The phenotype of hepatitis B virus-specific T cells differ in the liver and blood in chronic hepatitis B virus infection

Monocyte and Macrophage Functions in Oncogenic Viral Infections

Monocytes and macrophages are part of innate immunity and constitute the first line of defense against pathogens. Bone marrow-derived monocytes circulate in the bloodstream for one to three days and then typically migrate into tissues, where they differentiate into macrophages. Circulatory monocytes represent 5% of the nucleated cells in normal adult blood. Following differentiation, macrophages are distributed into various tissues and organs to take residence and maintain body homeostasis. Emerging evidence has highlighted the critical role of monocytes/macrophages in oncogenic viral infections, mainly their crucial functions in viral persistence and disease progression. These findings open opportunities to target innate immunity in the context of oncogenic viruses and to explore their potential as immunotherapies.

Evaluation of the Effect of CD70 Co-Expression on CD8 T Cell Response in Protein-Prime MVA-Boost Vaccination in Mice

Here, we investigate the potential of CD70 co-expression during viral vector boost vaccination to improve an antigen-specific T cell response. To determine the chance of activating antigen-specific T cells by CD70, we used the HBV core antigen as a model antigen in a heterologous protein-prime, Modified Vaccinia virus Ankara (MVA) boost vaccination scheme. Both the HBV core and a CD70 expression cassette were co-expressed upon delivery by an MVA vector under the same promoter linked by a P2A site. To compare immunogenicity with and without CD70 co-expression, HBV-naïve, C57BL/6 (wt) mice and HBV-transgenic mice were prime-vaccinated using recombinant HBV core antigen followed by the MVA vector boost. Co-expression of CD70 increased the number of vaccine-induced HBV core-specific CD8 T cells by >2-fold and improved their effector functions in HBV-naïve mice. In vaccinated HBV1.3tg mice, the number and functionality of HBV core-specific CD8 T cells was slightly increased upon CD70 co-expression in low-viremic, but not in high-viremic animals. CD70 co-expression did not impact liver damage as indicated by ALT levels in the serum, but increased the number of vaccine-induced, proliferative T cell clusters in the liver. Overall, this study indicates that orchestrated co-expression of CD70 and a vaccine antigen may be an interesting and safe means of enhancing antigen-specific CD8 T cell responses using vector-based vaccines, although in our study it was not sufficient to break immune tolerance.

Hepatitis B Virus Flares After Nucleot(s)ide Analogue Cessation Are Associated With Activation of Toll-Like Receptor Signaling Pathways

BACKGROUND

We evaluated the patterns of peripheral Toll-like receptor (TLR) signaling activity and the expression of TLRs and natural killer (NK) cell activation in a cohort of patients experiencing severe hepatitis flares after stopping nucleot(s)ide analogues (NAs) therapy.

METHODS

Samples were collected longitudinally from patients with chronic hepatitis B who were enrolled in a prospective study of NA discontinuation. Patients experiencing hepatitis flares were compared with patients with normal alanine aminotransferase. Peripheral blood mononuclear cells (PBMCs) were stimulated with TLR ligands and cytokine secretion in the cell culture supernatant measured. Expression of TLR2/4, NKG2D, NKp46, and triggering receptor expressed on myeloid cells 1 (TREM-1) on monocytes, NK, and NK-T cells was measured.

RESULTS

Seventeen patients with severe reactivation hepatitis flares were compared to 12 nonflare patients. Hepatitis flares were associated with increased activity of TLR2-8 and TLR9 signaling in PBMCs at the time of peak flare compared to baseline. Hepatitis flares were also associated with (1) upregulation of TLR2 and (2) TREM-1 receptor expression on NK. There were no differences at baseline between flare patients and nonflare patients.

CONCLUSIONS

Hepatitis flares off NA therapy have a significant innate inflammatory response with upregulation of TLR signaling on peripheral monocytes and TLR2 and TREM-1 expression on NK cells. This implicates the innate immune system in the immunopathogenesis of hepatitis B flares.

Advances in Immunotherapy for Hepatitis B

Hepatitis B virus (HBV) is a hepatotropic virus with the potential to cause chronic infection, and it is one of the common causes of liver disease worldwide. Chronic HBV infection leads to liver cirrhosis and, ultimately, hepatocellular carcinoma (HCC). The persistence of covalently closed circular DNA (cccDNA) and the impaired immune response in patients with chronic hepatitis B (CHB) has been studied over the past few decades. Despite advances in the etiology of HBV and the development of potent virus-suppressing regimens, a cure for HBV has not been found. Both the innate and adaptive branches of immunity contribute to viral eradication. However, immune exhaustion and evasion have been demonstrated during CHB infection, although our understanding of the mechanism is still evolving. Recently, the successful use of an antiviral drug for hepatitis C has greatly encouraged the search for a cure for hepatitis B, which likely requires an approach focused on improving the antiviral immune response. In this review, we discuss our current knowledge of the immunopathogenic mechanisms and immunobiology of HBV infection. In addition, we touch upon why the existing therapeutic approaches may not achieve the goal of a functional cure. We also propose how combinations of new drugs, and especially novel immunotherapies, contribute to HBV clearance.

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.

Highly activated TRAIL+ CD56bright NK cells are associated with the liver damage in HBV-LC patients

BACKGROUND

Chronic hepatitis B-related liver cirrhosis(HBV-LC)is the most common cirrhosis in China, which is characterized as liver damage and high mortality. We aim to investigate the characteristics of TRAIL+NK cells in patients with HBV-LC and their relationship with liver damage in patients with HBV-LC.

METHODS

Thirty cases each of chronic hepatitis B (CHB), HBV-related compensated liver cirrhosis (HBV-CLC) and HBV-related decompensated liver cirrhosis (HBV-DLC) patients were recruited in this study. Thirty age-and sex-matched healthy individuals were recruited as healthy controls (HCs). NK cell phenotypes were determined using flow cytometry. Serum chemokine concentrations were ascertained using the CBA Flex set. Cell apoptosis was analyzed using the Annexin V-PE/7-AAD apoptosis Kit.

RESULTS

CD56bright NK cells increased, but CD56dim NK cells reduced in HBV-LC patients. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was mainly expressed on CD56bright NK cells. As the degree of liver damage increased, the frequency and activation of total TRAIL+NK cells and TRAIL+NK cell subsets continued to increase, especially in the HBV-LC patients. Furthermore, the difference in frequency and activation of total TRAIL+NK cells between the HBV-CLC and HBV-DLC groups was mainly due to the highly activation and increase of TRAIL+CD56bright NK cells. With the increasing degree of liver damage, CXCR3-associated chemokines (including CXCL9, CXCL10 and CXCL11) were constantly increased, particularly in the HBV-DLC group. The expression of CXCR3 on CD56bright NK cells was almost 100 % in all enrolled cohorts. CXCR3-associated chemokines were negatively correlated with liver function and positively correlated with fibrosis degree. TRAIL+CD56bright NK cells were negatively correlated with liver function, and positively correlated with fibrosis degree and CXCR3-associated chemokines. The apoptosis of K562 cells and hepatocytes was suppressed partially by the TRAIL-neutralizing antibodies.

