High frequency of CD4+ CXCR5+ TFH cells in patients with immune-active chronic hepatitis B

Clinical characteristics and immunogenicity after Omicron breakthrough infection in patients with chronic hepatitis B infection: A longitudinal observational study

The clinical and immunological features after breakthrough infection (BTI) during Omicron wave in patients with chronic hepatitis B virus infection (CHB) are still unclear. A total of 101 patients with CHB from our previous coronavirus disease 2019 (COVID-19) vaccination cohort (NCT05007665), were continued to be followed up at the Second Affiliated Hospital of Chongqing Medical University after BTI, while an additional 39 healthcare workers after BTI were recruited as healthy controls (HCs). Clinical data were collected using questionnaire survey and electronic medical record. Blood samples were used to determine the antibody responses, as well as B and T cell responses. After BTI, the clinical symptoms of COVID-19 were mild to moderate in patients with CHB, with a median duration of 5 days. Compared with HCs, patients with CHB were more susceptible to develop moderate COVID-19. The liver function was not significantly damaged, and HBV-DNA was not activated in patients with CHB after BTI. Patients with CHB could elicit robust antibody responses after BTI (NAbs 13.0-fold, BA.5 IgG: 24.2-fold, respectively), which was also significantly higher than that in every period after vaccination (all p < 0.001), and compared to that in HCs after BTI. The CD4+, cTfh, and CD8+ T cell responses were also augmented in patients with CHB after BTI, while exhibiting comparability to those observed in HCs. In patients with CHB after BTI, the immune imprint was observed in B cell responses, rather than in T cell responses. In conclusion, Omicron breakthrough infection induced mild to moderate COVID-19 symptoms in patients with CHB, without exacerbating the progress of liver diseases. Meanwhile, BTI demonstrated the ability to induce robust antibody and T cell responses in patients with CHB, which was comparable to those observed in HCs.

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.

Changes in circulating TCF1- and GARP-associated regulatory T cell subsets reflect the clinical status of patients with chronic HBV infection

This study aimed to clarify the expression changes and clinical significance of regulatory T (Treg) cells and follicular regulatory T (TFR) cell subsets divided by glycoprotein A repetitions predominant protein (GARP) and T cell factor 1(TCF1) in peripheral blood of patients with chronic HBV infection. The peripheral blood of 26 chronic hepatitis B (CHB) patients, 27 inactive HBsAg carriers and 32 healthy controls were collected and GARP + percentages in Treg and TFR cells were analyzed by flow cytometry. In addition, Treg and TFR cell subsets sorted by CD62L and TCF1 were analyzed and compared. Correlation analyses were performed between Treg and TFR cell subpopulations and clinical parameters as well as cytokine concentrations, including IL-21, IL-10 and TGF-β1 in plasma. Circulating Treg and TFR levels were elevated in CHB patients. Moreover, GARP and TCF1 were up-regulated in circulating Treg and TFR cells of CHB patients. TCF1 + CD62L- Treg cells were increased while TCF1-CD62L + Treg cells were decreased in CHB patients. TCF1 + CD62L- and TCF1-CD62L- TFR cells were increased while TCF1 + CD62L + TFR cells were decreased in CHB patients. TCF1 + CD62L- Treg cells were positively correlated with HBV DNA, ALT and plasma IL-10, while TCF1 + CD62L + TFR cells were negatively correlated with HBV DNA, HBeAg, HBsAg, ALT, AST, T-BIL and positively correlated with plasma IL-21. Treg and TFR subsets sorted by TCF1, CD62L and GARP were changed in CHB patients. Changes in Treg and TFR functional subsets are associated with antiviral immunity in CHB patients.

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.

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.

Humoral Immune Responses and Hepatitis B Infection

BACKGROUND

Chronicity or seroclearance of hepatitis B virus (HBV) antigens is determined by the host immune responses. Current approaches to treat HBV patients are based on inhibition of replication using different antivirals (nucleoside or nucleotide analogs) as monotherapy, or along with immune modulators as combination therapy is being used worldwide for reducing the viral load. Understanding the role of immune cellular therapies with currently available treatments for persistent viral-mediated responses in HBV patients is unexplored. However, the generation of antibodies against a surface (HBs) and envelop (HBe) antigen of hepatitis B remains an issue for future studies and needs to be explored.

SUMMARY

Humoral immunity, specifically T follicular helper (TFh) cells, may serve as a target for therapy for HBsAg seroconversion. In this review, we have been engrossed in the importance and role of the humoral immune responses in CHBV infection and vertical transmission. Key Message: TFh cells have been suggested as the potential target of immunotherapy which lead to seroconversion of HBe and HBs antigens of HBV. HBsAg seroconversion and eradication of covalently closed circular DNA are the main challenges for existing and forthcoming therapies in HBV infection.

Maternal Immunity Influences Vertical Transmission of Hepatitis B to Newborns

Vertical transmission of hepatitis B virus (HBV) from the mother to the newborn often results in viral persistence. To understand mechanisms of maternofetal HBV transmission, we studied maternal immunity and peripheral blood mononuclear cell (PBMC) transcriptome in mothers and newborns. We included 50 mothers and babies who were hepatitis B surface antigen (HBsAg) positive: 22 HBV transmitting mothers (group [Gr.] I) and 28 HBV nontransmitting mothers (Gr. II) to newborns and 10 healthy mother-baby pairs (Gr. III). PBMCs were analyzed for HBV-specific dendritic cells (DCs), T cells, T follicular helper (TFh) cells, B cells, functional immune responses, and cytokine levels as well as transcriptome signatures to identify immune gene expression correlates for protective immunity. Group II mothers had lower HBsAg levels (3.82 × 10³ versus 1.493 × 10⁴; P < 0.0001) with greater HBV-specific responses of DCs, T cells, TFh cells, and B cells than Gr. I mothers. Frequencies of TFh cells were lower in Gr. I mothers, with reduced interleukin-21 (IL-21) levels, and these inversely correlated with HBV DNA levels. Cut-off levels of 9.5% and 8.93% from the receiver operating curve predicted the involvement of TFh cells and B cells in HBV transmission. Transcriptome signatures revealed that maternal gene imprints were reflected in the newborns. Genes related to DCs, TFh cells, and B cells were increased in Gr. II, and Gr. II newborns showed a boost in cellular and humoral responses after vaccination. Conclusion: In mothers infected with HBV, low serum IL-21 levels and decreased TFh-cell and plasma B-cell frequencies are associated with vertical transmission of HBV to newborns. These features are indicative of low protective maternal immunity.

Peripheral follicular helper T cells in acute viral diseases: a perspective on dengue

Follicular helper T cells (T_FH) are a predominant subset of CD4⁺ T cells specialized in providing help to B cells in germinal centers and necessary to generate T cell-dependent antibody responses. Peripheral T_FH (pT_FH) are the counterpart of T_FH found in the circulation, which resemble T_FH in many aspects of their phenotype and function. The CD4⁺ pT_FH subset has received a lot of interest recently because they are easy to access and have the potential to serve as a biomarker for long-lasting humoral immunity. This review will discuss recent findings of pT_FH in human acute viral diseases with a focus on dengue infection.

HBV induces inhibitory FcRL receptor on B cells and dysregulates B cell-T follicular helper cell axis

Spontaneous or treatment induced seroconversion in chronic HBV infection is rare and generation of anti-HBs antibodies is the current goal of HBV therapeutics. Here we investigated B and follicular T helper (Tfh) cell defects that persist in HBV infection despite long-term nucleos(t)ide analog (NUC) treatment and possible mechanisms behind them. RNA sequencing revealed that patient B cells have upregulated expression of multiple inhibitory receptors including members of FcRL family and downregulation of genes involved in antigen presentation. An expansion of atypical memory CD19⁺CD10⁻CD27⁻CD21⁻ subset of B cells, that express high levels of FcRL5, is persistently present in patients. HBs antigen specific IgG response is concentrated in classical memory and not in atypical memory subset, confirming dysfunction of this subset. Activated Tfh, which expressed excessive CD40L upon polyclonal stimulation, were present in patients. Incubation of B cells from healthy individuals with HBV core (HBc) or CD40L resulted in induction of inhibitory receptors FcRL4, FcRL5 and PD-1 on CD19+ cells and resulted in altered B cell phenotypes. Mechanistically, HBc binds B cells and causes proliferation specifically of FcRL5+ B cell subset. Our results provide evidence that HBV directly causes upregulation of inhibitory pathways in B cells resulting in an accumulation of atypical B cells that lack anti-HBs function.

