HBcrAg values may predict virological and immunological responses to pegIFN-α in NUC-suppressed HBeAg-negative chronic hepatitis B.

Objective: Selected populations of patients with chronic hepatitis B (CHB) may benefit from a combined use of pegylated interferon-alpha (pegIFN-α) and nucleos(t)ides (NUCs). The aim of our study was to assess the immunomodulatory effect of pegIFN-α on T and natural killer (NK) cell responses in NUC-suppressed patients to identify cellular and/or serological parameters to predict better T cell-restoring effect and better control of infection in response to pegIFN-α for a tailored application of IFN-α add-on.

Design: 53 HBeAg-negative NUC-treated patients with CHB were randomised at a 1:1 ratio to receive pegIFN-α-2a for 48 weeks, or to continue NUC therapy and then followed up for at least 6 months maintaining NUCs.

What Is the Current Status of Hepatitis B Virus Viro-Immunology?

The natural history of hepatitis B virus (HBV) infection is closely dependent on the dynamic interplay between the host immune response and viral replication. Spontaneous HBV clearance in acute self-limited infection is the result of an adequate and efficient antiviral immune response. Instead, it is widely recognized that in chronic HBV infection, immunologic dysfunction contributes to viral persistence.

FluoroSpot assay to analyze SARS-CoV-2-specific T cell responses.

Monitoring antigen-specific T cell frequency and function is essential to assess the host immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Here, we present a FluoroSpot assay for concurrently detecting ex vivo antiviral cytokine production by SARS-CoV-2-specific T cells following peptide stimulation. We then detail intracellular cytokine staining by flow cytometry to further validate the FluoroSpot assay results and define the specific T cell subpopulations.

Deregulated intracellular pathways define novel molecular targets for HBV-specific CD8 T cell reconstitution in chronic hepatitis B.

Background & Aims: In chronic HBV infection, elevated reactive oxygen species levels derived from dysfunctional mitochondria can cause increased protein oxidation and DNA damage in exhausted virus-specific CD8 T cells. The aim of this study was to understand how these defects are mechanistically interconnected to further elucidate T cell exhaustion pathogenesis and, doing so, to devise novel T cell-based therapies.

Methods: DNA damage and repair mechanisms, including parylation, CD38 expression, and telomere length were studied in HBV-specific CD8 T cells from chronic HBV patients.

Phenotypic CD8 T cell profiling in chronic hepatitis B to predict HBV-specific CD8 T cell susceptibility to functional restoration in vitro.

Objective: Exhausted hepatitis B virus (HBV)-specific CD8 T cells in chronic HBV infection are broadly heterogeneous. Characterisation of their functional impairment may allow to distinguish patients with different capacity to control infection and reconstitute antiviral function.

Design: HBV dextramer+CD8 T cells were analysed ex vivo for coexpression of checkpoint/differentiation markers, transcription factors and cytokines in 35 patients with HLA-A2+chronic hepatitis B (CHB) and in 29 control HBsAg negative CHB patients who seroconverted after NUC treatment or spontaneously.

Antigen Load and T Cell Function: A Challenging Interaction in HBV Infection.

Current treatment for chronic HBV infection is mainly based on nucleos(t)ide analogues, that in most cases need to be administered for a patient's lifetime. There is therefore a pressing need to develop new therapeutic strategies to shorten antiviral treatments. A severe dysfunction of virus-specific T cell responses contributes to virus persistence; hence, immune-modulation to reconstitute an efficient host antiviral response is considered a potential approach for HBV cure.

Unraveling the Multifaceted Nature of CD8 T Cell Exhaustion Provides the Molecular Basis for Therapeutic T Cell Reconstitution in Chronic Hepatitis B and C.

In chronic hepatitis B and C virus infections persistently elevated antigen levels drive CD8+ T cells toward a peculiar differentiation state known as T cell exhaustion, which poses crucial constraints to antiviral immunity. Available evidence indicates that T cell exhaustion is associated with a series of metabolic and signaling deregulations and with a very peculiar epigenetic status which all together lead to reduced effector functions. A clear mechanistic network explaining how intracellular metabolic derangements, transcriptional and signaling alterations so far described are interconnected in a comprehensive and unified view of the T cell exhaustion differentiation profile is still lacking.

Metabolic regulation of the HBV-specific T cell function.

