Lamivudine treatment can restore T cell responsiveness in chronic hepatitis B

IP10 and Anti-HBc can Predict Virological Relapse and HBsAg Loss in Chronic Hepatitis B Patients after Nucleos(t)ide Analog Discontinuation

INTRODUCTION

To assess predictive ability of serum interferon-inducible protein 10 (IP10) and hepatitis B core antibody (anti-HBc) levels for virological relapse (VR) and hepatitis B surface antigen (HBsAg) loss after nucleos(t)ide analog (NA) discontinuation.

METHODS

In this multicenter prospective study, overall 139 patients were followed up for 24 months after NA discontinuation.

RESULTS

End of treatment (EOT) IP10 and anti-HBc were 29.2 (5.1-66.4) pg/mL and 193.6 (136.9-221.4) IU/mL. EOT IP10 and anti-HBc were independent predictors for VR and HBsAg loss in Cox regression analysis. Cumulative rates of VR in patients with EOT IP10 > 26.99 pg/mL was 31.9% (vs. 70.1%, hazard ratio [HR] 2.998, p < 0.001). Cumulative incidences of VR in patients with EOT anti-HBc ≤141.35 IU/mL was 49.1% (vs. 60.6%, HR 2.99, p < 0.001). Cumulative probabilities of VR was 16.7% in patients with EOT IP10 > 26.99 pg/mL plus anti-HBc ≤141.35 IU/mL (vs. 73.6%, HR 6.464, p < 0.001). Cumulative probabilities of HBsAg loss in patients with EOT IP10 > 93.5 pg/mL was 46.2% (vs. 4.7%, HR 10.94, p < 0.001). Cumulative probabilities of HBsAg loss in patients with EOT anti-HBc ≤78.42 IU/mL were 47.1% (vs. 5%, HR 12.27, p < 0.001). Patients with EOT IP10 > 93.5 pg/mL plus anti-HBc ≤78.42 IU/mL had the highest 24-month cumulative HBsAg loss rate (53.8% vs. 4%, HR 16.83, p < 0.001).

CONCLUSION

High EOT IP10 and low EOT anti-HBc levels were related to both lower risk of VR and higher probability of HBsAg loss.

Exosomes from Ub‑HBcAg‑overexpressing dendritic cells induce T‑lymphocyte differentiation and enhance cytotoxic T‑lymphocyte activity

Hepatitis B virus (HBV) infection is a major public health concern. The clearance of HBV may involve cytotoxic T-lymphocyte (CTL) activity and T helper type 1 reactions. Exosomes generated from dendritic cells (DCs) can induce immunological responses capable of eradicating viruses. However, exosomes loaded with antigens have not yet demonstrated therapeutic potential in HBV infection. Therefore, the present study aimed to investigate the antiviral effects of DC-derived exosomes (Dexs) loaded with ubiquitinated HBV core antigen (Dexs-Ub-HBcAg). Murine bone marrow-derived DCs were loaded with a recombinant lentivector encoding the ubiquitinated form of HBcAg. High-purity Dexs were generated using differential velocity centrifugation. Splenic T-lymphocytes were stimulated with Dexs-Ub-HBcAg and the specific T-cell-mediated immune responses were examined. Cytokine expression was analyzed using enzyme-linked immunosorbent assays. T-lymphocyte proliferation was detected using a Cell Counting Kit-8 assay and HBcAg-specific CTL activity was determined using a lactate dehydrogenase release assay. The results revealed that Dexs-Ub-HBcAg effectively stimulated T-cell proliferation and induced the activation of antigen-specific CTLs to exhibit HBcAg-specific CTL immune responses in vitro. These results suggest the potential of Dexs-Ub-HBcAg for development as a future therapeutic option for the elimination of HBV.

Action Mechanisms and Scientific Rationale of Using Nasal Vaccine (HeberNasvac) for the Treatment of Chronic Hepatitis B

Nasvac (HeberNasvac^®) is a novel therapeutic vaccine for chronic hepatitis B (CHB). This product is a formulation of the core (HBcAg) and surface (HBsAg) antigens of the hepatitis B virus (HBV), administered by nasal and subcutaneous routes, in a distinctive schedule of immunizations. In the present review article, we discuss the action mechanisms of HeberNasvac, considering the immunological properties of the product and their antigens. Specifically, we discuss the capacity of HBcAg to activate different pathways of innate immunity and the signal transduction after a multi-TLR agonist effect, and we review the results of recent clinical trials and in vitro studies. Aimed at understanding the clinical results of Nasvac and other therapeutic vaccines under development, we discuss the rationale of administering a therapeutic vaccine through the nasal route and also the current alternatives to combine therapeutic vaccines and antivirals (NUCs). We also disclose potential applications of this product in novel fields of immunotherapy.

Model to predict on-treatment restoration of functional HBV-specific CD8+ cell response foresees off-treatment HBV control in eAg-negative chronic hepatitis B

BACKGROUND

Hepatitis B virus (HBV)-specific CD8⁺ cell response restoration during nucleos(t)ide analogue (NUC) treatment could lead to off-treatment HBV control in e-antigen-negative chronic hepatitis B (CHBe(-)).

AIM

To predict this response with variables involved in T-cell exhaustion for use as a treatment stopping tool.

METHODS

In NUC-treated CHBe(-) patients, we considered a functional response in cases with HBV-specific CD8⁺ cells against core and polymerase HBV epitopes able to proliferate and secrete type I cytokines after antigen encounter. We performed a logistic regression model (LRM) to predict the likelihood of developing this response, based on patient age (subrogate of infection length), HBsAg level, NUC therapy starting point and duration (antigenic pressure). We discontinued treatment and assessed HBV DNA dynamics, HBsAg decline and loss during off-treatment follow-up according to LRM likelihood.

RESULTS

We developed an LRM that predicted the presence of a proliferative type I cytokine-secreting CD8⁺ cell response, which correlated positively with treatment duration and negatively with treatment initiation after the age of 40 years and with age adjusted by HBsAg level. We observed a positive correlation between LRM probability and intensity of proliferation, number of epitopes with the functional proliferating response and type I cytokine secretion level. Off-treatment, HBsAg loss, HBsAg decline >50% and HBV control were more frequent in the group with >90% LRM probability.

CONCLUSIONS

Short-term low-level antigen exposure and early long-term NUC treatment influence the restoration of a functional HBV-specific CD8⁺ cell response. Based on these predictors, a high likelihood of detecting this response at treatment withdrawal is associated with off-treatment HBV control and HBsAg decline and loss.

Prospects for the Global Elimination of Hepatitis B

Chronic hepatitis B virus (HBV) infection is the leading cause of liver cirrhosis and hepatocellular carcinoma, estimated to be globally responsible for ∼800,000 deaths annually. Although effective vaccines are available to prevent new HBV infection, treatment of existing chronic hepatitis B (CHB) is limited, as the current standard-of-care antiviral drugs can only suppress viral replication without achieving cure. In 2016, the World Health Organization called for the elimination of viral hepatitis as a global public health threat by 2030. The United States and other nations are working to meet this ambitious goal by developing strategies to cure CHB, as well as prevent HBV transmission. This review considers recent research progress in understanding HBV pathobiology and development of therapeutics for the cure of CHB, which is necessary for elimination of hepatitis B by 2030.

Therapeutic vaccination for treatment of chronic hepatitis B

Chronic hepatitis B infection remains a serious global health threat, contributing to a large number of deaths through liver cirrhosis and hepatocellular carcinoma. Current treatment does not eradicate disease, and therefore new treatments are urgently needed. In acute hepatitis B virus (HBV) a strong immune response is necessary to clear the virus, but in chronic infection the immune response is weakened and dysfunctional. Therapeutic vaccination describes the process of inoculating individuals with a non‐infective form of viral antigen with the aim of inducing or boosting existing HBV‐specific immune responses, resulting in sustained control of HBV infection. In this review we outline the rationale for therapeutic vaccination in chronic HBV infection, discuss previous and ongoing trials of novel HBV therapeutic vaccine candidates and outline strategies to improve vaccine efficacy going forward.

