Monocytes from chronic HBV patients react in vitro to HBsAg and TLR by producing cytokines irrespective of stage of disease

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.

Monocyte Transcriptome in Different Phases of Chronic Hepatitis B Virus Infection Uncovers Potential Functional Roles

The hepatitis B virus (HBV) chronic infection goes through different phases, i.e., immune tolerant (IT), immune clearance (IC), and inactive carrier (IN) resulting from the interplay of viral replication and immune response. Although the adaptive immune response is central to viral control, roles of the innate immune cells are less prominent. We explored monocyte transcriptome in these different phases of HBV infection to understand the nature of its involvement and identify unique differentially expressed genes (DEGs) in each phase. CD14+ peripheral blood monocytes were isolated from patients in the IT, IC, and IN phases and from healthy subjects and their RNA was sequenced. The significant DEGs were studied through gene annotation databases to understand differentially modulated pathways. The DEGs were further validated by qRT-PCR to identify genes that were uniquely expressed in each phase. It was found that TNFRSF12A was upregulated in all the HBV samples. The IN phase had six uniquely upregulated genes, i.e., PI3, EMP1, STX1A, RRAD, SPINK1, and SNORD3B-2. E2F7 was most consistently downregulated in the IT phase, and in the IC phase, IL23A and PI3 were specifically downregulated. Cut-off values were generated by ROC curve analysis to differentiate between the groups based on their expression levels. The monocyte functions are majorly suppressed in the IT and IC phases and are, however, somewhat metabolically active in the IN phase.

Overview of miR-106a Regulatory Roles: from Cancer to Aging

MicroRNAs (miRNAs) comprise a class of non-coding RNA with extensive regulatory functions within cells. MiR-106a is recognized for its super-regulatory roles in vital processes. Hence, the analysis of its expression in association with diseases has attracted considerable attention for molecular diagnosis and drug development. Numerous studies have investigated miR-106 target genes and shown that this miRNA regulates the expression of some critical cell cycle and apoptosis factors, suggesting miR-106a as an ideal diagnostic and prognostic biomarker with therapeutic potential. Furthermore, the reported correlation between miR-106a expression level and cancer drug resistance has demonstrated the complexity of its functions within different tissues. In this study, we have conducted a comprehensive review on the expression levels of miR-106a in various cancers and other diseases, emphasizing its target genes. The promising findings surrounding miR-106a suggest its potential as a valuable biomolecule. However, further validation assessments and overcoming existing limitations are crucial steps before its clinical implementation can be realized.

The Human Male Liver Is Predisposed to Inflammation Via Enhanced Myeloid Responses to Inflammatory Triggers

Background & Aim

Men have a higher prevalence of liver disease. Liver myeloid cells can regulate tissue inflammation, which drives progression of liver disease. We hypothesized that sex alters the responsiveness of liver myeloid cells, predisposing men to severe liver inflammation.

Methods

Luminex was done on plasma from Hepatitis B Virus infected patients undergoing nucleoside analogue cessation in 45 male and female patients. We collected immune cells from the sinusoids of uninfected livers of 53 male and female donors. Multiparametric flow cytometry was used to phenotype and characterize immune composition. Isolated monocytes were stimulated with TLR ligands to measure the inflammatory potential and the expression of regulators of TLR signaling.

Results

We confirmed that men experienced more frequent and severe liver damage upon Hepatitis B Virus reactivation, which was associated with inflammatory markers of myeloid activation. No differences were observed in the frequency or phenotype of sinusoidal myeloid cells between male and female livers. However, monocytes from male livers produced more inflammatory cytokines and chemokines in response to TLR stimulation than female monocytes. We investigated negative regulators of TLR signaling and found that TOLLIP was elevated in female liver-derived monocytes

Conclusions

Our data show that enhanced responsiveness of myeloid cells from the male liver predisposes men to inflammation, which was associated with altered expression of negative regulators of TLR signaling.

