A polymorphism within IL21R confers risk for systemic lupus erythematosus

Genetic characteristics of common variable immunodeficiency patients with autoimmunity

Background: The pathogenesis of common variable immunodeficiency disorder (CVID) is complex, especially when combined with autoimmunity. Genetic factors may be potential explanations for this complex situation, and whole genome sequencing (WGS) provide the basis for this potential. Methods: Genetic information of patients with CVID with autoimmunity, together with their first-degree relatives, was collected through WGS. The association between genetic factors and clinical phenotypes was studied using genetic analysis strategies such as sporadic and pedigree. Results: We collected 42 blood samples for WGS (16 CVID patients and 26 first-degree relatives of healthy controls). Through pedigree, sporadic screening strategies and low-frequency deleterious screening of rare diseases, we obtained 9,148 mutation sites, including 8,171 single-nucleotide variants (SNVs) and 977 Insertion-deletions (InDels). Finally, we obtained a total of 28 candidate genes (32 loci), of which the most common mutant was LRBA. The most common autoimmunity in the 16 patients was systematic lupus erythematosis. Through KEGG pathway enrichment, we identified the top ten signaling pathways, including "primary immunodeficiency", "JAK-STAT signaling pathway", and "T-cell receptor signaling pathway". We used PyMOL to predict and analyse the three-dimensional protein structures of the NFKB1, RAG1, TIRAP, NCF2, and MYB genes. In addition, we constructed a PPI network by combining candidate mutants with genes associated with CVID in the OMIM database via the STRING database. Conclusion: The genetic background of CVID includes not only monogenic origins but also oligogenic effects. Our study showed that immunodeficiency and autoimmunity may overlap in genetic backgrounds. Clinical Trial Registration: identifier ChiCTR2100044035.

IL-21 (rs2055979 and rs2221903)/IL-21R (rs3093301) Polymorphism and High Levels of IL-21 Are Associated with Rheumatoid Arthritis in Mexican Patients

Rheumatoid Arthritis (RA) is characterized by joint destruction, chronic inflammation, and autoantibody production. IL-21/IL-21R plays an essential role in the immunopathology of RA. Elevated IL-21 serum levels have been associated with RA and disease activity. Here, we evaluated the association of IL-21/IL-21R polymorphisms and IL-21 serum levels with RA. The study included 275 RA patients and 280 Control subjects (CSs). Single nucleotide polymorphisms IL-21 (rs2055979 and rs2221903) and IL-21R (rs3093301) were genotyped using PCR-RFLP. Clinical activity was evaluated by DAS28-ESR; IL-21 and anti-CCP serum levels were quantified by ELISA. The IL-21 rs2055979 AA genotype was higher in RA patients than in the CS group (p = 0.0216, OR = 1.761, 95% CI = 1.085-2.859); furthermore, RA patients showed anti-CCP elevated levels compared to the CA genotype (p = 0.0296). The IL21R rs3093301 AA genotype was also higher in RA patients than in the CS group (p = 0.0122, OR = 1.965, 95% CI = 1.153-3.348). The AT haplotypes of IL-21 rs2055979 and rs2221903 were more frequent (49%) in the RA group (p = 0.006). IL-21 serum levels were significantly elevated in the RA group, but without an association with IL-21 polymorphisms. In conclusion, IL-21 rs2255979 and IL-21R rs3093301 are associated with a higher risk of RA, and could be a genetic marker. Moreover, the elevated IL-21 levels in RA suggest that IL-21/IL-21R could be a therapeutic target in RA.

IL-21 has a critical role in establishing germinal centers by amplifying early B cell proliferation

The proliferation and differentiation of antigen‐specific B cells, including the generation of germinal centers (GC), are prerequisites for long‐lasting, antibody‐mediated immune protection. Affinity for antigen determines B cell recruitment, proliferation, differentiation, and competitiveness in the response, largely through determining access to T cell help. However, how T cell‐derived signals contribute to these outcomes is incompletely understood. Here, we report how the signature cytokine of follicular helper T cells, IL‐21, acts as a key regulator of the initial B cell response by accelerating cell cycle progression and the rate of cycle entry, increasing their contribution to the ensuing GC. This effect occurs over a wide range of initial B cell receptor affinities and correlates with elevated AKT and S6 phosphorylation. Moreover, the resultant increased proliferation can explain the IL‐21‐mediated promotion of plasma cell differentiation. Collectively, our data establish that IL‐21 acts from the outset of a T cell‐dependent immune response to increase cell cycle progression and fuel cyclic re‐entry of B cells, thereby regulating the initial GC size and early plasma cell output.

T Cell Help in the Autoreactive Germinal Center

The germinal center serves as a site of B cell selection and affinity maturation, critical processes for productive adaptive immunity. In autoimmune disease tolerance is broken in the germinal center reaction, leading to production of autoreactive B cells that may propagate disease. Follicular T cells are crucial regulators of this process, providing signals necessary for B cell survival in the germinal center. Here we review the emerging roles of follicular T cells in the autoreactive germinal center. Recent advances in immunological techniques have allowed study of the gene expression profiles and repertoire of follicular T cells at unprecedented resolution. These studies provide insight into the potential role follicular T cells play in preventing or facilitating germinal center loss of tolerance. Improved understanding of the mechanisms of T cell help in autoreactive germinal centers provides novel therapeutic targets for diseases of germinal center dysfunction.

