Response to interferon-alpha treatment correlates with recovery of blood plasmacytoid dendritic cells in children with chronic hepatitis B

Interferon alpha treatment leads to a high rate of hepatitis B surface antigen seroconversion in Chinese children with chronic hepatitis B

Chronic hepatitis B virus (HBV) infection (CHB) in children remains a public health challenge despite significant success in programme is established to prevent mother-to-child transmission. In particular, CHB in Chinese children are mostly acquired through vertical transmission, which differs from the common infection route reported in other countries and regions. This situation has resulted in a high endemic prevalence of CHB in Chinese adults. Thus, successful treatment of children with CHB will prevent the development of advanced liver diseases in late adulthood. However, there is still no consensus on the clinical guideline to treat paediatric CHB. In this study, we evaluated the potential of interferon alpha (IFNa) treatment for Chinese children with CHB. A total of 41 patients with CHB aged 3-17 years were enrolled in this retrospective study: 21 patients were treated with pegylated (PEG)-IFNa and 20 patients without treatment served as the control group. The rates of HBV DNA suppression, hepatitis B e antigen (HBeAg) clearance and hepatitis B surface antigen (HBsAg) clearance were significantly higher in the PEG-IFNa treatment group than in the control group (P < 0.05 at 48 weeks). Unexpectedly, PEG-IFNa treatment achieved a high rate of HBsAb production, far exceeding the clinical outcome in documented PEG-IFNa-treated CHB adults. Further analysis revealed that younger children (3-6 years old) were more responsive to PEG-IFNa treatment with respect to achieving a protective level of HBsAb in a short treatment cycle than adolescents (10-17 years old). Overall, these results indicate that the immune system of children might have a preserved PEG-IFNa-mediated mechanism to completely control HBV, which can help to design new strategies to treat CHB patients.

Frequencies of dendritic cells and Toll-like receptor 3 in neonates born to HBsAg-positive mothers with different HBV serological profiles

To investigate the frequencies of dendritic cells (DCs) and Toll-like receptor 3 (TLR3) in neonates of HBsAg-positive mothers with different HBV serological profiles, we conducted a study in Taiyuan, China. The study included 144 HBsAg-positive mothers and their neonates. The frequencies of DCs and TLR3 were determined using four-colour flow-cytometric analysis. DC and TLR3 frequencies were not related to HBV intrauterine transmission, maternal HBeAg positivity, maternal HBV DNA positivity and HBeAg/HBV DNA double-positivity. The plasmacytoid dendritic cell (pDC) frequencies in neonates whose maternal HBV DNA was >5 × 107 copies/ml decreased significantly compared to that in neonates whose maternal HBV DNA was ⩽5 × 107 copies/ml (Z = - 2·170, P = 0·03) or whose maternal HBV DNA was negative (Z = - 1·981 P = 0·048). This study suggests that neonatal pDC frequencies decrease when maternal HBV DNA loads are >5 × 107 copies/ml.

Plasmacytoid dendritic cells induce efficient stimulation of antiviral immunity in the context of chronic hepatitis B virus infection

The immune control of hepatitis B virus (HBV) infection is essential for viral clearance. Therefore, restoring functional anti-HBV immunity is a promising immunotherapeutic approach to treatment of chronic infection. Plasmacytoid dendritic cells (pDCs) play a crucial role in triggering antiviral immunity through their ability to capture and process viral antigens and subsequently induce adaptive immune responses. We investigated the potential of pDCs to trigger antiviral cellular immunity against HBV. We used a human leukocyte antigen A (HLA-A)*0201(+) pDC line loaded with HLA-A*0201-restricted peptides derived from hepatitis B core/hepatitis B surface (HBc/HBs) antigens to amplify specific CD8 T cells ex vivo from chronic HBV patients and established a Hepato-HuPBL mouse model to address the therapeutic potential of the strategy in vivo. Stimulation of PBMCs or liver-infiltrating lymphocytes from HLA-A*0201(+) chronic HBV patients by HBc peptide-loaded pDCs elicited up to 23.1% and 76.1% HBV-specific CD8 T cells in 45.8% of cases. The specific T cells from the "responder" group secreted interferon-γ, expressed CD107 upon restimulation, and efficiently lysed HBV antigen-expressing hepatocytes. Circulating hepatitis B e antigen (HBeAg) was found to distinguish the group of patients not responding to the pDC stimulation. The therapeutic efficacy of the pDC vaccine was evaluated in immunodeficient NOD-SCID β(2) m(-/-) mice reconstituted with HBV patients' PBMCs and xenotransplanted with human HBV-transfected hepatocytes. Vaccination of Hepato-HuPBL mice with the HBc/HBs peptide-loaded pDCs elicited HBV-specific T cells able to specifically lyse the transfected hepatocytes and reduce the systemic viral load.