CONCLUSIONS

The increase of CXCR3-related chemokines (including CXCL9, CXCL10 and CXCL11) might be related to the migration of TRAIL+ CD56bright NK cells to the liver. Highly activated TRAIL+ CD56bright NK cells were associated with the liver damage in HBV-LC patients. These findings may provide new perspectives and theoretical basis for future immunotherapy of HBV-LC patients.

Abnormal IL-10 levels were related to alanine aminotransferase abnormalities during postpartum in HBeAg positive women with chronic hepatitis B

Alanine transaminase (ALT) abnormalities are common in chronic hepatitis B (CHB) carriers during postpartum period. Disturbances in cytokines are considered to be associated with hepatitis Flares. There are limited data on cytokines changes in HBeAg positive patients with ALT abnormalities.This is an observational study. Pregnant patients with hepatitis B e-antigen (HBeAg) positive were enrolled from January 2014 to September 2018. Patients were assigned into three groups based on ALT levels in postpartum 6 to 8 weeks: ALT in normal range, ALT in 1 to 2-fold upper limits of normal (ULN) and ALT >2-fold ULN. Serum cytokines, ratios of regulatory T cells, and the concentration of cortisol were collected and compared among the three groups.Of the 135 mothers enrolled, 80.7% (109/135) completed the postpartum 6-week study. 13.8% (15/109) patients had postpartum ALT higher than 2ULN, 27.5% (30/109) patients had ALT in 1 to 2ULN and 58.7% (64/109) patients had ALT in normal range. Compared to control group, patients with ALT >2ULN had a higher IL-10 level (P < .05). No differences of IL-10 levels were found in the comparison of other inter comparison among three groups. No differences were found in the levels of other collected serum cytokines, cortisol, and regulatory T cells among three groups. On multivariate analysis, abnormal IL-10 level was independent risk factor for postpartum ALT elevating >2ULN. At the same time, the incidence of postpartum ALT elevated >2ULN were higher in patients with abnormal elevation IL-10 level than in patients with normal IL-10 level (14/68 vs 1/41, P = .008).CHB patients with postpartum ALT abnormalities show higher IL-10 level and postpartum ALT abnormalities were mainly occurred in patients with abnormal IL-10 level. IL-10 may be an underlying predictor and treatment target of hepatitis B, and further studies are needed.

Immune function of plasmacytoid dendritic cells, natural killer cells, and their crosstalk in HBV infection

Chronic hepatitis B virus infection is a major health problem, with over 245 million chronic carriers worldwide. This persistent infection is thought to be associated with inefficient innate and adaptive immune responses. Natural killer cells (NK cells) and plasmacytoid dendritic cells (pDCs) are the major innate immune cells which respond to viral infection at the early phase and are considered major components of the antiviral immune response. In this review, we summarize recent findings regarding the role of NK cells, pDCs, and their cross-talk in HBV infection and its chronicity. Although the data regarding the biological function of pDCs and NK cells in HBV infection is still controversial, many studies show that in chronic HBV infection, the cytotoxicity of NK cells is retained, while their capacity to secrete cytokines is strongly impaired. In addition, interferon-α production by pDCs is impaired during chronic HBV infection, and the virus interferes with pDC-NK cell interaction.

Programmed cell death-1 3'-untranslated region polymorphism is associated with spontaneous clearance of hepatitis B virus infection

Hepatitis B virus (HBV)-specific CD8+ T cells play an important role in the clearance of HBV infection. Programmed cell death-1 (PD-1), an immunosuppressive molecule that regulates T-cell activation and peripheral immune tolerance, is increasingly shown to influence the outcome of HBV infection. rs10204525, a single-nucleotide polymorphism in the 3'-untranslated region (3'-UTR) of PD-1, has been associated with susceptibility and disease progression of chronic HBV infection in far-eastern patients. The aim of our study was to assess the impact of rs10204525 variation on HBV infection in Moroccan patients. A total of 236 patients with chronic HBV infection and 134 individuals with spontaneous HBV resolution were genotyped using a Taqman assay. In addition, PD-1 mRNA expression in peripheral blood nuclear cells was determined by quantitative reverse-transcription polymerase chain reaction. We found that the AA genotype is protective (odds ratio, 0.43; 95% confidence interval, 0.19 to 0.97; P = 0.038) against HBV infection. Interestingly, PD-1 messenger RNA (mRNA) expression analysis has revealed that chronic HBV carriers with GG and GA displayed higher levels of PD-1 mRNA compared with corresponding genotypes in resolved subjects (P = 0.031 and 0.014, respectively). Our data suggest that Mediterranean HBV-infected patients carrying PD-1 GG and GA genotypes at rs10204525 have high PD-1 mRNA expression and may be more prone to installation of chronicity.

Patient-shared TCRβ-CDR3 clonotypes correlate with favorable prognosis in chronic hepatitis B

The presence of shared T-cell clonotypes was found in several different diseases, but its relationship with the progression of disease remains unclear. By sequencing the complementary determining region 3 of T-cell receptor (TCR) β chains from the purified antigen-experienced CD8⁺ T cells, we characterized the T-cell repertoire in a prospective cohort study among 75 patients with chronic hepatitis B in China, as well as a healthy control and a validation cohort. We found that most T-cell clones from patients harbored the "patient-specific" TCR sequences. However, "patient-shared" TCR clonotypes were also widely found, which correlated with the favorable turnover of disease. Interestingly, the frequency of the "patient-shared" clonotypes can serve as a biomarker for favorable prognosis. Based on the clonotypes in those patients with favorable outcomes, we created a database including several clusters of protective anti-HBV CD8⁺ T-cell clonotypes that might be a reasonable target for therapeutic vaccine development or adoptive cell transfer therapy. These findings were validated in an additional independent cohort of patients. These results suggest that the "patient-shared" TCR clonotypes may serve as a valuable prognostic tool in the treatment of chronic hepatitis B and possibly other chronic viral diseases.

Hepatitis B Virus Adaptation to the CD8+ T Cell Response: Consequences for Host and Pathogen

Chronic viral hepatitis infections are a major public health concern, with an estimated 290 million individuals infected with hepatitis B virus (HBV) globally. This virus has been a passenger in human populations for >30,000 years, and remains highly prevalent in some settings. In order for this endemic pathogen to persist, viral adaptation to host immune responses is pre-requisite. Here, we focus on the interplay between HBV infection and the CD8+ T cell response. We present the evidence that CD8+ T cells play an important role in control of chronic HBV infection and that the selective pressure imposed on HBV through evasion of these immune responses can potentially influence viral diversity, chronicity, and the outcome of infection, and highlight where there are gaps in current knowledge. Understanding the nature and mechanisms of HBV evolution and persistence could shed light on differential disease outcomes, including cirrhosis and hepatocellular carcinoma, and help reach the goal of global HBV elimination by guiding the design of new strategies, including vaccines and therapeutics.

