Hepatitis B core antigen stimulates interleukin-10 secretion by both T cells and monocytes from peripheral blood of patients with chronic hepatitis B virus infection

The Role of Interleukins in HBV Infection: A Narrative Review

Hepatitis B virus (HBV) infection is a worldwide medical issue with significant morbidity and mortality, as it is the main cause of chronic liver disease and hepatocellular carcinoma (HCC). Both innate and adaptive immune responses play a key role in HBV replication and suppression. Recently, the pathophysiological function of interleukins (IL) in the natural course of HBV has gained much attention as a result of the broad use of anti-interleukin agents for a variety of autoimmune diseases and the accompanying risk of HBV reactivation. We present a narrative review regarding the role of IL in HBV infection. Collectively, the pro-inflammatory ILs, namely IL-1, IL-5, IL-6, IL-12 and IL-21, seem to play a critical role in the suppression of HBV replication. In contrast, the anti-inflammatory cytokines IL-10, IL-23 and IL-35 probably act as HBV replication enhancers, while IL-17 has been correlated with HBV-related liver injury. Interestingly enough, IL-2, IL-4 and IL-12 have been tried as therapeutic options against HBV infection with contradictory results. Lastly, the role of IL-22 remains largely ill defined, although preliminary data suggest that it may play a significant role in HBV replication, proliferation and subsequent liver damage.

Systemic cytokine and viral antigen-specific responses in hepatitis D virus RNA positive versus HDV RNA negative patients

Background

Hepatitis B virus (HBV)/Hepatitis D Virus (HDV) co-infection increases the risk of severe liver disease compared to HBV mono-infection. Adaptive immune responses to HDV are weakly detectable, and the involvement of innate immunity in the progression of HDV-related liver fibrosis is suggested. We hypothesize that an overall innate immune activation in HBV/HDV co-infection plays a role in liver disease progression and also impacts virus specific T cell response.

Methods

Sixteen HBV/HDV-co-infected-patients (median age 42y/7F/6 Asian/4 White/6 Black/15 HBeAg-) and 8 HBV monoinfected-patients (median age 39y/4F/4 Asian/3 Black/1 White/HBeAg-) with median follow-up of 5 years were enrolled. Liver fibrosis was assessed by liver stiffness measurement (LSM, FibroScan®). Proliferation of CD3 + CD4+ T cells in response to viral antigens using CFSE assays and cytokine secreting monocytes was analyzed by flow cytometry.

Results

Of 16 HBV/HDV, 11 were HDV-RNA+ (HBV-DNA 0-1,040 IU/mL), 5/11 Interferon (IFN) + Nucleos/tide Analog (NA), 3/11 NA monotherapy, median ALT 77 U/L at the time of sample collection, median LSM of 9.8. In 5 HDV RNA-, median HBV DNA 65 IU/mL, 4/5 prior IFN and/or NA, ALT 31 U/L, and median LSM 8.5 kPa. In 8 HBV controls, median HBV-DNA, ALT, LSM was 69 IU/mL, 33 U/L,5 kPa, respectively. PBMC stimulation with HBV core antigen (HBcAg) and HDV antigen (HDAg) showed weaker CD3 + CD4 + T-cell proliferation in HDV-RNA+ vs. HDV RNA- and HBV-mono-infected patients (p < 0.05). In HDV-RNA+ patients, a correlation between ALT and TNF-α (r = 0.76, p = 0.008), higher IL-10 levels and increased proportion of CD14 + TNF-α+ cells were found.

Conclusion

In summary, during HBV/HDV coinfection, HDV RNA+ patients had weaker HBV and HDV specific responses, associated with increased TNF-α + monocytes irrespective of IFN treatment.

System Biology Investigation Revealed Lipopolysaccharide and Alcohol-Induced Hepatocellular Carcinoma Resembled Hepatitis B Virus Immunobiology and Pathogenesis

Hepatitis B infection caused by the hepatitis B virus is a life-threatening cause of liver fibrosis, cirrhosis, and hepatocellular carcinoma. Researchers have produced multiple in vivo models for hepatitis B virus (HBV) and, currently, there are no specific laboratory animal models available to study HBV pathogenesis or immune response; nonetheless, their limitations prevent them from being used to study HBV pathogenesis, immune response, or therapeutic methods because HBV can only infect humans and chimpanzees. The current study is the first of its kind to identify a suitable chemically induced liver cirrhosis/HCC model that parallels HBV pathophysiology. Initially, data from the peer-reviewed literature and the GeneCards database were compiled to identify the genes that HBV and seven drugs (acetaminophen, isoniazid, alcohol, D-galactosamine, lipopolysaccharide, thioacetamide, and rifampicin) regulate. Functional enrichment analysis was performed in the STRING server. The network HBV/Chemical, genes, and pathways were constructed by Cytoscape 3.6.1. About 1546 genes were modulated by HBV, of which 25.2% and 17.6% of the genes were common for alcohol and lipopolysaccharide-induced hepatitis. In accordance with the enrichment analysis, HBV activates the signaling pathways for apoptosis, cell cycle, PI3K-Akt, TNF, JAK-STAT, MAPK, chemokines, NF-kappa B, and TGF-beta. In addition, alcohol and lipopolysaccharide significantly activated these pathways more than other chemicals, with higher gene counts and lower FDR scores. In conclusion, alcohol-induced hepatitis could be a suitable model to study chronic HBV infection and lipopolysaccharide-induced hepatitis for an acute inflammatory response to HBV.

Specialized Pro-Resolving Lipid Mediators: Endogenous Roles and Pharmacological Activities in Infections

During an infection, inflammation mobilizes immune cells to eliminate the pathogen and protect the host. However, inflammation can be detrimental when exacerbated and/or chronic. The resolution phase of the inflammatory process is actively orchestrated by the specialized pro-resolving lipid mediators (SPMs), generated from omega-3 and -6 polyunsaturated fatty acids (PUFAs) that bind to different G-protein coupled receptors to exert their activity. As immunoresolvents, SPMs regulate the influx of leukocytes to the inflammatory site, reduce cytokine and chemokine levels, promote bacterial clearance, inhibit the export of viral transcripts, enhance efferocytosis, stimulate tissue healing, and lower antibiotic requirements. Metabolomic studies have evaluated SPM levels in patients and animals during infection, and temporal regulation of SPMs seems to be essential to properly coordinate a response against the microorganism. In this review, we summarize the current knowledge on SPM biosynthesis and classifications, endogenous production profiles and their effects in animal models of bacterial, viral and parasitic infections.

The multifaceted nature of IL-10: regulation, role in immunological homeostasis and its relevance to cancer, COVID-19 and post-COVID conditions

Interleukin-10 (IL-10) is a pleiotropic cytokine that has a fundamental role in modulating inflammation and in maintaining cell homeostasis. It primarily acts as an anti-inflammatory cytokine, protecting the body from an uncontrolled immune response, mostly through the Jak1/Tyk2 and STAT3 signaling pathway. On the other hand, IL-10 can also have immunostimulating functions under certain conditions. Given the pivotal role of IL-10 in immune modulation, this cytokine could have relevant implications in pathologies characterized by hyperinflammatory state, such as cancer, or infectious diseases as in the case of COVID-19 and Post-COVID-19 syndrome. Recent evidence proposed IL-10 as a predictor of severity and mortality for patients with acute or post-acute SARS-CoV-2 infection. In this context, IL-10 can act as an endogenous danger signal, released by tissues undergoing damage in an attempt to protect the organism from harmful hyperinflammation. Pharmacological strategies aimed to potentiate or restore IL-10 immunomodulatory action may represent novel promising avenues to counteract cytokine storm arising from hyperinflammation and effectively mitigate severe complications. Natural bioactive compounds, derived from terrestrial or marine photosynthetic organisms and able to increase IL-10 expression, could represent a useful prevention strategy to curb inflammation through IL-10 elevation and will be discussed here. However, the multifaceted nature of IL-10 has to be taken into account in the attempts to modulate its levels.