Machine learning reveals distinct gene signature profiles in lesional and nonlesional regions of inflammatory skin diseases

Analysis of gene expression from cutaneous lupus erythematosus, psoriasis, atopic dermatitis, and systemic sclerosis using gene set variation analysis (GSVA) revealed that lesional samples from each condition had unique features, but all four diseases displayed common enrichment in multiple inflammatory signatures. These findings were confirmed by both classification and regression tree analysis and machine learning (ML) models. Nonlesional samples from each disease also differed from normal samples and each other by ML. Notably, the features used in classification of nonlesional disease were more distinct than their lesional counterparts, and GSVA confirmed unique features of nonlesional disease. These data show that lesional and nonlesional skin samples from inflammatory skin diseases have unique profiles of gene expression abnormalities, especially in nonlesional skin, and suggest a model in which disease-specific abnormalities in "prelesional" skin may permit environmental stimuli to trigger inflammatory responses leading to both the unique and shared manifestations of each disease.

Identification and Contribution of Inflammation-Induced Novel MicroRNA in the Pathogenesis of Systemic Lupus Erythematosus

Recently microRNAs (miRNAs) have been recognized as powerful regulators of many genes and pathways involved in the pathogenesis of inflammatory diseases including Systemic Lupus Erythematosus (SLE). SLE is an autoimmune disease characterized by production of various autoantibodies, inflammatory immune cells, and dysregulation of epigenetic changes. Several candidate miRNAs regulating inflammation and autoimmunity in SLE are described. In this study, we found significant increases in the expression of miR21, miR25, and miR186 in peripheral blood mononuclear cells (PBMCs) of SLE patients compared to healthy controls. However, miR146a was significantly decreased in SLE patients compared to healthy controls and was negatively correlated with plasma estradiol levels and with SLE disease activity scores (SLEDAI). We also found that protein levels of IL-12 and IL-21 were significantly increased in SLE patients as compared to healthy controls. Further, our data shows that protein levels of IL-12 were positively correlated with miR21 expression and protein levels of IL-21 positively correlated with miR25 and miR186 expression in SLE patients. In addition, we found that levels of miR21, miR25, and miR186 positively correlated with SLEDAI and miR146a was negatively correlated in SLE patients. Thus, our data shows a dynamic interplay between disease pathogenesis and miRNA expression. This study has translational potential and may identify novel therapeutic targets in patients with SLE.

Interferon Genes Are Influenced by 17β-Estradiol in SLE

Recent evidence suggests the existence of a nexus between inflammatory pathways and the female sex hormone 17β-estradiol, resulting in increased interferon-stimulated genes (ISGs), autoantibodies, and dysregulation of immune cells in SLE. However, the molecular mechanisms and the effect of estradiol on candidate target genes and their pathways remains poorly understood. Our previous work suggests that female SLE patients have increased estradiol levels compared to healthy controls. In the present study, we explored the effects of 17β-estradiol treatment on expression of IFN (interferons)-stimulated genes and pro-inflammatory cytokines/chemokines. We found significantly increased (5-10-fold) expression of IFN-regulated genes in healthy females. Furthermore, we found significantly increased plasma levels of IL-6, IL-12, IL-17, IL-18, stem cell factor (SCF), and IL-21/IL-23 in SLE patients compared to healthy controls, and those levels positively correlated with the plasma levels of 17β-estradiol. In addition, levels of IL-21 positively correlated with the SLE disease activity index (SLEDAI) score of SLE patients. In vitro treatment of PBMCs from either SLE patients or healthy controls with 17β-estradiol at physiological concentration (~50 pg/ml) also significantly increased secretion of many pro-inflammatory cytokines and chemokines (IL-6, IL-12, IL-17, IL-8, IFN-γ; MIP1α, and MIP1β) in both groups. Further our data revealed that 17β-estradiol significantly increased the percentage of CD3⁺CD69⁺ and CD3⁺IFNγ⁺ T cells; whereas, simultaneous addition of 17β-estradiol and an ERα inhibitor prevented this effect. Collectively, our findings indicate that 17β-estradiol participates in the induction of pro-inflammatory cytokines and chemokines and further influences interferon genes and pathways.

Limited sensitivity and specificity of the ACR/EULAR-2019 classification criteria for SLE in JSLE?-observations from the UK JSLE Cohort Study

OBJECTIVES

This study aimed to test the performance of the new ACR and EULAR criteria, that include ANA positivity as entry criterion, in JSLE.

METHODS

Performance of the ACR/EULAR-2019 criteria were compared with Systemic Lupus International Collaborating Clinics (SLICC-2012), using data from children and young people (CYP) in the UK JSLE Cohort Study (n = 482), with the ACR-1997 criteria used as reference standard. An unselected cohort of CYP positive for ANA (n = 129) was used to calculate positive/negative predictive values of the criteria.

RESULTS

At both first and last visits, the number of patients fulfilling the different classification criteria varied significantly (P < 0.001). The sensitivity of the SLICC-2012 criteria was higher when compared with that of the ACR/EULAR-2019 criteria at first and last visits (98% vs 94% for first visit, and 98% vs 96% for last visit; P < 0.001), when all available CYP were considered. The ACR/EULAR-2019 criteria were more specific when compared with the SLICC-2012 criteria (77% vs 67% for first visit, and 81% vs 71% for last visit; P < 0.001). Significant differences between the classification criteria were mainly caused by the variation in ANA positivity across ages. In the unselected cohort of ANA-positive CYP, the ACR/EULAR-2019 criteria produced the highest false-positive classification (6/129, 5%).

CONCLUSION

In CYP, the ACR/EULAR-2019 criteria are not superior to those of the SLICC-2012 or ACR-1997 criteria. If classification criteria are designed to include CYP and adult populations, paediatric rheumatologists should be included in the consensus and evaluation process, as seemingly minor changes can significantly affect outcomes.

