Restoration of T cell function in chronic hepatitis B patients upon treatment with interferon based combination therapy

Predicting relapse after achieving a functional cure for chronic hepatitis B (CHB) using baseline HBsAg and end-of-treatment HBsAb levels

Among the factors influencing relapse after clinical cure of chronic hepatitis B(CHB). There is no standardization of baseline HBsAg levels and end-of-treatment HBsAb levels. This multicenter, retrospective study enrolled 136 patients who achieved functional cure from June 2019 to December 2023, and a total of 48 weeks of follow-up was conducted after treatment cessation according to the CHB guidelines. Baseline characteristics of patients were analyzed using univariates. Multifactorial logistic regression was used to analyze the different levels of HBsAg at baseline and HBsAb at the end of treatment in CHB recurrence. The working characteristic curve of the subject was constructed and observed by the column line graphical prediction model. Our data showed the cumulative recurrence rate using Kaplan-Meier survival analysis. At baseline, the level of HBsAg was significantly greater in the group with recurrence than in the group without recurrence (P = 0.038). At EOT, HBsAb levels were lower in the relapsed group than in the nonrelapsed group (P = 0.014). Multivariate logistic regression analysis revealed that a baseline serum HBsAg concentration ≥ 100 IU/mL was a risk factor for recurrence, and an EOT serum HBsAb concentration ≥ 500 mIU/mL was a protective factor for recurrence. Kaplan-Meier survival analysis showed relapse rates of 3.8% and 12.2% for HBsAg ≤ 100 IU/mL at baseline and HBsAb ≥ 500 mIU/mL at the end of treatment, respectively. Functionally cured patients with CHB when baseline HBsAg ≤ 100 IU/mL and HBsAb ≥ 500 mIU/mL at the end of treatment have a low relapse rate.

Assessing the chronic hepatitis B adaptive immune response by profiling specific T-cell receptor repertoire

Challenges in assessing hepatitis B virus (HBV)-specific T cell immunity as an immunological biomarker still remain in chronic hepatitis B (CHB), such as the requirement of large quantities of cells. This study aims to conveniently assess HBV-specific T cells immunity in chronic HBV infected patients. We obtained T cell receptor β chains (TCRβs) from public databases and six acute hepatitis B patients to establish an HBV-specific TCRβs dataset. For some TCRs from one AHB patient, their specificities and epitopes were verified. The potential HBV-specific TCRβs from CHB patients were analyzed using GLIPH2 and established dataset. By analyzing two antiviral therapy cohorts including 42 CHB patients, we showed that individuals with better therapy response may depend more on newly emerging potential HBV-specific TCRβs. In a cross-sectional study containing 207 chronic HBV infected patients, the results exhibited that the characteristics of potential HBV-specific clusters were divergent between CHB and hepatocellular carcinoma patients. Our strategy could profile potential HBV-specific TCRβ repertoire using a small blood sample, which will complement traditional methods for assessing the HBV-specific T cell immunity.

Hepatitis B functional cure and immune response

Hepatitis B virus (HBV) is a hepatotropic virus, which damage to hepatocytes is not direct, but through the immune system. HBV specific CD4+ T cells can induce HBV specific B cells and CD8+ T cells. HBV specific B cells produce antibodies to control HBV infection, while HBV specific CD8+ T cells destroy infected hepatocytes. One of the reasons for the chronicity of HBV infection is that it cannot effectively activate adoptive immunity and the function of virus specific immune cells is exhausted. Among them, virus antigens (including HBV surface antigen, e antigen, core antigen, etc.) can inhibit the function of immune cells and induce immune tolerance. Long term nucleos(t)ide analogues (NAs) treatment and inactive HBsAg carriers with low HBsAg level may "wake up" immune cells with abnormal function due to the decrease of viral antigen level in blood and liver, and the specific immune function of HBV will recover to a certain extent, thus becoming the "dominant population" for functional cure. In turn, the functional cure will further promote the recovery of HBV specific immune function, which is also the theoretical basis for complete cure of hepatitis B. In the future, the complete cure of chronic HBV infection must be the combination of three drugs: inhibiting virus replication, reducing surface antigen levels and specific immune regulation, among which specific immunotherapy is indispensable. Here we review the relationship, mechanism and clinical significance between the cure of hepatitis B and immune system.

Interferon add-on therapy increased clinical cure significantly for interferon-experienced chronic hepatitis B patients with low HBsAg

Currently, interferon add-on therapy brings hope for clinical cure of chronic hepatitis B patients with low HBsAg. However, in clinical practice patients with poor responses to their first interferon therapy were often switched to nucleos(t)ide analog therapy and then labeled as unsuitable patients for interferon therapy. Even if their HBsAg levels dropped to a low level, they were reluctant or not recommended to take interferon again, which caused them to miss out on interferon add-on therapy and clinical cure. Therefore, it is urgent to elucidate the effectiveness of interferon add-on therapy to get clinical cure for these interferon-experienced patients with low HBsAg. The purpose of this study was to investigate whether interferon-experienced patients could achieve the same HBsAg clearance and HBsAg seroconversion rates as interferon-naive patients. Also, the associated factor of HBsAg clearance and seroconversion were aimed to be clarified. 292 patients, including 85 interferon-experienced patients, were enrolled with HBsAg< 1500 IU/ml, HBeAg negative and HBV-DNA negative. And then, peg-interferon α-2b add-on therapy was performed. The results showed that the week 48 HBsAg clearance and seroconversion rates of all patients were 29.8% and 22.0%. There was no statistically significant difference between interferon-experienced and interferon-naive patients in week 48 HBsAg clearance and seroconversion rates, suggesting satisfactory clinical cure of the interferon add-on therapy for interferon-experienced patients. The age, baseline HBsAg, and week 12 HBsAg were negative correlated factors for week 48 HBsAg clearance and seroconversion. Furthermore, the age, baseline HBsAg and week 12 HBsAg for predicting the week 48 HBsAg clearance were cut off at 40.5 years, at 152.0 IU/ml and at 34.99 IU/ml, and for predicting seroconversion were cut off at 40.5 years, at 181.9 IU/ml and at 34.99 IU/ml, correspondingly. Significantly, interferon-experienced patients with low HBsAg were suggested with interferon add-on therapy to achieve clinical cure as soon as possible. This research provided evidences and cut-offs for the interferon add-on therapy against chronic hepatitis B.

