The quantitative humoral immune response to the hepatitis C virus is correlated with disease activity and response to interferon-alpha

Relationship between humoral response against hepatitis C virus and disease overcome

Abstract

Hepatitis C virus infection leads to liver disease whose severity can range from mild to serious lifelong illness. However the parameters involved in the evolution of the disease are still unknown. Among other factors, the virus-elicited antibody profile is suspected to play a role in the outcome of the disease. Analysis of the relationship between anti-virus antibodies and disease state requires the analysis of a large number of serums from patients (hepatitis C virus+) and of epitopes from the viral proteins. Such a study would benefit from microarray-based screening systems that are appropriate for high-throughput assays.

We used a method combining peptide chips and surface plasmon resonance imaging previously shown to be suitable for analyzing complex mediums and detecting peptide-protein interactions. 56 peptides covering the entire viral proteome were grafted on chips and their interaction with antibodies present in the 68 injected serums from infected and non-infected donors was measured. Statistical analyses were conducted to determine a possible relationship between antibodies (specificity and amount) and disease states.

A good discrimination between infected and non-infected donors validated our approach, and several correlations between antibodies profiles and clinical parameters have been identified. In particular, we demonstrated that ratios between particular antibodies levels allow for accurate discrimination of patients according to their pathologic states.

Conclusion

Humoral response against hepatitis C virus linear epitopes is partly modified according to the disease state. This study highlights the importance of considering relative quantities of antibodies with different specificities rather than the amount of each antibody.

Electronic supplementary material

The online version of this article (doi: 10.1186/2193-1801-3-56) contains supplementary material, which is available to authorized users.

HLA-A2-restricted cytotoxic T lymphocyte activity during interferon beta therapy in patients with chronic hepatitis C

BACKGROUND AND AIMS

Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTL) may contribute to viral clearance and liver cell injury in patients with chronic hepatitis C. In the present study, we attempted to determine the serial HCV-specific CTL activity during interferon-beta (IFN-beta) therapy in patients with chronic hepatitis C and whether there is any relationship between the CTL response and clinical response to IFN-beta therapy.

METHODS

Eight HLA-A2-positive patients with chronic hepatitis C were treated initially with 6 million U/ml of IFN-beta every day for 8 weeks and then 3 times weekly for the subsequent 16 weeks. Peripheral blood mononuclear cells (PBMC) were collected before the start, 4 weeks after the start, and after the end of IFN treatment and were stimulated with 2 peptides corresponding to core sequences, which were previously reported to have an HLA-A2 restricted-CTL epitopes. Cytolytic activity was determined by a standard 51Cr-release assay using allogenic HLA-matched EBV-transformed B lymphoblastoid cell lines (B-LCL).

RESULTS

HCV-specific CTL responses were detected in 2 of the 8 patients before treatment with IFN-beta. One of 2 patients was not observed HCV-specific CTL responses after 4 weeks of IFN-beta treatment, however these two patients showed CTL responses at the end of IFN-beta treatment, and finally HCV-RNA was negative. In addition, HCV-specific CTL responses were observed in 4 patients after 4 weeks of IFN-beta treatment. Three of these 4 patients showed CTL responses only at 4 weeks after IFN-beta treatment. However, there were no differences between clinical parameters or between IFN efficacy in HCV specific CTL response-positive (n = 4) and -negative (n = 4) patients at 4 weeks after the start of IFN-beta treatment.

CONCLUSIONS

These findings suggest that there are few relations between peripheral HCV-specific CTL response and clinical response to IFN therapy in patients with chronic hepatitis C, although IFN enhances the host immune response against HCV synergistically with antiviral activities.

Quantitative analysis of specific Th1/Th2 helper cell responses and IgG subtype antibodies in interferon-alpha-treated patients with chronic hepatitis C

This study aimed to characterise the immune mechanisms relevant to viral clearance in interferon (IFN)-alpha-treated chronic hepatitis C virus (HCV) infection. Proliferative responses of peripheral blood mononuclear cells from sustained complete IFN-alpha therapy responders (n = 8), nonresponders (n = 13), untreated patients (n = 10), and healthy controls (n = 5) were measured retrospectively upon stimulation with recombinant HCV-antigens (core, helicase, NS3, NS4, and NS5) and the secretion of IFN-gamma and interleukins (IL-4, IL-5, IL-10, and IL-12) were tested by ELISA. Furthermore, IFN-gamma as well as IL-10 secreting CD4+ T cells were quantitated by intracellular cytokine staining. Anti-HCV core and NS3-specific IgG subclass antibodies were quantitated in the corresponding patient sera. Sustained therapy responders had more frequent and stronger NS3 and helicase-specific cellular immune responses than nonresponders, untreated HCV patients and healthy controls. Independent from therapy outcome HCV-stimulated T cells in IFN-alpha treated patients secreted preferentially IFN-gamma The Th2 cytokines IL-4 and IL-10 were even decreased in nonresponders, while the IL-12 secretion was not influenced. With respect to the humoral immune response sustained complete responders showed significantly reduced IFN-gamma independent anti-HCV-core and -NS3 IgG1 antibody synthesis. In conclusion, vigorous NS3-specific T-helper cell responses were associated with viral clearance in IFN-alpha recipients; however, the cytokine and antibody analysis argues against a Th1/Th2 imbalance as a major factor that influence the therapy outcome.