Follicular Helper T (TFH) Cell Targeting by TLR8 Signaling For Improving HBsAg-Specific B Cell Response In Chronic Hepatitis B Patients

Identifying signaling pathways that induce B cell response can aid functional cure strategies for chronic hepatitis B infection (CHB). TLR8 activation with ssRNA was shown to enhance follicular helper T cell (T_FH) function leading to improved B cell responses in vitro. We investigated whether this mechanism can rescue an exhausted immune response in CHB infection. Effect of TLR8 agonism on supporting cytokines and T_FH and B cells were evaluated using ex vivo and in vitro assays. The ability of an oral TLR8 agonist to promote T_FH and B cell response was tested in samples from phase 1b clinical trial. TLR8 agonism induced T_FH polarizing cytokine IL-12 in monocytes. Treatment of peripheral blood mononuclear cells (PBMCs) from CHB patients with TLR8 agonists induced cytokine IL-21 by T_FH cells with enhanced IL-21⁺BCL-6⁺ and ICOS⁺BCL-6⁺ co-expression. Mechanistically, incubation of isolated naïve CD4⁺ T cells with TLR8 triggered monocytes resulted in their differentiation into IL-21⁺ICOS⁺BCL-6⁺ T_FH in an IL-12 dependent manner. Furthermore, co-culture of these IL-21 producing T_FH with autologous naïve B cells led to enhanced memory (CD19⁺CD27⁺) and plasma B cell generation (CD19⁺CD27⁺⁺CD38⁺) and IgG production. Importantly, in T_FH from CHB patients treated with an oral TLR8 agonist, HBsAg-specific BCL-6, ICOS, IL-21 and CD40L expression and rescue of defective activation induced marker (AIM) response along with partial restoration of HBsAg-specific B cell ELISPOT response was evident. TLR8 agonism can thus enhance HBV-specific B cell responses in CHB patients by improving monocyte-mediated T_FH function and may play a role in achieving HBV functional cure.

Monocyte dysregulation: consequences for hepatic infections

Liver disorders due to infections are a substantial health concern in underdeveloped and industrialized countries. This includes not only hepatotropic viruses (e.g., hepatitis B, hepatitis C) but also bacterial and parasitic infections such as amebiasis, leishmaniasis, schistosomiasis, or echinococcosis. Recent studies of the immune mechanisms underlying liver disease show that monocytes play an essential role in determining patient outcomes. Monocytes are derived from the mononuclear phagocyte lineage in the bone marrow and are present in nearly all tissues of the body; these cells function as part of the early innate immune response that reacts to challenge by external pathogens. Due to their special ability to develop into tissue macrophages and dendritic cells and to change from an inflammatory to an anti-inflammatory phenotype, monocytes play a pivotal role in infectious and non-infectious liver diseases: they can maintain inflammation and support resolution of inflammation. Therefore, tight regulation of monocyte recruitment and termination of monocyte-driven immune responses in the liver is prerequisite to appropriate healing of organ damage. In this review, we discuss monocyte-dependent immune mechanisms underlying hepatic infectious disorders. Better understanding of these immune mechanisms may lead to development of new interventions to treat acute liver disease and prevent progression to organ failure.

Mechanisms of HBV immune evasion

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

High CD163 Expression on Classical Monocytes Is Associated with Immune Control of HBV Infection in Noncirrhotic Patients

Background and Aims. The functional impairment of monocytes may contribute to the persistence of HBV infection. This study aims to assess monocyte subpopulations, monocyte expression of CD163, plasma sCD163, and sTWEAK in patients with chronic HBeAg-negative HBV infection at different phases of disease. Methods. Fifty-nine patients with CHB, 9 with a history of HBsAg/anti-HBs seroconversion, were enrolled. The control group consisted of 15 healthy volunteers. Subpopulations of peripheral blood monocytes were distinguished by CD14 and CD16. Membrane expression of CD163 was assessed by flow cytometry, plasma sCD163 concentration by ELISA, and sTWEAK by bead-based multiplexed immunoassay system. Results. CD163 expression was increased in classical and intermediate monocytes in CHB patients and those with HBsAg/anti-HBs seroconversion. CD163 expression on classical monocytes was associated with status of immune control and thus significant in HBV infection as compared to active hepatitis. Plasma sCD163 concentration was increased in CHB patients and those with HBsAg/anti-HBs seroconversion vs. the control group. Positive correlations between plasma sCD163 and ALT, as well as APRI, were observed. Plasma sTWEAK concentration was lower in CHB patients in comparison to patients with HBsAg/anti-HBs seroconversion. Conclusions. Exposure to HBV antigens alters monocyte subsets’ frequencies and activation. The expression of CD163 on classical monocytes increased in parallel with improved immune control of the HBV infection. Patients who seroconverted HBsAg had the highest expression of CD163 on monocytes, which suggests involvement of monocytes in immune control of HBV infection. Persistent inflammation is accompanied by higher CD163 expression and sCD163 level and lower sTWEAK level.