Immune Mechanisms Underlying Hepatitis B Surface Antigen Seroclearance in Chronic Hepatitis B Patients With Viral Coinfection

It is considered that chronic hepatitis B patients have obtained functional cure if they get hepatitis B surface antigen (HBsAg) seroclearance after treatment. Serum HBsAg is produced by cccDNA that is extremely difficult to clear and dslDNA that is integrated with host chromosome. High HBsAg serum level leads to failure of host immune system, which makes it unable to produce effective antiviral response required for HBsAg seroclerance. Therefore, it is very difficult to achieve functional cure, and fewer than 1% of chronic hepatitis B patients are cured with antiviral treatment annually. Some chronic hepatitis B patients are coinfected with other chronic viral infections, such as HIV, HCV and HDV, which makes more difficult to cure. However, it is found that the probability of obtaining HBsAg seroclearance in patients with coinfection is higher than that in patients with HBV monoinfection, especially in patients with HBV/HIV coinfection who have an up to 36% of HBsAg 5-year-seroclerance rate. The mechanism of this interesting phenomenon is related to the functional reconstruction of immune system after antiretroviral therapy (ART). The quantity increase and function recovery of HBV specific T cells and B cells, and the higher level of cytokines and chemokines such as IP-10, GM-CSF, promote HBsAg seroclearance. This review summarizes recent studies on the immune factors that have influence on HBsAg seroconversion in the chronic hepatitis B patients with viral coinfection, which might provide new insights for the development of therapeutic approaches to partially restore the specific immune response to HBV and other viruses.

T follicular helper cells improve the response of patients with chronic hepatitis B to interferon by promoting HBsAb production

BACKGROUND AND AIMS

Hepatitis B surface antigen (HBsAg) seroconversion is considered the optimal outcome of the treatment of chronic hepatitis B virus (HBV) infection. In this study, we aimed to determine the cellular and molecular mechanisms by which pegylated interferon alpha (PEG-IFN-α) improves the seroconversion rate in patients with chronic hepatitis B (CHB).

METHODS

Flow cytometry was performed using circulating T follicular helper (TFH) cells from 15 healthy individuals and 45 patients with CHB presenting different treatment responses [complete response group (CRG), incomplete response group (ICRG), and nonresponse group (NRG)] to the standard 48-week regimen of PEG-IFN-α monotherapy to examine the significance of circulating TFH cells in the therapeutic response of patients with CHB to PEG-IFN-α. In addition, the capacities of different TFH subsets to activate B cells and stimulate IgG production were assessed by performing coculture experiments.

RESULTS

Longitudinal analysis revealed specific and significant increases in the numbers of CD40L⁺CD4⁺CXCR5⁺ TFH cells in the CRG compared with the NRG and ICRG. According to the results of in vitro coculture experiments, blocking CD40-CD40L signaling, but not ICOS-ICOSL signaling, specifically inhibits B-cell activation and IgG production. HBV may impair TFH cell function by enhancing inhibitory regulatory T-cell activity. Transcriptome analysis further revealed the upregulation of CD40L, but not of ICOS, in TFH cells isolated from the CRG.

CONCLUSIONS

TFH cells, particularly those with CD40L expression, stimulate B-cell differentiation and improve the HBsAg seroconversion rate in patients with CHB treated with PEG-IFN-α monotherapy.

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.

Distinct T-cell receptor profiles associated with hepatitis B e antigen seroconversion during entecavir treatment

BACKGROUND & AIMS

T-cell receptor (TCR) repertoire is ambiguously changed in chronic hepatitis B (CHB) patients during antivirus therapy. We tried to assess TCR repertoire dynamics and its clinical significance upon HBeAg seroconversion in CHB patients.

METHODS

Twenty CHB patients undergoing 1-year entecavir (ETV) treatment were enrolled, including 10 complete response (CR) vs 10 non-complete response (NCR) patients based on HBeAg seroconversion at week 48. The TCRβ complementarity-determining region 3 (CDR3) of peripheral CD4⁺ and CD8⁺ T cells at weeks 0, 12 and 48 was analyzed by unbiased high-throughput sequencing. The TCR repertoire profiles and their correlations with serological parameters were analyzed.

