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Biomedical subjects

R Poupon

Publications and source records attributed to R Poupon.

At least 55 records · Page 3Linked to original sources
PubMed1999

Phase I and phase II drug-metabolizing enzymes are expressed and heterogeneously distributed in the biliary epithelium.

Tissue expression of drug-metabolizing enzymes influences susceptibility to drugs and carcinogens. Because the biliary epithelium, exposed to bile-borne chemicals, may give rise to drug-induced cholangiopathies and to cholangiocarcinomas, we determined the pattern of expression of drug-metabolizing enzymes in this epithelium. We first demonstrated by blot analyses that biliary epithelial cells (BEC) isolated from human gallbladders display cytochrome P450 (CYP) 1A, 2E1, and 3A, microsomal epoxide hydrolase (mEH), alpha, mu, and pi glutathione S-transferase (GST), transcripts and proteins. We also identified CYP-associated steroid 6beta-hydroxylase activity in BEC. CYP and mEH expression was 5- to 20-fold lower in BEC than in autologous hepatocytes, and further differed by a higher ratio of CYP3A5/CYP3A4, and by CYP1A1 predominance over CYP1A2. alphaGST was highly expressed in both hepatocytes and BEC, while piGST was restricted to BEC. In approximately 50% of individuals, muGST was expressed in hepatocytes and at lower levels in BEC. By using the same antibodies as those used in immunoblots, we could show by immunohistochemistry that CYP2E1, CYP3A, mEH, alpha, mu, and piGST immunoreactivities are expressed and display a heterogeneous distribution in the epithelium lining the entire biliary tract except for small intrahepatic bile ducts that were devoid of CYP3A and alphaGST immunoreactivities. In conclusion, BEC contribute to phase II, and although to a lesser extent than hepatocytes, to phase I biotransformation. The distribution of drug-metabolizing enzymes in BEC suggest that they are heterogeneous in their ability to generate and detoxicate reactive metabolites, which may contribute to specific distributions of cholangiopathies.

Aryl Hydrocarbon Hydroxylases↗
PubMed1999

Effect of pretransplantation ursodeoxycholic acid therapy on the outcome of liver transplantation in patients with primary biliary cirrhosis.

As ursodeoxycholic acid (UDCA) delays the need for transplantation, this could result in patients with more comorbid disease, therefore more likely to have a worse outcome posttransplantation. The aim of this study is to compare posttransplantation outcome in patients who received UDCA versus placebo who subsequently required a liver transplant. Data on all trial patients referred for transplantation were retrospectively collected from three randomized controlled trials of UDCA in patients with primary biliary cirrhosis (PBC). An intent-to-treat analysis was conducted with patients assigned to their original treatment allocation. UDCA and placebo groups were compared at trial entry, transplant referral, just before transplantation, and 1 month and 1 year posttransplantation. From 1987 to 1996, 37 UDCA-treated and 53 placebo patients were referred for transplantation; their age, sex, and serum bilirubin levels were similar at study entry. Immediately before transplantation, these two groups were again similar with respect to age, bilirubin level, Mayo risk score, and serum creatinine level. Posttransplantation survival rates at 1 month were 93.9% in the UDCA group and 88.4% in the placebo group, and 1 year survival rates were 90.3% and 78.4%, respectively (not significant). Posttransplantation, the two groups had similar rates of infection (53.9% v 58%); however, rejection occurred significantly less often in the UDCA group; 42.9% versus 68. 8% in the placebo group (P =.04). The posttransplantation outcome of UDCA-treated patients with PBC is no different from those who were administered placebo. There is no evidence to suggest the beneficial effect of UDCA in delaying the need for transplantation is associated with a worse outcome once liver transplantation becomes necessary.

Age Factors↗
PubMed1999

Hepatocellular hypoxia-induced vascular endothelial growth factor expression and angiogenesis in experimental biliary cirrhosis.