Liver sampling: a vital window into HBV pathogenesis on the path to functional cure

In order to optimally refine the multiple emerging drug targets for hepatitis B virus (HBV), it is vital to evaluate virological and immunological changes at the site of infection. Traditionally liver biopsy has been the mainstay of HBV disease assessment, but with the emergence of non-invasive markers of liver fibrosis, there has been a move away from tissue sampling. Here we argue that liver biopsy remains an important tool, not only for the clinical assessment of HBV but also for research progress and evaluation of novel agents. The importance of liver sampling has been underscored by recent findings of specialised subsets of tissue-resident immune subsets capable of efficient pathogen surveillance, compartmentalised in the liver and not sampled in the blood. Importantly, the assessment of virological parameters, such as cccDNA quantitation, also requires access to liver tissue. We discuss strategies to maximise information obtained from the site of infection and disease pathology. Fine needle aspirates of the liver may allow longitudinal sampling of the local virus/host landscape. The careful utilisation of liver tissue and aspirates in conjunction with blood will provide critical information in the assessment of new therapeutics for the functional cure of HBV.

Immune checkpoint blockade in infectious diseases

The upregulation of immune checkpoint molecules, such as programmed cell death protein 1 (PD1) and cytotoxic T lymphocyte antigen 4 (CTLA4), on immune cells occurs during acute infections, such as malaria, as well as during chronic persistent viral infections, including HIV and hepatitis B virus. These pathways are important for preventing immune-driven pathology but can also limit immune-mediated clearance of the infection. The recent success of immune checkpoint blockade in cancer therapy suggests that targeting these pathways would also be effective for preventing and treating a range of infectious diseases. Here, we review our current understanding of immune checkpoint pathways in the pathogenesis of infectious diseases and discuss the potential for therapeutically targeting these pathways in this setting.

Dynamic Perturbations of CD4 and CD8 T Cell Receptor Repertoires in Chronic Hepatitis B Patients upon Oral Antiviral Therapy

Long-term treatment with nucleos(t)ide analogs (NUCs) can improve the antiviral T cell response in chronic hepatitis B (CHB) patients. Whether and to what extent the T cell response is improved by NUCs in the early stage leading to hepatitis B e antigen (HBeAg) seroconversion remain to be clarified. A total of 22 CHB patients undergoing 2-year telbivudine-based therapy were enrolled, including 10 exhibiting a complete response (CR) and 12 exhibiting a non-complete response (NCR) according to HBeAg seroconversion at week 52. Peripheral CD4⁺ and CD8⁺ T cells were sorted at baseline, weeks 12, and 24. The T cell receptor β chain (TCRβ) complementarity-determining region 3 was analyzed by unbiased high-throughput sequencing. Compared with NCR group, patients in CR group had a much lower percentage of persistent clonotypes (P < 0.001) but remarkably higher percentages of new and expanded clonotypes (P < 0.05) between any two time points for both CD4 and CD8 subsets. The CD4 T cells exhibited a stronger response than CD8 population in the patients. The number of new and expanded clonotypes was inversely associated with the decline of viral antigen. In conclusion, NUC-based therapy induces a broad and vigorous T cell response with rapid decline of antigenemia during the early stage of treatment. A broad T cell expansion is crucial for HBeAg seroconversion. Our findings suggest that the potent suppression of hepatitis B virus replication by NUC monotherapy complemented with additional immunomodulatory strategies may increase the likelihood of a functional cure for CHB in the future.

Hepatic expansion of virus-specific CD8+BTLA+ T cells with regulatory properties in chronic hepatitis B virus infection

Similar to programmed death-1 (PD-1), B and T lymphocyte attenuator (BTLA) is a co-inhibitory molecule of the CD28 family. PD-1 is involved in T cell exhaustion during chronic viral infection. However, the role of BTLA in virus-specific T cells is poorly defined. Here we investigated the expression and function of BTLA in T cells from patients with chronic hepatitis B virus (HBV) infection. The phenotype of peripheral and intrahepatic HBV-specific T cells from 43 patients with chronic HBV infection was assessed by flow cytometry. Functional evaluation was analyzed by T cell expansion and cytokine secretion after different treatments. In chronic HBV patients, a subset of inefficient interferon-γ producing antigen-specific CD8⁺ T cells recruited to the liver expressed high BTLA levels. The BTLA⁺ HBV-specific CD8⁺ T cell suppressive function was antigen-specific, at least in the induction phase, because they were only activated by a pool of HBV peptides but not with a pool of unrelated peptides. Suppression of T cell responses was restored by a BTLA signaling blockade and neutralizing IL-10, indicating that BTLA signaling-mediated IL-10 secretion plays a key role in suppression. This study provides important evidence that there is a subset of liver infiltrated virus-specific CD8⁺BTLA⁺ regulatory T cells in patients with chronic HBV infection. This subset of cells plays a pivotal role in controlling hepatic effector CD8⁺ T cell responses through BTLA signaling mediated regulatory factor IL-10 production.

Increased CD86 but Not CD80 and PD-L1 Expression on Liver CD68+ Cells during Chronic HBV Infection

BACKGROUND

The failure to establish potent anti-HBV T cell responses suggests the absence of an effective innate immune activation. Kupffer cells and liver-infiltrating monocytes/macrophages have an essential role in establishing anti-HBV responses. These cells express the costimulatory molecules CD80 and CD86. CD80 expression on antigen-presenting cells (APCs) induces Th1 cell differentiation, whereas CD86 expression drives the differentiation towards a Th2 profile. The relative expression of CD80, CD86 and PD-L1 on APCs, regulates T cell activation. Few studies investigated CD80 and CD86 expression on KCs and infiltrating monocytes/macrophages in HBV-infected liver and knowledge about the expression of PD-L1 on these cells is controversial. The expression of these molecules together in CD68+ cells has not been explored in HBV-infected livers.

METHODS

Double staining immunohistochemistry was applied to liver biopsies of HBV-infected and control donors to explore CD80, CD86 and PD-L1 expression in the lobular and portal areas.

RESULTS

Chronic HBV infection was associated with increased CD68+CD86+ cell count and percentage in the lobular areas, and no changes in the count and percentage of CD68+CD80+ and CD68+PD-L1+ cells, compared to the control group. While CD68+CD80+ cell count in portal areas correlated with the fibrosis score, CD68+CD80+ cell percentage in lobular areas correlated with the inflammation grade.

CONCLUSION

The upregulation of CD86 but not CD80 and PD-L1 on CD68+ cells in HBV-infected livers, suggests that these cells do not support the induction of potent Th1. Moreover, the expression of CD80 on CD68+ cells correlates with liver inflammation and fibrosis.

