Mechanism of action of vaccine therapy in murine hepatitis B virus carriers: vaccine-induced activation of antigen presenting dendritic cells

Cellular and Molecular Mechanisms of Pathogenic and Protective Immune Responses to SARS-CoV-2 and Implications of COVID-19 Vaccines

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has devastated the world with coronavirus disease 2019 (COVID-19), which has imparted a toll of at least 631 million reported cases with 6.57 million reported deaths. In order to handle this pandemic, vaccines against SARS-CoV-2 have been developed and billions of doses of various vaccines have been administered. In the meantime, several antiviral drugs and other treatment modalities have been developed to treat COVID-19 patients. At the end of the day, it seems that anti-SARS-CoV-2 vaccines and newly developed antiviral drugs may be improved based on various new developments. COVID-19 represents a virus-induced, immune-mediated pathological process. The severity of the disease is related to the nature and properties of the host immune responses. In addition, host immunity plays a dominant role in regulating the extent of COVID-19. The present reality regarding the role of anti-SARS-CoV-2 vaccines, persistence of SARS-CoV-2 infection even three years after the initiation of the pandemic, and divergent faces of COVID-19 have initiated several queries among huge populations, policy makers, general physicians, and scientific communities. The present review aims to provide some information regarding the molecular and cellular mechanisms underlying SARS-CoV-2 infection.

Exploring evidence-based innovative therapy for the treatment of chronic HBV infection: experimental and clinical

With the advent of various vaccines and antimicrobial agents during the 20th century, the control and containment of infectious diseases appeared to be a matter of time. However, studies unveiled the diverse natures of microbes, their lifestyle, and pathogenetic potentials. Since the ground-breaking discovery of the hepatitis B virus (HBV) by Baruch Blumberg and the subsequent development of a vaccine in the early 1980s, the main task of the scientific community has been to develop a proper management strategy for HBV-induced chronic liver diseases. In the early 1980’s, standard interferon (IFN) induced a reduction of HBV DNA levels, followed by the normalization of serum transaminases (alanine aminotransferase, ALT), in some chronic hepatitis B (CHB) patients. However, in the course of time, the limitations of standard IFN became evident, and the search for an alternative began. In the late 1980’s, nucleoside analogs entered the arena of CHB treatment as oral drugs with potent antiviral capacities. At the beginning of the 21st century, insights were developed into the scope and limitations of standard IFN, pegylated-IFN as well as nucleoside analogs for treating CHB. Considering the non-cytopathic nature of the HBV, the presence of covalently closed circular DNA (cccDNA) in the nucleus of the infected hepatocytes and HBV-induced immune-mediated liver damages, a new field of CHB management was initiated by modulating the hosts’ immune system through immune therapy. This review will discuss the nature and design of innovative immune therapy for CHB.

Recombinant HBV vaccine enhances the rate of sustained virological response when early initiated after anti-HCV combination therapy

The overall SVR rate for chronic hepatitis C genotype 4 using the Standard of care is 54.3%. HBV infection can be prevented by the administration of effective and safe vaccine. Evaluation of the vaccination-induced anti-HBs response rates in a cohort of HCV Egyptian patients after being exposed to antiviral combination therapy and the magnitude of its effect on the rate of SVR through its putative role in induction of crossed immunity. (A) 500 HCV patients who had completed the course of antiviral therapy and achieved ETR were retrospectively analyzed and received 20 μg of recombinant DNA vaccine for hepatitis B at time intervals (0, 1, and 4 months). The first dose of the vaccine was initiated one month post treatment. (B) Laboratory analysis: Included routine preliminary investigations to anti viral therapy and specific investigations as determination of anti-HBs antibodies 2 months following the third dose of vaccine. 433 patients showed protective response (86.6%), 67 patients were non-responders (13.4%) (P = 0.003). Adding HBV vaccine 1 month post-treatment increased SVR (400 patients, 80%) (χ(2)  = 40.3, P = 0.000). Diabetes affect response to HBV vaccine (P = 0.0001). Adding HBV vaccine to the post treatment care of patients with HCV after termination of antiviral therapy gain two benefits; protection from HBV and significant increase in rates of SVR.

Hepatitis B virus infection: An insight into infection outcomes and recent treatment options

Hepatitis B virus (HBV) currently infects an estimated population of 2 billion individuals in the world, including 400 million people with chronic HBV infection. HBV virology, replication and the host's immune response to HBV infection contribute to different infection outcomes. Acute hepatitis HBV infection is self-limiting but it leaves a residual infection that can become active in an individual during immunosuppression. In chronic HBV infection, the virus persistently replicates in hepatocytes leading to immune mediated hepatocellular damage. Despite the inability to remove the virus in more than 70 % of patients, current treatments for chronic HBV infection, interferon alpha and antiviral nucleotide/nucleoside analogues, aim to reduce viral replication to prevent or at least delay the progression to cirrhosis and hepatocellular carcinoma. In both self resolved acute and persistent HBV infection, the long term existence of chromatinised covalently closed circular DNA (cccDNA) in the nuclei of infected hepatocytes cannot be targeted by current treatments to eliminate these templates to eradicate the viral persistence. Identifying the mechanisms involve in the removal of infected hepatocytes will be useful as treatment options. In this context, DNA based novel therapeutic and immunization strategies might help to remove stable cccDNA and thus viral persistence.

IgE anti Hepatitis B virus surface antigen antibodies detected in serum from inner city asthmatic and non asthmatic children

Viral Hepatitis type B (HBV) is a public health concern, but has not been linked to asthma. Immunoglobulin (Ig) G is involved in HBV immune responses; less is known about IgE antibodies (Abs) against HBV in asthma. Given the importance of HBV, we sought to determine whether HBV vaccine contributes to asthma in children, by stimulating specific IgE production. Total IgE, IgE- or IgG-anti-HBVs Abs were studied in vaccinated pediatric asthmatics and non asthmatics. We found: (1) total IgE was higher in asthmatics; (2) total IgE did not correlate with IgE anti-HBVs; (3) IgE anti-HBVs did correlate with IgG-anti-HBVs in all subjects; (4)IgE- and IgG-HBVs Abs were similar in both groups; (5) IgE- or IgG anti-HBVs Abs did not correlate with age. Our findings indicate that HBV vaccination induces IgE responses in asthmatics and non asthmatics.

HBsAg, HBcAg, and combined HBsAg/HBcAg-based therapeutic vaccines in treating chronic hepatitis B virus infection

BACKGROUND

As the host immunity is diminished in patients with chronic hepatitis B (CHB), different approaches have been used to up-regulate their immune responses to produce therapeutic effects. But, cytokines, growth factors and polyclonal immune modulators could not exhibit sufficient therapeutic effects in these patients. Immune therapy with HBV-related antigens (vaccine therapy) has been used in CHB patients. But there is a paucity of information about the design of HBV antigen-based immune therapy in these patients.