Hepatitis B Virus Molecular Epidemiology, Host-Virus Interaction, Coinfection, and Laboratory Diagnosis in the MENA Region: An Update

Hepatitis B virus (HBV) is an enveloped partial double-stranded DNA virus that can cause acute and chronic hepatitis. According to the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC), 257 million people are living with HBV. Moreover, 20,900 acute hepatitis B cases were reported in 2016. Hepatitis B is highly prevalent in the African, Western Pacific, Eastern Mediterranean, South-East Asia, and European regions, respectively. Due to the high mutational rate of HBV and lack of reverse transcriptase proofreading activity, ten different genotypes with different geographical distributions have been identified. HBV pathogenesis and severity of infection depend on several host and viral factors, particularly, the genetic variability of both the host and virus. Although HBV infection is a global health concern, there is a lack of adequate studies and reports in the Middle East and North Africa (MENA) region. Here, we provide a review on HBV epidemiology, pathogenesis, host-pathogen interactions, coinfection with selected viruses, and laboratory diagnosis, focusing on studies conducted in the MENA region to determine the current situation of the HBV infection and outline the future study areas.

Hepatitis B Virus-Induced Imbalance of Inflammatory and Antiviral Signaling by Differential Phosphorylation of STAT1 in Human Monocytes

It is not clear how hepatitis B virus (HBV) modulates host immunity during chronic infection. In addition to the key mediators of inflammatory response in viral infection, monocytes also express a high-level IFN-stimulated gene, CH25H, upon response to IFN-α exerting an antiviral effect. In this study, the mechanism by which HBV manipulates IFN signaling in human monocytes was investigated. We observed that monocytes from chronic hepatitis B patients express lower levels of IFN signaling/stimulated genes and higher levels of inflammatory cytokines compared with healthy donors. HBV induces monocyte production of inflammatory cytokines via TLR2/MyD88/NF-κB signaling and STAT1-Ser727 phosphorylation and inhibits IFN-α-induced stat1, stat2, and ch25h expression through the inhibition of STAT1-Tyr701 phosphorylation and in an IL-10-dependent, partially autocrine manner. Further, we found that enhancement of STAT1 activity with a small molecule (2-NP) rescued HBV-mediated inhibition of IFN signaling and counteracted the induction of inflammatory cytokines. In conclusion, HBV contributes to the monocyte inflammatory response but inhibits their IFN-α/β responsiveness to impair antiviral innate immunity. These effects are mediated via differential phosphorylation of Tyr701 and Ser727 of STAT1.

Regulatory NK cells mediated between immunosuppressive monocytes and dysfunctional T cells in chronic HBV infection

BACKGROUND AND AIMS

HBV infection represents a major health problem worldwide, but the immunological mechanisms by which HBV causes chronic persistent infection remain only partly understood. Recently, cell subsets with suppressive features have been recognised among monocytes and natural killer (NK) cells. Here we examine the effects of HBV on monocytes and NK cells.

METHODS

Monocytes and NK cells derived from chronic HBV-infected patients and healthy controls were purified and characterised for phenotype, gene expression and cytokines secretion by flow cytometry, quantitative real-time (qRT)-PCR, ELISA and western blotting. Culture and coculture of monocytes and NK cells were used to determine NK cell activation, using intracellular cytokines staining.

RESULTS

In chronic HBV infection, monocytes express higher levels of PD-L1, HLA-E, interleukin (IL)-10 and TGF-β, and NK cells express higher levels of PD-1, CD94 and IL-10, compared with healthy individuals. HBV employs hepatitis B surface antigen (HBsAg) to induce suppressive monocytes with HLA-E, PD-L1, IL-10 and TGF-β expression via the MyD88/NFκB signalling pathway. HBV-treated monocytes induce NK cells to produce IL-10, via PD-L1 and HLA-E signals. Such NK cells inhibit autologous T cell activation.

