Interleukin-21 receptor signaling promotes metabolic dysfunction-associated steatohepatitis-driven hepatocellular carcinoma by inducing immunosuppressive IgA+ B cells.

BACKGROUND: Dysregulation of immune surveillance is tightly linked to the development of metabolic dysfunction-associated steatohepatitis (MASH)-driven hepatocellular carcinoma (HCC); however, its underlying mechanisms remain unclear. Herein, we aimed to determine the role of interleukin-21 receptor (IL-21R) in MASH-driven HCC. METHODS: The clinical significance of IL-21R was assessed in human HCC specimens using immunohistochemistry staining. Furthermore, the expression of IL-21R in mice was assessed in the STAM model. Thereafter, two different MASH-driven HCC mouse models were applied between IL-21R-deficient mice and wild type controls to explore the role of IL-21R in MASH-driven HCC. To further elucidate the potential mechanisms by which IL-21R affected MASH-driven HCC, whole transcriptome sequencing, flow cytometry and adoptive lymphocyte transfer were performed. Finally, flow cytometry, enzyme-linked immunosorbent assay, immunofluorescent staining, chromatin immunoprecipitation assay and western blotting were conducted to explore the mechanism by which IL-21R induced IgA+ B cells. RESULTS: HCC patients with high IL-21R expression exhibited poor relapse-free survival, advanced TNM stage and severe steatosis. Additionally, IL-21R was demonstrated to be upregulated in mouse liver tumors. Particularly, ablation of IL-21R impeded MASH-driven hepatocarcinogenesis with dramatically reduction of lipid accumulation. Moreover, cytotoxic CD8+ T lymphocyte activation was enhanced in the absence of IL-21R due to the reduction of immunosuppressive IgA+ B cells. Mechanistically, the IL-21R-STAT1-c-Jun/c-Fos regulatory axis was activated in MASH-driven HCC and thus promoted the transcription of Igha, resulting in the induction of IgA+ B cells. CONCLUSIONS: IL-21R plays a cancer-promoting role by inducing IgA+ B cells in MASH-driven hepatocarcinogenesis. Targeting IL-21R signaling represents a potential therapeutic strategy for cancer therapy.

Interleukin (IL)-21 and IL-21 receptor expression in peripheral T and B cells of patients with breast cancer.

IL-21 is a cytokine with versatile antitumor and pro-tumorigenic activities. It is mainly produced by CD4+ T cells and B cells are one of its pivotal targets. In this study, we assessed and compared the expression of IL-21 by CD4+ T cells and the IL-21 receptor (IL-21R) on B cells in the peripheral blood of women with breast cancer and healthy individuals. Blood samples were taken from both patients and controls. Mononuclear cells were seperated using Ficoll-Hypaque density gradient centrifugation. These isolated cells were then stained with either anti-CD19/anti-IL-21R or anti-CD4/anti-IL-21 antibodies and analyzed using flow cytometry. The results showed that there was no significant difference in the percentage of IL-21R+ B cells and IL-21+CD4+ T cells between patients and controls. However, the percentage of CD4+ T cells decreased significantly in patients with breast cancer (P=0.003). This decline was observed from the early stage and before lymph node (LN) involvement. In comparison to the control group, IL-21R+ B cells were relatively lower in patients with stages I+II and those with fewer than 4 involved LNs. The intensity of IL-21 expression in T cells was associated with HER2 expression (P=0.029). Furthermore, we found that the majority of IL-21R+ B cells exhibited a naïve phenotype and most of IL-21+CD4+ T cells did not produce IFN-γ or IL-17. In conclusion, breast cancer from the early stages leads to a significant reduction in the proportion of peripheral CD4+ T cells. However, we did not find a significant change in IL-21 and its receptor expression during disease progression.

A novel engineered IL-21 receptor arms T-cell receptor-engineered T cells (TCR-T cells) against hepatocellular carcinoma.