Combined viral quasispecies diversity and hepatitis B core-related antigen predict off-nucleos(t)ide analog durability in HBeAg-negative patients

BACKGROUND

Viral quasispecies dynamics between pre- and post-nucleos(t)ide analog (NA) therapy remains unclear.

AIM

This study aimed to investigate the HBV quasispecies evolution and its relationship with durability of off-therapy responses in HBeAg-negative chronic hepatitis B (CHB) patients who stopped NA therapy.

METHODS

Fifty-four HBeAg-negative CHB patients who stopped NAs, including 19 virological controllers (VC) who maintained serum HBV DNA < 2000 IU/mL beyond 1-year off-therapy, and 35 virological relapsers (VR) experiencing virological relapse within 1-year off-therapy were recruited. Viral quasispecies was analyzed by deep sequencing. Hepatitis B core-related antigen (HBcrAg) and HBsAg were also measured.

RESULTS

VC had significantly higher baseline viral quasispecies diversity of the precore/core gene, measured by nucleotide diversity, than VR. Low baseline viral nucleotide diversity (< 0.01) and high HBcrAg (≧ 2.0 KU/mL), but not HBsAg, at end of treatment (EOT) were significantly associated with higher risk of 1-year virological relapse (hazard ratio [HR] 6.09 and 3.31, respectively). Combination of low baseline viral nucleotide diversity and high HBcrAg at EOT could identify patients at high risk (HR 15.82). Further analysis of the evolution of HBV whole genome showed that HBV nucleotide diversity negatively correlated with serum HBV DNA levels. Notably, the viral quasispecies diversity between pre- and post-NA treatment remained relatively unchanged.

CONCLUSION

Higher baseline HBV quasispecies diversity associates with more durable off-therapy viral suppression in HBeAg-negative CHB patients. Combination of baseline viral nucleotide diversity and HBcrAg at EOT can identify patients at high risk for virological relapse after stopping NAs.

Pharmacotherapy options for managing hepatitis B in children

INTRODUCTION

To eliminate viral hepatitis by 2030, the World Health Organization (WHO) launched the first global health sector strategy on viral hepatitis, with particular focus given to hepatitis B and C in 2016. To achieve the reduction of mortality in children, it is indispensable to know which children should be treated and how to treat them.

AREA COVERED

In this article, the authors review the antiviral treatment of children with chronic hepatitis B virus (HBV) infection including antivirals available for children with chronic HBV infection.

EXPERT OPINION

The approvals of nucleos(t)ide analogues (NAs) and pegylated interferon (PEG-IFN) for children have lowered a hurdle to the initiation of antiviral treatment in children. The international guidelines use nearly the same criteria of antiviral treatment for children with chronic HBV infection, but the WHO guidelines provide a cautious stance on the antiviral treatment of children. Not only PEG-IFN but also NAs with a high genetic barrier to drug resistance should be the first-line treatment for children. In settings with limited medical resources, NAs can be the first-line treatment for children. Although the concept of an 'immune-tolerant phase' is challenged, evidence is not sufficient to recommend the treatment of HBeAg-positive immune-tolerant children.

Multiple Roles for Hepatitis B and C Viruses and the Host in the Development of Hepatocellular Carcinoma

Chronic hepatitis B and C viral infections are major risk factors for hepatocellular carcinoma (HCC) in the United States and worldwide. Direct and indirect mechanisms of viral infection lead to the development of HCC. Chronic viral infection leads to inflammation and liver damage, culminating in cirrhosis, the penultimate step in the progression toward HCC. Host, viral, and environmental factors likely interact to promote oncogenesis. Clinical considerations include recommendations for screening for HCC in persons at risk, treatment with antivirals, and an emerging role for immunotherapy in HCC. We pose unanswered questions regarding HCC susceptibility and pathogenesis in the setting of chronic hepatitis B and C.

Reversal of Immunity After Clearance of Chronic HCV Infection-All Reset?

Chronic viral infections cause deterioration of our immune system. However, since persistent infections rarely can be eliminated, the reinvigoration capacity of an exhausted immune system has remained largely elusive. Chronic hepatitis C virus (HCV) infection can since some years be effectively cured with novel direct acting antiviral agents. Thus, it is now possible to study reversal of immunity in patients that are cured from a long-lasting chronic infection. We here highlight recent developments in the analysis of various immune cell populations during and after clearance of HCV infection. Surprisingly, whereas reinvigoration of certain immune traits clearly can be seen, many features of immune exhaustion persist over time after viral elimination. Thus, a long-term chronic insult might result in irreversible damage to our immune system. This will be important to consider in therapeutic vaccination efforts against chronic infection and in the development of immunotherapy based strategies against cancer.

Hepatitis B virus persistence and reactivation

Hepatitis B virus (HBV) infection causes chronic hepatitis and has long term complications. Individuals ever infected with HBV are at risk of viral reactivation under certain circumstances. This review summarizes studies on HBV persistence and reactivation with a focus on the definitions and mechanisms. Emphasis is placed on the interplay between HBV replication and host immunity as this interplay determines the patterns of persistence following viral acquisition. Chronic infections exhibit as overt persistence when a defective immune response fails to control the viral replication. The HBV genome persists despite an immune response in the form of covalently closed circular DNA (cccDNA) and integrated DNA, rendering an occult state of viral persistence in individuals whose infection appears to have been resolved. We have described HBV reactivation that occurs because of changes in the virus or the immune system. This review aims to raise the awareness of HBV reactivation and to understand how HBV persists, and discusses the risks of HBV reactivation in a variety of clinical settings.

HBVsvp-Pulsed Dendritic Cell Immunotherapy Induces Th1 Polarization and Hepatitis B Virus-Specific Cytotoxic T Lymphocytes Production

Background

In chronic hepatitis B virus (CHB) patients, both dendritic cells (DCs) and T cells are functionally impaired and consequently the HBV-specific cellular immune responses are downregulated. The present study aims to investigate whether monocyte-derived DC (MoDCs)-pulsed-HBV subviral particles (HBVsvp) can polarize Th1 cells to induce HBV-specific cytotoxic T-lymphocytes (CTL) responses in CHB patients.

Methods and Materials

To this end, the human hepatoma HepG2.2.15 cell line was used to produce HBVsvp as a culturing system, and HBVsvp were concentrated for highly virus titer using the polyethylene glycol protocol. Peripheral blood mononuclear cells (PBMCs), collected from CHB patients and healthy donors, were differentiated into MoDCs and T cells. PBMCs-derived MoDCs were first pulsed with HBVsvp and then cultured with PBMCs-derived T cells. MoDCs and/or T subsets cells were identified for phenotypic activation by FACS analysis. The cytokine secretion of IL-4, IL-12, and IFN-γ in the culture supernatants was detected.

Results

The MoDCs were restored for their activation upon pulsing with HBVsvp in vitro, as identified by significantly overexpression of both CD86 and HLA-DR, and overproduction of IL-4 and IL-12. Furthermore, MoDCs-pulsed-HBVsvp induced Th1 frequencies and activated HBV-specific CTL to produce significantly highest amount of IFN-γ. Enhanced HBV-specific CTL led to strong cytolytic capacity against HepG2.2.15.

Conclusion

Overall, our data suggest that in vitro activation of MoDCs with HBVsvp overcomes the functionally impaired DCs and T cells in CHB patients offering a promising tool for therapeutic or vaccine-based approaches against HBV.