IL-10-producing regulatory B-cells suppressed effector T-cells but enhanced regulatory T-cells in chronic HBV infection

Non-specific immune responses to antigens have been demonstrated as being enhanced during chronic hepatitis B virus (HBV) infection. Here, we evaluated the role of interleukin-10 (IL-10)-producing regulatory B-cells (Bregs) in the pathogenesis of HBV-related liver fibrosis (HBV-LF) and assessed their immunoregulatory effects. Sixty-seven patients diagnosed with chronic hepatitis B (CHB) were enrolled in this study. Numbers and frequencies of peripheral B-cells (memory CD19(+)CD24(hi)CD27(+) cells, immature/transitional CD19(+)CD24(hi)CD38(hi) cells, mature CD19(+)CD24(int)CD38(int) cells) were tested and analysed. Flow cytometry-sorted CD4(+)T cells were cultured with autologous Bregs to elucidate the effects of Bregs on CD4(+)T cells, including effector T and regulatory T-cells (Tregs). The potential immunoregulatory mechanism of Bregs was also investigated. The numbers of total B-cells and Bregs were enriched in CHB patients. The frequency of Bregs was negatively correlated with elevated alanine aminotransferase (ALT) and histological inflammation grades (G), but positively correlated with advanced histological fibrosis stages (S) and enhanced HBV replication. The phenotype of Bregs was predominantly characterized as CD19(+)CD24(hi)CD38(hi) In co-culture with Bregs, CD4(+)CD25(-)T cells from CHB patients produced less interferon-γ (IFN-γ) and IL-17 but more IL-4 than CD4(+)CD25(-)T cells alone, whereas their conversions into Tregs and IL-10(+)T cells were enhanced. In addition, Breg depletion in CHB samples dramatically decreased Treg numbers and expression of cytotoxic T-lymphocyte associated antigen-4 (CTLA-4), IL-10 and transforming growth factor-β (TGF-β). Moreover, the observed regulatory effect was partly dependent on IL-10 release and cell-to-cell contact. Elevated Bregs can suppress effector T but enhance Treg functions, which might influence immune tolerance in chronic HBV infection.

The role of innate immunity in the immunopathology and treatment of HBV infection

In this review we give a brief update on sensors recently determined to be capable of detecting HBV, and examine how the virus represses the induction of pro-inflammatory cytokines like type I interferons. We overview cellular components of innate immunity that are present at high frequencies in the liver, and discuss their roles in HBV control and/or pathogenesis. We argue that many innate effectors have adaptive-like features or can exert specific effects on HBV through immunoregulation of T cells. Finally we consider current and possible future strategies to manipulate innate immunity as novel approaches towards a functional cure for HBV.

Therapeutic vaccines in HBV: lessons from HCV

Currently, millions of people infected with hepatitis B virus (HBV) are committed to decades of treatment with anti-viral therapy to control viral replication. However, new tools for immunotherapy that include both viral vectors and molecular checkpoint inhibitors are now available. This has led to a resurgence of interest in new strategies to develop immunotherapeutic strategies with the aim of inducing HBeAg seroconversion—an end-point that has been associated with a decrease in the rates of disease progression. Ultimately, a true cure will involve the elimination of covalently closed circular DNA which presents a greater challenge for immunotherapy. In this manuscript, I describe the development of immunotherapeutic strategies for HBV that are approaching or currently in clinical studies, and draw on observations of T cell function in natural infection supported by recent animal studies that may lead to additional rational vaccine strategies using checkpoint inhibitors. I also draw on our recent experience in developing potent vaccines for HCV prophylaxis based on simian adenoviral and MVA vectors used in prime–boost strategies in both healthy volunteers and HCV infected patients. I have shown that the induction of T cell immune responses is markedly attenuated when administered to people with persistent HCV viremia. These studies and recently published animal studies using the woodchuck model suggest that potent vaccines based on DNA or adenoviral vectored vaccination represent a rational way forward. However, combining these with drugs to suppress viral replication, alongside checkpoint inhibitors may be required to induce long-term immune control.

CD8+ T cell responses specific for hepatitis B virus core protein in patients with chronic hepatitis B virus infection

BACKGROUND

Chronic hepatitis B virus (HBV) infection includes a set of heterogeneous clinical patterns, and core-protein-specific T cell response is important for virus control and disease progression, yet is not well elucidated.

OBJECTIVES

To analyze the phenotypic and functional profiles of HBV-core-protein-specific CD8+ T cells in different clinical patterns of chronic HBV infection.

STUDY DESIGN

A total of 46 HBV patients were recruited and classified according to their clinical status. CD8+ T cell responses in different patterns of chronic HBV infections were tested with flow cytometry using overlapping 15-mer peptides covering HBV core protein. Meanwhile, the CCR7/CD27 phenotypes of these CD8+ T cells were also determined.

RESULTS

Frequencies of gamma interferon (IFN-γ) positive CD8+ T cells in inactive HBV surface antigen (HBsAg) carriers in response to the core protein peptide pools were generally stronger than those of chronic HBV carriers and resolved individuals, especially with regards to peptide pool C13-C24. Moreover, phenotypic studies further highlighted the group of CD8+ CCR7-CD27+ T memory cells, which showed significantly higher levels of IFN-γ secretion in inactive HBsAg carriers than those in chronic hepatitis B patients, chronic HBV carriers and resolved individuals.

CONCLUSIONS

Core-protein-specific T cell response plays an important role in chronic HBV infection. Inactive HBsAg carriers showed a much stronger core-protein-specific cytotoxic T cell response than other types of chronically infected patients. CD8+ CCR7-CD27+ T memory lymphocytes may be crucial in the immune pathogenesis of chronic HBV infection.

TCRγδ(+)CD4(-)CD8(-) T cells suppress the CD8(+) T-cell response to hepatitis B virus peptides, and are associated with viral control in chronic hepatitis B

The immune mechanisms underlying failure to achieve hepatitis B e antigen (HBeAg) seroconversion associated with viral control in chronic hepatitis B (CHB) remain unclear. Here we investigated the role of CD4(-)CD8(-) T (double-negative T; DNT) cells including TCRαβ(+) DNT (αβ DNT) and TCRγδ(+) DNT (γδ DNT) cells. Frequencies of circulating DNT cell subsets were measured by flow cytometry in a retrospective cohort of 51 telbivudine-treated HBeAg-positive CHB patients, 25 immune tolerant carriers (IT), 33 inactive carriers (IC), and 37 healthy controls (HC). We found that γδ DNT cell frequencies did not significantly change during treatment, being lower at baseline (P = 0.019) in patients with HBeAg seroconversion after 52 weeks of antiviral therapy (n = 20) than in those without (n = 31), and higher in the total CHB and IT than IC and HC groups (P<0.001). αβ DNT cell frequencies were similar for all groups. In vitro, γδ DNT cells suppressed HBV core peptide-stimulated interferon-γ and tumor necrosis factor-α production in TCRαβ(+)CD8(+) T cells, which may require cell-cell contact, and could be partially reversed by anti-NKG2A. These findings suggest that γδ DNT cells limit CD8(+) T cell response to HBV, and may impede HBeAg seroconversion in CHB.

