Activity of the interferon-induced 2',5'-oligoadenylate synthetase in patients with chronic hepatitis C

Modulation of the type I interferon pathways by culture-adaptive hepatitis C virus core mutants

Hepatitis C virus (HCV) often establishes a persistent infection that leads to chronic liver diseases. The viral core protein modulates various cellular activities involved in this process. We found two mutations, K23E and V31A, in the core gene of the transfected HCV JFH-1 genome, which had been replicated for a prolonged period. The mutant viruses escaped immunochemical detection by a core-specific antibody and demonstrated enhanced RNA replication and protein expression, compared to the parental virus. The mutant core proteins bound less tightly than the parental type core to the DEAD-box RNA helicase DDX3 and attenuated the TBK1-mediated activation of interferon-related promoters. These results suggest a mechanism by which the viruses adapt to attenuate cellular antiviral activity and to establish persistent infection.

Single nucleotide polymorphism at exon 7 splice acceptor site of OAS1 gene determines response of hepatitis C virus patients to interferon therapy

BACKGROUND AND AIM

Response to interferon therapy and disease progression in hepatitis C virus (HCV) infected patients differs among individuals, suggesting a possibility of a contribution of host genetic factors. 2'-5'-oligoadenylate synthetase 1 (OAS1), an important component of the innate immune system with a proven antiviral function, may therefore have a relationship with the response to interferon therapy and clinical course of HCV disease. Our aim was to determine the frequency of single nucleotide polymorphism (SNP) at exon 7 splice acceptor site (SAS) of the OAS1 gene in relation to the interferon response and status of HCV infection.

METHODS

A 203 bp fragment containing exon 7 SAS was amplified in 70 HCV chronic patients and 50 healthy controls. SNP was examined using restriction fragment length polymorphism (RFLP) genotyping method. Correlations of SNP genotypes with response to interferon and clinical status of patients were statistically analyzed.

RESULTS

There was an increasing trend of response from AA to AG to GG genotypes (P = 0.007). Genotype AA was associated with non-response to interferon and higher degree of liver fibrosis (P = 0.05). Multivariate analysis showed this SNP as independent and a significant determinant of the outcome of interferon therapy (odds ratio 4.913 [95% confidence interval 1.365-8.2], P = 0.006).

CONCLUSIONS

This is the first study to show a significant association between the functional SNP at exon 7 SAS of OAS1 gene and the viral response to interferon in chronic HCV patients. Patients with AA genotype were associated with progressive HCV disease and viral resistance to interferon therapy. This OAS SNP is a potential bio-marker to predict IFN response in chronic hepatitis C patients.

Danoprevir monotherapy decreases inflammatory markers in patients with chronic hepatitis C virus infection

Danoprevir is a potent and selective direct-acting antiviral agent that targets the protease activity of hepatitis C virus (HCV) NS3/4A. This agent results in a significant rapid decline in HCV RNA levels when it is used in monotherapy. The present study evaluated whether plasma concentrations of the inflammatory markers gamma interferon-inducible protein 10 (IP-10) and neopterin or the interferon-stimulated gene product 2'-5'-oligoadenylate synthetase (OAS-1) were correlated with the plasma HCV RNA concentration before or during 14-day danoprevir monotherapy. In contrast to pegylated interferon and ribavirin treatment, a higher baseline IP-10 concentration was positively correlated with a greater first-phase HCV RNA decline upon danoprevir administration. Changes in the IP-10 plasma concentration during danoprevir administration were also associated with categorical changes in HCV RNA concentration at days 7 and 14. The neopterin concentration appeared to be moderately decreased during danoprevir administration, although these changes were not statistically significant. However, changes in neopterin concentration showed a statistically significant correlation with changes in IP-10 concentration. Considerable variation in the OAS-1 concentration was observed before and during treatment, including in patients treated with placebo and/or patients with minimal virologic response. Overall, these results suggest that effective treatment with a direct-acting antiviral agent may reduce hepatic inflammation and that first-phase HCV RNA decline during treatment with an NS3/4A protease inhibitor is more robust in patients with high baseline IP-10 concentrations.