Optimized ex vivo stimulation identifies multi-functional HBV-specific T cells in a majority of chronic hepatitis B patients

High antigen burden during chronic hepatitis B (CHB) results in a low frequency HBV-specific T cell response with restricted functionality. However, this observation is based on limited data because low T cell frequencies have hindered effective ex vivo analysis. We adapted the ELISpot assay to overcome this obstacle to measure ex vivo T cell responses in CHB patients. We modified the key variables of cell number and the peptide pulsing method to improve ex vivo detection of HBV-specific T cells. We detected IFN-γ responses in 10/15 vaccinated controls and 20/30 CHB patients, averaging 195 and 84 SFUs/2 × 10⁶ PBMCs respectively. Multi-analyte FluoroSpots improved functional characterization of T cells. We detected IFN-γ responses in all tested vaccinated controls (n = 10) and CHB patients (n = 13). IL-2 responses were detectable in 9/10 controls and 10/13 patients. TNF-α displayed less sensitivity, detectable in only 7/10 controls and 7/13 patients. Antigen-specific analysis demonstrated that IFN-γ responses were dominated by polymerase and core, with weak responses to envelope and X. IL-2 responses were found in 3/5 patients and equally directed towards polymerase and core. While their ex vivo frequency is extremely low, a fraction of HBV-specific T cells are detectable and display multi-functionality ex vivo.

Mechanisms of HBV immune evasion

The concept of immune evasion is a longstanding topic of debate during chronic Hepatitis B Virus infection. The 292 million individuals chronically infected by HBV are clear evidence that the virus avoids elimination by the immune system. The exact mechanisms of immune evasion remain undefined and are distinct, but likely interconnected, between innate and adaptive immunity. There is a significant body of evidence that supports peripheral tolerance and exhaustion of adaptive immunity but our understanding of the role that central tolerance plays is still developing. Innate immunity instructs the adaptive immune response and subversion of its functionality will impact both T and B cell responses. However, literature around the interaction of HBV with innate immunity is inconsistent, with reports suggesting that HBV avoids innate recognition, suppresses innate recognition, or activates innate immunity. This complexity has led to confusion and controversy. This review will discuss the mechanisms of central and peripheral tolerance/exhaustion of adaptive immunity in the context of chronic HBV infection. We also cover the interaction of HBV with cells of the innate immune system and propose concepts for the heterogeneity of responses in chronically infected patients.

Trends in chronic hepatitis B treatment-related research from 1973 to 2018: a bibliometric and visual analysis

OBJECTIVE

Chronic hepatitis B (CHB) is a worldwide disease and the most common cause of liver cancer. This study aimed to identify specific areas of research activity concerning CHB treatment between 1973 and 2018 and to aid in identifying new areas for future development.

METHODS

The literature was searched from the GoPubMed and Web of Science databases using terms related to CHB treatment, analyzed with bibliometric methods and visualized using VOSviewer.

RESULTS

A total of 9486 and 5883 papers were collected from PubMed and Web of science, respectively. The studies focused on two clusters of topics: antiviral therapy for CHB and progressive diseases, and drug resistance. Studies related to antiviral drugs concentrated on lamivudine (n = 788), entecavir (n = 390), and adefovir dipivoxil (n = 376). Studies addressing conditions developing from CHB highlighted hepatocellular carcinoma (n = 403) and cirrhosis (n = 223). China (n = 1978) contributed the most publications. The 10 most quantitatively prolific organizations were in France. All 20 of the most cited papers investigated antiviral treatments for CHB or CHB-associated cirrhosis.

CONCLUSIONS

Research on CHB treatment over the past 45 years has concentrated on antiviral therapy, CHB-associated progressive conditions, drug resistance and immunization. Although work on CHB treatment has made considerable progress, new approaches must be explored.

Checkpoint Inhibitors and Therapeutic Vaccines for the Treatment of Chronic HBV Infection

Treatment of chronic hepatitis B virus (HBV) infection is highly effective in suppressing viral replication, but complete cure is rarely achieved. In recent years, substantial progress has been made in the development of immunotherapy to treat cancer. Applying these therapies to improve the management of chronic HBV infection is now being attempted, and has become an area of active research. Immunotherapy with vaccines and checkpoint inhibitors can boost T cell functions in vitro, and therefore may be used to reinvigorate the impaired HBV-specific T cell response. However, whether these approaches will suffice and restore antiviral T cell immunity to induce long-term HBV control remains an open question. Recent efforts have begun to describe the phenotype and function of HBV-specific T cells on the single epitope level. An improved understanding of differing T cell specificities and their contribution to HBV control will be instrumental for advancement of the field. In this review, we outline correlates of successful versus inadequate T cell responses to HBV, and discuss the rationale behind therapeutic vaccines and checkpoint inhibitors for the treatment of chronic HBV infection.

The effects of nucleoside/nucleotide analogues on host immune cells: the baseline for future immune therapy for HBV?

HBV is a non-cytopathic virus and the progression of liver fibrosis is attributed to the host immune response. Complete suppression of viral replication using nucleotide or nucleoside analogues (NUCs) can prevent most complications related to chronic HBV infection. Unfortunately, antiviral treatment has to be administered lifelong to the majority of patients as HBV persists in the hepatocytes. However, although NUCs are very frequently administered in clinical practice, their effects on vital parts of the host immune response to HBV are not well established. In this review we summarize the currently available data gathered from longitudinal studies that investigated treatment-associated alterations of HBV-specific CD4⁺ and CD8⁺ T-cells, regulatory T-cells and natural killer (NK) cells. These observations are important, as they can guide the design of studies that investigate the efficacy of new immune therapeutic agents. Novel experimental compounds will likely be added to ongoing NUC treatment, which leads to a functional cure in only a small minority of patients.

Toward a Functional Cure for Hepatitis B: The Rationale and Challenges for Therapeutic Targeting of the B Cell Immune Response

The central role of the cellular immune response in the control and clearance of the hepatitis B virus (HBV) infection has been well-established. The contribution of humoral immunity, including B cell and antibody responses against HBV, has been investigated for a long time but has attracted increasing attention again in recent years. The anti-HBs antibody was first recognized as a marker of protective immunity after the acute resolution of the HBV infection (or vaccination) and is now defined as a biomarker for the functional cure of chronic hepatitis B (CHB). In this way, therapies targeting HBV-specific B cells and the induction of an anti-HBs antibody response are essential elements of a rational strategy to terminate chronic HBV infection. However, a high load of HBsAg in the blood, which has been proposed to induce antigen-specific immune tolerance, represents a major obstacle to curing CHB. Long-term antiviral treatment by nucleoside analogs, by targeting viral translation by siRNA, by inhibiting HBsAg release via nucleic acid polymers, or by neutralizing HBsAg via specific antibodies could potentially reduce the HBsAg load in CHB patients. A combined strategy including a reduction of the HBsAg load via the above treatments and the therapeutic targeting of B cells by vaccination may induce the appearance of anti-HBs antibodies and lead to a functional cure of CHB.

The impact of currently licensed therapies on viral and immune responses in chronic hepatitis B: Considerations for future novel therapeutics

Despite the availability of a preventative vaccine, chronic hepatitis B (CHB) remains a global healthcare challenge with the risk of disease progression due to cirrhosis and hepatocellular carcinoma. Although current treatment strategies, interferon and nucleos(t)ide analogues have contributed to reducing morbidity and mortality related to CHB, these therapies are limited in providing functional cure. The treatment paradigm in CHB is rapidly evolving with a number of new agents in the developmental pipeline. However, until novel agents with functional cure capability are available in the clinical setting, there is a pressing need to optimize currently licensed therapies. Here, we discuss current agents used alone and/or in combination strategies along with the impact of these therapies on viral and immune responses. Novel treatment strategies are outlined, and the potential role of current therapies in the employment of pipeline agents is discussed.

Insights From Antiviral Therapy Into Immune Responses to Hepatitis B and C Virus Infection

There are 257 million persons worldwide with chronic hepatitis B virus (HBV) infection, a leading causes of liver cancer. Almost all adults with acute HBV infection have a rapid immune response to the virus, resulting in life-long immunity, but there is no cure for individuals with chronic HBV infection, which they acquire during early life. The mechanisms that drive the progression of HBV through distinct clinical phases to end-stage liver disease are poorly understood. Likewise, it is not clear whether and how immune responses can be modulated to allow control and/or clearance of intrahepatic HBV DNA. We review the innate and adaptive immune responses to acute and chronic HBV infections and responses to antiviral therapy. Comparisons with hepatitis C virus infection provide insights into the reversibility of innate inflammatory responses and the potential for successful therapy to recover virus-specific memory immune responses.