Suppression of Interferon-α Treatment Response by Host Negative Factors in Hepatitis B Virus Infection

Chronic hepatitis B virus (CHB) infection remains a major global public health issue for which there is still lacking effective curative treatment. Interferon-α (IFN-α) and its pegylated form have been approved as an anti-HBV drug with the advantage of antiviral activity and host immunity against HBV infection enhancement, however, IFN-α treatment failure in CHB patients is a challenging obstacle with 70% of CHB patients respond poorly to exogenous IFN-α treatment. The IFN-α treatment response is negatively regulated by both viral and host factors, and the role of viral factors has been extensively illustrated, while much less attention has been paid to host negative factors. Here, we summarized evidence of host negative regulators and parameters involved in IFN-α therapy failure, review the mechanisms responsible for these effects, and discuss the possible improvement of IFN-based therapy and the rationale of combining the inhibitors of negative regulators in achieving an HBV cure.

Beyond Metabolism: Role of the Immune System in Hepatic Toxicity

The liver is primarily thought of as a metabolic organ; however, the liver is also an important mediator of immunological functions. Key perspectives on this emerging topic were presented in a symposium at the 2018 annual meeting of the American College of Toxicology entitled "Beyond metabolism: Role of the immune system in hepatic toxicity." Viral hepatitis is an important disease of the liver for which insufficient preventive vaccines exist. Host immune responses inadequately clear these viruses and often potentiate immunological inflammation that damages the liver. In addition, the liver is a key innate immune organ against bacterial infection. Hepatocytes and immune cells cooperatively control systemic and local bacterial infections. Conversely, bacterial infection can activate multiple types of immune cells and pathways to cause hepatocyte damage and liver injury. Finally, the immune system and specifically cytokines and drugs can interact in idiosyncratic drug-induced liver injury. This rare disease can result in a disease spectrum that ranges from mild to acute liver failure. The immune system plays a role in this disease spectrum.

Immunotherapy of hepatocellular carcinoma: Unique challenges and clinical opportunities

Current therapies for advanced hepatocellular carcinoma (HCC) are marginally effective and exacerbate underlying liver disease. The ability of immunotherapy to elicit nontoxic, systemic, long-lived anti-tumor activity makes it particularly well-suited for use in the setting of HCC. While therapeutic benefit has been achieved in early clinical trials, the efficacy of immune-based therapies is limited by several unique properties of HCC, most notably the inherently tolerogenic character of the liver in both healthy and diseased (chronically-infected or tumor-bearing) states. Therapeutic regimens that both counteract these immunosuppressive mechanisms and amplify tumor-specific immunity are expected to profoundly improve clinical outcomes for HCC patients.

Immunotherapy of hepatocellular carcinoma: Unique challenges and clinical opportunities

Current therapies for advanced hepatocellular carcinoma (HCC) are marginally effective and exacerbate underlying liver disease. The ability of immunotherapy to elicit nontoxic, systemic, long-lived anti-tumor activity makes it particularly well-suited for use in the setting of HCC. While therapeutic benefit has been achieved in early clinical trials, the efficacy of immune-based therapies is limited by several unique properties of HCC, most notably the inherently tolerogenic character of the liver in both healthy and diseased (chronically-infected or tumor-bearing) states. Therapeutic regimens that both counteract these immunosuppressive mechanisms and amplify tumor-specific immunity are expected to profoundly improve clinical outcomes for HCC patients.

Effectiveness and safety of toripalimab, camrelizumab, and sintilimab in a real-world cohort of hepatitis B virus associated hepatocellular carcinoma patients

BACKGROUND

The clinical significance of programmed cell death protein-1 (PD-1)-targeted immunotherapy in Chinese patients is understudied. We thus aimed to evaluate the safety and efficacy of PD-1 inhibitors with toripalimab, camrelizumab or sintilimab for Chinese hepatocellular carcinoma (HCC) patients in a real-life cohort.

METHODS

We analysed hepatitis B virus (HBV)-associated HCC patients treated with toripalimab, camrelizumab, or sintilimab in a retrospective single-center cohort from November 2018 to June 2020. Efficacy was evaluated with objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), time to tumor progression (TTP), and overall survival (OS). Safety data were also recorded.

RESULTS

Seventy patients were finally included in the analysis: 23 were treated with toripalimab, 33 with camrelizumab, and 14 with sintilimab. The mean duration of follow-up was 44.7 (95% CI: 39.9-49.6) weeks and the mean cycles of PD-1 at cutoff were 8.3±8.0 for all patients. The ORR and DCR for the whole cohort were 30% and 72.9%, respectively. Overall, 25 (35.7%) patients had radiological disease progression and 10 (14.3%) patients died during follow-up. Median PFS, median TTP, and median OS had not yet been reached. Most frequent drug-related adverse events (AEs) were rash (27.1%), hypertension (18.6%), fatigue (17.1%), diarrhea (17.1%), paresthesia (15.7%), and nausea (15.7%).

CONCLUSIONS

Our findings suggest that (I) PD-1 targeted immunotherapy with toripalimab, camrelizumab, or sintilimab yielded a promising outcome in Chinese HBV patients with HCC and that (II) immunotherapy was well tolerated generally and had manageable side effects. This approach thus warrants further popularization and application in clinical practice.

Genetic variation in IL-10 influences the progression of hepatitis B infection

OBJECTIVES

The outcomes of hepatitis B virus (HBV) infection vary substantially among affected individuals, providing evidence of the role of host genetic background in the susceptibility to HBV persistence and the dynamics of liver injury progression to cirrhosis and hepatocellular carcinoma (HCC).

METHODS

Six single-nucleotide polymorphisms within the interleukin 10 gene (IL10) were genotyped by MALDI-TOF mass spectrometry in 857 patients with chronic HBV infection (CHB), 48 patients with resolved HBV infection, and 100 healthy volunteers. Associations of the selected polymorphisms with susceptibility to chronic HBV infection, liver injury progression, and outcomes were investigated.

RESULTS

IL10 -819T (rs1800871), -592A (rs1800872), and +504T (rs3024490) alleles were associated with treatment-induced hepatitis B surface antigen (HBsAg) seroclearance. Additionally, IL10 ATAC haplotype increased the chance of HBsAg loss and was significantly more frequent in patients with less liver injury. Moreover rs1800871TT, rs1518110TT, rs1800872AA, and rs3024490TT genotypes were identified as predictors of a lower FIB-4 score (<0.5).

CONCLUSIONS

This study indicates that polymorphisms within the promoter region and intronic sequences of IL10 are associated with chronicity of hepatitis B and with HBV-induced liver damage.

Hepatitis B Core Antigen Impairs the Polarization While Promoting the Production of Inflammatory Cytokines of M2 Macrophages via the TLR2 Pathway

Although several evidences suggesting the vital roles that innate immunity plays in the persistence and elimination of chronic hepatitis B virus (CHB) infection, the exact mechanism is still complicated. Here, we successfully polarized monocytes derived from healthy human peripheral blood mononuclear cells (PBMCs) into M1/M2 macrophages and detected the effects of hepatitis B core antigen (HBcAg) on the polarization and function of macrophages via the Toll-like receptor (TLR) 2 signaling pathway. The results showed that HBcAg had a negligible impact on M1 polarization, while it effectively impaired M2 polarization and promoted the production of pro-inflammatory cytokines such as IL-6 and TNF-α. Additionally, HBcAg treatment increased TLR2 expression on M2 macrophages and TLR2 blockade abolished the effects of HBcAg on the impaired phenotype and pro-inflammatory cytokine productions of M2 macrophages. Signaling pathway analysis revealed that the nuclear factor κB (NF-κB) pathway, the downstream of TLR2, was upregulated upon HBcAg treatment in both M1 and M2 macrophages. Furthermore, a CD8⁺ T-macrophage coculture system implied that compared with PBS stimulation, HBcAg-stimulated M2 macrophages regained their ability to activate CD8⁺ T cells with higher secretion of IFN-γ. Finally, we found impaired expression of M2-related molecules and increased levels of pro-inflammation cytokines in M2 macrophages from CHB patients upon HBcAg stimulation. In conclusion, these results imply a favorable role of HBcAg in the establishment of a pro-inflammatory microenvironment by macrophages, which may suggest a potential therapeutic strategy of HBcAg-induced macrophage activation in CHB infection.