Expression profiles of transcription factors for special CD4+ T-cell subsets in peripheral blood mononuclear cells from patients with hepatitis B virus infection

This study is to characterize the transcription factor expression profiles for the peripheral CD4 T-cell subsets, and analyze its associations with the clinical measures of the hepatitis B virus (HBV) infection.Totally 275 subjects were included. The expression levels of transcription factors (T-bet, GATA-3, Foxp3, RORγt, and Bcl-6) in the peripheral blood mononuclear cells (PBMCs) were determined by the real-time fluorimetry quantitative PCR (FQ-PCR).Lowest expression levels of all these transcription factors were observed for the HBsAb(-) group, which were higher in the HBsAb(+) and RHB groups. The T-bet/GATA-3 ratios in the CHB and RHB groups were significantly lower than the HBsAb(-) group, whereas the RORγt/Foxp3 ratios in the AHB and RHB groups were significantly higher than the CHB and HBsAb(+) groups. Furthermore, the RORγt mRNA expression levels were significantly different among groups with different disease severities or with different alanine aminotransferase (ALT) levels. The asymptomatic carrier (AsC) group and the group with ALT ≤ 40 had the highest express level. The mRNA expression levels of T-bet, GATA-3, Foxp3, and RORγt varied along with the aspartate aminotransferase (AST) levels, with AST ≤ 40 having the highest expression levels. In addition, significant differences were observed in the transcription factor expression levels between the group with the serum HBV DNA load of (1.000-9.999) × 10 copies/mL and other groups.Expression profile of critical transcription factors for peripheral CD4 T-cell subsets may indicate clinical outcomes of HBV infection.

The Janus Face of Follicular T Helper Cells in Chronic Viral Infections

Chronic infections with non-cytopathic viruses constitutively expose virus-specific adaptive immune cells to cognate antigen, requiring their numeric and functional adaptation. Virus-specific CD8 T cells are compromised by various means in their effector functions, collectively termed T cell exhaustion. Alike CD8 T cells, virus-specific CD4 Th1 cell responses are gradually downregulated but instead, follicular T helper (T_FH) cell differentiation and maintenance is strongly promoted during chronic infection. Thereby, the immune system promotes antibody responses, which bear less immune-pathological risk compared to cytotoxic and pro-inflammatory T cell responses. This emphasis on T_FH cells contributes to tolerance of the chronic infection and is pivotal for the continued maturation and adaptation of the antibody response, leading eventually to the emergence of virus-neutralizing antibodies, which possess the potential to control the established chronic infection. However, sustained high levels of T_FH cells can also result in a less stringent B cell selection process in active germinal center reactions, leading to the activation of virus-unspecific B cells, including self-reactive B cells, and to hypergammaglobulinemia. This dispersal of B cell help comes at the expense of a stringently selected virus-specific antibody response, thereby contributing to its delayed maturation. Here, we discuss these opposing facets of T_FH cells in chronic viral infections.

Circulating CXCR5+CD4+ T cells participate in the IgE accumulation in allergic asthma

The pathogenesis of allergic asthma is primarily characterized by abnormality in immunoglobin(Ig)E pathway, suggesting a possible role for follicular helper T cells (Tfh) in the genesis of excessive IgE accumulation. The blood chemokine (C-X-C motif) receptor 5 (CXCR)5⁺CD4⁺ T cells, known as "circulating" Tfh, share common functional characteristics with Tfh cells from germinal centers. The aim of this study was to determine the phenotypes and functions of circulating CXCR5⁺CD4⁺ T cells in allergic asthmatics. Here we found the frequency of the circulating CXCR5⁺CD4⁺ T cells was raised in allergic asthma compared with healthy control (HC). Phenotypic assays showed that activated circulating CXCR5⁺CD4⁺ T cells display the key features of Tfh cells, including invariably coexpressed programmed cell death (PD)-1 and inducible costimulator (ICOS). The frequency of interleukin IL-4⁺-, IL-21⁺-producing CXCR5⁺CD4⁺ T cells was increased in allergic asthma patients compared with HC. Furthermore, sorted circulating CXCR5⁺CD4⁺ T cells from allergic asthma patients boosted IgE production in coculture assay which could be inhibited by IL-4 or IL-21 blockage. Interestingly, IL-4⁺-, IL-21⁺-CXCR5⁺CD4⁺ T cells positively correlated with total IgE in the blood. Our data indicated that circulating CXCR5⁺CD4⁺ T cells may have a significant role in facilitating IgE production in allergic asthma patients.

miR-192 suppresses T follicular helper cell differentiation by targeting CXCR5 in childhood asthma

The aim of this study was to investigate the role of miR-192 in differentiation of T follicular helper cells in childhood asthma. Blood samples were taken from eighteen children with acute asthma attacks and fifteen healthy children (HC). Quantitative real-time PCR and Western blotting were used to detect the expression levels of miR-192, C-X-C chemokine receptor type 5 (CXCR5), B-cell lymphoma 6 (BCL-6) and inducible T-cell costimulator (ICOS). The flow cytometry was performed to detect the proportion of CD4 + CXCR5+ Tfh cells on CD4 + T lymphocytes. The enzyme-linked immunosorbent assay (ELISA) was carried out to determine the plasma concentrations of total IgE and IL-21. The effect of miR-192 on the T follicular helper cells differentiation by targeting CXCR5 was determined by dual-luciferase reporter assay. Children with asthma had lower levels of miR-192 than HC. The proportion of CD4 + CXCR + Tfh cells was significantly higher in the acute asthma group than HC. Similarly, the plasma concentration of total IgE and IL-21 in the acute group markedly increased compared with the HC, and IgE concentration was positively correlated with the proportion of CD4 + CXCR5 + Tfh cells. Furthermore, the expression levels of CXCR5, Bcl-6 and ICOS were significantly higher in the acute group than in the HC. While the proportion of CD4 + CXCR5 + Tfh cells, IL-21, CXCR5, Bcl-6 and ICOS were obviously lower in the CD4 + T cells transfected with miR-192 plasmid than that in miR-192 + CXCR5 group and control group. In conclusion, miR-192 blocks the activation pathway of Tfh cells by targeting CXCR5, which is a reasonable cellular target for therapeutic intervention.

Activation of intrahepatic CD4+CXCR5+ T and CD19+ B cells is associated with viral clearance in a mouse model of acute hepatitis B virus infection

The role of immunity in the pathogenesis of acute hepatitis B virus (HBV) infection is poorly understood. The purpose of this research was to define the intrahepatic immune factors responsible for viral clearance during acute HBV infection. The model of acute HBV infection was established by hydrodynamically transfecting mice with pCDNA3.1-HBV1.3 plasmids which contained a supergenomic HBV1.3-length transgene. The frequency of CD4⁺ CXCR5⁺ T cells, CD19⁺ B cells and their surface molecules in livers, spleens and peripheral blood were detected using flow cytometry. The lymphomononuclear cells isolated from the livers of transfected mice were further stimulated by HBc-derived peptides and then the frequency and cytokine secretion of HBV-specific CD4⁺CXCR5⁺ T cells were detected. We found that the frequency of CXCR5⁺ in CD4⁺ T cells was specifically increased; the expression of PD-1 was decreased while the expression of ICOS was increased on intrahepatic CD4⁺CXCR5⁺ T cells. Although the frequency of CD19⁺ B cells was not affected, the expression of PDL-1, ICOSL and IL-21R on B cells was increased in the livers of mice. The frequency of HBV-specific CD4⁺CXCR5⁺ T cells and the production of IL-21 by intrahepatic CD4⁺CXCR5⁺ T cells of mice with acute HBV infection were increased after stimulation. Furthermore, the expression of function-related molecules of intrahepatic CD4⁺CXCR5⁺ T, including Bcl-6, CXCR5, IL-6, IL-6R, IL-21 and IL-4 in the liver was increased during acute HBV infection. In conclusion, the activation of intrahepatic CD4⁺CXCR5⁺ T cells and B cells was associated with the clearance of HBV during acute infection.

Current concepts on immunopathogenesis of hepatitis B virus infection

Hepatitis B virus (HBV) infection is a leading cause of liver damage and hepatic inflammation. Upon infection, effective antiviral responses by CD8+ T cells, CD4+ T cells, Natural killer (NK) cells, and monocytes can lead to partial or complete eradication of the viral infection. To date, many studies have shown that the production of inhibitory cytokines such as Interleukin 10 (IL-10), Transforming growth factor beta (TGF-β), along with dysfunction of the dendritic cells (DCs), and the absence of efficient innate immune responses could lead to T cell exhaustion, development of persistent infection, and inability to eradicate the viral infection from liver. Understanding the immunopathogenesis of the virus could be useful in providing further insights toward novel strategies in the eradication of HBV infection.