New developments implicating IL-21 in autoimmune disease

Elevated interleukin (IL)-21 is a common finding in the tissues and/or sera of patients with autoimmune disease. CD4 T cells are the primary producers of IL-21; often the IL-21 producing CD4 T cells will express molecules associated with follicular helper cells (T_FH). Recent work has shown that the CD4 T cell-derived IL-21 is able to promote effector functions and memory differentiation of CD8 T cells in chronic infections and cancer. Autoimmunity has similarities to chronic infections and cancer. However, CD4 T cell-derived IL-21:IL21R signaling in CD8 T cells has not been fully appreciated in the context of autoimmunity. In this review, we assess the current knowledge regarding CD4 T cell-derived IL-21 and IL21R signaling within CD8 T cells and evaluate what implications it has within several autoimmune diseases including systemic lupus erythematous, rheumatoid arthritis, juvenile idiopathic arthritis, type 1 diabetes mellitus, psoriasis, Sjögren's syndrome, vitiligo, antiphospholipid syndrome, pemphigus, and giant cell arteritis.

Understanding the genetics of systemic lupus erythematosus using Bayesian statistics and gene network analysis

The publication of genetic epidemiology meta-analyses has increased rapidly, but it has been suggested that many of the statistically significant results are false positive. In addition, most such meta-analyses have been redundant, duplicate, and erroneous, leading to research waste. In addition, since most claimed candidate gene associations were false-positives, correctly interpreting the published results is important. In this review, we emphasize the importance of interpreting the results of genetic epidemiology meta-analyses using Bayesian statistics and gene network analysis, which could be applied in other diseases.

CD52 Is Elevated on B cells of SLE Patients and Regulates B Cell Function

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by B cell dysregulation and breaks in tolerance that lead to the production of pathogenic autoantibodies. We performed single-cell RNA sequencing of B cells from healthy donors and individuals with SLE which revealed upregulated CD52 expression in SLE patients. We further demonstrate that SLE patients exhibit significantly increased levels of B cell surface CD52 expression and plasma soluble CD52, and levels of soluble CD52 positively correlate with measures of lupus disease activity. Using CD52-deficient JeKo-1 cells, we show that cells lacking surface CD52 expression are hyperresponsive to B cell receptor (BCR) signaling, suggesting an inhibitory role for the surface-bound protein. In healthy donor B cells, antigen-specific BCR-activation initiated CD52 cleavage in a phospholipase C dependent manner, significantly reducing cell surface levels. Experiments with recombinant CD52-Fc showed that soluble CD52 inhibits BCR signaling in a manner partially-dependent on Siglec-10. Moreover, incubation of unstimulated B cells with CD52-Fc resulted in the reduction of surface immunoglobulin and CXCR5. Prolonged incubation of B cells with CD52 resulted in the expansion of IgD+IgMlo anergic B cells. In summary, our findings suggest that CD52 functions as a homeostatic protein on B cells, by inhibiting responses to BCR signaling. Further, our data demonstrate that CD52 is cleaved from the B cell surface upon antigen engagement, and can suppress B cell function in an autocrine and paracrine manner. We propose that increased expression of CD52 by B cells in SLE represents a homeostatic mechanism to suppress B cell hyperactivity.

B Cell Aberrance in Lupus: the Ringleader and the Solution

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease with high heterogeneity but the common characterization of numerous autoantibodies and systemic inflammation which lead to the damage of multiple organs. Aberrance of B cells plays a pivotal role in the immunopathogenesis of SLE via both antibody-dependent and antibody-independent manners. Escape of autoreactive B cells from the central and peripheral tolerance checkpoints, over-activation of B cells and their excessive cytokines release which drive T cells and dendritic cells stimulation, and dysregulated surface molecules, as well as intracellular signal pathways involved in B cell biology, are all contributing to B cell aberrance and participating in the pathogenesis of SLE. Based on that rationale, targeting aberrance of B cells and relevant molecules and pathways is expected to be a promising strategy for lupus control. Multiple approaches targeting B cells through different mechanisms have been attempted, including B-cell depletion via monoclonal antibodies against B-cell-specific molecules, blockade of B-cell survival and activation factors, suppressing T-B crosstalk by interrupting costimulatory molecules and inhibiting intracellular activation signaling cascade by targeting pathway molecules in B cells. Though most attempts ended in failure, the efficacy of B-cell targeting has been encouraged by the FDA approval of belimumab that blocks B cell-activating factor (BAFF) and the recommended use of anti-CD20 as a remedial therapy in refractory lupus. Still, quantities of clinical trials targeting B cells or relevant molecules are ongoing and some of them have displayed promising preliminary results. Additionally, advances in multi-omics studies help deepen our understandings of B cell biology in lupus and may promote the discovery of novel potential therapeutic targets. The combination of real-world data with basic research achievements may pave the road to conquering lupus.

Regulatory T cells in inflammatory skin disease: from mice to humans

The skin is the largest organ in the body and one of the primary barriers to the environment. In order to optimally protect the host, the skin is home to numerous immune cell subsets that interact with each other and other non-immune cells to maintain organ integrity and function. Regulatory T cells (Tregs) are one of the largest immune cell subsets in skin. They play a critical role in regulating inflammation and facilitating organ repair. In doing so, they adopt unique and specialized tissue-specific functions. In this review, we compare and contrast the role of Tregs in cutaneous immune disorders from mice and humans, with a specific focus on scleroderma, alopecia areata, atopic dermatitis, cutaneous lupus erythematosus and psoriasis.

Dysregulation of T Follicular Helper Cells in Lupus

Although multiple and overlapping mechanisms are ultimately responsible for the immunopathology observed in patients with systemic lupus erythematosus, autoreactive Abs secreted by autoreactive plasma cells (PCs) are considered to play a critical role in disease progression and immunopathology. Given that PCs derive from the germinal centers (GC), long-term dysregulated GC reactions are often associated with the development of spontaneous autoantibody responses and immunopathology in systemic lupus erythematosus patients. In this review, we summarize the emerging evidence concerning the roles of T follicular helper cells in regulating pathogenic GC and autoreactive PC responses in lupus.

