B cells participate in tolerance and autoimmunity through cytokine production

Comprehensive insights into rheumatoid arthritis: Pathophysiology, current therapies and herbal alternatives for effective disease management

Rheumatoid arthritis is a chronic autoimmune inflammatory disease characterized by immune response overexpression, causing pain and swelling in the synovial joints. This condition is caused by auto-reactive antibodies that attack self-antigens due to their incapacity to distinguish between self and foreign molecules. Dysregulated activity within numerous signalling and immunological pathways supports the disease's development and progression, elevating its complexity. While current treatments provide some alleviation, their effectiveness is accompanied by a variety of adverse effects that are inherent in conventional medications. As a result, there is a deep-rooted necessity to investigate alternate therapeutic strategies capable of neutralizing these disadvantages. Medicinal herbs display a variety of potent bioactive phytochemicals that are effective in the complementary management of disease, thus generating an enormous potency for the researchers to delve deep into the development of novel phytomedicine against autoimmune diseases, although additional evidence and understanding are required in terms of their efficacy and pharmacodynamic mechanisms. This literature-based review highlights the dysregulation of immune tolerance in rheumatoid arthritis, analyses the pathophysiology, elucidates relevant signalling pathways involved, evaluates present and future therapy options and underscores the therapeutic attributes of a diverse array of medicinal herbs in addressing this severe disease.

A Comprehensive Review on the Role of Interleukin-40 as a Biomarker for Diagnosing Inflammatory Diseases

Interleukins are a group of proteins that have a wide range of complex functions and are believed to be involved in several diseases and conditions. In particular, interleukin-40 (IL-40) is a recently identified cytokine associated with B cells that was first introduced by Catalan et al. in 2017. This cytokine has several roles in the body, including functioning in the formation of B cells in the bone marrow, IgA production, and expression in the intestinal microbiome. Moreover, IL-40 appears to be involved in numerous autoimmune and inflammatory conditions, such as rheumatoid arthritis, systemic lupus erythematosus, primary Sjogren's syndrome, ankylosing spondylitis, type 2 diabetes, Graves' disease, and hepatic cell carcinoma. Our understanding of this molecule is quite restricted due to its novelty. However, because of its inflammatory characteristics, there is a high probability that it contributes to a variety of inflammatory disease complications. The aim of the present review is to highlight all available data on the importance of assessing IL-40 levels in human diseases up to now, which could be used as a diagnostic biomarker for the onset or progression of numerous inflammatory diseases.

Identification of novel first-trimester serum biomarkers for early prediction of preeclampsia

BACKGROUND

Preeclampsia (PE) is a leading cause of maternal and perinatal mortality and morbidity worldwide, but effective early prediction remains a challenge due to the lack of reliable biomarkers.

METHODS

Based on the extensive human biobank of our large-scale assisted reproductive cohort platform, the first-trimester serum levels of 48 cytokines, total immunoglobulins (Igs), anti-phosphatidylserine (aPS) antibodies, and several previously reported PE biomarkers [including placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and activin A] were measured in 34 women diagnosed with PE and 34 matched normotensive controls.

RESULTS

The PE group has significantly higher first-trimester serum levels of interleukin (IL)-2Rα, IL-9, tumor necrosis factor-β (TNF-β), RANTES, hepatocyte growth factor (HGF), total IgM, and total IgG, and aPS IgG optical density (OD) value, as well as lower first-trimester serum levels of PlGF and total IgA and aPS-IgG immune complexes (IC) OD value than the control group. Combining top five first-trimester serum biomarkers (total IgM, total IgG, PlGF, aPS IgG, and total IgA) achieved superior predictive value [area under the curve (AUC) and 95% confidence interval (CI) 0.983 (0.952-1.000), with a sensitivity of 100% and a specificity of 94.1%] for PE development compared to PlGF and PlGF/sFlt-1 independently [AUC and 95% CI 0.825 (0.726-0.924) and 0.670 (0.539-0.800), respectively].