Effect of follicular helper T cells on the pathogenesis of asthma

Follicular helper T (TFH) cells are considered to be a separate T helper cell subset, specifically to help memory B cell participate in humoral immunity. It has been reported that there is an association between the imbalance of TFH function and certain autoimmune diseases. However, to the best of our knowledge, the effect of TFH cells on the process of bronchial asthma has not been investigated. The aim of the present study was to investigate the associated markers of TFH cells in bronchial asthma-induced mice. In the current study, sensitized and long-term challenges induced a mouse asthmatic model and were used to investigate the associated markers of TFH cells in the pathogenesis of asthma. The results demonstrated that B cell lymphoma 6, inducible T-cell costimulator (ICOS), ICOS ligand, C-X-C chemokine receptor type 5 (CXCR5) and interleukin (IL)-21 protein and mRNA expression levels were higher in the asthma group, as compared with the control group. Furthermore, the ratio of cluster of differentiation (CD) 4⁺CXCR5⁺/CD4⁺ and CD4⁺CXCR5⁺ICOS⁺/CD4⁺CXCR5⁺ was significantly increased in the asthma group. The results of the current study suggest that TFH cells and associated markers may have a role in the pathogenesis of chronic bronchial asthma.

Expression of programmed cell death1 in T follicular helper cells is regulated by prostaglandin E2 secreted by HBV-infected HepG2.2.1.5 cells

The present study aimed to investigate the distribution of T follicular helper (Tfh)-cell subsets in patients with hepatitis B virus (HBV) and determine the underlying mechanism of HBV regulation of Tfh cells. The frequency of peripheral blood Tfh subsets was analyzed using flow cytometry. The expression level of programmed cell death‑1 (PD‑1) and prostaglandin E2 (PGE2) was quantified using reverse transcription‑quantitative polymerase chain reaction and western blotting. The PGE2 level in culture supernatant was detected using enzyme‑linked immunosorbent assay. A Transwell chamber was used to co‑culture Tfh cells with HepG2 and HepG2.2.1.5. The percentage of inducible T‑cell costimulator (ICOS)+ and total Tfh cells was high at the immune activation (IA) group; however, it was reduced in the immune tolerance (IT), responders with HBsAg seroconversion (RP) and healthy control (HC) groups. The percentage of PD‑1+ Tfh cells was significantly higher in IA and IT compared with RP and HC. The ratio of PD‑1+/total Tfh cells was positively correlated with the load of HBV DNA; therefore, this ratio may act as an indicator for HBV replication. The expression level of PD‑1 in Tfh cells was higher in the HepG2.2.1.5 co‑cultured group compared with the HepG2 group, this may be due to the high PGE2 expression level in HBV‑infected HepG2.2.1.5 cells. The findings of the present study revealed an imbalanced distribution of PD‑1+ Tfh cells in patients with HBV at different immune phases. Additionally, HBV may upregulate the expression of PD‑1 in Tfh cells by promoting HepG2.2.1.5 to secret PGE2. Identifying the effect of HBV on Tfh‑cell subsets is crucial for improving immuno-based therapy for HBV.

The Role of CD4+ T Follicular Helper Cells in HIV Infection: From the Germinal Center to the Periphery

T follicular helper cells (TFh) are key components of the adaptive immune system; they are primarily found in germinal centers (GCs) where their interaction with B cells supports humoral immune responses and efficient antibody production. They are defined by the expression of CXC receptor 5, program death-1, ICOS, and secretion of IL-21. Their differentiation is regulated by B-cell lymphoma 6. The relationship and function of circulating TFh to bona fide TFh resident in the GC is much debated. HIV infection impacts the TFh response with evidence of aberrant TFh function observed in acute and chronic infection. Effective TFh responses are associated with the development of broadly neutralizing antibody responses to HIV and may be important for viral control. In addition, TFh are preferentially infected and act as a key reservoir for latent HIV infection. This review explores recent developments in our understanding of TFh differentiation, regulation, function, and the relationship between cTFh and those in GCs, and the complex interaction between TFh and HIV infection.

Phenotype and function of CXCR5+CD45RA-CD4+ T cells were altered in HBV-related hepatocellular carcinoma and elevated serum CXCL13 predicted better prognosis

The present study reveals an immunological characterization of circulating and tumor-infiltrating T follicular helper cells (Tfh), namely CXCR5⁺CD45RA⁻CD4⁺ T cells, and their related cytokines in hepatitis B virus-related hepatocellular carcinoma (HCC) patients. In HCC patients, circulating Tfh cells showed a CCR7⁺ and/or ICOS⁺ phenotype with increased Th2-like cells and decreased Th1-like and Th17-like subsets. Although the bulk frequency of circulating Tfh cells was not altered in HCC patients, the frequency of infiltrated CXCR5⁺CD45RA⁻CD4⁺ CD3⁺cells was higher in tumor than in para-tumor tissues, and Th1-like cells were the predominant phenotype. Circulating Tfh cells in HCC patients were defective in the production of IL-21 in vitro, which was in accordance with lower IL-21 levels in tumor tissues than in para-tumor tissues. Serum CXCL13 was increased in HCC patients and associated with recurrence-free survival after hepatectomy. This was confirmed in an additional HCC cohort of 111 patients with up to 5 years follow-up. Immunohistochemical staining indicated that the percentage of CXCR5⁺ or CXCL13⁺ cells was higher in poorly differentiated than in well-differentiated tumors. In conclusion, patients with HBV-related HCC showed altered phenotypes and impaired function of Tfh cells or subpopulations. CXCL13 could be a potential biomarker for predicting recurrence in HCC patients after hepatectomy.

Production of Autoantibodies in Chronic Hepatitis B Virus Infection Is Associated with the Augmented Function of Blood CXCR5+CD4+ T Cells

T follicular helper cells (Tfh) provide help to B cells to support their activation, expansion and differentiation. However, the role of Tfh cells in chronic HBV infection is poorly defined. The aim of this research was to examine the function of Tfh cells and whether they are involved in HBV related disease. Blood CXCR5+CD4+T cells and B cells in 85 patients with chronic HBV infection (HBV patients) and health controls (HC) were examined by flow cytometry. The molecule expression in blood CXCR5+CD4+ T cells was detected by real-time PCR. Blood CXCR5+CD4+ T cells and B cells were co-cultured and the production of Ig and cytokines was detected by ELISA. Autoantibodies were detected by indirect immunofluorescence and immunospot assay. We found that blood CXCR5+CD4+ T cells in patients with chronic HBV infection (HBV patients) expressed higher level of activation related molecules and cytokines than that from health controls (HC).In HBV patients, the frequency of blood CXCR5+CD4+ T cells was significantly correlated with serum ALT and AST. We also found that blood CXCR5+CD4+ T cells from HBV patients could induce B cells to secret higher level of immunoglobulin than that from HC. Several autoantibodies, including ANA, ss-A, ss-B, Scl-70, Jo-1, ect, were indeed positive in 65% HBV patients. Among HBV patients, expression of function related molecules was significantly higher in blood CXCR5+CD4+ T cells from patients with autoantibodies than that without autoantibodies. Our research indicated that blood CXCR5+CD4+ T cells from HBV patients were over activated and show augmented capacity to help B cells for antibody secreting, which might correlated with liver inflammation and the production of autoantibodies in extrahepatic manifestations.

Interleukin-7 in Patients With Chronic Hepatitis B May Have Effect on T Follicular Helper Cells and Specific Cellular Immunity

BACKGROUND

In patients with chronic hepatitis B (CHB), the relation of interkeukin-7 (IL-7) to either the T follicular helper cells (Tfh cells) or to a specific cellular immune response is not clear.

OBJECTIVES

The present study aims to explore the possible relationship of IL-7 to Tfh cells and to hepatitis B virus (HBV)-specific cellular immune response in patients with CHB.

METHODS

Ninety-one adult patients with CHB were divided into groups A, B, and C, according to the patients' IL-7 levels (low, medium, and high). Tfh cells and HBV-specific cytotoxic T lymphocytes (CTLs) were detected with flow cytometry; IL-7 and IL-21 were determined with a double antibody sandwich enzyme-linked immunosorbent assay; and HBV DNA was determined by using a real-time fluorescent quantitative polymerase chain reaction.