Differential expression of interferon-induced microRNAs in patients with chronic hepatitis C virus infection treated with pegylated interferon alpha

There have been reports of in-vitro interferon (IFN)-mediated antiviral activity against the hepatitis C virus (HCV) through microRNAs (miRNAs). The main aim of this study was to evaluate the expression of several miRNAs (miR-1, miR-30, miR-128, miR-196, miR-296) in peripheral blood mononuclear cells (PBMCs) from healthy individuals after in vitro IFN-treatment and in PBMCs from patients with chronic hepatitis C (CHC) before and 12 hours after the first injection of pegylated IFN alpha. We demonstrated that expression of these miRNAs could be recorded in PBMCs collected from healthy individuals before and after in-vitro IFN alpha treatment. Our analysis revealed that the levels of expression of all miRNAs investigated in patients with CHC were different to those in healthy individuals. When levels of the miRNAs were measured 12 hours after the first IFN injection, increases in expression levels of IFN-induced miRNAs were observed in 25-50% of patients, depending on the type of miRNA examined. No correlations were observed between HCV viral load, alanine aminotransferase status and expression of miRNA. Together these findings suggest that: (i) IFN alpha in-vitro treatment of PBMCs leads to a transcriptional induction of all miRNAs investigated; (ii) miRNAs can be induced differentially by IFN treatment in patients with HCV. Given the importance of miRNAs in defending the host against virus infections, it is possible that IFN-induced miRNAs may represent an important determinant of the clinical outcome of IFN therapy in HCV infection.

Polymorphism of OAS-1 determines liver fibrosis progression in hepatitis C by reduced ability to inhibit viral replication

BACKGROUND

Progression of disease after hepatitis C virus (HCV) infection differs among individuals, indicating a possibility of participation of host genetic factors. 2'-5'-oligoadenylate synthetase 1 (OAS-1), an important component of the innate immune system, has an antiviral function, and may therefore have a certain relationship with progression of disease.

AIM

To evaluate single nucleotide polymorphisms (SNPs) of OAS-1 and its relationship with the disease status of HCV infection.

METHODS

Six SNPs of OAS-1 were selected and examined in 409 Japanese patients with chronic HCV infection using the TaqMan PCR genotyping method. The relationship of SNP genotypes and clinical manifestations of patients was analysed. Then, a pair of OAS-1-expression plasmids mimicking the clinical-related SNPs were created and transfected into liver cells carrying the HCV subgenomic replicon or the full-length genome, JFH1, and HCV replication after transfection was compared.

RESULTS

Patients with genotypes A/A, A/G and G/G of an SNP of OAS-1 at the exon 3 of its coding sequence were at gradient increased risks of suffering from higher serum alanine aminotransferase (P<0.001) and aspartate aminotransferase (P=0.001), higher degree of liver fibrosis (P=0.010) and higher presence of liver cirrhosis (P=0.001). By multivariate logistic regression analysis, genotype G/G was an independent factor associated with cirrhosis (P=0.013, odds ratio 3.11, 95% confidence interval 1.27-7.63). In liver cells, OAS-1 with the G allele showed lower ability to inhibit virus replication than OAS-1 with the A allele (P=0.004).

CONCLUSIONS

The SNP of OAS-1 at the exon 3 of its coding sequence was associated with progression of disease in Japanese patients with HCV infection.

Pharmacodynamics of peginterferon alpha-2a and peginterferon alpha-2b in interferon-naïve patients with chronic hepatitis C: a randomized, controlled study

BACKGROUND

Peginterferon alpha-2a and alpha-2b, the two commercially available pegylated interferons, have different pharmacokinetic properties that produce differing abilities to suppress replication of the hepatitis C virus.

AIM

To compare the pharmacodynamics of peginterferon alpha-2a and peginterferon alpha-2b in interferon-naive patients with chronic hepatitis C.

METHODS

Patients were randomized to receive peginterferon alpha-2a, 180 microg (n = 10) or peginterferon alpha-2b 1.0 microg/kg (n = 12) once weekly. The enzymatic activity of 2'5'-oligoadenylate synthetase and levels of neopterin and beta(2)-microglobulin were measured at baseline and at 24, 48, 120 and 168 h.