Modeling and simulating dynamics of complete- and poor-response chronic hepatitis B chinese patients for adefovir and traditional chinese medicine plus adefovir therapy

ChiCTR-TRC-11001263 study was the first large-scale double-blind randomized placebo-controlled traditional Chinese medicines (TCMs) and adefovir (ADV) antihepatitis B virus (HBV) infection trial in the world. A total of 560 hepatitis B e antigen- (HBeAg-) positive Chinese patients with chronical HBV were randomly classified, in 1 : 1 ratio, into two groups: experimental group (EXG) receiving TCMs + ADV and controlled group (CTG) receiving ADV + TCM-placebo treatment for 48 weeks. This paper introduces two models to model and simulate the evolutions of dynamics for the complete-response patients and the poor-response patients in EXG and CTG, respectively. The stimulated mean HBV DNA and alanine aminotransferase (ALT) levels were close to the patients' experimental data. Analysis and simulations suggest that the activated patients' immune functions by TCMs + ADV may not only clear infected hepatocytes, but also clear HBV, which made the complete-response patients' mean serum HBV DNA levels in EXG reduce rapidly 12 weeks' earlier than the ones in CTG. One can assume that both the TCMs and ADV have the function of preventing complete-response patients' infected hepatocytes from being injured by cytotoxic T lymphocytes (CTLs); the patients' activated immune cells may also block HBV replications.

Hepatitis B virus-specific T-cell responses during IFN administration in a small cohort of chronic hepatitis B patients under nucleos(t)ide analogue treatment

The effect of pegylated interferon-α (IFN) add-on therapy on HBV-specific T-cell responses was evaluated in 12 patients with stable, undetectable hepatitis B virus (HBV) load under nucleos(t)ide analogue therapy. Peripheral blood mononuclear cells were isolated at week 0, 4, 8, 12, 24 and 48 of IFN add-on therapy. Quantity and quality of circulating HBV S- and core-specific CD4 and CD8 T cells were analysed ex vivo by flow cytometry. HBV S- and core-specific CD4 T-cell numbers modestly increased within 8 weeks of IFN administration (P = 0.0391 and P = 0.0195), whereas HBV-specific CD8 T cells in general showed only minor changes under IFN add-on therapy. Functionality of HBV-specific CD4 but not CD8 T cells positively correlated with serum transaminase activity. In addition, we observed an increase in CD4 T cells producing tumour necrosis factor-α (TNFα) without antigen restimulation (P = 0.0039), which correlated with elevated transaminases. During IFN add-on therapy, two patients developed an anti-HBs seroconversion, only one of whom showed a relevant increase in HBV-specific T cells. In conclusion, IFN add-on therapy of chronic hepatitis B increased HBV-specific T-cell responses and affected a previously unrecognized TNFα-monofunctional CD4 T-cell population. Although the observed T-cell responses did not correlate with HBsAg seroconversion, we expect additional insights into the immunopathogenesis of hepatitis B, following the characterization of the newly identified TNF α-monofunctional T-cell population.

HIV and co-infections

Despite significant reductions in morbidity and mortality secondary to availability of effective combination anti-retroviral therapy (cART), human immunodeficiency virus (HIV) infection still accounts for 1.5 million deaths annually. The majority of deaths occur in sub-Saharan Africa where rates of opportunistic co-infections are disproportionately high. In this review, we discuss the immunopathogenesis of five common infections that cause significant morbidity in HIV-infected patients globally. These include co-infection with Mycobacterium tuberculosis, Cryptococcus neoformans, hepatitis B virus, hepatitis C virus, and Plasmodium falciparum. Specifically, we review the natural history of each co-infection in the setting of HIV, the specific immune defects induced by HIV, the effects of cART on the immune response to the co-infection, the pathogenesis of immune restoration disease (IRD) associated with each infection, and advances in the areas of prevention of each co-infection via vaccination. Finally, we discuss the opportunities and gaps in knowledge for future research.

Natural killer cells are characterized by the concomitantly increased interferon-γ and cytotoxicity in acute resolved hepatitis B patients

Natural killer (NK) cells are abundant in the liver and have been implicated in inducing hepatocellular damage in patients with chronic hepatitis B virus (HBV) infection. However, the role of NK cells in acute HBV infection remains to be elucidated. We comprehensively characterized NK cells and investigated their roles in HBV clearance and liver pathology in 19 chronic hepatitis B (CHB) patients and 21 acute hepatitis B (AHB) patients as well as 16 healthy subjects. It was found that NKp46⁺ NK cells were enriched in the livers of AHB and CHB patients. We further found that peripheral NK cells from AHB patients expressed higher levels of activation receptors and lower levels of inhibitory receptors than those from CHB patients and HC subjects, thus displaying the increased cytolytic activity and interferon-γ production. NK cell activation levels were also correlated positively with serum alanine aminotransferase levels and negatively with plasma HBV DNA levels in AHB patients, which is further confirmed by the longitudinal follow-up of AHB patients. Serum pro-inflammatory cytokine and chemokine levels were also increased in AHB patients as compared with CHB and HC subjects. Thus, the concomitantly increased interferon-γ and cytotoxicity of NK cells were associated with liver injury and viral clearance in AHB patients.

IL-10-producing regulatory B cells in the pathogenesis of chronic hepatitis B virus infection

A regulatory subset of B cells has been found to modulate immune responses in autoimmunity, infection, and cancer, but it has not been investigated in the setting of human persistent viral infection. IL-10 is elevated in patients with chronic hepatitis B virus infection (CHB), but its cellular sources and impact on antiviral T cells have not been addressed. We investigated the role of IL-10 and regulatory B cells in the pathogenesis of CHB. Serum IL-10 levels were studied longitudinally in patients with CHB undergoing spontaneous disease flares. There was a close temporal correlation between IL-10 levels and fluctuations in viral load or liver inflammation. Blockade of IL-10 in vitro rescued polyfunctional virus-specific CD8 T cell responses. To investigate the potential contribution of regulatory B cells, their frequency was measured directly ex vivo and after exposure to stimuli relevant to hepatitis B virus (HBV) (CpG or HBV Ags). IL-10-producing B cells were enriched in patients, and their frequency correlated temporally with hepatic flares, both after stimulation and directly ex vivo. Phenotypically, these cells were predominantly immature (CD19(+)CD24(hi)CD38(hi)) ex vivo; sorted CD19(+)CD24(hi)CD38(hi) cells suppressed HBV-specific CD8 T cell responses in an IL-10-dependent manner. In summary, these data reveal a novel IL-10-producing subset of B cells able to regulate T cell immunity in CHB.

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

BACKGROUND & AIMS

In patients with chronic hepatitis B virus (HBV) infection, persistent exposure to high concentrations of antigen can disrupt T-cell functions. It is not clear to what extent long-term suppression of HBV by nucleos(t)ide analogues can restore antiviral T-cell functions. We compared HBV-specific T-cell responses of patients treated with nucleos(t)ide analogues with those detected in other conditions of HBV control.

METHODS

We analyzed intracellular levels of interferon gamma, interleukin-2, and tumor necrosis factor α in HBV-specific T cells after 10 days of stimulation with peptides covering the overall HBV genotype D sequence and ex vivo with selected CD8 epitopes and the corresponding HLA-A2 dextramers. Findings from patients treated with nucleos(t)ide analogues who had complete (HBV DNA negative/antibody to hepatitis B surface antigen positive) or partial (HBV DNA negative/hepatitis B surface antigen positive) control of their infections were compared with those of patients with spontaneous or interferon alfa-induced resolution of acute or chronic infections, inactive HBV carriers, or untreated hepatitis B e antigen-negative patients with chronic infections.