RESULTS

The results showed that the levels of IL-7, Tfh cells, IL-21, and HBV-specific CTLs of patients in group C were significantly higher than those of patients in group B, (P < 0.01 for each comparison) and that the levels of these four parameters of patients in group B were significantly higher than those of the patients in group A (P < 0.01 for each comparison). Meanwhile, the level of HBV DNA of the patients in group C was significantly lower than that of the patients in group B (P < 0.01), and that of the patients in group B was significantly lower than that of the patients in group A (P < 0.05). Multiple linear regression analyses showed that IL-7, Tfh cells, IL-21, and HBV-specific CTL might have effects on HBV DNA and that only the HBV-specific CTL had an independent effect on HBV DNA (P < 0.01). IL-7, Tfh cells, and IL-21 showed independent effects on HBV-specific CTL (P < 0.05, P < 0.01, and P < 0.01).

CONCLUSIONS

This study suggests that the IL-7 level of CHB patients may be related to Tfh cells. In CHB patients, IL-7 possibly increases the level of Tfh cells and HBV-specific cellular immune responses and thereby reduces the HBV DNA level.

T follicular helper cells in patients with acute schistosomiasis

Background

The role of T follicular helper (Tfh) cells in schistosome infection is not fully defined. In a previous study, a higher frequency of circulating PD-1⁺CXCR5⁺CD4⁺ Tfh cells was observed in patients with chronic schistosomiasis relative to healthy controls (HCs) and it correlated positively with the level of soluble egg antigen (SEA) specific antibodies in serum. However, the function of Tfh cells in patients with acute schistosomiasis remains elusive; this was investigated in the present study.

Methods

The frequency of circulating Tfh cells and the expression of inducible T cell co-stimulator (ICOS), programmed cell death 1 (PD-1) and B cell subsets were analyzed in 12 patients with acute schistosomiasis and 10 HCs by flow cytometry. The expression of Bcl6, c-Maf and IL-21 mRNA were detected by quantitative real-time reverse transcriptase PCR (qRT-PCR). The concentration of serum IL-21 and IgG specific to Schistosoma japonicum antigen were then determined by enzyme linked immunosorbent assay (ELISA). Correlations between PD-1⁺CXCR5⁺CD4⁺ Tfh cells, memory B cells and IgG specific to S. japonicum were analyzed by Spearman’s rank correlation.

Results

The frequency of PD-1⁺CXCR5⁺CD4⁺ Tfh and memory B cells was increased in acute schistosomiasis patients relative to HCs. Moreover, the levels of IL-21 in serum and the expression of IL-21 mRNA were higher in acute schistosomiasis patients. However, there was no significant correlation between PD-1⁺CXCR5⁺CD4⁺ Tfh cells, memory B cells and IgG specific to S. japonicum antigen in patients with acute schistosomiasis.

Conclusions

PD-1⁺CXCR5⁺CD4⁺ Tfh cells in peripheral blood are involved in the immune response of patients with acute schistosomiasis. Understanding the immunological mechanism is helpful for the development of vaccination strategies to control schistosomiasis.

Molecular mechanisms of HBeAg in persistent HBV infection

PURPOSE

The aim of this study is to investigate the T-lymphocyte subpopulation and expression of programmed cell death-1 (PD-1), toll-like receptor (TLR)3, TLR4, and interferon (INF)-γ to illustrate the relationship between hepatitis B e antigen (HBeAg) and persistent hepatitis B virus (HBV) infection.

METHODS

Blood was taken from normal subjects into anticoagulation tubes to separate peripheral blood mononuclear cells (PBMCs). The PBMCs were divided into four groups and cultured with various concentrations of HBeAg for 72 h. Changes in the T-cell subset were analyzed through cell counting by flow cytometry, and expression of TLR3, TLR4, and PD-1 was assessed by flow cytometry and Western blot. The concentration of IFN-γ was analyzed using enzyme-linked immunospot (ELISPOT) experiments.

RESULTS

PBMCs were stimulated with various concentrations of HBeAg for 72 h and assayed by flow cytometry to determine CD4+ and CD8+ cell counts. The relative frequencies of CD4+ and CD8+ subpopulations and the CD4+/CD8+ ratio decreased compared with the control group, and T-cell impairment was significantly associated with higher HBeAg load. TLR3, TLR4, and PD-1 protein expression was assessed using flow cytometry and Western blotting. Expression of TLR3, TLR4, and PD-1 increased with increasing concentration of HBeAg. ELISPOT experiments were used to determine the concentration of IFN-γ. IFN-γ production in treatment groups was lower than in the control group. Comparing IFN-γ production in treatment groups, IFN-γ production in PBMCs stimulated with high dose of HBeAg was lower than for those stimulated with low-dose HBeAg.

CONCLUSIONS

HBeAg can inhibit proliferation of lymphocytes, increase TLR3, TLR4, and PD-1 expression, and decrease IFN-γ production. This may be one of the molecular mechanisms of HBV immune tolerance.

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

Hepatitis B e antigen (HBeAg) seroconversion constitutes a significant milestone in the treatment of HBeAg-positive patients with chronic hepatitis B (CHB), but studies have yet to identify the specific humoral immune mechanisms behind the process or any accurate markers that can determine the virus-host immune status and, thereby, predict the degree of HBeAg seroconversion achievable. In the present longitudinal study, higher frequencies of circulating CXCR5(+)CD4(+) T cells and CD19(+)CD38(+) B cells were found in peginterferon-α treated HBeAg-positive CHB patients in whom HBeAg seroconversion had been achieved. What's more, both cell types peaked at 24 weeks for the HBeAg seroconversion group, while showing only a slight variation in the HBeAg non-seroconversion group. In addition, circulating CXCR5(+)CD4(+) T cells and hepatitis B surface antigens (HBsAg) were assessed at 24 weeks and 12 weeks, respectively, and the use of their ratio was explored in terms of its ability to predict HBeAg seroconversion.

CONCLUSION

Dysfunction of the humoral immune response mediated by CXCR5(+)CD4(+) T cells is associated with the failure of HBeAg seroconversion. The CXCR5(+)CD4(+) T cells/HBsAg ratio is an ideal marker for predicting HBeAg seroconversion in CHB patients.

Can follicular helper T cells be targeted to improve vaccine efficacy?

The success of most vaccines relies on the generation of antibodies to provide protection against subsequent infection; this in turn depends on a robust germinal centre (GC) response that culminates in the production of long-lived antibody-secreting plasma cells. The size and quality of the GC response are directed by a specialised subset of CD4 ⁺ T cells: T follicular helper (Tfh) cells. Tfh cells provide growth and differentiation signals to GC B cells and mediate positive selection of high-affinity B cell clones in the GC, thereby determining which B cells exit the GC as plasma cells and memory B cells. Because of their central role in the production of long-lasting humoral immunity, Tfh cells represent an interesting target for rational vaccine design.

Association of Inducible T Cell Costimulator Polymorphisms with Susceptibility and Outcome of Hepatitis B Virus Infection in a Chinese Han Population

Inducible T cell costimulator (ICOS) functions to regulate cell-cell signalling, immune responses and cell proliferation. ICOS single nucleotide polymorphism (SNP) may affect protein expression and functions. This study investigated the association of ICOS SNPs with hepatitis B virus (HBV) infection and outcome in a Chinese population. A total of 1290 Chinese Han individuals were enrolled, including 63 asymptomatic HBV carriers, 220 chronic hepatitis B patients (CHB), 249 HBV-related liver cirrhosis patients (LC), 108 patients with HBV-related hepatocellular carcinoma (HCC), 338 patients with natural HBV clearance and 312 healthy subjects (as controls). DNA samples from these subjects were genotyped for four ICOS SNPs (rs11883722, rs10932029, rs1559931 and rs4675379) using TaqMan SNP Genotyping Assay and analysed. The data showed that genotype and allele frequencies of ICOS SNPs in cases and controls followed the Hardy-Weinberg distribution. The CC genotype of rs4675379 was higher in patients with HBV infection (including AC, CHB, LC and HCC) than in patients with HBV clearance (P = 0.006). Furthermore, the genotype 'GA' and the minor allele 'A' of rs1559931 were associated with a decreased HCC susceptibility (P < 0.001). Haplotype analysis data showed that 'GC' haplotype in block 2 (rs1559931 and rs4675379) had a lower frequency in patients than in HBV-cleared subjects (P = 0.034), although its overall frequency was only 1.6%. Our study found that ICOS rs1559931 SNP was associated with decreased HBV-related HCC risk in the studied Chinese Han population, except for patients with natural clearance of HBV.