Differential Expression of Immune Inhibitory Checkpoint Signatures on Antiviral and Inflammatory T Cell Populations in Chronic Hepatitis B

Virus-specific T cells are critical in mediating the pathogenesis of hepatitis B virus (HBV) infection. Interferon gamma (IFNγ)-producing T cells are associated with resolution; in contrast, interleukin-17 (IL-17)-producing T cells are linked to exacerbation of liver inflammation and injury. Checkpoint receptors stringently regulate T cell functions, with their expression profiles varying on different T cell subsets. Blockade of checkpoint receptors may be an effective therapeutic strategy for chronic hepatitis B (CHB); however, blockade may also inadvertently exacerbate proinflammatory responses. In this study, we sought to determine the balance of inflammatory and antiviral T cells and determine their inhibitory receptor profile. The frequency of total and HBV antigen-specific Th17 and Tc17 cells was higher in CHB patients compared with healthy controls (HCs). Th17 and Tc17 cells in CHB patients had significantly lower expression of T cell immunoglobulin and mucin domain protein-3 (TIM-3) compared with HCs, with no difference in programmed death-1 (PD-1) or CD244 expression. Conversely, Th1 and Tc1 cells in CHB patients hyperexpressed PD-1 and CD244, while TIM-3 expression was comparable in both cohorts. During CHB, antiviral IFNγ T cells hyperexpress multiple immune inhibitory receptors driving their functional impairment. In contrast, inflammatory Th17/Tc17 cells hypoexpress TIM-3, but not PD-1 or CD244. Checkpoint inhibitors for CHB should target PD-1 or CD244 to allow restoration of IFNγ responses without affecting inflammatory IL-17 production.

Immune Exhaustion: Past Lessons and New Insights from Lymphocytic Choriomeningitis Virus

Lymphocytic choriomeningitis virus (LCMV) is a paradigm-forming experimental system with a remarkable track record of contributing to the discovery of many of the fundamental concepts of modern immunology. The ability of LCMV to establish a chronic infection in immunocompetent adult mice was instrumental for identifying T cell exhaustion and this system has been invaluable for uncovering the complexity, regulators, and consequences of this state. These findings have been directly relevant for understanding why ineffective T cell responses commonly arise during many chronic infections including HIV and HCV, as well as during tumor outgrowth. The principal feature of exhausted T cells is the inability to elaborate the array of effector functions necessary to contain the underlying infection or tumor. Using LCMV to determine how to prevent and reverse T cell exhaustion has highlighted the potential of checkpoint blockade therapies, most notably PD-1 inhibition strategies, for improving cellular immunity under conditions of antigen persistence. Here, we discuss the discovery, properties, and regulators of exhausted T cells and highlight how LCMV has been at the forefront of advancing our understanding of these ineffective responses.

Effector functions of memory CTLs can be affected by signals received during reactivation

Memory cytotoxic T lymphocytes (CTLs) are able to provide protections to the host against repeated insults from intracellular pathogens. However, it has not been completely understood how the effector functions of memory CTLs are induced upon antigen challenge, which is directly related to the efficacy of their protection. Third signal cytokines, such as IL-12 and type I interferon, have been suggested to be involved in the protective function of memory CTLs, but direct evidence is warranted. In this report, we found that memory CTLs need to be reactivated to exert effector functions. Infusion of a large population of quiescent memory CTLs did not lead to cancer control in tumor-bearing mice, whereas infusion of a reactivated memory CTL population did. This reactivation of memory CTLs requires cytokines such as IL-12 in addition to antigen but was less dependent upon costimulation and IL-2 compared to naive CTLs. Memory CTLs responded more quickly and with greater strength than their naive counterparts upon stimulation, which is associated with higher upregulation of important transcription factors such as T-bet and phosphorylated STAT4. In addition, memory CTLs underwent less expansion than naive CTLs upon pathogen challenge. In conclusion, effector functions of established memory CTLs may be affected by certain cytokines such as IL-12 and type I IFN. Thus, a pathogen's ability to induce cytokines could contribute to the efficacy of protection of an established memory CTL population.

Influence of single nucleotide polymorphisms of cytokine genes on anti-HBs antibody production after hepatitis B vaccination in a Japanese young adult population

Hepatitis B (HB) vaccination is one of the most efficient tools to prevent the transmission of the virus. Considerable variability exists in HB vaccine responses, with 5-10% of healthy Japanese adults demonstrating no response following a standard vaccination. Recently, polymorphisms of immune-regulatory genes, such as cytokine genes, have been reported to influence the immune response to HB vaccine. The aim of this study was to investigate the underlying mechanisms of the genetic association between several cytokine gene polymorphisms and the immune response to HB vaccination in a Japanese population. One hundred and twenty three vaccinated young adults were classified according to the level of antibody-titer (anti-HBs). Single nucleotide polymorphism typing for IFN-γ (+874, 3'-UTR), IL-10 (-591, -819, -1082), and TNF-α (-308, -857), was accomplished using the PCR-RFLP or SSP-PCR method. The TNF-α (-857) CC type and the IL-10 (-1082) AG type were present more frequently in the low titer group than in the high titer group. The TNF-α (-857) CC type was found to be significantly associated with low response of serum anti-HBs. The anti-HBs antibody was not readily produced in the IL-10 (-1082) AG and TNF-α (-857) CC haplotype. Conversely, the antibody was readily produced in the IL-10 (-1082) AA and TNF-α (-857) CC haplotype, and the IL-10 (-1082) AA and TNF-α (-857) CT haplotype, suggesting a high likelihood of the IL-10 (-1082) AG type to be included in the low anti-HBs group, and high anti-HBs antibody production in those with the TNF-α (-857) CT type. These SNPs may produce ethnically-specific differences in the immune response to HB vaccine in the Japanese population. J. Med. Invest. 63: 256-261, August, 2016.

Hepatitis B virus infection is associated with younger median age at diagnosis and death in cancers

Several non-hepatocellular cancers were linked with hepatitis B virus (HBV) infection. This study was aimed to quantify the potential associations between HBV infection and multiple non-hepatocellular cancers. Continuous cases, including 5,715 non-cancer and 40,963 cancer cases diagnosed from 2008 to 2014 in Sun Yat-sen University Cancer Center were analyzed. HBV DNA and hepatitis B core antigen (HBcAg) were examed in gastric cancer tissues by polymerase chain reaction and immunohistochemical staining. After adjusting for age, sex, year of diagnosis, smoking, drinking and family history of cancer, significant associations were found between serum HBsAg and frequently reported HBV-related non-hepatocellular cancers, including non-Hodgkin's lymphoma, cholangiocarcinoma and pancreatic cancer [adjusted odds ratio (AOR) and 95% confidence interval (CI): 1.89 (1.65-2.16)], as well as total other non-hepatocellular cancers [AOR and 95% CI: 1.12 (1.03-1.22)]. The median ages at diagnosis, all-cause death and cancer-specific death of serum HBsAg positive cancer patients were all significantly younger than those with serum HBsAg negative. HBV DNA was detected in 12.4% (34/275) gastric cancer tissues and HBcAg was most commonly detected in lymphocytes. This was the first report that HBV infection had a modest but significant nonspecific association with total non-hepatocellular cancers. Median age at diagnosis and death was significantly younger in serum HBsAg positive cancer patients. The underlying mechanism needs further investigation.

