Cytotoxic T lymphocytes recognize an HLA-A2-restricted epitope within the hepatitis B virus nucleocapsid antigen

The absence of readily manipulable experimental systems to study the cytotoxic T lymphocyte (CTL) response against hepatitis B virus (HBV) antigens has thus far precluded a definitive demonstration of the role played by this response in the pathogenesis of liver cell injury and viral clearance during HBV infection. To circumvent the problem that HBV infection of human cells in vitro for production of stimulator/target systems for CTL analysis is not feasible, a panel of 22 overlapping synthetic peptides covering the entire amino acid sequence of the HBV core (HBcAg) and e (HBeAg) antigens were used to induce and to analyze the HBV nucleocapsid-specific CTL response in nine patients with acute hepatitis B, six patients with chronic active hepatitis B, and eight normal controls. By using this approach, we have identified an HLA-A2-restricted CTL epitope, located within the NH2-terminal region of the HBV core molecule, which is shared with the e antigen and is readily recognized by peripheral blood mononudear cells from patients with self-limited acute hepatitis B but less efficiently in chronic HBV infection. Our study provides the first direct evidence of HLA class I-restricted T cell cytotoxicity against HBV in humans. Furthermore, the different response in HBV-infected subjects who successfully clear the virus (acute patients) in comparison with patients who do not succeed (chronic patients

What to start with in first line treatment of chronic hepatitis B patients: an Italian multicentre observational cohort, HBV-RER study group

Treatment options for chronic hepatitis B (CHB) are pegylated interferon (Peg-IFN) in minimal-mild liver fibrosis and nucleot(s)ide analogues (NUC) in more advanced disease. Since little is known about their use in daily clinical practice, we conducted a multicentre prospective study to investigate treatment regimens applied to na\uefve CHB patients in real life. HBV-RER is an observational multicentre Italian network that collect clinic and virologic data of patients with CHB. Among the 2527 CHB patients seen during the study period (2009 - 2012), 502 patients started a first line antiviral treatment. Liver biopsy was performed in 30.9% of the patients, with high levels of fibrosis being detected in 19.4% of them. In 216 patients (43%) Peg-IFN was used as first-line therapy while the remaining patients started NUC therapy (entecavir and tenofovir in 75%, lamivudine in 15%, telbivudine and adefovir 10%). By multivariate logistic regression, an age under 40 (OR 0.92, 95%IC 0.90-0.94; p <0.001) and the execution of liver biopsy (OR 3.83; 95%IQR 1.76-8.36; p <0.001) were the only determinants of choice between Peg-IFN vs NUC. Peg-IFN was expected to be used in first-line treatment for CHB in 70% of the patients based on Italian recommendations, but a much lower proportion of patients were actually treated with Peg-IFN with a limited use of the biopsy. Thus, in daily clinical practice physicians prefer to use NUCs, presumably because of their optimal tolerability and anti-viral efficacy, even if they frequently require life-long treatment as opposed to the short duration of Peg-IFN

Combined blockade of programmed death-1 and activation of CD137 increase responses of human liver T cells against HBV, but not HCV

In patients with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, antiviral functions of T cells are impaired; these might be increased by blocking T-cell co-inhibitory pathways, such as preventing interaction between the receptor programmed death (PD)-1 and its ligand, PD-L1. We attempted to optimize the restoration of T-cell functions in patients with chronic HBV or HCV infection with a combination of reagents that block PD-1 interaction with PD-L1 and stimulate T-cell signaling via CD137, a member of the tumor necrosis factor-receptor family

Characterization of Hepatitis B Virus (HBV)-Specific T-Cell Dysfunction in Chronic HBV Infection

Dysfunctional CD8(+) T cells present in chronic virus infections can express programmed death 1 (PD-1) molecules, and the inhibition of the engagement of PD-1 with its ligand (PD-L1) has been reported to enhance the antiviral function of these T cells. We took advantage of the wide fluctuations in levels of viremia which are typical of chronic hepatitis B virus (HBV) infection to comprehensively analyze the impact of prolonged exposure to different virus quantities on virus-specific T-cell dysfunction and on its reversibility through the blocking of the PD-1/PD-L1 pathway. We confirm that chronic HBV infection has a profound effect on the HBV-specific T-cell repertoire. Despite the use of a comprehensive panel of peptides covering all HBV proteins, HBV-specific T cells were rarely observed directly ex vivo in samples from patients with chronic infection, in contrast to those from patients with acute HBV infection. In chronic HBV infection, virus-specific T cells were detected mainly in patients with lower levels of viremia. These HBV-specific CD8(+) T cells expressed PD-1, and their function was improved by the blocking of PD-1/PD-L1 engagement. Thus, a broad spectrum of anti-HBV immunity is expressed by patients with chronic HBV infection and this spectrum is proportional to HBV replication levels and can be improved by blocking the PD-1/PD-L1 pathway. This information may be useful for the design of immunotherapeutic strategies to complement and optimize available antiviral therapies

