Impact of HBsAg and HBcrAg levels on phenotype and function of HBV-specific T cells in patients with chronic hepatitis B virus infection

Potential role of Vitamin D in immune response in patients with viral hepatitis

BACKGROUND

To study the relationship of Vitamin D with innate and adaptive immune response parameters in chronic hepatitis B and C patients.

METHODS

The laboratory data between January 1, 2013 and February 1, 2023, for patients with chronic hepatitis B (CHB), and chronic hepatitis C (CHC) were extracted. Serum 25-hydroxyl vitamin D, hepatitis B virus serological markers, complements, and subsets of T lymphocytes were determined. Study cohorts were divided into groups based on serum 25-hydroxyl vitamin D levels with further evaluation of laboratory data.

RESULTS

In CHB and CHC patients the percentage of CD4+ T lymphocytes and the CD4+/CD8+ ratio significantly decreased (P < 0.05), but the percentage of CD8+ increased (P < 0.05) compared to the control group. In CHB patients Vitamin D decrease was significant (P < 0.001) but not in CHC patients. Vitamin D showed a moderate negative influence on the CD8 cell count in CHB patients. The positive ratio of HBV DNA and HBsAg decreased with increasing serum vitamin D levels. The vitamin D deficient group showed significantly lower antibody production compared to the normal group, and exhibited significantly decreased CD4 numbers and increased CD8 numbers (P < 0.05 and P < 0.001, respectively), while the CD4/CD8 ratio was also significantly decreased in the insufficiency group (P < 0.001). Complement C3 levels were not associated with CD4 and CD8, but had an inverse relation with Vitamin D. Vitamin D levels were significantly associated with complement C3, CD8+, CD4+, CD19+ cells, and HBV DNA levels.

CONCLUSIONS

Vitamin D may be a modulator of immune function not only via CD8+ and CD4+ cells but also via CD19+ cells in the course of chronic HBV infection. The negative relationship between vitamin D and complement C3 needs elucidation. Moreover, the increased proportion of B cells and decreased CD4+ cells in Vitamin D deficiency disrupt the immune response against HBV since the expected antibody response was not obtained despite the increase in B cell ratio. This indicates an influence of CD4+ cells for B cell functionality. In summary, sufficient levels of Vitamin D may lead to a sustained virological response that is debatable by artificially correcting the deficiency.

Phase 1b/2a randomized study of heterologous ChAdOx1-HBV/MVA-HBV therapeutic vaccination (VTP-300) as monotherapy and combined with low-dose nivolumab in virally-suppressed patients with chronic hepatitis B

BACKGROUND AND AIM

The induction of effective CD8+ T cells is thought to play a critical role in the functional cure of chronic hepatitis B (CHB). Additionally, the use of checkpoint inhibitors is being evaluated to overcome T cell dysfunction during CHB.

APPROACH AND RESULTS

A chimpanzee adenoviral vector (ChAdOx1-HBV) and a Modified vaccinia Ankara boost (MVA-HBV) encoding the inactivated polymerase, core, and S region from a consensus genotype C HBV were studied. The trial enrolled 55 patients with virally-suppressed CHB virus infection and HBsAg <4,000 IU/mL Group 1 received MVA-HBV intramuscularly (IM) on Day 0 and 28, Group 2 received ChAdOx1-HBV on Day 0/MVA-HBV on Day 28 (VTP-300), Group 3 received VTP-300 + low-dose nivolumab (LDN) on Day 28, and Group 4 received VTP-300 plus LDN with both injections. VTP-300 alone and in combination with LDN was well tolerated with no treatment-related serious adverse events. Reductions of HBsAg were demonstrated in the VTP-300 group 2: 3 of 18 patients with starting HBsAg < 50 IU/ml had durable log10 declines > 0.7 log10 2 months post last-dose. Group 3 (N=18) had reductions in HBsAg of 0.76 log10 and 0.80 log10 3 (p<0.001) at 2 and 7 months post last dose. Two developed persistent non-detectable HBsAg levels. CD4+ and CD8+ antigen-specific T cell responses were generated and there was a correlation between IFN-y ELISpot response and HBsAg decline in Group 2.

CONCLUSIONS

VTP-300 induced CD4+ and CD8+ T cells and lowered HBsAg in a subset of patients with baseline values below 100 IU/ml. The addition of LDN resulted in significant reduction in surface antigen. VTP-300 is a promising immunotherapeutic to move forward alone or in combination therapies.

IMPACT AND IMPLICATIONS

The induction of potent, durable CD8+ T cells may be critical to achieving a functional cure in chronic hepatitis B virus infection. A prime-boost immunotherapeutic consisting of an adenoviral-vector encoding hepatitis B antigens followed by a pox virus boost was shown to induce CD8+ T cells and to lower HBsAg in CHB patients, either alone or more impactfully when administered in conjunction with a checkpoint inhibitor. The use of immunotherapeutics CLINTRIALS: NCT047789.

Noninvasive models for the prediction of liver fibrosis in patients with chronic hepatitis B

OBJECTIVE

To evaluate the diagnostic accuracy of aspartate aminotransferase(AST)/ alanine transaminase (ALT), AST to platelet ratio index (APRI), fibrosis-4 score (FIB-4) and gamma-glutamyl transpeptidase to platelet count ratio (GPR) for hepatic fibrosis in patients with chronic hepatitis B (CHB).

METHODS

A total of 1210 CHB patients who underwent liver biopsy were divided into two groups: patients with no significant fibrosis (control group) and patients with significant fibrosis, and routine laboratory tests were retrospectively included. Logistic regression models were used for the prediction, and the area under the receiver operating characteristic (AUROC) was used to assess the diagnostic accuracy.