RESULTS

The diversity of TCRβ repertoires was decreasing in CR patients but increasing in NCR patients. The distribution pattern of TCR repertoires stratified according to clonotype frequencies changed in the opposite direction between CR and NCR patients. Narrow amounts of newly appearing clonotypes in CR patients experienced a more intensive and robust expansion and this phenomenon could occur as early as week 12 for the CD4⁺ subset but later at week 48 for the CD8⁺ subset. There existed some CR-exclusive clonotypes with a relatively low but increasing frequency at week 48. The number of unique TCRβ clonotypes was positively correlated with the ALT or HBV DNA level in CR patients but showed no or negative correlation in NCR patients.

CONCLUSION

Distinct TCR profiles contribute to predicting HBeAg seroconversion in CHB patients during ETV treatment and certain TCRβ CDR3 motif may be utilized for CHB immunotherapy in the future.

Effects of intrauterine exposure to maternal-derived HBeAg on T cell immunity in cord blood

Immature immune system and immune tolerance induced by exposure to HBeAg in utero and/or shortly after infection in newborns were reportedly the causes of chronic HBV infection. To investigate the effect of maternal-derived HBeAg on neonatal T cell immunity, we analysed and compared T cell phenotypes and functions among neonates born to HBsAg⁺ /HBeAg⁺ mothers (HBeAg⁺ neonates), HBsAg⁺ /HBeAg^- mothers (HBeAg^- neonates) and healthy control mothers (HC neonates), using flow cytometry. The results showed that neonatal T cell phenotypes were similar regardless of HBeAg exposure. Upon anti-CD3 and anti-CD28 stimulation in HBeAg⁺ neonates, CD4⁺ T cell production of IFN-γ (P < .05) was significantly enhanced, while CD8⁺ T cells secreted significantly more IL-2 compared with those in HBeAg^- and HC groups (P < .05). Moreover, similar levels of IFN-γ and IL-10 were observed in the culture supernatant after stimulation with rHBsAg, rHBcAg or rHBeAg among HBeAg⁺ , HBeAg^- and HC neonates, whereas HBeAg⁺ neonates produced more TNF-α than HBeAg^- neonates upon stimulation with rHBcAg. In conclusion, the results indicated that the HBsAg⁺ /HBeAg⁺ maternal environment did not influence the phenotypes of cord blood T cells but boosted neonatal non-specific Th1-type cytokine production.

Checkpoint Inhibitors and Therapeutic Vaccines for the Treatment of Chronic HBV Infection

Treatment of chronic hepatitis B virus (HBV) infection is highly effective in suppressing viral replication, but complete cure is rarely achieved. In recent years, substantial progress has been made in the development of immunotherapy to treat cancer. Applying these therapies to improve the management of chronic HBV infection is now being attempted, and has become an area of active research. Immunotherapy with vaccines and checkpoint inhibitors can boost T cell functions in vitro, and therefore may be used to reinvigorate the impaired HBV-specific T cell response. However, whether these approaches will suffice and restore antiviral T cell immunity to induce long-term HBV control remains an open question. Recent efforts have begun to describe the phenotype and function of HBV-specific T cells on the single epitope level. An improved understanding of differing T cell specificities and their contribution to HBV control will be instrumental for advancement of the field. In this review, we outline correlates of successful versus inadequate T cell responses to HBV, and discuss the rationale behind therapeutic vaccines and checkpoint inhibitors for the treatment of chronic HBV infection.

TNF-α/IFN-γ profile of HBV-specific CD4 T cells is associated with liver damage and viral clearance in chronic HBV infection

BACKGROUND & AIMS

The role of hepatitis B virus (HBV)-specific CD4 T cells in patients with chronic HBV infection is not clear. Thus, we aimed to elucidate this in patients with chronic infection, and those with hepatitis B flares.

METHODS

Through intracellular IFN-γ and TNF-α staining, HBV-specific CD4 T cells were analyzed in 68 patients with chronic HBV infection and alanine aminotransferase (ALT) <2x the upper limit of normal (ULN), and 28 patients with a hepatitis B flare. HBV-specific HLA-DRB1*0803/HLA-DRB1*1202-restricted CD4 T cell epitopes were identified.

RESULTS

TNF-α producing cells were the dominant population in patients' HBV-specific CD4 T cells. In patients with ALT <2xULN, both the frequency and the dominance of HBV-specific IFN-γ producing CD4 T cells increased sequentially in patients with elevated levels of viral clearance: HBV e antigen (HBeAg) positive, HBeAg negative, and HBV surface antigen (HBsAg) negative. In patients with a hepatitis B flare, the frequency of HBV core-specific TNF-α producing CD4 T cells was positively correlated with patients' ALT and total bilirubin levels, and the frequency of those cells changed in parallel with the severity of liver damage. Patients with HBeAg/HBsAg loss after flare showed higher frequency and dominance of HBV-specific IFN-γ producing CD4 T cells, compared to patients without HBeAg/HBsAg loss. Both the frequency and the dominance of HBV S-specific IFN-γ producing CD4 T cells were positively correlated with the decrease of HBsAg during flare. A differentiation process from TNF-α producing cells to IFN-γ producing cells in HBV-specific CD4 T cells was observed during flare. Eight and 9 HBV-derived peptides/pairs were identified as HLA-DRB1*0803 restricted epitopes and HLA-DRB1*1202 restricted epitopes, respectively.

CONCLUSIONS

HBV-specific TNF-α producing CD4 T cells are associated with liver damage, while HBV-specific IFN-γ producing CD4 T cells are associated with viral clearance in patients with chronic HBV infection.