We tested the potential role of vascular endothelial growth factor (VEGF) and of fibroblast growth factor-2 (FGF-2) in the angiogenesis associated with experimental liver fibrogenesis induced by common bile duct ligation in Sprague-Dawley rats. In normal rats, VEGF and FGF-2 immunoreactivities were restricted to less than 3% of hepatocytes. One week after bile duct ligation, hypoxia was demonstrated by the immunodetection of pimonidazole adducts unevenly distributed throughout the lobule. After 2 weeks, hypoxia and VEGF expression were detected in >95% of hepatocytes and coexisted with an increase in periportal vascular endothelial cell proliferation, as ascertained by Ki67 immunolabeling. Subsequently, at 3 weeks the density of von Willebrand-labeled vascular section in fibrotic areas significantly increased. Semiquantitative reverse transcription polymerase chain reaction showed that VEGF(120) and VEGF(164) transcripts, that correspond to secreted isoforms, increased within 2 weeks, while VEGF(188) transcripts remained unchanged. FGF-2 mainly consisting of a 22-kd isoform, according to Western blot, was identified by immunohistochemistry in 49% and 100% of hepatocytes at 3 and 7 weeks, respectively. Our data provide evidence that in biliary-type liver fibrogenesis, angiogenesis is stimulated primarily by VEGF in response to hepatocellular hypoxia while FGF-2 likely contributes to the maintenance of angiogenesis at later stages.

Animals↗
PubMed1999

Clinical and biochemical expression of the histopathological lesions of primary biliary cirrhosis. UDCA-PBC Group.

BACKGROUND/AIMS: This study aimed to assess the relationships which may link elementary histological lesions with symptoms and biochemistries in primary biliary cirrhosis. METHODS: We studied 103 patients with primary biliary cirrhosis who participated in a double-blind, placebo-controlled trial of UDCA treatment and in whom liver biopsy specimens obtained at entry were reassessed. Relationships between histological features, fatigue, pruritus and biochemistries were calculated by using exact tests for 2 ordinal variables. RESULTS: The degrees of severity of fatigue and pruritus were significantly and exclusively related to the presence of florid interlobular bile duct lesions (p<0.01 and p<0.02, respectively). The only laboratory parameter associated with the presence of interlobular bile duct florid lesion was IgM level. The most discriminant biochemical test for interlobular bile duct paucity was gamma glutamyltranspeptidase activity. The degree of severity of both lymphocytic hepatocellular piecemeal necrosis and lobular inflammation and necrosis was mainly associated with increased gammaglobulin and IgG levels and to a lesser extent with increased IgM and aspartate aminotransferase levels. The extent of fibrosis was mainly associated with gammaglobulin levels and to a lesser degree with serum albumin, bilirubin and IgG levels. CONCLUSIONS: Symptoms and biochemistries classically used to assess primary biliary cirrhosis reflect in part the degree of severity of the main elementary histological lesions. We propose that the picture of primary biliary cirrhosis results from the clinical and biochemical expression of three distinct processes, e.g., bile duct inflammation and destruction, parenchymal inflammation and necrosis, and fibrosis. The various combinations of these processes may explain why the spectrum of primary biliary cirrhosis varies from typical primary biliary cirrhosis to mixed type of primary biliary cirrhosis and autoimmune hepatitis and suggests that the response to therapies may depend on the predominance of each process in a given patient.

Adrenal Cortex Hormones↗
PubMed1999

Effects of amino acids on bile acid-dependent and independent bile flow in the isolated perfused rat liver.

BACKGROUND/AIMS: Conflicting data on the effects of amino acids on biliary function led us to investigate their interaction with taurocholate in the perfused rat liver model. METHODS: To investigate the influence of amino acids on the bile acid-independent component of bile flow, 12 livers were perfused with (n = 6) and without (n = 6) amino acid addition from t30 min. For the study of bile acid-dependent bile flow, 24 livers were perfused under 8 experimental conditions according to the perfusate taurocholate concentration (12.5, 25, 37.5 or 50 microM) and whether amino acids were or were not added from t30 min. RESULTS: In the absence of taurocholate, amino acids induced a 40% (p<0.01) decrease in bile flow together with an increase in hepatic water content (17.8%, p< 0.05). Thus, amino acids exert an inhibitory effect on bile acid-independent bile flow despite the postulated cell swelling-dependent increase in bile flow. When livers were perfused at various taurocholate concentrations, amino acids induced, in addition to their inhibitory effect on bile acid-independent bile flow, a significant increase in taurocholate apparent choleretic activity (13.2 microl/micromol vs. 10.6 microl/micromol; p = 0.05), while taurocholate intrinsic clearance was significantly decreased (4.5+/-1.2 ml x min(-1) x g(-1) vs. 6.1+/-1.3 ml x min(-1) x g(-1); p<0.01). CONCLUSIONS: These data suggest that at physiological bile acid concentrations amino acids exert an inhibitory effect on both bile acid-dependent and- independent bile flow, whereas at higher taurocholate concentrations this inhibitory effect disappears, probably because of cell swelling-dependent mechanisms.