Viral hepatitis, inflammation, and cancer: A lesson for autoimmunity

In the present review, we analyzed the various overlapping and non-mutually exclusive mechanisms that intersect and form complex and highly flexible immunological networks allowing the defense against liver infections and tumors. Liver immunity results from the combination of the skills of systemic and local immune system(s) to sense and recognize pathogen or tumor antigens, to sensitize a wide range of innate and adaptive immune cells, and to clear the "invaders", through the establishment of a transient liver immunopathology state undergoing resolution/control of infections or tumors, and memory development. Then, a special emphasis is placed on discussing about the capacity of the immune system(s) to develop a state of chronic low-level immunopathology adapting through the intervention of simultaneous immunoregulatory mechanisms, when the liver is infected by highly mutable viruses (e.g., hepatitis B or C viruses [HBV or HCV]) capable to escape from the immune recognition. The establishment of chronic inflammation represents an advantage for the species survival, because it guarantees the long-term survival of human hosts despite the virus persistence. However, chronic inflammation, in the long run, can evolve towards severe consequences (decompensated cirrhosis and hepatocellular carcinoma) in some individuals, finding requiring the impelling need of discovering new therapeutic anti-viral and immunostimulatory agents addressed, in combination, to fight especially HBV that, in contrast to HCV, lacks antivirals capable to eradicate the virus. Finally, we discussed the concept proposing that the divergent immunoregulatory mechanisms that develop in persisting infections or tumors, on the one hand, and autoimmunity, on the other hand, are the mirror image of each other, whose understanding is also relevant for preparing novel immunotherapeutic approaches in autoimmune diseases.

Immunization with lentiviral vector‑modified dendritic cells encoding ubiquitinated hepatitis B core antigen promotes Th1 differentiation and antiviral immunity by enhancing p38 MAPK and JNK activation in HBV transgenic mice

Hepatitis B virus (HBV) infection is a global public health problem. T helper (Th)1‑associated cytokines are involved in HBV clearance during acute and persistent infection. In our previous study, it was demonstrated that lentiviral vectors encoding ubiquitinated hepatitis B core antigen (LV‑Ub‑HBcAg) effectively transduced dendritic cells (DCs) to induce maturation, which promoted T cell polarization to Th1 and generated HBcAg‑specific cytotoxic T lymphocytes (CTLs) ex vivo. In the present study, HBV transgenic mice were immunized with LV‑Ub‑HBcAg‑transduced DCs and HBcAg‑specific immune responses were evaluated. Cytokine expression was analyzed by ELISA. T lymphocyte proliferation was detected with a Cell Counting Kit‑8 assay and HBcAg‑specific CTL activity was determined using a lactate dehydrogenase release assay. The expression levels of p38‑mitogen‑activated protein kinase (p38‑MAPK), phosphorylated (p)‑p38MAPK, c‑Jun N‑terminal kinase (JNK) and p‑JNK were detected by western blot analysis. The results demonstrated that LV‑Ub‑HBcAg‑transduced DCs significantly increased the Th1/Th2 cytokine ratio, and effectively reduced the levels of serum hepatitis B surface antigen (HBsAg), HBV DNA, and liver HBsAg and HBcAg. Furthermore, the LV‑Ub‑HBcAg‑transduced DCs upregulated the expression of p‑P38‑MAPK and p‑JNK in T lymphocytes. In conclusion, the present study indicated that LV‑Ub‑HBcAg‑transduced DCs generated predominant Th1 responses and enhanced CTL activity in HBV transgenic mice. Activation of the P38‑MAPK/JNK signaling pathway may be involved in this induction.

Pegylated interferon-based sequential therapy for treatment of HBeAg reactive pediatric chronic hepatitis B-First study in children

BACKGROUND

Our aim was to evaluate the efficacy and safety of sequential therapy using pegylated interferon (Peg-IFN) and nucleos(t)ide analogue (NA) for treatment of children in immunoactive (IA) and immunotolerant (IT) phases of chronic hepatitis B.

METHODS

It was a prospective observational study where those willing for sequential therapy were allocated to group 1 (sequential therapy) and others to group 2 (standard therapy). Sequential therapy included 8 weeks of NA followed by 44 weeks of combination of NA and Peg-IFN. In group 2, IA children received NA monotherapy, and IT children received no therapy. HBe seroconversion, HBs seroconversion, and loss of HBV DNA were the major outcome measures.

RESULTS

A total of 61 children (36 IA and 25 IT) were included in the analysis. Among the IA children, 17 received sequential therapy and 19 received standard therapy; whereas, among the IT children, 12 received sequential therapy and 13 did not receive any therapy. In IA phase, sequential therapy led to higher HBe seroconversion (64.7% vs. 21.05%, p = 0.017) and higher virological clearance (94.12% vs. 52.63%, p = 0.008). In IT children, there was no benefit of treatment with sequential therapy over observation alone. Baseline ALT > 100 IU/L predicted response to therapy with 100% sensitivity, 89.5% specificity, and LR⁺ of 9.52.

CONCLUSION

Sequential therapy leads to higher HBe seroconversion and virological response in children in IA phase. Children with baseline ALT > 100 IU/mL are more likely to respond to sequential therapy. There appears to be no role of sequential therapy in children in IT phase.

Immune responses of human T lymphocytes to novel hepatitis B virus-derived peptides

Background & aims

Many individuals are infected with hepatitis B virus (HBV) worldwide, and this virus is commonly controlled by treatments with interferon (IFN)-alpha and nucleoside analogues (NA). However, the complete elimination of HBV by these treatments is difficult and, thus, the development of new treatments is needed. Host immune responses are closely involved in the elimination of HBV, suggesting the usefulness of immunotherapy. In the present study, we attempted to identify novel cytotoxic T-lymphocyte (CTL) epitopes that are useful for immunotherapy against HBV.

Methods

CTL epitopes were predicted using computer software. Immune responses to each peptide were evaluated by IFN-γ ELISPOT and cytotoxic assays. The relationships between the immune responses to these newly identified CTL epitopes and the clinical backgrounds of patients and administration of NA were analyzed. Peptides were administered to mice as vaccines and peptide-specific T-cell induction was measured in vivo.

Results

Positive reactions to 10 synthesized peptides were detected in 3 or more patients using the IFN-γ ELISPOT assay, and concentration-dependent cytotoxicity against 2 of these peptides was observed in the cytotoxic assay. Some peptides that correlated with serum ALT, HBsAg, and HBV core-related antigen (HBcrAg) levels were identified. Immune reactions against some peptides were enhanced by the administration of NA. Regarding their effects as a vaccine, peptide-specific T-cells were induced by four peptides in vivo.

Conclusions

Novel HBV epitopes that correlated with HBsAg and HBcrAg levels were identified. These newly identified epitopes may be useful in the analysis of immune responses to HBV and development of immunotherapy against HBV.

Is it possible to stop nucleos(t)ide analogue treatment in chronic hepatitis B patients?

Chronic hepatitis B (CHB) remains a challenging global health problem, with nearly one million related deaths per year. Nucleos(t)ide analogue (NA) treatment suppresses viral replication but does not provide complete cure of the hepatitis B virus (HBV) infection. The accepted endpoint for therapy is the loss of hepatitis B surface antigen (HBsAg), but this is hardly ever achieved. Therefore, indefinite treatment is usually required. Many different studies have evaluated NA therapy discontinuation after several years of NA treatment and before HBsAg loss. The results have indicated that the majority of patients can remain off therapy, with some even reaching HBsAg seroconversion. Fortunately, this strategy has proved to be safe, but it is essential to consider the risk of liver damage and other comorbidities and to ensure a close follow-up of the candidates before considering this strategy. Unanswered questions remain, namely in which patients could this strategy be effective and what is the optimal time point at which to perform it. To solve this enigma, we should keep in mind that the outcome will ultimately depend on the equilibrium between HBV and the host’s immune system. Viral parameters that have been described as good predictors of response in HBeAg(+) cases, have proven useless in HBeAg(-) ones. Since antiviral immunity plays an essential role in the control of HBV infection, we sought to review and explain potential immunological biomarkers to predict safe NA discontinuation in both groups.