Strategies to improve T cell therapy efficacy in solid tumors such as hepatocellular carcinoma (HCC) are urgently needed. The common cytokine receptor γ chain (γc) family cytokines such as IL-2, IL-7, IL-15 and IL-21 play fundamental roles in T cell development, differentiation and effector phases. This study aims to determine the combination effects of IL-21 in T cell therapy against HCC and investigate optimized strategies to utilize the effect of IL-21 signal in T cell therapy. The antitumor function of AFP-specific T cell receptor-engineered T cells (TCR-T) was augmented by exogenous IL-21 in vitro and in vivo. IL-21 enhanced proliferation capacity, promoted memory differentiation, downregulated PD-1 expression and alleviated apoptosis in TCR-T after activation. A novel engineered IL-21 receptor was established, and TCR-T armed with the novel engineered IL-21 receptors (IL-21R-TCR-T) showed upregulated phosphorylated STAT3 expression without exogenous IL-21 ligand. IL-21R-TCR-T showed better proliferation upon activation and superior antitumor function in vitro and in vivo. IL-21R-TCR-T exhibited a less differentiated, exhausted and apoptotic phenotype than conventional TCR-T upon repetitive tumor antigen stimulation. The novel IL-21 receptor in our study programs powerful TCR-T and can avoid side effects induced by IL-21 systemic utilization. The novel IL-21 receptor creates new opportunities for next-generation TCR-T against HCC.

Gene Expression in Synovium of Rotator Cuff Tear Patients Determined by RNA Sequencing.

Rotator cuff tear (RCT) is a common shoulder disorder related to pain and dysfunction. However, the pathological mechanism of RCT remains unclear. Thus, this study aims to investigate the molecular events in RCT synovium and identify possible target genes and pathways as determined by RNA sequencing (RNA-Seq). The synovial tissue was biopsied from 3 patients with RCT (RCT group) and 3 patients with shoulder instability (Control group) during arthroscopic surgery. Then, differentially expressed (DE) mRNAs, long non-coding RNAs (lncRNAs) and micro RNAs (miRNAs) were comprehensively profiled by RNA-Seq. Gene ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and competing endogenous RNA (ceRNA) network analysis were performed to identify the potential functions of these DE genes. 447 mRNAs, 103 lncRNAs and 15 miRNAs were identified differentially expressed. The DE mRNAs were highlighted in inflammatory pathway including up-regulated T cell costimulation, positive regulation of T cell activation, and T cell receptor signaling. Down-regulated fatty acid degradation pathway and 5'-AMP-activated protein kinase (AMPK) signaling in RCT group are also enriched. Validation assay showed that the expression of pro-inflammatory molecules including IL21R, CCR5, TNFSF11, and MMP11 was significantly increased in RCT group compared with Control group. CeRNA analysis further revealed lncRNA-miRNA-mRNA regulatory networks involving IL21R and TNFSF11 in RCT. Activated synovial inflammation is the remarkable event of RCT. Importantly, increased T cell activation and disordered fatty acid metabolism signaling might play a significant role. ceRNA networks involving IL21R and TNFSF11 identified could potentially control the progression of RCT. In conclusion, our findings could provide new evidence for the molecular mechanisms of RCT and might identify new therapeutic targets.

ChIP-seq analysis found IL21R, a target gene of GTF2I-the susceptibility gene for primary biliary cholangitis in Chinese Han.

AIMS: Aimed to identify a new susceptibility gene associated with primary biliary cholangitis (PBC) in Chinese Han and investigate the possible mechanism of that gene in PBC. METHODS: A total of 466 PBC and 694 healthy controls (HC) were included in our study, and genotyping GTF2I gene variants by Sequenom. CD19 + B cells were isolated for Chromatin immunoprecipitation sequencing (ChIP-seq). Additionally, MEME-ChIP was utilized to perform searches for known motifs and de novo motif discovery. The GTF2I ChIP-seq of hematopoietic cell line (K562) results were obtained from ENCODE (GSE176987, GSE177691). The Genomic HyperBrowser was used to determine overlap and hierarchal clustering between ours and ENCODE datasets. RESULTS: The frequency of the rs117026326 variant T allele was significantly higher in PBC patients than that in HC (20.26% compared with 13.89%, Pc = 1.09E-04). Furthermore, we observed an elevated proportion of GTF2I binding site located in the upstream and 5' UTR of genes in PBC in comparison with HC. Additionally, an in-depth analysis of IL21R region revealed that GTF2I might bind to the IL21R promoter to regulate the expression of the IL21R, with four peaks of GTF2I binding sites, including three increased binding sites in upstream, one increased binding site in 5' UTR. Motif analysis by MEME-ChIP uncovered five significant motifs. A significant overlap between our ChIP and GSE176987, GSE17769 were found by the Genomic HyperBroswer. CONCLUSIONS: Our study confirmed that GTF2I was associated with PBC in Chinese Han. Furthermore, our gene function analysis indicated that IL21R may be the target gene regulated by GTF2I.