DATA SOURCE

Preclinical and clinical studies on immune therapy with HBsAg-based vaccine, HBcAg and combination of HBsAg/HBcAg-based vaccines have been discussed.

RESULTS

HBsAg-based prophylactic vaccine was used as an immune therapeutic agent in CHB patients; however, monotherapy with HBsAg-based immune therapy could not lead to sustained control of HBV replication and/or liver damages. HBsAg-based vaccine was used as a combination therapy with cytokines, growth factors, and antiviral drugs. HBsAg-based vaccine was also used for cell-based therapy. However, satisfactory therapeutic effects of HBsAg-based vaccine could not be documented in CHB patients. In the mean time, evidences have supported that HBcAg-specific immunity is endowed with antiviral and liver protecting capacities in CHB patients. Recent data concentrate on the clinical use of combined HBsAg- and HBcAg-based vaccines in CHB patients.

CONCLUSION

Antigen-based immune therapy with HBV-related antigens may be an alternative method for the treatment of CHB patients but proper designs of antigens, types of adjuvants, dose of vaccinations, and routes of administration need further analyses for the development of an effective regimen of immune therapy against HBV.

Non-antigen-specific and antigen-specific immune therapies for chronic hepatitis B: evidences from laboratory benches and patient's bedsides

INTRODUCTION

Due to unsatisfactory therapeutic efficacy and considerable side effects of antiviral drugs in patients with chronic hepatitis B (CHB), immunotherapy has emerged as an alternative approach. CHB immunotherapy may be categorized into two main types: i) non-antigen-specific immune therapy and ii) hepatitis B virus (HBV) antigen-specific immune therapy. Although different immune modulators have been used in CHB patients for the last two to three decades, the nature and design of ongoing regimens of immunotherapeutic approaches need considerable modifications.

AREAS COVERED

In this review, the authors have outlined the relevant immunotherapies for CHB patients that have been used for the last two to three decades. The mechanisms underlying the limited therapeutic efficacy of available therapeutic agents for CHB patients have been discussed to aid in the development of an effective therapeutic approach for these patients.

EXPERT OPINION

Circumstantial evidence indicates that a better regimen of immunotherapy may be developed using different HBV-related antigens or combinations of two or more HBV-related antigens, or combinations of HBV-related antigens and antiviral drugs. However, the capacity of 'inducible immunity' by immune modulators to cure or block progression of liver diseases in CHB patients needs to be addressed.

Hepatitis B virus surface antigen can activate dendritic cells and modulate T helper type immune response

Hepatitis B virus surface antigen (HBsAg) is a major antigen of hepatitis B virus (HBV). Dendritic cells (DC) of HBV carriers have been reported to exhibit functional impairment. In this study, the role of HBsAg on mice bone marrow-derived dendritic cells and immune responses in vivo was studied. The immune modulatory function of HBsAg was explored by using mice bone marrow-derived dendritic cells in vitro and also by examining an ovalbumin (OVA) specific immune response in vivo. Treatment of dendritic cells with HBsAg resulted in enhanced cell surface expression of cluster of differentiation (CD) 80, CD83, CD86, and major histocompatibility complex (MHC) class II, and enhanced production of interleukin (IL)-12 p40 and IL-12 p70. Treatment of dendritic cells with HBsAg resulted in decreased T cell secretion of IL-5 by OVA stimulation. In addition, the results showed stronger OVA-specific immunoglobulin (Ig) M and weaker IgG responses in mice sera when they had been immunized with OVA and co-injected with HBsAg. It was also found that the mice exhibited significant enhancement of anti-OVA IgG2a antibody (Ab), as well as marked inhibition of IgG1 Ab production. In cellular immune responses, IL-5 production was significantly decreased and interferon (IFN)-γ increased in the group co-injected with HBsAg. On the other hand, the induction of lymphoproliferative response to OVA stimulation in spleen cells was decreased in the HBsAg co-injected group. These results demonstrate that HBsAg can affect the differentiation of T helper (Th) cells, which might provide a strategy for improving its prophylactic and therapeutic efficacy.

Immune modulator and antiviral potential of dendritic cells pulsed with both hepatitis B surface antigen and core antigen for treating chronic HBV infection

BACKGROUND

Commercially available prophylactic vaccines containing hepatitis B surface antigen (HBsAg), which are used to prevent HBV infections, are not as effective as a therapeutic immune modulator for treating patients with chronic hepatitis B (CHB). In this study, the immunogenicity of dendritic cells (DC) loaded with both HBsAg and hepatitis B core antigen (HBcAg) was tested in HBV transgenic mice (TM; 1.2HB-BS10) in vivo and in patients with CHB in vitro.

METHODS

Spleen DC from HBV TM were cultured with a vaccine containing both HBsAg and HBcAg to produce HBsAg/HBcAg-pulsed DC. HBV TM were immunized twice at an interval of 4 weeks with HBsAg/HBcAg-pulsed DC and other immune modulators. Antibody titres to HBsAg (anti-HBs) were measured in sera. Antigen-specific T-cells and cytotoxic T-lymphocytes (CTLs) in the spleen and liver were detected by lymphoproliferative and ELISPOT assays, respectively. HBsAg/HBcAg-pulsed human blood DC were cultured with autologous T-cells from CHB patients to assess their antigen-specific immune modulatory capacities.

RESULTS

Significantly higher levels of anti-HBs, HBsAg-specific and HBcAg-specific T-cells and CTLs were detected in the spleen and liver of HBV TM immunized with HBsAg/HBcAg-pulsed DC compared with those immunized with other vaccine formulations (P<0.05). HBsAg/HBcAg-pulsed human blood DC also induced HBsAg- and HBcAg-specific proliferation of autologous T-cells from CHB patients.

CONCLUSIONS

The immune modulatory capacities of HBsAg/HBcAg-pulsed DC in HBV TM in vivo, and in patients with CHB in vitro, inspire optimism about a clinical trial with this cell-based vaccine in patients with CHB.

Impaired dendritic cell functions disrupt antigen-specific adaptive immune responses in mice with nonalcoholic fatty liver disease

BACKGROUND/AIMS

The magnitude of antigen-specific immunity was assessed in a murine model of nonalcoholic fatty liver diseases (NAFLD). Because antigen-specific immunity was diminished in NAFLD mice, the underlying mechanisms were evaluated through analysis of the functions of antigen-presenting dendritic cells (DC) and other immunocytes.

