Ablation of persistent hepatitis B by bone marrow transplantation from a hepatitis B-immune donor

Preclinical evaluation of therapeutic vaccines for chronic hepatitis B that stimulate antiviral activities of T cells and NKT cells

Background & Aims

Liver diseases resulting from chronic HBV infection are a significant cause of morbidity and mortality. Vaccines that elicit T-cell responses capable of controlling the virus represent a treatment strategy with potential for long-term effects. Here, we evaluated vaccines that induce the activity of type I natural killer T (NKT) cells to limit viral replication and license stimulation of conventional antiviral T-cells.

Methods

Vaccines were prepared by conjugating peptide epitopes to an NKT-cell agonist to promote co-delivery to antigen-presenting cells, encouraging NKT-cell licensing and stimulation of T cells. Activity of the conjugate vaccines was assessed in transgenic mice expressing the complete HBV genome, administered intravenously to maximise access to NKT cell-rich tissues.

Results

The vaccines induced only limited antiviral activity in unmanipulated transgenic hosts, likely attributable to NKT-cell activation as T-cell tolerance to viral antigens is strong. However, in a model of chronic hepatitis B involving transfer of naive HBcAg-specific CD8+ T cells into the transgenic mice, which typically results in specific T-cell dysfunction without virus control, vaccines containing the targeted HBcAg epitope induced prolonged antiviral activity because of qualitatively improved T-cell stimulation. In a step towards a clinical product, vaccines were prepared using synthetic long peptides covering clusters of known HLA-binding epitopes and shown to be immunogenic in HLA transgenic mice. Predictions based on HLA distribution suggest a product containing three selected SLP-based vaccines could give >90 % worldwide coverage, with an average of 3.38 epitopes targeted per individual.

Conclusions

The novel vaccines described show promise for further clinical development as a treatment for chronic hepatitis B.

Impact and Implications

Although there are effective prophylactic vaccines for HBV infection, it is estimated that 350-400 million people worldwide have chronic hepatitis B, putting these individuals at significant risk of life-threatening liver diseases. Therapeutic vaccination aimed at activating or boosting HBV-specific T-cell responses holds potential as a strategy for treating chronic infection, but has so far met with limited success. Here, we show that a glycolipid-peptide conjugate vaccine designed to coordinate activity of type I NKT cells alongside conventional antiviral T cells has antiviral activity in a mouse model of chronic infection. It is anticipated that a product based on a combination of three such conjugates, each prepared using long peptides covering clusters of known HLA-binding epitopes, could be developed further as a treatment for chronic hepatitis B with broad global HLA coverage.

CD4+ T Cells in Chronic Hepatitis B and T Cell-Directed Immunotherapy

The impaired T cell responses observed in chronic hepatitis B (HBV) patients are considered to contribute to the chronicity of the infection. Research on this impairment has been focused on CD8⁺ T cells because of their cytotoxic effector function; however, CD4⁺ T cells are crucial in the proper development of these long-lasting effector CD8⁺ T cells. In this review, we summarize what is known about CD4⁺ T cells in chronic HBV infection and discuss the importance and opportunities of including CD4⁺ T cells in T cell-directed immunotherapeutic strategies to cure chronic HBV.

A prospective trial of vaccine to prevent hepatitis B virus reactivation after hematopoietic stem cell transplantation

Hepatitis B virus (HBV) reactivation reportedly occurs frequently after hematopoietic stem cell transplantation (HSCT) in resolved HBV-infected patients. Here, 50 patients with resolved HBV infections and scheduled to undergo HSCT were enrolled; all subjects were vaccinated with three doses of hepatitis B vaccine 12 months after HSCT and the incidence of HBV reactivation was monitored. The patients' characteristics were: median age, 61 (34-72) years; male/female, 27/19; allogeneic/autologous, 40/6; bone marrow/peripheral blood stem cells/cord blood, 26/16/4. Of the 46 patients who underwent HSCT, 19 were excluded and did not make it to vaccination due to relapse of underlying disease, HBV reactivation within 12 months of HSCT, or transfer of patients. The remaining 27 were vaccinated 12 months after HSCT and monitored for 2 years. Six showed HBV reactivation, with a 2-year cumulative reactivation incidence of 22.2%; the same incidence was 27.3% only in allogeneic HSCT patients. Factors associated with HBV reactivation included the discontinuation of immunosuppressants (P = 0.0379) and baseline titers of antibody against hepatitis B surface antigen (P = 0.004). HBV reactivation with vaccination following HSCT could occur despite maintenance of serum anti-HBs at more than protective levels.

New treatments to reach functional cure: Rationale and challenges for emerging immune-based therapies

The landscape for chronic HBV therapy is rapidly evolving. The latest generation of antiviral drugs provide robust virus suppression with a high barrier to resistance that facilitates long-term treatment. However, low rates of HBsAg loss demonstrate that additional strategies are needed to consistency achieve a functional cure. The immune system can clear HBV and establish long-term control over the virus. Sufficiently boosting HBV immunity in chronic patients has been very difficult due to immune exhaustion, immune dysregulation, and inhibitory pathways suppressing the immune response. Therapeutic vaccines employing new technology, vectors and new immunomodulatory drugs that can elicit direct antiviral effects and cancel inhibitory mechanism may be able to overcome exhaustion. This review will discuss the justification for immunotherapy, lessons from previous trials and new vaccines/drugs in early stage clinical trials. The challenges of correlating immune responses induced by these drugs to clinical efficacy will also be addressed.