Amino Acids↗
PubMed1999

A randomized trial of ribavirin and interferon-alpha vs. interferon-alpha alone in patients with chronic hepatitis C who were non-responders to a previous treatment. Multicenter Study Group under the coordination of the Necker Hospital, Paris, France.

BACKGROUND/AIM: Fifty percent of patients infected with hepatitis C virus (HCV) show no response to alpha-interferon, and no alternative therapy has thus far proven to be effective. Therapeutic combination with ribavirin and alpha-interferon has shown promising results in naive patients and in relapsers, but based on limited series, it was reported to be inefficient in non-responders. The aim of our study was therefore to explore and compare, in a randomized trial, the tolerance and potential efficacy of alpha-interferon alone with a sequential combination of ribavirin and the same alpha-interferon regimen in those patients. METHODS: Sixty-four non-responder patients were randomized in the alpha2b-interferon group (a 6-month course at a dosage of 6 MU followed by a 6-month course of 3 MU three times weekly subcutaneously) and 62 in the "combination" group (sequential combination of the same alpha2b-interferon therapy preceded by a 2-month course of ribavirin which was then associated for 2 months with alpha2b-interferon at a daily dosage of 1.0 or 1.2 g). RESULTS: Treatment withdrawal was necessary for six patients from the alpha-interferon and eight patients from the combination group. Normalization of aminotransferase activities was significantly more frequent after the 4-month course of ribavirin with 2 months of interferon than after 2 months of interferon alone (52.8 vs. 26.2%, p<0.01), but this difference was not maintained after ribavirin withdrawal. Disappearance of serum HCV RNA (PCR) was significantly more frequent at the end of treatment in the combination group (24.5 vs. 7.7%, p=0.02), but did not differ 6 months after the end of therapy (9.8 and 8.3%, respectively). The long-term response was not associated with liver status (cirrhosis vs. absence of cirrhosis) or genotype. Mean viremia was significantly lower in long-term responders than in non-responders or relapsers in both groups (p<0.001 for the interferon group and p<0.05 for the combination group), but the large extent of viral load precluded reliable prediction. The pre- and post-treatment hepatitis activity index did not differ between the two groups. While a crude histopathological improvement in the hepatitis activity index for a given patient was more frequently observed in the combination group (69.2 vs. 35.9%, p<0.01), improvement as defined by a decrease of at least 2 in the hepatitis activity index was significant only for lobular necrosis and degeneration. CONCLUSIONS: This study demonstrates the efficacy of the combination of ribavirin/alpha-interferon in non-responders. Indeed, (i) it is fairly tolerated; (ii) it increases the rate of the initial biological response, and of the virological response by decreasing breakthrough, though this benefit is not sustained; and (iii) it induces a significant histological improvement in necrosis. A simultaneous and prolonged combination of ribavirin/alpha-interferon should be further evaluated in non-responders.

Antiviral Agents↗
PubMed1999

Direct cytotoxicity of hypoxia-reoxygenation towards sinusoidal endothelial cells in the rat.

AIMS/BACKGROUND: Sinusoidal endothelial cells are the primary target of ischemia-reperfusion injury following liver preservation. The present study was undertaken to examine the susceptibility of sinusoidal endothelial cells to hypoxia-reoxygenation and the potential role of oxygen free radicals in the induction of cell injury. METHODS: Sinusoidal endothelial cells were isolated from rat liver. After 2 3 days of primary culture, the cells were exposed to hypoxia (N2/CO2 95/5) for 120 min and reoxygenation (O2/CO2 95/5) for 90 min. Control cells were exposed to hypoxia alone, to 95% O2 alone or were maintained under normoxic conditions. Human umbilical vein endothelial cells were used as a model of vascular endothelial cells and submitted to the same protocol. Cell viability and lipid peroxidation were assessed by LDH leakage and malondialdehyde production, respectively. In order to test the potential role of xanthine oxidase and mitochondrial dysfunction in cell injury, the cells were treated with allopurinol and potassium cyanide (KCN) respectively. RESULTS: The different gaseous treatments did not affect LDH leakage in human umbilical vein endothelial cells. In sinusoidal endothelial cells, the sequential hypoxia-reoxygenation caused a significant increase in LDH release, malondialdehyde production and xanthine oxidase activity while hypoxia alone had no effect except on xanthine oxidase activity. Allopurinol inhibited xanthine oxidase without preventing cell injury or lipid peroxidation in this latter cell type. CONCLUSIONS: The results suggest that sinusoidal endothelial cells, as opposed to vascular endothelial cells, are susceptible to a direct cytotoxic effect of hypoxia-reoxygenation. This effect occurs in combination with an increase in xanthine oxidase activity and lipid peroxidation, although cell injury is mediated at least in part by mechanisms independent of xanthine oxidase such as mitochondrial dysfunction.