Modulation of tumor necrosis factor receptors 1 and 2 in chronic hepatitis B and C: the differences and implications in pathogenesis

Tumor necrosis factor (TNF) plays a role in the pathogenesis of chronic hepatitis B (CHB) and chronic hepatitis C (CHC). The difference in the cytokine responses between hepatitis B virus (HBV) and hepatitis C virus (HCV) infections may have implications in the pathogenesis of these diseases. We performed a comparative study to examine the possible differences in the TNF-TNF receptor (TNFR) response between CHB and CHC. We studied the cytokine levels of 38 patients with CHB, 40 patients with CHC and 9 patients with dual hepatitis B and C, and compared them with the baseline levels of 12 healthy controls. The plasma levels of TNF-alpha, interferon-gamma, interleukin (IL)-2, IL-4, IL-10 and soluble TNFR-1 and 2 (sTNFR-1 and 2) were quantified by enzyme-linked immunosorbent assays. The expression of TNFR-1 and 2 in liver tissues was examined in 30 cases of CHB and 15 cases of CHC by semiquantitative reverse transcription polymerase chain reaction. The results showed that sTNFR-1 levels correlated with liver inflammation in all patients, whereas this correlation was not found with sTNFR-2 or other cytokines. Liver inflammation indicators were higher in HCV RNA+ than in HCV RNA- CHC. Most significantly, sTNFR-1 levels correlated with liver inflammation in CHB, but not in CHC. However, the expression of TNFR-1 and 2 in liver was similar between CHB and CHC. These findings suggest that the TNFR signal transduction pathway is modulated differently in HBV and HCV infection.

Applications of flow cytometry to clinical microbiology

Classical microbiology techniques are relatively slow in comparison to other analytical techniques, in many cases due to the need to culture the microorganisms. Furthermore, classical approaches are difficult with unculturable microorganisms. More recently, the emergence of molecular biology techniques, particularly those on antibodies and nucleic acid probes combined with amplification techniques, has provided speediness and specificity to microbiological diagnosis. Flow cytometry (FCM) allows single- or multiple-microbe detection in clinical samples in an easy, reliable, and fast way. Microbes can be identified on the basis of their peculiar cytometric parameters or by means of certain fluorochromes that can be used either independently or bound to specific antibodies or oligonucleotides. FCM has permitted the development of quantitative procedures to assess antimicrobial susceptibility and drug cytotoxicity in a rapid, accurate, and highly reproducible way. Furthermore, this technique allows the monitoring of in vitro antimicrobial activity and of antimicrobial treatments ex vivo. The most outstanding contribution of FCM is the possibility of detecting the presence of heterogeneous populations with different responses to antimicrobial treatments. Despite these advantages, the application of FCM in clinical microbiology is not yet widespread, probably due to the lack of access to flow cytometers or the lack of knowledge about the potential of this technique. One of the goals of this review is to attempt to mitigate this latter circumstance. We are convinced that in the near future, the availability of commercial kits should increase the use of this technique in the clinical microbiology laboratory.

Applications of flow cytometry to clinical microbiology

Classical microbiology techniques are relatively slow in comparison to other analytical techniques, in many cases due to the need to culture the microorganisms. Furthermore, classical approaches are difficult with unculturable microorganisms. More recently, the emergence of molecular biology techniques, particularly those on antibodies and nucleic acid probes combined with amplification techniques, has provided speediness and specificity to microbiological diagnosis. Flow cytometry (FCM) allows single- or multiple-microbe detection in clinical samples in an easy, reliable, and fast way. Microbes can be identified on the basis of their peculiar cytometric parameters or by means of certain fluorochromes that can be used either independently or bound to specific antibodies or oligonucleotides. FCM has permitted the development of quantitative procedures to assess antimicrobial susceptibility and drug cytotoxicity in a rapid, accurate, and highly reproducible way. Furthermore, this technique allows the monitoring of in vitro antimicrobial activity and of antimicrobial treatments ex vivo. The most outstanding contribution of FCM is the possibility of detecting the presence of heterogeneous populations with different responses to antimicrobial treatments. Despite these advantages, the application of FCM in clinical microbiology is not yet widespread, probably due to the lack of access to flow cytometers or the lack of knowledge about the potential of this technique. One of the goals of this review is to attempt to mitigate this latter circumstance. We are convinced that in the near future, the availability of commercial kits should increase the use of this technique in the clinical microbiology laboratory.