The identification and expression of an interleukin-21 receptor in large yellow croaker (Larimichthys crocea).

BACKGROUND: We identified a homologue of IL-21R (LcIL-21R) in large yellow croaker (Larimichthys crocea, Lc). Our investigation focused on understanding the molecular structural features and immune function of LcIL-21R. METHODS: We cloned the LcIL-21R gene from the genome of Larimichthys crocea by RT‒PCR, and the molecular and structural characteristics of LcIL-21R were analyzed by a series of protein analysis tools. We used real-time PCR to investigate the tissue distribution of LcIL-21R, and LcIL-21R gene expression regulation was also measured in head kidney leukocytes under trivalent bacterial vaccine or poly (I:C) stimulation. RESULTS: The open reading frame (ORF) of the LcIL-21R gene is 1629 bp long and encodes a precursor protein of 542 amino acids (aa), with a 23-aa signal peptide and a 519-aa mature peptide containing four putative N-glycosylation sites. LcIL-21R has two fibronectin type III (FNIII)-like domains (D1 and D2), a transmembrane domain, and a cytoplasmic region. A conserved WSXWS motif was also found in the D2 domain. The predicted structure of the extracellular region of LcIL-21R (LcIL-21R-Ex) is highly similar to that of human IL-21R. LcIL-21R was constitutively expressed in all tissues examined, and LcIL-21R mRNA levels were increased in the head kidney and spleen upon inactivated trivalent bacterial vaccine or poly(I:C) stimulation. CONCLUSIONS: Our results suggest that LcIL-21R shares structural and functional properties with IL-21Rs found in other vertebrates, indicating its potential involvement in the IL-21-mediated immune response to pathogenic infections. These findings contribute to our understanding of the evolutionary conservation of IL-21 signaling and its role in the immune system.

Expression of Interleukin-21 and Interleukin-21 receptor in lymphocytes derived from tumor-draining lymph nodes of breast cancer.

BACKGROUND: Interleukin-21 (IL-21) is produced by various cell types inducing positive and negative effects in immunity against tumors. OBJECTIVE: To investigate the expression of IL-21 by CD4+T and IL-21 receptor (IL-21R) by B lymphocytes isolated from breast-tumor draining lymph nodes (TDLNs). METHODS: Fresh lymph node samples were obtained from 45 patients with breast cancer. To assess IL-21 expression, mononuclear cells were briefly stimulated whereas IL-21R expression was assessed in unstimulated B cells. Cells were stained with antibodies for CD4, IL-21, CD19 and IL-21R and acquired by flow cytometry. RESULTS: The frequency of IL-21+CD4+T cells did not show significant association with disease parameters. However, the geometric mean fluorescence intensity (gMFI) of IL-21 in CD4+T cells was significantly lower in patients with grade III tumor than grade I + II (P = 0.042). In non-involved LNs, the intensity of IL-21 was significantly higher in patients with stage II compared with stage III (P = 0.038) and correlated negatively with the number of involved LNs. The frequency of IL-21R+CD19+B cells was significantly higher in grade III than grade I + II (P = 0.037). CONCLUSION: The higher intensity of IL-21 in CD4+T cells showed association with good prognosticators in breast cancer and warrants further investigation of the role played by IL-21 in immunity against breast cancer.

Combined immunodeficiency with marginal zone lymphoma due to a novel homozygous mutation in IL-21R gene and successful treatment with hematopoietic stem cell transplantation.

Mutations in the interleukin-21 receptor (IL-21R) gene are recently defined as primary immunodeficiency diseases. IL-21R defects result in combined immunodeficiency by affecting the functions of innate and adaptive immune system components.A six-year-old girl was admitted to our hospital with complaints of chronic diarrhea that started after the newborn period and generalized rash over the last three months. She had severe respiratory distress due to Cytomegalovirus (CMV) pneumonia requiring mechanical ventilation and was diagnosed as combined immunodeficiency at another hospital at the age of four. Her physical examination on admission revealed erythematous rash on cheeks, extremities, gluteal region, and lymph node enlargements in cervical, axillary, and inguinal regions. CMV DNA and stool Cryptosporidium parvum were positive. Marginal zone lymphoma -negative for Epstein-Bar virus- was reported in the lymph node biopsy. Targeted next-generation sequencing Ion AmpliSeq™ primary immunodeficiency panel revealed a novel homozygous IL21R c.132delC (p.Ser45fs) mutation.This case is presented to emphasize that IL21R defects should be considered in the differential diagnosis of the patients with recurrent respiratory infections, chronic diarrhea, C. parvum infection, chronic liver disease, sclerosing cholangitis, and malignancy where early hematopoietic stem cell transplantation (HSCT) is life-saving. A total of eight cases with IL21R gene defects have been reported so far. The significance of this case is that it is the first case of malignancy among the published IL-21R deficient patients successfully treated with HSCT.

WSB1 and IL21R Genetic Variants Are Involved in Th2 Immune Responses to Ascaris lumbricoides.

Genetic and epigenetic factors are considered to be critical for host-parasite interactions. There are limited data on the role of such factors during human infections with Ascaris lumbricoides. Here, we describe the potential role of genetic factors as determinants of the Th2 immune response to A. lumbricoides in Brazilian children. Stool samples were collected from the children to detect A. lumbricoides by microscopy and peripheral blood leukocytes (PBLs) were cultured in whole blood cultures for detection of cytokines (IL-5, IL-10, and IL-13) in vitro. Levels of anti-A. lumbricoides IgE and IgG4 were measured in plasma. DNA was extracted from PBLs and genotyped using Illumina 2.5 Human Omni Beadchip. Candidate genes associated with A. lumbricoides responses were identified and SNVs in these selected genes associated with the Th2 immune response to A. lumbricoides. Haplotype, gene expression, and epigenetic analyses were done to identify potential associations with Th2 immune responses. GWAS on samples from 1,189 children identified WSB1 as a candidate gene, and IL-21R was selected as a biologically relevant linked gene for further analysis. Variants in WSB1 and IL21R were associated with markers of Th2 immune responses: increased A. lumbricoides-specific IgE and IL-5/IL-13 by PBLs from infected compared to uninfected individuals. In infected children, WSB1 but not IL21R gene expression was suppressed and increased methylation was observed in the WSB1 promoter region. This is the first study to show an association between genetic variants in WSB1 and IL21R and Th2 immune responses during A. lumbricoides infections in children. WSB1/IL21R pathways could provide a potential target for the treatment of Th2-mediated diseases.

IL-21/IL-21R Signaling Aggravated Respiratory Inflammation Induced by Intracellular Bacteria through Regulation of CD4+ T Cell Subset Responses.

The IL-21/IL-21R interaction plays an important role in a variety of immune diseases; however, the roles and mechanisms in intracellular bacterial infection are not fully understood. In this study, we explored the effect of IL-21/IL-21R on chlamydial respiratory tract infection using a chlamydial respiratory infection model. The results showed that the mRNA expression of IL-21 and IL-21R was increased in Chlamydia muridarum-infected mice, which suggested that IL-21 and IL-21R were involved in host defense against C. muridarum lung infection. IL-21R-/- mice exhibited less body weight loss, a lower bacterial burden, and milder pathological changes in the lungs than wild-type (WT) mice during C. muridarum lung infection. The absolute number and activity of CD4+ T cells and the strength of Th1/Th17 responses in IL-21R-/- mice were significantly higher than those in WT mice after C. muridarum lung infection, but the Th2 response was weaker. Consistently, IL-21R-/- mice showed higher mRNA expression of Th1 transcription factors (T-bet/STAT4), IL-12p40, a Th17 transcription factor (STAT3), and IL-23. The mRNA expression of Th2 transcription factors (GATA3/STAT6), IL-4, IL-10, and TGF-ß in IL-21R-/- mice was significantly lower than that in WT mice. Furthermore, the administration of recombinant mouse IL-21 aggravated chlamydial lung infection in C57BL/6 mice and reduced Th1 and Th17 responses following C. muridarum lung infection. These findings demonstrate that IL-21/IL-21R may aggravate chlamydial lung infection by inhibiting Th1 and Th17 responses.

IL-21 Promotes Intestinal Memory IgA Responses.

The role of IL-21, produced mainly by Th17 cells and T follicular helper cells, has been intensively investigated in B cell differentiation and Ab class switch. However, how IL-21 regulates memory IgA+ B cell development and memory IgA responses in the intestines is still not completely understood. In this study, we found the total IgA+ B cells as well as CD38+CD138-IgA+ memory B cells were significantly increased in intestinal lamina propria (LP) of TCRßxδ-/- mice after transfer of microbiota Ag-specific Th17 cells but not Th1 cells. Although IL-21R-/- mice or IL-17R-/- mice showed decreased Ag-specific memory IgA production in the intestines upon infection with Citrobacter rodentium, the percentage of IgA+CD38+CD138- memory B cells in Peyer's patches and LP was decreased only in IL-21R-/- mice, but not in IL-17R-/- mice, after reinfection with C. rodentium compared with wild-type mice. Blockade IL-21 in vivo suppressed intestinal C. rodentium-specific IgA production as well as IgA+CD38+CD138- memory B cells in Peyer's patches and LP. Furthermore, IL-21 significantly induced B cell IgA production in vitro, with the increased expression of genes related with class-switching and memory B cell development, including Aicda, Ski, Bmi1, and Klf2. Consistently, Aicda and Ski expression was decreased in B cells of IL-21R-/- mice after C. rodentium reinfection. In conclusion, our study demonstrated that IL-21 promotes intestinal memory IgA B cell development, possibly through upregulating differentiation-related and class switching-related genes, indicating a potential role of IL-21 in memory IgA+ B cell responses in the intestines.

Interleukin 21 (IL-21) regulates chronic allograft vasculopathy (CAV) in murine heart allograft rejection.

IL-21 is the most recently discovered common gamma-chain cytokine that promotes persistent T-cell responses in chronic infections, autoimmunity and cancer. However, the therapeutic potential of inhibiting the IL-21-BATF signaling axis, particularly in transplant rejection, remains unclear. We used heart transplant models to examine the effects of IL-21 blockade in prevention of chronic cardiac allograft vasculopathy (CAV) using genetic knock-out and therapeutic approaches. Both wild-type C57BL/6 and IL-21-/- strains acutely rejected Balb/c skin grafts and once immunized with this skin graft, rejected Balb/c heart allografts in an accelerated fashion. However, when transplanted with heart grafts from the class-II major histocompatibility complex mutant, B6bm12 mice; wild-type recipients developed CAV, while IL-21-/- recipients were protected, even at day 100 post-transplant. Similarly, BATF-/- recipients, lacking the transcription factor BATF responsible for IL-21 production, did not develop CAV in B6-bm12 heart allografts. Strikingly, in a transient treatment protocol, the development of CAV in wild-type recipients of B6-bm12 hearts allografts was blocked by the administration of IL-21 receptor fusion protein (R-Fc). Thus, we demonstrate that CAV is regulated at least in part by IL-21 signaling and its blockade by genetic approaches or therapy with IL-21R-Fc prevents CAV in mice.