LAY SUMMARY

TNF-α producing cells are the dominant population of hepatitis B virus (HBV)-specific CD4 T cells in patients with chronic HBV infection. This population of cells might contribute to the aggravation of liver damage in patients with a hepatitis B flare. HBV-specific IFN-γ producing CD4 T cells are associated with HBV viral clearance. Differentiation from HBV-specific TNF-α producing CD4 T cells into HBV-specific IFN-γ producing CD4 T cells might favor HBV viral clearance.

Roadmap to functional cure of chronic hepatitis B: An expert consensus

Hepatitis B virus (HBV) infection continues to be a major public health issue worldwide. HBsAg loss is associated with functional remission and improved long-term outcome, and is considered to be a 'functional cure' (also referred to as clinical or immunologic cure) for chronic hepatitis B. This ideal goal of therapy can be achieved using optimized combination regimens with direct-acting antivirals [eg nucleos(t)ide analogues (NAs)] and immunomodulators [eg pegylated interferon alpha2a (Peg-IFN)] in selected patients with chronic hepatitis B. Among different combination therapies currently available, those with NA lead-in followed by Peg-IFN in virally suppressed patients has been demonstrated to be effective. This review provides an updated overview of the evidence supporting the use of combination therapies and summarizes expert consensus on the roadmap to attain functional cure for chronic hepatitis B patients.

Combination therapy based on pegylated interferon alfa improves the therapeutic response of patients with chronic hepatitis B who exhibit high levels of hepatitis B e-antigen at 24 weeks: A retrospective observational study

Pegylated interferon alpha (PEG-IFN-α) is a first-line treatment for patients with chronic hepatitis B (CHB), but its efficacy varies from individual to individual. Early discrimination between responder and non-responder patients is important for optimal clinical management. In addition, low therapeutic efficacy is still a major issue; thus, treatment timing should be optimized.We reviewed our experience with hepatitis B e-antigen (HBeAg)-positive patients treated with PEG-IFN-α, alone or in combination with nucleoside analogues (NAs), from 2009 through 2014. Collected data included both general characteristics of 113 patients and laboratory data at baseline and at treatment weeks 12, 24, 52, and 76. The endpoint was HBeAg seroconversion at week 76.A total of 113 patients with changed to or start of NAs therapy were included in this study. At the end of treatment, 44 (38.9%) patients exhibited HBeAg seroconversion. Patients with HBeAg seroconversion had lower baseline HBeAg (475.5 vs 751.7; P = .007). The incidence of HBeAg seroconversion was significantly higher among patients with HBeAg ≤ 500 signal-to-cutoff ratio (S/CO) (OR = 2.60, 95% CI: 1.16-5.83, P = .02) at baseline, HBeAg S/CO ≤ 20 (OR = 3.37, 95% CI: 1.47-7.73, P = .003), or a higher than 10-fold HBeAg drop (OR = 3.55, 95% CI: 1.50-8.37, P = .003) at week 12 or HBeAg ≤ 15 S/CO (OR = 10.35, 95% CI: 4.09-26.20, P < .001) at week 24. Subgroup analyses demonstrated that in patients with HBeAg >20 S/CO at 24 weeks, the addition of NAs treatment may increase HBeAg seroconversion (23.3% vs 0%, P = .03).HBeAg levels had an impact on the rate of serological conversion in CHB patients receiving PEG-IFN-based treatment. Combination therapy with NAs should be considered in CHB patients maintaining a high HBeAg level after 24 weeks of PEG-IFN monotherapy.

Sequential combination therapy with interferon, interleukin-2 and therapeutic vaccine in entecavir-suppressed chronic hepatitis B patients: the Endeavor study

BACKGROUND

Switching from nucleos(t)ide analogues to interferon (IFN) improves hepatitis B surface antigen (HBsAg) loss. We aimed to evaluate whether combining immunomodulators such as interleukin-2 (IL-2) and therapeutic vaccine with IFN enhances HBsAg loss in entecavir (ETV)-suppressed patients.

METHODS

Ninety-four patients exhibiting virological suppression and hepatitis B e antigen (HBeAg) loss following ETV treatment were randomized 1:1:1 to receive ETV (group I) or IFN (group II) for 48 weeks, or IFN and vaccine for 48 weeks plus IL-2 for 12 weeks (group III). The primary endpoint was HBsAg loss at week 48. Peripheral natural killer (NK) cells and regulatory T cells (Treg) were measured as immune checkpoint indicators.

RESULTS

Mean HBsAg decline at week 48 was significantly greater in group III (0.85 log 10 IU/mL) and group II (0.74 log 10 IU/mL), than in group I (0.13 log 10 IU/mL). At week 48, 9.38%, 3.03%, and 3.70% of subjects in group III, II, and I, respectively, achieved HBsAg loss. Among patients with baseline HBsAg titers ranging from 100 to 1500 IU/mL, HBsAg loss rate was 27.3, 7.1, and 0% in group III, II, and I, respectively. Responders in group III showed a significantly higher increase in CD56^bright CD16^-NK cells from week 24 to 36, and a significant decline in Treg from week 12 to 24 than non-responders.

CONCLUSION

For ETV-suppressed patients, particularly those with low baseline HBsAg levels, combination therapy with IFN and other immunomodulators may enhance HBsAg loss, while successful response correlates with partial restoration of NK cells and Tregs.

