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Nonalcoholic steatohepatitis (NASH) is a liver disease that complicates insulin-resistant states. This trial tested the efficacy and safety of rosiglitazone, an insulin-sensitizing agent, in patients with NASH.Sixty-three patients with histologically proven NASH were randomly assigned to receive rosiglitazone (4 mg/day for the first month and 8 mg/day thereafter; n = 32) or placebo (n = 31) for 1 year. Liver biopsy was performed at the end of treatment. End points were improvement in the histologic score of steatosis, normalization of serum transaminase levels, and improvement in necroinflammation and fibrosis.More patients treated with rosiglitazone than receiving placebo had improved steatosis (47% vs 16%; P = .014) and normalized transaminase levels (38% vs 7%; P = .005), although only half of patients responded. There was no improvement in other histologic lesions, including fibrosis, and a composite score of activity, the nonalcoholic fatty liver disease activity score. Improvement of steatosis correlated with reduction of transaminase levels (r = 0.36; P.005), improvement in insulin sensitivity (r = 0.34; P = .008), and increase in adiponectin levels (r = -0.54; P.01) but not with weight variations. Independent predictors of response were rosiglitazone treatment, the absence of diabetes, and massive steatosis. Weight gain was the main adverse effect (mean gain of 1.5 kg in the rosiglitazone group vs -1 kg in the placebo group; P.01), and painful swollen legs was the main reason for dose reduction/discontinuation. Serum hemoglobin level was slightly but significantly reduced. There was no hepatic toxicity.In patients with NASH, rosiglitazone improves steatosis and transaminase levels despite weight gain, an effect related to an improvement in insulin sensitivity. However, there is no improvement in other parameters of liver injury.

Background. Chronic hepatitis C virus (HCV) is usually associated with high levels of hepatic interleukin (IL)-2 and low levels of IL-4 transcripts. HCV frequently recurs after liver transplantation, and its course is accelerated in this setting. We compared in situ expression of IL-2 and IL-4 in transplanted and nontransplanted patients with HCV. Methods. A total of 74 liver biopsy specimens were studied; 52 came from transplanted patients, 38 of whom were HCV-positive (17 mild and 21 severe cases of recurrent HCV) and 22 came from nontransplanted patients, 17 of whom were HCV-positive (7 mild and 10 severe cases of HCV). The expression of IL-2 and IL-4 mRNA and IL-4 protein was studied using the reverse transcriptase polymerase chain reaction and immunohistochemical methods, respectively. Results. IL-2 transcript levels were significantly higher in severe than in mild HCV in both liver graft recipients and nontransplanted patients. However, IL-2 levels were higher in nontransplanted than in transplanted patients. IL-4 transcripts and protein were preferentially detected in graft recipients with severe recurrent HCV. Conclusion. IL-4 expression is elevated in severe recurrent HCV and may play a role in the progression of hepatic lesions after liver transplantation.

IL-4 is overexpressed in liver grafts during severe recurrent hepatitis C and rejection. Hepatocyte apoptosis is involved in both these phenomena. We therefore examined the proapoptotic effect of IL-4 on HepG2 cells and human hepatocytes in vitro, together with the underlying mechanisms. We first measured IL-4 receptor expression, STAT6 activation by IL-4, and STAT6 inhibition by an anti-IL-4 antibody or by STAT6 siRNA transfection. We then focused on the pathways involved in IL-4-mediated apoptosis and the role of STAT6 activation in apoptosis initiation. The IL-4 receptor was expressed on both cell types, and STAT6 was activated by IL-4. Both anti-IL-4 and STAT-6 siRNA inhibited this activation. IL-4 induced apoptosis of both HepG2 cells (P=0.008 vs. untreated control) and human hepatocytes (P