RESULTS

Although HBV-specific T cells from nucleos(t)ide analogue-treated patients with complete control of infection were dysfunctional ex vivo, they had efficient responses after in vitro expansion. These responses were comparable to those of patients who spontaneously resolved acute HBV infection. Nucleos(t)ide analogue-treated patients who were HBV DNA negative but hepatitis B surface antigen positive had lower levels of T-cell responses but responses greater than those of untreated patients with chronic infection.

CONCLUSIONS

In vitro reactivity can be restored to T cells from patients with suppressed HBV infection following long-term treatment with nucleos(t)ide analogues, despite prolonged exposure to large loads of antigen. Immune therapies that increase the antiviral T-cell response might increase the likelihood of complete HBV control in patients undergoing long-term nucleos(t)ide analogue treatment.

Regulatory T cells are the most important determinant factor of hepatitis B infection prognosis: a systematic review and meta-analysis

INTRODUCTION

Association of increased levels of CD4(+)CD25(+) regulatory T cells (Tregs) with impaired immune response and hepatitis B infection progression has been proposed. For determination of Tregs various effects among hepatitis B infected patients we performed a meta-analysis of the available literature.

METHODS

Current content, abstract books of congresses, and electronic databases were searched. Critical appraisal has been done. According to the result of heterogeneity tests (Q, I-squared, and Tau-squared), we used fix/random model for analysis.

RESULT

Twelve studies that fulfilled inclusion criteria entered to analysis. Pooled estimation of reported results showed that CD4(+)CD25(+) Tregs have higher expression of forkhead box P3 (FoxP3) versus CD4(+)CD25(-) Tregs, odd ratio (OR) was 31.49 (95% Confidence Intervals (CI): 5.09-194.94). Tregs level among chronic hepatitis B (CHB) patients was 77% (OR=1.77 95% CI: 1.43-2.19) higher than healthy controls. Patients with more than 10,000,000 HBV copies/ml have higher level of Tregs (OR: 1.24 95% CI: 1.08-1.41) comparing subjects with less than that. CHB patients have increased level of Tregs versus acute hepatitis B patients (OR=1.33 95% CI: 1.16-1.52). CD8 cells activity increased significantly after depletion of circulating Tregs (OR=1.93 CI: 1.37-2.73). Also, Tregs reduce response to treatment and non-responders to INF-α had higher level of Tregs (OR=1.60 95% CI: 1.09-2.36). In addition, Tregs increase risk of hepatocellular carcinoma (HCC) (OR=1.36 95%CI: 1.10-1.69).

CONCLUSION

Tregs influence HBV infected patients in various states. Tregs determine the disease prognosis by leading to infection progression and impairing immune response. So, Tregs are therapeutic target for immunotherapy of HBV infection.

Living in the liver: hepatic infections

The liver has vital metabolic and clearance functions that involve the uptake of nutrients, waste products and pathogens from the blood. In addition, its unique immunoregulatory functions mediated by local expression of co-inhibitory receptors and immunosuppressive mediators help to prevent inadvertent organ damage. However, these tolerogenic properties render the liver an attractive target site for pathogens. Although most pathogens that reach the liver via the blood are eliminated or controlled by local innate and adaptive immune responses, some pathogens (such as hepatitis viruses) can escape immune control and persist in hepatocytes, causing substantial morbidity and mortality worldwide. Here, we review our current knowledge of the mechanisms of liver targeting by pathogens and describe the interplay between pathogens and host factors that promote pathogen elimination and maintain organ integrity or that allow pathogen persistence.

RNA interference and its potential applications to chronic HBV treatment: results of a Phase I safety and tolerability study

BACKGROUND

RNA interference (RNAi) provides an attractive tool to modulate biological systems, and ultimately, to treat human diseases. We describe early results from a Phase Ib, first-in-human safety and tolerability study of an RNAi-based therapy, NUC B1000, among patients with mild to moderate chronic HBV.

METHODS

Three subjects received a single 5 mg DNA dose of NUC B1000 as part of a planned dose escalation study.

RESULTS

All participants reported pharyngitis, chills, myalgia and fever approximately 4-7 h after dosing. All subjects were asymptomatic after a single antipyretic dose with no symptom recurrences. Measurements of interferon (IFN)-α and -γ, interleukin (IL)-10, 12 18, 8 and 6, and tumour necrosis factor-α performed before and after dosing revealed cytokine increases before study drug administration. After drug administration, IFN-γ and IL-10 increased in two patients; IL-8 increased in one. Most increases returned to pretreatment levels within 1 week. Two patients were subsequently successfully treated with entecavir indicating that NUC B1000 does not compromise subsequent antiviral therapy.

CONCLUSIONS

Thus far, NUC B1000 appears safe and well-tolerated; safety and efficacy studies across a larger, more diverse patient spectrum using increasing doses are needed to determine its appropriate role in the antiviral armamentarium.

Kinetics of immune responses to hepatitis B virus infection

The pathogenesis of hepatitis B is mainly triggered by the host's cellular immune responses to hepatitis B virus (HBV) infection, and the immune responses against the virus depends on the interaction of various immune cells. Current research of immunity to hepatitis B infection mainly focuses on understanding the differences between patients who can control HBV infection and those with persistent infection. In this paper, we analyze how immunological events influence the development of innate and adaptive immunity needed to control HBV infection and explore the mechanisms by which high levels of viral antigens, CD4⁺ T cells, programmed death 1 (PD-1), the presence of regulatory T cells, and impaired dendritic cell functions maintain the HBV-specific immunological failure.

Cellular immune responses in patients with hepatitis B surface antigen seroclearance induced by antiviral therapy

BACKGROUND

The mechanisms by which chronic hepatitis B is completely resolved through antiviral therapy are unknown, and the contribution of acquired T cell immunity to hepatitis B surface antigen (HBsAg) seroclearance has not been investigated. Therefore, we measured the T-cell responses to core and envelope antigens in patients with HBsAg seroclearance.

METHODS

Fourteen subjects with HBsAg seroclearance following antiviral treatment for chronic hepatitis B, 7 HBeAg-positive immunotolerant HBV carriers and 9 HBeAg-negative inactive HBsAg carriers were recruited. HBV-specific T-cell responses to recombinant HBV core (rHBcAg) and envelope (rHBsAg) proteins and pools of core and envelope peptides were measured using an ELISPOT assay detecting interferon-gamma and intracellular cytokine staining (ICS) assays detecting interferon-gamma or interleukin 2.

RESULTS

Interferon-gamma ELISPOT assays showed a low frequency of weak responses to the rHBsAg and S peptide pool in the HBsAg seroclearance group, and the response frequency to the rHBcAg and the C peptide pool was higher than to the rHBsAg (P < 0.001) and S peptide pool (P = 0.001) respectively. A higher response frequency to C than S peptide pools was confirmed in the interferon-gamma ICS assays for both CD4+ (P = 0.033) and CD8+ (P = 0.040) T cells in the HBsAg seroclearance group. The responses to C and S antigens in the inactive carriers were similar.

CONCLUSIONS

There was a low frequency of CD4+ and CD8+ T cell immune responses to envelope antigens in Chinese subjects with HBsAg seroclearance following antiviral therapy. It is unlikely that these immune responses are responsible for HBsAg seroclearance in these subjects.