Design, Synthesis, and Bioactive Screen In Vitro of Cyclohexyl (E)-4-(Hydroxyimino)-4-Phenylbutanoates and Their Ethers for Anti-Hepatitis B Virus Agents

A series of oxime Cyclohexyl (E)-4-(hydroxyimino)-4-phenylbutanoates and their ethers were designed, synthesized, and evaluated for anti-hepatitis B virus (HBV) activities with HepG 2.2.15 cell line in vitro. Most of these compounds possessed anti-HBV activities, and among them, compound 4B-2 showed significant inhibiting effects on the secretion of HBsAg (IC₅₀ = 63.85 ± 6.26 μM, SI = 13.41) and HBeAg (IC₅₀ = 49.39 ± 4.17 μM, SI = 17.34) comparing to lamivudine (3TC) in HBsAg (IC₅₀ = 234.2 ± 17.17 μM, SI = 2.2) and HBeAg (IC₅₀ = 249.9 ± 21.51 μM, SI = 2.07). Docking study of these compounds binding to a protein residue (PDB ID: 3OX8) from HLA-A2 that with the immunodominant HBcAg18–27 epitope (HLA-A2.1- restricted CTL epitope) active site was carried out by using molecular operation environment (MOE) software. Docking results showed that behaviors of these compounds binding to the active site in HLA-A protein residue partly coincided with their behaviors in vitro anti-HBV active screening.

Low hepatitis B surface antigen and HBV DNA levels predict response to the addition of pegylated interferon to entecavir in hepatitis B e antigen positive chronic hepatitis B

BACKGROUND

Various treatment combinations of peginterferon (PEG-IFN) and nucleos(t)ide analogues have been evaluated for chronic hepatitis B (CHB), but the optimal regimen remains unclear.

AIMS

To study whether PEG-IFN add-on increases response compared to entecavir (ETV) monotherapy, and whether the duration of ETV pretreatment influences response.

METHODS

Response was evaluated in HBeAg positive patients previously treated in two randomized controlled trials. Patients received ETV pretreatment for at least 24 weeks and were then allocated to 24-48 weeks of ETV+PEG-IFN add-on, or continued ETV monotherapy. Response was defined as HBeAg loss combined with HBV DNA <200 IU/mL 48 weeks after discontinuing PEG-IFN.

RESULTS

Of 234 patients, 118 were assigned PEG-IFN add-on and 116 continued ETV monotherapy. Response was observed in 38/118 (33%) patients treated with add-on therapy and in 23/116 (20%) with monotherapy (P = 0.03). The highest response to add-on therapy compared to monotherapy was observed in PEG-IFN naive patients with HBsAg levels below 4000 IU/mL and HBV DNA levels below 50 IU/mL at randomization (70% vs 34%; P = 0.01). Above the cut-off levels, response was low and not significantly different between treatment groups. Duration of ETV pretreatment was associated with HBsAg and HBV DNA levels (both P < 0.005), but not with response (P = 0.82).

CONCLUSIONS

PEG-IFN add-on to ETV therapy was associated with higher response compared to ETV monotherapy in patients with HBeAg positive CHB. Response doubled in PEG-IFN naive patients with HBsAg below 4000 IU/mL and HBV DNA below 50 IU/mL, and therefore identifies them as the best candidates for PEG-IFN add-on (Identifiers: NCT00877760, NCT01532843).

The impact of currently licensed therapies on viral and immune responses in chronic hepatitis B: Considerations for future novel therapeutics

Despite the availability of a preventative vaccine, chronic hepatitis B (CHB) remains a global healthcare challenge with the risk of disease progression due to cirrhosis and hepatocellular carcinoma. Although current treatment strategies, interferon and nucleos(t)ide analogues have contributed to reducing morbidity and mortality related to CHB, these therapies are limited in providing functional cure. The treatment paradigm in CHB is rapidly evolving with a number of new agents in the developmental pipeline. However, until novel agents with functional cure capability are available in the clinical setting, there is a pressing need to optimize currently licensed therapies. Here, we discuss current agents used alone and/or in combination strategies along with the impact of these therapies on viral and immune responses. Novel treatment strategies are outlined, and the potential role of current therapies in the employment of pipeline agents is discussed.

5'-triphosphate siRNA targeting HBx elicits a potent anti-HBV immune response in pAAV-HBV transfected mice

RNA with 5'-triphosphate (3p-RNA) is recognized by RNA sensor RIG-I (retinoic acid-inducible gene I protein). Previously, we reported that small interfering RNA targeting HBx (3p-siHBx) could confer potent anti-hepatitis B virus (HBV) efficacy via HBx silencing and RIG-I activation. However, the characteristics of innate and adaptive immunity especially exhaustion profiles in the liver microenvironment in response to 3p-siHBx therapy have not been fully elucidated. Here, we observed that 3p-siHBx more significantly inhibited HBV replication in vivo. 3p-siHBx enhanced natural killer (NK) cell activation with KLRG1 and CD69 upregulation and interferon (IFN)-γ secretion. 3p-siHBx significantly reversed the exhaustion phenotype of CD8⁺ T cells, and augmented CD8⁺ T cell activation and function. Importantly, 3p-siHBx disrupted the differentiation of myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg), accompanied by the reduction of the immunosuppressive cytokines interleukin (IL)-10 and transforming growth factor (TGF)-β. 3p-siHBx also enhanced dendritic cell maturation. Further investigation showed that RIG-I was involved in 3p-siHBx-induced IFN-α, IFN-β, and IFN-λ production. Moreover, RIG-I activation in HBV⁺ hepatocytes would improve the recruitment of CD8⁺ T cells and NK cells. These results reveal that 3p-siHBx therapy can improve the immune microenvironment in HBV-carrier liver and inhibit HBV replication, indicating the potential utility of RIG-I ligands as molecular adjuvants for viral vaccines or candidate drugs.