Reduced therapeutic effect of antiviral drugs in patients with hepatitis B virus reactivation after hematopoietic stem cell transplantation

AIM

Patients with resolved hepatitis B virus (HBV) infection following hematopoietic stem cell transplantation (HSCT) are potentially at high risk of HBV reactivation. Although antiviral drug therapy is recommended when HBV DNA reappears in the serum, drug efficacy after HBV reactivation remains unclear.

METHODS

Host immune response against HBV was investigated by immunological analyses at 12 months after entecavir (ETV) treatment in six HSCT-treated and five non-HSCT-treated patients with HBV reactivation, and 18 patients with chronic hepatitis B (CHB). Peripheral HBV-specific CD8⁺ T cells were analyzed for total numbers by flow cytometry and tetramer staining, as was intracellular γ-interferon (IFN-γ) production and CD107a expression in response to HBV peptides. Interleukin-10 (IL-10)-expressing CD19⁺ B-cell count and serum inflammatory cytokine levels were also analyzed.

RESULTS

Serum HBV DNA was detectable in HSCT-treated patients with HBV reactivation at 12 months compared with other groups, indicating insufficient ETV efficacy against HBV. The HBV-specific CD8⁺ T-cell counts in HSCT-treated patients with HBV reactivation were significantly lower compared with those in non-HSCT patients. Additionally, IFN-γ production and CD107a expression by CD8⁺ T cells after incubation with HBV peptides was significantly reduced in HSCT-treated compared with CHB patients at 12 months after ETV treatment. Conversely, HSCT-treated patient serum IL-10 levels were significantly elevated compared with those in non-HSCT patients. Finally, IL-10-producing CD19⁺ B-cell counts were increased in HSCT-treated compared with CHB patients.

CONCLUSION

After HBV reactivation, ETV efficacy was impaired in HSCT-treated patients as evidenced by low HBV-specific CD8⁺ T-cell counts and high B-cell IL-10 production.

Clinical impact of the early alanine amininotransferase flare during tenofovir monotherapy in treatment-naïve patients with chronic hepatitis B

BACKGROUND/AIMS

Little is known about the effect of early flares on response during first-line tenofovir disoproxil fumarate (TDF) treatment for chronic hepatitis B (CHB). The aim of this study was to investigate the incidence and outcome of early alanine aminotransferase (ALT) flare in treatment-naive patients with CHB during long-term TDF monotherapy.

METHODS

One hundred eighty-one treatment-naive CHB patients were treated with a 300-mg once-daily dose of TDF for more than 12 weeks. Virological markers of hepatitis B virus (HBV) and biochemical data were measured at baseline and every 4-12 weeks during the therapy. The proportion of patients with undetectable HBV DNA level (< 100 copies/mL) was noted.

RESULTS

The median age was 48.3 years and 122 patients (67.4%) were men. Hepatitis B envelope antigen (HBeAg) was positive in 101 patients (55.8%). No patient had cirrhosis. The median follow-up duration was 45 weeks (12-155 weeks). ALT flare (>5 × upper limit of the normal range) occurred in seven patients (3%) without viral breakthrough within the first 8 weeks after the start of TDF monotherapy. Among them, six patients were HBeAg-positive and one patient was HBeAg-negative. All cases of early ALT flares resolved within 4 weeks and virologic response was observed in all patients without interruption or discontinuation of treatment.

CONCLUSIONS

Continuous TDF monotherapy was effective and safe in treatment-naive patients with CHB who experienced early ALT flares followed by a decrease in HBV DNA level.

HIV Suppression Restores the Lung Mucosal CD4+ T-Cell Viral Immune Response and Resolves CD8+ T-Cell Alveolitis in Patients at Risk for HIV-Associated Chronic Obstructive Pulmonary Disease

BACKGROUND

Lung CD4⁺ T-cell depletion and dysfunction, CD8⁺ T-cell alveolitis, smoking, and poor control of human immunodeficiency virus (HIV) are features of HIV-associated chronic obstructive pulmonary disease (COPD), but these changes have not been evaluated in smokers at risk for COPD. We evaluated the impact of viral suppression following initiation of antiretroviral therapy (ART) on HIV-specific immunity and the balance of the CD4⁺ T-cell to CD8⁺ T-cell ratio in the lung.

METHODS

Using flow cytometry, we assessed the T-cell immune response in lung and blood specimens obtained from 12 actively smoking HIV-positive patients before ART initiation and after ART-associated viral suppression.

RESULTS

HIV suppression resulted in enhanced lung and systemic HIV-specific CD4⁺ T-cell immune responses without significant changes in CD8⁺ T-cell responses. We observed an increase in lung ratios of CD4⁺ T cells to CD8⁺ T cells and CD4⁺ T-cell frequencies, decreased CD8⁺ T-cell numbers, and resolution of CD8⁺ T-cell alveolitis after ART in 9 of 12 individuals. Viral suppression reduced Fas receptor and programmed death 1 expression in lung CD4⁺ T cells, correlating with enhanced effector function and reduced susceptibility to apoptosis. HIV suppression rescued peripheral but not lung HIV-specific CD4⁺ T-cell proliferation, resulting in augmented effector multifunction.

DISCUSSION

Together, our results demonstrate that HIV suppression restores lung mucosal HIV-specific CD4⁺ T-cell multifunctional immunity and balance in the ratio of CD4⁺ T cells to CD8⁺ T cells, often resolving CD8⁺ T-cell alveolitis in active smokers. Peripheral expansion and redistribution of CD4⁺ T cells and increased resistance to apoptosis are 2 mechanisms contributing to immunologic improvement following viral suppression in patients at risk for HIV-associated COPD.

Chronic hepatitis B: immune pathogenesis and emerging immunotherapeutics

Hepatitis B virus (HBV) evades, subverts, activates and regulates host immune components, thereby impacting its natural history and disease pathogenesis. Recent advances in our understanding of immune interactions in chronic viral infection and tumor therapy are applicable to chronic hepatitis B (CHB). With recent successes of tumor immunotherapy, there is a renewed interest in exploring immunotherapeutics in achieving sustained and functional cure of chronic hepatitis B. In this review, we discuss aspects of host innate and adaptive immune regulatory and pathogenic responses relevant for HBV infection. We also highlight several immune modulatory approaches in clinical development to treat CHB.

Dynamic of Immune Response induced in Hepatitis B Surface Antigen-transgenic Mice Immunized with a Novel Therapeutic Formulation

The development of therapeutic vaccines against chronic hepatitis B requires the capacity of the formulation to subvert a tolerated immune response as well as the evaluation of histopathological damage resulting from the treatment. In the present study, the dynamicity of induced immune response to hepatitis B surface antigen (HBsAg) was evaluated in transgenic mice that constitutively express the HBsAg gene (HBsAg-tg mice). After immunization with a vaccine candidate containing both surface (HBsAg) and core (HBcAg) antigens of hepatitis B virus (HBV), the effect of vaccination on clearance of circulating HBsAg and the potential histological alterations were examined. Transgenic (tg) and non-transgenic (Ntg) mice were immunized by intranasal (IN) and subcutaneous (SC) routes simultaneously. A control group received phosphate-buffered saline (PBS) by IN route and aluminum by SC route. Positive responses, at both humoral and cellular levels, were obtained after five immunizations in HBsAg-tg mice. Such responses were delayed and of lower intensity in tg mice, compared to vaccinated Ntg mice. Serum IgG response was characterized by a similar IgG subclass pattern. Even when HBsAg-specific CD8⁺ T cell responses were clearly detectable by gamma-interferon ELISPOT assay, histopathological alterations were not detected in any organ, including the liver and kidneys. Our study demonstrated, that it is possible to subvert the immune tolerance against HBsAg in tg mice, opening a window for new studies to optimize the schedule, dose, and formulation to improve the immune response to the therapeutic vaccine candidate. These results can be considered a safety proof to support clinical developments for the formulation under study.

