fatty liver by non-invasive examinations. No proven therapy for non-alcoholic steatohepatitis exists. Transforming growth factor-beta1 is implicated in the development of liver fibrosis, and is inhibited by alpha-tocopherol (vitamin E) in the liver. Therefore, in this study, the significance of the measurement of the level of plasma transforming growth factor-beta1 and the effect of alpha-tocopherol on the clinical course of non-alcoholic steatohepatitis were investigated.

METHODS

Twelve patients with non-alcoholic steatohepatitis and 10 patients with non-alcoholic fatty liver, with a diagnosis confirmed by liver biopsy, were studied. None of the patients had a history of alcohol abuse, habitual medicine or malignant or inflammatory diseases. All patients were negative for hepatitis B, C and G virus. Patients were given dietary instruction for 6 months, and then alpha-tocopherol (300 mg/day) was given for 1 year. Blood chemistries, measurement of plasma transforming growth factor-beta1 level and liver biopsies were undertaken before and after the 1-year alpha-tocopherol treatment.

RESULTS

The serum alanine transaminase level decreased in non-alcoholic fatty liver patients, but not in non-alcoholic steatohepatitis patients, after 6 months of dietary therapy. Although the serum alanine transaminase level in non-alcoholic steatohepatitis patients was reduced during the 1-year alpha-tocopherol treatment, alpha-tocopherol had no effect on the serum alanine transaminase level in non-alcoholic fatty liver patients. The histological findings, such as steatosis, inflammation and fibrosis, of the non-alcoholic steatohepatitis patients were improved after alpha-tocopherol treatment. The plasma transforming growth factor-beta1 level in non-alcoholic steatohepatitis patients was significantly elevated compared with that in non-alcoholic fatty liver patients and healthy controls, and decreased, accompanied by an improvement in serum alanine transaminase level, with alpha-tocopherol treatment.

CONCLUSIONS

Our data suggest that the measurement of the level of plasma transforming growth factor-beta1 represents a possible method of distinguishing between non-alcoholic steatohepatitis and non-alcoholic fatty liver. Long-term alpha-tocopherol treatment may be safe and effective for non-alcoholic steatohepatitis. A randomized, controlled, double-blind trial is needed to confirm the full potential of alpha-tocopherol in the management of non-alcoholic steatohepatitis.

In situ expression of transforming growth factor-beta1-3, latent transforming growth factor-beta binding protein and tumor necrosis factor-alpha in liver tissue from patients with chronic hepatitis C

BACKGROUND

The mechanisms determining liver damage in chronic hepatitis C remain unclear. The aim was to evaluate the in situ expression of transforming growth factor beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha), two key cytokines implicated as important pathogenic mediators in the development of liver fibrosis.

METHODS

In situ expression of TNF-alpha and of TGF-beta isoforms 1-3, and its transport protein latent TGF-beta binding protein (LTBP), was determined by immunohistochemistry in 9 untreated patients with chronic hepatitis C infection and in 6 controls without liver disease. In addition, TGF-beta1 expression was analyzed in 10 HCV patients before and after treatment with interferon-alpha alone, or in combination with ribavirin.

RESULTS

Liver biopsies from HCV patients showed positive staining for TGF-beta1-3 isoforms and LTBP, and to a lesser degree for TNF-alpha, in areas with inflammation and fibrosis. Normal control liver showed no positive staining. TGF-beta1 expression before treatment, quantified by morphometric analysis, did not differ between non-responders and sustained responders. In patients responding to therapy, TGF-beta1 expression decreased in parallel with histological improvement, while no difference in TGF-beta1 expression was seen before and after treatment in non-responders.

CONCLUSION

These results suggest that TNF-alpha and all three isoforms of TGF-beta are involved in the pathogenesis of HCV related liver disease, and that treatment leading to eradication of the virus affects the expression of TGF-beta1.

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.