CONCLUSIONS

Our findings reveal an immunosuppressive cascade, in which HBV generates suppressive monocytes, which initiate regulatory NK cells differentiation resulting in T cell inhibition.

Hepatitis B Virus Blocks the CRE/CREB Complex and Prevents TLR9 Transcription and Function in Human B Cells

Effective B cell responses such as cytokine secretion, proliferation, and Ab-specific responses are essential to clear hepatitis B virus (HBV) infection. However, HBV alters numerous immune pathways to persist in the host. B cell activity depends on activation of the innate sensor TLR9 by viral or bacterial DNA motifs. How HBV can deregulate B cell functions remains unknown. In this study, we show that HBV can enter and decrease TLR9 expression in human primary B cells. Using PBMCs from human blood donors, we show that TLR9 expression was reduced in all peripheral B cells subsets exposed to HBV. B cell function mediated by TLR9, but not TLR7, such as proliferation and proinflammatory cytokines secretion, were abrogated in the presence of HBV; however, global Ig secretion was not downregulated. Mechanistically, we show, using human myeloma B cell line RPMI 8226, that the surface Ag hepatitis B surface Ag was responsible for TLR9 dysfunction. hepatitis B surface Ag suppressed the phosphorylation and thus the activation of the transcription factor CREB, preventing TLR9 promoter activity. Finally, we corroborated our in vitro findings in a cohort of chronic HBV carriers and found that TLR9 expression and function were significantly suppressed. The effect of HBV on TLR9 activity in B cells gives insights into oncoviral immune escape strategies, providing knowledge to develop novel immunotherapeutic approaches in chronic HBV-carrier patients.

Interplay between the Hepatitis B Virus and Innate Immunity: From an Understanding to the Development of Therapeutic Concepts

The hepatitis B virus (HBV) infects hepatocytes, which are the main cell type composing a human liver. However, the liver is enriched with immune cells, particularly innate cells (e.g., myeloid cells, natural killer and natural killer T-cells (NK/NKT), dendritic cells (DCs)), in resting condition. Hence, the study of the interaction between HBV and innate immune cells is instrumental to: (1) better understand the conditions of establishment and maintenance of HBV infections in this secondary lymphoid organ; (2) define the role of these innate immune cells in treatment failure and pathogenesis; and (3) design novel immune-therapeutic concepts based on the activation/restoration of innate cell functions and/or innate effectors. This review will summarize and discuss the current knowledge we have on this interplay between HBV and liver innate immunity.

Hepatitis B Virus e Antigen Regulates Monocyte Function and Promotes B Lymphocyte Activation

Hepatitis B virus (HBV) e (HBe) antigen is a nonstructural virus component with great immune regulation roles. It regulates adaptive immunity response and participates in persistent infection development. However, its roles on monocytes and B lymphocytes were rarely studied. Herein, we studied HBe roles on U937 and Hmy2.CIR by creating HBe stably transfected cells using lentivirus. We detected the motility of HBe-U937 through transwell migration assay. Cytokines that primarily produced by monocytes, including BAFF, B-cell activating factor (BAFF), interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and A proliferation inducing ligand (APRIL), were measured in culture supernatants of transfected U937, and serum BAFF, IL-6, and IL-10 were detected in HBe-positive and HBe-negative HBV-infected patients. Among these, BAFF mRNA and membrane-bound BAFF were further detected. Activation and inhibition markers of B lymphocytes on HBe-Hmy2.CIR and proliferation of transfected Hmy2.CIR after coculture with transfected U937 were also detected. We found that U937 migration was inhibited by HBe. BAFF expression was increased in HBe-U937, however, membrane-bound BAFF on HBe-U937 was decreased. In addition, Serum BAFF in HBe-positive patients was higher than in HBe-negative patients. IL-6 and IL-10 were increased in HBe-U937 after being stimulated by lipopolysaccharide (LPS), however, serum IL-6 and IL-10 were not associated with HBe status in patients. Besides, TNF-α and APRIL expression were basically the same in GV166-U937 and HBe-U937. B lymphocyte activation markers CD86 and Tspan33 were raised in HBe-Hmy2.CIR. However, inhibition markers Lyn and CD32b had no differences between HBe-Hmy2.CIR and control. Proliferation of transfected Hmy2.CIR was not affected by coculture with transfected U937, however, HBe transfection itself enhanced Hmy2.CIR proliferation. Altogether, these revealed that HBe can inhibit U937 migration and promote cytokines, including BAFF, IL-6, and IL-10, production in U937. Besides, HBe enhances BAFF release from U937 and increases BAFF concentration in vivo. In addition, HBe antigen facilitates Hmy2.CIR activation and proliferation through direct induction.