Chronically HBV infected subjects are more than 260 million worldwide; cirrhosis and liver cancer represent possible outcomes which affect around 700,000 patients per year. Both innate and adaptive immune responses are necessary for viral control and both have been shown to be defective in chronic patients. Metabolic remodeling is an essential process in T cell biology, particularly for T cell activation, differentiation and survival.

Functional reconstitution of HBV-specific CD8 T cells by in vitro polyphenol treatment in chronic hepatitis B.

Background & Aims: In chronic HBV infection, mitochondrial functions and proteostasis are dysregulated in exhausted HBV-specific CD8 T cells. To better characterise the potential involvement of deregulated protein degradation mechanisms in T cell exhaustion, we analysed lysosome-mediated autophagy in HBV-specific CD8 T cells. Bioactive compounds able to simultaneously target both mitochondrial functions and proteostasis were tested to identify optimal combination strategies to reconstitute efficient antiviral CD8 T cell responses in patients with chronic HBV infection.

Targeting p53 and histone methyltransferases restores exhausted CD8+ T cells in HCV infection.

Hepatitis C virus infection (HCV) represents a unique model to characterize, from early to late stages of infection, the T cell differentiation process leading to exhaustion of human CD8+ T cells. Here we show that in early HCV infection, exhaustion-committed virus-specific CD8+ T cells display a marked upregulation of transcription associated with impaired glycolytic and mitochondrial functions, that are linked to enhanced ataxia-telangiectasia mutated (ATM) and p53 signaling. After evolution to chronic infection, exhaustion of HCV-specific T cell responses is instead characterized by a broad gene downregulation associated with a wide metabolic and anti-viral function impairment, which can be rescued by histone methyltransferase inhibitors.

The Good and the Bad of Natural Killer Cells in Virus Control: Perspective for Anti-HBV Therapy.

Immune modulatory therapies are widely believed to represent potential therapeutic strategies for chronic hepatitis B infection (CHB). Among the cellular targets for immune interventions, Natural Killer (NK) cells represent possible candidates because they have a key role in anti-viral control by producing cytokines and by exerting cytotoxic functions against virus-infected cells. However, in patients with chronic hepatitis B, NK cells have been described to be more pathogenic than protective with preserved cytolytic activity but with a poor capacity to produce anti-viral cytokines.

HBV Immune-Therapy: From Molecular Mechanisms to Clinical Applications.

Chronic hepatitis B virus (HBV) infection represents a worldwide public health concern with approximately 250 million people chronically infected and at risk of developing liver cirrhosis and hepatocellular carcinoma. Nucleos(t)ide analogues (NUC) are the most widely used therapies for HBV infection, but they often require long-lasting administration to avoid the risk of HBV reactivation at withdrawal. Therefore, there is an urgent need to develop novel treatments to shorten the duration of NUC therapy by accelerating virus control, and to complement the effect of available anti-viral therapies.

Lack of full CD8 functional restoration after antiviral treatment for acute and chronic hepatitis C virus infection.

Background: Hepatitis C virus (HCV) persistence is associated with impaired CD8 functions. Whether functional restoration of CD8 T cells chronically exposed to antigen can be obtained once the antigen is removed remains to be clarified.

Objective: To determine whether clearance of HCV by antiviral treatment can fully restore the antiviral function of HCV-specific CD8 cells.

Peginterferon-α does not improve early peripheral blood HBV-specific T-cell responses in HBeAg-negative chronic hepatitis.

Background & Aims: The effect of IFN-α therapy on HBV-specific T-cell responses in HBeAg-negative, genotype D, chronic hepatitis B is largely undefined. Understanding to what extent IFN-α can modulate HBV-specific T-cells is important to define strategies to optimize IFN efficacy and to identify immunological parameters to predict response to therapy.

Methods: HBV-specific T-cell responses were analyzed longitudinally ex vivo and after expansion in vitro in 15 patients with genotype D, HBeAg-negative chronic hepatitis B treated with peginterferon-α-2a.

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).

HCV-specific T-cell response in relation to viral kinetics and treatment outcome (DITTO-HCV project).

Background & Aims: The second slope of viral decline induced by interferon treatment has been suggested to be influenced mainly by the hepatitis C virus (HCV)-specific T-cell response; however, this hypothesis needs to be validated by results derived from experimental studies.