CONCLUSION

We identified novel first-trimester serum biomarkers and developed an effective first-trimester prediction model using immune-related factors and PlGF for PE, which could facilitate the development of early diagnostic strategies and provide immunological insight into the further mechanistic exploration of PE.

Co-Infection Talaromyces marneffei and Pneumocystis jirovecii in a Patient with Systemic Lupus Erythematosus

Talaromyces marneffei (TM) and Pneumocystis jirovecii (PJ) infection are opportunistic infections that typically affect individuals with compromised immune systems, such as those with HIV or immunodeficiency. However, these infections are rarely seen in patients with systemic lupus erythematosus (SLE). We present a case study of a 52-year-old woman diagnosed with SLE who developed a co-infection of TM and PJ after receiving glucocorticoids, mycophenolate mofetil (MMF), and belimumab therapy. The patient's pneumonia improved following treatment with voriconazole, clarithromycin, and compound sulfamethoxazole. This case highlights the potential risk of serious opportunistic infections in SLE patients receiving a combination of glucocorticoids, MMF, and belimumab. Close monitoring of lymphocyte count, immunoglobulin levels, and chest computed tomography scans can aid in the early detection of infections. To the best of our knowledge, this is the first reported case of TM and PJ co-infection in an SLE patient.

Early Cytomegalovirus Reactivation in Renal Recipients Is Associated with High Levels of B Cell Maturation Antigen Transcript Expression Prior to Transplantation

Cytomegalovirus (CMV) infection is the most frequent infection episode in kidney transplant (KT) recipients. Reactivation usually occurs in the first three months after transplantation and is associated with higher cellular and/or antibody-mediated rejection rates and poorer graft performance. CMV induces the expression of BAFF (B-cell-activating factor, a cytokine involved in the homeostasis of B cells), which communicates signals for survival and growth to B cells and virus-specific plasma cells via the R-BAFF (BAFF receptor), TACI (the calcium modulator, the cyclophilin ligand interactor), and BCMA (B cell maturation antigen) receptors. These molecules of the BAFF system have also been suggested as biomarkers for the development of alloantibodies and graft dysfunction. This prospective study included 30 CMV-IgG seropositive KT recipients. The expression levels of the genes BAFF-R, transmembrane activator and CAML interactor (TACI), and B cell maturation antigen (BCMA) in peripheral blood leukocytes (PBL) pre-KT were determined using qPCR. qPCR was also used to monitor CMV reactivation in the first three months following KT. The remainder of the KT recipients were classified as CMV- reactivation, and those with more than 500 copies/mL in at least one sample were classified as CMV+ reactivation. There were no discernible variations in the BAFF-R and TACI transcript expression levels. In the CMV+ group, we examined the relationship between the transcript levels and peak viremia. Peak viremia levels and BCMA transcript levels showed a strong correlation. BAFF-R and TACI expressions showed no measurable differences. In patients with early CMV reactivation, high BCMA receptor expression was associated with increased plasmablast, lymphocyte B cell class-switched levels (LBCS), and viral load. Our findings demonstrate that pre-KT BCMA transcript levels increased in KT recipients with early CMV reactivation. These transcript levels positively correlate with peak viremia and weakly with plasmablast and LBCS levels in PBLs.

Successful Combination of Remdesivir and Convalescent Plasma to Treat a Patient with Rituximab-Related B-Cell Deficiency and Prolonged COVID-19: A Case Report

Background:

Treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in immuno-compromised patients with complete B cell depletion can be really challenging due to the lack of seroconversion and long-lasting disease.

Case Report:

We describe a case of long-lasting coronavirus disease (COVID-19) in a female patient with rheumatoid arthritis who was treated with rituximab and continued to show B-cell depletion. An ongoing replication of SARS-CoV-2 was demonstrated for a period of 8 months when nasopharyngeal swabs were tested. She was treated once with remdesivir but without lasting resolution, and she was then treated with convalescent plasma but with a similar effect. Only with a combination of both treatments was clinical resolution achieved. The patient's lack of seroconversion and the prolonged course of the disease illustrate the importance of humoral immunity in resolving SARS-CoV-2 infection. This case report highlights challenges in managing immunocompromised hosts, who may act as persistent shedders and sources of transmission.