The Characteristics of the Cell-Mediated Immune Response Identify Different Profiles of Occult Hepatitis B Virus Infection

Background& Aims: Hepatitis B virus (HBV) DNA detection in serum and/or in the liver of hepatitis B surface antigen (HBsAg)-negative patients with or without serologic markers of previous viral exposure is defined as occult HBV infection. Because the role of the adaptive response in keeping HBV replication under control in occult infection still is undefined, this study was performed to characterize the features of the HBV-specific T-cell response in this condition. Methods: HBV-specific T-cell frequency and function were tested ex vivo and after in vitro expansion in 32 HBsAg-negative patients undergoing diagnostic liver biopsy for chronic hepatitis C: 18 with occult HBV infection (11 anti-HBc-negative and 7 anti-HBc-positive patients) defined by the detection of intrahepatic HBV DNA by polymerase chain reaction; 14 without detectable intrahepatic HBV DNA (5 anti-HBc-positive and 9 anti-HBc-negative patients). Six patients with chronic hepatitis B and 7 HBsAg-inactive carriers were studied for comparison. Results: The presence or absence of serologic HBV markers defined 2 profiles of HBV-specific T-cell responses in occult infection. Anti-HBc-positive patients showed a T-cell response typical of protective memory, suggesting that this condition represents a resolved infection with immune-mediated virus control. In contrast, HBV-specific T cells in anti-HBc-negative patients did not readily expand and produce interferon-γ in vitro, suggesting the possibility of a low-dose infection insufficient to allow maturation of protective memory. Conclusions: Our results suggest different mechanisms of control of viral replication in seropositive and seronegative occult infections. Additional studies aimed at understanding possible different clinical implications are needed. © 2008 AGA Institute

Restored function of HBV-specific T cells after long-term effective therapy with nucleos(t)ide analogues

BACKGROUND & AIMS: In patients with chronic hepatitis B virus (HBV) infection, persistent exposure to high concentrations of antigen can disrupt T-cell functions. It is not clear to what extent long-term suppression of HBV by nucleos(t)ide analogues can restore antiviral T-cell functions. We compared HBV-specific T-cell responses of patients treated with nucleos(t)ide analogues with those detected in other conditions of HBV control. METHODS: We analyzed intracellular levels of interferon gamma, interleukin-2, and tumor necrosis factor α in HBV-specific T cells after 10 days of stimulation with peptides covering the overall HBV genotype D sequence and ex vivo with selected CD8 epitopes and the corresponding HLA-A2 dextramers. Findings from patients treated with nucleos(t)ide analogues who had complete (HBV DNA negative/antibody to hepatitis B surface antigen positive) or partial (HBV DNA negative/hepatitis B surface antigen positive) control of their infections were compared with those of patients with spontaneous or interferon alfa-induced resolution of acute or chronic infections, inactive HBV carriers, or untreated hepatitis B e antigen-negative patients with chronic infections. RESULTS: Although HBV-specific T cells from nucleos(t)ide analogue-treated patients with complete control of infection were dysfunctional ex vivo, they had efficient responses after in vitro expansion. These responses were comparable to those of patients who spontaneously resolved acute HBV infection. Nucleos(t)ide analogue-treated patients who were HBV DNA negative but hepatitis B surface antigen positive had lower levels of T-cell responses but responses greater than those of untreated patients with chronic infection. CONCLUSIONS: In vitro reactivity can be restored to T cells from patients with suppressed HBV infection following long-term treatment with nucleos(t)ide analogues, despite prolonged exposure to large loads of antigen. Immune therapies that increase the antiviral T-cell response might increase the likelihood of complete HBV control in patients undergoing long-term nucleos(t)ide analogue treatment. © 2012 AGA Institute

Le manifestazioni extraepatiche del virus dell'epatite C: inquadramento e gestione clinica

Printed from http://www.webaisf.org target=NewWindow>www.webaisf.org (February 2005)Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 , Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal