Libo Tang

High serum IL-21 levels after 12 weeks of antiviral therapy predict HBeAg seroconversion in chronic hepatitis B

BACKGROUND & AIMS Interleukin-21 (IL-21) stimulates T cell and B cell responses and plays a role in control of chronic viral infections. The role of IL-21 in chronic hepatitis B virus (HBV) infection is not understood. METHODS Serum IL-21 levels were measured by enzyme immunoassay in 75 HBeAg-positive chronic hepatitis B (CHB) patients undergoing telbivudine treatment. The findings were validated in 103 patients from a separate clinical trial of telbivudine. A complete response to telbivudine was defined as having both HBeAg seroconversion and serum HBV-DNA level <300 copies/ml by treatment week 52. The proportions of T-cells producing IL-21 and/or expressing programmed death 1 (PD-1) in peripheral blood mononuclear cells were assessed longitudinally during treatment by intracellular cytokine staining and flow cytometry. RESULTS Median serum IL-21 levels at treatment week 12 were significantly higher in patients who did achieve vs. patients who did not achieve a complete response in both the initial (128.4 vs. 69.2 pg/ml, p=0.003) and the validation (142.2 vs. 89.9 pg/ml, p=0.004) trials. Serum levels of IL-21 (p=0.005) or HBV-DNA (p=0.003) levels at treatment week 12 independently predicted HBeAg seroconversion in the first year of treatment. The decrease in PD-1 expression on CD4(+) and CD8(+) T cells during the first 12 weeks on telbivudine treatment was not correlated with changes in IL-21 concentrations. CONCLUSIONS Serum IL-21 levels may be a biomarker for HBeAg seroconversion, and may contribute to individualization of antiviral therapy in HBeAg-positive CHB. IL-21 may also have a role in immunotherapy for CHB.

Circulating chemokine (C‐X‐C Motif) receptor 5+CD4+ T cells benefit hepatitis B e antigen seroconversion through IL‐21 in patients with chronic hepatitis B virus infection

Given the clinical significance of hepatitis B e antigen (HBeAg) seroconversion in chronic hepatitis B virus (HBV) infection, it is critical to elucidate the mechanisms regulating this process. In the present study, we found that the frequency of circulating chemokine (C‐X‐C motif) receptor 5 (CXCR5)+CD4+ T cells was higher in patients who had achieved HBeAg seroconversion in both cross‐sectional (P < 0.001) and longitudinal (P = 0.009) studies. These cells were able to produce a significantly higher level of intracellular interleukin 21 (IL‐21) after stimulation with HBV peptides in patients with telbivudine‐induced HBeAg seroconversion (P = 0.007). Furthermore, sorted CXCR5+CD4+ T cells from HBeAg seroconverters boosted a higher frequency of antibody against hepatitis B e antigen (anti‐HBe)‐secreting B cells in coculture assay (P = 0.011). Of note, the increase in frequency of anti‐HBe‐secreting B cells was abrogated by soluble recombinant IL‐21 receptor‐Fc chimera (P = 0.027), whereas exogenous recombinant IL‐21 enhanced this effect (P = 0.043). Additionally, circulating CXCR5+CD4+ T cells shared similar phenotypic markers, and were positively correlated in frequency with, splenic follicular T helper cells. Conclusion: Circulating CXCR5+CD4+ T cells, by producing IL‐21, may have a significant role in facilitating HBeAg seroconversion in patients with chronic HBV infection. (Hepatology 2013;58:1277–1286)

Chemokine (C‐X‐C motif) ligand 13 promotes intrahepatic chemokine (C‐X‐C motif) receptor 5+ lymphocyte homing and aberrant B‐cell immune responses in primary biliary cirrhosis

The serologic hallmark of primary biliary cirrhosis (PBC) is the presence of high titer, and specific anti-mitochondrial antibodies (AMA). Interestingly, although there is no global immune defect in patients with PBC, there is widespread dysregulated B cell function, including increased sera levels of IgM and enhanced B cell responses to CpG stimulation. The mechanisms involved in this B cell dysfunction have remained unknown. To address this issue, we focused on identifying the frequencies of B cell subsets in patients with PBC and the mechanisms that lead to B cell dysregulation, including the relationships with CXCR5+CD4+T cells. Herein we report that elevations of both serum and intrahepatic IL-21 were found in patients with PBC and, in particular, promoted B cell proliferation, STAT3 phosphorylation and AMA production in vitro. More importantly, upon stimulation with rPDC-E2, CXCR5+CD4+T cells in PBC produced higher levels of IL-21 than healthy controls. Additionally, sorted CXCR5+CD4+T cells increased production of AMA by autologous CD19+B cells. Indeed, elevated expression of intrahepatic CXCL13, a key chemokine of CXCR5+ cells, was uniquely found within the portal tracts in PBC, accompanied by infiltrates of CD4+, CXCR5+, CD19+, and CD38+ cells. In conclusion, CXCL13 promotes aggregation of CD19+B cells and CXCR5+CD4+T cells, which directs the aberrant AMA response via IL-21. These data have implications for potential immunotherapy and also reflect the unique lymphoid biology in the liver of PBC.The serological hallmark of primary biliary cirrhosis (PBC) is the presence of high titer and specific antimitochondrial antibodies (AMAs). Although there is no global immune defect in patients with PBC, there is widespread dysregulated B‐cell function, including increased sera levels of immunoglobulin M and enhanced B‐cell responses to cytosine‐phosphate‐guanine stimulation. The mechanisms involved in this B‐cell dysfunction have remained unknown. To address this issue, we focused on identifying the frequencies of B‐cell subsets in patients with PBC and the mechanisms that lead to B‐cell dysregulation, including the relationships with chemokine (C‐X‐C motif) receptor 5 (CXCR5)+CD4+T cells. Herein, we report that elevations of both serum and intrahepatic interleukin‐21 (IL‐21) were found in patients with PBC and, in particular, promoted B‐cell proliferation, signal transducer and activator of transcription 3 phosphorylation and AMA production in vitro. More important, upon stimulation with recombinant E2 subunit of pyruvate dehydrogenase complex, CXCR5+CD4+T cells in PBC produced higher levels of IL‐21 than healthy controls. Additionally, sorted CXCR5+CD4+T cells increased production of AMAs by autologous CD19+B cells. Indeed, elevated expression of intrahepatic chemokine (C‐X‐C motif) ligand 13 (CXCL13), a key chemokine of CXCR5+ cells, was uniquely found within the portal tracts in PBC, accompanied by infiltrates of CD4+, CXCR5+, CD19+, and CD38+ cells. Conclusion: CXCL13 promotes aggregation of CD19+B cells and CXCR5+CD4+T cells, which directs the aberrant AMA response by IL‐21. These data have implications for potential immunotherapy and also reflect the unique lymphoid biology in liver of PBC. (Hepatology 2015;61:1998‐2007)

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.Cellular & Molecular Immunology advance online publication, 3 November 2014; doi:10.1038/cmi.2014.109

Transforming growth factor β-activated kinase 1 transcriptionally suppresses hepatitis B virus replication.

Hepatitis B Virus (HBV) replication in hepatocytes is restricted by the host innate immune system and related intracellular signaling pathways. Transforming growth factor β-activated kinase 1 (TAK1) is a key mediator of toll-like receptors and pro-inflammatory cytokine signaling pathways. Here, we report that silencing or inhibition of endogenous TAK1 in hepatoma cell lines leads to an upregulation of HBV replication, transcription, and antigen expression. In contrast, overexpression of TAK1 significantly suppresses HBV replication, while an enzymatically inactive form of TAK1 exerts no effect. By screening TAK1-associated signaling pathways with inhibitors and siRNAs, we found that the MAPK-JNK pathway was involved in TAK1-mediated HBV suppression. Moreover, TAK1 knockdown or JNK pathway inhibition induced the expression of farnesoid X receptor α, a transcription factor that upregulates HBV transcription. Finally, ectopic expression of TAK1 in a HBV hydrodynamic injection mouse model resulted in lower levels of HBV DNA and antigens in both liver and serum. In conclusion, our data suggest that TAK1 inhibits HBV primarily at viral transcription level through activation of MAPK-JNK pathway, thus TAK1 represents an intrinsic host restriction factor for HBV replication in hepatocytes.

Interleukin 21 Reinvigorates the Antiviral Activity of Hepatitis B Virus (HBV)–Specific CD8+ T Cells in Chronic HBV Infection

BACKGROUND Strategies that target functional recovery of exhausted hepatitis B virus (HBV)-specific CD8+ T cells are beneficial for viral control, but the potential for interleukin 21 (IL-21) to rescue CD8+ T-cell function is not well understood. METHODS We investigated the effect of IL-21 on CD8+ T-cell responses by phenotypic and functional analysis of samples from patients with chronic HBV infection and a mouse model with HBV expression. RESULTS IL-21 promoted the proliferative capacity of HBV-specific CD8+ T cells and down-regulated expression of the inhibitory receptors programmed death 1 and T-cell immunoglobulin domain and mucin domain 3. Additionally, IL-21 boosted the production of interferon-γ, granzyme B, and CD107a in HBV-specific CD8+ T cells and enhanced the cytolytic activity of CD8+ T cells against HepG2.2.15 cells. Notably, an HBV mouse model established from IL-21 receptor knockout mice showed significantly decreased frequency of HBV-specific CD8+ T cells and increased levels of serum hepatitis B surface antigen (HBsAg). Meanwhile, administration of recombinant mouse IL-21 in an HBV mouse model established from wild-type mice resulted in enhanced functionality of HBV-specific CD8+ T cells and accelerated HBsAg clearance. CONCLUSIONS IL-21 enhances the antiviral effect of HBV-specific CD8+ T cells, suggesting that it may contribute to viral clearance in chronic HBV infection.