Conclusions:

The combination of remdesivir and convalescent plasma resulted in successfully achieving clinical resolution of SARS-CoV-2 infection in our patient.

Clinical Significance of the Pre-Transplant CXCR3 and CCR6 Expression on T Cells In Kidney Graft Recipients

BACKGROUND

T cells play a fundamental role in the processes that mediate graft rejection, tolerance, and defense against infections. The CXCR3 and CCR6 receptors, highly expressed in Th1 (type 1 T helper cells)/Tc1 (T cytotoxic cells, type 1), Th1-Tc1, and Th17-Tc17 lymphocytes, respectively, participate in cell migration toward inflamed tissues. The altered expression level of CXCR3 and CCR6 has been associated with different clinical events after renal transplantation, such as acute rejection (AR) and chronic graft dysfunction, but data are still limited. In this study, we evaluated the expression of the receptor CXCR3 and CCR6 in peripheral blood T lymphocytes from kidney transplant recipients (KTR) and their association with viral infections, AR, and allograft function.

METHODS

Through flow cytometry, the peripheral blood expression of CXCR3 and CCR6 in T cells was evaluated in a pretransplant collection of KTR. The levels of these T subpopulations and their association with the incidence of AR, kidney graft function, viral infections, cytomegalovirus, and BK virus were studied. Adverse clinical events and graft function were monitored during the first year post transplant.

RESULTS

KTRs with low pretransplantation levels of Th17 (CD4+CXCR3-CCR6+) (tertile 1, Th17<16.4%) had a higher risk of suffering AR during the first year post transplantation (P = .033). KTRs with viral infections or reactivations during the first 3 months post transplantation had significantly lower levels of Tc17 (CD8+CXCR3-CCR6+) and higher levels of Th1 (CD4+CXCR3+CCR6-). In patients with cytomegalovirus reactivations, the viral peak correlates negatively with the pretransplant levels of Th1 (r = -0.606, P = .037).

CONCLUSIONS

Pretransplantation assessment of Th1-Th17 and Tc1-Tc17 levels may help predict post-transplant clinical events such as AR and reactivation of viral infections.

Effect of different types of immunosuppressive therapy on the parameters of TNF receptor expression in patients with rheumatoid arthritis

   Background. The balance of TNF receptor expression on immune cells is a key factor determining cytokine-induced activation of proapoptotic or proliferative signaling pathways. As a result, the changes in cytokine level and in expression of its receptors may be one of the mechanisms that regulate the level of systemic and local inflammation in rheumatoid arthritis (RA) and determine the degree of therapy effectiveness.   The aim. To study the effect of rheumatoid arthritis therapy on the change in the patterns of TNF receptors expression in terms of co-expression and the number of receptors on the main subpopulations of immunocompetent cells.Materials and methods. A comparative analysis of the profiles of TNF receptors type 1 and 2 (TNFR1/2) co-expression was carried out in patients with RA (n = 16) before and after having inpatient effective therapy and in comparison with a group of healthy individuals (n = 21). We compared the number of receptors and the proportion of cells expressing the corresponding receptor using flow cytometry and studied the subpopulations of regulatory T cells, T cells, B cells, and monocytes.   Results. In patients with RA, there is a significant redistribution of TNFR1 and TNFR2 expression on immunocompetent cells, while the intensity of changes is associated not only with disease severity indicators, but also with the therapy received. The key adaptive mechanism of the TNF system in long-term treatment refractory course of RA is a change in the proportion of double-positive TNFR1+TNFR2+ cells, while the effectiveness of therapy and clinical indicators of the disease severity are associated with individual variability in the parameters of type 2 receptors expression.   Conclusions. The data obtained confirm the existence of a relationship between an imbalance in the expression of type 1 and type 2 TNF receptors on immunocompetent cells and the effectiveness of response to therapy. The identified patterns of typical changes in TNFR1/2 co-expression in RA can be used as potential therapeutic targets and predictive factors for the effectiveness of therapy.