Higher Frequency of CD4+CXCR5+ICOS+PD1+ T Follicular Helper Cells in Patients With Infectious Mononucleosis

Follicular helper T (Tfh) cells are recognized as a distinct CD4helper T cell subset, and mainly dysregulated in the autoimmune disease, whether it plays a role in the infectious mononucleosis (IM) diseases is unknown. In this study, we found that the CD4CXCR5 Tfh cells were not significantly changed, but the CD4CXCR5ICOS and CD4CXCR5ICOSPD1 Tfh subsets were significantly increased in the IM patients, and all these cells were significantly changed after antiviral therapy. Second, only the numbers of CD4CXCR5ICOSPD1 Tfh cells correlated with the Epstein-Barr virus (EBV) DNA load, negatively correlated with the numbers of naive B cells and amount of IL-21, and positively correlated with the numbers of plasma cells, memory B cells, and atypical lymphocytes. Third, the frequency of CD4CXCR5ICOSPD1 Tfh subset was significantly higher in lymphadenectasis or hepatosplenomegaly patients, and associated with the level of alanine aminotransferase (ALT). All together, our findings discovered this CD4CXCR5ICOSPD1 Tfh cell subset might play an important role in the pathogenesis of IM.

Innate and Adaptive Immune Regulation During Chronic Viral Infections

Chronic viral infections represent a unique challenge to the infected host. Persistently replicating viruses outcompete or subvert the initial antiviral response, allowing the establishment of chronic infections that result in continuous stimulation of both the innate and adaptive immune compartments. This causes a profound reprogramming of the host immune system, including attenuation and persistent low levels of type I interferons, progressive loss (or exhaustion) of CD8(+) T cell functions, and specialization of CD4(+) T cells to produce interleukin-21 and promote antibody-mediated immunity and immune regulation. Epigenetic, transcriptional, posttranscriptional, and metabolic changes underlie this adaptation or recalibration of immune cells to the emerging new environment in order to strike an often imperfect balance between the host and the infectious pathogen. In this review we discuss the common immunological hallmarks observed across a range of different persistently replicating viruses and host species, the underlying molecular mechanisms, and the biological and clinical implications.

CCR7(lo)PD-1(hi) CXCR5(+) CD4(+) T cells are positively correlated with levels of IL-21 in active and transitional cystic echinococcosis patients

Background

In our study, we investigated whether circulating T follicular helper (Tfh) and the related cytokines are involved in human cystic echinococcosis (CE).

Methods

A total of 64 patients with CE and 30 healthy controls were enrolled in this study. Percentages of CCR7^loPD-1^hi cells within CXCR5⁺ CD4⁺ T cells (circulating Tfh cells) were detected by flow cytometry. Levels of IL-21 and IL-4 in peripheral blood were detected by cytometric bead array. The mRNA expression of IL-21, IL-4, Bcl-6, and Blimp-1 in peripheral blood mononuclear cells (PBMCs) were measured by real-time PCR. Levels of IgG1, IgG2, IgG3, and IgG4 in the patients’ sera were measured using enzyme-linked immunosorbent assay.

Results

Percentages of circulating Tfh cells were significantly increased in the CE1, CE2, and CE3 groups (p < 0.05). The concentrations of IL-21 and IL-4 in the serum were significantly increased in CE1, CE2, and CE3 groups (p < 0.05). IL-21 was positively correlated with circulating Tfh cells in CE3 group (r = 0.779, p < 0.05). The mRNA levels of IL-21, IL-4, and Bcl-6 were increased in CE1, CE2, and CE3 groups. Levels of IgG1 and IgG4 in patients’ sera were increased in CE1, CE2, and CE3 groups. Levels of IgG2 and IgG3 were increased in CE4-5 group. Additionally, after stimulation with hydatid fluid in vitro, the levels of circulating Tfh cells, IL-21 and IL-4 in PBMCs isolated from CE patients were significantly increased (p < 0.05).

Conclusions

The levels of circulating Tfh and related cytokines were significantly increased in CE patients, suggesting that they are involved in human CE.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1156-9) contains supplementary material, which is available to authorized users.

T Follicular Helper Cell-Dependent Clearance of a Persistent Virus Infection Requires T Cell Expression of the Histone Demethylase UTX

Epigenetic changes, including histone methylation, control T cell differentiation and memory formation, though the enzymes that mediate these processes are not clear. We show that UTX, a histone H3 lysine 27 (H3K27) demethylase, supports T follicular helper (Tfh) cell responses that are essential for B cell antibody generation and the resolution of chronic viral infections. Mice with a T cell-specific UTX deletion had fewer Tfh cells, reduced germinal center responses, lacked virus-specific immunoglobulin G (IgG), and were unable to resolve chronic lymphocytic choriomeningitis virus infections. UTX-deficient T cells showed decreased expression of interleukin-6 receptor-α and other Tfh cell-related genes that were associated with increased H3K27 methylation. Additionally, Turner Syndrome subjects, who are predisposed to chronic ear infections, had reduced UTX expression in immune cells and decreased circulating CD4(+) CXCR5(+) T cell frequency. Thus, we identify a critical link between UTX in T cells and immunity to infection.

Regulatory and Helper Follicular T Cells and Antibody Avidity to Simian Immunodeficiency Virus Glycoprotein 120

T follicular regulatory cells (TFR) are a suppressive CD4(+) T cell subset that migrates to germinal centers (GC) during Ag presentation by upregulating the chemokine receptor CXCR5. In the GC, TFR control T follicular helper cell (TFH) expansion and modulate the development of high-affinity Ag-specific responses. In this study, we identified and characterized TFR as CXCR5(+)CCR7(-) "follicular" T regulatory cells in lymphoid tissues of healthy rhesus macaques, and we studied their dynamics throughout infection in a well-defined animal model of HIV pathogenesis. TFR were infected by SIVmac251 and had comparable levels of SIV DNA to CXCR5(-)CCR7(+) "T zone" T regulatory cells and TFH. Contrary to the SIV-associated TFH expansion in the chronic phase of infection, we observed an apparent reduction of TFR frequency in cell suspension, as well as a decrease of CD3(+)Foxp3(+) cells in the GC of intact lymph nodes. TFR frequency was inversely associated with the percentage of TFH and, interestingly, with the avidity of the Abs that recognize the SIV gp120 envelope protein. Our findings show changes in the TFH/TFR ratio during chronic infection and suggest possible mechanisms for the unchecked expansion of TFH cells in HIV/SIV infection.

Higher Frequency of Circulating PD-1(high) CXCR5(+)CD4(+) Tfh Cells in Patients with Chronic Schistosomiasis

The current knowledge of immunological responses to schistosomiasis is insufficient for the development of vaccine and therapies. The role of T follicular helper (Tfh) cells in schistosome infections is not fully defined. The frequency of circulating Tfh cells and serum cytokine levels were analyzed in 11 patients with chronic schistosomiasis and 10 healthy controls (HC), who reside in an endemic area for Schistosomiasis japonicum. Significantly higher frequencies of circulating CXCR5(+) CD4(+) Tfh cells and higher expression levels of ICOS and PD-1 in CXCR5(+) CD4(+) Tfh cells were observed in patients with chronic schistosomiasis compared to HC. The levels of IL-21 in serum and the expression of IL-21 mRNA were higher in chronic schistosomiasis patients than in HC. Moreover, the frequency of circulating PD-1(high) CXCR5(+) CD4(+) Tfh cells positively correlated with the levels of IL-21 in serum from patients with chronic schistosomiasis. A positive correlation was also found between the frequency of PD-1(high) CXCR5(+) CD4(+) Tfh cells and the levels of soluble egg antigen (SEA)-specific antibodies in serum samples from the patient group. Our study is the first regarding Tfh cells in chronic human schistosomiasis and the finding indicate that PD-1(high) CXCR5(+) CD4(+)Tfh cells might play an important role in the production of specific antibodies in schistosomiasis. This study contributes to the understanding of immune response to schistosomiasis and may provide helpful support in vaccine development.