RESULTS

A total of 631 (52.1%) and 275 (22.7%) patients had significant fibrosis (≥ S2) and advanced fibrosis (≥ S3), respectively. The GPR showed significantly higher diagnostic accuracy than that of APRI, FiB-4, and AST/ALT to predict ≥ S2(significant fibrosis) and ≥ S3 fibrosis(advanced fibrosis), with an AUROC was 0.69 (95%CI: 0.66-0.71) and 0.72 (0.69-0.75), respectively. After stratified by the status of HBeAg ( positive or negative), GPR, APRI, and FiB-4 showed improved predicting performance for significant fibrosis and advanced fibrosis in HBeAg positive patients, with the most significant improvement was shown for GPR in predicting significant fibrosis (AUROC = 0.74, 95%CI: 0.70-0.78).

CONCLUSIONS

Among the four noninvasive models, GPR has the best performance in the diagnosis of hepatic fibrosis in CHB patients and is more valuable in HBeAg-positive patients.

The Adaptive Immune Response in Hepatitis B Virus-Associated Hepatocellular Carcinoma Is Characterized by Dysfunctional and Exhausted HBV-Specific T Cells

This systematic review investigates the immunosuppressive environment in HBV-associated hepatocellular carcinoma (HCC), characterized by dysfunctional and exhausted HBV-specific T cells alongside an increased infiltration of HBV-specific CD4+ T cells, particularly regulatory T cells (Tregs). Heightened expression of checkpoint inhibitors, notably PD-1, is linked with disease progression and recurrence, indicating its potential as both a prognostic indicator and a target for immunotherapy. Nevertheless, using PD-1 inhibitors has shown limited effectiveness. In a future perspective, understanding the intricate interplay between innate and adaptive immune responses holds promise for pinpointing predictive biomarkers and crafting novel treatment approaches for HBV-associated HCC.

HBsAg level defines different clinical phenotypes of HBeAg(-) chronic HBV infection related to HBV polymerase-specific CD8+ cell response quality

Background

HBe-antigen(Ag)-negative chronic hepatitis B virus (HBV) infection is characterized by little liver fibrosis progression and vigorous HBV-multispecific CD8+ T-cell response.

Aims

To assess whether HBsAg level could discriminate different HBeAg-negative chronic HBV infection subtypes with dissimilar quality of HBV-specific CD8+ T-cell response.

Methods

We recruited 63 HBeAg-negative chronic HBV infection patients in which indirect markers of liver inflammation/fibrosis, portal pressure, viral load (VL), and HBV-specific CD8+ cell effector function were correlated with HBsAg level.

Results

A positive linear trend between HBsAg level and APRI, liver stiffness (LS), liver transaminases, and HBV VL, and a negative correlation with platelet count were observed. Frequency of cases with HBV-specific CD8+ T-cell proliferation against at least two HBV epitopes was higher in HBsAg < 1,000 IU/ml group. CD8+ T-cell expansion after HBVpolymerase456-63-specific stimulation was impaired in HBsAg > 1,000 IU/ml group, while the response against HBVcore18-27 was preserved and response against envelope183-91 was nearly abolished, regardless of HBsAg level. Cases with preserved HBVpolymerase456-63 CD8+ cell response had lower LS/duration of infection and APRI/duration of infection rates. HBV-polymerase456-63-specific CD8+ T-cell proliferation intensity was negatively correlated with LS/years of infection ratio.

Conclusion

HBsAg > 1,000 IU/ml HBeAg-negative chronic HBV infection group shows indirect data of higher degree of inflammation, liver stiffness, and fibrosis progression speed, which are related to an impaired HBV-polymerase-specific CD8+ T-cell response.

Routine evaluation of HBV-specific T cell reactivity in chronic hepatitis B using a broad-spectrum T-cell epitope peptide library and ELISpot assay

BACKGROUND

The clinical routine test of HBV-specific T cell reactivity is still limited due to the high polymorphisms of human leukocyte antigens (HLA) in patient cohort and the lack of universal detection kit, thus the clinical implication remains disputed.

METHODS

A broad-spectrum peptide library, which consists of 103 functionally validated CD8+ T-cell epitopes spanning overall HBsAg, HBeAg, HBx and HBpol proteins and fits to the HLA polymorphisms of Chinese and Northeast Asian populations, was grouped into eight peptide pools and was used to establish an ELISpot assay for enumerating the reactive HBV-specific T cells in PBMCs. Totally 294 HBV-infected patients including 203 ones with chronic hepatitis B (CHB), 13 ones in acute resolved stage (R), 52 ones with liver cirrhosis (LC) and 26 ones with hepatocellular carcinoma (HCC) were detected, and 33 CHB patients were longitudinally monitored for 3 times with an interval of 3-5 months.

RESULTS

The numbers of reactive HBV-specific T cells were significantly correlated with ALT level, HBsAg level, and disease stage (R, CHB, LC and HCC), and R patients displayed the strongest HBV-specific T cell reactivity while CHB patients showed the weakest one. For 203 CHB patients, the numbers of reactive HBV-specific T cells presented a significantly declined trend when the serum viral DNA load, HBsAg, HBeAg or ALT level gradually increased, but only a very low negative correlation coefficient was defined (r = - 0.21, - 0.21, - 0.27, - 0.079, respectively). Different Nucleotide Analogs (NUCs) did not bring difference on HBV-specific T cell reactivity in the same duration of treatment. NUCs/pegIFN-α combination led to much more reactive HBV-specific T cells than NUCs monotherapy. The dynamic numbers of reactive HBV-specific T cells were obviously increasing in most CHB patients undergoing routine treatment, and the longitudinal trend possess a high predictive power for the hepatitis progression 6 or 12 months later.

CONCLUSION

The presented method could be developed into an efficient reference method for the clinical evaluation of cellular immunity. The CHB patients presenting low reactivity of HBV-specific T cells have a worse prognosis for hepatitis progression and should be treated using pegIFN-α to improve host T-cell immunity.