METHODS

For 12 weeks, NAFLD mice received a high-fat (60%) and high-calorie (520 kcal/100 g) diet. C57BL/6 mice (controls) received a standard diet. NAFLD mice and control mice were immunized with hepatitis B vaccine containing hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg). Antibody to HBsAg (anti-HBs), HBsAg and HBcAg-specific cellular immune response and functions of whole spleen cells, T lymphocytes, B lymphocytes and spleen DCs of NAFLD and control mice were assessed in vitro.

RESULTS

Levels of anti-HBs and the magnitude of proliferation of HBsAg and HBcAg-specific lymphocytes were significantly lower in NAFLD mice than control mice (P < 0.05). The spleen cells of NAFLD mice produced significantly higher levels of inflammatory cytokines (P < 0.05) and exhibited significantly increased T cell proliferation compared with control mice (P < 0.05). However, the antigen processing and presenting capacities of spleen DCs were significantly decreased in NAFLD mice compared with control mice (P < 0.05). Palmitic acid, a saturated fatty acid, caused diminished antigen processing and presenting capacity of both murine and human DCs.

CONCLUSIONS

Nonalcoholic fatty liver disease mice exhibit decreased magnitudes of antigen-specific humoral and cellular immune responses. This effect is mainly, if not solely, due to impaired antigen processing and presentation capacities of DC.

Randomized controlled study investigating viral suppression and serological response following pre-S1/pre-S2/S vaccine therapy combined with lamivudine treatment in HBeAg-positive patients with chronic hepatitis B

The aim of the current study was to evaluate viral suppression following combined treatment with an S/pre-S1/pre-S2 vaccine and lamivudine in patients with chronic hepatitis B. We established a randomized, controlled clinical trial to compare the responses of three different treatment groups: those receiving vaccine monotherapy, lamivudine monotherapy, or combination treatment. Viral response was evaluated via hepatitis B virus (HBV) DNA suppression using different levels of classification. Seroconversion was evaluated via HBeAg loss, HBeAg seroconversion, HBsAg loss, and anti-HBs response. We found that the group receiving combination treatment demonstrated a significant increase in viral suppression over that for the lamivudine or vaccine monotherapy group, although the HBeAg seroconversion rate was not different. This enhanced suppression effect in the combination group was reversed after the discontinuation of vaccine treatment, suggesting that booster doses are required for a sustained viral response. Anti-HBs was detected in 55/120 vaccine recipients, but only 3 patients demonstrated HBsAg loss, indicating that the vaccine-induced anti-HBs was unable to completely neutralize HBsAg in the serum. At the study end point, anti-HBs responders showed significantly higher HBeAg seroconversion rates, greater suppression of HBV DNA levels, and a lower median reduction in HBV DNA levels than those of anti-HBs nonresponders. Our results suggest that combined treatment with the vaccine and lamivudine was significantly more effective than lamivudine monotherapy in the short term and was especially successful in producing viral suppression and an enhanced anti-HBs antibody response.

Impaired dendritic cell functions because of depletion of natural killer cells disrupt antigen-specific immune responses in mice: restoration of adaptive immunity in natural killer-depleted mice by antigen-pulsed dendritic cell

The primary aim of this study was to evaluate the role of natural killer (NK) cells on antigen-specific adaptive immune responses. After analysing the mechanism of impaired adaptive immune responses of NK-depleted mice, an immune interventional approach was developed to restore adaptive immunity in NK-depleted mice. NK cells were depleted from mice by administration of anti-asialo GM1 antibody (100 mul/mouse), twice, at an interval of 48 h. Hepatitis B surface antigen (HBsAg) was administered intraperitoneally to normal C57BL/6 mice (control mice) and NK-depleted mice. The levels of antibody to HBsAg (anti-HBs) in the sera and HBsAg-specific lymphocytes in the spleen were assessed. The functions of T lymphocytes, B lymphocytes and dendritic cells (DCs) were evaluated in vitro. HBsAg-pulsed DCs were prepared by culturing spleen DCs with HBsAg for 48 h and administered once to NK-depleted mice. The levels of anti-HBs in the sera and HBsAg-specific lymphocytes were significantly lower in NK-depleted mice compared with control mice (P < 0.05). The functions of T and B lymphocytes were similar between control mice and NK-depleted mice. However, the functions of spleen DC and liver DC were significantly lower in NK-depleted mice compared with control mice (P < 0.05). Administration of HBsAg-pulsed DCs, but not HBsAg, induced HBsAg-specific humoral and cellular immune responses in NK-depleted mice. Our study suggests that cross-talk between NK cells and DCs regulates the magnitude of adaptive immunity. In addition, antigen-pulsed immunogenic DCs represent potent immune modulator even if subjects with diminished innate immunity.

Engineering immune therapy against hepatitis B virus

Approximately 350-400 million people worldwide are chronically infected with the hepatitis B virus (HBV). These individuals harbor the virus for their whole life and they transmit the virus to uninfected individuals. In addition, considerable numbers of chronic HBV carriers develop progressive liver diseases like chronic hepatitis B, liver cirrhosis and hepatocellular carcinoma. At present, antiviral agents like type-1 interferons, lamivudine, adefovir and entacavir are used to treat a selected population of chronic HBV carriers. These antiviral treatments are not satisfactory in that they are unable to eradicate HBV, only partially efficient in less than 30% subjects, expensive, can have debilitating side-effects and require constant monitoring. In addition, once treatment is stopped, the virus and clinical conditions return in many patients. Recent advancements in cellular and molecular biology indicate that the host's immune responses to HBV play cardinal roles during acquisition, pathogenesis, progression, and complications of chronic HBV infection. Immune responses are also important in the context of antiviraltherapy and clinical recovery. This explains why the efficacy of antiviral drugs is limited even in some selected patients with chronic HBV infection. Various published work now state that HBV-specific immunity may be beneficial for patients with chronic HBV infection and non-HBV-specific immunity may be related to flare up of liver diseases. Accordingly, a new few field of immunological research and clinical application of prophylactic vaccines (vaccine therapy) has been started in chronic HBV carriers. Vaccine therapy has inspired optimism as a new therapeutic approach, but it is unlikely that the present regimen of vaccine therapy will stand the test of time. Based on present understandings about vaccine/host interactions, we provide herein an outline for engineering more potent regimen of HBV-specific immune therapy against HBV.