Liver Monocytes and Kupffer Cells Remain Transcriptionally Distinct during Chronic Viral Infection

Due to the scarcity of immunocompetent animal models for chronic viral hepatitis, little is known about the role of the innate intrahepatic immune system during viral replication in the liver. These insights are however fundamental for the understanding of the inappropriate adaptive immune responses during the chronic phase of the infection. We apply the Lymphocytic Choriomenigitis Virus (LCMV) clone 13 mouse model to examine chronic virus-host interactions of Kupffer cells (KC) and infiltrating monocytes (IM) in an infected liver. LCMV infection induced overt clinical hepatitis, with rise in ALT and serum cytokines, and increased intrahepatic F4/80 expression. Despite ongoing viral replication, whole liver transcriptome showed baseline expression levels of inflammatory cytokines, interferons, and interferon induced genes during the chronic infection phase. Transcriptome analyses of sorted KC and IMs using NanoString technology revealed two unique phenotypes with only minimal overlap. At the chronic viral infection phase, KC showed no increased transcription of activation markers Cd80 and Cd86, but an increased expression of genes related to antigen presentation, whereas monocytes were more activated and expressed higher levels of Tnf transcripts. Although both KCs and intrahepatic IM share the surface markers F4/80 and CD11b, their transcriptomes point towards distinctive roles during virus-induced chronic hepatitis.

Chronic hepatitis B: immune pathogenesis and emerging immunotherapeutics

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

The Effect of Chronic Hepatitis B Virus Infection on BDCA3+ Dendritic Cell Frequency and Function

Chronic hepatitis B virus (HBV) infection results from inadequate HBV-specific immunity. BDCA3⁺ dendritic cells (DCs) are professional antigen presenting cells considered to be important for antiviral responses because of specific characteristics, including high interferon-λ production. BDCA3⁺ DCs may thus also have a role in the immune response against HBV, and immunotherapeutic strategies aiming to activate DCs, including BDCA3⁺ DCs, in patient livers may represent an interesting treatment option for chronic HBV. However, neither the effect of chronic hepatitis B (CHB) infection on the frequency and function of BDCA3⁺ DCs in liver and blood, nor the effect of the viral surface protein (HBsAg) that is abundantly present in blood of infected individuals are known. Here, we provide an overview of BDCA3⁺ DC frequency and functional capacity in CHB patients. We find that intrahepatic BDCA3⁺ DC numbers are increased in CHB patients. BDCA3⁺ DCs from patient blood are not more mature at steady state, but display an impaired capacity to mature and to produce interferon-λ upon polyI:C stimulation. Furthermore, in vitro experiments exposing blood and intrahepatic BDCA3⁺ DCs to the viral envelope protein HBsAg demonstrate that HBsAg does not directly induce phenotypical maturation of BDCA3⁺ DCs, but may reduce IFN-λ production via an indirect unknown mechanism. These results suggest that BDCA3⁺ DCs are available in the blood and on site in HBV infected livers, but measures may need to be taken to revive their function for DC-targeted therapy.