Higher end-of-treatment HBsAg levels is associated with later onset but not severe relapse in HBeAg-negative chronic hepatitis B patients stopping antivirals

BACKGROUND

Quantitative hepatitis B surface antigen (qHBsAg) level at end-of-treatment (EOT) predict clinical relapse (CR) after nucleos(t)ide analogues (Nuc) in chronic hepatitis B(CHB) patients. It is unclear if higher EOT qHBsAg leads to earlier onset or more severe off-Nuc CR.

AIM

This large cohort study investigates the association between EOT qHBsAg and CR onset/severity.

METHODS

This study enrolled HBeAg-negative CHB patients who had achieved undetectable HBV DNA for over 1 year after receiving Nuc therapy before discontinuation. The EOT qHBsAg level was categorised into three groups: <100, 100-999, ≥1000 IU/mL. The study assessed the predictability of qHBsAg levels for CR, and analysed and compared the incidence, time to onset and severity of CR among these three groups.

RESULTS

Patients with higher EOT qHBsAg showed a higher incidence of CR (≥1000, 100-999, <100 IU/mL: 73%, 65%, and 38%, p < 0.01) but a later onset of CR (median time to CR: 35, 33 and 27 weeks, p < 0.01). The predictabilities of EOT qHBsAg for CR were greater in patients aged <50-year-old or with genotype C than in those aged ≥50-year-old or with genotype B. There's no correlation between EOT qHBsAg level and ALT folds at CR (Pearson correlation coefficient: r = -0.03, p = 0.35). EOT qHBsAg was neither a predictor for severe hepatitis flare nor a predictor for hepatic decompensation.

CONCLUSIONS

Predictability using EOT qHBsAg levels for CR differed in subgroups of age and genotypes. Higher EOT qHBsAg levels correlate with higher incidence but later onset of CR. No correlation between EOT qHBsAg and relapse severity was observed.

IL-2 produced by HBV-specific T cells as a biomarker of viral control and predictor of response to PD-1 therapy across clinical phases of chronic hepatitis B

BACKGROUND

There are no immunological biomarkers that predict control of chronic hepatitis B (CHB). The lack of immune biomarkers raises concerns for therapies targeting PD-1/PD-L1 because they have the potential for immune-related adverse events. Defining specific immune functions associated with control of HBV replication could identify patients likely to respond to anti-PD-1/PD-L1 therapies and achieve a durable functional cure.

METHODS

We enrolled immunotolerant, HBeAg+ immune-active (IA+), HBeAg- immune-active (IA-), inactive carriers, and functionally cured patients to test ex vivo PD-1 blockade on HBV-specific T cell functionality. Peripheral blood mononuclear cells were stimulated with overlapping peptides covering HBV proteins +/-α-PD-1 blockade. Functional T cells were measured using a 2-color FluoroSpot assay for interferon-γ and IL-2. Ex vivo functional restoration was compared to the interferon response capacity assay, which predicts overall survival in cancer patients receiving checkpoint inhibitors.

RESULTS

Ex vivo interferon-γ+ responses did not differ across clinical phases. IL-2+ responses were significantly higher in patients with better viral control and preferentially restored with PD-1 blockade. Inactive carrier patients displayed the greatest increase in IL-2 production, which was dominated by CD4 T cell and response to the HBcAg. The interferon response capacity assay significantly correlated with the degree of HBV-specific T cell restoration.

CONCLUSIONS

IL-2 production was associated with better HBV control and superior to interferon-γ as a marker of T cell restoration following ex vivo PD-1 blockade. Our study suggests that responsiveness to ex vivo PD-1 blockade, or the interferon response capacity assay, may support stratification for α-PD-1 therapies.

Recent advances in understanding T cell activation and exhaustion during HBV infection

Chronic hepatitis B virus (HBV) infection remains a major public health concern globally, and T cell responses are widely believed to play a pivotal role in mediating HBV clearance. Accordingly, research on the characteristics of HBV-specific T cell responses, from activation to exhaustion, has advanced rapidly. Here, we summarize recent developments in characterizing T cell immunity in HBV infection by reviewing basic and clinical research published in the last five years. We provide a comprehensive summary of the mechanisms that induce effective anti-HBV T cell immunity, as well as the latest developments in understanding T cell dysfunction in chronic HBV infection. Furthermore, we briefly discuss current novel treatment strategies aimed at restoring anti-HBV T cell responses.

A MicroRNA-Based Method for High-Viremia Detection-A New Approach on a Romanian Lot of Chronically Infected Patients with Hepatitis B Virus

The HBV (hepatitis B virus) infection is intended for elimination, but evaluating patients is both costly and insufficiently applied in several countries. An expensive analysis in Romania is HBV-DNA quantification, with a limited prognostic potential. Our study intended to find new predictors for high viremia in HBV patients, using molecules involved in the multiple assessment of various HBV complications, such as microRNAs. A total of 61 subjects (48 patients with chronic HBV infection and 13 healthy subjects) were generally evaluated. Using a RT-PCR method, with a 2-ΔΔCT algorithm, we detected the expressions of miR-122 and miR-146a in 33 subjects. MiR-21 was the internal control. The results were analyzed with the R 4.2.2. software. Kruskal-Wallis's comparisons, Spearman correlations, and several logistic regression methods were applied. The median age of the patients was over 40 years. Without microRNAs, we could not obtain a good prediction formula. The combination of miR-122 and age proved to be the best prediction method for high viremia, with an AUC of 0.827, and a sensitivity of 89.5%. This is the first study which included age and miR-122 as independent predictors for high viremia in Romanian HBV-positive patients. MiR-122 is a new potential biomarker in the evaluation of Romanian patients.