B Cell Abnormalities in Systemic Lupus Erythematosus and Lupus Nephritis-Role in Pathogenesis and Effect of Immunosuppressive Treatments

Abnormalities in B cells play pivotal roles in the pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis (LN). Breach in central and peripheral tolerance mechanisms generates autoreactive B cells which contribute to the pathogenesis of SLE and LN. Dysregulation of B cell transcription factors, cytokines and B cell-T cell interaction can result in aberrant B cell maturation and autoantibody production. These immunological abnormalities also lead to perturbations in circulating and infiltrating B cells in SLE and LN patients. Conventional and novel immunosuppressive medications confer differential effects on B cells which have important clinical implications. While cyclophosphamide and mycophenolate mofetil (MMF) showed comparable clinical efficacy in active LN, MMF induction was associated with earlier reduction in circulating plasmablasts and plasma cells. Accumulating evidence suggests that MMF maintenance is associated with lower risk of disease relapse than azathioprine, which may be explained by its more potent and selective suppression of B cell proliferation. Novel therapeutic approaches targeting the B cell repertoire include B cell depletion with monoclonal antibodies binding to cell surface markers, inhibition of B cell cytokines, and modulation of costimulatory signals in B cell-T cell interaction. These biologics, despite showing improvements in serological parameters and proteinuria, did not achieve primary endpoints when used as add-on therapy to standard treatments in active LN patients. Other emerging treatments such as calcineurin inhibitors, mammalian target of rapamycin inhibitors and proteasome inhibitors also show distinct inhibitory effects on the B cell repertoire. Advancement in the knowledge on B cell biology has fueled the development of new therapeutic strategies in SLE and LN. Modification in background treatments, study endpoints and selective recruitment of subjects showing aberrant B cells or its signaling pathways when designing future clinical trials may better elucidate the roles of these novel therapies for SLE and LN patients.

Paradoxical role of Breg-inducing cytokines in autoimmune diseases

Regulatory B cells (Breg) are crucial immunoregulators that maintain peripheral tolerance and suppress inflammatory autoimmune responses. In recent years, our understanding on the nature and mechanism of action of Bregs has revealed the important role of cytokines in promoting the regulatory properties of this unique B cell subset, both in animal and human models. In this review, we compiled the cytokines that have been reported by multiple studies to induce the expansion of Breg. The Breg-inducing cytokines which are currently known include IL-21, IL-6, IL1β, IFNα, IL-33, IL-35, BAFF and APRIL. As cytokines are also known to play a pivotal role in the pathogenesis of autoimmune diseases, in parallel we reviewed the pattern of expression of the Breg-inducing cytokines in Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA), Inflammatory Bowel Diseases (IBD) and Multiple Sclerosis (MS). We show here that Breg-inducing cytokines are commonly implicated in these inflammatory diseases where they typically have a higher expression than in healthy individuals, suggesting their paradoxical nature. Interestingly, despite the general overexpression of Breg-inducing cytokines, it is known that Breg cells are often numerically or functionally impaired in various autoimmune conditions. Considering these alterations, we explored the possible parameters that may influence the function of Breg-inducing cytokines in exhibiting either their regulatory or pro-inflammatory properties in the context of autoimmune conditions.

Integrated analysis of lncRNA, miRNA and mRNA expression profiling in patients with systemic lupus erythematosus

INTRODUCTION

A great deal of research has reported dysregulated expression of genes in systemic lupus erythematosus (SLE). This study aimed to analyze the lncRNA, miRNA and mRNA expression profile in SLE.

MATERIAL AND METHODS

RNA sequencing (RNA-seq) was used to detect the dysregulated RNAs in SLE. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis were used to explore the function of these differentially expressed RNAs.

RESULTS

2,353 lncRNAs, 827 mRNAs and 24 miRNAs were shown to be differentially expressed. GO analyses demonstrated that differentially expressed RNAs were enriched in a variety of molecular functions and biological processes including ribonucleotide, protein serine/threonine kinase activity function, regulation of B cell differentiation and others. KEGG pathway analyses revealed that differentially expressed mRNAs and lncRNAs were both enriched in FcγR-mediated phagocytosis, glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate and glyoxylate and dicarboxylate metabolism pathways. The up-regulated miRNAs target genes were mainly enriched in the nuclear factor-κB (NF-κB) signaling pathway. The down-regulated miRNAs target genes were significantly enriched in metabolism of xenobiotics by cytochrome P450, bile secretion and terpenoid backbone biosynthesis pathways.

CONCLUSIONS

The current study reveals a comprehensive expression profile of lncRNAs, miRNAs and mRNAs and implies potential regulatory functions of these RNAs which are involved in the pathogenesis of SLE.

Unique Phenotypes and Functions of Follicular Helper T Cells and Regulatory T Cells in Sjögren's Syndrome

Sjogren’s syndrome (SS) is a T cell-mediated autoimmune disease of the systemic exocrine glands, such as salivary and lacrimal glands. A variety of T-cell subpopulations maintain immune tolerance in the thymus and periphery through complex immune responses including cellular and humoral immunity. The T-cell subpopulations exhibiting abnormal or unique phenotypes and impaired functionality have been reported to play important roles in the cellular mechanisms of autoimmunity in SS patients and animal models of SS. In this review, we focused on follicular helper T cells related to antibody production and regulatory T cells to control immune tolerance in the pathogenesis of SS. The unique roles of these T-cell subpopulations in the process of the onset or development of SS have been demonstrated in this review of recent publications. The clinical application of these T-cell subpopulations will be helpful for the development of new techniques for diagnosis or treatment of SS in the future.