IL-21 receptor signaling is essential for control of hepatocellular carcinoma growth and immunological memory for tumor challenge

ABSTRACT Hepatocellular carcinoma (HCC) is a typical inflammation-associated cancer. IL-21 regulates both innate and adaptive immune responses and has key roles in antitumor and antiviral responses. However, the role of IL-21 in HCC development is poorly defined. In the current study, we explored the role of IL-21R signaling in HCC growth by using IL-21R knockout mice and HCC mouse models. We discovered that IL-21R signaling deficiency promoted HCC growth in tumor-bearing mice. We showed that IL-21R deletion reduced T cells infiltration and activation as well as their function but increased the accumulation of myeloid-derived suppressor cells in tumor tissues to enhance HCC growth. Furthermore, loss of IL-21R signaling in tumor-bearing mice resulted in an imbalance of the systemic immune system characterized by decreased antitumor immune cells and increased immunosuppressive cells in the spleen and lymph nodes. In addition, we revealed that IL-21R signaling is critical for the expansion of antitumor immune cells in the memory immune response to tumor rechallenge. Finally, we showed that the transcriptional levels of IL-21 in the peritumoral region and IL-21R within the tumor are associated with survival and recurrence of HCC patients. In conclusion, our study demonstrates that IL-21R signaling is essential for controlling the development of HCC and immunological memory response to tumor challenge.

Evidence for the association between IgG‐antimitochondrial antibody and biochemical response to ursodeoxycholic acid treatment in primary biliary cholangitis

Antimitochondrial antibody (AMA) is considered the serological hallmark of primary biliary cholangitis (PBC), while data regarding the profile of AMA during ursodeoxycholic acid (UDCA) treatment are scarce. Here, we assessed the influence of UDCA treatment on titers of AMA and factors relevant to its production.

Chemokine (C-X-C motif) ligand 13 promotes intrahepatic chemokine (C-X-C motif) receptor 5+ lymphocyte homing and aberrant B-cell immune responses in primary biliary cirrhosis: HEPATOLOGY, Vol. XX, No. X, 2015

The serologic hallmark of primary biliary cirrhosis (PBC) is the presence of high titer, and specific anti-mitochondrial antibodies (AMA). Interestingly, although there is no global immune defect in patients with PBC, there is widespread dysregulated B cell function, including increased sera levels of IgM and enhanced B cell responses to CpG stimulation. The mechanisms involved in this B cell dysfunction have remained unknown. To address this issue, we focused on identifying the frequencies of B cell subsets in patients with PBC and the mechanisms that lead to B cell dysregulation, including the relationships with CXCR5+CD4+T cells. Herein we report that elevations of both serum and intrahepatic IL-21 were found in patients with PBC and, in particular, promoted B cell proliferation, STAT3 phosphorylation and AMA production in vitro. More importantly, upon stimulation with rPDC-E2, CXCR5+CD4+T cells in PBC produced higher levels of IL-21 than healthy controls. Additionally, sorted CXCR5+CD4+T cells increased production of AMA by autologous CD19+B cells. Indeed, elevated expression of intrahepatic CXCL13, a key chemokine of CXCR5+ cells, was uniquely found within the portal tracts in PBC, accompanied by infiltrates of CD4+, CXCR5+, CD19+, and CD38+ cells. In conclusion, CXCL13 promotes aggregation of CD19+B cells and CXCR5+CD4+T cells, which directs the aberrant AMA response via IL-21. These data have implications for potential immunotherapy and also reflect the unique lymphoid biology in the liver of PBC.The serological hallmark of primary biliary cirrhosis (PBC) is the presence of high titer and specific antimitochondrial antibodies (AMAs). Although there is no global immune defect in patients with PBC, there is widespread dysregulated B‐cell function, including increased sera levels of immunoglobulin M and enhanced B‐cell responses to cytosine‐phosphate‐guanine stimulation. The mechanisms involved in this B‐cell dysfunction have remained unknown. To address this issue, we focused on identifying the frequencies of B‐cell subsets in patients with PBC and the mechanisms that lead to B‐cell dysregulation, including the relationships with chemokine (C‐X‐C motif) receptor 5 (CXCR5)+CD4+T cells. Herein, we report that elevations of both serum and intrahepatic interleukin‐21 (IL‐21) were found in patients with PBC and, in particular, promoted B‐cell proliferation, signal transducer and activator of transcription 3 phosphorylation and AMA production in vitro. More important, upon stimulation with recombinant E2 subunit of pyruvate dehydrogenase complex, CXCR5+CD4+T cells in PBC produced higher levels of IL‐21 than healthy controls. Additionally, sorted CXCR5+CD4+T cells increased production of AMAs by autologous CD19+B cells. Indeed, elevated expression of intrahepatic chemokine (C‐X‐C motif) ligand 13 (CXCL13), a key chemokine of CXCR5+ cells, was uniquely found within the portal tracts in PBC, accompanied by infiltrates of CD4+, CXCR5+, CD19+, and CD38+ cells. Conclusion: CXCL13 promotes aggregation of CD19+B cells and CXCR5+CD4+T cells, which directs the aberrant AMA response by IL‐21. These data have implications for potential immunotherapy and also reflect the unique lymphoid biology in liver of PBC. (Hepatology 2015;61:1998‐2007)