Immune Regulation by T Regulatory Cells in Hepatitis B Virus-Related Inflammation and Cancer

Hepatocellular carcinoma (HCC) is the leading cause of cancer death, and hepatitis B virus (HBV) infection is one of the commonest causes in Asian countries. India has the second largest pool after China for hepatitis B-infected subjects. HBV clearance is T cell dependent, and one of the reasons for T cells hyporesponsiveness is due to mass production of regulatory T cells (Tregs) through activation of Notch signalling, which suppress CD4/CD8 T cells. Tregs are important to maintain cellular homoeostasis; however, during viral infection increase of Tregs is inversely proportional to HBV DNA titres. Tregs exert their suppressive effect either via cell-to-cell contact or through release of interleukin (IL)-2, IL-10, TGF-β and IL-35. In Chronic hepatitis B virus CHBV infection, PD-1 pathway also gets activated and is involved in promoting tolerance. However, with Tregs induction, virus-specific T cell responses also get decreased. Circulatory and intratumoural Tregs promote development of HBV-specific HCC more by decreasing and impairing the effector functions of CD8 T cells. Antiviral therapies and PD-1 blockade strategy had shown the inhibition of Tregs and reduction in HBV DNA. However, inhibition of HBV-specific Tregs is major challenge for future therapies. New cytokine blockade therapies have emerged as potential therapeutic potentials.

Hepatitis B immunopathogenesis and immunotherapy

Worldwide there are over 248 million chronic carriers of HBV of whom about a third eventually develop severe HBV-related complications. Due to the major limitations of current therapeutic approaches, the development of more effective strategies to improve therapeutic outcomes in chronic hepatitis B (CHB) patients seems crucial. Immune activation plays a critical role in spontaneous viral control; therefore, new modalities based on stimulation of the innate and adaptive immune responses could result in the resolution of infection and are promising approaches. Here, we summarize the HBV immunopathogenesis, and discuss the encouraging results obtained from the promising immune-based innovations, such as therapeutic vaccination, cytokine therapy, cell-based therapies and blocking inhibitory receptors, as current and future immunotherapeutic interventions.

The Effect of Hepatitis B Virus on Graft and Overall Survival in Kidney Transplant Patients

OBJECTIVES

We investigated the effect of hepatitis B virus in kidney transplant patients in terms of patient care and survival.

MATERIALS AND METHODS

We retrospectively analyzed kidney transplant patients from 1993 to 2013. A control group with negative serology was selected. The hepatitis B virus-positive group was divided into 2 subgroups based on serologic status, treatments, and treatment responses. Group A had viral suppression, and group B had hepatitis B virus DNA persistence. Overall and allograft survival rates were compared.

RESULTS

We identified 32 hepatitis B virus-positive and 74 hepatitis B virus-negative patients. Positive group was treated with lamivudine (n = 23), lamivudine plus entecavir (n = 4), lamivudine plus tenofovir (n = 4), or lamivudine plus entecavir and tenofovir (n = 1). In group A (n = 15), antiviral treatment was given based on the presence of either hepatitis B surface antigen with negative hepatitis B virus DNA (n = 11) or hepatitis B virus DNA positivity (n = 4). Group B patients (n = 17) received antiviral treatment for persistence of hepatitis B virus DNA (n = 7) or for viral reactivation (ie, recurrence of hepatitis B virus DNA) (n = 10). Groups A and B did not differ significantly in terms of graft or overall survival. Liver biopsy was performed in 17 patients; 3 patients had high-grade fibrosis or cirrhosis, and 14 patients had normal histology or mild hepatitis. Median graft survival time was longer in positive group (69.5 mo vs 54 mo; P = .007). Five- and 10-year overall survival rates were comparable (89%-84% vs 96%-96%; P = .107).

CONCLUSIONS

Hepatitis B virus-positive kidney transplant patients have increased liver transaminase levels, longer graft survival times, and similar median overall survival rates compared with hepatitis B virus-negative patients.

Kupffer Cells Support Hepatitis B Virus-Mediated CD8+ T Cell Exhaustion via Hepatitis B Core Antigen-TLR2 Interactions in Mice

Hepatitis B virus (HBV) persistence is a fundamental process in chronic HBV infection and a key factor in all related liver diseases; however, the mechanisms have yet to be elucidated. We studied the role of TLR2 in HBV persistence using a well-established HBV-carrier mouse model generated by hydrodynamically injecting a phospho-adeno-associated virus/HBV1.2 plasmid into mice. We found that a genetic deficiency in TLR2 improves HBV elimination, whereas activating TLR2 led to more stable HBV persistence, suggesting that TLR2 activation is critical in HBV persistence. Furthermore, we noted that TLR2 activation could inhibit CD8(+) T cell function, causing the exhaustion phenotype in HBV-carrier mice, because TLR2 deficiency might rescue CD8(+) T cell function in a cellular adoptive experiment. TLR2 expression on Kupffer cells (KCs) was upregulated in HBV-carrier mice, which accounts for HBV persistence, because the difference in anti-HBV immunity between HBV-carrier wild-type and Tlr2(-/-) mice did not exist after KC depletion. In addition, similar to TLR2 deficiency, after KC depletion, CD8(+) T cells were more efficiently activated in HBV-carrier mice, leading to rapid HBV elimination. KCs produced more IL-10 upon TLR2 activation in response to direct hepatitis B core Ag stimulation, and the elevated IL-10 inhibited CD8(+) T cell function in HBV-carrier mice, because IL-10 deficiency or anti-IL-10R treatment resulted in CD8(+) T cells with stronger antiviral function. In conclusion, KCs support liver tolerance by inducing anti-HBV CD8(+) T cell exhaustion via IL-10 production after TLR2 activation by hepatitis B core Ag stimulation.

Evaluation of Interleukin-10 Levels in Patients Diagnosed with Chronic Hepatitis

OBJECTIVE

One of the most important factors playing a role in chronic hepatitis B pathogenesis is cytokine release and one of the cytokines with anti-inflammatory characteristic is interleukin-10 (IL-10). The aim of the present study is to examine IL-10 levels in patients with chronic hepatitis B.

SUBJECTS AND METHODS

Sixty-three patients with chronic hepatitis B disease who had not received any antiviral treatment were included in the study. Serum IL-10 level was investigated by enzyme-linked immunosorbent assay (ELISA) method. In the control group, 25 healthy individuals with mean age similar to the patient population were included. Control and patient groups were compared and data were statistically analysed.

RESULTS

Interleukin-10 levels of 25 patients with hepatitis B virus (HBV) DNA levels between 2000 and 20 000 IU/mL were compared with those of 25 subjects in the control group, and the level in the chronic hepatitis B group was statistically significantly higher (p < 0.05). Interleukin-10 levels of 38 patients with HBV DNA > 20 000 IU/mL were statistically significantly higher than those in the control group. When chronic hepatitis B patients were compared among themselves, IL-10 levels increased as HBV DNA levels increased. Also, when IL-10 levels of hepatitis B 'e' antigen (HBeAg) positive patients were compared with those of HBeAg negative patients, the difference was not statistically significant.

CONCLUSION

It is believed that decreasing IL-10 levels by various methods would have significant contributions in disease progression and treatment. Moreover, IL-10 level may be an important marker in HBeAg seroconversion and evaluation of treatment response.

T cell exhaustion during persistent viral infections

Although robust and highly effective anti-viral T cells contribute to the clearance of many acute infections, viral persistence is associated with the development of functionally inferior, exhausted, T cell responses. Exhaustion develops in a step-wise and progressive manner, ranges in severity, and can culminate in the deletion of the anti-viral T cells. This disarming of the response is consequential as it compromises viral control and potentially serves to dampen immune-mediated damage. Exhausted T cells are unable to elaborate typical anti-viral effector functions. They are characterized by the sustained upregulation of inhibitory receptors and display a gene expression profile that distinguishes them from prototypic effector and memory T cell populations. In this review we discuss the properties of exhausted T cells; the virological and immunological conditions that favor their development; the cellular and molecular signals that sustain the exhausted state; and strategies for preventing and reversing exhaustion to favor viral control.