Hepatitis B Virus Replication in CD34+ Hematopoietic Stem Cells From Umbilical Cord Blood

BACKGROUND Hepatitis B virus (HBV) is a hepatotropic virus that can infect extrahepatic tissue. Whether hematopoietic stem cells (HSCs) can be infected by HBV and serve as a potential virus reservoir is still unknown. In this study, the susceptibility of CD34+ HSCs to HBV was investigated. MATERIAL AND METHODS Cord blood-derived CD34+ HSCs were exposed to HBV in vitro, and immunocytochemistry, transmission electron microscopy, and RT-PCR were used to identify viral-related proteins and specific viral genomic sequences. Then, CD34+ HSCs were challenged by different titers of HBV, and intracellular and supernatant HBV DNA, and hepatitis B surface antigen (HBsAg) levels, were examined. In addition, CD34+ peripheral blood stem cells (PBSCs) from chronic HBV carriers were isolated and cultured, and HBV DNA levels were measured. RESULTS HBV-infected CD34+ cells showed positive signals for HBsAg by DAB staining and TRITC staining, and HBV particles were identified. RT-PCR results showed that the 403 bp PCR products corresponding to the amplified hepatitis B S gene fragment were observed in CD34+ HSCs infected by HBV. In addition, supernatant and intracellular HBV DNA increased with the proliferation of CD34+ HSCs. Similar results were obtained from intracellular HBsAg quantification tests. In addition, HBV DNA levels both in cells and in supernatants of CD34+ PBSCs increased proportionally, and the increments of HBV DNA in the supernatants paralleled those found in cells. CONCLUSIONS HBV can replicate in CD34+ HSCs in cord blood or peripheral blood of chronic HBV carriers.

Prevention and Treatment of Recurrent Hepatitis B after Liver Transplantation

Chronic hepatitis B is a global health problem that leads to development of various complications, such as cirrhosis, liver cancer, and liver failure requiring liver transplantation. The recurrence of hepatitis B virus (HBV) post-liver transplantation is a major cause of allograft dysfunction, cirrhosis of the allograft, and graft failure. Patients with high viral load at the time of transplantation, hepatitis B e antigen (HBeAg) positivity, or those with a history of anti-viral drug resistance are considered as high-risk for recurrent HBV post-liver transplantation, while patients with low viral load, including HBeAg negative status, acute liver failure, and hepatitis D virus (HDV) co-infection are considered to be at low-risk for recurrent HBV post-liver transplantation. Antivirals for patients awaiting liver transplantation(LT) cause suppression of HBV replication and reduce the risk of recurrent HBV infection of the allograft and, therefore, all HBV patients with decompensated cirrhosis should be treated with potent antivirals with high genetic barrier to resistance (entecavir or tenofovir) prior to liver transplantation. Prevention of post-liver transplantation recurrence should be done using a combination of hepatitis B immunoglobulin (HBIG) and antivirals in patients at high risk of recurrence. Low dose HBIG, HBIG-free protocols, and monoprophylaxis with high potency antivirals can still be considered in patients at low risk of recurrence. Even, marginal grafts from anti-HBc positive donors can be safely used in hepatitis B surface antigen (HBsAg) negative, preferably in anti-hepatitis B core (HBc)/anti-hepatitis B surface (HBs) positive recipients. In this article, we aim to review the mechanisms and risk factors of HBV recurrence post-LT in addition to the various treatment strategies proposed for the prevention of recurrent HBV infection.

Enhanced immune response to hepatitis B vaccination through immunization with a Pre-S1/Pre-S2/S vaccine

Efficacy and safety of recombinant yeast-derived hepatitis B vaccines for prevention of hepatitis B have been demonstrated unequivocally worldwide as reflected in reduction in HBsAg carrier rates and hepatocellular carcinoma. A new generation of recombinant HBV vaccines expressed in mammalian cells containing Pre-S/S epitopes has been developed in several countries. Such vaccines are useful in special risk groups, i.e., in non-responders to conventional HBV vaccines including older adults, obese people, health care workers, patients with renal failure and on dialysis, transplant patients, patients with HIV as well as travelers on short notice to HBV endemic regions. The future of such vaccines depends on their enhanced immunogenicity and cost profile. Sci-B-Vac™ is a mammalian cell-derived recombinant Pre-S1/Pre-S2/S hepatitis B vaccine which has been shown to be highly immunogenic, inducing faster and higher seroprotection rates against HBV with higher anti-HBs levels at lower HBsAg doses as compared to conventional yeast-derived vaccines. Recently, it has been suggested that such Pre-S/S vaccines against HBV might be efficacious not only for prevention but also for intervention in persistent HBV infection. Data obtained in a recent clinical trial conducted in Vietnam in patients with chronic hepatitis B suggest that repeated monthly i.m. injections of the Sci-B-Vac™ co-administered with daily oral lamivudine treatment can suppress HBV replication and lead to anti-HBs seroconversion in ~50 % of treated patients. Optimization of protocols and efficacy of such an intervention, intended to bypass T cell exhaustion and immune tolerance to HBV remains to be explored.