Use of hepatitis B vaccine for the treatment of chronic hepatitis B

Current therapeutic approaches to control chronic hepatitis B (CH-B), such as administrations of interferon or nucleoside analogs, are still unsatisfactory. Vaccination with conventional hepatitis B (HB) vaccine is another therapeutic approach with lower cost and potentially long-lasting beneficial effect. However, a response rate to vaccination therapy is not necessarily high. Therefore, combination therapy of interferon, nucleoside analogs and vaccination, would be the promising therapeutic approach that improves therapeutic effect and solves the problems of individual therapies. Herein, we report the results of the clinical trial, the combination therapy of lamivudine (LAM) and HB vaccine in patientswith B-CH as one of the candidates for the combination therapies. The results indicate that the combination therapy of LAM and HB vaccine was more effective in regulating viral replication than the LAM monotherapy was. In addition, no adverse effect was observed in the patients given HB vaccine. This novel therapy should be further examined for the improvement of its efficacy and achievement of continuous suppression of HB virus replication.

Combination therapy with lamivudine and HB vaccine on chronic hepatitis B

BACKGROUND AND AIM

Lamivudine (LAM) has problems of breakthrough hepatitis (BTH) and post-treatment relapse despite its significant effect for suppressing hepatitis B virus (HBV) replication. In order to find solutions for the problems, the efficacy of combination therapy of LAM plus hepatitis B (HB) vaccine in patients with chronic HBV infection was assessed.

PATIENTS AND METHODS

Fifty-three patients with chronic hepatitis B, 33 hepatitis B e-antigen positive (HBeAg+), and 20 HBeAg negative (HBeAg-) patients, were enrolled in the study, and randomized to receive either LAM monotherapy or combination therapy of LAM and HB vaccine. In the combination therapy group, 100 mg/day of LAM was administered as a baseline therapy, and 10 mug of HB vaccine was injected subcutaneously every month starting at 2 months after LAM administration, six times in total.

RESULTS

HBeAg negative patients responded well to LAM therapy, and there were no significant differences in short-term effects between the two therapy groups. With regard to the ratio of developing BTH, there was no difference betweenthe two groups. In HBeAg+ patients, HBV replication was suppressed more efficiently in the combination therapy group than in the monotherapy group. The ratio of developing BTH was significantly lower in the combination therapy group than in the monotherapy group. Regardless of HBeAg serologic status or therapy protocols, post-treatment relapse was seen in most patients when the administrations of LAM were discontinued. No adverse effect with the use of HB vaccine was observed in all the patients treated with the combination therapy.

CONCLUSION

Combination therapy of LAM and HB vaccine is a safe and effective way to control HBV replication and prevent the development of BTH especially in patients with high viral load. However, further study is required in order to achieve the continuous suppression of HBV replication even after cessation of LAM.

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.

Impaired dendritic cell function resulting from chronic undernutrition disrupts the antigen-specific immune response in mice

We examined whether antigen-specific immune responses are lower in mice with protein energy malnutrition (PEM mice) compared with nourished (control) mice. The mechanisms underlying reduced antigen-specific immune responses of PEM mice were evaluated through analysis of the functional capacities of antigen-presenting dendritic cells (DC). PEM mice were produced by subjecting male C57BL/6 mice for 52 wk to a daily food intake equivalent to 70% of the mean amount consumed by the control mice that consumed food ad libitum. PEM mice and control mice were immunized with hepatitis B vaccine containing hepatitis B surface antigen (HBsAg) at 52 wk and humoral and cellular immune responses to HBsAg were evaluated at 58 wk. Lymphoproliferative assays were performed to assess the functional capacities of lymphocytes and DC. After 52 wk of food restriction, PEM mice had a 49% lower body weight than controls, almost no subcutaneous fat, severe muscle wasting, and atrophied spleen. All control mice developed antibodies to HBsAg (anti-HBs) in the sera and HBsAg-specific lymphocytes in the spleen as a result of immunization with the hepatitis B vaccine. PEM mice, however, were almost unresponsive to immunization with the hepatitis B vaccine. In PEM mice, the numbers of spleen DC, the T lymphocyte stimulatory capacities of DC, and their production of IL-12p70 and IFN-gamma was less than those of control mice (P < 0.05). We suggest that chronic undernutrition disrupts antigen-specific immune responses and that this disruption can be attributed at least in part to reduced frequencies and impaired functions of DC.

Immune therapy including dendritic cell based therapy in chronic hepatitis B virus infection

Hepatitis B virus (HBV) infection is a global public health problem. Of the approximately 2 billion people who have been infected worldwide, more than 400 million are chronic carriers of HBV. Considerable numbers of chronic HBV carriers suffer from progressive liver diseases. In addition, all HBV carriers are permanent source of this virus. There is no curative therapy for chronic HBV carriers. Antiviral drugs are recommended for about 10% patients, however, these drugs are costly, have limited efficacy, and possess considerable side effects.

Recent studies have shown that immune responses of the host to the HBV are critically involved at every stage of chronic HBV infection: (1) These influence acquisition of chronic HBV carrier state, (2) They are important in the context of liver damages, (3) Recovery from chronic HBV-related liver diseases is dependent on nature and extent of HBV-specific immune responses. However, induction of adequate levels of HBV-specific immune responses in chronic HBV carriers is difficult. During the last one decade, hepatitis B vaccine has been administered to chronic HBV carriers as a therapeutic approach (vaccine therapy). The present regimen of vaccine therapy is safe and cheap, but not so effective. A dendritic cell-based therapeutic vaccine has recently been developed for treating chronic HBV infection. In this review, we will discuss about the concept, scientific logics, strategies and techniques of development of HBV-specific immune therapies including vaccine therapy and dendritic cell-based vaccine therapy for treating chronic HBV infection.

The inverse association between the presence of antibody to hepatitis B surface antigen and atopy in young adults

BACKGROUND

Some bacterial and viral infections may reduce the risk of atopy, and this is based on the concept of their ability to divert the immune system towards the Th1 responses. Most of the hepatitis B virus (HBV) infections occur in the developing countries and this is where atopic disorders are least prevalent. Th1 responses are important for the viral clearance of HBV and also for antibody production. The aim of the study is to investigate whether the presence of antibodies to the hepatitis B surface antigen (anti-HBs) is inversely associated with atopy in adults.

METHODS

A random sample of 358 subjects, who were without hepatitis B surface antigen, was recruited; they were aged from 18 to 79 years (105 young adults aged <40 years and 253 older adults aged > 40 years). Determinations of the anti-HBs and skin prick tests using aeroallergens were performed. Those subjects with one or more positive skin reactions (a mean wheal diameter 23 mm) were considered atopic.

RESULTS

The prevalence rate of atopy (p=0.035) or the sensitization to Dermatophagoides farinae (p=0.01) was significantly lower in the subjects with anti-HBs than in those subjects without anti-HBs for the young adults, but not for the older adults. The logistic regression analysis that was done on the young adults showed that the presence of anti-HBs was associated with a significantly lower risk of atopy (the odds ratio adjusted for confounding variables = 0.40 [95% CI 0.16-0.981, p=0.046) or with the sensitization to D. farinae (0.20 [0.06-0.65], p = 0.008).