Methods: To address this issue, the HCV-specific T-cell response of 32 genotype-1-infected patients of the 270 patients enrolled in the dynamically individualized treatment of hepatitis C infection and correlates of viral/host dynamics phase III, open-label, randomized, multicenter trial was studied in relation to viral kinetics and treatment outcome.

Results: Greater proliferative responses by HCV-specific CD8 cells were found before treatment in patients with a fast viral decline and with a sustained viral response.

Dysfunction and functional restoration of HCV-specific CD8 responses in chronic hepatitis C virus infection.

Unlabelled: The functional impairment of HCV-specific T cell responses is believed to be an important determinant of HCV persistence, but the functional T cell defects of patients with chronic hepatitis C (CH-C) are only partially defined. CD8 responses to HLA-A2-restricted epitopes of HCV and other unrelated viruses were studied in 23 HLA-A2-positive patients both ex vivo and after in vitro culture. Degranulation capacity, intracellular perforin, and granzyme-A content and cytokine production (IFN-gamma, TNF-alpha) by HCV- and non-HCV-specific CD8 cells were tested both ex vivo and in vitro, whereas cytolytic activity was studied after 10 days' expansion in vitro.

Radiofrequency thermal ablation of hepatocellular carcinoma liver nodules can activate and enhance tumor-specific T-cell responses.

Radiofrequency thermal ablation (RFA) destroys tumoral tissue generating a local necrosis followed by marked inflammatory response with a dense T-cell infiltrate. In this study, we tested whether hepatocellular carcinoma thermal ablation can induce or enhance T-cell responses specific for hepatocellular carcinoma-associated antigens. Peripheral blood mononuclear cells derived from 20 patients with hepatocellular carcinoma were stimulated before and a month after RFA treatment with autologous hepatocellular carcinoma-derived protein lysates obtained before and immediately after RFA treatment.

Parenteral exposure to high HIV viremia leads to virus-specific T cell priming without evidence of infection.

Previous studies on CTL responses in HIV-exposed uninfected individuals assumed that the patients were exposed to replicating HIV, but the possibility that the immune responses detected were primed by exposure to a defective virus or viral antigen could not be excluded. Epidemiological and laboratory analysis of a nosocomial outbreak of acute hepatitis B unequivocally allowed the identification of an HIV-1- and HBV-co-infected patient with high plasma levels of both viruses, as the source case of the epidemics. This clinical setting provided a natural model for testing the HIV-specific T cell response in patients exposed to blood from a patient with highly replicating HIV.

Transient restoration of anti-viral T cell responses induced by lamivudine therapy in chronic hepatitis B.

Background/aims: Lamivudine therapy in patients with chronic hepatitis B can induce the recovery of antiviral T cell responses. It is unknown whether the recovery of T cell responsiveness is long-lasting and persists throughout the treatment and whether the elevation of viremia which follows therapy withdrawal can restore a condition of T cell unresponsiveness.

Methods: Frequency and function of circulating hepatitis B virus (HBV)-specific CD4 and CD8 cells from 12 hepatitis e surface antigen + patients with chronic hepatitis B were studied longitudinally before, during and after lamivudine therapy by intracellular cytokine staining, proliferation and cytotoxicity assays against HBV proteins and peptides.

Oral lichen planus pathogenesis: A role for the HCV-specific cellular immune response.

Hepatitis C virus infection can be associated with different extrahepatic manifestations, including lichen planus; however, no clear role for HCV in their pathogenesis has been established. T cells were isolated from lichen biopsy specimens of 7 HCV positive patients with oral lichen planus. HCV-specific CD4(+) T-cell lines were obtained in 4 patients from lichen lesions but only in 2 of them from the peripheral blood.

Intrahepatic and circulating HLA class II-restricted, hepatitis C virus-specific T cells: functional characterization in patients with chronic hepatitis C.

To compare the functional features of circulating and intrahepatic hepatitis C virus (HCV)-specific CD4+ T cells in chronic HCV infection, peripheral blood and liver-infiltrating lymphocytes from 29 patients with chronic hepatitis C were stimulated with structural and nonstructural HCV proteins to produce antigen-specific T-cell lines and clones. Antigen specificity, fine specificity, phenotype, cytokine production, and T-cell receptor (TCR)-vbeta chain expression were analyzed. The results indicate a hierarchy of stimulatory capacity by the different HCV proteins, core being the antigen most frequently recognized by CD4+ intrahepatic lymphocytes, followed by NS4 and NS5.