Animals↗
PubMed1998

Endothelin-1 is synthesized and inhibits cyclic adenosine monophosphate- dependent anion secretion by an autocrine/paracrine mechanism in gallbladder epithelial cells.

Ion and fluid transport across the biliary epithelium contributes to bile secretion. Since endothelin (ET)-1 affects ion transport activities and is released by human gallbladder- derived biliary epithelial cells in primary culture, we examined the expression of ET peptides and ET receptors and the influence of ET-1 on ion transport in this epithelium ex vivo. In freshly isolated gallbladder epithelial cells, preproET-1, -2, and -3 mRNAs were detected by reverse transcription PCR and ET-1 isopeptide was identified by chromatography. The cells also displayed ET receptor mRNAs and high-affinity binding sites for ET-1, mostly of the ETB type. Electrogenic anion secretion across intact gallbladder mucosa was stimulated by forskolin, secretin, and exogenous ATP, as assessed by short-circuit current (Isc) increases in Ussing-type chambers. ET-1 inhibited forskolin- and secretin-induced changes in Isc, without affecting baseline Isc or ATP-induced changes. Accordingly, ET-1 significantly reduced the accumulation of intracellular cAMP elicited by forskolin and secretin in the epithelial cells, and this effect was abolished by pertussis toxin. This is the first evidence that ET-1 is synthesized and inhibits, via a Gi protein-coupled receptor, cAMP-dependent anion secretion in human gallbladder epithelium, indicating a role in the control of bile secretion by an autocrine/paracrine mechanism.

Anions↗
PubMed1998

Determinants of outcome of compensated hepatitis C virus-related cirrhosis.

The aim of this study was to assess the incidence of decompensation (ascites, jaundice, variceal bleeding, and encephalopathy), hepatocellular carcinoma (HCC) and death or liver transplantation in patients with compensated hepatitis C virus (HCV)-related cirrhosis, taking into account the viral genotype and interferon (IFN) therapy. Between 1989 and 1994, 668 patients with no clinical evidence of decompensation were referred to our department for liver biopsy because of positivity for anti-HCV antibodies and elevated aminotransferase activity; 103 of these patients had cirrhosis. The median follow-up was 40 months. Fifty-nine patients were treated with IFN for a mean duration of 11+/-6 months; 3 (5%) had a prolonged biochemical and virological response. Baseline characteristics of IFN-treated and untreated patients were not significantly different. HCV genotypes (InnoLiPa) were predominantly 1b (48%) and 3a (20%). During follow-up, complications of cirrhosis occurred in 26 patients, HCC in 11 patients, and decompensation not related to HCC in 19 patients. Sixteen patients died, 94% of liver disease. Three patients were transplanted for liver failure. The 4-year risk of HCC was 11.5% (annual incidence 3.3%) and that of decompensation was 20%. Survival probability was 96% and 84% at 2 and 4 years, respectively. In multivariate analysis, the absence of IFN therapy was the only independent factor predictive both for HCC and decompensation. A low albumin level at entry and the absence of IFN therapy were the two independent factors predictive of death or liver transplantation. Probability of survival at 2 and 4 years was significantly different between IFN-treated and untreated patients (respectively 97% and 92% vs 95% and 63%, P < .0001). In conclusion, in patients with compensated HCV-related cirrhosis: 1) complications of cirrhosis are frequent, whatever the viral genotype; and 2) the severity of cirrhosis and the absence of IFN therapy are independently predictive of bad outcome.

Adult↗
PubMed1998

Primary biliary cirrhosis-autoimmune hepatitis overlap syndrome: clinical features and response to therapy.