CONCLUSION

The presence of anti-HBs produced by a natural HBV infection or vaccination might be inversely associated with atopy in young adults.

Production of hepatitis B surface antigen-pulsed dendritic cells from immunosuppressed murine hepatitis B virus carrier: evaluation of immunogenicity of antigen-pulsed dendritic cells in vivo

Vaccines containing hepatitis B surface antigen (HBsAg) induce antibody to HBsAg (anti-HBs) in most normal individuals and protects them from hepatitis B virus (HBV) infection. However, these vaccines are not efficient at inducing anti-HBs in immunosuppressed individuals, especially in immunosuppressed HBV carriers. The aim of this study was to prepare and to assess the efficacy of a dendritic cell (DC)-based vaccine in an immunosuppressed HBV transgenic mouse (HBV-Tg), an animal model of the HBV carrier state. In order to prepare immunosuppressed HBV-Tg, HBV-Tg were injected with FK-506, an immunosuppressive agent, once daily, intraperitoneally for 15 days. Spleen cells of immunosuppressed HBV-Tg expressed very little mRNAs for interleukin-2 and interferon-gamma. DCs were isolated from the spleen of immunosuppressed HBV-Tg and cultured with HBsAg (100 microg) for 48 h to prepare HBsAg-pulsed DCs. Immunosuppressed HBV-Tg expressing HBsAg in the sera were administered with HBsAg-pulsed DCs or unpulsed DCs or HBsAg in adjuvant for different durations. Immunosuppressed HBV-Tg (n = 8) twice administered with HBsAg-pulsed DCs expressed anti-HBs in the sera within 6 weeks of first injection. Seven of eight immunosuppressed HBV-Tg remained positive for anti-HBs in the sera for the next 12 weeks of observation in spite of receiving daily injection of FK-506 for the entire duration. However, immunosuppressed HBV-Tg administered with unpulsed DCs or HBsAg in adjuvant did not express anti-HBs in the sera. The data show that DCs from immunosuppressed HBV-Tg can be loaded with HBsAg to prepare immunogenic HBsAg-pulsed DCs. HBsAg-pulsed DCs induced anti-HBs in immunosuppressed HBV-Tg. This approach may be of use to induce and maintain anti-HBs in immunosuppressed human HBV carriers.

Impaired functional capacities of liver dendritic cells from murine hepatitis B virus (HBV) carriers: relevance to low HBV-specific immune responses

The chronic hepatitis B virus (HBV) carrier exhibits ongoing replication of HBV and expresses abundant amounts of HBV-related antigens in the liver. However, HBV-specific immune responses are either absent or narrowly focused in these subjects. With the postulation that impaired functional abilities of liver dendritic cells (DCs) might be responsible for this, we assessed the functions of liver DCs in HBV transgenic mice (HBV-TM), an animal model of the HBV carrier state. Liver DCs were isolated from normal C57BL/6 mice and HBV-TM without the use of cytokines or growth factors. Lymphoproliferative assays were conducted to evaluate the ability of liver DCs to induce the proliferation of allogenic T lymphocytes and hepatitis B surface antigen (HBsAg)-enriched T lymphocytes. Liver DCs were stimulated with viral and bacterial products to assess their cytokine-producing capacities. In comparison to liver DCs from normal C57BL/6 mice, liver DCs from HBV-TM exhibited significantly decreased T cell proliferation-inducing capacities in allogenic mixed leucocyte reaction (P <0.05) and HBsAg-enriched T lymphocytes proliferation assays (P <0.05). Liver DCs from HBV-TM produced significantly lower levels of interleukin-12p70, tumour necrosis factor-alpha, interferon-gamma, and interleukin-6 (P <0.05) compared to liver DCs from normal C57BL/6 mice. This study provides evidence that liver DCs from HBV-TM had impaired ability to induce both innate and adaptive immune responses. This might account for a weak and almost undetectable HBV-specific immune response in chronic HBV carriers. This inspires hope that up-regulation of the functions of liver DCs in situ may have therapeutic implications in chronic HBV carriers.

Isolation and functional analysis of circulating dendritic cells from hepatitis C virus (HCV) RNA-positive and HCV RNA-negative patients with chronic hepatitis C: role of antiviral therapy

Hepatitis C virus (HCV) RNA has been localized in antigen-presenting dendritic cells (DCs) from patients with chronic hepatitis C (CHC). DCs from patients with CHC also exhibit impaired functional capacities. However, HCV RNA in DCs and functional impairment of DCs in CHC might be independent or interrelated events. Moreover, the impact of antiviral therapy on the functions of DCs in CHC is not well documented. In order to address these issues, we took advantage of antiviral therapy in these patients. Ten patients with CHC, expressing HCV RNA in circulating DCs, became negative for HCV RNA in circulating DCs after therapy with interferon-alpha and ribavirin for 4 weeks. The functions of DCs from HCV RNA+ patients (isolated before antiviral therapy) and HCV RNA- patients (isolated 4 weeks after antiviral therapy) were compared in allogenic mixed leucocyte reactions. In comparison to circulating DCs from normal control subjects, DCs from HCV RNA+ patients had a significantly decreased capacity to stimulate allogenic T lymphocytes (P < 0.01) and produce interleukin-12 (P < 0.05). However, the allostimulatory capacity of circulating DCs from HCV RNA- patients was several-fold higher compared to that of HCV RNA+ DCs from the same patient. DC from HCV RNA- patients also produced significantly higher levels of interleukin-12 compared to HCV RNA+ DCs from the same patient (P < 0.01). Taken together, this study is the first to provide experimental evidence regarding the impact of HCV RNA and antiviral therapy on the function of DCs in patients with CHC.

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Cytokine-dependent anti-viral role of CD4-positive T cells in therapeutic vaccination against chronic hepatitis B viral infection

There are several lines of evidence suggesting that specific vaccine therapy with a standard hepatitis B virus (HBV) vaccination reduces HBV replication. The aim of this study was to investigate the anti-viral mechanism of vaccine therapy in chronic hepatitis B patients. Nineteen patients were assigned to receive either vaccine therapy (n = 13) or no treatment as a control (n = 6). Vaccinated patients were analyzed for T cell proliferative responses specific for envelope antigen and cytokine production by antigen-specific T cells. ELISPOT and cytotoxicity assays also were carried out for limited blood samples. Serum HBV DNA levels decreased significantly at 3 months after completion of therapy and thereafter as compared to the baseline ones, and were significantly lower in vaccinated patients than in controls at 12 and 18 months after completion of therapy. Vaccination induced antigen-specific CD4+ T cell proliferative responses in four patients (30.8%). The production of high levels of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) by antigen-specific T cells was found in six patients (46.0%) who showed significantly lower HBV DNA levels in serum at 6 (P = 0.04) and 18 months (P = 0.005) after completion of therapy than those without high levels of cytokine production. Vaccination did not induce antigen-specific CD8+ T cells or cytotoxic T cells. These results suggest that envelope-specific CD4+ T cells may control directly HBV replication by producing anti-viral cytokines rather than providing help for cytotoxic T cells in therapeutic vaccination against chronic HBV infection.