RESULTS

Oligoadenylate synthetase activity and serum neopterin and beta(2)-microglobulin concentrations did not differ significantly between the two patient groups at any time point, nor was there a significant correlation between the serum area under the concentration-time curve of either peginterferon and the area under the concentration-time curve for 2',5'-oligoadenylate synthetase, neopterin and beta(2)-microglobulin. The area under the concentration-time curves calculated for these three markers did not correlate with body mass index stratified at <25 and >or=25 kg/m(2) for either peginterferon.

CONCLUSIONS

Despite pharmacokinetic differences between peginterferon alpha-2a and peginterferon alpha-2b, the pharmacodynamic profiles of the two formulations appear to be comparable.

IRES complexity before IFN-alpha treatment and evolution of the viral load at the early stage of treatment in peripheral blood mononuclear cells from chronic hepatitis C patients

At the early stage of treatment, IFN alpha-2a induces inhibition of HCV replication. The viral load reflects mainly the degradation rate of the viruses. However, differences in the behavior of the viral population depend on changes, which occurred in the HCV-IRES genome. In this study, cloning and sequencing strategies permitted the generation of a large number of IRES sequences from the PBMCs of 18 patients (5 women, 13 men) with chronic hepatitis C. The HCV IRES appeared to be highly conserved structurally. However, some variability was found between the different isolates obtained: 467 substitutions with a median of 7 variants/patients. No relationship was observed between pre-treatment IRES complexity and the viral load at the beginning. However, on review of the evolution of viral load in the PBMCs during the first 3 days of IFN alpha-2a treatment, patients could be classified into two groups: Group 1, in which the viral population continued to replicate and Group 2, in which the viral load decreased significantly (P = 0.01727). Positioning of the mutations on the predicted IRES secondary structure showed that the distribution of the mutations and their apparition frequency were different between the two groups. At the early stage of treatment, IFN alpha-2a was efficient in reducing the viral replication in a significant number of patients; mechanisms of response might affect the virus directly. However, pre-treatment genomic variations observed in the 5'NCR of HCV were not a parameter of a later response to antiviral therapy in chronic hepatitis C patients. (244)

Clinical utility of 2',5'-oligoadenylate synthetase activity measurement: using whole blood as a highly sensitive method to detect the effects of IFN

Research progress on the pleiotropic effects of interferons (IFN) has thus far required detecting responses by weak IFN signals. The activity of 2',5'-oligoadenylate synthetase (2-5OAS) is a valuable indicator in the prognosis and IFN treatment of patients with viral diseases such as hepatitis B and C. Although serum samples generally are used to measure enzyme activity, their values depend on the exact conditions under which blood is stored and the degree of haemolysis that occurs during blood drawing or serum separation. This study presents an improved method of evaluating 2-5OAS activity by using whole blood samples containing heparin, which are frozen and then thawed, instead of serum samples. This method is more reliable, convenient, and 50-100 times more sensitive than the conventional methods of measuring serum 2-5OAS activity. The reliability and sensitivity of this improved method enables detection of the effects of low doses of oral IFN administration or changes in the IFN and cytokine system by infection or autoimmune diseases.

Undetectable phospho-STAT1 in peripheral blood mononuclear cells from patients with chronic hepatitis C who do not respond to interferon-alpha therapy

BACKGROUND

Recent studies have suggested that phosphorylated signal transducers and activators of transcription 1 (STAT1) plays an important role in interferon (IFN)-mediated biological functions, including antiviral activity. Moreover, it has been demonstrated that suppressors of the cytokine signal 1 (SOCS1) negatively regulates IFN activities.

AIMS

To investigate the involvement of phospho-STAT1 in the response to IFN-alpha therapy in patients with chronic hepatitis C and to evaluate the negative regulatory effect of SOCS1 on STAT1 activation.