Guidance on treatment endpoints and study design for clinical trials aiming to achieve cure in chronic hepatitis B and D: Report from the 2022 AASLD-EASL HBV-HDV Treatment Endpoints Conference

Representatives from academia, industry, regulatory agencies, and patient advocacy groups convened under the American Association for the Study of Liver Diseases (AASLD) and the European Association for the Study of the Liver (EASL) in June 2022 with the primary goal of achieving consensus on chronic HBV and HDV treatment endpoints to guide clinical trials aiming to "cure" HBV and HDV. Conference participants reached an agreement on some key points. The preferred primary endpoint for phase II/III trials evaluating finite treatments for chronic hepatitis B (CHB) is a "functional" cure, defined as sustained HBsAg loss and HBV DNA less than the lower limit of quantitation (LLOQ) 24 weeks off-treatment. An alternate endpoint would be "partial cure" defined as sustained HBsAg level <100 IU/mL and HBV DNA Collapse

Key Words

• HBV
• HDV
• diagnosis

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MESH Headings Collapse

Grants

• 001 World Health Organization

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Affiliation(s)

Marc G Ghany Liver Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
Maria Buti Liver Unit, Vall d'Hebron University Hospital and CIBEREHD del Instituto Carlos III, Barcelona, Spain
Pietro Lampertico Division of Gastroenterology and Hepatology, Milan, Italy; CRC "A. M. and A. Migliavacca" Center for Liver Disease, Milan, Italy
Hannah M Lee Department of Gastroenterology, Hepatology and Nutrition, Stravitz Sanyal Institute for Liver Disease and Metabolic Health, Virginia Commonwealth University, Richmond, Virginia, USA

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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. Cytokine production was also evaluated in HBV peptide-stimulated T cell cultures, in the presence or absence of antioxidant, polyphenolic, PD-1/PD-L1 inhibitor and TLR-8 agonist compounds and the effect on HBV-specific responses was further validated on additional 24 HLA-A2 negative CHB patients.

RESULTS

Severely exhausted HBV-specific CD8 T cell subsets with high expression of inhibitory receptors, such as PD-1, TOX and CD39, were detected only in a subgroup of chronic viraemic patients. Conversely, a large predominance of functionally more efficient HBV-specific CD8 T cell subsets with lower expression of coinhibitory molecules and better response to in vitro immune modulation, typically detected after resolution of infection, was also observed in a proportion of chronic viraemic HBV patients. Importantly, the same subset of patients who responded more efficiently to in vitro immune modulation identified by HBV-specific CD8 T cell analysis were also identified by staining total CD8 T cells with PD-1, TOX, CD127 and Bcl-2.

CONCLUSIONS

The possibility to distinguish patient cohorts with different capacity to respond to immune modulatory compounds in vitro by a simple analysis of the phenotypic CD8 T cell exhaustion profile deserves evaluation of its clinical applicability.

Overview of New Targets for Hepatitis B Virus: Immune Modulators, Interferons, Bifunctional Peptides, Therapeutic Vaccines and Beyond

Nucleos(t)ide analogs are the cornerstone of treatment against hepatitis B virus; however, they have no direct effect on its transcriptional template (ie, covalently closed circular DNA) and so functional cure is rarely achieved. Over recent years, there has been a significant improvement in our understanding of the viral life cycle and its mechanisms of immune evasion. In this review article, we will explore novel therapeutic targets, discuss the latest data from clinical trials, and highlight future research priorities.

Functional Cure of Chronic Hepatitis B with Antiviral Treatment in Children having High-level Viremia and Normal or Mildly Elevated Serum Aminotransferase

Background and Aims

There is a lack of data supporting the notion that antiviral treatments can benefit children with chronic hepatitis B (CHB) having high viremia and normal or mildly elevated serum alanine aminotransferase (ALT) levels. We aimed to analyze the efficacy of antiviral treatments in children with CHB and explore the factors associated with functional cure.

Methods

Forty-eight children with CHB having high viremia and normal or mildly elevated serum ALT levels were screened in this real-world study. Thirty-two children received either interferon-alpha (IFN-α) monotherapy, IFN-α therapy with a nucleoside analog (NA) add-on, or IFN-α and NA combination therapy. The 16 children in the control group did not receive antiviral treatment. All 48 children were available for follow-up assessments for the entire 36-month study period. We identified a functional cure with respect to hepatitis B virus (HBV) DNA loss, loss /seroconversion of circulating hepatitis B e antigen (HBeAg), and loss of hepatitis B surface antigen (HBsAg) with or without seroconversion. Cox regression analysis was employed to evaluate the factors that may have influenced the functional cure.

Results

After 36 months, the cumulative functional cure rate was 56.25% (18/32) in the treated group and 0% (0/16) in the control group (p<0.001). In the treated group, the serum HBV DNA levels declined rapidly at the end of a 6-month visit and the cured children achieved a loss rate of 100% (18/18) within 16 months of beginning treatment, compared with 64.29% (9/14) of the uncured children (p<0.001). The rates of HBeAg seroconversion were significantly higher among the cured children than among the uncured children (p<0.001). All 16 children in the control group maintained high levels of serum HBV DNA and were positive for both serum HBeAg and HBsAg during the entire 36 months of the study period. Functional cure was associated with younger ages (1-6 vs. 7-14 years, p=0.013), CD8+ T lymphocyte counts (p=0.013), and B lymphocyte counts (p=0.003). No serious adverse events were observed.

Conclusions

Antiviral treatment achieved a functional cure of CHB in a high proportion of children having high-level viremia and normal or mildly elevated ALT levels. Younger age and high peripheral lymphocyte counts were associated with this functional cure.

Metabolic interventions improve HBV envelope-specific T-cell responses in patients with chronic hepatitis B

BACKGROUND

Restoration of HBV-specific T cell immunity is a promising approach for the functional cure of chronic Hepatitis B (CHB), necessitating the development of valid assays to boost and monitor HBV-specific T cell responses in patients with CHB.

METHODS

We analyzed hepatitis B virus (HBV) core- and envelope (env)-specific T cell responses using in vitro expanded peripheral blood mononuclear cells (PBMCs) from patients with CHB exhibiting different immunological phases, including immune tolerance (IT), immune activation (IA), inactive carrier (IC), and HBeAg-negative hepatitis (ENEG). Additionally, we evaluated the effects of metabolic interventions, including mitochondria-targeted antioxidants (MTA), polyphenolic compounds, and ACAT inhibitors (iACAT), on HBV-specific T-cell functionality.