Therapeutic and immune function improvement of vitamin D combined with IFN-α on mouse with hepatitis B infection

This study aims to investigate the therapeutic effect of vitamin D (VD) combined with interferon (IFN) type I (IFN-α) on mice with hepatitis B and to explore the possible mechanism. The mice were divided into control group, model group, IFN-α group, and IFN-α ⁺ VD group. After 4 weeks, the mice of four groups were weighed, and the thymus and spleen indexes were calculated. The activity of alanine transaminase (ALT) and aspartate transaminase (AST) in the serum was detected while pathological changes of the liver were observed. The levels of interferon-γ (IFN-γ), interleukin-2 (IL-2), and interleukin-4 (IL-4) in serum were measured by enzyme-linked immunosorbent assay (ELISA). The proliferation of spleen lymphocytes was detected by MTT assay. Flow cytometry was used to detect the level of CD4⁺, CD8⁺, and CD4⁺/CD8⁺ in peripheral blood. The levels of ALT and AST in serum were significantly lower in the IFN-α ⁺ VD group than those in the IFN-α group, but the thymus and spleen indexes were significantly higher. Although both IFN-α and IFN-α ⁺ VD can improve the damaged structure of live tissue, IFN-α ⁺ VD achieved higher efficacy than IFN-α alone. The serum IFN-γ, TNF-α, and IL-2 levels were lower in the IFN-α ⁺ VD group compared with the IFN-α group, and no significant difference was found in IL-4. Compared with the IFN-α group, the percentage of CD4⁺ and the D4⁺/CD8⁺ ratio were significantly increased, but the percentage of CD8⁺ was reduced. The proliferation rate of splenic lymphocytes was higher in the IFN-α ⁺ VD group compared with the IFN-α group. IFN-α ⁺ VD was found to achieve higher efficacy than IFN-α alone for the treatment of hepatitis B in mice, possibly through increasing the immune level of mice.

Discovery of Oxime Ethers as Hepatitis B Virus (HBV) Inhibitors by Docking, Screening and In Vitro Investigation

A series of oxime ethers with C₆-C₄ fragment was designed and virtually bioactively screened by docking with a target, then provided by a Friedel–Crafts reaction, esterification (or amidation), and oximation from p-substituted phenyl derivatives (Methylbenzene, Methoxybenzene, Chlorobenzene). Anti-hepatitis B virus (HBV) activities of all synthesized compounds were evaluated with HepG2.2.15 cells in vitro. Results showed that most of compounds exhibited low cytotoxicity on HepG2.2.15 cells and significant inhibition on the secretion of HBsAg and HBeAg. Among them, compound 5c-1 showed the most potent activity on inhibiting HBsAg secretion (IC₅₀ = 39.93 μM, SI = 28.51). Results of the bioactive screening showed that stronger the compounds bound to target human leukocyte antigen A protein in docking, the more active they were in anti-HBV activities in vitro.

HBV-Derived Synthetic Long Peptide Can Boost CD4+ and CD8+ T-Cell Responses in Chronic HBV Patients Ex Vivo

Background

Vaccination with synthetic long peptides (SLP) is a promising new treatment strategy for chronic hepatitis B virus (CHB). SLP can induce broad T-cell responses for all HLA types. Here we investigated the ability of a prototype HBV-core (HBc)-sequence-derived SLP to boost HBV-specific T cells in CHB patients ex vivo.

Methods

HBc-SLP was used to assess cross-presentation by monocyte-derived dendritic cells (moDC) and BDCA1+ blood myeloid DC (mDC) to engineered HBV-specific CD8+ T cells. Autologous SLP-loaded and toll-like receptor (TLR)-stimulated DC were used to activate patient HBc-specific CD8+ and CD4+ T cells.

Results

HBV-SLP was cross-presented by moDC, which was further enhanced by adjuvants. Patient-derived SLP-loaded moDC significantly increased autologous HBcAg18-27-specific CD8+ T cells and CD4+ T cells ex vivo. HBV-specific T cells were functional as they synthesized tumor necrosis factor-alpha and interferon-gamma. In 6/7 of patients blockade of PD-L1 further increased SLP effects. Also, importantly, patient-derived BDCA1+ mDC cross-presented and activated autologous T-cell responses ex vivo.

Conclusions

As a proof of concept, we showed a prototype HBc-SLP can boost T-cell responses in patients ex vivo. These results pave the way for the development of a therapeutic SLP-based vaccine to induce effective HBV-specific adaptive immune responses in CHB patients.