Alcohol consumption has a major impact on the natural history of chronic hepatitis C virus (HCV) infection, although the underlying mechanisms are still debated. We designed a clinical study to evaluate the impact of alcohol abuse on both viral load and expression of low-density lipoprotein receptor (LDLR) and CD81 expression. Thirty-eight consecutive HCV-infected patients were enrolled. Group 1 (n = 18),or =10 g alcohol/day, group 2 (n = 8),or =30 g alcohol/day, group 3 (n = 12),or =30 g alcohol/day. Receptors expression was measured by flow cytometry analysis in peripheral blood mononuclear cells (PBMC) and by specific real-time retrotranscription polymerase chain reaction (RT-PCR) in the liver. Serum viral load was evaluated by quantification of both HCV genomic RNA and total core antigen. The hepatic viral load was assessed by real-time RT-PCR. Serum HCV-RNA and total core antigen were significantly correlated, and were higher, albeit not significantly, in group 3 than in group 1. Alcohol consumption had no effect on expression of HCV putative receptors in PBMC, except for CD81, which was upregulated on monocytes in group 2. In the liver, viral load and levels of LDLR transcripts were significantly higher in group 3 than in group 1. Remarkably, a significant positive correlation was found between LDLR transcripts and HCV-RNA (r2 = 0.83, P10(-3)). Finally, in vitro experiments suggested that the effect of ethanol on LDLR expression was indirectly mediated by both tumour necrosis factor-alpha and interleukin-1beta. In conclusion, this study is the first to support a role for LDLR in the natural infection by HCV in man.

The detection of negative-strand hepatitis C virus (HCV) RNA is a hallmark of replication. A highly sensitive and specific method is required to quantify the very low level of replication inherent to in vitro infection systems. Based on reverse transcription with a tagged primer in the 5′ non-coding region of the HCV genome, followed by a nested PCR with a second round of real-time PCR, a novel method is described with improved sensitivity for negative-strand HCV RNA quantification. The lower detection level was 25 copies per reaction of negative-strand HCV RNA, even in the presence of 1 × 105 copies of positive-strand HCV RNA. This protocol was applied to the detection of negative HCV strand RNA in the liver of HCV-infected patients as well as in primary human hepatocytes infected in vitro. In both models, and particularly in each of three, independent in vitro infection experiments, this assay permitted the quantitation of HCV replication. J. Med. Virol. 79:155–160, 2007. © 2006 Wiley-Liss, Inc.

Most individuals exposed to hepatitis C virus (HCV) become chronically infected and are predisposed to liver disease. The mechanisms underlying viral persistence and disease progression are unknown. A role for the HCV NS5A protein in viral replication and interferon resistance has been demonstrated. To identify mechanisms affected by NS5A, we analyzed the gene expression of Huh7 cells expressing NS5A and control cells using oligonucleotide microarrays. A set of 103 genes (43 up-regulated, 60 down-regulated) whose expression was modified by at least twofold was selected. These included genes involved in cell adhesion and motility, calcium homeostasis, lipid transport and metabolism, and genes regulating immune responses. The finding of modulated expression of genes related to the TGF-beta superfamily and liver fibrosis was observed. Interestingly, both the tumor necrosis factor and lymphotoxin beta receptors were down-regulated by NS5A. Similar data were obtained following expression of four NS5A mutants obtained from patients who were not responsive or were sensitive to interferon therapy. Through computational analysis, we determined that 39 of the 43 genes up-regulated by NS5A contained one or more nuclear factor kappaB (NF-kappaB) binding sites within their promoter region. Using the Gibbs sampling method, we also detected enrichment of NF-kappaB consensus binding sites in the upstream regions of the 43 coexpressed genes. Activation of NF-kappaB by NS5A was subsequently demonstrated in luciferase reporter assays. Adenovirus-mediated expression of IkappaBalpha reverted NS5A mediated up-regulation of gene expression. In conclusion, this study suggests a role of NS5A and NF-kappaB in HCV pathogenesis and related liver disease. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

A link between chronic hepatitis C virus (HCV) infection and low-grade B-cell lymphomas has been suggested by epidemiological studies. Marginal zone lymphomas (MZLs) including splenic lymphomas with villous lymphocytes are among the most frequently reported subgroups in the setting of chronic HCV infection. In this study, we examined the effect of antiviral treatment in eight patients with HCV-associated MZL. We found that five out of eight patients have responded to interferon alpha and ribavirin. In some cases, hematologic responses were correlated to virologic responses. In addition, we report a case of large granular lymphocyte leukemia occurring in association with MZL and HCV, and responding to interferon and ribavirin. We suggest that there is an etiologic link between HCV and antigen-driven lymphoproliferative disorders.