Immunopathogenesis of chronic hepatitis B

Chronic hepatitis B (CHB) is a widespread infectious disease with unfavorable outcomes and life-threatening consequences for patients, in spite of modern vaccination and antiviral treatment modalities. Cutting-edge experimental approaches have demonstrated key pathways that involve cross-talk between viral particles and host immune cells. All events, including penetration of hepatitis B virus (HBV) particles into host cells, establishing persistence, and chronization of CHB infection, and possibility of complete elimination of HBV particles are controlled by the immune system. Researchers have paid special attention to the replication capacity of HBV in host cells, which is associated with cellular changes that reflect presentation of viral antigens and variability of HBV antigen features. In addition, specific HBV proteins have an immune-modulating ability to initiate molecular mechanisms that “avoid” control by the immune system. The relationship between immunological shifts and chronic infection stages has been intensively studied since it was recognized that the immune system is a direct participant in the recurrent (cyclic) nature of CHB. Understanding the wide diversity of molecular pathways and the crosstalk between innate and adaptive immune system components will provide fresh insight into CHB immune pathogenesis and the possibilities of developing new treatment strategies for this disease.

Identification of serum cytokine profiles associated with HBeAg seroconversion following antiviral treatment interruption

The major shortcoming of nucleos(t)ide analogue therapy for chronic hepatitis B (CHB) is the frequent requirement for indefinite therapy. Withdrawal of treatment can result in viral rebound with an alanine aminotransferase (ALT) flare leading to hepatic decompensation, while in others this can lead to hepatitis B e antigen (HBeAg) seroconversion. The aim of the study was to identify host immune profiles associated with these different outcomes. Eighteen HBeAg(+) patients, enrolled on a phase III trial with the nucleoside analogue adefovir dipivoxil, were followed for up to 128 weeks. For the first 48 weeks, all patients received continuous therapy. Subsequently, patients experienced cycles of treatment interruptions due to random drug/placebo misallocations. Host immune profiles were characterized by measuring a panel of serum cytokines before, during, and after each cycle of treatment withdrawal. Virus-specific T-cell responses were also determined at these time points in a subset of patients to elucidate the mechanisms utilized to control hepatitis B virus (HBV) replication post-treatment. Significantly, elevated levels of IFN-γ, IP-10, and IL-2 on-treatment were associated with HBeAg seroconversion after treatment withdrawal. In these patients, treatment interruption induced further increases in serum IFN-γ levels and marked increases in virus-specific T-cells producing IFN-γ, but minimal alterations in viremia and ALT. In HBeAg(+) patients with low on-treatment levels of serum IFN-γ, the interruption of therapy induced significant elevations in HBV-DNA, ALT, IP-10, and increases in virus-specific T-cells producing IL-10. Evaluating on-treatment serum cytokines in concert with virologic and clinical parameters may help to identify CHB patients who can successfully discontinue nucleos(t)ide analogue therapy.

Association of interleukin-10 with hepatitis B virus (HBV) mediated disease progression in Indian population

BACKGROUND & OBJECTIVES

Interleukin (IL)-10, an anti-inflammatory Th2 cytokine, is one of the key coordinators of the inflammatory responses involved. The present study was designed to evaluate the impact of IL-10 (-819/-592) genotypes, haplotypes, mRNA and the protein levels with risk for hepatitis B virus (HBV) related hepatocellular carcinoma (HCC) development in India.

METHODS

A total of 390 subjects (145 controls, 62 inactive HBV-carriers, 64 chronic-active HBV patients, 60 HBV related cirrhotics and 59 HBV- HCC subjects) were enrolled in the study. Allele specific (AS)-PCR, ELISA and RT-PCR methods were used for assessing polymorphism, spontaneous blood levels and the mRNA expression, respectively of IL-10.

RESULTS

The study revealed that the CC/TA genotype acted as a risk factor for cirrhosis (OR a =2.02; P<0.05) and the subsequent HCC development (OR a =2.20; P<0.05), with controls as reference. However, no significant association was found between the two haplotypes (CC and TA) observed and HCC risk. Moreover, the IL-10 protein and mRNA levels in peripheral blood mono nuclear cells (PBMCs) showed a significant elevation as the disease progressed to cirrhosis. But, no variation was observed in the IL-10 levels in subjects with different IL-10 genotypes.

INTERPRETATION & CONCLUSIONS

These preliminary results suggest a strong association of IL10 (-819/-592) with the HBV infection mediated disease progression, from inactive carrier state to malignancy, in Indian population.

Fallen angels or risen apes? A tale of the intricate complexities of imbalanced immune responses in the pathogenesis and progression of immune-mediated and viral cancers

Excessive immune responses directed against foreign pathogens, self-antigens, or commensal microflora can cause cancer establishment and progression if the execution of tight immuno-regulatory mechanisms fails. On the other hand, induction of potent tumor antigen-specific immune responses together with stimulation of the innate immune system is a pre-requisite for effective anti-tumor immunity, and if suppressed by the strong immuno-regulatory mechanisms can lead to cancer progression. Therefore, it is crucial that the inevitable co-existence of these fundamental, yet conflicting roles of immune-regulatory cells is carefully streamlined as imbalances can be detrimental to the host. Infection with chronic persistent viruses is characterized by severe immune dysfunction resulting in T cell exhaustion and sometimes deletion of antigen-specific T cells. More often, this is due to increased immuno-regulatory processes, which are triggered to down-regulate immune responses and limit immunopathology. However, such heightened levels of immune disruption cause a concomitant loss of tumor immune-surveillance and create a permissive microenvironment for cancer establishment and progression, as demonstrated by increased incidences of cancer in immunosuppressed hosts. Paradoxically, while some cancers arise as a consequence of increased immuno-regulatory mechanisms that inhibit protective immune responses and impinge on tumor surveillance, other cancers arise due to impaired immuno-regulatory mechanisms and failure to limit pathogenic inflammatory responses. This intricate complexity, where immuno-regulatory cells can be beneficial in certain immune settings but detrimental in other settings underscores the need for carefully formulated interventions to equilibrate the balance between immuno-stimulatory and immuno-regulatory processes.

Innate immune responses in hepatitis B virus (HBV) infection

Hepatitis B virus (HBV) infection has a low rate of chronicity compared to HCV infection, but chronic liver inflammation can evolve to life threatening complications. Experimental data from HBV infected chimpanzees and HBV transgenic mice have indicated that cytotoxic T cells are the main cell type responsible for inhibition of viral replication, but also for hepatocyte lysis during chronic HBV infection. Their lower activation and impaired function in later stages of infection was suggested as a possible mechanism that allowed for low levels of viral replication. The lack of an interferon response in these models also indicated the importance of adaptive immunity in clearing the infection. Increased knowledge of the signalling pathways and pathogen associated molecular patterns that govern activation of innate immunity in the early stages of viral infections in general has led to a re-evaluation of the innate immune system in HBV infection. Numerous studies have shown that HBV employs active strategies to evade innate immune responses and induce immunosuppression. Some of the immune components targeted by HBV include dendritic cells, natural killer cells, T regulatory cells and signalling pathways of the interferon response. This review will present the current understanding of innate immunity in HBV infection and of the challenges associated with clearing of the HBV infection.

IL-10: achieving balance during persistent viral infection

The clearance of viral infections is reliant on the coordination and balance of inflammatory factors necessary for viral destruction and immunoregulatory mechanisms necessary to prevent host pathology. In the case of persistent viral infections, immunoregulatory pathways prevent the immune response from clearing the virus, resulting in a long-term equilibrium between host and pathogen. Consequently, negative immune regulators are being considered as a therapeutic target to treat persistent and chronic viral infections. In this review, we will highlight the current understanding of the important negative immune regulator interleukin-10 (IL-10) in persistent viral infection. Though its main role for the host is to limit immune-mediated pathology, IL-10 is a multifunctional cytokine that differentially regulates a number of different hematopoietic cell types. IL-10 has been shown to play a role in a number of infectious diseases and many viral pathogens specifically exploit the IL-10 pathway to help evade host immunity. Recent advances have demonstrated that manipulation of IL-10 signaling during persistent viral infection can alter T cell responses in vivo and that this manipulation can lead to the clearance of persistent viral infection. Furthermore, there have been crucial advances in the understanding of factors that induce IL-10. We summarize lessons learned about IL-10 in model organisms and human persistent infections and conclude with the potential use of IL-10 to treat persistent viral infections.