Hepatitis B Virus Surface Antigen Activates Myeloid Dendritic Cells via a Soluble CD14-Dependent Mechanism

Hepatitis B virus (HBV) infection can cause chronic liver disease, which is associated with increased risk of liver cirrhosis, liver failure, and liver cancer. Clearance of HBV infection requires effective HBV-specific immunity; however, the immunological mechanisms that determine the development of effective HBV-specific immunity are poorly understood. Dendritic cells (DC) play a pivotal role in the regulation of antiviral immunity. Here, we investigated the interaction between HBV surface antigen (HBsAg), the main envelope glycoprotein of HBV, and BDCA1(+) myeloid dendritic cells (mDC). Exposure of peripheral blood-derived BDCA1(+) mDC to HBsAg resulted in strong DC maturation, cytokine production, and enhanced capacity to activate antigen-specific cytotoxic T cells (CTLs). By using neutralizing antibodies, crucial roles for CD14 and Toll-like receptor 4 (TLR4) in HBsAg-mediated BDCA1(+) mDC maturation were identified. Concordantly, HBsAg-mediated DC maturation required fetal calf serum (FCS) or human plasma, naturally containing soluble CD14 (sCD14). Intriguingly, HBsAg-induced DC maturation was significantly reduced in umbilical cord blood plasma, which contained less sCD14 than adult plasma, indicating that sCD14 is an important host factor for recognition of HBsAg by DC and subsequent DC activation. A direct interaction between sCD14 and HBsAg was demonstrated by using enzyme-linked immunosorbent assay (ELISA). Moreover, sCD14-HBsAg complexes were detected both in vitro and in sera of HBV-infected patients. The abundance of sCD14-HBsAg complexes varied between chronic HBV disease stages and correlated with activation of BDCA1(+) mDC in vivo We conclude that HBsAg activates BDCA1(+) DC via an sCD14-dependent mechanism. These findings provide important novel insights into the initiation of HBV-specific immunity and facilitate development of effective immunotherapeutic interventions for HBV.

IMPORTANCE

Hepatitis B virus (HBV) infection is a significant health problem, as it causes progressive liver injury and liver cancer in patients with chronic HBV infection, which affects approximately 250 million individuals worldwide. Some of the infected adults and the majority of neonates fail to mount an effective immune response and consequently develop chronic infection. The viral and host factors involved in the initiation of effective HBV-specific immune responses remain poorly understood. Here we identified CD14 and TLR4 as receptors for HBsAg, the main HBV envelope antigen. HBsAg induced strong maturation of dendritic cells (DC), which have a central role in regulation of virus-specific immunity. These results provide essential novel insights into the mechanisms underlying the initiation of HBV-specific immunity. Intriguingly, since neonates have naturally low sCD14, the finding that serum-derived sCD14 is a crucial host factor for recognition of HBsAg by DC may have implications for immunity of neonates to 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.

The Role of Immune Cells in Chronic HBV Infection

Hepatitis B virus (HBV) infection is a major cause of chronic liver diseases that may progress to liver cirrhosis and hepatocellular carcinoma. Host immune responses are important factors that determine whether HBV infection is cleared or persists. After infection, viral replication occurs inside hepatocytes, and the secretion of infectious virions can take place at high rates for decades. Consequently, HBV DNA and viral proteins, like HBV early antigen (HBeAg) and HBV surface antigen (HBsAg), can be easily detected in serum. Chronic infection with HBV is the result of an ineffective antiviral immune response towards the virus. In this review, we discuss the role of immune cells in chronic HBV infection.

Innate immune recognition of hepatitis B virus

Hepatitis B virus (HBV) is a hepatotropic DNA virus and its infection results in acute or chronic hepatitis. It is reported that the host innate immune system contributes to viral control and liver pathology, while whether and how HBV can trigger the components of innate immunity remains controversial. In recent years, the data accumulated from HBV-infected patients, cellular and animal models have challenged the concept of a stealth virus for HBV infection. This editorial focuses on the current findings about the innate immune recognition to HBV. Such evaluation could help us to understand HBV immunopathogenesis and develop novel immune therapeutic strategies to combat HBV infection.

miR-106a Is Downregulated in Peripheral Blood Mononuclear Cells of Chronic Hepatitis B and Associated with Enhanced Levels of Interleukin-8