Interleukin 21 Receptor/Ligand Interaction Is Linked to Disease Progression in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) displays a marked fibro-inflammatory microenvironment in which infiltrated immune cells fail to eliminate the tumor cells and often-rather paradoxically-promote tumor progression. Of special interest are tumor-promoting T cells that assume a Th17-like phenotype because their presence in PDAC tissue is associated with a poor prognosis. In that context, the role of IL-21, a major cytokine released by Th17-like cells, was assessed. In all tissue samples (n = 264) IL-21+ immune cells were detected by immunohistochemistry and high density of those cells was associated with poor prognosis. In the majority of patients (221/264), tumor cells expressed the receptor for IL-21 (IL-21R) and also a downstream target of IL-21, Blimp-1 (199/264). Blimp-1 expression closely correlated with IL-21R expression and multivariate analysis revealed that expression of both IL-21R and Blimp-1 was associated with shorter survival time of the patients. In vitro data using pancreatic tumor cells lines provided a possible explanation: IL-21 activated ERK and STAT3 pathways and upregulated Blimp-1. Moreover, IL-21 increased invasion of tumor cell lines in a Blimp-1-dependent manner. As an in vivo correlate, an avian xenograft model was used. Here again Blimp-1 expression was significantly upregulated in IL-21 stimulated tumor cells. In summary, our data showed an association of IL-21+ immune cell infiltration and IL-21 receptor expression in PDAC with poor survival, most likely due to an IL-21-mediated promotion of tumor cell invasion and enhanced colony formation, supporting the notion of the tumor-promoting abilities of the tumor microenvironment.

IL-21 Controls ILC3 Cytokine Production and Promotes a Protective Phenotype in a Mouse Model of Colitis.

Group 3 innate lymphoid cells (ILC3s) have dual roles in intestinal health, acting in both protective and pathogenic capacities, and importantly, modulations in this population of innate lymphoid cells have been implicated in inflammatory bowel disease. Further, subpopulations of ILC3s have been described as serving specific functions in maintaining homeostasis or responding to infection, and aberrant activation of one or more of these subpopulations could exacerbate inflammatory bowel disease. However, the signals that enforce the protective and pathogenic features of ILC3s are not fully elucidated. In this article, we show that IL-21, a cytokine primarily produced by CD4 T cells, acts on a subpopulation of intestinal ILC3s to promote a protective phenotype. IL-21 signaling does not affect the MHC class II-expressing ILC3 subset but promotes ILC3s that express Tbet and are poised to produce IL-22. Consistent with a protective phenotype, IL-21 deficiency dampens cytokine-induced IL-17A production. We show that exacerbated colitis develops in mice lacking the IL-21 receptor, in agreement with a protective role for IL-21 signaling on ILC3s. To our knowledge, these data reveal a novel role for IL-21 in shaping innate lymphoid cell responses in the intestine and provide one mechanism by which effector CD4 T cells can influence innate immunity.

Clinical significance and immunobiology of IL-21 in autoimmunity.

Interleukin-21 (IL-21), an autocrine cytokine predominantly produced by follicular helper T (Tfh) and T helper 17 (Th17) cells, has been proven to play an important role in the immune system, for example, by promoting proliferation and the development of Tfh and Th17 cells, balancing helper T cell subsets, inducing B cell generation and differentiation into plasma cells, and enhancing the production of immunoglobulin. These effects are mainly mediated by activation of the JAK/STAT, MAPK and PI3K pathways. Some IL-21 target genes, such as B lymphocyte induced maturation protein-1 (Blimp-1), suppressor of cytokine signaling (SOCS), CXCR5 and Bcl-6, play important roles in the immune response. Therefore, IL-21 has been linked to autoimmune diseases. Indeed, IL-21 levels are increased in the peripheral blood and tissues of patients with systematic lupus erythematosus (SLE), rheumatoid arthritis (RA), type 1 diabetes (T1D), immune thrombocytopenia (ITP), primary Sjogren's syndrome (pSS), autoimmune thyroid disease (AITD) and psoriasis. This increased IL-21 even positively associates with Tfh cells, plasma cells, autoantibodies and disease activity in SLE and RA. Additionally, IL-21 has been utilized as a therapeutic target in SLE, RA, T1D and psoriatic mouse models. Profoundly, clinical trials have shown safety and improvement in RA patients. However, tolerance and long-term pharmacodynamics effects with low bioavailability have been found in SLE patients. Therefore, this review aims to summarize the latest progress on IL-21 function and its signaling pathway and discuss the role of IL-21 in the pathogenesis of and therapy for autoimmune diseases, with the hope of providing potential therapeutic and diagnostic strategies for clinical use.