METHODS

Sixty-five patients with chronic hepatitis C and 25 healthy subjects were enrolled. Twenty-five of the patients had never been treated with IFN-alpha therapy (naive), while the remaining 40 patients had. The IFN-treated patients were divided into sustained responders (SRs) or non-responders (NRs) on the basis of their response to the antiviral therapy. Peripheral blood mononuclear cells (PBMCs) were obtained from each patient and control, and were either stimulated with IFN-alpha or left unstimulated. Total STAT1, phospho-STAT1 and SOCS1 were revealed by means of Western blot.

RESULTS

Total STAT1 was equally expressed in unstimulated and stimulated PBMCs from all patients and controls. One hundred percent of the stimulated PBMCs from healthy controls and SRs, 96% from naive subjects, and 30% from NRs showed detectable phospho-STAT1. By contrast, 70% of the stimulated PBMCs from NRs showed undetectable phospho-STAT1.

CONCLUSIONS

We have demonstrated that phospho-STAT1 proteins in 70% of patients with chronic hepatitis C who do not respond to IFN treatment are undetectable, which suggests that this protein may be involved in the mediation of IFN sensitivity. The down-regulation of the Jak-STAT pathway because of SOCS1 expression may be one of the possible underlying mechanisms involved in resistance to IFN.

Effects of the hepatitis C virus core protein on innate cellular defense pathways

The hepatitis C virus (HCV) core protein is thought to contribute to HCV pathogenesis through its interaction with various signal transduction pathways. In this study, we explored the interaction of the core protein with innate defense pathways (interferon [IFN] regulatory factor [IRF], Jak-Stat, and inducible nitric oxide synthase [iNOS]) in HeLa and Huh7 human cell lines. Expression of a patient-derived genotype 1b core protein activated human IRF-1 and guanylate-binding protein-2 (GBP-2) promoters, induced IRF-1 mRNA, but failed to induce IRF-3 phosphorylation. HCV core protein caused dose-dependent induction of the IFN-beta promoter and IFN-beta mRNA but not the IFN-alpha1 and IFN-alpha4 promoters. In the presence of IFN-alpha, core expression was associated with increased IFN-stimulated gene factor 3 (ISGF3) binding to the IFN-stimulated response element (ISRE) and tyrosine phosphorylation of Stat1. Core expression resulted in dose-dependent activation of the ISRE and gamma activated sequence (GAS) promoters, in both the absence and the presence of either IFN-alpha or IFN-gamma. Core stimulated the human iNOS promoter and induced iNOS protein. The data indicate that HCV core can modulate IRF, Jak-Stat, and iNOS pathways and suggest mechanisms by which core could affect HCV persistence and pathogenesis.

Effect of in vitro interferon-beta administration on hepatitis C virus in peripheral blood mononuclear cells as a predictive marker of clinical response to interferon treatment for chronic hepatitis C

AIM: To test whether in vitro incubation of peripheral blood mononuclear cells (PBMC) with interferon (IFN) could efficiently decrease hepatitis C virus-RNA (HCV-RNA) amount and to analyze whether this effect was associated with clinical response to IFN.

METHODS: Twenty-seven patients with histologically proven chronic hepatitis C were given intravenous administration of 6 million units (MU) IFN-β daily for 6 weeks followed by three times weekly for 20 weeks. PBMC collected before IFN therapy were incubated with IFN-β and HCV-RNA in PMBC was semi-quantitatively determined.

RESULTS: Twenty-five patients completed IFN therapy. Eight patients (32%) had sustained loss of serum HCV-RNA with normal serum ALT levels after IFN therapy (complete responders). HCV-RNA in PBMC was detected in all patients, whereas it was not detected in PBMC from healthy subjects. In vitro administration of IFN-β decreased the amount of HCV-RNA in PMBC in 18 patients (72%). Eight of these patients obtained complete response. On the other hand, none of the patients whose HCV-RNA in PBMC did not decrease by IFN-β was complete responders. Multiple logistic regression analysis revealed that the decrease of HCV-RNA amount in PBMC by IFN-β was the only independent predictor for complete response (P < 0.05).