Circumventing failed antiviral immunity in chronic hepatitis B virus infection: triggering virus-specific or innate-like T cell response?

Therapeutic vaccination for the treatment of chronic hepatitis B has thus far been unsatisfactory. In this review, we discuss potential new therapeutic vaccination strategies and other immunotherapeutic approaches that aim to achieve efficient restoration of HBV immunity in chronically infected patients.

Infected hematopoietic stem cells and with integrated HBV DNA generate defective T cells in chronic HBV infection patients

A weak T-cell response plays a key role in the persistence of hepatitis B virus (HBV) infection. We aimed to confirm that T-cell defects in patients with chronic HBV infection are associated with HBV DNA infection of bone marrow (BM) hematopoietic stem cells (HSCs). Using reverse transcription polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH), we observed the transcription of HBsAg coding genes and confirmed the integration of HBV DNA in CD34(+) BM HSCs from chronic HBV infection patients. T cells were generated by coculturing the HSCs with delta-like ligand 1-expressing OP9 (OP9-DL1) cells. The phenotypes of the T cells were then evaluated by flow cytometric (FACS) analysis on days 14 and 25. The results demonstrated that fewer CD3(+) TCRaβ(+) CD3(+) CD4(+) and CD4(+) CD8(+) T cells were generated from the HSCs of the patients than from the healthy controls, (P < 0.01) but the frequency of CD3(+) D8(+) T cells was not significantly different between the two group (P > 0.05). In contrast, CD4(+) CD25(+) T cells were more in the patient group than in healthy controls (P < 0.01) on both days 14 and 25. There were fewer CD3(+) CD4(+) /CD3(+) CD8(+) cells in the patient group than in the healthy control group on day 25 (P < 0.05). Less proliferation and lower levels of IL-2 and IFN- γ were also observed in the patient group compared with the control group (P < 0.05).These data suggest that HBV DNA infected and integrated into the BM HSCs from patients with chronic HBV infection and that these BM HSCs generated defective T cells.

An engineered non-toxic superantigen increases cross presentation of hepatitis B virus nucleocapsids by human dendritic cells

Virus like particles (VLPs) are potent immunogens capable of priming strong protective antibody responses due to their repetitive structural arrangement and affinity for specific B cell receptors. By contrast, T cell responses to VLPs can be weak due to inefficient uptake and processing by antigen presenting cells. We report here a novel strategy for increasing the T cell reactivity of a VLP, the nucleocapsid of hepatitis B virus, through covalent coupling of M1, an engineered form of the Streptococcal superantigen SMEZ2, that binds MHC II with high affinity but lacks its T cell mitogenic capability. M1:HBcAg conjugates bound to dendritic cells and were efficiently endocytosed into late endosomes. Human dendritic cells pulsed with M1:HBcAgs stimulated HBV-specific CD8⁺ T cells more effectively than cells pulsed with native capsids indicating that the modified VLP was more effectively cross presented by APCs. Coupling of M1 was also able to induce significantly greater reactivity of human CD4⁺ T cells specific for a common T-helper epitope. These studies indicate the potential of recombinant superantigens to act as flexible molecular adjuvants that can be incorporated into various subunit vaccine platforms leading to enhanced T cell reactivity in humans.

Advances in the management of viral infections

Viral infections are common in cancer patients. The risk and severity of infection are influenced by patient, disease, treatment, and viral factors. Severe viral infections are more likely to occur in treatment regimens that are more immunosuppressive. Historically, the most frequent severe infections have been due to herpesviruses, but more recently, other pathogens, especially community respiratory and hepatitis viruses, have received increasing attention as major viral pathogens in cancer patients. Because of the new diagnostic assays and the introduction of better therapeutic options, knowledge of viral infections is important in optimizing antineoplastic therapies.

Immune therapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third most common cause of cancer-related death worldwide. Currently, there are no treatment options available for a large number of these patients. One of the mechanisms that may contribute to tumor growth is the lack of an effective immune response toward viral antigens or other tumor-associated antigens (TAAs). Immunotherapy has been tested as a potential therapeutic option for these patients. Several methods of immune modulation for augmenting antitumor immunity are being explored and have been shown to be effective in suppressing HCC growth in animal models. Activation of HCC-specific response can be accomplished by targeting hepatitis B or C viral antigens, alpha-fetoprotein, or other TAAs. This review summarizes part of the recent data on the use of adoptive transfer of immunity against viral antigens, oral immune modulation against TAAs, and the use of pulsed innate immune cells and gut adjuvants for the suppression of HCC; it reviews some additional new immunotherapeutic approaches.

Prevention of recurrent hepatitis B infection after liver transplantation

BACKGROUND

Recurrence of hepatitis B virus (HBV) infection after liver transplantation can lead to graft loss and a reduction in long-term survival. The purpose of this review is to summarize the current therapeutic options for preventing HBV recurrence in liver transplant recipients.

DATA SOURCES

Up to January 2013, studies that were published in MEDLINE and EMBASE on prevention of HBV recurrence after liver transplantation were reviewed.