Monitoring of Soluble Forms of BAFF System (BAFF, APRIL, sR-BAFF, sTACI and sBCMA) in Kidney Transplantation

BAFF system plays an essential role in B cells homeostasis and tolerance, although it has widely not been tested in transplantation with doubtful results. The main purpose was to study the BAFF soluble forms and their correlation with acute rejection (AR) and donor-specific antibodies production. Serum levels of BAFF, APRIL, and soluble forms of their receptors were analyzed in renal recipients with and without acute rejection (AR/NAR) appearance. All molecules were evaluated at pre- and post-transplantation. sTACI showed a significant correlation with BAFF and sR-BAFF levels, and sBCMA also showed a positive correlation with sAPRIL levels. A significant increase in sAPRIL levels in patients suffering AR was also found, and ROC curves analysis showed an AUC = 0.724, a concentration of 6.05 ng/ml (sensitivity: 66.7%; specificity: 73.3%), the best cutoff point for predicting AR. In the post-transplant dynamics of sAPRIL levels in the longitudinal cohort, we observed a significant decrease at 3 and 6 month post-transplantation compared to pretransplantation status. We also observed that recipients with high pre-transplant levels of sAPRIL generated antibodies earlier than those with lower sAPRIL levels, although their long-term post-transplantation was not different. Our results show that elevated serum levels of APRIL may be helpful as a biomarker for the diagnosis of AR, although the longitudinal study shows that it is not helpful as a prognostic biomarker.

Evaluating the Link between BAFF System Gene Expression and Acute Rejection Development in Kidney Transplantation

B-cell activating factor (BAFF) system signaling is critical for B-cell homeostasis, effector functions, and tolerance maintenance in transplants, but it has not been studied in kidney transplant recipients (KTRs). The aim was to analyze the changes in BAFF system expression in KTRs with/without acute rejection (AR/NAR). The BAFF system expression was analyzed by qPCR in 40 KTRs. A meta-analysis of BAFF system expression and histological renal damage was identified by the Chronic Allograft Damage Index (CADI) and performed from the GEO database. Proliferation-inducing ligand (APRIL) expression increased at three- and six-months post-KT (p = 0.014 and p < 0.001). B-cell maturation antigen (BCMA) expression increased at six-months post-KT (p = 0.038). BAFF expression remained stable in NAR-KTRs, but was increased in CADI concerning the No-CADI group at one year (p = 0.008). BCMA expression increased in the CADI group at one- (p = 0.001) and six-years post-KT (p = 0.024). At three months, the transmembrane activator and calcium modulator interactor (TACI) gene significantly elevated KTRs with DSAs (donor-specific antibody; p = 0.034). KTRs with DSAs significantly increase the B-cell activating factor receptor (R-BAFF; p = 0.021) and TACI (p = 0.018) between pre- and three-month post-KT. Changes in the expression of the BAFF system increase during post-KTR in the development of AR and chronic allograft damage, and could be an important pathological tool to detect and prevent kidney graft outcomes.

Tertiary Lymphatic Structures in Primary Hepatic Carcinoma: Controversy Cannot Overshadow Hope

Tertiary lymphoid structures (TLSs) are organized aggregates of immune cells found in the tumor microenvironment. TLS can influence primary hepatic carcinoma (PHC) occurrence and have an active role in cancer. TLS can promote or inhibit the growth of PHC depending on their location, and although available findings are controversial, they suggest that TLS have a protective role in PHC tissues and a non-protective role in paracancerous tissues. In addition, the cellular composition of TLS can also influence the outcome of PHC. As an immunity marker, TLS can act as a marker of immunotherapy to predict its effect and help to identify patients who will respond well to immunotherapy. Modulation of TLS formation through the use of chemokines/cytokines, immunotherapy, or induction of high endothelial vein to interfere with tumor growth has been studied extensively in PHC and other cancers. In addition, new tools such as genetic interventions, cellular crosstalk, preoperative radiotherapy, and advances in materials science have been shown to influence the prognosis of malignant tumors by modulating TLS production. These can also be used to develop PHC treatment.