Aims. This study aimed to investigate miR-106a expression in peripheral blood mononuclear cells (PBMCs) of chronic hepatitis B (CHB) patients and to analyze the function of miR-106a. Materials and Methods. miR-106a expression levels in PBMCs from 40 healthy controls and 56 CHB patients were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The luciferase activity assays were used to determine whether miR-106a binds to 3′UTR of IL-8. miR-106a mimics and inhibitors were transfected into healthy PBMCs. IL-8 mRNA and protein levels were detected and determined by qRT-PCR and ELISA, respectively. Results. The qRT-PCR results suggested that the PBMC miR-106a levels were decreased in CHB patients. IL-8 was augmented in CHB patients and was inversely correlated with miR-106a levels. The luciferase activity assays indicated that IL-8 is a target of miR-106a. Exogenous expression of miR-106a could significantly repress IL-8 expression at both mRNA and protein levels in PBMCs, whereas miR-106a inhibitor had the opposite effects. Conclusions. This study suggested that miR-106a is downregulated in PBMCs of CHB patients and that miR-106a may play an important role in CHB by targeting IL-8.

Hepatitis B virus large surface protein: function and fame

Chronic infection with hepatitis B virus (HBV) is the leading cause of liver cirrhosis and hepatocellular carcinoma worldwide. HBV life cycle begins with viral attachment to hepatocytes, mediated by the large HBV surface protein (LHBs). Identification of the sodium-taurocholate cotransporting polypeptide (NTCP) as a HBV receptor has revealed a suitable target for viral entry inhibition. Analysis of serum hepatitis B surface antigen (HBsAg) level is a non-invasive diagnostic parameter that improves HBV treatment opportunities. Furthermore, HBsAg plays an important role in manipulation of host immune response by HBV. However, observations in patients with chronic hepatitis B under conditions of immune suppression and in transgenic mouse models of HBV infection suggest, that in absence of adaptive immune responses cellular mechanisms induced by HBV may also lead to the development of liver diseases. Thus, the multifaceted pathological aspects of HBsAg predetermine the design of new therapeutical options modulating associated biological implications.

Significant roles of regulatory T cells and myeloid derived suppressor cells in hepatitis B virus persistent infection and hepatitis B virus-related HCCs

The adaptive immune system, including type1 helper T cells (Th1 cells), cytotoxic T lymphocytes (CTLs), and dendritic cells (DCs), plays an important role in the control of hepatitis B virus (HBV). On the other hand, regulatory T cells (Tregs) and myeloid derived suppressor cells (MDSCs) suppress the immune reaction in HBV and hepatocellular carcinoma (HCC). Excessive activation of immune suppressive cells could contribute to the persistent infection of HBV and the progression of HCC. The frequency and/or function of Tregs could affect the natural course in chronic hepatitis B patients and the treatment response. In addition to the suppressive function of MDSCs, MDSCs could affect the induction and function of Tregs. Therefore, we should understand in detail the mechanism by which Tregs and MDSCs are induced to control HBV persistent infection and HBV-related HCC. Immune suppressive cells, including Tregs and MDSCs, contribute to the difficulty in inducing an effective immune response for HBV persistent infection and HBV-related HCC. In this review, we focus on the Tregs and MDSCs that could be potential targets for immune therapy of chronic hepatitis B and HBV-related HCC.

Dissecting the dendritic cell controversy in chronic hepatitis B virus infection

Therapeutic vaccines to boost endogenous T-cell immunity rely on the stimulatory capacity of dendritic cells (DCs). The functionality of DCs in chronic hepatitis B virus (HBV) infection has been a long-standing debate. Therefore, we have attempted to summarize multiple studies investigating DC function in chronic HBV patients to determine whether common observations can be drawn. We found that the frequency and function of ex vivo-tested myeloid and plasmacytoid DCs were largely intact in patients with HBV infection and similar to those of healthy donor DCs. The main exception was reduced IFN-α production by plasmacytoid DC from chronic HBV patients. This reduced IFN-α production correlated with liver inflammation in multiple studies but not with viral load, suggesting that viral antigens have little effect on DC function. The majority of the confusion about DC function arises from studies reporting the reduced function of healthy donor DCs exposed to various sources of HBV in vitro. These direct effects of viral antigens are in contrast to data from HBV-infected patients. The variations in the assays used and areas that require further investigation are also covered.