RESULTS

We found that HBV core- and env-specific T cell responses were finely coordinated and more profound in IC and ENEG than in the IT and IA stages. HBV env-specific T cells were more dysfunctional but prone to respond to metabolic interventions using MTA, iACAT, and polyphenolic compounds than HBV core-specific T-cells. The responsiveness of HBV env-specific T cells to metabolic interventions can be predicted by the eosinophil (EO) count and the coefficient of variation of red blood cell distribution width (RDW-CV).

CONCLUSION

These findings may provide valuable information for metabolically invigorating HBV-specific T-cells to treat CHB.

Role of CXCR5+ CD8+ T cells in human hepatitis B virus infection

The replication of HBV in hepatocytes can be effectively inhibited by lifelong antiviral therapy. Because of the long-term presence of HBV reservoirs, the virus rebound frequently occurs once the treatment is stopped, which poses a considerable obstacle to the complete removal of the virus. In terms of gene composition, regulation of B cell action and function, CXCR5+ CD8+ T cells are similar to CXCR5+ CD4+ T follicular helper cells, while these cells are characterized by elevated programmed cell death 1 and cytotoxic-related proteins. CXCR5+ CD8+ T cells are strongly associated with progression in inflammatory and autoimmune diseases. In addition, CXCR5 expression on the surface of CD8+ T cells is mostly an indicator of memory stem cell-like failure in progenitor cells in cancer that are more responsive to immune checkpoint blocking therapy. Furthermore, the phenomena have also been demonstrated in some viral infections, highlighting the duality of the cellular immune response of CXCR5+ CD8+ T cells. This mini-review will focus on the function of CXCR5+ CD8+ T cells in HBV infection and discuss the function of these CD8+ T cells and the potential of associated co-stimulators or cytokines in HBV therapeutic strategies.

Differential response of HBV envelope-specific CD4 + T cells is related to HBsAg loss after stopping nucleos(t)ide analogue therapy

BACKGROUND AND AIM

Long-term maintenance of viral control, even HBsAg loss, remains a challenge for chronic hepatitis B (CHB) patients undergoing nucleos(t)ide analogue (NA) discontinuation. This study aimed to investigate the relationship between HBV-specific T-cell responses targeting peptides spanning the whole proteome and clinical outcomes in CHB patients after NA discontinuation.

APPROACH AND RESULTS

Eighty-eight CHB patients undergoing NA discontinuation were classified as responders (remained relapse-free up to 96 weeks) or relapsers (relapsed patients who underwent NA retreatment for up to 48 weeks and reachieved stable viral control). HBV-specific T-cell responses were detected at baseline and longitudinally throughout the follow-up. We found responders had a greater magnitude of HBV polymerase (Pol)-specific T-cell responses than relapsers at baseline. After long-term NA discontinuation, simultaneously enhanced HBV Core-induced and Pol-induced responses were observed in responders. Particularly, responders with HBsAg loss possessed enhanced HBV Envelope (Env)-induced responses after short-term and long-term follow-up. Notably, CD4 + T cells accounted for the predominance of HBV-specific T-cell responses. Correspondingly, CD4-deficient mice showed attenuated HBV-specific CD8 + T-cell responses, reduced HBsAb-producing B cells, and delayed HBsAg loss; in contrast, in vitro addition of CD4 + T cells promoted HBsAb production by B cells. Besides, IL-9, rather than PD-1 blockade, enhanced HBV Pol-specific CD4 + T-cell responses.

CONCLUSION

HBV-specific CD4 + T-cell responses induced by the targeted peptide possess specificities for long-term viral control and HBsAg loss in CHB patients undergoing NA discontinuation, indicating that CD4 + T cells specific to distinct HBV antigens may endow with divergent antiviral potential.

Cell Culture Systems for Studying Hepatitis B and Hepatitis D Virus Infections

The hepatitis B virus (HBV) and hepatitis D virus (HDV) infections cause liver disease, including hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). HBV infection remains a major global health problem. In 2019, 296 million people were living with chronic hepatitis B and about 5% of them were co-infected with HDV. In vitro cell culture systems are instrumental in the development of therapeutic targets. Cell culture systems contribute to identifying molecular mechanisms for HBV and HDV propagation, finding drug targets for antiviral therapies, and testing antiviral agents. Current HBV therapeutics, such as nucleoside analogs, effectively suppress viral replication but are not curative. Additionally, no effective treatment for HDV infection is currently available. Therefore, there is an urgent need to develop therapies to treat both viral infections. A robust in vitro cell culture system supporting HBV and HDV infections (HBV/HDV) is a critical prerequisite to studying HBV/HDV pathogenesis, the complete life cycle of HBV/HDV infections, and consequently identifying new therapeutics. However, the lack of an efficient cell culture system hampers the development of novel antiviral strategies for HBV/HDV infections. In vitro cell culture models have evolved with significant improvements over several decades. Recently, the development of the HepG2-NTCP sec+ cell line, expressing the sodium taurocholate co-transporting polypeptide receptor (NTCP) and self-assembling co-cultured primary human hepatocytes (SACC-PHHs) has opened new perspectives for a better understanding of HBV and HDV lifecycles and the development of specific antiviral drug targets against HBV/HDV infections. We address various cell culture systems along with different cell lines and how these cell culture systems can be used to provide better tools for HBV and HDV studies.