Background. The aim of this study was to evaluate calcineurin activity and interleukin-2 (IL-2) expression by peripheral blood cells as a means of assessing the immune status of liver transplant recipients. Methods. Twenty-one patients were studied in a randomized study comparing cyclosporine and tacrolimus as the main immunosuppressive drug. Calcineurin activity was determined after separation of phosphorylated and dephosphorylated products of a calcineurin specific peptide substrate by high performance liquid chromatography (HPLC). Intracellular IL-2 expression was measured by flow cytometry. In 34 additional patients, intracellular IL-2 expression was prospectively measured. Results. Calcineurin activity fell after transplantation. Values were marginally higher in patients with acute rejection (P=0.059). The percentage of IL-2-producing T cells fell after transplantation. This percentage did not differ between patients with and without rejection. In contrast, the proportion of IL-2-producing CD8+ T cells was higher in patients with acute rejection than in patients free of acute rejection (P=0.003). Moreover, pretransplantation IL-2 expression by CD8+ T cells was higher in patients who subsequently developed acute rejection, suggesting that IL-2 production may be constitutively higher in those patients. The results obtained in the 34 additional patients confirmed these results. Conclusions. These data suggest that quantification of intracellular IL-2 in CD8+ T cells may be a useful index of immune status in liver transplant recipients. Preoperative IL-2 levels might serve to individually tailor the immunosuppressive regimen.

We have previously shown that cholestasis and bile acids inhibit 2', 5' oligoadenylate synthetase (OAS) activity in the liver and in primary hepatocyte cultures. Here, we assessed the influence of bile acids on interferon (IFN) pathway activation in three hepatoma cell lines. In HepG2 cells, bile acids (100-200 micromol/L) inhibited IFN-induced 2',5' OAS activity to an extent depending on their surface activity index. In Western blot analysis, IFN-induced expression of two major antiviral proteins, MxA and OAS p100, was reduced by 54% +/- 8% and 44% +/- 12%, respectively, when cells were preincubated for 4 hours with 100 micromol/L chenodeoxycholic acid (CDCA). In the same conditions, CDCA did not modify the IFN-induced signal transducers and activators of transcription (STAT)s tyrosine phosphorylation. In contrast, it reduced IFN-induced MxA promoter activity by 60%. The inhibitory effect of CDCA was not mediated by a 4beta-phorbol 12beta-myristate 13alpha-acetate (PMA)-sensitive protein kinase C (PKC)-dependent pathway. Finally, using CHO cells stably expressing a functional human bile acid carrier (Na+-dependent taurocholate cotransporting polypeptide [NTCP]), we found that bile acid inhibition of the IFN pathway occurred in the range of more physiological concentrations (12-50 micromol/L). In summary, our results provide strong evidence that bile acids inhibit the induction of proteins involved in the antiviral activity of IFN. This might partly explain the lack of responsiveness to IFN therapy in some patients with advanced chronic viral liver diseases.