Splenic B1 B Cells Acquire a Proliferative and Anti-Inflamatory Profile During Pregnancy in Mice

B cells are a heterogeneous cell population with differential ontogeny, anatomical location, and functions. B1 B cells are a distinct subpopulation characterized by their unique capacity of self-renewal, the production of large quantities of IL-10, and the ability to secrete protective, anti-inflammatory natural antibodies (NAbs), presumably upon down-regulation of CD1d expression. Although natural antibodies are thought to be protective, due to their polyreactivity, their participation in certain autoimmune diseases has been suggested. In the context of pregnancy, the role of B1 B cells has been discussed controversially. While in human pregnancies B1 B cells and natural/polyreactive antibodies they produce are involved in the development of preeclampsia, in mice they promote healthy gestation and fetal protection. In this work, we aimed to functionally characterize the splenic B1 B cell population during pregnancy in mice. Functional enrichment analysis using only up-regulated transcripts from a transcriptomic profile performed on total splenic B cells from pregnant compared to non-pregnant mice showed augmented cell cycle and DNA replication pathways. Proliferation studies by flow cytometry showed augmented Ki-67 proliferation marker expression and percentages of B1 B cells. Furthermore, B1 B cells produced higher levels of IL-10 and lower levels of TNF-α leading to an increased IL-10/TNF-α ratio and showing an immunoregulatory phenotype. Finally, we observed lower expression of CD1d on B1 B cells, suggesting a higher capacity to produce NAbs in the context of pregnancy. In summary, our results showed not only an expanded and proliferative splenic B1 B cell population during pregnancy but also the acquisition of immunomodulatory capacities suggesting its critical role in the intricate process of pregnancy tolerance.

Personalized Medicine for Kidney Transplantation: Association of Graft Survival and Acute Transplant Rejection with Genetic Variation in B Cell Activating Factor System Signaling

Kidney transplantation (KT) clinical outcomes are highly variable across patients and would benefit from predictive biomarkers to achieve personalized/precision medicine. The B cell activating factor (BAFF) system signaling plays an essential role in B lymphocytes' homeostasis, and is implicated in activation and survival of B lymphocytes. Single nucleotide polymorphisms (SNPs) in BAFF system genes are therefore strong candidates to identify the genetic mechanisms underpinning variable clinical outcomes in KT. We report here new findings on BAFF system genetic polymorphisms in KT patients in relation to two key phenotypes of clinical interest: graft survival and acute rejection (AR). A total of 168 KT patients, of which 29 suffered AR, participated in this study. The BAFF system polymorphisms in five genes TNFSF13B, TNFSF13, TNFRSF13C, TNFRSF13B, and TNFRSF17 were characterized using TaqMan SNP genotyping. Patients with KT who had an AA genotype in polymorphism rs3803800 of the TNFSF13 gene had a higher risk of suffering AR (p = 0.046; odds ratios = 3.38, 95% CI: 1.02-11.2). Moreover, patients with AA genotype (rs3803800) in the TNFSF13 gene had a significantly lower AR-free time than the GG/GA genotypes (69.2% vs. 85.7%; p = 0.037). Of importance, bioinformatics analysis showed that the polymorphism rs3803800 could alter splicing regulation and affect the proliferation-inducing ligand (APRIL) expression levels. The analysis of graft survival did not show a significant association with the polymorphisms analyzed in this study. In conclusion, the rs3803800 genetic polymorphism from this study of BAFF system genes appears to display importance in AR-free time for KT patients, and thus, warrants further research in independent populations as a putative predictive biomarker of AR. These findings also inform future personalized/precision medicine efforts and functional genomic studies in KT patients.