Association between Interleukin-21 and Interleukin-21 receptor gene polymorphisms with susceptibility to chronic hepatitis B virus infection and HBV spontaneous clearance in Iranian population.

Hepatitis B virus (HBV) infection is a major public health concern due to the infection often leads to chronic infection, liver cirrhosis and also liver cancer. The host immune response to HBV infection and also genetic background play significant role in outcome of infection. Single nucleotide polymorphisms (SNPs) are the most important kind of variation in genetic sequences that caused by point mutations. As cytokines have major roles in viral infections, it seems that cytokine gene polymorphisms are independently associated with response to viral infections. Interleukin 21 (IL-21) plays an influential role in both innate and adaptive immune responses. Its specific receptor, IL-21R, produced and located on the surface of T, B and natural killer (NK) cells and is critical for the proliferation and differentiation of these immune effector cells. Many studies confirmed that the IL-21 involved in response to viral infections. We aimed to investigate the association of G/T IL-21 (rs2055979) and C/T IL-21R (rs3093390) gene polymorphisms with chronic hepatitis B virus infection and HBV spontaneous clearance in Iranian population. METHODS: In this study, blood samples were gathered from 320 patients with chronic HBV and 310 healthy controls and also 120 HBV spontaneous clearance individuals. Following genomic DNA extraction, genotypes of the selected SNPs determined by PCR and restriction fragment length polymorphism (RFLP) method. The results were analyzed by SPSS software using Chi-square, Logistic Regression, ANOVA and Independent Samples t-Test. RESULTS: According to our results, in IL-21R (rs3093390 C/T) gene polymorphism, allele frequency of T is statistically different in the HBV spontaneous clearance group compared to chronic HBV cases. But there is no significant difference between G/T IL-21 (rs2055979) and C/T IL-21R (rs3093390) genotypes distribution in three groups. Also we found that higher serum aspartate transaminase (AST) level in HBV spontaneous clearance group is significantly associated with TT genotype of IL-21 (rs2055979) compared to GG genotype (P value = 0.006). DISCUSSION: Our results showed that T allele frequency in IL-21R (rs3093390 C/T) gene polymorphism could consider as a host genetic factor for HBV spontaneous clearance. Probably we can serve it as a potential prognostic genetic marker for spontaneous clearance of HBV infection.

Defective IgA response to atypical intestinal commensals in IL-21 receptor deficiency reshapes immune cell homeostasis and mucosal immunity.

Despite studies indicating the effects of IL-21 signaling in intestinal inflammation, its roles in intestinal homeostasis and infection are not yet clear. Here, we report potent effects of commensal microbiota on the phenotypic manifestations of IL-21 receptor deficiency. IL-21 is produced highly in the small intestine and appears to be critical for mounting an IgA response against atypical commensals such as segmented filamentous bacteria and Helicobacter, but not to the majority of commensals. In the presence of these atypical commensals, IL-21R-deficient mice exhibit reduced numbers of germinal center and IgA+ B cells and expression of activation-induced cytidine deaminase in Peyer's patches as well as a significant decrease in small intestine IgA+ plasmablasts and plasma cells, leading to higher bacterial burdens and subsequent expansion of Th17 and Treg cells. These microbiota-mediated secondary changes in turn enhance T cell responses to an oral antigen and strikingly dampen Citrobacter rodentium-induced immunopathology, demonstrating a complex interplay between IL-21-mediated mucosal immunity, microbiota, and pathogens.