The association of primary biliary cirrhosis (PBC) and autoimmune hepatitis (AIH) is thought to be rare, and its optimal treatment is unknown. Of 130 consecutive patients with a diagnosis of PBC, we identified 12 cases (9.2%) of overlap syndrome (10 females, 2 males; median age, 50 years) strictly defined by the presence of at least two of the three recognized biochemical, serological, and histological criteria of each disease. One patient had initially pure PBC and developed AIH characterized by a flare of alanine transaminase (ALT) (1,330 IU/L; N < 35), elevated immunoglobulin G (IgG) (42 g/L; N < 14.0), and presence of anti-smooth muscle antibodies (ASMA) after 20 months of ursodeoxycholic acid (UDCA) therapy. A complete clinical and biochemical remission was achieved under combination of corticosteroids and UDCA. Eleven patients had features of both diseases at presentation: high serum levels of alkaline phosphatase (AP) (median: 280 IU/L; N < 100), ALT (140 IU/L), and IgG (30.8 g/L), presence of mitochondrial antibodies (n = 9) or ASMA (n = 9), florid bile duct lesions (n = 8), and moderate or severe periportal or periseptal lymphocytic piecemeal necrosis (n = 11). UDCA (13-15 mg/kg/d) given alone in 5 patients induced a significant decrease in biochemical cholestasis but not in ALT levels, and liver fibrosis progressed in 3 patients. Corticosteroids given alone in 6 patients induced a significant decrease in ALT, IgG, and AP levels, but none had a biochemical normalization. The patients with persistently abnormal liver tests under either UDCA or corticosteroids received both UDCA and corticosteroids. A further marked biochemical improvement was observed, and all patients became asymptomatic. We conclude that, in patients with PBC: 1) overlap syndrome with AIH is not rare; 2) flares of AIH may occur either spontaneously or under UDCA; and 3) combination of UDCA and corticosteroids is required in most patients to obtain a complete biochemical response. Overlap syndrome may represent an important and unrecognized cause of resistance to UDCA in patients with PBC.

Adrenal Cortex Hormones↗
PubMed1997

Risk factors for cirrhosis in patients with chronic hepatitis C virus infection: results of a case-control study.

The role of the viral genotype, especially genotype 1b, in the severity of liver injury induced by chronic hepatitis C virus (HCV) infection is unclear, probably because of confounding factors such as the date and mode of contamination. Host genetic or environmental factors such as heterozygous MZ alpha1-antitrypsin deficiency or alcoholism, could also be potential risk factors for the development of cirrhosis. The aim of this study was to compare the prevalence of genotypes, alpha1-antitrypsin phenotype, past hepatitis B virus infection, and alcohol consumption in cirrhotic and noncirrhotic patients with chronic hepatitis C. We conducted a case-control study comparing 84 consecutive cirrhotic patients with chronic hepatitis C (cases) with 84 noncirrhotic patients with chronic hepatitis C (controls) selected from a cohort of 464 patients hospitalized during the same period. Controls were paired with cases according to age, sex, risk factors, and date of infection. HCV genotypes were determined using the InnoLiPA technique (Innogenetics, Zwijnaarde, Belgium) and classified according to the method of Simmonds. Patients were divided in three groups according to alcohol consumption: <30 g/d (light), 30 to 80 g/d (moderate), and >80 g/d (heavy). Cirrhotic and noncirrhotic patients were not significantly different in terms of genotype distribution (1a/1b/2a/3a/others/undetermined: 10/48/7/17/0/2 versus 11/43/10/10/5/5), alpha1-antitrypsin phenotype distribution (MM/MS/MZ: 84%/14%/2% vs. 87%/11%/2%, respectively), and prevalence of antibody to hepatitis B core antigen positivity (29% vs. 23%). Alcohol consumption was significantly different between cases and controls (L/M/H: 58%/27%/16% vs. 76%/15%/9%, respectively; P < .05). Two conclusions regarding patients with chronic hepatitis C virus infection can be drawn from this study: 1) viral genotype, especially 1b, past hepatitis B virus infection, and heterozygous MZ alpha1-antitrypsin deficiency are not risk factors for cirrhosis; and 2) alcohol consumption, even moderate, is a risk factor for cirrhosis.

Adult↗
PubMed1997

Circulating albumin messenger RNA in hepatocellular carcinoma: results of a multicenter prospective study.