HBV mutations in untreated HIV-HBV co-infection using genomic length sequencing

HIV infection has a significant impact on the natural progression of hepatitis B virus (HBV) related liver disease. In HIV-HBV co-infected patients, little is known about mutations in the HBV genome, which can influence severity of liver disease. The aim of this study was to characterize and to determine the frequency of known clinically significant mutations in the HBV genomes from HIV-HBV co-infected patients and from HBV mono-infected patients. To accomplish this, genomic length HBV sequencing was performed in highly-active anti-retroviral therapy (HAART)-naïve HIV-HBV co-infected patients (n=74) and in anti-HBV therapy-naïve HBV mono-infected patients (n=55). The frequency of HBV mutations differed between the co-infected and mono-infected patients when comparing patients with the same genotype. BCP mutations A1762T and G1764A were significantly more frequent in HBV genotype C mono-infection and the -1G frameshift was significantly more frequent in co-infection and was only observed in HBV genotype A co-infection. PreS2 deletions were observed more frequently in the setting of co-infection. Further work is needed to determine if these mutational patterns influence the differences in liver disease progression in HIV-HBV co-infected and HBV mono-infected patients.

T cell immunoglobulin- and mucin-domain-containing molecule-3 (Tim-3) mediates natural killer cell suppression in chronic hepatitis B

BACKGROUND & AIMS

T cell immunoglobulin- and mucin-domain-containing molecule-3 (Tim-3) has been shown to influence autoimmune diseases; however, its function in viral infection has not been well-defined. We therefore investigated the expression and regulatory function of Tim-3 in natural killer (NK) cells in chronic Hepatitis B (CHB) infection.

METHODS

Seventy-six CHB patients, 38 healthy controls, and 18 patients with fatty liver disease (FLD) were tested for Tim-3 expression on peripheral blood mononuclear cells (PBMCs) and in the liver tissue by flow cytometry and immunohistochemical stainning. The effects of HBV infection on Tim-3 expression in NK cells and the roles of Tim-3 in regulation of NK-cell function were also studied.

RESULTS

There was a significant increase of Tim-3 expression in PBMCs, circulating NK cells and liver infiltrating lymphocytes (LILs) from CHB patients compared to that of healthy controls and FLD patients. Increased Tim-3 expression was also detected in NK92 cells that had been transfected with a HBV expression vector and NK cells isolated from the liver of HBV transgenic mice. Importantly, blockage of Tim-3 signaling with anti-Tim-3 antibodies or Tim-3-Fc fusion proteins resulted in an increased cytotoxicity for NK92 cells compared to HepG2 and HepG2.2.15 cells, as well as an elevated interferon-gamma (IFN-gamma) production. Similarly, enhanced cytotoxicity was also observed in PBMCs or NK cells from CHB patients treated with the Tim-3 blockade ex vivo.

CONCLUSION

HBV infection can up-regulate Tim-3 expression in NK cells, which may in turn suppress NK-cell functions in CHB patients.

Antiviral intrahepatic T-cell responses can be restored by blocking programmed death-1 pathway in chronic hepatitis B

BACKGROUND & AIMS

The antiviral function of peripheral hepatitis B virus (HBV)-specific T cells can be increased in patients with chronic hepatitis B by blocking the interaction of programmed death (PD)-1 with its ligand PD-L1. However, no information is available about the effects of this blockade on intrahepatic lymphocytes. We studied T-cell exhaustion and the effects of PD-1/PD-L1 blockade on intrahepatic and circulating HBV-specific T cells in patients with chronic hepatitis B.

METHODS

A total of 42 patients with chronic HBV infection who underwent liver biopsy were studied. The ex vivo phenotype of peripheral and intrahepatic HBV-specific CD8(+) T cells was assessed by flow cytometry with class I tetramers and antibodies to T-cell differentiation molecules. Functional recovery was evaluated by analyzing expansion and production of interferon (IFN)-gamma and interleukin (IL)-2 after short-term incubation of T cells with HBV peptides in the presence of anti-PD-L1 or control antibodies.

RESULTS

Intrahepatic HBV-specific CD8(+) cells expressed higher levels of PD-1 and lower levels of CD127 than their peripheral counterparts. Blockade of PD-1/PD-L1 interaction increased CD8(+) cell proliferation and IFN-gamma and IL-2 production by circulating intrahepatic lymphocytes, even though anti-PD-L1 had a stronger effect on intrahepatic compared with peripheral T cells.

CONCLUSIONS

T-cell exhaustion by high antigen concentrations promotes HBV-specific T-cell dysfunction by affecting phenotype and function of peripheral and intrahepatic T cells. By restoring antiviral T-cell functions, not only in peripheral but also in intrahepatic lymphocytes, anti-PD-L1 might be a good therapeutic candidate for chronic HBV infection.

No increase in hepatitis B virus (HBV)-specific CD8+ T cells in patients with HIV-1-HBV coinfections following HBV-active highly active antiretroviral therapy

Following treatment of hepatitis B virus (HBV) monoinfection, HBV-specific T-cell responses increase significantly; however, little is known about the recovery of HBV-specific T-cell responses following HBV-active highly active antiretroviral therapy (HAART) in HIV-HBV coinfected patients. HIV-HBV coinfected patients who were treatment naïve and initiating HBV-active HAART were recruited as part of a prospective cohort study in Thailand and followed for 48 weeks (n = 24). Production of gamma interferon (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) in both HBV- and HIV-specific CD8(+) T cells was quantified using intracellular cytokine staining on whole blood. Following HBV-active HAART, the median (interquartile range) log decline from week 0 to week 48 for HBV DNA was 5.8 log (range, 3.4 to 6.7) IU/ml, and for HIV RNA it was 3.1 (range, 2.9 to 3.5) log copies/ml (P < 0.001 for both). The frequency of HIV Gag-specific CD8(+) T-cell responses significantly decreased (IFN-gamma, P < 0.001; TNF-alpha, P = 0.05). In contrast, there was no significant change in the frequency (IFN-gamma, P = 0.21; TNF-alpha, P = 0.61; and IFN-gamma and TNF-alpha, P = 0.11) or magnitude (IFN-gamma, P = 0.13; TNF-alpha, P = 0.13; and IFN-gamma and TNF-alpha, P = 0.13) of HBV-specific CD8(+) T-cell responses over 48 weeks of HBV-active HAART. Of the 14 individuals who were HBV e antigen (HBeAg) positive, 5/14 (36%) lost HBeAg during the 48 weeks of follow-up. HBV-specific CD8(+) T cells were detected in 4/5 (80%) of patients prior to HBeAg loss. Results from this study show no sustained change in the HBV-specific CD8(+) T-cell response following HBV-active HAART. These findings may have implications for the duration of treatment of HBV in HIV-HBV coinfected patients, particularly in HBeAg-positive disease.