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.

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.

The Common Cytokine Receptor γ Chain Family of Cytokines

Interleukin (IL)-2, IL-4, IL-7, IL-9, IL-15, and IL-21 form a family of cytokines based on their sharing the common cytokine receptor γ chain (γc), which was originally discovered as the third receptor component of the IL-2 receptor, IL-2Rγ. The IL2RG gene is located on the X chromosome and is mutated in humans with X-linked severe combined immunodeficiency (XSCID). The breadth of the defects in XSCID could not be explained solely by defects in IL-2 signaling, and it is now clear that γc is a shared receptor component of the six cytokines noted above, making XSCID a disease of defective cytokine signaling. Janus kinase (JAK)3 associates with γc, and JAK3-deficient SCID phenocopies XSCID, findings that served to stimulate the development of JAK3 inhibitors as immunosuppressants. γc family cytokines collectively control broad aspects of lymphocyte development, growth, differentiation, and survival, and these cytokines are clinically important, related to allergic and autoimmune diseases and cancer as well as immunodeficiency. In this review, we discuss the actions of these cytokines, their critical biological roles and signaling pathways, focusing mainly on JAK/STAT (signal transducers and activators of transcription) signaling, and how this information is now being used in clinical therapeutic efforts.

Act1 is a negative regulator in T and B cells via direct inhibition of STAT3

Although Act1 (adaptor for IL-17 receptors) is necessary for IL-17-mediated inflammatory responses, Act1- (but not Il17ra-, Il17rc-, or Il17rb-) deficient mice develop spontaneous SLE- and Sjögren's-like diseases. Here, we show that Act1 functions as a negative regulator in T and B cells via direct inhibition of STAT3. Mass spectrometry analysis detected an Act1-STAT3 complex, deficiency of Act1 (but not Il17ra-, Il17rc-, or Il17rb) results in hyper IL-23- and IL-21-induced STAT3 activation in T and B cells, respectively. IL-23R deletion or blockade of IL-21 ameliorates SLE- and Sjögren's-like diseases in Act1-/- mice. Act1 deficiency results in hyperactivated follicular Th17 cells with elevated IL-21 expression, which promotes T-B cell interaction for B cell expansion and antibody production. Moreover, anti-IL-21 ameliorates the SLE- and Sjögren's-like diseases in Act1-deficient mice. Thus, IL-21 blocking antibody might be an effective therapy for treating SLE- and Sjögren's-like syndrome in patients containing Act1 mutation.

IL-21 drives expansion and plasma cell differentiation of autoreactive CD11chiT-bet+ B cells in SLE

Although the aetiology of systemic lupus erythematosus (SLE) is unclear, dysregulated B cell responses have been implicated. Here we show that an unusual CD11c^hiT-bet⁺ B cell subset, with a unique expression profile including chemokine receptors consistent with migration to target tissues, is expanded in SLE patients, present in nephrotic kidney, enriched for autoreactive specificities and correlates with defined clinical manifestations. IL-21 can potently induce CD11c^hiT-bet⁺ B cells and promote the differentiation of these cells into Ig-secreting autoreactive plasma cells. While murine studies have identified a role for T-bet-expressing B cells in autoimmunity, this study describes and exemplifies the importance of CD11c^hiT-bet⁺ B cells in human SLE.

Systemic lupus erythematosus (SLE) is associated with altered B cell responses but the underlying aetiology is still unclear. Here the authors show that a CD11c^hiT-bet⁺ B cell subset with a unique phenotype and transcriptome is increased in patients with SLE, can be expanded by IL-21, and may contribute to autoimmune responses in SLE.

Spontaneous germinal centers and autoimmunity

Germinal centers (GCs) are dynamic microenvironments that form in the secondary lymphoid organs and generate somatically mutated high-affinity antibodies necessary to establish an effective humoral immune response. Tight regulation of GC responses is critical for maintaining self-tolerance. GCs can arise in the absence of purposeful immunization or overt infection (called spontaneous GCs, Spt-GCs). In autoimmune-prone mice and patients with autoimmune disease, aberrant regulation of Spt-GCs is thought to promote the development of somatically mutated pathogenic autoantibodies and the subsequent development of autoimmunity. The mechanisms that control the formation of Spt-GCs and promote systemic autoimmune diseases remain an open question and the focus of ongoing studies. Here, we discuss the most current studies on the role of Spt-GCs in autoimmunity.

Pathogenic mechanisms of IgE-mediated inflammation in self-destructive autoimmune responses

Autoantibodies of the IgG subclass are pathogenic in a number of autoimmune disorders such as systemic lupus erythomatosus. The presence of circulating IgE autoantibodies in autoimmune patients has also been known for almost 40 years. Despite their role in allergies, IgE autoantibodies are not associated with a higher rate of atopy in these patients. However, recently they have been recognized as active drivers of autoimmunity through mechanisms involving the secretion of Type I interferons by plasmacytoid dendritic cells (pDC), the recruitment of basophils to lymph nodes, and the activation of adaptive immune responses through B and T cells. Here, we will review the formation, prevalence, affinity, and roles of the IgE autoantibodies that have been described in autoimmunity. We also present novel evidence supporting that triggering of IgE receptors in pDC induces LC3-associated phagocytosis, a cellular process also known as LAP that is associated with interferon responses. The activation of pDC with immune complexes formed by DNA-specific IgE antibodies also induce potent B-cell differentiation and plasma cell formation, which further define IgE's role in autoimmune humoral responses.