How to cite this article

Freyre FM, Blanco A, Trujillo H, Hernández D, García D, Alba JS, Lopez M, Merino N, Lobaina Y, Aguilar JC. Dynamic of Immune Response induced in Hepatitis B Surface Antigen-transgenic Mice Immunized with a Novel Therapeutic Formulation. Euroasian J Hepato-Gastroenterol 2016;6(1):25-30.

Hepatitis B Virus--Specific and Global T-Cell Dysfunction in Chronic Hepatitis B

BACKGROUND & AIMS

T cells play a critical role in viral infection. We examined whether T-cell effector and regulatory responses can define clinical stages of chronic hepatitis B (CHB).

METHODS

We enrolled 200 adults with CHB who participated in the National Institutes of Health-supported Hepatitis B Research Network from 2011 through 2013 and 20 uninfected individuals (controls). Peripheral blood lymphocytes from these subjects were analyzed for T-cell responses (proliferation and production of interferon gamma and interleukin 10) to overlapping hepatitis B virus (HBV) peptides (preS, S, preC, core, and reverse transcriptase), influenza matrix peptides, and lipopolysaccharide. T-cell expression of regulatory markers FOXP3, programmed death-1, and cytotoxic T lymphocyte-associated antigen-4 was examined by flow cytometry. Immune measures were compared with clinical parameters, including physician-defined immune-active, immune-tolerant, or inactive CHB phenotypes, in a blinded fashion.

RESULTS

Compared with controls, patients with CHB had weak T-cell proliferative, interferon gamma, and interleukin 10 responses to HBV, with increased frequency of circulating FOXP3(+)CD127(-) regulatory T cells and CD4(+) T-cell expression of programmed death-1 and cytotoxic T lymphocyte-associated antigen-4. T-cell measures did not clearly distinguish between clinical CHB phenotypes, although the HBV core-specific T-cell response was weaker in hepatitis B e antigen (HBeAg)(+) than HBeAg(-) patients (percent responders: 3% vs 23%; P = .00008). Although in vitro blockade of programmed death-1 or cytotoxic T lymphocyte-associated antigen-4 increased T-cell responses to HBV, the effect was weaker in HBeAg(+) than HBeAg(-) patients. Furthermore, T-cell responses to influenza and lipopolysaccharide were weaker in CHB patients than controls.

CONCLUSIONS

HBV persists with virus-specific and global T-cell dysfunction mediated by multiple regulatory mechanisms, including circulating HBeAg, but without distinct T-cell-based immune signatures for clinical phenotypes. These findings suggest additional T-cell-independent or regulatory mechanisms of CHB pathogenesis that warrant further investigation.

Immune-surveillance through exhausted effector T-cells

Pathogens such as the human immunodeficiency virus (HIV), the hepatitis B and C virus (HBV, HCV) and certain strains of the rodent lymphocytic choriomeningitis virus (LCMV) establish a state of persisting viral replication. This occurs besides strong adoptive immune responses and the induction of large numbers of activated pathogen-specific T-cells. The failure of the immune system to clear these viruses is typically attributed to a loss of effector T-cell function-a phenomenon referred to as T-cell exhaustion. Though largely accepted, this loss of function concept is being more and more challenged by comprehensive clinical and experimental observations which highlight that T-cells in chronic infections are more functional than previously considered. Here, we highlight examples that demonstrate that such T-cells mediate a profound form of immune-surveillance. We also briefly discuss the opportunities and limitations of employing 'exhausted' T-cells for therapeutic purposes.

Prospects and progress of DNA vaccines for treating hepatitis B

The hepatitis B virus (HBV) is a global cause of liver disease. The preventive HBV vaccine has effectively reduced the disease burden. However, an estimated 340 million chronic HBV cases are in need of treatment. Current standard therapy for chronic HBV blocks reverse transcription. As this therapy blocks viral maturation and not viral protein expression, any immune inhibition exerted by these proteins will remain throughout therapy. This may help to explain why these drugs rarely induce off-therapy responses. Albeit some restoration of immune function occurs during therapy, this is clearly insufficient to control replication. Central questions when considering therapeutic DNA vaccination as an addition to blocking virus production are as follows: what does one hope to achieve? What do we think is wrong and how can the vaccination correct this? We here discuss different scenarios with respect to the lack of success of tested DNA vaccines, and suggest strategies for improvement.

IL-12-Dependent Cytomegalovirus-Specific CD4+ T Cell Proliferation, T-bet Induction, and Effector Multifunction during Primary Infection Are Key Determinants for Early Immune Control

CMV remains an important opportunistic pathogen in solid organ and hematopoietic cell transplantation, particularly in lung transplant recipients (LTRs). LTRs mismatched for CMV (donor(+)/recipient(-); D(+)R(-)) are at high risk for active CMV infection and increased mortality; however, the immune correlates of viral control remain incompletely understood. We prospectively studied 27 D(+)R(-) LTRs during primary CMV infection to determine whether acute CD4(+) T cell parameters differentiated the capacity for viral control during early chronic infection. Unexpectedly, the T-box transcription factor, T-bet, was expressed at low levels in CD4(+) compared with CD8(+) T cells during acute primary infection. However, the capacity for in vitro CMV phosphoprotein 65-specific proliferation and CD4(+)T-bet(+) induction differentiated LTR controllers from early viremic relapsers, correlating with granzyme B loading and effector multifunction. Furthermore, impaired CMV-specific proliferative responses from relapsers, along with T-bet, and effector function could be significantly rescued, most effectively with phosphoprotein 65 Ag and combined exogenous IL-2 and IL-12. Acute CD4(+) T cell CMV-specific proliferative and effector responses were highly IL-12-dependent in blocking studies. In addition, we generated monocyte-derived dendritic cells using PBMC obtained during primary infection from relapsers and observed impaired monocyte-derived dendritic cell differentiation, a reduced capacity for IL-12 production, but increased IL-10 production compared with controls, suggesting an APC defect during acute CMV viremia. Taken together, these data show an important role for CMV-specific CD4(+) effector responses in differentiating the capacity of high-risk LTRs to establish durable immune control during early chronic infection and provide evidence for IL-12 as a key factor driving these responses.

Dendritic cell-based vaccination with lentiviral vectors encoding ubiquitinated hepatitis B core antigen enhances hepatitis B virus-specific immune responses in vivo

The activity of hepatitis B virus (HBV)-specific cytotoxic T lymphocytes (CTLs) plays a predominant role in the clearance of HBV. Dendritic cells (DCs) are key antigen-presenting cells and play an important role in the initiation of immune responses. We previously verified that lentiviral vector encoding ubiquitinated hepatitis B core antigen (LV-Ub-HBcAg) effectively transduced DCs to induce maturation, and the mature DCs efficiently induced T cell polarization to Th1 and generated HBcAg-specific CTLs ex vivo. In this study, HBV-specific immune responses of LV-Ub-HBcAg in BALB/c mice (H-2Kd) were evaluated. It was shown that direct injection of LV-Ub-HBcAg increased the production of cytokines IL-2 and IFN-γ, elicited strong antibody responses, and remarkably generated a high percentage of IFN-γ+CD8+ T cells with HBV-specific CTL responses in BALB/c mice. In addition, direct injection of LV-Ub-HBcAg induced potent anti-HBV immune responses, similar to those elicited by in vitro-transduced DCs. In conclusion, the DC-based therapeutic vaccine LV-Ub-HBcAg elicited specific antibody immune responses and induced robust specific CTL activity in vivo.

Advances in therapeutics for chronic hepatitis B

Chronic hepatitis B infection remains a major disease burden globally, and leads to high risk of hepatocellular carcinoma development. Current therapies of nucleot(s)ide analogues and interferon alpha treatment remain limited in their efficacy. Several key findings in the hepatitis B virus (HBV) life cycle have led to the development of novel antiviral drugs to inhibit viral replication and persistence. In addition, recent studies on HBV-specific innate and adaptive immune responses have advanced development of immunotherapy to restore immune mediated virus control in chronic hepatitis B patients. In this review, we discuss potential new therapeutic strategies targeting HBV or the host immune system that might lead to a sustained cure for chronic hepatitis B.