Background/Aims: The mechanisms involved in resistance to interferon alfa in patients with chronic hepatitis C are unclear. Both cirrhosis and cholestasis have been shown to be predictive of resistance. The aim of this study was to evaluate the influence of cholestasis and bile acids on 2′, 5′-oligoadenylate synthetase and natural killer activities, which are both involved in the antiviral activity of interferon. Methods: 2′, 5′-Oligoadenylate synthetase activity was evaluated in spleen, liver, and isolated hepatocytes from bile duct-ligated rats, and the effect of bile acids in vitro on interferon-induced 2′,5′-oligoadenylate synthetase and natural killer activities was examined in fresh mononuclear cells from healthy subjects. Results: Cholestasis had a time-dependent inhibitory effect on 2′, 5′-oligoadenylate synthetase activity in liver, spleen, and isolated hepatocytes from cholestatic rats (−70%, 86%, and 70% relative to baseline, respectively). In vitro, endogenous bile acids had a concentration-dependent inhibitory effect on interferon-induced 2′,5′-oligoadenylate synthetase and natural killer activities, which was related to their structure. This inhibitory effect correlated with the surface activity index. Conclusions: Cholestasis and bile acids diminish the biological activity of interferon and natural killer activity. The results suggest a decrease in the antiviral defenses in cholestatic conditions.

Endogenous bile acids such as chenodeoxycholic acid have been shown to display a suppressive effect in vitro on mononuclear cell activation. We investigated the signal transduction pathway involved in the effect of chenodeoxycholic acid on monocyte procoagulant activity, a model of monocyte activation. Chenodeoxycholic acid (25 to 250 μmol/L) had a concentration-dependent inhibitory effect on procoagulant activity expressed by endotoxin-stimulated mononuclear cells, with half-maximal and maximal inhibition occurring at concentrations of 100 and 250 μmol/L, respectively. The inhibitory effect of chenodeoxycholic acid was (a) closely mimicked by 4β-phorbol 12β-myristate 13α-acetate (PMA), a protein kinase C activator, but not by forskolin or dibutyryl cyclic AMP, two activators of the protein kinase A-dependent pathway; (b) prevented by staurosporine, a potent protein kinase C inhibitor; (c) partially abolished in protein kinase C-depleted cells; and (d) observed in conditions under which chenodeoxycholic acid, like PMA, significantly increased (41%) protein kinase C activity, as assessed by phosphorylation of exogenous (histone III-S) and endogenous (37-kD protein) substrates. In conclusion, our results (a) provide clear evidence of a marked inhibitory effect of chenodeoxycholic acid on monocyte activation, suggesting a potential role of primary endogenous bile acids in the immune defect associated with cholestasis; and (b) indicate that the inhibition of monocyte activation by chenodeoxycholic acid is mediated by way of protein kinase C activation (HEPATOLOGY 1994;19:1164–1170.)

Cell-mediated immunity is impaired during cholestasis, and there is evidence for the involvement of endogenous bile acids. The aim of this study was to evaluate the effects of individual bile acids on immunity and to determine whether monocytes are a target. The effects of bile acids on the procoagulant activity of human monocytes, a lymphocyte-dependent model of monocyte activation, were assessed. Chenodeoxycholic acid, one of the main human primary bile acids, had a concentration-dependent inhibitory effect on procoagulant activity expressed by endotoxin-stimulated mononuclear cells, with half-maximal and maximal inhibitions at 100 and 250 microM, respectively. The inhibitory concentrations were similar for the procoagulant activity of unstimulated mononuclear cells and for endotoxin-stimulated isolated monocytes. In contrast, ursodeoxycholic acid, a bile acid which has beneficial effects in cholestatic diseases, had no significant inhibitory effects at concentrations up to 250 microM. These results indicate that endogenous bile acids tend to inhibit monocyte activation, suggesting a potential role for primary endogenous bile acids in the immune defect associated with cholestasis; ursodeoxycholic acid, which is devoid of effects on the immune system, may potentially reverse cholestasis-induced immunodeficiency.