RESULTS

There have been remarkable advancements in the past two decades on the prevention of HBV recurrence after liver transplantation, from the discovery of hepatitis B immune globulin (HBIG) and lamivudine monotherapy to the combination therapy using HBIG and lamivudine. With the development of newer and stronger antiviral agents, the need for life-long HBIG is doubtful. With their low resistance profile, oral antiviral prophylaxis using these new agents alone is sufficient and is associated with excellent outcome.

CONCLUSIONS

Restoration of host HBV immunity with adoptive immunity transfer and vaccination may represent the ultimate strategy to withdraw prophylactic treatment and to achieve a drug free regimen against HBV recurrence after liver transplantation.

T cells expressing a chimeric antigen receptor that binds hepatitis B virus envelope proteins control virus replication in mice

BACKGROUND & AIMS

Antiviral agents suppress hepatitis B virus (HBV) replication but do not clear the infection. A strong effector T-cell response is required to eradicate HBV, but this does not occur in patients with chronic infection. T cells might be directed toward virus-infected cells by expressing HBV-specific receptors and thereby clear HBV and help to prevent development of liver cancer. In mice, we studied whether redirected T cells can engraft after adoptive transfer, without prior T-cell depletion, and whether the large amounts of circulating viral antigens inactivate the transferred T cells or lead to uncontrolled immune-mediated damage.

METHODS

CD8(+) T cells were isolated from mice and stimulated using an optimized protocol. Chimeric antigen receptors (CARs) that bind HBV envelope proteins (S-CAR) and activate T cells were expressed on the surface of cells using retroviral vectors. S-CAR-expressing CD8(+) T cells, which carried the marker CD45.1, were injected into CD45.2(+) HBV transgenic mice. We compared these mice with mice that received CD8(+) T cells induced by vaccination, cells that express a CAR without a proper signaling domain, or cells that express a CAR that does not bind HBV proteins (controls).

RESULTS

CD8(+) T cells that expressed HBV-specific CARs recognized different HBV subtypes and were able to engraft and expand in immune-competent HBV transgenic mice. After adoptive transfer, the S-CAR-expressing T cells localized to and functioned in the liver and rapidly and efficiently controlled HBV replication compared with controls, causing only transient liver damage. The large amount of circulating viral antigen did not impair or overactivate the S-CAR-grafted T cells.

CONCLUSIONS

T cells with a CAR specific for HBV envelope proteins localize to the liver in mice to reduce HBV replication, causing only transient liver damage. This immune cell therapy might be developed for patients with chronic hepatitis B, regardless of their HLA type.

Hepatitis B virus: from immunobiology to immunotherapy

Owing to the major limitations of current antiviral therapies in HBV (hepatitis B virus) infection, there is a strong need for novel therapeutic approaches to this major health burden. Stimulation of the host's innate and adaptive immune responses in a way that results in the resolution of viral infection is a promising approach. A better understanding of the virus-host interaction in acute and chronic HBV infection revealed several possible novel targets for antiviral immunotherapy. In the present review, we will discuss the current state of the art in HBV immunology and illustrate how control of infection could be achieved by immunotherapeutic interventions.

Living in the liver: hepatic infections

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

Engineering virus-specific T cells that target HBV infected hepatocytes and hepatocellular carcinoma cell lines

BACKGROUND & AIMS

Virus-specific T cells capable of controlling HBV and eliminating hepatocellular carcinoma (HCC) expressing HBV antigens are deleted or dysfunctional in patients with chronic HBV or HBV-related HCC. The goal of this study was to determine if T cell receptor (TCR) gene transfer can reconstitute HBV-specific T cell immunity in lymphocytes of chronic HBV patients and investigate whether HCC cells with natural HBV-DNA integration can be recognized by genetically modified T cells.

METHODS

We used vector-mediated gene transfer to introduce HLA-A2-restricted, HBV-specific TCRs into T cells of chronic HBV as well as HBV-related HCC patients.

RESULTS

The introduced TCRs were expressed on the cell surface, evidenced by Vβ and pentamer staining. TCR transduced T cells produced IFN-γ, TNF-α, IL-2, and lysed HBV infected hepatocyte-like cell lines. Furthermore, HCC cell lines with natural HBV-DNA integration could be recognized by HBV-specific TCR-re-directed T cells.

CONCLUSIONS

TCR re-directed HBV-specific T cells generated from PBMC of chronic HBV and HBV-related HCC patients were multifunctional and capable of recognizing HBV-infected cells and HCC tumor cells expressing viral antigens from naturally integrated HBV DNA. These genetically modified T cells could be used to reconstitute virus-specific T cell immunity in chronic HBV patients and target tumors in HBV-related HCC.

Therapeutic vaccines and immune-based therapies for the treatment of chronic hepatitis B: perspectives and challenges

The treatment of chronic hepatitis B virus (HBV) infection has greatly improved over the last 10 years, but alternative treatments are still needed. Therapeutic vaccination is a promising new strategy for controlling chronic infection. However, this approach has not been as successful as initially anticipated for chronic hepatitis B. General impairment of the immune responses generated during persistent HBV infection, with exhausted T cells not responding correctly to therapeutic vaccination, is probably responsible for the poor clinical responses observed to date. Intensive research efforts are now focusing on increasing the efficacy of therapeutic vaccination without causing liver disease. Here we describe new approaches to use with therapeutic vaccination, in order to overcome the inhibitory mechanisms impairing immune responses. We also describe innovative strategies for generating functional immune responses and inducing sustained control of this persistent infection.