The lack of effect of therapeutic vaccination with a pre-S2/S HBV vaccine in the immune tolerant phase of chronic HBV infection

BACKGROUND/AIMS

Even if the results are controversial and preliminary, several reports suggest that the HBV vaccine might be effective in treating HBV infection. In this study, we aimed to evaluate the efficacy and safety of specific anti-HBV vaccination for the immune tolerance phase of chronic HBV infection in a randomized, controlled study.

PATIENTS AND METHODS

The 47 subjects included patients that were treatment-naive with hepatitis B e antigen positivity, active hepatitis B virus replication as measured by hepatitis B virus DNA levels, persistently normal alanine transaminase levels, and with minimal or absent disease activity by liver biopsy. Thirty patients were given three intramuscular injections of 20 micro g of a pre-S2/S vaccine (GenHevac-B) on days 0, 30, and 60, and the remaining 17 patients were included in the control group. The efficacy of vaccination was evaluated by testing for loss of serum HBV DNA or decrease in its level and for HBeAg seroconversion. A significant decrease in HBV DNA levels was accepted as a decrease of >50% of initial values. The complete response was defined as loss of HBV DNA in serum with HBeAg seroconversion. Postvaccination follow-up lasted 12 months after the first dose.

RESULTS

No significant effects were observed in the vaccination population in the reduction of HBV DNA to undetectable levels, or to <50% of prevaccination levels, in HBeAg/anti-HBe seroconversion, or in transaminase levels. There was an early clearance/decrease in HBV DNA levels in five vaccinated patients by 3 months, and none in controls (P = 0.143), and two of them had sustained responses later. At the end of follow-up, complete response is almost similar in study as well as control group (13% vs. 12%, P > 0.05). Disappearance of serum HBV DNA was more frequently observed in those patients who had pretreatment viremia of <100 pg/mL in both groups. The median levels of HBV DNA and alanine transaminase activity between baseline and 12 months did not differ significantly in both groups. All patients remained HBsAg positive and none developed anti-HBs. No serious adverse event was encountered in vaccinated patients, and the therapy was well tolerated. Follow-up lasted a median of 16 months (range 12-30 months) for the study group and 18 months (range 12-31months) for the control group.

CONCLUSIONS

Immunotherapy with specific anti-HBV vaccine in the immune tolerance phase of chronic HBV infection did not offer additional benefit. New immunotherapeutic strategies to control HBV infection by specific HBV vaccines in chronically infected subjects are needed.

Detection of T lymphocyte subsets and mIL-2R on surface of PBMC in patients with hepatitis B

AIM: To study the levels of T lymphocyte subsets and membrane interleukin-2 receptor (mIL-2R) on surface of peripheral blood mononuclear cells (PBMCs) of patients with hepatitis B and its role in the pathogenesis of hepatitis B.

METHODS: The levels of T lymphocyte subsets and mIL-2R in PBMC before and after being stimulated with PHA were detected by biotin-streptavidin (BSA) technique in 196 cases of hepatitis B.

RESULTS: In patients with hepatitis B, the levels of CD₃⁺, CD₄⁺ cells, and the ratio of CD₄⁺ cells/CD₈⁺ cells were lower, but the level of CD₈⁺ cells was higher than those in normal controls (42.20 ± 6.01 vs 65.96 ± 6.54, 38.17 ± 5.93 vs 41.73 ± 6.40, 0.91 ± 0.28 vs 1.44 ± 0.31, 39.86 ± 6.36 vs 30.02 ± 4.54, P < 0.01). The total expression level of mIL-2R in PBMC before and after being stimulated with PHA was also lower than those in normal controls (3.47 ± 1.55 vs 4.52 ± 1.49, 34.03 ± 2.94 vs 37.95 ± 3.00, P < 0.01). In all the patients with hepatitis B, the levels of T lymphocyte subsets and mIL-2R in PBMC with HBV-DNA (+) were lower than those with HBV-DNA (-), which were significantly different (39.57 ± 7.11 vs 44.36 ± 5.43, 34.36 ± 7.16 vs 40.75 ± 5.87, 37.82 ± 6.54 vs 41.72 ± 6.21, 0.88 ± 0.33 vs 0.99 ± 0.27, 2.82 ± 1.62 vs 3.85 ± 1.47, 31.56 ± 3.00 vs 35.84 ± 2.83, P < 0.01). In addition, the levels of CD₃⁺, CD₄⁺, CD₈⁺ cells, the ratio of CD₄⁺ cells/CD₈⁺ cells and mIL-2R among different courses of hepatitis B were all significantly different (F = 3723.18, P < 0.01. F = 130.43, P < 0.01. F = 54.01, P < 0.01. F = 2.99, P < 0.05. F = 7.16, P < 0.01).

CONCLUSION: Both cellular and humoral immune functions are obviously in disorder in patients with hepatitis B, which might be closely associated with the chronicity in patients.

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Defective antigen-presenting capacity of murine dendritic cells during starvation

Significant impairments of several aspects of immunity have been described in acute and chronic nutritional deficiencies; however, there have been few studies on antigen-presenting cells during starvation. We examined the antigen-presenting capacities of mouse dendritic cells (DCs) from lymphoid organ (spleen DCs) and non-lymphoid tissue (liver DCs) during starvation. The total numbers of spleen DCs and liver DCs were significantly fewer in starved mice than in control mice. Functional analysis showed that the proliferative activities of spleen DCs and liver DCs were significantly impaired in starved mice compared with control mice. In particular, liver DCs from starved mice were unable to induce interferon-gamma. Liver DCs from starved mice were unable to induce proliferation of antigen-specific memory lymphocytes. These data indicated that one major cause of impairment of immunologic responses during starvation may be mediated through DCs.