The epidemic history of HCV genotype 5a is poorly documented in France, where its prevalence is very low, except in a small central area, where it accounts for 14.2% of chronic hepatitis C cases. A Bayesian coalescent phylogenetic investigation based on the E1 envelope gene and a non-structural genomic segment (NS3/4) was carried out to trace the origin of this epidemic using a large sample of genotype 5a isolates collected throughout France. The dates of documented transmissions by blood transfusion were used to calibrate five nodes in the phylogeny. The results of the E1 gene analysis showed that the best-fitting population dynamic model was the expansion growth model under a relaxed molecular clock. The rate of nucleotide substitutions and time to the most recent common ancestors (tMRCA) of genotype 5a isolates were estimated. The divergence of all the French HCV genotype 5a strains included in this study was dated to 1939 [95% HPD: 1921–1956], and the tMRCA of isolates from central France was dated to 1954 [1942–1967], which is in agreement with epidemiological data. NS3/4 analysis provided similar estimates with strongly overlapping HPD values. Phylodynamic analyses give a plausible reconstruction of the evolutionary history of HCV genotype 5a in France, suggesting the concomitant roles of transfusion, iatrogenic route and intra-familial transmission in viral diffusion.

Background & Aims Although hepatitis C virus (HCV) can be grown in the hepatocarcinoma-derived cell line Huh-7, a cell-culture model is needed that supports its complete, productive infection cycle in normal, quiescent, highly differentiated human hepatocytes. We sought to develop such a system. Methods Primary cultures of human adult hepatocytes were inoculated with HCV derived from Huh-7 cell culture (HCVcc) and monitored for expression of hepatocyte differentiation markers and replication of HCV. Culture supernatants were assayed for HCV RNA, core antigen, and infectivity titer. The buoyant densities of input and progeny virus were compared in iodixanol gradients. Results While retaining expression of differentiation markers, primary hepatocytes supported the complete infectious cycle of HCV, including production of significant titers of new infectious progeny virus, which was called primary-culture–derived virus (HCVpc). Compared with HCVcc, HCVpc had lower average buoyant density and higher specific infectivity; this was similar to the characteristics of virus particles associated with the very-low-density lipoproteins that are produced during in vivo infection. These properties were lost after re-culture of HCVpc in poorly differentiated Huh-7 cells, suggesting that authentic virions can be produced only by normal hepatocytes that secrete authentic very-low-density lipoproteins. Conclusions We have established a cell-culture–based system that allows production of infectious HCV in physiologically relevant human hepatocytes. This provides a useful tool for the study of HCV interactions with its natural host cell and for the development of antiviral therapies.

International audience; Alternative, non-invasive techniques are necessary to monitor the progression of liver disease during chronic hepatitis C. Firstly, because serum is the most accessible material for studies using qPCR in microplates, gene transcription was compared in 219 selected genes involved in the pathogenesis of hepatitis C virus (HCV) infection between sera, PBMCs and liver samples collected simultaneously from five patients infected chronically. Secondly, using sera, gene profiles were compared between HCV-infected patients (n = 10) and healthy controls (n = 10). In addition, the influence of alcohol intake was examined in patients infected with HCV genotype-1. Firstly, amplifiable mRNAs were obtained in all samples. After amplification, significant correlations were observed between: liver versus serum; liver versus PBMCs; and serum versus PBMCs (r(2) = 0.37, r(2) = 0.54, r(2) = 0.49, respectively). A comparison of gene transcription by gene involved in T- and B-cell markers, adhesion molecules, apoptosis, liver matrix turnover and inflammation, revealed comparable, significant correlations between serum and liver, (r(2) = 0.30, r(2) = 0.60, r(2) = 0.51, r(2) = 0.51, r(2) = 0.26, and r(2) = 0.61 respectively). Secondly, a quantitative analysis of gene expression in sera between genotype-1b-infected patients and healthy controls revealed that 41 genes involved closely in T-cell activation and apoptosis were over-expressed significantly in patients infected with HCV. In these patients, alcohol consumption was associated with an increased expression of six genes involved in the inflammatory response, together with a decrease of genes associated with dendritic cell function. It is concluded that in patients infected with HCV, serum can be used to evaluate expression of liver genes. Further prospective studies are clearly needed to validate the initial results and to define the relevant genes.