IL-33 Enhances Humoral Immunity Against Chronic HBV Infection Through Activating CD4(+)CXCR5(+) TFH Cells

This study aimed to investigate the potential effect of interleukin 33 (IL-33) on humoral responses to hepatitis B virus (HBV) and the possible mechanisms underlying the action of IL-33 in regulating follicular helper T (TFH) cells. The impact of IL-33 treatment on the levels of serum HBV DNA, HBsAg, HBeAg, HBsAb, and HBeAb, as well as the frequencies of CD4(+)CXCR5(+) TFH cells in wild-type HBV transgenic (HBV-Tg) mice and in a transwell coculture of HepG2.2.15 with IL-33-treated peripheral blood mononuclear cells (PBMCs) were determined. Furthermore, the gene transcription profiles in IL-33-treated TFH cells were determined by microarrays. IL-33 treatment significantly reduced the levels of serum HBV DNA, HBsAg, and HBeAg, but increased the levels of HBsAb and HBeAb in HBV-Tg mice, accompanied by increased frequency of splenic infiltrating CD4(+)CXCR5(+) TFH cells in HBV-Tg. Similarly, coculture of HepG2.2.15 cells with IL-33-treated PBMCs reduced the levels of HBV DNA, HBsAg, and HBeAg, but increased the levels of HBsAb and HBeAb. Microarray analyses indicated that IL-33 significantly modulated the transcription of many genes involved in regulating TFH activation and differentiation. Our findings suggest that IL-33 may activate TFH cells, promoting humoral responses to HBV during the pathogenic process.

The expression of TLR-9, CD86, and CD95 phenotypes in circulating B cells of patients with chronic viral hepatitis B or C before and after antiviral therapy

AIMS

This study aimed to assess the differential expression of specific B cell subtypes in patients with chronic viral hepatitis.

METHODS

The frequencies of differential expression of specific B cell subtypes in patients with chronic viral hepatitis and healthy controls were assessed by flow cytometry using monoclonal antibodies specific for CD38, CD27, CD86, CD95, TLR-9, and IgD. The effect of adefovir treatment on B cell subsets in HBV patients was determined. The values of clinical parameters in the patients were also measured.

RESULTS

The frequency of CD86+ B cells was not significantly different in chronic HBV patients but was higher in HCV patients compared with that in healthy controls. CD95 and IgD levels were lower in HBV and HCV patients than in healthy controls. A significant negative correlation occurred between the proportion of CD95+ B cells and HBV DNA viral load. The frequency of TLR-9 on the B cells in HBV and HCV patients was higher compared with that of healthy controls. After treatment with adefovir, the frequency of CD95 and IgD expressed on B cells was increased in HBV patients.

CONCLUSIONS

Activated B cells and exhausted B cells homeostasis were commonly disturbed in HBV and HCV patients.

Constitutively altered frequencies of circulating follicullar helper T cell counterparts and their subsets in rheumatoid arthritis

Introduction

Circulating CD4 T cells expressing CXCR5, ICOS and/or PD-1 are counterparts of follicular helper T cells (Tfh). There are three subpopulations of circulating Tfh (cTfh): CXCR5 + CXCR3 + CCR6- (Tfh-Th1), CXCR5 + CXCR3-CCR6- (Tfh-Th2) and CXCR5 + CXCR3-CCR6+ (Tfh-Th17). Our objective was to study the B cell helping capacity of cTfh subsets, and examine their frequency in Rheumatoid Arthritis (RA) patients, together with the frequency of circulating plasmablasts (CD19 + CD20-CD38^high).

Methods

Peripheral blood was drawn from RA patients with active disease (RA-a, DAS28 >2.6) (n = 17), RA in remission (RA-r, DAS28 <2.6) (n = 17) and healthy controls (HC) (n = 34). cTfh and plasmablast frequencies were determined by flow cytometry. Cocultures of sorted CD4 + CXCR5+ T cell subpopulations were established with autologous CD19 + CD27- naïve B cells of HC, and concentrations of IgG, A and M were measured in supernatants.

Results

Isolated Tfh-Th2 and Tfh-Th17 but not Tfh-Th1 cells, induced naïve B cells to secrete IgG and IgA. The frequency of CXCR5+ cells gated for CD4+ T cells was not different among HC, RA-a and RA-r. In contrast, both RA-a and RA-r patients demonstrated an increased frequency of CD4 + CXCR5 + ICOS+ T cells and augmented (%Tfh-Th2 + %Tfh-Th17)/%Tfh-Th1 ratio as compared with HC. In addition, RA-a but not RA-r patients, showed an increased frequency of circulating plasmablasts.

Conclusion

Both RA-a and RA-r patients demonstrate an increased frequency of cTfh and overrepresentation of cTfh subsets bearing a B cell helper phenotype, suggesting that altered germinal center dynamics play a role in RA pathogenesis. In contrast, only RA-a patients show an increased proportion of circulating plasmablasts.

Follicular helper T lymphocytes in health and disease

A correct antibody response requires the participation of both B and T lymphocytes and antigen presenting cells. In this review we address the role of follicular helper T lymphocytes (T_FH) in this reaction. We shall focus on the regulation of their development and function in health and disease. T_FH can be characterized on the basis of their phenotype and the pattern of secretion of cytokines. This fact is useful to study their participation in the generation of antibody deficiency in primary immunodeficiency diseases such as common variable immunodeficiency, X-linked hyper IgM syndrome or X-linked lymphoproliferative disease. Increased numbers of T_FH have been demonstrated in several autoimmune diseases and are thought to play a role in the development of autoantibodies. In chronic viral infections caused by the human immunodeficiency virus, hepatitis B or C virus, increased circulating T_FH have been observed, but their role in the protective immune response to these agents is under discussion. Likewise, an important role of T_FH in the control of some experimental protozoan infections has been proposed, and it will be important to assess their relevance in order to design effective vaccination strategies.

Role of interleukin-21 in HBV infection: friend or foe?

Interleukin (IL)-21, a cytokine produced by activated CD4(+) T cells, has broad pleiotropic actions that affect the functions of a variety of lymphoid cells. The roles of IL-21 in modulating immunity to infections are currently being defined. Notably, IL-21-mediated cellular and humoral immune responses play an important role in determining the outcome of viral infection. This article reviews the current knowledge on the critical role of IL-21 in hepatitis B virus (HBV) infection. As a competent intermediary, IL-21 derived from virus-specific CD4(+) T cells plays key roles in sustaining CD8(+) T cells and promoting B-cell responses that are essential for effective viral control. However, as a mediator of inflammation, IL-21 is also involved in the development of HBV-induced liver cirrhosis and exacerbating liver injury. Overall, the current data point to IL-21 as an immunomodulatory cytokine in HBV infection. Immunotherapeutic strategies aimed at optimizing the beneficial effects of IL-21 in HBV infection may prove to be a rigorous challenge in the future, as they should foster the strengths of IL-21 while circumventing potential drawbacks.

Decreased frequencies of circulating CD4⁺ T follicular helper cells associated with diminished plasma IL-21 in active pulmonary tuberculosis

Background

Circulating T follicular helper (Tfh) cells represent a distinct subset of CD4⁺ T cells and are important in immunity to infections. Although they have been shown to play a role in experimental models of tuberculosis infection, their role in human tuberculosis remains unexplored.

Aims/Methodology

To determine the distribution of circulating Tfh cells in human TB, we measured the frequencies of Tfh cells exvivo and following TB - antigen or polyclonal stimulation in pulmonary TB (PTB; n = 30) and latent TB (LTB; n = 20) individuals, using the markers CXCR5, PD-1 and ICOS.

Results

We found that both exvivo and TB - antigen induced frequencies of Tfh cell subsets was significantly lower in PTB compared to LTB individuals. Similarly, antigen induced frequencies of Tfh cells expressing IL-21 was also significantly lower in PTB individuals and this was reflected in diminished circulating levels of IL-21 and IFNγ. This was not accompanied by diminished frequencies of activated or memory B cell subsets. Finally, the diminution in frequency of Tfh cells in PTB individuals was dependent on IL-10, CTLA-4 and PD-L1 invitro.

Conclusions

Thus, PTB is characterized by adiminution in the frequency of Tfh cell subsets.

Increased numbers of CD5+CD19+CD1dhighIL-10+ Bregs, CD4+Foxp3+ Tregs, CD4+CXCR5+Foxp3+ follicular regulatory T (TFR) cells in CHB or CHC patients

BACKGROUND

IL-10+ regulatory B (Bregs), CD4+Foxp3+ regulatory T (Tregs), and CD4+CXCR5+Foxp3+ follicular regulatory T (TFR) cells regulate the progression of infection disease. This study aimed at examining how those cells associated with the development of chronic hepatitis B (CHB) and chronic hepatitis C (CHC) in a Chinese population.