Toward a Cure for Hepatitis B Virus Infection: Combination Therapy Involving Viral Suppression and Immune Modulation and Long-term Outcome

Chronic hepatitis B virus (HBV) infection remains a major global health burden. Currently, the approved therapeutic regimens include nucleos(t)ide analogues (NAs) and either interferon or pegylated interferon. NA therapy is generally safe and well tolerated, but the rate of posttreatment virologic relapse is high, making NA treatment a lifetime commitment. The benefits of pegylated interferon treatment include a finite duration, more-durable response and absence of viral resistance. However, sustained response to interferon alone is achieved only in a minority of patients, and side effects are common, which limit its clinical use. Given that HBV covalently closed circular DNA and the integrated HBV genome persist stably in the nuclei of infected hepatocytes, elimination (complete cure) of HBV is rarely achieved. After completion of treatment, sustained HBV surface antigen loss, with or without seroconversion to HBV surface antibody positivity (ie, functional cure), is therefore recommended as the ideal end point for anti-HBV treatment, despite the lack of complete eradication of HBV. Theoretically, combination of antiviral agents with differential mechanisms of actions on HBV, including viral suppression combined with immune modulation (as occurs during treatment with NA plus pegylated interferon), is an encouraging strategy to treat chronic hepatitis B. Recent studies have confirmed certain virological and serological advantages of simultaneous administration of NA and pegylated interferon (de novo combination therapy) or addition of pegylated interferon to ongoing NA therapy (sequential combination therapy) over monotherapy. Few data exist, however, on the long-term outcomes of patients receiving combination therapy. This review summarizes current combination therapy developed to cure chronic HBV infection.

Comparison of morphology, phenotypes and function between cultured human IL‑4‑DC and IFN‑DC

Dendritic cells (DCs) as professional antigen presenting cells, are important in the initiation of the primary immune response. The present study compared the morphology, phenotypes and function between monocyte‑derived human DCs produced from a conventional culturing system containing granulocyte‑macrophage colony‑stimulating factor (GM‑CSF) and IL‑4 (IL‑4‑DC) and DCs generated by the stimulation of GM‑CSF and interferon (IFN)‑α (IFN‑DC). When compared with IL‑4‑DC in morphology, IFN‑DC contained more organelles, including endoplasmic reticulum and myelin figures, whereas mature (m)IL‑4‑DC contained more vacuoles in the cells. The spikes of IFN‑DC were shorter and thicker. The expression of phenotypes between immature IFN‑DC and IL‑4‑DC were diverse. Following maturation with tumor necrosis factor‑α, IFN‑DC and IL‑4‑DC upregulated the expression of cluster of differentiation (CD) 11c and CD83. Conversely, immature IFN‑DC and IL‑4‑DC secreted few inflammatory cytokines including interleukin (IL)‑18, IL‑23, IL‑12p70, IL‑1β and anti‑inflammatory IL‑10. Following maturation, large amounts of the cytokines were secreted by these two DCs and mIFN‑DC secreted more cytokines compared with mIL‑4‑DC in general. Furthermore, immature IFN‑DC and IL‑4‑DC loaded with cytomegalovirus (CMV)‑pp65 protein were unable to induce the priming of T cells, as evaluated by the intracellular staining with IFN‑γ. Notably, mature DCs exhibited the ability to present CMV‑pp65 protein and activate T cells. The mIFN‑DC activated a greater proportion of autologous CD4+ T cells (0.91 vs. 0.31%, P<0.001) and CD8+ T cells (0.90 vs. 0.48%, P<0.001) to secret IFN‑γ compared with mIL‑4‑DC. The results suggested that the morphology, phenotypes and cytokine secretion of IFN‑DC and IL‑4‑DC were diverse. The mIFN‑DC were more effective in priming and cross‑priming T cells when compared with IL‑4‑DC.

Host-directed therapies for bacterial and viral infections

Host-directed therapy (HDT) is a novel approach in the field of anti-infectives for overcoming antimicrobial resistance.

HDT aims to interfere with host cell factors that are required by a pathogen for replication or persistence, to enhance protective immune responses against a pathogen, to reduce exacerbated inflammation and to balance immune reactivity at sites of pathology.

HDTs encompassing the 'shock and kill' strategy or the delivery of recombinant interferons are possible approaches to treat HIV infections. HDTs that suppress the cytokine storm that is induced by some acute viral infections represent a promising concept.

In tuberculosis, HDT aims to enhance the antimicrobial activities of phagocytes through phagosomal maturation, autophagy and antimicrobial peptides. HDTs also curtail inflammation through interference with soluble (such as eicosanoids or cytokines) or cellular (co-stimulatory molecules) factors and modulate granulomas to allow the access of antimicrobials or to restrict tissue damage.

Numerous parallels between the immunological abnormalities that occur in sepsis and cancer indicate that the HDTs that are effective in oncology may also hold promise in sepsis.

Advances in immune phenotyping, genetic screening and biosignatures will help to guide drug therapy to optimize the host response. Combinations of canonical pathogen-directed drugs and novel HDTs will become indispensable in treating emerging infections and diseases caused by drug-resistant pathogens.

Host-directed therapy (HDT) aims to interfere with host cell factors that are required by a pathogen for replication or persistence. In this Review, Kaufmannet al. describe recent progress in the development of HDTs for the treatment of viral and bacterial infections and the challenges in bringing these approaches to the clinic.

Despite the recent increase in the development of antivirals and antibiotics, antimicrobial resistance and the lack of broad-spectrum virus-targeting drugs are still important issues and additional alternative approaches to treat infectious diseases are urgently needed. Host-directed therapy (HDT) is an emerging approach in the field of anti-infectives. The strategy behind HDT is to interfere with host cell factors that are required by a pathogen for replication or persistence, to enhance protective immune responses against a pathogen, to reduce exacerbated inflammation and to balance immune reactivity at sites of pathology. Although HDTs encompassing interferons are well established for the treatment of chronic viral hepatitis, novel strategies aimed at the functional cure of persistent viral infections and the development of broad-spectrum antivirals against emerging viruses seem to be crucial. In chronic bacterial infections, such as tuberculosis, HDT strategies aim to enhance the antimicrobial activities of phagocytes and to curtail inflammation through interference with soluble factors (such as eicosanoids and cytokines) or cellular factors (such as co-stimulatory molecules). This Review describes current progress in the development of HDTs for viral and bacterial infections, including sepsis, and the challenges in bringing these new approaches to the clinic.