Mechanistic insights into the role of B cells in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease epitomized by severe inflammation that induces tendon, cartilage, and bone damage over time. Although different types of cells undertake pathogenic functions in RA, the B cell's significant involvement has increasingly been known following the development of rheumatoid factor and it has been re-emphasized in recent years. Therefore, the rheumatoid factors and anti-cyclic citrullinated peptide antibodies are well-known indications of infection and clinical manifestations, and that they can precede the development of illness by several years. The emergence of rituximab a B cell reducing chimeric antidote in 1997 and 1998 transformed B-cell-targeted therapy for inflammatory disorder from a research hypothesis to a functional fact. Ever since, several autoantibody-related conditions were addressed, including the more intriguing indications of effectiveness seen in rheumatoid arthritis patients. Numerous types of B-cell-targeted compounds are currently being researched. From the beginning, one of the primary goals of B-cell therapy was to reinstate some kind of immune tolerance. While B cells have long been recognized as essential autoantibody producers, certain antibody-independent functions and usefulness as a key targeted therapy were not recognized until recently. The knowledge of B cells' diverse physical and pathogenic roles in autoimmune diseases is growing. As a result, the number of successful agents targeting the B cell complex is becoming more ubiquitous. Therefore, in this article, we explore fresh perspectives upon the roles of B cells in arthritis treatment, as well as new evidence regarding the effectiveness of B lymphocytes reduction and the therapeutic outcome of biological markers.

Monitoring of B Cell in Kidney Transplantation: Development of a Novel Clusters Analysis and Role of Transitional B Cells in Transplant Outcome

Background: B lymphocytes (BL) seem to play an important role in transplantation, although the and role of different subpopulations in monitoring and outcome is not clear. Our aim was to monitoring immunological profiles based on BL subpopulations in kidney recipients (KR) with the risk of acute rejection (AR). Methods: Monitoring of BL subpopulations was performed by flow cytometry in PBLs before transplantation and three and six months after transplantation (PTX). We used two methodological approaches, a traditional analysis, and a novel cluster analysis, to determine the association between BL subpopulations, AR incidence, and graft function. Results: After three months of PTX, KRs with a B phenotype enriched in transitional BL and plasmablasts had better kidney function and lower AR incidence. KRs with decreased transitional BL and plasmablasts were associated with lower kidney function and higher AR PTX. KRs that had an increase in transitional BL PTX had a better clinical outcome. The increase in transitory BL during PTX was also associated with an increase in Tregs. Indeed, KRs receiving thymoglobulin as induction therapy showed a slight decrease in the relative frequency of naive BLs after three months of PTX. Conclusion: The monitoring of BL subpopulations may serve as a non-invasive tool to improve immunological follow-up of patients after kidney transplantation. However, further studies are needed to confirm the obtained results, define cut-off values, and standardize more optimal and even custom/customized protocols.

The Antidepressant Mirtazapine Rapidly Shifts Hepatic B Cell Populations and Functional Cytokine Signatures in the Mouse

Introduction

B cells are important regulators of both adaptive and innate immunity. The normal liver contains significant numbers of B cells, and their numbers increase dramatically in immune-mediated liver diseases. Our previous observations suggest a hepatoprotective effect of the antidepressant mirtazapine in human and experimental immune-mediated liver disease. Therefore, we performed a series of experiments to determine the impact of mirtazapine treatment on hepatic B cell homeostasis, as reflected by B cell number, trafficking and phenotype using flow cytometry (FCM) and intravital microscopy (IVM) analysis. Mirtazapine treatment rapidly induced a significant reduction in total hepatic B cell numbers, paralleled by a compositional shift in the predominant hepatic B cell subtype from B2 to B1. This shift in hepatic B cells induced by mirtazapine treatment was associated with a striking increase in total hepatic levels of the chemokine CXCL10, and increased production of CXCL10 by hepatic macrophages and dendritic cells. Furthermore, mirtazapine treatment led to an upregulation of CXCR3, the cognate chemokine receptor for CXCL10, on hepatic B cells that remained in the liver post-mirtazapine. A significant role for CXCR3 in the hepatic retention of B cells post-mirtazapine was confirmed using CXCR3 receptor blockade. In addition, B cells remaining in the liver post-mirtazapine produced lower amounts of the proinflammatory Th1-like cytokines IFNγ, TNFα, and IL-6, and increased amounts of the Th2-like cytokine IL-4, after stimulation in vitro.