Individual Epitope-Specific CD8+ T Cell Immune Responses Are Shaped Differently during Chronic Viral Infection

A hallmark in chronic viral infections are exhausted antigen-specific CD8⁺ T cell responses and the inability of the immune system to eliminate the virus. Currently, there is limited information on the variability of epitope-specific T cell exhaustion within one immune response and the relevance to the T cell receptor (TCR) repertoire. The aim of this study was a comprehensive analysis and comparison of three lymphocytic choriomeningitis virus (LCMV) epitope-specific CD8⁺ T cell responses (NP396, GP33 and NP205) in a chronic setting with immune intervention, e.g., immune checkpoint inhibitor (ICI) therapy, in regard to the TCR repertoire. These responses, though measured within the same mice, were individual and independent from each other. The massively exhausted NP396-specific CD8⁺ T cells revealed a significantly reduced TCR repertoire diversity, whereas less-exhausted GP33-specific CD8⁺ T cell responses were rather unaffected by chronicity in regard to their TCR repertoire diversity. NP205-specific CD8⁺ T cell responses showed a very special TCR repertoire with a prominent public motif of TCR clonotypes that was present in all NP205-specific responses, which separated this from NP396- and GP33-specific responses. Additionally, we showed that TCR repertoire shifts induced by ICI therapy are heterogeneous on the epitope level, by revealing profound effects in NP396-, less severe and opposed effects in NP205-, and minor effects in GP33-specific responses. Overall, our data revealed individual epitope-specific responses within one viral response that are differently affected by exhaustion and ICI therapy. These individual shapings of epitope-specific T cell responses and their TCR repertoires in an LCMV mouse model indicates important implications for focusing on epitope-specific responses in future evaluations for therapeutic approaches, e.g., for chronic hepatitis virus infections in humans.

CRISPR/Cas9 for hepatitis B virus infection treatment

Hepatitis B virus (HBV) infection remains a global health challenge. Despite the availability of effective preventive vaccines, millions of people are at risk of cirrhosis and hepatocellular carcinoma. Current drug therapies inhibit viral replication, slow the progression of liver fibrosis and reduce infectivity, but they rarely remove the covalently sealed circular DNA (cccDNA) of the virus that causes HBV persistence. Alternative treatment strategies, including those based on CRISPR/cas9 knockout virus gene, can effectively inhibit HBV replication, so it has a good prospect. During chronic infection, some virus gene knockouts based on CRISPR/cas9 may even lead to cccDNA inactivation. This paper reviews the progress of different HBV CRISPR/cas9, vectors for delivering to the liver, and the current situation of preclinical and clinical research.

Blockade of CCR4 breaks immune tolerance in chronic hepatitis B patients by modulating regulatory pathways

BACKGROUND

Immunotargets including checkpoint inhibitors and toll-like receptor 8 agonists have recently gained attention for the recovery of hepatitis B virus (HBV)-specific T cell exhaustion in chronic hepatitis B(CHB). Chemokine receptors have a similar significant role during viral infections; however, their role in CHB remains poorly understood. Therefore, in this study we evaluated the role of chemokine receptor 4 (CCR4) in deriving immunosuppression during CHB.

METHODS

We characterized CCR4+CD8+ T cells in CHB and identified their involvement in immunosuppression. Further, we examined if CCR4 blockade with mogamulizumab antibody can recover the functional exhaustion in HBsAg-specific T cells.

RESULTS

CHB patients exhibit higher frequency of CCR4+CD8+ T cells that increase with higher HBsAg levels and fibrosis scores. In vitro, HBs antigen triggers CCR4 expression. These cells express multiple inhibitory receptors and exhibit immunosuppressive functions by producing excessive immunoregulatory cytokines IL-4, IL-5, IL-10 and TGF-β1. CCR4 Blockade significantly boosted HBsAg-specific antiviral-cytokine production(IFN-γ, TNF-α and IL-21) in T cells through enhancing their proliferation capacity and polarizing these cells towards T helper 1(Th1) and T follicular helper cells(T_FH) in case of CD4 cells, and cytotoxic T cell 1(TC1) and cytotoxic T follicular(T_CF) cells in case of CD8. Cytotoxic potential was improved, while no induction of immunosuppressive-cytokines was seen after anti-CCR4 treatment thereby eliminating the risk of treatment-induced immunosuppression. CCR4 blockade inhibited the development and effector function of Tregs by controlling their expansion and TGF-β1 production preventing Tregs-induced immunotolearance.

CONCLUSIONS

CCR4 blockade reconstitutes antiviral immune response in T cells and limits the immunosuppressive functions of Tregs, representing them as a promising immunotherapeutic target for functional cure of CHB.

Assessing the chronic hepatitis B adaptive immune response by profiling specific T-cell receptor repertoire

Challenges in assessing hepatitis B virus (HBV)-specific T cell immunity as an immunological biomarker still remain in chronic hepatitis B (CHB), such as the requirement of large quantities of cells. This study aims to conveniently assess HBV-specific T cells immunity in chronic HBV infected patients. We obtained T cell receptor β chains (TCRβs) from public databases and six acute hepatitis B patients to establish an HBV-specific TCRβs dataset. For some TCRs from one AHB patient, their specificities and epitopes were verified. The potential HBV-specific TCRβs from CHB patients were analyzed using GLIPH2 and established dataset. By analyzing two antiviral therapy cohorts including 42 CHB patients, we showed that individuals with better therapy response may depend more on newly emerging potential HBV-specific TCRβs. In a cross-sectional study containing 207 chronic HBV infected patients, the results exhibited that the characteristics of potential HBV-specific clusters were divergent between CHB and hepatocellular carcinoma patients. Our strategy could profile potential HBV-specific TCRβ repertoire using a small blood sample, which will complement traditional methods for assessing the HBV-specific T cell immunity.