T follicular helper cells, interleukin-21 and systemic lupus erythematosus

SLE is a chronic systemic autoimmune disease characterized by a breakdown of tolerance to nuclear antigens and generation of high-affinity pathogenic autoantibodies. These autoantibodies form, with autoantigens, immune complexes that are involved in organ and tissue damages. Understanding how the production of these pathogenic autoantibodies arises is of prime importance. T follicular helper cells (Tfh) and IL-21 have emerged as central players in this process. This article reviews the pathogenic role of Tfh cells and IL-21 in SLE.

Interleukin-21 rs2055979 and Interleukin-21 receptor rs3093390 genetic variants and hepatitis C virus chronic infection

AIM

The aim of this case-control study was to investigate association of G/T IL-21 (rs2055979) and C/T IL-21R (rs3093390) gene polymorphisms with chronic hepatitis C virus in Iranian Patients.

BACKGROUND

Interleukin 21 (IL-21) has a significant function in the regulation of cellular immune responses. Its exclusive receptor, IL-21R, expressed on the surface of T, B and NK cells and is important for the proliferation and differentiation of these immune cells. Hence, it was suggested to be involved in response to viral infections.

METHODS

This study follows a case-control study design and blood samples were collected from 290 patients with chronic HCV and 290 controls for both genes. Genomic DNA was extracted and then for each position, SNP was genotyped by the dedicated PCR and restriction fragment length polymorphism (RFLP) method. The results were analyzed by SPSS software using logistic regression and Chi-square tests.

RESULTS

Genotype frequencies of GG, GT and TT in IL21 gene (rs3093390) were found to be 27.6%, 48.3%, 24.1% and 25.2%, 55,5%, 19,3% respectively in HCV infected patients and control group. For IL21R gene (rs2055979) genotype frequencies of CC, CT and TT were 63.8%, 31.4%, 4.8% and 61.4%, 29.7%, 9.0% respectively in HCV infected patients and control group. P values for genotype and allele frequencies were p=0.188, p=0.769 for IL21 gene, and p=0.144, p=0.179 for IL21R gene respectively.

CONCLUSION

As a result, there is no evidence for an association between IL-21 (rs2055979) and IL-21R (rs3093390) gene polymorphisms with chronic hepatitis C virus in Iranian Patients.

Follicular Helper T Cells in Systemic Lupus Erythematosus: Why Should They Be Considered as Interesting Therapeutic Targets?

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by B cell hyperactivity leading to the production of autoantibodies, some of which having a deleterious effect. Reducing autoantibody production thus represents a way of controlling lupus pathogenesis, and a better understanding of the molecular and cellular factors involved in the differentiation of B cells into plasma cells could allow identifying new therapeutic targets. Follicular helper T cells (T_FH) represent a distinct subset of CD4⁺ T cells specialized in providing help to B cells. They are required for the formation of germinal centers and the generation of long-lived serological memory and, as such, are suspected to play a central role in SLE. Recent advances in the field of T_FH biology have allowed the identification of important molecular factors involved in T_FH differentiation, regulation, and function. Interestingly, some of these T_FH-related molecules have been described to be dysregulated in lupus patients. In the present review, we give an overview of the aberrant expression and/or function of such key players in lupus, and we highlight their potential as therapeutic targets.

Several Critical Cell Types, Tissues, and Pathways Are Implicated in Genome-Wide Association Studies for Systemic Lupus Erythematosus

We aimed to elucidate the cell types, tissues, and pathways influenced by common variants in systemic lupus erythematosus (SLE). We applied a nonparameter enrichment statistical approach, termed SNPsea, in 181 single nucleotide polymorphisms (SNPs) that have been identified to be associated with the risk of SLE through genome-wide association studies (GWAS) in Eastern Asian and Caucasian populations, to manipulate the critical cell types, tissues, and pathways. In the two most significant cells’ findings (B lymphocytes and CD14+ monocytes), we subjected the GWAS association evidence in the Han Chinese population to an enrichment test of expression quantitative trait locus (QTL) sites and DNase I hypersensitivity, respectively. In both Eastern Asian and Caucasian populations, we observed that the expression level of SLE GWAS implicated genes was significantly elevated in xeroderma pigentosum B cells (P ≤ 1.00 × 10⁻⁶), CD14+ monocytes (P ≤ 2.74 × 10⁻⁴) and CD19+ B cells (P ≤ 2.00 × 10⁻⁶), and plasmacytoid dendritic cells (pDCs) (P ≤ 9.00 × 10⁻⁶). We revealed that the SLE GWAS-associated variants were more likely to reside in expression QTL in B lymphocytes (q₁/q₀ = 2.15, P = 1.23 × 10⁻⁴⁴) and DNase I hypersensitivity sites (DHSs) in CD14+ monocytes (q₁/q₀ = 1.41, P = 0.08). We observed the common variants affected the risk of SLE mostly through by regulating multiple immune system processes and immune response signaling. This study sheds light on several immune cells and responses, as well as the regulatory effect of common variants in the pathogenesis of SLE.

Impact of the polymorphism in vitamin D receptor gene BsmI and the risk of systemic lupus erythematosus: an updated meta-analysis

The etiology of system lupus erythematosus (SLE) still remains unclear, and vitamin D is associated with immune response. Although a few studies are conducted to investigate the association between polymorphism in vitamin D receptor (VDR) genes and SLE risk, their results are conflicting. Following the guideline of PRISMA, we conducted a systematic search and meta-analysis of the BsmI polymorphism rs1544410 and the risk of SLE. The pooled odds ratios (OR) and its 95 % confidential interval (CI) were calculated by using Stata Version 10 with dominant and recessive model and allele analyses. Nine studies were included in our meta-analysis with a total of 1247 SLE cases and 1687 controls. No significant association was found in both models in the overall population. Only Bb + BB genotypes showed a significantly elevated SLE risk in Asian subgroup with an OR of 3.26 (95 % CI = 1.30-8.17) while no significance was observed in Caucasian population. Notably, B allele significantly increased the SLE risk among Asian population with an OR of 2.29 (95 % CI = 1.14-4.61). No positive findings were reported in Caucasian population and in the overall analysis. In Asian population, Bb + BB genotype and B allele can significantly increase the SLE risk.