CONCLUSION: The effect of in vitro IFN-β on HCV in PBMC reflects clinical response and would be taken into account as a predictive marker of IFN therapy for chronic hepatitis C.

Novel differential gene expression in human cirrhosis detected by suppression subtractive hybridization

Pathogenic molecular pathways in cirrhotic liver diseases such as hepatitis C virus (HCV), autoimmune hepatitis (AIH) and primary biliary cirrhosis (PBC) are poorly characterized. Differentially expressed genes are often important in disease pathogenesis. Suppression subtractive hybridization (SSH) is a genome-wide approach that enriches for differentially expressed mRNA transcripts. We aimed to make novel observations of differential gene expression in cirrhosis using SSH combined with quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). Liver transcriptomes in HCV cirrhosis, AIH cirrhosis, PBC, and nondiseased liver tissue were examined by SSH. Resulting complementary DNA (cDNA) clones were rescreened for differential expression by dot-blot hybridization and then sequenced. Selected gene expression was quantified by real-time RT-PCR. Following SSH, 694 clones were rescreened for differential gene expression, of which 145 were sequenced and found to derive from 89 different genes. Seven clones were homologous only with expressed sequence tag (EST) sequences encoding genes having no known function. Up-regulated expression of four genes was confirmed by real-time RT-PCR: transmembrane 4 superfamily member 3 (tetraspanin CO-029) in all forms of cirrhosis, hedgehog interacting protein (HIP) in AIH cirrhosis and chitinase 3-like-1 (HC gp-39 or ykl-40) and arginine-glutamic acid repeat (RERE) in HCV cirrhosis. RERE gene polymorphisms and splice variants were observed in all tissues examined. Tetraspanin CO-029 up-regulation was primarily localized to bile ductular cells. In conclusion, novel observations of differential gene expression in human cirrhosis were made using SSH as the primary discovery tool. In particular, further studies of the RERE gene and its products in HCV associated liver disease are warranted.

Polymorphisms in interferon-induced genes and the outcome of hepatitis C virus infection: roles of MxA, OAS-1 and PKR

Interferon stimulates the expression of a number of genes encoding enzymes with antiviral activities, including myxovirus resistance-1 (MxA), 2-5-oligoadenylate synthetase 1 (OAS-1) and double-stranded RNA-dependent protein kinase (PKR). We examined whether polymorphisms in these genes influenced the outcome of hepatitis C virus (HCV) infection. We observed a lower frequency of the GG genotype at position -88 in the MxA gene promoter in self-limiting HCV infection (OR=0.56; 95% CI: 0.35-0.8; P=0.010) and in nonresponders to therapy (OR=0.49; 95% CI: 0.25-0.95; P=0.020). This genotype predominantly influenced the outcome of treatment in patients with viral genotype 1 (OR=0.22 95% CI: 0.07-0.67; P=0.002). A polymorphism in the 3'-untranslated region of the OAS-1 gene was associated with outcome of infection (GG genotype less frequent in self-limiting infection: OR=0.43; 95% CI: 0.21-0.86; P=0.010). A polymorphism at position -168 in the promoter region of the PKR gene was associated with self-limiting infection (CT genotype: OR=2.75; 95% CI: 1.45-5.24; P=0.002). Further associations were found with a CGG trinucleotide repeat in the 5'UTR region of the PKR gene. Polymorphisms in the interferon-induced genes, MxA, OAS-1 and PKR appear thus associated with HCV outcome.

Quantitative analysis of p40/p46 and p69/p71 forms of 2',5'-oligoadenylate synthetase mRNA by competitive PCR and its clinical application

BACKGROUND

2',5'-Oligoadenylate synthetases (2-5AS) are type I interferon (IFN)-induced proteins with antiviral capacity. Three major forms of 2-5AS with distinct enzymatic activities have been described in IFN-treated human cells. We measured distinct forms of 2-5AS mRNA to analyze the relationship with its enzymatic activity and response to IFN therapy in chronic hepatitis C.

METHODS

We established a method to quantify p40/p46 and p69/p71 forms of 2-5AS mRNA by use of reverse transcription followed by competitive PCR. The 2-5AS mRNA concentrations were measured in peripheral blood mononuclear cells from 40 patients with chronic hepatitis C and 28 control individuals.

