Tfh cell-mediated humoral immune response and HBsAg level can predict HBeAg seroconversion in chronic hepatitis B patients receiving peginterferon-α therapy

The role of regulatory T cells and follicular T helper cells in HBV infection

Hepatitis B has become one of the major global health threats, especially in developing countries and regions. Hepatitis B virus infection greatly increases the risk for liver diseases such as cirrhosis and cancer. However, treatment for hepatitis B is limited when considering the huge base of infected people. The immune response against hepatitis B is mediated mainly by CD8+ T cells, which are key to fighting invading viruses, while regulatory T cells prevent overreaction of the immune response process. Additionally, follicular T helper cells play a key role in B-cell activation, proliferation, differentiation, and formation of germinal centers. The pathogenic process of hepatitis B virus is generally the result of a disorder or dysfunction of the immune system. Therefore, we present in this review the critical functions and related biological processes of regulatory T cells and follicular T helper cells during HBV infection.

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.

A Nomogram for Predicting Non-Rebound in HBV-Infected Pregnant Women With Mother-to-Child Transmission Prevention

Background: Current guidelines recommend that pregnancies with mother-to-child transmission (MTCT) prevention can cease antiviral treatment after delivery. We aimed to develop a nomogram for predicting non-rebound in HBV-infected pregnant women with MTCT prevention after post-partum nucleos(t)ide analogs (NAs) withdrawal based on parameters before treatment cessation.

Methods: Pregnant women receiving antiviral therapy for MTCT prevention and who withdrew from taking NAs after delivery were included in this study. We used the least absolute shrinkage and selection operator (LASSO) logistics and a two-way stepwise regression to select prognostic factors for the risk model, and the concordance index (C-index) was used to assess its discrimination. Internal validation was performed through bootstrapping.

Results: Of 92 included patients, 16 and 76 experienced non-rebound and virologic rebound within 48 weeks of post-partum NAs cessation, respectively. Platelet to lymphocyte ratio (PLR) at 34 ± 2 weeks of gestation, a reduction in hepatitis B surface antigen (HBsAg) from baseline to 34 ± 2 weeks of gestation, and hepatitis B virus (HBV) DNA declining from baseline to the end of treatment (EOT) were entered into the final risk model. Its C-index was 0.91 (95% CI, 0.82–0.99), and it reached as high as 0.88 after bootstrapping validation. The decision curve and decision tree were further developed to facilitate the application of this model.

Conclusions: We developed a nomogram for predicting non-rebound in pregnant women with MTCT prevention after the withdrawal of antiviral agents, which facilitates physicians in making appropriate treatment recommendations.

B Cell-mediated Humoral Immunity in Chronic Hepatitis B Infection

B cell-mediated humoral immunity plays a vital role in viral infections, including chronic hepatitis B virus (HBV) infection, which remains a critical global public health issue. Despite hepatitis B surface antigen-specific antibodies are essential to eliminate viral infections, the reduced immune functional capacity of B cells was identified, which was also correlated with chronic hepatitis B (CHB) progression. In addition to B cells, T follicular helper (Tfh) cells, which assist B cells to produce antibodies, might also be involved in the process of anti-HBV-specific antibody production. Here, we provide a comprehensive review of the role of various subsets of B cells and Tfh cells during CHB progression and discuss current novel treatment strategies aimed at restoring humoral immunity. Understanding the mechanism of dysregulated B cells and Tfh cells will facilitate the ultimate functional cure of CHB patients.

The Multiple Functions of B Cells in Chronic HBV Infection

Chronic hepatitis B virus (HBV) infection is one of the main causes of liver diseases, of which the natural history and clinical outcomes are associated with the role of B cells. As humoral immune cells, B cells play a critical role in the process of anti-HBV antibody production. In addition, some studies have also characterized other B cell subsets involved in antigen presentation and regulating the immune response beyond antibody secretion. However, not all B cell subsets play a positive role in the immune response to chronic HBV infection, and various B cell subsets jointly mediate persistent HBV infection, tolerance, and liver damage. Thus, we further sought to elucidate the multiple functions of B cells to gain novel insight into the understanding of chronic hepatitis B (CHB) pathogenesis. We also reviewed the current immunotherapies targeting B cells to explore novel therapeutic interventions for the treatment of chronic HBV infection.