Nonredundant Roles of IL-21 and IL-4 in the Phased Initiation of Germinal Center B Cells and Subsequent Self-Renewal Transitions.

We examined the unique contributions of the cytokines IL-21 and IL-4 on germinal center (GC) B cell initiation and subsequent maturation in a murine model system. Similar to other reports, we found T follicular helper cell expression of IL-21 begins prior to T follicular helper cell migration into the B cell follicle and precedes that of IL-4. Consistent with this timing, IL-21 signaling has a greater influence on the perifollicular pre-GC B cell transition to the intrafollicular stage. Notably, Bcl6hi B cells can form in the combined absence of IL-21R- and STAT6-derived signals; however, these nascent GC B cells cease to proliferate and are more prone to apoptosis. When B cells lack either IL-21R or STAT6, aberrant GCs form atypical centroblasts and centrocytes that differ in their phenotypic maturation and costimulatory molecule expression. Thus, IL-4 and IL-21 play nonredundant roles in the phased progression of GC B cell development that can initiate in the combined absence of these cytokine signals.

Increased Binding of Specificity Protein 1 to the IL21R Promoter in B Cells Results in Enhanced B Cell Responses in Rheumatoid Arthritis.

B cells are implicated in rheumatoid arthritis (RA) based on the presence of autoantibodies and the therapeutic response to B cell depletion. IL-21 has a significant role in B cell development and function. Here we assess B cell responses to IL-21 and the mechanisms responsible for altered IL-21R expression in RA. Flow cytometry of PBMC and cultured B cells was used to quantify protein and mRNA levels of IL-21R, IL-21 signaling through pSTAT3, specificity protein 1 (SP1) and to determine cytokine production (IL-6) and maturation status of B cells in RA and healthy control subjects. SP1 binding to the IL21R promoter region in B cells was assessed with ChIP-qPCR. We demonstrate an increase in IL-21R expression in total and memory B cells from RA subjects, which correlated with responsiveness to IL-21 stimulation. Stimulation of naïve RA B cells with IL-21 and CD40L resulted in an increase in differentiation into plasmablasts and an increase in IL-6 production in comparison to healthy controls, which was dose dependent on IL-21 stimulation. IL-21R expression on memory B cells in RA synovial fluid was comparable to peripheral blood making our study pertinent to understanding B cell responses in the joint and site of inflammation. We identified an increase in SP1 protein and mRNA in RA B cells and demonstrate an increase in binding of SP1 to the IL21R promoter region, which suggests a mechanism by which IL-21R expression is enhanced on B cells in RA. Taken together, our results indicate a mechanism by which IL-21 enhances B cell development and function in RA through an SP1 mediated increase in IL-21R expression on B cells.

Oxymatrine exhibits anti-tumor activity in gastric cancer through inhibition of IL-21R-mediated JAK2/STAT3 pathway.

Oxymatrine (OMT) as a type of alkaloids collected from Sophora flavescens Ait exerts some biological functions including anticancer properties. Here, we investigated the therapeutic effects of OMT in gastric cancer cells (HGC 27 and AGS). As a result, the exposure of gastric cancer (GC) cells to OMT contributed to the suppression of cell proliferation and invasion. Interleukin 21 receptor (IL-21R) was identified to be differentially expressed between OMT treatment group (4 mg/mL) and control group (0 mg/mL), and knockdown of IL-21R repressed cell proliferation and invasion via inactivation of the JAK2/STAT3 pathway. The rescue experiment showed that IL-21R overexpression attenuated the anti-tumor effects of OMT through activation of the JAK2/STAT3 pathway. Moreover, the expression of IL-21R was significantly upregulated in GC samples compared with the adjacent normal tissues and associated with overall survival (OS) and tumor recurrence of GC patients. Taken together, in this study, we evaluated the anti-tumor effects of OMT on GC by investigating proliferation and invasion ability changes, and our findings show that OMT exhibits effects via regulation of JAK/STAT signaling pathway. Through the mechanism study, we may enlighten the potential therapeutic target for treatment of GC.