Interleukin-4 (IL-4) is overexpressed in liver grafts in a context of severe recurrent hepatitis C, during which the development of fibrosis is dramatically accelerated. In this study, we examined the effects of IL-4 on the activation and collagen production of cultured human intrahepatic (myo)fibroblasts (hIHFs), and investigated the underlying mechanisms. The myofibroblastic nature of cells was evaluated morphologically using activation markers (smooth muscle alpha-actin, vimentin and prolyl 4-hydroxylase). Quiescent hIHFs were obtained by cell incubation in serum-free medium or cell culture on Matrigel. We first analyzed IL-4 receptor expression, STAT-6 activation by IL-4, and STAT-6 inhibition by an anti-IL-4 antibody or by STAT-6 small-interfering RNA (siRNA) transfection. We then focused on collagen production, using quantitative real-time PCR to analyze the effect of IL-4 on the mRNA expression of collagens I, III and IV, and on collagen levels in supernatants of hIHFs, using the Sircol collagen assay. hIHFs cultured in plastic wells appeared to be morphologically activated. The expression of activation markers was reduced by serum deprivation or culture on Matrigel, and restored by IL-4 incubation. The IL-4 receptor was expressed by hIHFs, and STAT-6 was activated following incubation with IL-4. Both anti-IL-4 antibody and STAT-6 siRNA transfection inhibited this activation. The treatment of hIHFs with IL-4 increased the mRNA expression of collagens I, III and IV (P

Summary Hepatitis C (HCV) treatment using interferon-α (IFN-α) and ribavirin is recommended in HIV/HCV co-infected patients to prevent liver cirrhosis and liver-related death. However, in addition to its antiviral activity, IFN is a pleiotropic cytokine able to synergistically amplify T-cell autoreactivity. Here, we report for the first time the induction of a subfulminant autoimmune hepatitis (AIH) after four months of a successful treatment of HCV-1b infection using peg-IFN and ribavirin, in a 48-year-old woman co-infected with HIV. Diagnosis was assessed according to the international AIH scoring system, including liver biopsy and confirmed by positive response to steroid challenge.

International audience; BACKGROUND AND AIMS: Liver inflammation, fibrosis, and dyslipidemia are common features in patients with chronic hepatitis C virus (HCV) infection. Because peroxisome proliferator-activated receptor alpha (PPARalpha) is highly expressed in the liver and is involved in the regulation of lipid metabolism and inflammation, we sought to determine whether HCV infection may locally impair PPARalpha expression and activity. METHODS: PPARalpha expression was investigated in liver biopsy specimens of 86 untreated patients with HCV infection and controls, by using real-time polymerase chain reaction (PCR), Western blot analysis, and immunohistochemistry. PPARalpha activity was assessed by quantification of the key gene target carnitine palmitoyl acyl-CoA transferase 1 (CPT1A) messenger RNA (mRNA).The influence of HCV core protein on PPARalpha mRNA expression was analyzed in vitro by real-time PCR in HCV core-expressing HepG2 cells activated with the PPARalpha ligand fenofibric acid. RESULTS: Hepatic concentrations of PPARalpha and CPT1A expressed by hepatocytes were impaired profoundly in the livers of untreated patients with HCV infection compared with controls. A mean decrease of 85% in PPARalpha mRNA expression paralleled with a lack of CPT1A mRNA induction also were observed in HCV core-expressing HepG2 cells compared with controls. CONCLUSIONS: HCV infection is related to altered expression and function of the anti-inflammatory nuclear receptor PPARalpha. These results identify hepatic PPARalpha as one mechanism underlying the pathogenesis of HCV infection, and as a new therapeutic target in traditional treatment of HCV-induced liver injury.