Genetics and novel aspects of therapies in systemic lupus erythematosus

Autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis, autoimmune hepatitis and inflammatory bowel disease, have complex pathogeneses and the factors which cause these disorders are not well understood. But all have in common that they arise from a dysfunction of the immune system, interpreting self components as foreign antigens. Systemic lupus erythematosus (SLE) is one of these complex inflammatory disorders that mainly affects women and can lead to inflammation and severe damage of virtually any tissue and organ. Recently, the application of advanced techniques of genome-wide scanning revealed more genetic information about SLE than previously possible. These case-control or family-based studies have provided evidence that SLE susceptibility is based (with a few exceptions) on an individual accumulation of various risk alleles triggered by environmental factors and also help to explain the discrepancies in SLE susceptibility between different populations or ethnicities. Moreover, during the past years new therapies (autologous stem cell transplantation, B cell depletion) and improved conventional treatment options (corticosteroids, traditional and new immune-suppressants like mycophenolate mofetile) changed the perspective in SLE therapeutic approaches. Thus, this article reviews genetic aspects of this autoimmune disease, summarizes clinical aspects of SLE and provides a general overview of conventional and new therapeutic approaches in SLE.

Pouring fuel on the fire: Th17 cells, the environment, and autoimmunity

Cytokines play a critical role in controlling the differentiation of CD4 Th cells into distinct subsets, including IL-17-producing Th17 cells. Unfortunately, the incidence of a number of autoimmune diseases, particularly those in which the IL-23/IL-17 axis has been implicated, has risen in the last several decades, suggesting that environmental factors can promote autoimmunity. Here we review the role of cytokines in Th17 differentiation, particularly the role of IL-23 in promoting the differentiation of a pathogenic subset of Th17 cells that potently induce autoimmune tissue inflammation. Moreover, we highlight emerging data that indicate that environmental factors, including the intestinal microbiota and changes in diet, can alter normal cytokine regulation with potent effects on Th17 differentiation and thus promote autoimmunity, which has strong implications for human disease.

Advances in IL-21 biology - enhancing our understanding of human disease

Cytokines play critical roles in regulating the development and function of immune cells. Cytokines function by binding specific multimeric receptor complexes and activating intracellular signaling pathways that often involve JAKs and STATs. In addition to contributing to immunity, when production of cytokines is perturbed, they can contribute to disease. IL-21 is a pleiotropic cytokine produced predominantly by CD4(+) T cells and NKT cells. Gene-targeting studies in mice and in vitro analyses of human and murine lymphocytes have revealed central roles of IL-21 in regulating effector functions of T cells, NK cells and B cells. However, recent discoveries of loss-of function mutations in IL21 or IL21R in humans have unveiled unexpected roles for IL-21 in immune regulation. This review will focus on recent advances in IL-21 biology that have highlighted its critical role in normal immunity and how dysregulated IL-21 production can lead to immunodeficiency and autoimmune conditions.

IL-21 acts as a promising therapeutic target in systemic lupus erythematosus by regulating plasma cell differentiation

Plasma cells, which secrete auto-antibodies, are considered to be the arch-criminal of autoimmune diseases such as systemic lupus erythematosus, but there are many cytokines involved in inducing the differentiation of B-cell subsets into plasma cells. Here, we emphasize IL-21, which has emerged as the most potent inducer of plasma cell differentiation. In this review, we focused on the promoting effects of IL-21 on plasma cell differentiation and discuss how these effects contribute to B cell-mediated autoimmune disease.

Evaluation of SLE Susceptibility Genes in Malaysians

Systemic Lupus Erythematosus (SLE) is a clinically heterogeneous autoimmune disease with strong genetic and environmental components. Our objective was to replicate 25 recently identified SLE susceptibility genes in two distinct populations (Chinese (CH) and Malays (MA)) from Malaysia. We genotyped 347 SLE cases and 356 controls (CH and MA) using the ImmunoChip array and performed an admixture corrected case-control association analysis. Associated genes were grouped into five immune-related pathways. While CH were largely homogenous, MA had three ancestry components (average 82.3% Asian, 14.5% European, and 3.2% African). Ancestry proportions were significantly different between cases and controls in MA. We identified 22 genes with at least one associated SNP (P < 0.05). The strongest signal was at HLA-DRA (P_Meta = 9.96 × 10⁻⁹; P_CH = 6.57 × 10⁻⁸, P_MA = 6.73 × 10⁻³); the strongest non-HLA signal occurred at STAT4 (P_Meta = 1.67 × 10⁻⁷; P_CH = 2.88 × 10⁻⁶, P_MA = 2.99 × 10⁻³). Most of these genes were associated with B- and T-cell function and signaling pathways. Our exploratory study using high-density fine-mapping suggests that most of the established SLE genes are also associated in the major ethnicities of Malaysia. However, these novel SNPs showed stronger association in these Asian populations than with the SNPs reported in previous studies.