CONCLUSION

pDCs loaded with HBV-derived peptides can elicit functional virus-specific T cells. HBeAg appears to be critical in determining the outcome of immunotherapies in chronic HBV patients. A pDC-based immunotherapeutic approach could be of interest in attempts to restore functional antiviral immunity, which is critical for the control of the virus in chronic HBV patients.

Immunopathogenesis and prognostic immune markers of chronic hepatitis B virus infection

Host immune responses induced by hepatitis B virus (HBV) infection not only substantially drive disease progression, but also significantly influence efficacy of antiviral treatments in HBV-infected individuals. Therefore, it is important to fully understand the course of immune pathogenesis and to find efficient immunological markers that can predict the disease progression of chronic HBV infection. This review introduces the current progress in clinical immunology and analyzes the mechanisms of antiviral effects and liver injury, which are induced by both innate and adaptive immune responses. The recently identified immunological markers indicated to be closely correlated with disease progression and antiviral efficacy during HBV infection are also summarized. Careful monitoring of these immune markers may help physicians to make decisions on when to begin or withdraw antiviral drugs, or to formulate the prognosis of acute-on-chronic liver failure (ACLF) patients in the clinic. Finally, this review highlights some novel therapeutic strategies to modulate host immunity that have been proposed to sustain antiviral control of chronic HBV infection, as well as the challenges that we are presently facing in the field.

Improved survival ratios correlate with myeloid dendritic cell restoration in acute-on-chronic liver failure patients receiving methylprednisolone therapy

Acute-on-chronic liver failure (ACLF) is a severe life-threatening complication. Liver transplantation is the only available therapeutic option; however, several limitations have restricted its use in patients. The use of corticosteroids as an optional therapy for ACLF has received a great deal of interest. The rationale behind its use is the possible role of the immune system in initiating and perpetuating hepatic damage. In order to assess the relationship between myeloid dendritic cells (mDCs) and the efficacy of methylprednisolone (MP) treatment for hepatitis B virus (HBV)-associated ACLF patients, we recruited 30 HBV-associated ACLF patients who had received MP treatment at 10-day intervals; 26 patients received conservative medical (CM) management as a control. The functionality of DC subsets was lower in these ACLF patients compared with healthy subjects. In addition, compared with survivors, dead/transplanted patients had lower functional mDC in both groups. Furthermore, a decreased numbers of mDC at baseline was associated with high mortality of ACLF patients. Importantly, MP treatment resulted in a significant decrease in 28-day mortality, and all MP patients exhibited an initial rapid decrease in circulating mDC numbers within 10 days of MP treatment. Subsequently, MP survivors displayed a continuous increase in mDC numbers accompanied by a decrease in total bilirubin levels by more than 30%. However, MP dead/transplanted patients lacked these sequential responses compared with survivors. This evidence suggests strongly that the higher mDC numbers at baseline and the recovery of mDC number at the end of treatment may represent a prognostic marker for favorable response to corticosteroid treatment in ACLF patients.

The tug-of-war between dendritic cells and human chronic viruses

The human immune system is under constant challenge from many viruses, some of which the body is successfully able to clear. Other viruses have evolved to escape the host immune responses and thus persist, leading to the development of chronic diseases. Dendritic cells are professional antigen-presenting cells that play a major role in both innate and adaptive immunity against different pathogens. This review focuses on the interaction of different chronic viruses with dendritic cells and the viruses' ability to exploit this critical cell type to their advantage so as to establish persistence within the host.

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.

Dendritic cells in uninfected infants born to hepatitis B virus-positive mothers

Plasmacytoid dendritic cells (pDCs) play a central role in antiviral immunity, detecting viruses via Toll-like receptors (TLR) and producing in response vast amounts of type I interferons (IFNs). Hepatitis B virus (HBV) causes chronic infection after vertical transmission. This study investigated whether an HBV-infected maternal environment might influence DC numbers and pDC function in uninfected infants. Blood was collected from inactive HBsAg carrier and control mothers and their infants at birth and 1 and 6 months of age. HBV DNA was measured in maternal and neonatal perinatal sera using real-time PCR. The circulating frequencies of myeloid DCs (mDCs) and pDCs were determined in the babies by flow cytometry. Peripheral blood mononuclear cells (PBMCs) and cord blood pDCs were stimulated with resiquimod, and alpha interferon (IFN-alpha) production and the pDC phenotype were assessed. The effect of the common-cold virus, rhinovirus (RV), on resiquimod stimulation was also determined. HBV DNA was detected in 62.3% of the mothers and 41% of their infants. DC numbers and pDC functions were similar between subjects and controls and were not correlated with maternal or neonatal viremia. RV infection did not induce pDC maturation until the age of 6 months, and it reduced TLR7-dependent resiquimod-induced IFN-alpha production similarly in both groups. Although the DC system is immature at birth, DCs of uninfected neonates of HBV-positive mothers are competent to initiate and maintain T-cell responses. RV is a weak inducer of IFN-alpha production until the age of 6 months and inhibits IFN-alpha responses triggered by the TLR7 pathway.