METHODS

The numbers of circulating IL-10+ Bregs, Tregs and TFR cells in 31 CHC, 58 CHB patients and 22 healthy controls (HC) were examined by flow cytometry. The potential association of those cells with clinical measures was analyzed.

RESULTS

The numbers of CD5+CD19+CD1dhighIL-10+ Bregs, Tregs and TFR cells and the levels of serum IL-10, IFN-γ and IL-2 in the CHB, and IL-10 and IFN-γ in the CHC patients were significantly higher than that in the HC (p<0.05). Furthermore, the numbers of circulating IL-10+ Bregs and the levels of serum IL-10, but not other cytokines tested were positively correlated with the levels of serum HBV DNA and ALT in the HBeAg- CHB patients as well as HCV RNA and ALT in CHC patients. Additionally, the numbers of circulating TFR cells were positively correlated with the levels of serum HBV DNA and ALT in the CHB patients as well as HCV RNA and ALT in the CHC patients.

CONCLUSIONS

Increased numbers of circulating IL-10+ Bregs and TFR cells are associated with poor virus eradication and liver injury in CHB and CHC patients. Furthermore, the levels of serum IL-10 is associated with the hepatic flares.

Decreased frequencies of circulating follicular helper T cell counterparts and plasmablasts in ankylosing spondylitis patients Naïve for TNF blockers

Follicular helper T cells (Tfh), localized in lymphoid organs, promote B cell differentiation and function. Circulating CD4 T cells expressing CXCR5, ICOS and/or PD-1 are counterparts of Tfh. Three subpopulations of circulating CD4+CXCR5+ cells have been described: CXCR3+CCR6- (Tfh-Th1), CXCR3-CCR6+ (Tfh-Th17), and CXCR3-CCR6- (Tfh-Th2). Only Tfh-Th17 and Tfh-Th2 function as B cell helpers. Our objective was to study the frequencies of circulating Tfh (cTfh), cTfh subsets and plasmablasts (CD19+CD20-CD27+CD38high cells), and the function of cTfh cells, in patients with Ankylosing Spondylitis (AS). To this end, peripheral blood was drawn from healthy controls (HC) (n = 50), AS patients naïve for TNF blockers (AS/nb) (n = 25) and AS patients treated with TNF blockers (AS/b) (n = 25). The frequencies of cTfh and plasmablasts were determined by flow cytometry. Cocultures of magnetically sorted CD4+CXCR5+ T cells with autologous CD19+CD27- naïve B cells were established from 3 AS/nb patients and 3 HC, and concentrations of IgG, A and M were measured in supernatants. We obseved that AS/nb but not AS/b patients, demonstrated decreased frequencies of circulating CD4+CXCR5+ICOS+PD-1+ cells and plasmablasts, together with a decreased (Tfh-Th17+Tfh-Th2)/Tfh-Th1 ratio. The amounts of IgG and IgA produced in cocultures of CD4+CXCR5+ T cells with CD19+CD27- B cells of AS/nb patients were significantly lower than observed in cocultures established from HC. In summary, AS/nb but not AS/b patients, demonstrate a decreased frequency of cTfh and plasmablasts, and an underrepresentation of cTfh subsets bearing a B helper phenotype. In addition, peripheral blood CD4+CXCR5+ T cells of AS/nb patients showed a decreased capacity to help B cells ex vivo.

A higher frequency of CD4⁺CXCR5⁺ T follicular helper cells in adult patients with minimal change disease

Background. T follicular helper (TFH) cells are involved in the humoral immune responses. This study is aimed at examining the frequencies of different subsets of CD4⁺CXCR5⁺ TFH cells in adult patients with minimal change disease (MCD). Methods. A total of 27 patients and 14 healthy controls (HC) were characterized for the levels of sera cytokines, inducible T-cell costimulator (ICOS), and programmed death 1 (PD-1) of positive TFH cells by flow cytometry. The level of sera IL-21 was examined; 24 h urinary protein and eGFR were calculated. The potential correlation between the frequency of different subsets of TFH cells and the values of clinical measures in MCD patients were analyzed. Results. The frequency of circulating CD4⁺CXCR5⁺, CD4⁺CXCR5⁺ICOS⁺, and CD4⁺CXCR5⁺PD-1⁺ TFH cells and the levels of sera IL-17A, IFN-γ, IL-2, IL-10, IL-4, and IL-21 were significantly higher in MCD patients (P < 0.05) than that in the HC group. Furthermore, the percentages of circulating CD4⁺CXCR5⁺ TFH cells were negatively correlated with the values of eGFR (r = −0.4849, P < 0.05) and the percentages of CD4⁺CXCR5⁺PD-1⁺ TFH cells were correlated positively with the levels of serum IL-21 (r = 0.6137, P < 0.05) and 24 h urinary protein (r = 0.1410, P < 0.05) in those patients. Also, the percentages of CD4⁺CXCR5⁺ICOS⁺ TFH cells were correlated positively with the levels of serum IL-21 (r = 0.6201, P < 0.05) and 24 h urinary protein (r = 0.7519, P < 0.05). Following standard therapies, the percentages of circulating CD4⁺CXCR5⁺, CD4⁺CXCR5⁺PD-1⁺, and CD4⁺CXCR5⁺ICOS⁺ TFH cells and the levels of serum IL-21 were significantly reduced, but the levels of serum IL-4 and IL-10 were increased (P < 0.05). Conclusions. A higher frequency of CD4⁺CXCR5⁺ TFH cells that existed in adult patients with MCD could be new target for intervention of MCD.

Genetic polymorphisms of CXCR5 and CXCL13 are associated with non-responsiveness to the hepatitis B vaccine

A cohort based study has been undertaken to investigate the possible association of genetic polymorphisms in genes functionally related to follicular T helper (TfH) cells with non-responsiveness to hepatitis B virus (HBV) vaccination. A total of 24 single nucleotide polymorphisms (SNPs) in 6 TfH related genes (CXCR5, ICOS, CXCL13, IL-21, BCL6 and CD40L) were investigated in 20 non-responders and 45 responders to HBV vaccination. Genetic association analysis revealed that three SNPs (rs497916, rs3922, rs676925) in CXCR5 and one SNP (rs355687) in CXCL13 were associated with hepatitis B vaccine efficacy. In addition, significantly unbalanced distributions of two haplotypes, defined by three SNPs (rs497916, rs3922, rs676925) within CXCR5, were also seen between non-responders and responders. Furthermore, we demonstrated that the rs3922 "GG" genotype was associated with higher levels of CXCR5 than the "AG" and "AA" genotype in a group of healthy volunteers. A dual luciferase report assay was used to confirm that the "G" allele in rs3922 may lead to higher gene expression than the "A" allele, implicating that rs3922 might be a functional SNP affecting CXCR5 expression. These results indicated that polymorphism associated changes in CXCR5 expression in TfH cells may be associated with non-responsiveness to hepatitis B vaccination.

Frequency of CD4+CXCR5+ TFH cells in patients with hepatitis b virus-associated membranous nephropathy

The frequency of different subsets of CD4(+)CXCR5(+) TFH cells and serum cytokine levels were analyzed in a total of 14 patients with newly diagnosed hepatitis B virus-associated membranous nephropathy (HBV-MN), 12 individuals with immune-tolerant HBV infection (HBV-IT) and 12 healthy controls (HC). Serum cytokine levels were measured before and 10-12 weeks after treatment. Significantly higher frequency of CD4(+)CXCR5(+), CD4(+)CXCR5(+)ICOS(+) and CD4(+)CXCR5(+)PD-1(+) TFH cells, and higher serum levels of IL-17A, IFN-γ, IL-2, IL-10, IL-4 and IL-21 were detected in HBV-MN patients compared to the HC. The percentage of CD4(+)CXCR5(+) TFH cells and serum IL-21 level in HBV-MN patients were also higher than the HBV-IT. The percentage of CD4(+)CXCR5(+) TFH cell was negatively correlated with the value of eGFR, and the percentage of CD4(+)CXCR5(+)ICOS(+) TFH cells was positively correlated with the 24-h urinary protein concentration. Notably, the percentage of CD4(+)CXCR5(+)PD-1(+) TFH cells was positively correlated with serum IL-21 level and 24-h urinary protein concentration. Treatment with prednisone or/and immunosuppressive drugs significantly reduced the frequency of CD4(+)CXCR5(+), CD4(+)CXCR5(+)PD-1(+) TFH cells and serum IL-21 level, but increased IL-4 and IL-10 levels in the patients. CD4(+)CXCR5(+) TFH cells, especially CD4(+)CXCR5(+)PD-1(+) TFH cells may participate in the pathogenesis of HBV-MN.