Clinical and immunological efficacy of intradermal vaccine plus lamivudine with or without interleukin-2 in patients with chronic hepatitis B

To evaluate therapeutic immunostimulation nine chronic hepatitis B patients received six monthly intradermal vaccinations with HBsAg in combination with daily lamivudine. Another five patients received six doses of the vaccine and daily lamivudine together with daily Interleukin-2 (IL-2) s.c. within 3 months in an open-labeled trial. Clinical efficacy was assessed by alanine transaminase levels and HBV serology. The induction of specific T and B cell responses was analyzed serially by 3H-thymidine uptake, ELISA and ELISPOT assays. After the therapy was stopped, seven of nine vaccine/lamivudine and two of five vaccine/lamivudine/IL-2 recipients did not have detectable HBV DNA. Four complete responders cleared the virus and had normalized ALT levels, however, one of these patients showed transient disease reactivation followed by spontaneous viral clearance and normal ALT five months later. Low frequencies of anti-HBs producing B cells and HBV specific T helper cells secreting predominantly interferon-gamma were induced by i.d. vaccine therapy. The ELISPOT technique demonstrated transient induction of HBV peptide specific cytotoxic T cells in seven HLA-A2 positive chronic HBV carriers. The preliminary data from this study demonstrate that the HBV surface antigen vaccine in combination with antiviral or immunomodulating drugs induced antiviral immune responses and consequently viral elimination may be achieved in patients with unfavorable prognosis.

Immunobiology of liver dendritic cells

Dendritic cells (DC) are rare, bone marrow-derived antigen-presenting cells that play a critical role in the induction and regulation of immune reactivity. In this article, we review the identification and characterization of liver DC, their ontogenic development, in vivo mobilization and population dynamics. In addition, we discuss the functions of DC isolated from liver tissue or celiac lymph, or propagated in vitro from liver-resident haemopoietic stem/progenitor cells. Evidence concerning the role of DC in viral hepatitis, liver tumours, autoimmune liver diseases, granulomatous inflammation and the outcome of liver transplantation is also discussed.

Therapeutic vaccination in chronic hepatitis B

AIMS

The aim was to test the efficacy of a pre-S2-containing vaccine (Genhevac-B) in chronic hepatitis B (CHB). Twenty-five naive patients (22 male, three female; median age 35; range: 6-69 years) with CHB were recruited. The inclusion criteria were: hepatitis B e antigen (HBeAg) positive or HBV-DNA detectable with liquid hybridization; alanine aminotransferase (ALT) is at least 1.5-fold the upper normal limit and histological evidence of chronic hepatitis.

METHODS

In the first period, all patients received monthly injections of 20, 40 and 60 microg of the vaccine. One month after the last injection, patients who still had HBV-DNA were divided into two randomly assigned groups. While the patients in the first group and the patients who lost HBV-DNA in the first period continued to receive monthly injections of 20 microg vaccine for a further 6 months, the patients in the second group received 9 MU interferon alpha-2b (Roferon-A), three times per week using the same method as for the first group. Patients were followed up after 12 months without treatment. Response was defined as the loss of HBV-DNA and normalization of ALT.

RESULTS

Six of the 25 patients lost HBV-DNA after 3 months. Nine of the remainder were randomly placed in the first group (vaccine-only) and 10 were placed in the second group (vaccine + interferon). End-of-treatment response was achieved, overall, 8/15 from the vaccine group and 6/10 from the combination. One patient from each group relapsed during the follow up. Overall, the sustained response (SR) rate was 46% (7/15) in the vaccine group, and 50% (5/10) in the combination group. Histological improvement was achieved in 6/7 SR with vaccine-only and all five with combination treatment, while 1/8 of failures of vaccine and 2/5 of failures of combination improved.

CONCLUSIONS

It was concluded that Genhevac-B decreases serum HBV-DNA levels in the majority of patients with CHB and sustained clearance was achieved in some patients. Combination of interferon-alpha with Genhevac-B is effective for the vaccine failures and may increase sustained response compared to interferon-alpha alone. However, the mechanism of action is yet to be explained.

Do hepatitis B virus carriers develop atopic diseases?

The prevalence of allergic disorders, such as asthma, hay fever, and atopic dermatitis, has increased dramatically over the past few decades. Although the important inherited component in these diseases is well established, the role of environmental factors in relation to allergic disorders has become increasingly topical in the last decade. Immunologic data show that different infections can either promote atopy (as in respiratory syncytial virus infections) or inhibit it (as in measles, hepatitis A, and tuberculosis). Although there are 400 million hepatitis B virus (HBV) carriers around the world, and asymptomatic HBV carriers with a high level of virus replication are characterized by Th2-type immune reactions, the relationship between HBV carriers and atopic disorders has not been studied.

Dysfunction of peripheral blood dendritic cells from patients with chronic hepatitis B virus infection

AIM: To identify the property of dendritic cells (DCs) of peripheral blood monocytes (PBMC) in patients with chronic HBV infection.

METHODS: Twenty patients with persistent HBV infection were included in this study, 10 healthy subjects being used as a control group. The peripheral blood mononuclear cells (PBMC) of T cell-depleted populations were incubated and induced into mature dendritic cells in the RPMI-1640 medium in the presence of cytokines GM-CSF, IL-4, FLt-3, TNF-α and 100 mL·L^-1 of fetal calf serum for a total of 10-12 d. The expressions of surface markers on DCs were evaluated using flow cytometric analysis. ELISA method was used to determine the cytokine levels of interleukin-12 (IL-12) and IL-10 in the supernatant produced by DCs. For detection of the stimulatory capacity of DCs to T cell proliferation, mytomycin C-treated DC were incubated with allogenic T cells.

RESULTS: A typical morphology of mature DCs from healthy subjects and HBV-infected patients was induced in in vitro incubation, but the proliferation ability and cellular number of DCs from HBV-infected patients significantly decreased compared with healthy individuals. In particular, the expression levels of HLA-DR, CD80 (B7-1) and CD86 (B7-2) on DC surface from patients were also lower than that from healthy individuals (0.46 vs 0.92 for HLA-DR, 0.44 vs 0.88 for CD80 and 0.44 vs 0.84 for CD86, P < 0.05). The stimulatory capacity and production of IL-12 of DCs from patients in allogenic mixed lymphocyte reaction (AMLR) significantly decreased, but the production level of nitric oxide (NO) by DCs simultaneously increased compared with healthy subjects (86 ± 15 vs 170 ± 22 μmol·L^-1, P < 0.05).

CONCLUSION: The patients with chronic HBV infection have the defective function and immature phenotype of dendritic cells, which may be associated with the inability of efficient presentation of HBV antigens to host immune system for the clearance of HBV.