RESULTS

Reconstitution experiments and comparison with Northern blot analyses revealed that our method accurately and linearly quantified 2-5AS mRNA. 2-5AS mRNA concentrations and 2-5AS enzymatic activity were correlated (P <0.03). Our data demonstrated a correlation in 2-5AS mRNA between p40/p46 and p69/p71 (P <0.02), indicating a similar regulation of the expression of these genes. Our data also demonstrated that pretreatment concentrations of 2-5AS mRNA correlated with responses to IFN therapy in chronic hepatitis C.

CONCLUSIONS

Our method for measuring 2-5AS mRNA concentrations could provide an important marker for selecting patients for IFN therapy and may be useful for the development of more effective therapeutic strategies for chronic hepatitis C.

Expression of interferon-alpha subtypes in peripheral mononuclear cells from patients with chronic hepatitis C: a role for interferon-alpha5

Interferon (IFN)-alpha is a family of antiviral proteins encoded by different genes. The biological significance of the existence of various IFN-alpha subtypes is not clear. We have investigated the interferon system in chronic hepatitis C virus (HCV) infection, a disease that responds to interferon-alpha2 therapy in only a limited proportion of cases. We analysed the expression of interferon regulatory factor (IRF)-1, IRF-2, and IFN-alpha subtypes in nonstimulated and Sendai virus-stimulated peripheral blood mononuclear cells (PBMC) from HCV infected patients and healthy controls. We observed that the IRF-1 mRNA and IRF-1/IRF-2 ratios were increased in PBMC from hepatitis C patients with respect to normal subjects. Sendai virus stimulation of PBMC led to a significant increase in the levels of IRF-1, IRF-2 and IFN-alpha mRNAs and in the production of IFN-alpha protein with respect to basal values in healthy controls as well as in patients with HCV infection. In addition, we found that while natural HCV infection induced increased IFN-alpha5 expression in PBMC, in vitro infection of these cells with Sendai virus caused a raise in the expression of IFN-alpha8 in both patients and normal controls. In summary, our results indicate that virus-induced activation of the IFN system in human PBMC is associated with selective expression of individual IFN-alpha subtypes, IFN-alpha5 being the specific subtype induced in PBMC from patients with chronic HCV infection.

Hepatitis C virus and interferon resistance

Interferon plays a critical role in the host's natural defense against viral infections and in their treatment. It is the only therapy for hepatitis C virus (HCV) infection; however, many virus isolates are resistant. Several HCV proteins have been shown to possess properties that enable the virus to evade the interferon-mediated cellular antiviral responses.

Interferon alfa-2b alone or in combination with ketoprofen as treatment for interferon-naive chronic hepatitis C patients

BACKGROUND

Non-steroidal anti-inflammatory drugs may amplify the anti-viral effect of alpha-interferon in vitro but in vivo data are still controversial.

AIM

: To test the hypothesis that ketoprofen may increase the rate of response to alpha-interferon of chronic hepatitis C patients.

METHODS

Fifty patients with chronic hepatitis C who had never received alpha-interferon were randomly assigned to receive 3-8 MU of alpha2b-interferon, three times weekly for 6 months, alone or in association with ketoprofen at a dose of 200 mg/day five times weekly. The virological response to treatment (undetectable HCV RNA in serum) was evaluated after 3 months and at the end of treatment, and 6 and 12 months after therapy withdrawal.

RESULTS

One patient under combination therapy stopped the ketoprofen for persisting epigastric pain. Complete response under treatment was observed in 15 out of 24 (62.5%) patients receiving alpha2b-interferon alone and in 14 out of 26 (53.8%) patients under combination therapy (P=N.S.). One year after the end of treatment, a sustained response was seen in 4 out of 24 (16.2%) patients treated with alpha2b-interferon and in 5 out of 26 (19.2%) patients having received the combination (P=N.S.).

CONCLUSION

Administration of ketoprofen does not increase either the primary or the sustained response to alpha2b-interferon therapy of interferon-naive chronic hepatitis C patients.