The presence of circulating tumor cells might be an indicator of hematogenous spread of tumor cells leading to extrahepatic metastasis. Messenger RNA (mRNA) expression of human albumin, as a liver specific cell marker, has been proposed for this purpose in hepatocellular carcinoma. We conducted a multicenter prospective study in 101 patients with biopsy-proven hepatocellular carcinoma followed-up every 3 months for 1 year or until death. At entry into the study, albumin mRNA was detected in the blood by reverse transcription-polymerase chain reaction (RT-PCR). At entry into the study, 45% of the patients had a positive albumin mRNA test, 53% a single tumor, 16% a portal or venous hepatic thrombosis, and 16% had proven metastasis. After 1 year, there was no significant difference in survival of patients with positive or negative albumin mRNA at entry (P = .16, log-rank test). When patients with metastasis at entry were excluded, again survival did not differ between the two groups (P = .20). Independent prognostic factors of survival were radical therapeutic procedures, metastasis, number of tumors, Child-Pugh score, and thrombosis, but not the albumin mRNA test. Taking the presence of metastasis as a reference, the specificity of the test was 56%, its sensitivity 50%, and its negative predictive value 85%. The present study shows that circulating albumin mRNA detected by means of RT-PCR fails to provide significant information in the diagnosis and prognosis of hepatocellular carcinoma. Further studies are needed to determine whether the use of specific tumor markers could have clinical relevance in this setting.

Adult↗
PubMed1997

Combined analysis of randomized controlled trials of ursodeoxycholic acid in primary biliary cirrhosis.

BACKGROUND & AIMS: Long-term ursodeoxycholic acid (UDCA) therapy slows the progression of primary biliary cirrhosis. This study examined the effect of UDCA therapy on survival free of liver transplantation in a large group of patients. METHODS: Data from three clinical trials were combined in which patients with primary biliary cirrhosis were randomly assigned to receive UDCA (n = 273) or placebo (n = 275). After 2 years, patients from French and Canadian studies received UDCA for up to 2 years. Patients from the American study remained on their assigned treatment for up to 4 years. RESULTS: Survival free of liver transplantation was significantly improved in the patients treated with UDCA compared with the patients originally assigned to placebo (P < 0.001; relative risk, 1.9; 95% confidence interval, 1.3-2.8). Subgroup analyses showed that survival free of liver transplantation was significantly improved in medium- and high-risk groups (serum bilirubin level, 1.4 to 3.5 or > 3.5 mg/dL; P < 0.0001 and P < 0.03, respectively) and histological stage IV subgroup (P < 0.01). CONCLUSIONS: Long-term UDCA therapy improves survival free of liver transplantation in patients with moderate or severe disease. An effect in patients with mild disease is probably not found because they do not progress to end-stage disease in 4 years.

Adult↗
PubMed1997

Evidence for a deficiency of interferon response in mononuclear cells from hepatitis C viremic patients.

BACKGROUND/AIMS: The pathophysiology of chronic hepatitis C and the mechanisms of resistance to interferon alpha 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 TNF alpha and IL1 beta. 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 TNF alpha or IL1 beta 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.

2',5'-Oligoadenylate Synthetase↗
PubMed1997

Bile acid inhibition of interferon activity in human lymphocytes: no evidence of oxidative stress.

Cholestasis and bile acids are two factors involved in resistance to interferon therapy in patients with chronic hepatitis C. As bile acids inhibit the biological activity of this cytokine in vitro and are capable of generating oxidative stress in hepatocytes, we investigated the potential involvement of such a mechanism in human lymphocytes. Thus, we evaluated (a) the effects of bile acids (0-200 mumol L-1) on lymphocyte reduced glutathione content and malondialdehyde production and (b) the ability of antioxidants to prevent the inhibitory effect of chenodeoxycholic acid on interferon-induced lymphocyte 2',5'-oligoadenylate synthetase activity, an index of the biological activity of interferon. We found that treatment of lymphocytes with bile acids for 24 h did not induce malondialdehyde release or significantly modify cellular reduced glutathione content. Synthetic precursors of glutathione (N-acetylcysteine and S-adenosylmethionine) and antioxidants (superoxide dismutase and catalase) had no preventive influence on the inhibitory effect of chenodeoxycholic acid on interferon-induced 2',5'-oligoadenylate synthetase activity. These negative results do not provide evidence for the use of glutathione precursors in cholestatic conditions associated with viral diseases.

2',5'-Oligoadenylate Synthetase↗