Anti-viral CD8 T cells and the cytokines that they love

Viral infections cause an immunological disequilibrium that provokes CD8 T cell responses. These cells play critical roles in purging acute infections, limiting persistent infections, and conferring life-long protective immunity. At every stage of the response anti-viral CD8 T cells are sensitive to signals from cytokines. Initially cytokines operate as immunological warning signs that inform of the presence of an infection, and also influence the developmental choices of the responding cells. Later during the course of the response other sets of cytokines support the survival and maintenance of the differentiated anti-viral CD8 T cells. Although many cytokines promote virus-specific CD8 T cells, other cytokines can suppress their activities and thus favor viral persistence. In this review we discuss how select cytokines act to regulate anti-viral CD8 T cells throughout the response and influence the outcome of viral infections.

HBsAg inhibits IFN-α production in plasmacytoid dendritic cells through TNF-α and IL-10 induction in monocytes

Type I Interferon (IFN) is one of the first lines of defense against viral infection. Plasmacytoid dendritic cells (pDCs) are professional IFN-α-producing cells that play an important role in the antiviral immune response. Previous studies have reported that IFN-α production is impaired in chronic hepatitis B (CHB) patients. However, the mechanisms underlying the impairment in IFN-α production are not fully understood. Here, we report that plasma-derived hepatitis B surface antigen (HBsAg) and HBsAg expressed in CHO cells can significantly inhibit toll like receptor (TLR) 9-mediated Interferon-α (IFN-α) production in peripheral blood mononuclear cells (PBMCs) from healthy donors. Further analysis indicated that monocytes participate in the inhibitory effect of HBsAg on pDCs through the secretion of TNF-α and IL-10. Furthermore, TLR9 expression on pDCs was down-regulated by TNF-α, IL-10 and HBsAg treatment. This down-regulation may partially explain the inhibition of IFN-α production in pDCs. In conclusion, we determined that HBsAg inhibited the production of IFN-α by pDCs through the induction of monocytes that secreted TNF-α and IL-10 and through the down-regulation of TLR9 expression on pDCs. These data may aid in the development of effective antiviral treatments and lead to the immune control of the viral infections.

Sex differences in the response to viral infections: TLR8 and TLR9 ligand stimulation induce higher IL10 production in males

Background

Susceptibility to viral infections as well as their severity are higher in men than in women. Heightened antiviral responses typical of women are effective for rapid virus clearance, but if excessively high or prolonged, can result in chronic/inflammatory pathologies. We investigated whether this variability could be in part attributable to differences in the response to the Toll-Like Receptors (TLR) more involved in the virus recognition.

Methods

Cytokine production by peripheral blood mononuclear cells (PBMCs) from male and female healthy donors after stimulation with Toll-like receptors (TLR) 3, 7, 8, 9 ligands or with viruses (influenza and Herpes-simplex-1) was evaluated.

Results

Compared to females, PBMCs from males produced not only lower amounts of IFN-α in response to TLR7 ligands but also higher amounts of the immunosuppressive cytokine IL10 after stimulation with TLR8 and TLR9 ligands or viruses. IL10 production after TLR9 ligands or HSV-1 stimulation was significantly related with plasma levels of sex hormones in both groups, whereas no correlation was found in cytokines produced following TLR7 and TLR8 stimulation.

Conclusions

Given the role of an early production of IL10 by cells of innate immunity in modulating innate and adaptive immune response to viruses, we suggest that sex-related difference in its production following viral nucleic acid stimulation of TLRs may be involved in the sex-related variability in response to viral infections.

Serum cytokine levels in patients with chronic hepatitis B according to lamivudine therapy

BACKGROUND

Cytokines are known to play critical roles in the pathogenesis of chronic hepatitis B (CHB). However, the relationship between cytokines and treatment responses to drugs for CHB is not clearly defined yet. We measured the serum cytokine levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor, interferon-γ, tumor necrosis factor- (TNF-α), macrophage/monocyte chemotactic protein 1, and epidermal growth factor to elucidate the cytokine expression pattern according to the patients' responses to lamivudine.

METHODS

Fifty-eight specimens from 27 CHB patients and 98 specimens from healthy individuals were tested for 12 kinds of cytokines. The patients were grouped as: before treatment, ongoing treatment, duringmaintaining remission, and patients with viral breakthrough owing to resistance against lamivudine. The Evidence Investigator (Randox, Antrim, UK), a protein chip analyzer, was used to quantify serum cytokines.

RESULTS

Among 12 cytokines, IL-6, IL-8, IL-10, and TNF-α were significantly elevated in patients with resistance against lamivudine compared with patients maintaining response. IL-8, IL-10, and TNF-α levels also weak to moderate correlated with ALT and HBV-DNA concentrations.

CONCLUSIONS

Serum cytokine levels would reflect the pathological differences of the individual treatment phases and may become useful indices in monitoring the treatment response of CHB.

A study of circulating interleukin 10 in prognostication of unresectable hepatocellular carcinoma

BACKGROUND

The level of circulating interleukin 10 (IL-10) is elevated in a proportion of patients with hepatocellular carcinoma (HCC). The objective of the current study was to evaluate the prognostic significance of serum the IL-10 level in patients with unresectable HCC.

METHODS

Patients with unresectable HCC who provided serum at the time of diagnosis were enrolled prospectively in the study. The level of circulating IL-10 in serum samples was determined by enzyme-linked immunosorbent assay. The association of the IL-10 level with overall survival was evaluated in relation to sociodemographics, liver function, hepatitis B viral load, and tumor staging.

RESULTS

In total, 222 patients were recruited; of these, 82.4% were positive for hepatitis B virus surface antigen, and 65.8% had Barcelona Clinic Liver Cancer stage C disease. The mean log IL-10 level was 1.1 pg/mL, and 146 patients had an IL-10 level >1 pg/mL (high IL-10 group). The high IL-10 group had worse overall survival than the low IL-10 group (5.0 months vs 14.9 months; hazard ratio, 2.192; P < .0001). The IL-10 level was associated with worse hepatic function and with a high alanine transaminase (ALT) level. The IL-10 level remained an independent prognostic factor (hazard ratio, 1.824; P = .0005) after adjustment for sociodemographics, tumor staging, treatment, Child-Pugh stage, and ALT level. The IL-10 level also subdivided patients into 2 populations with distinct survival (10.2 months vs 3.5 months; P = .0027).

CONCLUSIONS

The serum IL-10 level was identified as an independent prognostic factor for unresectable HCC. The current findings suggested that an elevated IL-10 level may be related to hepatic injury caused by cirrhotic processes rather than tumor load. The authors concluded that the IL-10 level offers additional prognostic value to the existing tumor staging systems.

Mechanism of T cell exhaustion in a chronic environment

T cell exhaustion develops under conditions of antigen-persistence caused by infection with various chronic pathogens, such as human immunodeficiency virus (HIV) and mycobacterium tuberculosis (TB), or by the development of cancer. T cell exhaustion is characterized by stepwise and progressive loss of T cell function, which is probably the main reason for the failed immunological control of chronic pathogens and cancers. Recent observations have detailed some of the intrinsic and extrinsic factors that influence the severity of T cell exhaustion. Duration and magnitude of antigenic activation of T cells might be associated with up-regulation of inhibitory receptors, which is a major intrinsic factor of T cell exhaustion. Extrinsic factors might include the production of suppressive cytokines, T cell priming by either non-professional antigen-presenting cells (APCs) or tolerogenic dendritic cells (DCs), and alteration of regulatory T (Treg) cells. Further investigation of the cellular and molecular processes behind the development of T cell exhaustion can reveal therapeutic targets and strategies for the treatment of chronic infections and cancers. Here, we report the properties and the mechanisms of T cell exhaustion in a chronic environment.