Development of immunity against hepatitis B virus after donor lymphocyte infusion in a peripheral blood stem cell transplantation recipient with chronic hepatitis B

Hepatitis B virus (HBV) infection is one of the main concerns in blood and marrow transplantation (BMT) patients for possible breakthrough hepatitis. Active recipient immunization against HBV was found to be ineffective and many studies had showed that the adoptive transfer of immunity against hepatitis B virus would be possible by BMT with unknown duration and mechanism. A 46-year-old female patient with chronic hepatitis B had persistent detectable HBV DNA and positive serum hepatitis B e antigen (HBeAg), even while on long-term lamivudine and adefovir therapy. She received allogeneic matched unrelated donor peripheral blood stem cell transplantation (allo-MUD-PBSCT) for her refractory acute myeloid leukemia (AML). The HBV DNA became undetectable and she developed HBeAg seroconversion after PBSCT. Her hepatitis B surface antigen (HBsAg) remained positive, which disappeared later, along with the development of antibody to HBsAg after one shot of donor lymphocyte infusion (DLI) as a boost against her AML. In summary, BMT from an immunized donor would probably bring adoptive immunity against HBV. This adoptive immunity might be further enhanced by the subsequent DLI.

HBV life cycle and novel drug targets

With up to 400 million affected people worldwide, chronic hepatitis B virus (HBV) infection is still a major health care problem. During the last decade, several novel therapeutic approaches have been developed and evaluated. In most regions of the world, interferon-α, and nucleos(t)ide analogues (NUCs) are currently approved. Despite major improvements, none of the existing therapies is optimal since viral clearance is rarely achieved. Recently, a better understanding of the HBV life cycle and the development of novel model systems of HBV infection have led to the development of novel antiviral strategies and drug targets. This review will focus on current and potential future drug targets in the HBV life cycle and strategies to modulate the virus-host interaction.

The molecular basis of the failed immune response in chronic HBV: therapeutic implications

There is a pressing need to develop new immunotherapeutic interventions in chronic hepatitis B virus (HBV) infection in order to limit the high costs and risks of toxicity or viral resistance associated with maintenance antiviral treatment. Here we review recent advances in our understanding of the molecular defects underlying the profound T cell depletion characteristic of these patients. We propose that T cells are driven to apoptosis by the combination of a persistent, high antigen load and excessive inhibitory signals encountered in the hepatic microenvironment. The feasibility of boosting sustained antiviral control by targeted reversal of key tolerising mechanisms is discussed.

Therapeutic vaccination and novel strategies to treat chronic HBV infection

Therapeutic vaccination for the treatment of chronic hepatitis B has so far shown limited clinical efficacy. In this review, we argue that the principal cause of this failure is the profound defect of virus-specific T cells present in chronic hepatitis B patients and we discuss potential new ways to achieve an efficient restoration of virus-specific immunity in patients with chronic hepatitis B virus infection.

HBV-Specific Adaptive Immunity

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

Transfusion of autologous cytokine-induced killer cells inhibits viral replication in patients with chronic hepatitis B virus infection

Adoptive immune transfer plays an important role in clearance of hepatitis B virus (HBV) in chronic hepatitis B (CHB) patients. However, it is unclear whether cytokine-induced killer (CIK) cells could suppress HBV replication in CHB patients, especially if drug resistance develops. In this study, functional CIK cells were efficiently generated from 21 CHB patients and were transfused in an autologous manner. We found that CIK cells from the CHB patients displayed substantial proliferation and function. Administration of the CIK cells closely correlated with the decrease in the serum HBV load and improvement in liver function in some patients. The virological response rate in patients with baseline serum alanine aminotransferase (ALT) levels of >40 U/L was higher than that in patients with baseline serum ALT levels of < or = 40 U/L. Moreover, patients who had HBeAg loss or showed seroconversion generally had baseline serum ALT levels of >40 U/L. No serious side effects were observed. This protocol represents an alternative immune therapeutic strategy for the disease.

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.

Cellular and humoral immune response to a third generation hepatitis B vaccine

Liver transplantation is often the ultimate option of therapy for chronically hepatitis B virus (HBV) infected patients. Adoptive transfer of HBV immunity with the liver after vaccination of living liver donors (LLD) could be a new approach to prevent reinfection in the recipients. The time to achieve HBV immunity in LLD is usually short (1-2 months). Therefore, we established a short time immunization protocol (four injections in 2 weeks intervals) using Hepimmune, a recombinant vaccine that contains the L, M and S proteins of HBV. We examined cellular and humoral immune responses after immunization with Hepimmune and compared its immunogenicity to that of a standard HBV vaccine containing only the S protein (HBVAXPRO). Cellular immunity was measured by interferon (IFN)-gamma ELISpot and proliferation assay. HBV-specific T cells were detectable in the Hepimmune group after the second and in the standard group after the third vaccination. IFN-gamma production of T cells was significantly higher (P < 0.001) after the third vaccination with Hepimmune. Proliferative responses were also significantly (P < 0.01) higher in the Hepimmune group after the second to fourth vaccination. The humoral immune response could already be detected after the first immunization in nine of 15 Hepimmune vaccinated test persons while it was only observed in one of 15 probands of the later group. Titres differed significantly (P < 0.01) following all four vaccinations. Thus, Hepimmune appears to be a good candidate for short time immunization protocols.