The impact of hepatitis C virus NS5A protein mutations on interferon alfa (IFN-alpha) signaling pathway, cell proliferation, and viability is an important issue that is still under debate. We have therefore combined transient and stable expression in a human hepatocytic cell line (Huh7) of 3 full-length NS5A sequences, isolated from patients with or without response to IFN-alpha therapy. Expression of all 3 NS5A-reduced IFN-alpha global antiviral activity on both vesicular stomatitis virus (VSV) and encephalomyocarditis virus (EMCV) replication. We did not show, however, an effect of these 3 NS5A proteins on double-stranded RNA-dependent kinase (PKR) expression and activity as well as colocalization and coimmunoprecipitation between NS5A and PKR. We also failed to show an effect of the 3 NS5A mutants tested on cell proliferation and viability. Overall, our results support an important role of NS5A in controlling IFN-alpha antiviral activity; they show, however, that PKR-independent mechanisms are implicated, at least in liver-derived cells.

Hepatitis C virus (HCV) is a major etiological agent of chronic liver disease and hepatocellular carcinoma (HCC). We demonstrate herewith that HCV core proteins encoded by sequences isolated from HCC tumor tissues, but not those derived from their non-tumor counterparts in the same liver, co-localise in vitro and in vivo and co-immunoprecipitate with PKR in hepatocytic Huh7 cells. We show that this association in fact augments the autophosphorylation of PKR and the phosphorylation of the translation initiation factor eIF2alpha, which are two markers of PKR activity. The present study therefore identifies a novel model of virus-cell interactions whereby a viral protein, the HCV core, activates PKR activity.

Whereas bile acids in excess depress the cell-mediated immune response, their effects on the humoral response have been little investigated. The aim of this study was to investigate the effects of bile acids on immunoglobulin production. Human peripheral blood mononuclear cells were stimulated for 5 days by Staphylococcus aureus Cowan I (SAC-I). Immunoglobulins, were measured in the supernatants and cell lysates using ELISA. We found that bile acids inhibited IgM production in a dose-dependent manner. The inhibitory effects of 50 muM chenodeoxycholic acid (CDCA) and its glyco- and tauro-conjugates (62, 53 and 51%, respectively) were stronger than those of ursodeoxycholic acid (UDCA) and its conjugates (45, 40 and 34%, respectively). The inhibition of IgG production by CDCA and UDCA was weak (23 and 12%, respectively, at 50 LM). IgA production was not modified. The inhibition of intracellular IgM concentration paralleled that observed in the secreted compartment. By contrast, CDCA enhanced intracellular concentration of IgG. In the absence of significant necrosis or apoptosis, CDCA-mediated inhibition of SAC-I-induced IgM production was significantly correlated to the ability of the bile acid to inhibit cell proliferation (r=0.98; p 0.05). In conclusion, we showed that hydrophobic bile acids strongly depress the primary humoral response. This effect resulted from both an inhibition of cell proliferation, and to a lesser extent from a deficient exocytosis of immunoglobulins. (C) 2001 Elsevier Science Inc. All rights reserved.

Background/Aims: The pathophysiology of chronic hepatitis C and the mechanisms of resistance to interferon α are poorly understood. The aim of this work was to assess the influence of HCV infection and the viral genotype on lymphocyte production of 2′,5′ oligo-adenylate synthetase activity and monocyte production of TNFα and IL1β. Methods: Mononuclear cells from 50 consecutive patients were studied after 6 months of interferon treatment. Patients with persistent viremia (PCR-positive, elevated ALT, n =39) were compared with the PCR-negative patients with normal ALT activity ( n =11) of similar age and sex ratio. Results: Cells from the viremic patients showed lower basal and stimulated 2′,5′ oligo-adenylate synthetase activity, and a lower in vitro response capacity to human recombinant interferon. In contrast, no difference was observed in basal and stimulated TNFα or IL1β production between the two groups. In the PCR-positive patients the viral genotype had no significant influence on the response of mononuclear cells to interferon or endotoxin. Conclusions: These results show that the presence of HCV in blood is associated with an elective defect in interferon system activation, independently of the viral genotype.