Cowpox virus induces interleukin-10 both in vitro and in vivo

Cowpox virus infection induces interleukin-10 (IL-10) production from mouse bone marrow-derived dendritic cells (BMDCs) or cells of the mouse macrophage line (RAW264.7) at about 1800 pg/ml, whereas infections with vaccinia virus (strains WR or MVA) induced much less IL-10. Similarly, in vivo, IL-10 levels in bronchoalveolar lavage fluids of mice infected with cowpox virus were significantly higher than those after vaccinia virus infection. However, after intranasal cowpox virus infection, although dendritic and T-cell accumulations in the lungs of IL-10 deficient mice were greater than those in wild-type mice, weight-loss and viral burdens were not significantly different. IL-10 deficient mice were more susceptible than wild-type mice to re-infection with cowpox virus even though titers of neutralizing antibodies and virus-specific CD8 T cells were similar between IL-10 deficient and wild-type mice. Greater bronchopneumonia in IL-10 deficient mice than wild-type mice suggests that IL-10 contributes to the suppression of immunopathology in the lungs.

Regulatory T cells in HBV and HCV liver diseases: implication of regulatory T lymphocytes in the control of immune response

IMPORTANCE OF THE FIELD

Hepatic cirrhosis is a frequent consequence of chronic hepatitis infection (HBV and HCV) or alcohol abuse and the most common cause of hepatocellular carcinoma (HCC). Currently, liver transplantation remains the only effective therapeutic approach for cirrhosis-related HCC patients. The evolution of the pathology strongly depends on immunological mechanisms.

AREAS COVERED IN THIS REVIEW

Despite the presence of specific T cells, viral chronic infection and continuous tumor growth suggest a failure of immune control. It appears that direct suppression of antiviral or antitumor effector cells by regulatory T cells plays a pivotal role in the impairment of immune response. Several types of regulatory T cells have been described, natural regulatory T cells (nTreg) and induced-type 1 regulatory T cells (Tr1) being the best characterized.

WHAT THE READER WILL GAIN

Currently, there is no evidence for a direct implication of regulatory T cells in the evolution of hepatitis, especially concerning chronic infection, cirrhosis late stage and HCC progress. However, recent studies show that regulatory T cells are implicated in the modulation of HBV- and HCV-associated immune response, thus, promoting HCC progress.

TAKE HOME MESSAGE

Therefore, nTreg and Tr1 cells seem to play an important role in the control of immune response leading to chronic hepatitis infection and progression of the pathology to cirrhosis and HCC.

Hepatitis B immunology for clinicians

Hepatitis B virus (HBV) is a hepatotrophic DNA virus that causes acute and chronic hepatitis. Despite an effective vaccine, more than 350 million people are chronically infected with HBV worldwide and are at risk for progressive liver disease. There are marked geographic variations in HBV prevalence (ranging from 0.1% to 2% in low prevalence areas and 10% to 20% in high prevalence areas) related to the timing and mode of HBV exposure. In many developed countries, HBV exposure typically occurs in adults via sexual transmission with a low chronicity rate (5%). In regions with high HBV prevalence (eg, Asia, sub-Saharan Africa), HBV exposure tends to occur in the perinatal period (eg, vertical transmission from mother to infant) with a high rate of persistence in the absence of timely vaccination. The course of viral infection is defined by the interplay between the virus and host immune defense. This article introduces the innate and adaptive immune defense mechanisms in general and as related to HBV. In particular, the current concepts regarding the innate and adaptive immune components contributing to the clinical, virologic and therapeutic outcome in acute and chronic hepatitis B are examined.

Association of cytokine genetic polymorphisms with the humoral immune response to recombinant vaccine against HBV in infants

The prevention of hepatitis B by vaccination is one the most efficient tools to avoid the transmission of the virus, although a considerable variability to the anti-HBsAg antibody response has been described. Recently, polymorphisms of cytokine regulating genes have been described which seem to influence the immune response to various antigens. This article's objective was to evaluate the influence of cytokine genetic polymorphisms onto the humoral immune response to hepatitis B vaccine in infants. Vaccinated children were classified according to the level of anti-HBsAg antibody titles. The genotyping for TNF (-308), TGFB1 (+869, +915), IL-10 (-1082, -819, -592), IL-6 (-174), and IFNG (+874) was accomplished by the PCR-SSP technique. The TNF (-308) allele A presented a lower but not statistically significant frequency at 5% level in high responder patients (3.7% vs. 12.3%, P = 0.0919). The same was seen for the TNF (-308) genotype GA (7.4% vs. 24.5%, P = 0.0757). Further studies in other populations and evaluation of a greater number of individuals may contribute for a better understanding of the cytokine gene polymorphism influence in general and TNF polymorphism more specifically in the humoral immune response to the HBsAg vaccination in newborn children.

Immunity and immunopathology to viruses: what decides the outcome?

Many viruses infect humans and most are controlled satisfactorily by the immune system with limited damage to host tissues. Some viruses, however, do cause overt damage to the host, either in isolated cases or as a reaction that commonly occurs after infection. The outcome is influenced by properties of the infecting virus, the circumstances of infection and several factors controlled by the host. In this Review, we focus on host factors that influence the outcome of viral infection, including genetic susceptibility, the age of the host when infected, the dose and route of infection, the induction of anti-inflammatory cells and proteins, as well as the presence of concurrent infections and past exposure to cross-reactive agents.

HBcAg induces interleukin-10 production, inhibiting HBcAg-specific Th17 responses in chronic hepatitis B patients

T-helper (Th) 17 cells have been shown to have an important role in host defense against viral infection. However, little is known about the regulation of Th17 cells in hepatitis B virus (HBV) infections. Peripheral blood mononuclear cells (PBMCs) isolated from patients with chronic hepatitis B (CHB) were stimulated with anti-interleukin (IL)-10 antibody or recombinant IL-10. The frequency of hepatitis B core antigen (HBcAg)-specific Th17 cells was characterized and produced cytokines were determined by flow cytometry. A low frequency of Th17 cells and a high frequency of Th1 cells were detected in CHB patients. HBcAg stimulation promoted IL-17A, IL-22, IL-23, IL-6, transforming growth factor (TGF)-β and IL-10 production by PBMCs from CHB patients, but not from healthy controls. Furthermore, endogenous IL-10 inhibited HBcAg-stimulated production of IL-17A, IL-22, IL-6 and IL-23, but not TGF-β. Treatment with IL-10 inhibited the HBcAg-stimulated activation of Th17 cells, whereas anti-IL-10 antibody significantly increased the frequency of Th17 and Th1 cells, but not that of CD4(+)CD25(+) regulatory T cells, associated with upregulating RORγt expression in CD4(+) T cells. HBcAg stimulated the production of IL-10, which negatively regulated HBcAg-specific Th17 cell responses in CHB patients. Our findings may represent one evasion strategy for HBV to subvert specific antiviral responses in humans.

T-cell exhaustion: characteristics, causes and conversion

T-cell exhaustion is characterized by the stepwise and progressive loss of T-cell functions and can culminate in the physical deletion of the responding cells. Exhaustion is well-defined during chronic lymphocytic choriomeningitis virus infection and commonly develops under conditions of antigen-persistence, which occur following many chronic infections that are of significant public health concern including hepatitis B virus, hepatitis C virus and human immunodeficiency virus infections, as well as during tumour outgrowth. Exhaustion is not a uniformly disabled setting as a gradation of phenotypic and functional defects can manifest, and these cells are distinct from prototypic effector, memory and also anergic T cells. We are gaining insights into the extrinsic and intrinsic factors that determine the severity of exhaustion. These include the duration and magnitude of antigenic activation, availability of CD4 T-cell help, the levels of stimulatory and suppressive cytokines, as well as the expression of activatory and inhibitory receptors. More information is now becoming available regarding the molecular mechanisms that attenuate the responsiveness of exhausted T cells. As the parameters that dictate exhaustion are more thoroughly defined, this is fostering the development of methods that prevent and rejuvenate functionally inferior responses. In this article we discuss our current understanding of the properties of exhausted T cells and the mechanisms that promote and maintain this state.