The Efficacy and Safety of Entecavir and Interferon Combination Therapy for Chronic Hepatitis B Virus Infection: A Meta-Analysis

The objective of this study was to evaluate the effectiveness and safety of entecavir (ETV) and interferon (IFN) combination therapy in the treatment of chronic hepatitis B (CHB) mono-infection via a meta-analysis of randomized controlled trials (RCTs). All eligible RCTs evaluating combination therapy for treating CHB were identified from nine electronic databases. A meta-analysis was performed in accordance with the Cochrane Systemic Review handbook. Eleven trials encompassing 1010 participants were included in this meta-analysis. It showed that at 12 and ≥ 96 weeks of therapy, the combination of ETV and IFN was not better than ETV in improving the undetectable HBV DNA (12 weeks: RR=1.12, 95% CI=0.88-1.42; ≥ 96 weeks: RR = 0.64, 95% CI=0.21-1.98, respectively) and HBeAg seroconversion rates (12 weeks: RR=1.35, 95% CI=0.60-3.04; ≥ 96 weeks: RR=1.36, 95% CI=0.75-2.64, respectively). But at 48 weeks of therapy and approximately 2 years of follow up, combination therapy was superior to ETV in improving the undetectable HBV DNA (48 weeks: RR=1.46, 95% CI=1.13-1.90; follow up: RR=2.20, 95% CI=1.26-3.81, respectively) and HBeAg seroconversion rates (48 weeks: RR=1.82, 95% CI=1.44-2.30; follow up: RR=1.92, 95% CI=1.19-3.11, respectively). When compared to IFN group, at 24 and 48 weeks of therapy, combination group showed a greater undetectable HBV DNA (24 weeks: RR=2.14, 95% CI=1.59-2.89; 48 weeks: RR=2.28, 95% CI=1.54-3.37, respectively) and ALT normalization rate (24 weeks: RR=1.56, 95% CI= 1.24-1.96; 48 weeks: RR=1.55, 95% CI = 1.16-2.07, respectively). At 48 weeks of therapy, combination group achieved a greater HBeAg seroconversion rate than IFN (48 weeks: RR=1.58, 95% CI=1.24-2.00). No significant differences were observed in the side effects of the three therapies. So we can conclude that ETV and IFN combination therapy is more effective than ETV or IFN mono-therapy in CHB treatment. ETV, IFN, and the combination of the two are safe in CHB treatment.

Vaccination with ubiquitin-hepatitis B core antigen-cytoplasmic transduction peptide enhances the hepatitis B virus-specific cytotoxic T-lymphocyte immune response and inhibits hepatitis B virus replication in transgenic mice

Chronic hepatitis B virus (HBV) infection is characterized by functionally impaired type 1 T-helper cell (Thl) immunity and poor HBV‑specific T‑cell responses. Ubiquitin (Ub), a highly conserved small regulatory protein, commonly serves as a signal for target proteins that are recognized and degraded in proteasomes. The rapid degradation of Ub‑mediated antigens results in efficient stimulation of cell‑mediated immune responses. Thus, the Ub‑HBV core antigen (HBcAg)‑cytoplasmic transduction peptide (CTP) fusion protein was designed for specific delivery of a foreign modified antigen to the cytoplasm of antigen‑presenting cells. HBV transgenic mice were used to determine whether Ub‑HBcAg‑CTP would restore HBV‑specific immune responses and anti‑viral immunity in these animals. The results demonstrated that synthesized Ub‑HBcAg‑CTP not only significantly increased the levels of interleukin‑2 and interferon (IFN)‑γ compared with those in the HBcAg‑CTP, IFN‑α, Ub‑HBcAg, HBcAg and phosphate‑buffered saline groups, but additionally induced the highest IFN‑γ+ CD8+ T‑cell numbers and HBV‑specific cytotoxic T lymphocyte (CTL) responses, indicating a strong immune response. In addition, enhancement of specific CTL activity provoked by the fusion protein reduced hepatitis B surface antigen (HBsAg) and HBV DNA serum levels and diminished the expression of HBsAg and HBcAg in liver tissue of HBV transgenic mice, suggesting that there was a therapeutic effect. In conclusion, the present study provided evidence that Ub‑HBcAg‑CTP activated the Th1‑dependent immunity, triggered functional T cell responses and subsequently inhibited viral replication in HBV transgenic mice. These observations suggested that the fusion protein may represent an innovative and promising candidate for active immunotherapy during chronic and persistent HBV.

Long-Term Outcome of Sequential Therapy with Lamivudine Followed by Interferon-β in Nucleoside-Naive, Hepatitis B e-Antigen-Positive Patients with Chronic Hepatitis B Virus Genotype C Infection

It is unclear whether the combination of a nucleos(t)ide analog and interferon (IFN) is superior to monotherapy for treating chronic hepatitis B. In this study, we report the long-term outcomes of sequential therapy using lamivudine followed by IFN-β. This study included 24 hepatitis B e-antigen (HBeAg)-positive patients with chronic hepatitis B virus (HBV) genotype C infection who were treated with lamivudine alone for 16-32 weeks, then with both IFN-β and lamivudine for 4 weeks, and finally with IFN-β alone for 20 weeks. All patients were followed up for 7.1±2.8 years post-treatment. The rate of response, defined as transaminase normalization, HBeAg loss, and HBV DNA <10(4) copies/mL, was 5/24 (21%) at 24 weeks post-treatment. The patients with short-term responses were younger than those with no response (P=0.039). More short-term responders had undetectable HBV DNA at the start of IFN-β compared with the nonresponders (P=0.0059). Subsequently, 4 of the 5 short-term responders remained free of the need for further drug treatment for 4.2±3.5 years post-treatment; more short-term responders remained drug free than did nonresponders (P=0.035). In conclusion, the rate of response to sequential therapy was limited in HBeAg-positive patients with chronic HBV genotype C infection at 24 weeks post-treatment. In the majority of the short-term responders, however, the response was sustainable in the long term.

Immunological aspects of antiviral therapy of chronic hepatitis B virus and hepatitis C virus infections

Hepatitis B virus (HBV) and hepatitis C virus (HCV) cause a large proportion of acute and chronic liver disease worldwide. Over the past decades many immunological studies defined host immune responses that mediate spontaneous clearance of acute HBV and HCV infection. However, host immune responses are also relevant in the context of treatment-induced clearance of chronic HBV and HCV infection. First, the pretreatment level of interferon-stimulated genes as well as genetic determinants of innate immune responses, such as single nucleotide polymorphisms near the IFNL3 gene, are strong predictors of the response to interferon-alpha (IFN-α)-based therapy. Second, IFN-α, which has been a mainstay of HBV and HCV therapy over decades, and ribavirin, which has also been included in interferon-free direct antiviral therapy for HCV, modulate host immune responses. Third, both IFN-α-based and IFN-α-free treatment regimens of HBV and HCV infection alter the short-term and long-term adaptive immune response against these viruses. Finally, treatment studies have not just improved the clinical outcomes, but also provided opportunities to study virus-host interaction. This review summarizes our current knowledge on how a patient's immune response affects the treatment outcome of HBV and HCV infection and how innate and adaptive immune responses themselves are altered by the different treatment regimens.

Enhanced immune response to hepatitis B vaccination through immunization with a Pre-S1/Pre-S2/S vaccine

Efficacy and safety of recombinant yeast-derived hepatitis B vaccines for prevention of hepatitis B have been demonstrated unequivocally worldwide as reflected in reduction in HBsAg carrier rates and hepatocellular carcinoma. A new generation of recombinant HBV vaccines expressed in mammalian cells containing Pre-S/S epitopes has been developed in several countries. Such vaccines are useful in special risk groups, i.e., in non-responders to conventional HBV vaccines including older adults, obese people, health care workers, patients with renal failure and on dialysis, transplant patients, patients with HIV as well as travelers on short notice to HBV endemic regions. The future of such vaccines depends on their enhanced immunogenicity and cost profile. Sci-B-Vac™ is a mammalian cell-derived recombinant Pre-S1/Pre-S2/S hepatitis B vaccine which has been shown to be highly immunogenic, inducing faster and higher seroprotection rates against HBV with higher anti-HBs levels at lower HBsAg doses as compared to conventional yeast-derived vaccines. Recently, it has been suggested that such Pre-S/S vaccines against HBV might be efficacious not only for prevention but also for intervention in persistent HBV infection. Data obtained in a recent clinical trial conducted in Vietnam in patients with chronic hepatitis B suggest that repeated monthly i.m. injections of the Sci-B-Vac™ co-administered with daily oral lamivudine treatment can suppress HBV replication and lead to anti-HBs seroconversion in ~50 % of treated patients. Optimization of protocols and efficacy of such an intervention, intended to bypass T cell exhaustion and immune tolerance to HBV remains to be explored.