CXCL13 Promotes Intrahepatic CXCR5+ Lymphocyte Homing and Aberrant B Cell Immune Responses in Primary Biliary Cirrhosis

The serologic hallmark of primary biliary cirrhosis (PBC) is the presence of high titer, and specific anti-mitochondrial antibodies (AMA). Interestingly, although there is no global immune defect in patients with PBC, there is widespread dysregulated B cell function, including increased sera levels of IgM and enhanced B cell responses to CpG stimulation. The mechanisms involved in this B cell dysfunction have remained unknown. To address this issue, we focused on identifying the frequencies of B cell subsets in patients with PBC and the mechanisms that lead to B cell dysregulation, including the relationships with CXCR5+CD4+T cells. Herein we report that elevations of both serum and intrahepatic IL-21 were found in patients with PBC and, in particular, promoted B cell proliferation, STAT3 phosphorylation and AMA production in vitro. More importantly, upon stimulation with rPDC-E2, CXCR5+CD4+T cells in PBC produced higher levels of IL-21 than healthy controls. Additionally, sorted CXCR5+CD4+T cells increased production of AMA by autologous CD19+B cells. Indeed, elevated expression of intrahepatic CXCL13, a key chemokine of CXCR5+ cells, was uniquely found within the portal tracts in PBC, accompanied by infiltrates of CD4+, CXCR5+, CD19+, and CD38+ cells. In conclusion, CXCL13 promotes aggregation of CD19+B cells and CXCR5+CD4+T cells, which directs the aberrant AMA response via IL-21. These data have implications for potential immunotherapy and also reflect the unique lymphoid biology in the liver of PBC.The serological hallmark of primary biliary cirrhosis (PBC) is the presence of high titer and specific antimitochondrial antibodies (AMAs). Although there is no global immune defect in patients with PBC, there is widespread dysregulated B‐cell function, including increased sera levels of immunoglobulin M and enhanced B‐cell responses to cytosine‐phosphate‐guanine stimulation. The mechanisms involved in this B‐cell dysfunction have remained unknown. To address this issue, we focused on identifying the frequencies of B‐cell subsets in patients with PBC and the mechanisms that lead to B‐cell dysregulation, including the relationships with chemokine (C‐X‐C motif) receptor 5 (CXCR5)+CD4+T cells. Herein, we report that elevations of both serum and intrahepatic interleukin‐21 (IL‐21) were found in patients with PBC and, in particular, promoted B‐cell proliferation, signal transducer and activator of transcription 3 phosphorylation and AMA production in vitro. More important, upon stimulation with recombinant E2 subunit of pyruvate dehydrogenase complex, CXCR5+CD4+T cells in PBC produced higher levels of IL‐21 than healthy controls. Additionally, sorted CXCR5+CD4+T cells increased production of AMAs by autologous CD19+B cells. Indeed, elevated expression of intrahepatic chemokine (C‐X‐C motif) ligand 13 (CXCL13), a key chemokine of CXCR5+ cells, was uniquely found within the portal tracts in PBC, accompanied by infiltrates of CD4+, CXCR5+, CD19+, and CD38+ cells. Conclusion: CXCL13 promotes aggregation of CD19+B cells and CXCR5+CD4+T cells, which directs the aberrant AMA response by IL‐21. These data have implications for potential immunotherapy and also reflect the unique lymphoid biology in liver of PBC. (Hepatology 2015;61:1998‐2007)