Peripheral blood T-cell responses to pyruvate dehydrogenase complex in primary biliary cirrhosis: role of antigen-presenting dendritic cells

Patients with primary biliary cirrhosis (PBC) are usually characterized by the presence of antibody to pyruvate dehydrogenase complex (PDC) in the sera and PDC-specific T cells in the liver. However, most of the patients with PBC do not show peripheral blood T cells response to PDC. In this study, we re-evaluated the peripheral blood T cell responses to PDC in PBC using antigen-presenting dendritic cells (DCs). Twenty-four patients with PBC (AMA-positive: 16; AMA-negative: 8) and 13 normal controls were enrolled in the study. Peripheral blood mononuclear cells (PBMC) and highly enriched populations of T cells were stimulated with either only PDC or DCs plus PDC or PDC-pulsed DC plus PDC. Antibodies to different components of PDC were estimated by an immunoblotting technique. PBMC from only one out of ten AMA-positive PBC patients proliferated when cultured with only PDC. However, peripheral blood T cells from ten out of ten AMA-positive PBC patients and three out of ten AMA-negative PBC patients, but none of the five normal controls showed PDC-specific proliferation when cultured with PDC-pulsed DCs. Two of these three AMA-negative PBC patients, although negative for AMA, were positive for antibodies to other components of PDC. PDC-specific T cells are present in the peripheral blood from most of the patients with PBC. This is the first report on the effectiveness of antigen-pulsed DCs for the elucidation of autoantigen-specific immune response in human autoimmune diseases.

Mechanism and therapeutic potential of DNA-based immunization against the envelope proteins of hepatitis B virus in normal and transgenic mice

Two plasmid DNA vectors, pCAGGS(S) encoding the genes of the major envelope protein of hepatitis B virus (HBV), and pCAGGS(S + preS2) encoding the genes of the middle envelope protein were used to study the mechanism and therapeutic potential of DNA-based immunization. Injection of these plasmids into the regenerating bilateral tibialis anterior muscle (TA) of normal C57BL/6 mice induced hepatitis B surface antigen (HBsAg)-specific humoral and cellular immune responses. Seventy-two hours after injection of pCAGGS(S), infiltrating cells including antigen-presenting dendritic cells (DC) were localized around the injection site and HBsAg was expressed by both muscle cells and infiltrating cells. Spleen DC from the mice were exposed to HBsAg for up to 32 weeks after a single injection of pCAGGS(S), because these DC induced the proliferation of HBsAg-specific memory lymphocytes in culture without exogenous HBsAg. A single injection of pCAGGS(S) or pCAGGS(S + preS2) resulted in the clearance of HBsAg in 28 out of 30 HBV-transgenic (Tg) mice. In contrast, more than 7 monthly injections of an HBsAg-based vaccine were required for the clearance of HBsAg in 6 out of 29 HBV-Tg mice. Infiltrating DC at the DNA vaccine injection site may have a role in initiating HBsAg-specific immune response, whereas the persistence of HBsAg exposed spleen DC may contribute to long-lasting immunity. This study also suggested that DNA-based vaccines may be a potent tool for treating chronic HBV carriers.

Induction of cytokine production and proliferation of memory lymphocytes by murine liver dendritic cell progenitors: role of these progenitors as immunogenic resident antigen-presenting cells in the liver

BACKGROUND/AIMS

Many pathogenic organisms, including hepatotrophic viruses enter the liver and induce an immune response, but there is little information about the immunogenic resident antigen-presenting cells. The aim of this study was to determine whether dendritic cells in the liver are immunogenic antigen-presenting cells.

METHODS

Liver dendritic cell progenitors were enriched from normal C57BL/6 mice by culturing non-parenchymal cells with granulocyte-macrophage colony stimulating factor for 7 days. Then the surface antigen (MHC class II, CD86) expression, endocytic capacity, ability to induce cytokines, and the proliferation of memory lymphocytes were investigated.

RESULTS

Freshly enriched liver dendritic cell progenitors exhibited an immature phenotype and failed to stimulate allogenic T cells. However, the progenitors underwent maturation following exposure to antigens such as hepatitis B surface antigen and keyhole limpet hemocyanin. The progenitors then became strong stimulators of allogenic T cells, supported the production of interleukin-12 and interferon-gamma, and induced the proliferation of antigen-specific memory lymphocytes.

CONCLUSIONS

Dendritic cell progenitors are immunogenic resident antigen-presenting cells in the liver. Simultaneous investigation of both tolerogenic and immunogenic resident antigen-presenting cells may provide insights into the pathogenesis of persistent infection and autoimmmune diseases of the liver.

Therapy of chronic hepatitis B virus infection: inhibition of the viral polymerase and other antiviral strategies

Chronic hepatitis B infection remains a major public health problem worldwide. The hepatitis B virus belongs to the family of hepadnaviruses that replicate their DNA genome via a reverse transcription pathway. The chronicity of infection in infected hepatocytes is maintained by the persistence of the viral covalently closed circular DNA. The main strategies to combat chronic HBV infection rely on the stimulation of the specific antiviral immune response and on the inhibition of viral replication. While the prolonged administration of reverse transcriptase inhibitors is most often associated with a control of viral replication rather than eradication, it may select for resistant mutants. The search for new viral targets is therefore mandatory to design combination strategies to prevent the emergence of resistant mutants and eventually clear viral infection.

Potent synergistic effect of sho-saiko-to, a herbal medicine, during vaccine therapy in a murine model of hepatitis B virus carrier

BACKGROUND

Traditional herbal medicine, sho-saiko-to (TJ-9), improves subjective symptoms, and a recently developed vaccine therapy reduces the viral replication in some chronic hepatitis B virus (HBV)-carriers. The study presented here considers the impact of a combination of vaccine therapy and TJ-9 and the mechanism underlying the therapeutic effect of TJ-9.

MATERIALS AND METHODS

HBV-transgenic mice (HBV-Tg) expressing similar levels of HBV-related antigens and HBV DNA were used as an animal model of HBV-carrier state, and were assigned to receive either a TJ-9-enriched diet or a monthly injection of vaccine containing hepatitis B surface antigen (HBsAg), or both, for 12 consecutive months.

RESULTS

Twelve months after starting the therapy, 9% (1 of 11), 61% (11 of 18), and 100% (10 of 10) of HBV-Tg receiving only the TJ-9-treatment, only the monthly vaccine, and both the TJ-9 and vaccine, respectively, responded to therapy and became completely negative for HBsAg. Spleen lymphocytes and antigen presenting cells (APC) from TJ-9-treated HBV-Tg produced significantly higher levels of IgM, IgG and antibodies to keyhole limpet hemocyanin (KLH) and showed significantly higher stimulatory capacity in allogenic mixed leukocyte reaction (MLR) compared with the spleen cells and APC from HBV-Tg receiving normal diet without TJ-9 (P < 0.05).

CONCLUSION

These data confirm the therapeutic role of TJ-9 during HBV infection and inspire optimism of a widespread use of TJ-9 during immune therapies.