A bioassay for serum interferon based on induction of 2'5'-oligoadenylate synthetase activity

We have developed a bioassay for interferons (IFN) based on measuring the amounts of 2',5' oligoadenylate synthetase (2-5AS) induced in cells of the THP-1 monocyte line in response to IFN. The assay can be completed in 20 h, gives reproducible results, and is at least 50 times more sensitive to IFN-alpha than conventional cytopathic effect inhibition antiviral assays. It is, respectively, less and much less sensitive to IFN-beta and IFN-gamma. The presence of preexisting 2-5AS activity in a sample does not influence the results. We have used this assay to measure very low levels (0.1-0.5 IU/ml) of endogenously formed IFN-alpha in serum samples from patients with various diseases and also to measure the residual small amounts of IFN-alpha still present in the serum as late as 48 h after an i.m. injection of 3 million IU, which is appreciably later than in previous methods. Thus, our highly sensitive assay offers considerable advantages, not least in relation to the clinical use of IFN.

Interferon resistance of hepatitis C virus genotype 1b: relationship to nonstructural 5A gene quasispecies mutations

A 40-amino-acid sequence located in the nonstructural 5A (NS5A) protein of hepatitis C virus genotype 1b (HCV-1b) was recently suggested to be the interferon sensitivity-determining region (ISDR), because HCV-1b strains with an ISDR amino acid sequence identical to that of the prototype strain HCV-J were found to be resistant to alpha interferon (IFN-alpha) whereas strains with amino acid substitutions were found to be sensitive (N. Enomoto, I. Sakuma, Y. Asahina, M. Kurosaki, T. Murakami, C. Yamamoto, N. Izumi, F. Marumo, and C. Sato, J. Clin. Invest. 96:224-230, 1995; N. Enomoto, I. Sakuma, Y. Asahina, M. Kurosaki, T. Murakami, C. Yamamoto, Y. Ogura, N. Izumi, F. Marumo, and C. Sato, N. Engl. J. Med. 334:77-81, 1996). We used single-strand conformation polymorphism (SSCP) analysis, combined with cloning and sequencing strategies, to characterize NS5A quasispecies in HCV-1b-infected patients and determine the relationships between pre- and posttreatment NS5A quasispecies mutations and the IFN-alpha sensitivity of HCV-1b. The serine residues involved in phosphorylation of NS5A protein were highly conserved both in the various patients and in quasispecies in a given patient, suggesting that phosphorylation is important in NS5A protein function. A hot spot for amino acid substitutions was found at positions 2217 to 2218; it could be the result of either strong selection pressure or tolerance to these amino acid replacements. The proportion of synonymous mutations was significantly higher than the proportion of nonsynonymous mutations, suggesting that genetic variability in the region studied was the result of high mutation rates and viral replication kinetics rather than of positive selection. Sustained HCV RNA clearance was associated with low viral load and low nucleotide sequence entropy, suggesting (i) that the replication kinetics when treatment is started plays a critical role in HCV-1b sensitivity to IFN-alpha and (ii) that HCV-1b resistance to IFN-alpha could be conferred by numerous and/or related mutations that could be patient specific and located at different positions throughout the viral genome and could allow escape variants to be selected by IFN-alpha-stimulated immune responses. No NS5A sequence appeared to be intrinsically resistant or sensitive to IFN-alpha, but the HCV-J sequence was significantly more frequent in nonresponder quasispecies than in sustained virological responder quasispecies, suggesting that the balance between NS5A quasispecies sequences in infected patients could have a subtle regulatory influence on HCV replication.