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.

Altered T cell costimulation during chronic hepatitis B infection

T-cell response to hepatitis B virus (HBV) is vigorous, polyclonal and multi-specific in patients with acute hepatitis who ultimately clear the virus, whereas it is narrow and inefficient in patients with chronic disease, where inappropriate early activation events could account for viral persistence. We investigated the induction of activation receptors and cytokine production in response to HBcAg and crosslinking of CD28 molecules, in CD4+ cells from a group of chronically infected patients (CIP) and naturally immune subjects (NIS). We demonstrated that CD4+ cells from CIP did not increase levels of CD40L and CD69 following stimulation with HBcAg alone or associated to CD28 crosslinking, in contrast to subjects that resolved the infection (p<0.01). Furthermore, CD4+ cells from CIP produced elevated levels of IL-10 in response to HBcAg. These results suggest that a predominant inhibitory environment may be responsible for altered T cell costimulation, representing a pathogenic mechanism for viral persistence.

Hepatitis B virus-induced hFGL2 transcription is dependent on c-Ets-2 and MAPK signal pathway

Fibrinogen-like protein 2 (FGL2)/fibroleukin plays a pivotal role in the pathogenesis of experimental and human fulminant and chronic viral hepatitis. To define the transcription factor(s) and upstream signal transduction pathways involved in the transcription of human FGL2 (hFGL2) in response to hepatitis B (HB) virus, hepatitis B core (HBc), hepatitis B virus S protein (HBs), or hepatitis B virus X protein (HBx) protein, expression plasmids were cotransfected with an hFGL2 promoter luciferase reporter construct into Chinese hamster ovary and HepG2 cells, respectively. HBc and HBx proteins, but not HBs protein, enhanced hFGL2 transcription in both cell lines. A strong regulatory region from -712 to -568 (relative to the transcriptional starting site) was shown to be responsible for hFGL2 gene transcription in response to both HBc and HBx proteins. c-Ets-2 was shown to be translocated to the nucleus in association with hFGL2 expression in response to both HBc and HBx proteins. Short hairpin RNA (shRNA) interference of c-Ets-2 expression inhibited hFGL2 gene transcription by 64.8 and 60.0% in response to HBc and HBx, respectively. c-Ets-2 protein was highly expressed in peripheral blood mononuclear cells from patients with severe chronic hepatitis B (CHB) in contrast to patients with mild CHB. Increased phosphorylation of ERK and JNK was detected in peripheral blood mononuclear cells from patients with severe CHB. ERK inhibitor PD098059 or ERK shRNA abolished the nuclear c-Ets-2 DNA binding activity and hFGL2 induction in response to HBc, whereas JNK inhibitor SP600125 or JNK shRNA abolished the nuclear c-Ets-2 DNA binding activity and hFGL2 induction in response to HBx. In conclusion, HBc and HBx proteins enhance transcription of hFGL2 through c-Ets-2 dependent on MAPK signal pathways.

Association of cytokine genetic polymorphism with hepatitis B infection evolution in adult patients

The infection by the hepatitis B virus (HBV) has different forms of evolution, ranging from self-limited infection to chronic hepatic disease. The objective of this study was to evaluate the influence of cytokine genetic polymorphisms in the disease evolution. The patients were divided into two groups, one with chronic HBV (n = 30), and the other with self-limited infection (n = 41). The genotyping for TNF (-308), TGFB1 (+869, +915), IL-10 (1082, -819, and -592), IL-6 (-174), and IFNG (+874) was accomplished by the PCR-SSP (polymerase chain reaction with sequence specific primers technique using the One Lambda kit. Although no statistically significant differences were found between the groups, the combination of TNF -308GG and IFNG +874TA was found in a lower frequency in chronic patients than in individuals with self-limited infection (26.7 versus 46.3%; P = 0.079; OR = 0.40; IC95% = 0.14-1.11). In chronic patients with histological alterations it was not observed the genotype TGFB1+869 C/C, against 24.4% in the self limited infection group (100 versus 75.6%; P = 0.096; OR = 7.67; IC95% = 0.42-141.63). Further studies in other populations, and evaluation of a greater number of individuals could contribute for a better understanding of the cytokine genetic polymorphism influence in HBV infection evolution.

Immune response and tolerance during chronic hepatitis B virus infection

The hepatitis B virus (HBV) is a hepatotropic non-cytopathic DNA virus that despite the presence of an effective prophylactic vaccine is estimated to infect 300 million people, with a particularly high prevalence in Asia and Africa. It causes liver diseases that vary greatly in severity from person to person. Some subjects control infection efficiently and clear the virus from the bloodstream either without clinically evident liver disease or with an acute inflammation of the liver (acute hepatitis) that can resolve without long-term clinical sequelae. Other patients fail to clear the virus and develop chronic infection. Most chronically infected patients remain asymptomatic without life-threatening liver disease but 10-30% develop liver cirrhosis with possible progression to liver cancer. Outcome of infection and the pathogenesis of liver disease are determined by virus and host factors, which have been difficult tofully elucidate because the host range of HBV is limited to man and chimpanzees. However, the study of animal models of related Hepadnavirus infections and transgenic mouse able to express individual HBV genes or replicate the entire viral genome have clarified several aspects connected to HBV infection. Furthermore, the ability to analyze many immunological phenomena ex vivo through direct quantification of Ag-specific T cells in humans and chimps has considerably increased our knowledge of HBV pathogenesis. Here, we will discuss the distinctions of HBV adaptive immunity between resolved and persistently infected patients and the host/viral factors that can cause and maintain them.

Hepatitis B virus (HBV) antigen-pulsed monocyte-derived dendritic cells from HBV-associated hepatocellular carcinoma patients significantly enhance specific T cell responses in vitro

To investigate whether hepatitis B virus (HBV) antigen-pulsed monocyte-derived dendritic cells (MoDC) could mount a T cell response in hepatocellular carcinoma (HCC) patients associated with chronic HBV infection, peripheral blood mononuclear cells (PBMCs) from 36 HBV-associated HCC patients were induced into MoDC and pulsed with hepatitis B core antigen (HBcAg) and hepatitis B surface antigen (HBsAg), alone and in combination. Co-stimulatory molecules CD80, CD86 and CD40, as well as human leucocyte antigens D-related (HLA-DR) were found to express at the highest level on MoDC pulsed with HBcAg or HBsAg + HBcAg, at a median level on MoDC pulsed with HBcAg or HBsAg alone, and at the lowest level on non-antigen-pulsed MoDC. Interleukin (IL)-10 and IL-12 cytokines were released by antigen-pulsed MoDC at increased levels in the order: no-antigen < HBsAg < HBcAg < HBcAg + HBsAg. MoDC pulsed with HBcAg or HBsAg + HBcAg also had the strongest ability to stimulate autologous T cell proliferation and intracellular interferon (IFN)-gamma production. HBcAg- or HBsAg + HBcAg-pulsed MoDC could also induce HBV core peptide-specific CD8(+) T cell proliferation determined by tetramer staining. In addition, the antigen-pulsed MoDC were found to have a stronger capacity to produce IL-12 and induce T cell response in vitro for patients with higher alanine transaminase (ALT) levels than those with lower ALT levels, indicating that antigen pulse could substantially reverse the impaired function of MoDC in primary HCC patients with active chronic hepatitis B. In conclusion, HBV antigen-pulsed MoDC from HCC patients with chronic hepatitis B could induce HBV-specific T cell response in vitro.