The surge of HBsAb level in a HBsAg-negative ES-SCLC patient after anlotinib plus atezolizumab treatment: A case report

Small-cell lung cancer (SCLC) is a poorly differentiated neuroendocrine tumor with endocrine function. For decades, chemotherapy and immune checkpoint inhibitors (ICIs) have been the first-line treatment options. Because of its ability to normalize tumor vessels, anlotinib is recommended as a novel therapy as a third-line treatment. A combination of anti-angiogenic drugs and ICIs can effectively and safely benefit advanced cancer patients. However, immune-related side effects caused by ICIs are common. Hepatitis B virus (HBV) reactivation and hepatitis are common during immunotherapy in patients with chronic HBV infection. A 62-year-old man with ES-SCLC who had brain metastasis was described in this case. It is unusual for a HBsAg-negative patient to develop an increase in HBsAb after receiving atezolizumab immunotherapy. Although some researchers have reported the functional cure of HBV by PD-L1 antibody, this is the first case that showed a sustained increased in HBsAb level after anti-PD-L1 therapy. It is related with CD4+ and CD8+ T cells activation and HBV infection microenvironment. Importantly, this could provide a solution to insufficient protective antibody production after vaccination as well as a therapeutic opportunity for HBV patients with cancers.

HBV Core-specific CD4+ T cells correlate with sustained viral control upon off-treatment in HBeAg-positive chronic hepatitis B patients

BACKGROUND & AIMS

Treatment with nucleos(t)ide analogue (NA) efficiently suppresses viral replication in patients with chronic HBV infection, yet HBV relapse frequently upon NA withdrawal; the detailed immunomodulatory compounds for sustained viral control of HBV upon NA interruption have yet to be fully clarified. This study aimed to elucidate the role of T cells specific for distinct HBV peptides in sustained response upon discontinuation of antiviral treatment.

METHODS

A total of 48 patients with HBeAg-positive chronic hepatitis B receiving NA treatment and withdrawal were included longitudinally in a retrospective and prospective cohort. Enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine staining (ICS) assays were performed to detect IFN-γ producing HBV-specific T cells following stimulation with overlapping peptides covering the whole HBV genome after 10 days of in vitro expansion.

RESULTS

ICS assays revealed that T cells specific for HBV Core and Polymerase induced more robust IFN-γ responses compared to envelope and HBx. Notably, at the time of NA discontinuation, the intensity and breadth of HBV Core peptides-induced responses, predominately targeted by CD4⁺ T cells but not CD8⁺ T cells, were associated with sustained viral control upon off-treatment. Further exploration of longitudinal features in patients with sustained viral control revealed that the breadth of HBV-specific T cell responses does not increase following treatment cessation.

CONCLUSION

This report emphasizes the essential role of HBV Core-specific CD4⁺ T cells in sustained response after therapy withdrawal, indicating it is a potential candidate for immunotherapeutic approaches in chronic HBV patients.

Liver-resident CD8+ T cells in viral hepatitis: not always good guys

More than twenty years ago, non-HBV-specific CD8+ T cells were found to contribute to liver immunopathology in chronic HBV infection, while HBV-specific CD8+ T cells were noted to contribute to viral control. The role of HBV-specific CD8+ T cells in viral control and the mechanisms of their failure in persistent infection have been intensively studied during the last two decades, but the exact nature of nonspecific bystander CD8+ T cells that contribute to immunopathology has remained elusive. In this issue of the JCI, Nkongolo et al. report on their application of two methodological advances, liver sampling by fine-needle aspiration (FNA) and single-cell RNA sequencing (scRNA-Seq), to define a liver-resident CD8+ T cell population that was not virus specific but associated with liver damage, thus representing hepatotoxic bystander CD8+ T cells.

Single-cell RNA sequencing reveals intrahepatic and peripheral immune characteristics related to disease phases in HBV-infected patients

OBJECTIVE

A comprehensive immune landscape for HBV infection is pivotal to achieve HBV cure.

DESIGN

We performed single-cell RNA sequencing of 2 43 000 cells from 46 paired liver and blood samples of 23 individuals, including six immune tolerant, 5 immune active (IA), 3 acute recovery (AR), 3 chronic resolved and 6 HBV-free healthy controls (HCs). Flow cytometry and histological assays were applied in a second HBV cohort for validation.

RESULTS

Both IA and AR were characterised by high levels of intrahepatic exhausted CD8+ T (Tex) cells. In IA, Tex cells were mainly derived from liver-resident GZMK+ effector memory T cells and self-expansion. By contrast, peripheral CX3CR1+ effector T cells and GZMK+ effector memory T cells were the main source of Tex cells in AR. In IA but not AR, significant cell-cell interactions were observed between Tex cells and regulatory CD4+ T cells, as well as between Tex and FCGR3A+ macrophages. Such interactions were potentially mediated through human leukocyte antigen class I molecules together with their receptors CANX and LILRBs, respectively, contributing to the dysfunction of antiviral immune responses. By contrast, CX3CR1+GNLY+ central memory CD8+ T cells were concurrently expanded in both liver and blood of AR, providing a potential surrogate marker for viral resolution. In clinic, intrahepatic Tex cells were positively correlated with serum alanine aminotransferase levels and histological grading scores.

CONCLUSION

Our study dissects the coordinated immune responses for different HBV infection phases and provides a rich resource for fully understanding immunopathogenesis and developing effective therapeutic strategies.

Abnormally primed CD8 T cells: The Achilles' heel of CHB

Chronic hepatitis B virus (HBV) infection continues to be a significant public health challenge, and more than 250 million people around world are infected with HBV. The clearance of HBV with virus-specific CD8 T cells is critical for a functional cure. However, naïve HBV-specific CD8 T cells are heavily hindered during the priming process, and this phenomenon is closely related to abnormal cell and signal interactions in the complex immune microenvironment. Here, we briefly summarize the recent progress in understanding the abnormal priming of HBV-specific CD8 T cells and some corresponding immunotherapies to facilitate their functional recovery, which provides a novel perspective for the design and development of immunotherapy for chronic HBV infection (CHB). Finally, we also highlight the balance between viral clearance and pathological liver injury induced by CD8 T-cell activation that should be carefully considered during drug development.