Plasmacytoid dendritic cells in antiviral immunity and autoimmunity

Plasmacytoid dendritic cells (pDCs) represent a unique and crucial immune cell population capable of producing large amounts of type I interferons (IFNs) in response to viral infection. The function of pDCs as the professional type I IFN-producing cells is linked to their selective expression of Toll-like receptor 7 (TLR7) and TLR9, which sense viral nucleic acids within the endosomal compartments. Type I IFNs produced by pDCs not only directly inhibit viral replication but also play an essential role in linking the innate and adaptive immune system. The aberrant activation of pDCs by self nucleic acids through TLR signaling and the ongoing production of type I IFNs do occur in some autoimmune diseases. Therefore, pDC may serve as an attractive target for therapeutic manipulations of the immune system to treat viral infectious diseases and autoimmune diseases.

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

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

Advance in molecular mechanism of interferon to treat chronic hepatitis B

The antiviral efficacy of interferon-α (IFN-α) therapy for chronic hepatitis B (CHB) is not only related to DNA load and genetype of HBV before treatment, gene mutation of HBV and polymorphism of type II HLA in the host, but also depends on the immunity of CHB patients. Researchers pay more and more attention to the mutant strain of virus and phenotypes of genes. However, the mechanism of interferon to resist HBV and the escape mechanism of HBV against the IFN therapy have not been clarified yet. This paper reviews the mechanism of IFN therapy and the influencing factors at molecular and genetic levels.

Viral suppression correlates with dendritic cell restoration in chronic hepatitis B patients with autologous cytokine-induced killer cell transfusion

BACKGROUND

Myeloid and plasmacytoid dendritic cells (mDCs, pDCs) are functionally impaired in patients with chronic hepatitis B (CHB). Adoptive immunotherapy can suppress hepatitis B virus (HBV) replication in CHB patients, but whether it can restore the functionality of mDCs and pDCs remains unknown.

METHODS

Autologous cytokine-induced killer (CIK) cells obtained from 14 CHB patients were transfused back to patients, case by case, to observe the effect of CIK-cell treatment on the frequency and functionality of mDCs and pDCs in CHB patients during a 24-week follow-up investigation.

RESULTS

Seven virological responders exhibited a sustained decrease in HBV load after CIK-cell transfusion; another seven non-virological responders showed only sustained high levels of HBV load during the 24-week period following CIK-cell transfusion. The rate of hepatitis B e antigen loss or seroconversion was also higher in virological responders than in non-virological responders. Importantly, we found that the frequency and cytokine-producing capacity of mDCs and pDCs increased significantly in virological responders, but not in non-virological responders. In addition, these patients exhibited a close correlation between restoration DC subsets and a decrease in HBV DNA load, rather than a change in the alanine aminotransferase level.

CONCLUSION

Cytokine-induced killer-cell treatment reduced HBV DNA load in some CHB patients; the efficiency at least partially correlates with the restoration of frequency and functionality of mDCs and pDCs.

Severe dendritic cell perturbation is actively involved in the pathogenesis of acute-on-chronic hepatitis B liver failure

BACKGROUND/AIMS

Functionally impaired dendritic cells (DCs) play important roles in suppressing host immune responses and facilitating viral persistence in chronic hepatitis B virus (HBV) infection. However, little is known regarding the status of intrahepatic DCs in HBV infection.

METHODS

Based on availability, 11 recipient liver samples were obtained from acute-on-chronic hepatitis B liver failure (ACHBLF) patients who had undergone liver transplantation. The frequencies, phenotypes, and functions of intrahepatic DC subsets were analyzed.

RESULTS

Both plasmacytoid dendritic cells (pDCs) and myeloid dendritic cells (mDCs) extensively infiltrated the liver of the ACHBLF patients and expressed mature phenotypes therein. In particular, activated hepatic pDCs produced interferon (IFN)-alpha, which subsequently induced interleukin (IL)-12 and IL-10 production via toll-like receptor-9 ligation in liver-infiltrating lymphocytes cultured in vitro. However, blockade of IFN-alpha production significantly reduced the cytokine production of the LILs. Further, a significantly low frequency of peripheral pDCs and highly reduced IFN-alpha production were observed in a large cohort of the ACHBLF patients, particularly in the non-survivors. Moreover, a persistently upregulated expression of hepatic IFN-alpha-associated genes was observed in the ACHBLF patients during disease progression.

CONCLUSIONS

Activated pDCs accumulated in large numbers in the liver of the ACHBLF patients and regulated local immune responses in chronic HBV infection.