Designing a therapeutic hepatitis B vaccine to circumvent immune tolerance

An effective prophylactic hepatitis B virus (HBV) vaccine has long been available but is ineffective for chronic infection. The primary cause of chronic hepatitis B (CHB) and greatest impediment for a therapeutic vaccine is the direct and indirect effects of immune tolerance to HBV antigens. The resulting defective CD4⁺/CD8⁺ T cell response, poor cytokine production, insufficient neutralizing antibody (nAb) and poor response to HBsAg vaccination characterize CHB infection. The objective of this study was to develop virus-like-particles (VLPs) that elicit nAb to prevent viral spread and prime CD4⁺/CD8⁺ T cells to eradicate intracellular HBV. Eight neutralizing B cell epitopes from the envelope PreS1 region were consolidated onto a species-variant of the HBV core protein, the woodchuck hepatitis core antigen (WHcAg). PreS1-specific B cell epitopes were chosen because of preferential expression on HBV virions. Because WHcAg and HBcAg are not crossreactive at the B cell level and only partially cross-reactive at the CD4⁺/CD8⁺ T cell level, CD4⁺ T cells specific for WHcAg-unique T cell sites can provide cognate T-B cell help for anti-PreS1 Ab production that is not curtailed by immune tolerance. Immunization of immune tolerant HBV transgenic (Tg) mice with PreS1-WHc VLPs elicited levels of high titer anti-PreS1 nAbs equivalent to wildtype mice. Passive transfer of PreS1 nAbs into human-liver chimeric mice prevented acute infection and cleared serum HBV from mice previously infected with HBV in a model of CHB. At the T cell level, PreS1-WHc VLPs and hybrid WHcAg/HBcAg DNA immunogens elicited HBcAg-specific CD4⁺ Th and CD8⁺ CTL responses.

Use of ELISpot assay to study HBs-specific B cell responses in vaccinated and HBV infected humans

Hepatitis B surface antibody (HBsAb) plays a critical role in protecting against infection of hepatitis B virus (HBV) and were extensively studied in literature. At the same time, the status of hepatitis B surface antigen (HBs)-specific B cells in both vaccinated and HBV infected people received limited attention. In the current study, we adopted a highly specific B-cell Enzyme Linked ImmunoSpot (ELISpot) assay to analyze HBs-specific B cells in various clinical settings: healthy individuals with the history of HBV vaccination before and after receiving an extra HBV vaccine boost, people chronically infected with HBV (CHB) in various clinical stages, with or without a particular type anti-viral treatment, or whether receiving a dose of HBV vaccine. In all of these cases, B-cell ELISpot assay was used effectively in enumerating the frequency of HBs-specific B cells. While the focus of the current report was to establish the utility of this assay for HBV research, a number of interesting observations were made in this pilot study based on the profiles and dynamics of HBs-specific B cells in various conditions. Such information is useful to guide the future work in designing novel therapeutic strategies against CHB.

Immune correlates of hepatitis B surface antigen spontaneous seroconversion in hepatitis B e antigen negative chronic hepatitis B patients

BACKGROUND

Hepatitis B surface antigen (HBsAg) seroconversion in HBeAg -ve chronic hepatitis B (CHB) infection is rare, possibly due to poor antigen processing and impaired humoral response. We investigated the role of dendritic cells (DCs), T follicular helper (TFH) cells and plasma B cells in seroconversion.

METHODS

HBeAg -ve (n=135) CHB patients with raised ALT at baseline were followed up. Patients undergoing HBsAg seroconversion (Gr. I, n=11) were compared with non-converters with low (Gr. II, n=17, HBV DNA<2000 IU/mL) or high HBV DNA (Gr. III, HBV DNA >2000 IU/mL, n=17). We measured cell phenotypes (TFH, B and DCs), HBV specific T-cell functionality [using pooled overlapping surface and core peptides], IL21 levels and gene expression analysis by qRT-PCR.

RESULTS

Patients in Gr. I compared to Gr. II and III, had higher IL-21 levels (865 vs 276 vs 111 pg/mL, P=<.0001), TFH (CD4⁺ CXCR5⁺ ) cells (12.3 vs 4.67 vs 2.77, P=<.001), inducible T-cell co-stimulator (ICOS) expression on TFH cells (20.0 vs 13.0 vs 13.68, P=.01), HBsAg specific IL-17 (9.40 vs 2.33 vs 2.61, P=<.001) and TNF-α secreting TFH17 cells (82 vs 1.43 vs 2.33, P=<.001), plasma B (CD19⁺ CD38⁺ ) cells (15.0 vs 5.08 vs 5.57, P=<.001), myeloid (17.80 vs 5.39 vs 2.70, P=<.001) and plasmocytoid DCs (2.6 vs 0.43 vs 0.21, P=<.001). Plasma B-cell frequency (R² =.64, P=.01) and IL-21 levels (R² =.52, P=.003) correlated with anti-HBs titres in patients with HBsAg seroconversion.

CONCLUSIONS

Dendritic cell and TFH cell mediated responses regulate humoral responses against HBV and play a major role in HBsAg seroconversion in CHB patients.