Cytokine-Mediated Regulation of Plasma Cell Generation: IL-21 Takes Center Stage

During our life, we are surrounded by continuous threats from a diverse range of invading pathogens. Our immune system has evolved multiple mechanisms to efficiently deal with these threats so as to prevent them from causing disease. Terminal differentiation of mature B cells into plasma cells (PC) – the antibody (Ab) secreting cells of the immune system – is critical for the generation of protective and long-lived humoral immune responses. Indeed, efficient production of antigen (Ag)-specific Ab by activated B cells underlies the success of most currently available vaccines. The mature B-cell pool is composed of several subsets, distinguished from one according to size, surface marker expression, location, and Ag exposure, and they all have the capacity to differentiate into PCs. For a B-cell to acquire the capacity to produce Abs, it must undergo an extensive differentiation process driven by changes in gene expression. Two broad categories of Ags exist that cause B-cell activation and differentiation: T cell dependent (TD) or T cell independent (TI). In addition to the B-cell subset and nature of the Ag, it is important to consider the cytokine environment that can also influence how B-cell differentiation is achieved. Thus, while many cytokines can induce Ab-secretion by B cells after activation with mimics of TD and TI stimuli in vitro, they can have different efficacies and specificities, and can often preferentially induce production of one particular Ig isotype over another. Here, we will provide an overview of in vitro studies (mouse and human origin) that evaluated the role of different cytokines in inducing the differentiation of distinct B-cell subsets to the PC lineage. We will place particular emphasis on IL-21, which has emerged as the most potent inducer of terminal B-cell differentiation in humans. We will also focus on the role of IL-21 and defects in B-cell function and how these contribute to human immunopathologies such as primary immunodeficiencies and B-cell mediated autoimmune conditions.

Genetic association of IL-21 polymorphisms with dilated cardiomyopathy in a Han Chinese population

BACKGROUND

Autoimmune abnormalities appear to be major predisposing factors for dilated cardiomyopathy (DCM). Interleukin-21 (IL-21) gene polymorphisms have been previously found to be associated with autoimmune diseases. This study aimed to assess the role of IL-21 in DCM in a Han Chinese population.

PATIENTS AND METHODS

A total of 364 independent DCM patients and 384 unrelated healthy controls were recruited for this case-control association study. rs2055979 and rs12508721 were genotyped by PCR-RFLP. IL-21 plasma levels in samples from DCM and control individuals were evaluated by ELISA. The association between the SNPs and overall survival (OS) was evaluated by Kaplan-Meier analysis. Hazard ratios and 95 % confidence intervals (CIs) were assessed in a Cox regression analysis with adjustment for sex and age.

RESULTS

The T allele frequencies of both SNPs were higher in DCM patients than in controls (p < 0.001). The genotypic frequencies of rs2055979 G > T and rs12508721 C > T were associated with DCM in the codominant, dominant, and recessive models (p < 0.05). IL-21 plasma levels in patients were higher than those of the control subjects (p = 0.009). The TT genotypes of both SNPs were associated with significantly higher plasma levels (prs2055979 = 0.03, prs12508721 < 0.001). Kaplan-Meier analysis showed that the genotypic frequencies of both SNPs were associated with OS in the dominant and the recessive models (p < 0.001). The TT genotypes of both SNPs were associated with the worst OS (p < 0.001).

CONCLUSION

Our findings suggest that theIL-21 gene plays an important role in susceptibility to DCM as well as in the clinical outcome of this ailment in the Han Chinese population.

Differentiation of follicular helper T cells by salivary gland epithelial cells in primary Sjögren's syndrome

Follicular helper T cells (Tfh), which play a pivotal role in B cell activation and differentiation in lymphoid structures, secrete IL-21 whose augmented secretion is a hallmark of several autoimmune diseases. To decipher the cellular and molecular interactions occurring in salivary glands of patients suffering from primary Sjögren's syndrome (pSS), we investigated whether salivary gland epithelial cells (SGECs) were capable to induce Tfh differentiation. Co-cultures of naïve CD4(+) T cells and SGECs from both patients with pSS and controls were performed. Here, we report that IL-6 and ICOSL expression by SGECs contributes to naïve CD4(+) T differentiation into Tfh cells, as evidenced by their acquisition of a specific phenotype, characterized by Bcl-6, ICOS and CXCR5 expression and IL-21 secretion, but also but by their main functional feature: the capacity to enhance B lymphocytes survival. We demonstrated an increase of serum IL-21 with systemic activity. Finally, we analyzed the potential occurrence of a genetic association between IL-21 or IL-21R gene polymorphisms and pSS or elevated IL-21 secretion. This study, which demonstrates a direct induction of Tfh differentiation by SGECs, emphasizes a yet unknown pathogenic role of SGECs and suggests that Tfh and IL-21 might be relevant biomarkers and/or therapeutic targets in primary Sjögren's syndrome.

Contributions of B cells to lupus pathogenesis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies. This review summarizes first the results obtained in the mouse that have revealed how B cell tolerance is breached in SLE. We then review the B cell subsets, in addition to the autoAb producing cells, which contribute to SLE pathogenesis, focusing on marginal zone B cells, B-1 cells and regulatory B cells. Finally, we review the interactions between B cells and other immune cells that have been implicated in SLE, such as dendritic cells, macrophages, neutrophils and T cells.

Systemic lupus erythematosus diagnostics in the 'omics' era

Systemic lupus erythematosus is a complex autoimmune disease affecting multiple organ systems. Currently, diagnosis relies upon meeting at least four out of eleven criteria outlined by the ACR. The scientific community actively pursues discovery of novel diagnostics in the hope of better identifying susceptible individuals in early stages of disease. Comprehensive studies have been conducted at multiple biological levels including: DNA (or genomics), mRNA (or transcriptomics), protein (or proteomics) and metabolites (or metabolomics). The 'omics' platforms allow us to re-examine systemic lupus erythematosus at a greater degree of molecular resolution. More importantly, one is hopeful that these 'omics' platforms may yield newer biomarkers for systemic lupus erythematosus that can help clinicians track the disease course with greater sensitivity and specificity.