Liver transplantation for hepatitis B-related cirrhosis: recent advances

In the absence of preventative therapy, deceased-donor liver transplantation indicated for hepatitis B virus (HBV) cirrhosis results in dismal graft and patient survival due to HBV infection of the liver graft. Major advances in the management of HBV-infected recipients during the past 15 years have reduced the rate of graft infection, resulting in improved outcomes, comparable to those for patients transplanted for non-HBV indications. Long-term use of hepatitis B immunoglobulin for passive immunotherapy is effective in preventing re-infection. Combination therapy with hepatitis B immunoglobulin and lamivudine after liver transplantation reduces HBV recurrence. Adefovir dipoxil is a safe and effective alternative oral antiviral treatment for lamivudine-resistant mutant HBV. The high cost of hepatitis B immunoglobulin remains a problem that must be overcome by the development of HBV vaccines and potent adjuvants.

Screening, prevention and treatment of viral hepatitis B reactivation in patients with haematological malignancies

The prevalence of hepatitis B virus (HBV) infection in patients with haematological malignancies is increased compared with the general population worldwide. HBV reactivation is common following chemotherapy and is associated with a high mortality despite prompt anti-viral treatment. HBV reactivation may necessitate interruption of chemotherapy with adverse prognostic consequences for the haematological disease. Chemotherapy-induced immune suppression may lead to increased HBV replication. Immune reconstitution within the weeks and months following recovery from chemotherapy may be associated with a flare of hepatitis B manifested by hepatocellular injury. Risk factors associated with HBV reactivation include detectable hepatitis B surface antigen (HBsAg), HBV DNA, Hepatitis B e (HBeAg) antigen, antibodies to hepatitis B core antigen (anti-HBc), treatment with corticosteroids, young age and male gender. Lamivudine is effective during HBV reactivation due to immune suppression. Clinical trials have demonstrated that pre-emptive antiviral treatment with lamivudine is superior to deferred treatment. Current recommendations emphasise screening for HBV infection in all haematology patients, particularly prior to chemotherapy. Patients who are HBsAg positive or HBV DNA positive should receive pre-emptive treatment with lamivudine before chemotherapy. The duration of lamivudine treatment may be prolonged commensurate with the degree of immunosuppression. HBV naïve patients should be immunised against hepatitis B, as should haematopoietic stem cell donors. In summary, overt and occult HBV pose a serious, but preventable, threat. Pre-treatment screening of patients at risk should be practiced diligently by all clinicians that treat patients with malignancies.

The woodchuck as an animal model for pathogenesis and therapy of chronic hepatitis B virus infection

This review describes the woodchuck and the woodchuck hepatitis virus (WHV) as an animal model for pathogenesis and therapy of chronic hepatitis B virus (HBV) infection and disease in humans. The establishment of woodchuck breeding colonies, and use of laboratory-reared woodchucks infected with defined WHV inocula, have enhanced our understanding of the virology and immunology of HBV infection and disease pathogenesis, including major sequelae like chronic hepatitis and hepatocellular carcinoma. The role of persistent WHV infection and of viral load on the natural history of infection and disease progression has been firmly established along the way. More recently, the model has shed new light on the role of host immune responses in these natural processes, and on how the immune system of the chronic carrier can be manipulated therapeutically to reduce or delay serious disease sequelae through induction of the recovery phenotype. The woodchuck is an outbred species and is not well defined immunologically due to a limitation of available host markers. However, the recent development of several key host response assays for woodchucks provides experimental opportunities for further mechanistic studies of outcome predictors in neonatal- and adult-acquired infections. Understanding the virological and immunological mechanisms responsible for resolution of self-limited infection, and for the onset and maintenance of chronic infection, will greatly facilitate the development of successful strategies for the therapeutic eradication of established chronic HBV infection. Likewise, the results of drug efficacy and toxicity studies in the chronic carrier woodchucks are predictive for responses of patients chronically infected with HBV. Therefore, chronic WHV carrier woodchucks provide a well-characterized mammalian model for preclinical evaluation of the safety and efficacy of drug candidates, experimental therapeutic vaccines, and immunomodulators for the treatment and prevention of HBV disease sequelae.

Identification of hepatitis B virus-specific lymphocytes in human liver grafts from HBV-immune donors

Both animal and human studies have demonstrated the adoptive transfer of immunity against hepatitis B virus (HBV) through liver transplantation that may be attributed to the presence of HBV-specific immunocompetent cells of donor origin in liver grafts. In this study, we characterized the resident lymphocytes in 41 human liver grafts by immunohistochemical staining and flow cytometry and directly identified the intragraft HBV-specific lymphocytes in relation to the donor's and subsequent recipient's immunity using enzyme-linked immunospot assay. A significant number of HBV-specific T and B cells were detectable in 59.4% (19/32) and 28.1% (9/32), respectively, of liver grafts from HBV-immune donors. The presence of various HBV-specific lymphocytes was closely associated with each other and with a higher serum titer of antibody against hepatitis B surface antigen (anti-HBs) in donors (P < 0.05). After liver transplantation, 17 of 35 (48.6%) patients with chronic HBV infection showed a spontaneous anti-HBs production, which was significantly associated with a higher number of donor-derived T lymphocytes specific for hepatitis B surface antigen (P = 0.043). In conclusion, the presence of considerable numbers of donor-derived HBV-specific immunocompetent cells in grafts may account for the adoptive transfer of HBV immunity through liver transplantation.