Tenoxicam, a non-steroid anti-inflammatory drug, is unable to increase the response rate in patients with chronic hepatitis C treated by alpha interferon

The purpose of this study is to compare a combination of interferon (IFN)-alpha2a (Roferon) + Tenoxicam with IFN-alpha2a alone in the treatment of chronic hepatitis C. This prospective, randomized double-blind study included 149 patients, all of whom were diagnosed with active chronic hepatitis C but non-cirrhotic (ALT > or = 1.5 upper limit of normal, anti-hepatitis C virus (HCV) positive by enzyme-linked immunosorbant assay2 and RIBA3). The patients were randomized in two groups, as follows: G1 (n = 76): IFNalpha2a 3 million units times per week during 6 months + placebo; and G2 (n = 73): IFNalpha2a 3 million units three times per week + Tenoxicam (20 mg/day) during 6 months. Alanine aminotransferase (ALT) and HCV RNA were determined before and at months 6 and 12 of treatment. 2'5' oligoadenylate synthetase activity (2'5' AS) was dosed in mononuclear cells before and at 3-month treatment intervals in 28 patients. Liver biopsy was performed before and 6 months after the end of therapy. Parameters were similar before therapy for both groups. Biochemical and virological responses were similar for both groups at month 6 (49.3% vs. 42.9% and 43.3% vs. 38.3%, respectively) and month 12 (28.3% vs. 23.8% and 17.2% vs. 17.5%, respectively). HCV RNA level significantly decreased in both groups at month 6, with no difference whatever the therapy; however, the HCV RNA level returned to initial values at month 12 and was the only significant prognostic factor of a sustained response. No peak of 2'5' AS activity was observed during treatment in patients with dual therapy. A histological improvement was also noted in both groups without difference, regardless of therapy. The percentage of adverse events was identical for both groups. Paracetamol intake, assessed in 80 patients, was 49.1 g per 6 months in the G1 group and 22.5 g per 6 months in the G2 group (not significant). In conclusion, the non-steroid anti-inflammatory drug, Tenoxicam, does not increase IFNalpha efficacy in the treatment of chronic hepatitis C. This combination is well tolerated and partially lowers Paracetamol intake, but not preexisting alpha-IFN adverse events.

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.

Effect of alpha interferon (IFN-alpha) on 2'-5' oligoadenylate synthetase activity in peripheral blood mononuclear cells of patients with chronic hepatitis C: relationship to the antiviral effect of IFN-alpha

Alpha interferon (IFN-alpha) is, to date, the only treatment with proven efficacy in patients with chronic hepatitis C. However, less than 15% of the patients have a sustained response to IFN-alpha. Interferon acts through the induction of various cellular enzymes. Among them, the 2'-5' oligoadenylate synthetase (2-5OAS) is (at least in part) responsible for a direct antiviral effect of IFN-alpha. The aim of this study was to determine whether basal and IFN-alpha-induced in vivo and in vitro 2-5OAS activities measured in peripheral blood mononuclear cells predict biochemical and virological responses to IFN-alpha in patients with chronic hepatitis C. 2-5OAS activity in peripheral blood mononuclear cells and the antiviral effect of IFN-alpha were studied in 36 patients with chronic hepatitis C (27 men and 9 women; mean age, 44.7 years). Basal in vivo 2-5OAS activity (mean +/- standard error of the mean) was 4.41 +/- 0.69 nmol/10(6) cells. It was significantly induced at month 3 of IFN-alpha therapy (18.07 +/- 2.74 nmol/10(6) cells; P = 0.0001). No significant differences were found in basal in vivo 2-5OAS activities, in IFN-alpha-induced/basal in vitro 2-5OAS activity ratios, in IFN-alpha-induced in vivo 2-5OAS activities, and in IFN-alpha-induced/basal in vivo 2-5OAS activity ratios between the patients with and without a biochemical response (normal alanine aminotransferase activity in serum) or a virological response (normal alanine aminotransferase activity in serum and negative hepatitis C virus RNA detection) at any step of the study. At month 3 of therapy, p69, which is considered to be the active isoform of 2-5OAS, was induced, as demonstrated by Western blot (immunoblot) analysis in 50% of the patients, and induction of the p100 isoform was observed in 70% of the patients. No significant relationship with the response to IFN-alpha therapy was observed. Our results suggest that a deficiency of the IFN-alpha-dependent 2-5OAS system, which could be genetically determined, is unlikely to be responsible for the failure to achieve biochemical and virological responses to IFN-alpha therapy in patients with chronic hepatitis C.