Increased frequency of circulating follicular helper T cells in children with hand, foot, and mouth disease caused by enterovirus 71 infection

Enterovirus 71 (EV71) is a major causative agent of hand, foot, and mouth disease (HFMD) in children. The role of T follicular helper (TFH) cells in EV71-infected children remains unclear in regulating humoral immunity. The frequency of circulating ICOS^high/PD-1^highCXCR5⁺CD4⁺ TFH cells in the children with mild and severe EV71 infection and healthy controls (HC) was detected by flow cytometry, respectively. IL-21 and IL-6 mRNA expression and their serum levels, Bcl-6 mRNA expression, and specific neutralizing antibodies against EV71 (NAb-EV71) were measured. In the acute stage of patients with EV71 infection, increased frequencies of circulating TFH cells with ICOS^high and PD-1^high expression in the mild and severe patients were observed, and the positive correlations among the frequencies of circulating TFH cells and the serum levels of IL-21, IL-6, and NAb-EV71 titres were detected, respectively. Moreover, the expressions of IL-6 and IL-21 mRNA in PBMCs from patients were also significantly higher than those of HC. However, further analysis did not reveal any significant differences between mild and severe patients. These data indicate a role of TFH cells and associated cytokines in modulating the humoral response during the pathogenesis of EV71 infection.

Adaptive response in hepatitis B virus infection

Hepatitis B virus (HBV) is a major cause of acute and chronic liver inflammation worldwide. The immune response against the virus represents a key factor in determining infection outcome, in terms of both viral clearance and the perpetuation of liver damage. Significant advances have recently been achieved regarding the functions of antiviral CD8+ T cells, leading to a better understanding of their abnormalities during chronic infection as well as the pathways to be manipulated to reverse the immune impairment of chronic infection. In this review, we aimed to analyse the patterns of adaptive immunity that develop during acute infection and the profiles in chronic infection. In addition to CD8+ T cells, which are the best-described subset to date, we reviewed and commented on the direct and indirect roles of CD4+ T cells and B cells.

Follicular helper T cells promote liver pathology in mice during Schistosoma japonicum infection

Following Schistosoma japonicum (S. japonicum) infection, granulomatous responses are induced by parasite eggs trapped in host organs, particular in the liver, during the acute stage of disease. While excessive liver granulomatous responses can lead to more severe fibrosis and circulatory impairment in chronically infected host. However, the exact mechanism of hepatic granuloma formation has remained obscure. In this study, we for the first time showed that follicular helper T (Tfh) cells are recruited to the liver to upregulate hepatic granuloma formation and liver injury in S. japonicum-infected mice, and identified a novel function of macrophages in Tfh cell induction. In addition, our results showed that the generation of Tfh cells driven by macrophages is dependent on cell–cell contact and the level of inducible costimulator ligand (ICOSL) on macrophages which is regulated by CD40–CD40L signaling. Our findings uncovered a previously unappreciated role for Tfh cells in liver pathology caused by S. japonicum infection in mice.

Schistosomiasis is a chronic helminthic disease that affects approximately 200 million people. After S. japonicum infection, parasite eggs are trapped in host liver and granulomas are induced to form around eggs. Severe granuloma subsequently results in serious liver fibrosis and circulatory impairment chronically. It is important to fully elucidate the mechanism of the granuloma formation. Here, we show that Tfh cells play a novel role of promoting the hepatic granuloma formation and liver injury, and identified a novel function of macrophages in Tfh cells induction in S. japonicum-infected mouse model. In addition, we show that the generation of Tfh cells driven by macrophages is cell–cell contact dependent and regulated by CD40-CD40L signaling. Our findings revealed a novel role and mechanism of macrophages in Tfh cell generation and the liver pathogenesis in S. japonicum-infected mouse model.

CD4+CXCR5+ follicular helper T cells in salivary gland promote B cells maturation in patients with primary Sjogren's syndrome

OBJECTIVE

To examine amount of CD4+CXCR5+Tfh cells and B cells subsets in salivary gland and peripheral blood from patients with primary Sjogren's syndrome (pSS) and to analyze whether the frequency of CD4+CXCR5+Tfh cells is associated with pSS pathologic process.

METHODS

The percentages of CD4+CXCR5+Tfh cells and B cell subsets were examined by flow cytometry. B-lymphocyte chemoattraetant (BLC; also called CXCL13), IL-21, IL-6 from the serum of pSS patients was assessed by polymerase chain reaction-enzyme-linked immunosorbent assay (ELISA).

RESULTS

The percentages of CD4+CXCR5+Tfh cells in peripheral blood were increased in pSS patients, but decreased after treatment with glucocorticoid and/or immunosuppressive drugs. Abnormal B cell subsets appeared in salivary and peripheral blood of pSS patients. The frequency of salivary CD4+CXCR5+Tfh cells was positively correlated with CD19+CD27+ memory B cells and CD19+CD27high plasma cells. Also increase of salivary CD19+CD27high plasma cells was positively associated with serum ANA titer of pSS patients.

CONCLUSIONS

CD4+CXCR5+Tfh cells are significantly increased in salivary and peripheral blood in pSS patients with aberrant CD19+CD27+ memory B cells and CD19+CD27high plasma cells, suggesting that CD4+CXCR5+Tfh cells may contribute to the pathogenesis of pSS by promoting the maturation of B cells.

Increased levels of IL-21 responses are associated with the severity of liver injury in patients with chronic active hepatitis B

Interleukin-21 (IL-21) participates in tissue damage in various immune-mediated diseases. Its role in the pathogenesis of chronic active hepatitis B (CAHB) has not been clarified. The frequency of circulating IL-21(+) T cells and the levels of serum and intrahepatic IL-21 have been characterized in 70 CAHB patients, 32 inactive carrier (IC), 18 chronic hepatitis C (CHC) and 20 healthy controls (HC). Their potential association with liver injury was analysed. The percentages of IL-21(+) CD3(+) CD8(-) and IL-21(+) CD3(+) CD8(+) T cells and the levels of serum IL-21 in CAHB patients were significantly higher than that in the IC, CHC patients and HC (P < 0.001) and were correlated positively with the levels of serum alanine aminotransferase (ALT, r = 0.424, P < 0.001; r = 0.392, P = 0.001) and aspartate aminotransferase (AST, r = 0.388, P = 0.001; r = 0.329, P = 0.005) in CAHB patients, respectively. The levels of IL-21 expression in the liver tissues were associated significantly with increased degrees of inflammation and fibrosis in CAHB patients (P < 0.01 or P < 0.05). Our findings suggest that aberrant IL-21 responses may be associated with the progression of CHB.

Tfh and plasma cells are correlated with hypergammaglobulinaemia in patients with autoimmune hepatitis

BACKGROUND

This study aimed at examining the numbers of different subsets of circulating Tfh and B cells in patients with new onset autoimmune hepatitis (AIH).

METHODS

A total of 17 patients with new onset AIH and 17 age-/gender-matched healthy controls (HC) were examined for the numbers of ICOS(+) , PD-1(+) and IL-21(+) Tfh cells, CD27(+) , CD38(+) , CD95(+) , CD86(+) and IL-10(+) B cells were quantified by flow cytometry. The concentrations of serum IL-21 and IL-10 were examined.

RESULTS

In comparison with that in the HC, significantly increased numbers of circulating CD38(+) , CD86(+) or CD95(+) B cells, ICOS(+) and PD-1(+) Tfh cells and increased levels of serum IL-21, but reduced numbers of CD27(+) , IL-10(+) B cells were detected in the patients. The concentrations of serum IL-21 and IL-10 were positively correlated with the numbers of CD4(+) CXCR5(+) TFH and CD19(+) CD5(+) CD1d(+) B cells respectively. The numbers of ICOS(+) or PD-1(+) Tfh cells were correlated positively with CD86(+) or CD95(+) B cells in those patients respectively. The numbers of CD38(+) B cells, ICOS(+) or PD-1(+) Tfh cells were correlated positively with the concentrations of serum IgG or IgM in the patients respectively; the concentrations of serum IL-21 were correlated positively with serum IgG, IgA and IgM and the concentrations of serum IL-10 were correlated negatively with serum IgG and IgM in the patients.

CONCLUSION

Circulating activated Tfh and plasma cells may be associated with hypergammaglobulinaemia during the pathogenic process of AIH in humans.