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A long-term follow-up study on hepatitis B surface antigen-positive patients undergoing allogeneic hematopoietic stem cell transplantation

The long-term hepatic complications after allogeneic hematopoietic stem cell transplantation (HSCT) in hepatitis B virus (HBV) endemic area are unknown. We examined the serological and liver-related outcome of 803 consecutive patients who received allogeneic HSCTs, with a median follow-up period of 83 months (range, 0.5-155 months). Late HBV-related hepatitis occurred in 2 of the 721 hepatitis B surface antigen-negative (HBsAg-) recipients compared with 16 of the 82 HBsAg+ recipients after HSCT (0.3% vs 19.5%; P < .001 by log-rank). Liver cirrhosis developed in 8 of the 82 HBsAg+ recipients compared with none of the 721 HBsAg- recipients (9.8% vs 0%; P < .001 by log-rank). Twenty of the 31 (64.5%) HBsAg+ recipients of hematopoietic stem cells from donors with natural immunity to HBV had sustained serologic clearance of HBsAg after HSCT. Eight of the 62 recipients without sustained HBsAg clearance compared with none of the 20 recipients with sustained HBsAg clearance developed liver cirrhosis (12.9% vs 0%; P = .02 by log-rank). Our study showed that long-term hepatic complications occur in a significant proportion of HBsAg+ patients after HSCT and the incidence of liver cirrhosis is reduced in those with sustained serologic clearance of HBsAg after HSCT.

Advances in immunomodulating therapy of HBV infection

Patients with chronic hepatitis B virus (HBV) infection have a higher risk of developing liver cirrhosis and hepatocellular carcinoma. Interferon-alpha, lamivudine and adefovir dipivoxil are the three approved treatment for chronic HBV infection and offers the only means of preventing the development of these complications. However, the efficacy of these agents, in terms of loss of Hepatitis B e antigen with or without seroconversion to Hepatitis B e antibody, normalization of serum alanine transaminase levels, loss of serum HBV DNA, and improvement in liver histology can only be achieved in 20-30% of those treated. Long-term treatment with either lamivudine or adefovir dipivoxil can result in the development of drug resistant mutants leading to an increased length of treatment with additional nucleoside analogues. These limitations of the current antiviral therapies underline the need for alternative therapies. Specific and nonspecific immunotherapeutic strategies to restore effective virus-specific T cell responses in those with chronic HBV infection offers an interesting alternative approach. These immunotherapeutic therapies include the adoptive transfer of HBV immunity, pegylated interferon and therapeutic vaccine therapies.

Management of HBV Infection in Liver Transplantation Patients

In the absence of preventative therapy, reinfection of allografts with hepatitis B virus (HBV) after orthotopic liver transplantation (OLT) resulted in dismal allograft and patient survival. Major advances in the management of HBV-infected recipients of OLT during the past 15 years have steadily reduced the rate of reinfection, resulting in improved outcomes. Initially, long-term use of hepatitis B immune globulin (HBIG) as a source of anti-HBs antibodies was effective in preventing or delaying reinfection. Lamivudine monotherapy made it possible to suppress HBV replication prior to OLT, markedly decreasing the risk of reinfection. Although lamivudine monotherapy used before and after OLT could prevent reinfection, its effectiveness was limited by progressive development of lamivudine-resistant mutant infections. Combination therapy with HBIG and lamivudine after OLT reduced both HBV recurrence and the risk of lamivudine resistance even in patients with active HBV replication. Introduction of adefovir provided a safe, alternative oral antiviral able to treat effectively lamivudine-resistant mutants HBV. Available strategies to prevent reinfection have resulted in OLT outcomes for HBV-infected patients comparable to those for patients transplanted for non-HBV indications. In the future, combination therapies of HBIG and both nucleoside and/or nucleotide agents will undoubtedly be optimized. Development of new drugs to treat HBV will increase opportunities to combine agents to enhance safety, efficacy and prevent emergence of HBV escape mutants. New vaccines and adjuvants may make it possible to generate anti-HBs in immunosuppressed patients, eliminating the need for HBIG.

Induction of oral immune regulation towards liver-extracted proteins for treatment of chronic HBV and HCV hepatitis: results of a phase I clinical trial

BACKGROUND

Anti-viral immunity can be modulated via oral feeding of viral proteins. Hepatitis B and C viral (HBV, HCV)-associated hepatocellular injury is mediated by a defective host anti-viral immune response.

AIMS

To determine the effect of oral administration of a mixture of liver-extracted proteins with HBV/HCV proteins, on viral load, liver injury, and the anti-viral T-cell response of chronic HBV/HCV patients.