Impaired TLR3/IFN-beta signaling in monocyte-derived dendritic cells from patients with acute-on-chronic hepatitis B liver failure: relevance to the severity of liver damage

Toll-like receptors (TLRs) are a class of proteins that play key roles in innate immunity through recognition of microbial components. TLR3 is expressed abundantly in dendritic cells, and is responsible for recognizing viral pathogens and inducing interferon beta (IFN-beta) production. Although TLR3 has been reported to be involved in several diseases caused by viral infections, its role in hepatitis B virus (HBV)-induced hepatitis is still largely unknown. We found that expression of TLR3 and IFN-beta was decreased significantly in monocyte-derived dendritic cells (MoDCs) from patients with chronic hepatitis B (CHB, n=40) or acute-on-chronic hepatitis B liver failure (ACHBLF, n=60), compared with normal controls (n=20). We observed a further decrease in TLR3 and IFN-beta in ACHBLF compared to CHB patients. Compared with surviving patients, TLR3 and IFN-beta expression was significantly lower in non-surviving ACHBLF patients, which strongly indicated a correlation between TLR3 signaling impairment in MoDCs and disease severity in ACHBLF patients. Further linear correlation analysis demonstrated significant correlations between expression of TLR3 signaling components (TLR3 and IFN-beta) and disease severity markers (prothrombin activity and total bilirubin) for individual ACHBLF patients. To the best of our knowledge, this is the first study to show that MoDC impairment is correlated with severe liver damage in ACHBLF patients, which suggests the potential of TLR3/IFN-beta expression in MoDCs as a diagnostic marker.

Host immunity influences disease progression and antiviral efficacy in humans infected with hepatitis B virus

Hepatitis B virus (HBV) infection can lead to several severe liver diseases, including hepatitis, cirrhosis and hepatocellular carcinoma, although the underlying mechanisms responsible for the clinical outcome have not been well characterized. In this review, we retrospectively examine the history of immunological responses to HBV infection and summarize the current understanding of innate and adaptive immunity in the context of HBV-associated liver disease. Recent data indicate that the interaction between HBV and the host immune response not only substantially drives disease progression, but also significantly influences antiviral efficacy in HBV-infected individuals. Advances in the field have provided insight into the immunopathology of HBV infection. Based on the characteristics of host immune responses in patients with HBV infection, a 'climbing slope hypothesis' is proposed to suggest that therapeutic strategies aimed at modulating the immune activity of the host may represent a complementary approach to antiviral drug treatment for the management of chronically HBV-infected patients.

HBV-Specific Adaptive Immunity

The successful control of HBV infection requires an efficient expansion of distinct elements of the adaptive immune system (B cells, helper and cytotoxic T cells) that, due to the hepatotropic nature of HBV, need to operate in the liver parenchyma. In this respect, we will discuss broad features of HBV immunity in patients with resolved or chronic HBV infection and analyze how the liver environment can directly modulate HBV-immunity.

Impaired quality of the hepatitis B virus (HBV)-specific T-cell response in human immunodeficiency virus type 1-HBV coinfection

Hepatitis B virus (HBV)-specific T cells play a key role both in the control of HBV replication and in the pathogenesis of liver disease. Human immunodeficiency virus type 1 (HIV-1) coinfection and the presence or absence of HBV e (precore) antigen (HBeAg) significantly alter the natural history of chronic HBV infection. We examined the HBV-specific T-cell responses in treatment-naïve HBeAg-positive and HBeAg-negative HIV-1-HBV-coinfected (n = 24) and HBV-monoinfected (n = 39) Asian patients. Peripheral blood was stimulated with an overlapping peptide library for the whole HBV genome, and tumor necrosis factor alpha and gamma interferon cytokine expression in CD8+ T cells was measured by intracellular cytokine staining and flow cytometry. There was no difference in the overall magnitude of the HBV-specific T-cell responses, but the quality of the response was significantly impaired in HIV-1-HBV-coinfected patients compared with monoinfected patients. In coinfected patients, HBV-specific T cells rarely produced more than one cytokine and responded to fewer HBV proteins than in monoinfected patients. Overall, the frequency and quality of the HBV-specific T-cell responses increased with a higher CD4+ T-cell count (P = 0.018 and 0.032, respectively). There was no relationship between circulating HBV-specific T cells and liver damage as measured by activity and fibrosis scores, and the HBV-specific T-cell responses were not significantly different in patients with either HBeAg-positive or HBeAg-negative disease. The quality of the HBV-specific T-cell response is impaired in the setting of HIV-1-HBV coinfection and is related to the CD4+ T-cell count.

Liver biopsy findings in chronic hepatitis B

Liver biopsy plays a central role in treatment algorithms in patients with hepatitis B and remains the gold standard for evaluating hepatic pathology. The pathology of hepatitis B is diverse and reflects the natural history of infection. An acute hepatitic pattern with lobular disarray is seen in acute infection, during acute flares of disease, and with acute hepatitis D superinfection. In chronic hepatitis B, inflammation is less pronounced in the immune-tolerant phase and is prominent during immune-mediated viral clearance. Active inflammation appears to be the driving force for development of fibrosis. Inflammatory grades and fibrosis stage are assigned as is done for hepatitis C. Although current management guidelines recommend liver biopsies only in select patients based on age, viral levels, and hepatitis B e antigen status, these clinical and biochemical parameters do not show consistent correlations with liver histology. Liver biopsy also helps identify preneoplastic lesions including large cell and small cell change. Unlike in other causes of chronic hepatitis, immunostains are widely used and can help determine the phase of infection. Liver biopsies can also identify additional pathology that may contribute to liver disease such as steatohepatitis, iron overload, autoimmune hepatitis, and drug-induced injury. Thus, liver biopsy can play an important role in staging and grading chronic hepatitis B and should be more widely used in assessing the need for therapy.

Peripheral virus-specific T-cell interleukin-10 responses develop early in acute hepatitis C infection and become dominant in chronic hepatitis

BACKGROUND/AIMS

Interleukin-10 (IL-10) has been ascribed pro-viral but anti-fibrotic properties in chronic hepatitis C virus (HCV) infection. In this study, we examined the role of HCV-specific T-cell IL-10 response in patients with acute and chronic HCV infection.

METHODS

Peripheral HCV-specific T-cell IL-10 and IFNgamma responses were measured in cytokine Elispot assay using overlapping HCV-derived peptides in patients with chronic (n=61), resolved (n=15) and acute (n=8) hepatitis C, looking for their onset, quantity, breadth and durability relative to clinical and virological outcomes. The source and effect of HCV-specific IL-10 response were determined in depletion and IL-10 neutralization experiments.

RESULTS

Both HCV-specific IL-10 and IFNgamma responses were detected early within 1-2 months of acute clinical hepatitis C. However, only HCV-specific IL-10 response correlated with elevated liver enzymes, increased viremia and suppressed HCV-specific CD4(+) T-cell proliferation in acute infection. While these associations were lost in established chronic infection, HCV-specific IL-10 responses were increased in patients without cirrhosis while IL-10 blockade enhanced antiviral effector IFNgamma responses.

CONCLUSIONS

HCV-specific IL-10 Tr1 responses may play a dual role in HCV infection, dampening effector T-cells to promote viral persistence in acute infection but also protecting against progressive fibrosis in chronic infection.