HBV and the immune response

Hepatitis B virus (HBV) infection acquired in adult life is generally self-limited while chronic persistence of the virus is the prevalent outcome when infection is acquired perinatally. Both control of infection and liver cell injury are strictly dependent upon protective immune responses, because hepatocyte damage is the price that the host must pay to get rid of intracellular virus. Resolution of acute hepatitis B is associated with functionally efficient, multispecific antiviral T-cell responses which are preceded by a poor induction of intracellular innate responses at the early stages of infection. Persistent control of infection is provided by long-lasting protective memory, which is probably sustained by continuous stimulation of the immune system by trace amounts of virus which are never totally eliminated, persisting in an occult episomic form in the nucleus of liver cells even after recovery from acute infection. Chronic virus persistence is instead characterized by a lack of protective T-cell memory maturation and by an exhaustion of HBV-specific T-cell responses. Persistent exposure of T cells to high antigen loads is a key determinant of functional T-cell impairment but also other mechanisms can contribute to T-cell inhibition, including the tolerogenic effect of the liver environment. The degree of T-cell impairment is variable and its severity is related to the level of virus replication and antigen load. The antiviral T-cell function is more efficient in patients who can control infection either partially, such as inactive HBsAg carriers with low levels of virus replication, or completely, such as patients who achieve HBsAg loss either spontaneously or after antiviral therapy. Thus, understanding the features of the immune responses associated with control of infection is needed for the successful design of novel immune modulatory therapies based on the reconstitution of efficient antiviral responses in chronic HBV patients.

The kinetics of the hepatitis B surface antigen level after the initiation of antiretroviral therapy for hepatitis B virus and human immunodeficiency virus coinfected patients

BACKGROUND

Hepatic flares (HF), which reflect hepatitis B virus (HBV)-related immune reconstitution inflammatory syndrome (IRIS), frequently occur in patients with HBV and human immunodeficiency virus (HIV) coinfection after the start of antiretoroviral therapy (ART). The rate of hepatitis B envelope antigen (HBeAg) and hepatitis B surface antigen (HBsAg) loss is higher for patients with HF after the initiation of ART.

METHODS

We retrospectively examined the kinetics of the HBsAg and HBeAg levels of six HBV/HIV coinfected patients after the commencement of ART that included tenofovir. All were male and HBeAg positive.

RESULTS

Three patients developed HF after the initiation of ART. All subsequently lost HBeAg and one of them lost HBsAg after HF. None who did not experience HF lost HBeAg. The HBsAg and HBeAg levels remarkably decreased when HF occurred, but the decline of HBsAg was very slow in the periods before and after HF. The median decline of the HBsAg level at 48 weeks was 2.20 Log IU/mL for patients with HF, but only 1.00 Log IU/ml for patients without HF. Little decline was seen for either group in the median decline of the HBsAg level from 48 weeks to 96 weeks, 0.28 Log IU/mL in the HF group and 0.06 Log IU/mL in the non-HF group.

CONCLUSION

The immune reconstitution of a HBV/HIV coinfected patient plays an important role in the clearance of HBV. If HBsAg and HBeAg levels decrease rapidly when HF occurs, the hepatic flare would be due to HBV-related IRIS.

Functional aspects of intrahepatic hepatitis B virus-specific T cells induced by therapeutic DNA vaccination

Current therapies for the hepatitis B virus (HBV), a major cause of severe liver disease, suppress viral replication but replication rebounds if therapy is withdrawn. It is widely accepted that immune activation is needed to control replication off-therapy. To specifically activate T cells crossreactive between the hepatitis B core and e antigens (HBcAg/HBeAg) in chronically infected patients, we developed a therapeutic vaccine candidate. The vaccine encompass codon-optimized HBcAg and IL-12 expressing plasmids delivered using targeted high-pressure injection combined with in vivo electroporation. One dose of the vaccine primed a B-cell-independent polyfunctional T-cell response, in wild-type, and in HBeAg-transgenic mice with an impaired ability to respond to HBc/eAg. The response peaked at 2 weeks and contracted at week 6 after vaccination. Coadministration of IL-12 improved antibody levels, and T-cell expansion and functionality. The vaccine primed T cells that, 2 weeks after a single dose, cleared hepatocytes transiently expressing HBcAg in vaccinated wild-type and HBeAg-transgenic mice. However, 4 weeks later, these functional responses were lost. Booster doses after 8-12 weeks effectively restored function and expansion of the rapidly contracting T cells. Thus, this vaccine strategy primes functional HBcAg-specific T cells in a host with dysfunctional response to HBV.

T-bet:Eomes balance, effector function, and proliferation of cytomegalovirus-specific CD8+ T cells during primary infection differentiates the capacity for durable immune control

CMV remains an important opportunistic pathogen in solid organ transplantation, particularly in lung transplant recipients (LTRs). LTRs mismatched for CMV (donor+/recipient-; D+R-) are at high-risk for active CMV infection and increased mortality, however the immune correlates of viral control remain incompletely understood. We prospectively studied 23 D+R- LTRs during primary CMV infection to determine whether acute CD8(+) T cell parameters differentiated the capacity for viral control in early chronic infection. T-box transcription factors expression patterns of T-bet > Eomesodermin (Eomes) differentiated LTR controllers from viremic relapsers and reciprocally correlated with granzyme B loading, and CMV phosphoprotein 65 (pp65)-specific CD8(+)IFN-γ(+) and CD107a(+) frequencies. LTR relapsers demonstrated reduced CD8(+)Ki67(+) cells ex vivo and substantially impaired CD8(+)pp65-specific in vitro proliferative responses at 6 d, with concomitantly lower pp65-specific CD4(+)IL-2(+) frequencies, as compared with LTR controllers. However, CMV-specific in vitro proliferative responses could be significantly rescued, most effectively with pp65 Ag and exogenous IL-2, resulting in an increased T-bet:Eomes balance, and enhanced effector function. Using class I CMV tetramers, we observed similar frequencies between relapsers and controllers, although reduced T-bet:Eomes balance in tetramer(+) cells from relapsers, along with impaired CD8(+) effector responses to tetramer-peptide restimulation. Taken together, these data show impaired CMV-specific CD8(+) effector responses is not for complete lack of CMV-specific cells but rather underscores the importance of the T-bet:Eomes balance, with CMV-specific proliferation a key factor driving early T-bet expression and effector function in CD8(+) T cells during primary infection and differentiating the capacity of high-risk LTRs to establish immune control during early chronic infection.

The influences of antiviral therapy on T-cell function in adult patients with chronic hepatitis B

ABSTRACT 

T cells play an important role in the clearance of acute infection and control of hepatitis B virus (HBV) infection during the chronic phase. Chronic HBV is characterized by a weak and limited T-cell response. Several hypotheses, such as presence of Tregs or occurrence of T-cell exhaustion have been proposed to explain these observations. The two registered classes of anti-HBV drugs: pegylated-IFN-α (PEG-IFN-α) and nucleos(t)ide analogs (NUCs) have, next to their antiviral effect, also an immunomodulatory effect. Although NUCs have no direct immunomodulatory effects, they may indirectly positively affect the T-cell response through their viral suppressive action. In this review, effects of both PEG-IFN-α and NUC therapy will be discussed with regard to the cellular immune response against HBV.