METHODS

Fourteen patients with chronic HBV and 15 patients with chronic HCV were treated orally with hepatocyte-extracted proteins and HBV or HCV viral proteins for 24 weeks, and followed for an additional 26 weeks. Patients were monitored for HBV-DNA or HCV-RNA levels, liver enzymes and liver histology. Viral-directed T-cell immunity was assessed by IFNgamma and IL10 ELISPOT, viral-specific T-cell proliferation, cytotoxicity, and cytokines assays, and followed for peripheral natural killer T-cell (NKT) number.

RESULTS

In both chronic HBV and HCV patients, oral administration of a mixture of selected liver-extracted proteins and viral proteins induced a favorable increase in viral-specific T-cell proliferation, and IFNgamma-secreting clones, along with a significant decrease in the anti-viral IL10-secreting T-cell clones. However, the effects of modulation of the anti-viral immunity differed between the HBV and HCV patients. In both groups, no major adverse events were noted. In chronic HBV patients, a significant decrease in viral load was observed in 5/14 (35.7%) of patients. HB surface antigen/HB nucleocapsid antigen scores on liver biopsy improved in 46.1% and 50%, respectively, and the histological necroinflammatory score improved in 4/13 (30.7%). Forty percent of the patients with elevated liver enzymes showed a favorable biochemical response. In contrast, an improvement in the histological necroinflammatory score was observed in only 2/12 (17%) of the chronic HCV patients. No significant decrease in HCV RNA was noted in any of these patients.

CONCLUSIONS

Immune regulation of the anti-HBV/HCV immune response via oral administration of a mixture of liver-extracted and viral proteins significantly altered the viral-specific immunity. This effect was associated with clinical and virological improvements in chronic HBV patients.

Adoptive transfer of immunity: a new strategy to interfere with severe hepatitis virus reinfection after woodchuck liver transplantation

BACKGROUND

The effective transfer of humoral immunity to hepatitis B virus was first demonstrated after clinical and experimental bone marrow transplantation. This strategy is now evaluated in the woodchuck transplantation model, in which protection from reinfection can be tested.

METHODS

Animals negative for woodchuck hepatitis virus (WHV) (n = 3) were vaccinated using plasmids expressing woodchuck hepatitis virus surface (WHs), woodchuck hepatitis virus core (WHc), and woodchuck interferon-gamma in combination with a protein vaccine (WHs antigen [Ag]) three times before liver donation. Control animals (n= 4) received the liver from non-immunized donors. Chronic WHV carriers served as recipients. The viral load in serum and liver tissue was monitored pretransplant and posttransplant for up to 11 weeks by dot blot, Northern blot, Southern blot, and immunohistochemistry for WHc and WhsAg.

RESULTS

Donor vaccination was effective, as indicated by the development of anti-WHc and anti-WHs antibodies. Transplanting the livers of these donors resulted in a reduction of viral load in two of three animals. No viral DNA was detected in repeated serum samples by dot-blot hybridization technique. However, polymerase chain reaction for viral DNA extracted from serum was always positive. WHV replication intermediates and WHV RNA were absent in repeated liver biopsies. Only few hepatocytes stained weakly positive for WHc protein and frequency, and the intensity of WHsAg positive hepatocytes was low. The third animal developed severe reinfection within 3 weeks, similar to the woodchucks in the control group.

CONCLUSIONS

Liver transplantation from immunized donors to chronic carriers seems to be a promising strategy to reduce and delay severe reinfection, which may be applicable in clinical liver transplantation.

Treatment of chronic hepatitis B virus infection via oral immune regulation toward hepatitis B virus proteins

OBJECTIVES

Hepatitis B virus (HBV) is a noncytopathic virus, and hepatocellular injury is mediated by a defective host antiviral immune response. We have previously shown that antiviral immunity can be modulated through oral feeding of viral proteins. The aims of this study were to determine the safety and efficacy of treatment of patients with chronic HBV by means of p.o. administration of HBV envelope proteins.

METHODS

A total of 42 chronic HBV patients were treated p.o. with HBV envelope proteins (HBsAg+preS1+preS2), three times/wk for 20-30 wk, and followed for an additional 20 wk. Patients were monitored for HBV-DNA levels, liver enzymes, and liver histology. HBV-directed T cell immune modulation was assessed in vitro by HBV specific T cell-proliferation, cytotoxicity, IFN gamma, and IL10 ELISPOT assays, and reverse transcription-polymerase chain reaction cytokines assay.

RESULTS

Favorable response in one of the primary endpoints was achieved in 28/42 patients (66.6%) by means of p.o. immune regulation. A significant decrease in viral load was observed in 15 patients (35.7%). HBsAg/HBcAg biopsy scores improved in 41% and 57.1% of patients, respectively. Histological improvement in liver necroinflammatory score was noted in 12/40 patients (30%). In all, 80% showed biochemical response. Five of 19 HBeAg positive patients (26.3%) became negative for HBeAg. A favorable augmentation in anti-HBV specific T cell response, with increased HbsAg specific T cell proliferation (78%), cytotoxicity (75%), and IFN gamma positive T cell clones (62.9%) was noted. In addition, a decrease in the IL10 gamma positive T cell clones was achieved (48.1%). Natural killer T (NKT) lymphocytes increased significantly in all treated patients.

CONCLUSIONS

Immune regulation of the anti-HBV immune response via p.o. administration of HBV envelope proteins alleviated the immune-mediated liver injury while augmenting the effective antiviral immunity.