Hepatitis B and Hepatitis D Viruses: A Comprehensive Update with an Immunological Focus

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are highly prevalent viruses estimated to infect approximately 300 million people and 12-72 million people worldwide, respectively. HDV requires the HBV envelope to establish a successful infection. Concurrent infection with HBV and HDV can result in more severe disease outcomes than infection with HBV alone. These viruses can cause significant hepatic disease, including cirrhosis, fulminant hepatitis, and hepatocellular carcinoma, and represent a significant cause of global mortality. Therefore, a thorough understanding of these viruses and the immune response they generate is essential to enhance disease management. This review includes an overview of the HBV and HDV viruses, including life cycle, structure, natural course of infection, and histopathology. A discussion of the interplay between HDV RNA and HBV DNA during chronic infection is also included. It then discusses characteristics of the immune response with a focus on reactions to the antigenic hepatitis B surface antigen, including small, middle, and large surface antigens. This paper also reviews characteristics of the immune response to the hepatitis D antigen (including small and large antigens), the only protein expressed by hepatitis D. Lastly, we conclude with a discussion of recent therapeutic advances pertaining to these viruses.

Immunological biomarker discovery in cure regimens for chronic hepatitis B virus infection

There have been unprecedented advances in the identification of new treatment targets for chronic hepatitis B that are being developed with the goal of achieving functional cure in patients who would otherwise require lifelong nucleoside analogue treatment. Many of the new investigational therapies either directly target the immune system or are anticipated to impact immunity indirectly through modulation of the viral lifecycle and antigen production. While new viral biomarkers (HBV RNA, HBcAg, small, middle, large HBs isoforms) are proceeding through validation steps in clinical studies, immunological biomarkers are non-existent outside of clinical assays for antibodies to HBs, HBc and HBe. To develop clinically applicable immunological biomarkers to measure mechanisms of action, inform logical combination strategies, and guide clinical management for use and discontinuation of immune-targeting drugs, immune assays must be incorporated into phase I/II clinical trials. This paper will discuss the importance of sample collection, the assays available for immunological analyses, their advantages/disadvantages and suggestions for their implementation in clinical trials. Careful consideration must be given to ensure appropriate immunological studies are included as a primary component of the trial with deeper immunological analysis provided by ancillary studies. Standardising immunological assays and data obtained from clinical trials will identify biomarkers that can be deployed in the clinic, independently of specialised immunology laboratories.

Risk prediction models for hepatocellular carcinoma in chronic hepatitis B patients on antiviral therapy: A meta-analysis

BACKGROUND AND AIMS

The risk prediction of hepatocellular carcinoma (HCC) in patients with chronic hepatitis B (CHB) is a challenge especially in the era of antiviral therapy. The aim of this meta-analysis was to comprehensively evaluate the performance of existing HCC prediction scores in HCC prediction on antivirals.

METHODS

We searched PubMed, Web of Science and Cochrane Library for relevant prospective studies from the inception to August 24, 2021. The areas under the receiver operating characteristics (AUROCs) and their relevant 95% confidence intervals (CIs) of the risk prediction models were calculated.

RESULTS

Nine eligible articles with 21561 patients (HCC developed in 947patients, 4.39%; mean follow-up duration: 5 years) and 14 predictive risk scores were included. The pooled AUROC of all included scores for 3-year and 5-year prediction of HCC was 0.72 (95%CI 0.68-0.76) and 0.80 (95%CI 0.76-0.83), with the corresponding sensitivity of 0.84 (95% CI 0.71-0.92) and 0.91(95% CI 0.86-0.95) and specificity of 0.46 (95% CI 0.30-0.63) and 0.48 (95% CI 0.37-0.59), respectively. All the 14 prediction models, as a whole, performed well in different populations, whether they include factor cirrhotic status or not; while those integrated viral load were less accurate (sensitivity 0.78, specificity of 0.57).

CONCLUSIONS

In patients with CHB on antivirals, the scores included in our meta-analysis have been proven to be useful for mid-long term HCC prediction. Viral load seems not useful, whereas cirrhosis and its objective surrogates remain the predominant components. These models are expected to translate clinical benefits if used in complementarity with regular HCC surveillance.

Adenosine Triphosphate in Serum as a Promising Biomarker for Differential Diagnosis of Hepatitis B Disease Progression

The need to be diagnosed with liver biopsy makes the clinical progression of chronic HBV infection diagnosis a challenge. Existing HBV serum biochemical assays are used throughout clinical but have limited effects. Studies have shown that mitochondrial function is tightly coupled to HBV infection. Here, we verified the diagnostic value of serum Adenosine Triphosphate (ATP) as a potential marker for differential HBV infection progress by detecting the level of ATP in the serum from a wide spectrum of HBV-infected populations, and confirmed the role of ATP in the deterioration of HBV infection-related diseases through HBV-infected cells and mouse models. The results showed that there were significantly lower serum ATP levels in HBeAg-positive CHB patients compared with healthy controls. And during the progression of CHB to liver cirrhosis and hepatocellular carcinoma, the ATP level was increased but not higher than healthy controls. The area under the curve (AUC) of serum ATP was 0.9063 to distinguish HBeAg-positive CHB from healthy, and another AUC was 0.8328 in the CHB against the HCC group. Preliminary exploration of the mechanism indicated that the decline of serum ATP was due to impaired mitochondria in CHB patients. Our data provide evidence that serum ATP distinguishes the various progress of HBV infection-related diseases and expands diagnostic biomarkers for HBeAg-positive CHB patients with healthy controls.

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. In this perspective, a detailed understanding of the different causes of T cell exhaustion is essential for the design of successful functional T cell correction strategies. Among many different mechanisms which are widely believed to play a role in T cell dysfunction, persistent T cell exposure to high antigen burden, in particular HBsAg, is expected to influence T cell differentiation and function. Definitive evidence of the possibility to improve anti-viral T cell functions by antigen decline is, however, still lacking. This review aims at recapitulating what we have learned so far on the complex T cell–viral antigen interplay in chronic HBV infection.