Dynamic Perturbations of CD4 and CD8 T Cell Receptor Repertoires in Chronic Hepatitis B Patients upon Oral Antiviral Therapy

Long-term treatment with nucleos(t)ide analogs (NUCs) can improve the antiviral T cell response in chronic hepatitis B (CHB) patients. Whether and to what extent the T cell response is improved by NUCs in the early stage leading to hepatitis B e antigen (HBeAg) seroconversion remain to be clarified. A total of 22 CHB patients undergoing 2-year telbivudine-based therapy were enrolled, including 10 exhibiting a complete response (CR) and 12 exhibiting a non-complete response (NCR) according to HBeAg seroconversion at week 52. Peripheral CD4⁺ and CD8⁺ T cells were sorted at baseline, weeks 12, and 24. The T cell receptor β chain (TCRβ) complementarity-determining region 3 was analyzed by unbiased high-throughput sequencing. Compared with NCR group, patients in CR group had a much lower percentage of persistent clonotypes (P < 0.001) but remarkably higher percentages of new and expanded clonotypes (P < 0.05) between any two time points for both CD4 and CD8 subsets. The CD4 T cells exhibited a stronger response than CD8 population in the patients. The number of new and expanded clonotypes was inversely associated with the decline of viral antigen. In conclusion, NUC-based therapy induces a broad and vigorous T cell response with rapid decline of antigenemia during the early stage of treatment. A broad T cell expansion is crucial for HBeAg seroconversion. Our findings suggest that the potent suppression of hepatitis B virus replication by NUC monotherapy complemented with additional immunomodulatory strategies may increase the likelihood of a functional cure for CHB in the future.

Hepatitis B virus infection and the immune response: The big questions

Clinical events and the host immune response during hepatitis B virus (HBV) infection are intricately linked. Despite decades of research, important questions concerning the immunopathogenesis of chronic HBV infection remain unanswered. For example, it is unclear which immune parameters facilitate persistence, and if HBV can be completely cleared from the human liver. Recent technological breakthroughs now allow researchers to address these seemingly basic, but essential questions surrounding HBV immunity. It will be important to better define the molecular underpinnings of immune cell function and dysfunction during chronic disease and in controlled infection, with particular focus on the liver, as little information is available on the intrahepatic compartment. In the near future, it may be possible to solve some of the controversy surrounding the immune responses to HBV, and establish the features of both the innate and adaptive arms of the immune system required to achieve sustained control of HBV infection.

Hurdles to the Development of Effective HBV Immunotherapies and HCV Vaccines

Chronic infections with HBV and HCV continue to be major public health problems, with hundreds of millions of people infected worldwide; this is despite the availability of both an effective prophylactic HBV vaccine for more than 3 decades and potent direct antivirals for HBV and, more recently, HCV infection. Consequently, development of HBV immunotherapies and prophylactic HCV vaccines remains extremely urgent, but limited funding and significant gaps in our understanding of the correlates of immune protection pose serious hurdles for the development of novel immune-based interventions. Here we discuss immunological questions related to HBV and HCV, some shared and some pertinent to only 1 of the viruses, that should be addressed for the rational design of HBV immunotherapies and HCV vaccines.

Approved Antiviral Drugs over the Past 50 Years

Since the first antiviral drug, idoxuridine, was approved in 1963, 90 antiviral drugs categorized into 13 functional groups have been formally approved for the treatment of the following 9 human infectious diseases: (i) HIV infections (protease inhibitors, integrase inhibitors, entry inhibitors, nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and acyclic nucleoside phosphonate analogues), (ii) hepatitis B virus (HBV) infections (lamivudine, interferons, nucleoside analogues, and acyclic nucleoside phosphonate analogues), (iii) hepatitis C virus (HCV) infections (ribavirin, interferons, NS3/4A protease inhibitors, NS5A inhibitors, and NS5B polymerase inhibitors), (iv) herpesvirus infections (5-substituted 2'-deoxyuridine analogues, entry inhibitors, nucleoside analogues, pyrophosphate analogues, and acyclic guanosine analogues), (v) influenza virus infections (ribavirin, matrix 2 protein inhibitors, RNA polymerase inhibitors, and neuraminidase inhibitors), (vi) human cytomegalovirus infections (acyclic guanosine analogues, acyclic nucleoside phosphonate analogues, pyrophosphate analogues, and oligonucleotides), (vii) varicella-zoster virus infections (acyclic guanosine analogues, nucleoside analogues, 5-substituted 2'-deoxyuridine analogues, and antibodies), (viii) respiratory syncytial virus infections (ribavirin and antibodies), and (ix) external anogenital warts caused by human papillomavirus infections (imiquimod, sinecatechins, and podofilox). Here, we present for the first time a comprehensive overview of antiviral drugs approved over the past 50 years, shedding light on the development of effective antiviral treatments against current and emerging infectious diseases worldwide.