Diagnostic value of anti-hepatitis C virus (HCV) core immunoglobulin M in recurrence of HCV infection after orthotopic liver transplantation

The significance of anti-hepatitis C virus (HCV) core immunoglobulin M (IgM) and its relationship with genotypes, alanine aminotransferase abnormality, and histological data were studied for 18 patients who had undergone orthotopic liver transplantation due to HCV-related end-stage disease. During follow-up, IgM response seemed to be associated with the recurrence of HCV infection but did not correlate with abnormal alanine aminotransferase levels and histological data. In addition, the results of this study indicated that the detection of HCV RNA is critical for diagnosis of reinfection in liver transplantation.

Viral and host factors in the prediction of response to interferon-alpha therapy in chronic hepatitis C after long-term follow-up

Acute infection with hepatitis C virus (HCV) develops into a chronic hepatitis in about 50-70% of patients. Treatment of these patients with interferon-alpha (IFN-alpha) results in a sustained long-term response in only 15-20% but causes numerous unwanted side-effects in a higher percentage of patients. The aim of our study was to define host or viral parameters that would allow identification of responders and non-responders to IFN-alpha prior to the onset of treatment. We studied a group of 87 patients suffering from chronic hepatitis C who were treated with IFN-alpha. After long-term follow-up, 18 patients (21%) showed a sustained response to IFN-alpha therapy (normalization of serum transaminases and loss of viral RNA from serum) for up to 7 years after therapy had ceased. By univariate and multivariate analyses, no host factors were found to be predictive of response to therapy. Neither the degree of inflammation or fibrosis in liver biopsy samples obtained before treatment nor immunogenetic factors (major histocompatibility complex II haplotype and tumour necrosis factor-alpha promoter polymorphism) were associated with response to therapy. In contrast, viral parameters showed a strong association with response to therapy. HCV genotype 3 was found significantly more frequently in responders (P = 0.034), and mean HCV RNA concentration was lower in responders (3.1 x 10(4)) than in non-responders (2.5 x 10(5)) (P = 0.01). By multivariate analysis, both HCV genotype and HCV RNA concentration were independent predictors of response to therapy. However, exact prediction of response to treatment for an individual patient was not possible on the basis of pretreatment viral RNA concentration or viral genotype. The best association with response to therapy was found to be clearance of HCV RNA from serum 3 months after the start of treatment (32 of 34 partial and sustained responders vs 0 of 53 non-responders; P = 0.001). In conclusion, determination of pretreatment viral factors, but not host factors, was significantly correlated with treatment response but did not give an accurate prediction for patients, whereas clearance of HCV RNA from serum after 3 months of therapy was predictive of response to therapy.

The cellular immune responses induced in the follow-up of interferon-alpha treated patients with chronic hepatitis C may determine the therapy outcome

BACKGROUND/AIMS

To study whether the host's immune response determines viral clearance in chronic hepatitis C, virological markers and antigen-specific T cell reactions were analysed in 30 chronic HCV carriers followed up during interferon-alpha therapy, 11 untreated anti-HCV positive individuals and 10 healthy controls.

METHODS

Proliferative T helper cell responses to recombinant HCV core and non-structural antigens were monitored by 3H-thymidine uptake assay and compared to quantitative viraemia levels and HCV genotypes.

RESULTS

Of the 30 treated patients, six had sustained complete responses (20%), another six were transient therapy responders (20%) and 18 were non-responders (60%). Viral clearance was associated with the HCV genotype 3 and low pretreatment viral load. In a substantial proportion of complete and transient therapy responders, increased NS3-, helicase- and NS4-antigen-specific T cell responses were observed during interferon-alpha therapy. In non-responders and in the later clinical courses of transient therapy responders, core and NS5-specific T cell responses dominated. In addition, 11 untreated anti-HCV antibody positive individuals were studied. Two HCV-RNA negative patients who might have recovered from HCV infection showed strong persistent lymphoproliferative responses to NS3, helicase and NS4 antigens, whereas seven of the nine viraemic patients reacted with HCV core or NS5 antigens.

CONCLUSIONS

Interferon-alpha treatment enhances NS3-, helicase- and NS4-antigen-specific T helper cell responses in patients with viral clearance, whereas viral persistence was associated with increased T cell reactivities against core and NS5 antigens. Immunogenetical, immunological and virological factors that may influence differential T cell induction in chronic hepatitis C are discussed.