Conclusion

Mirtazapine treatment rapidly alters hepatic B cell populations, enhancing hepatic retention of CXCR3-expressing innate-like B cells that generate a more anti-inflammatory cytokine profile. Mirtazapine-induced hepatic B cell shifts could potentially represent a novel therapeutic approach to immune-mediated liver diseases characterized by B cell driven pathology.

High rates of severe disease and death due to SARS-CoV-2 infection in rheumatic disease patients treated with rituximab: a descriptive study

The objective of this study is to describe the characteristics and outcomes of rheumatic and musculoskeletal disease (RMD) patients who were treated with rituximab and had suspected or confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this descriptive study, RMD patients who were treated with rituximab in the last 12 months at the Rheumatology Department of our hospital were screened for SARS-CoV-2 infection via telephone interview and a comprehensive review of clinical health records (01/02/2020–26/05/2020). Those with probable or confirmed SARS-CoV-2 infection were included. In total, 76 patients were screened. Of these, 13 (17.1%) had suspected or confirmed SARS-CoV-2 infection. With regard to these 13 patients, the median age at coronavirus disease (COVID-19) diagnosis was 68 years (range 28–76 years) and 8 (61.5%) were female. Five patients had rheumatoid arthritis, three had systemic vasculitis, two had Sjögren syndrome, and two had systemic lupus erythematosus. Additionally, seven patients (53.8%) had pulmonary involvement secondary to RMD. Eight patients (61.5%) developed severe disease leading to hospitalization, and seven developed bilateral pneumonia and respiratory insufficiency. Of the eight hospitalized patients, five (62.5%) fulfilled the acute respiratory distress syndrome criteria and three developed a critical disease and died. Our cohort had a high rate of severe disease requiring hospitalization (61.5%), with bilateral pneumonia and hyperinflammation leading to a high mortality rate (23.1%). Treatment with rituximab should be considered a possible risk factor for unfavorable outcomes in COVID-19 patients with RMD. However, further study is required to confirm this association.

The Contribution of B Cells in Autoimmune Liver Diseases

Autoreactive B cells can promote autoimmunity through antigen presentation to autoreactive T cells, production of autoantibodies, generation of cytokines promoting T cell activation and differentiation, and inhibition of regulatory T cells and B cells. Here, the authors highlight studies pertaining to B cell mechanisms associated with disease pathogenesis and outcomes in autoimmune hepatitis and the immune-mediated cholangiopathies (primary biliary cholangitis, primary sclerosing cholangitis, and biliary atresia). The vast majority of investigations focus on autoantibodies and future research endeavors should include deciphering the role of the B cell in T cell activation (through antigen presentation, cytokine/chemokine production, and inhibition of regulation). Targeting B cell mechanisms in the treatment of autoimmune liver diseases is also highlighted.

Interleukin 30 to Interleukin 40

Cytokines are important molecules that regulate the ontogeny and function of the immune system. They are small secreted proteins usually produced upon activation of cells of the immune system, including lymphocytes and myeloid cells. Many cytokines have been described, and several have been recognized as pivotal players in immune responses and in human disease. In fact, several anticytokine antibodies have proven effective therapeutics, especially in various autoimmune diseases. In the last 15 years, new cytokines have been described, and many remain poorly understood. Among the most recent cytokines discovered are interleukins-30 (IL-30) to IL-40. Several of these are members of other cytokine superfamilies, including several IL-1 superfamily members (IL-33, IL-36, IL-37, and IL-38) as well as several new members of the IL-12 family (IL-30, IL-35, and IL-39). The rest (IL-31, IL-32, IL-34, and IL-40) are encoded by genes that do not belong to any cytokine superfamily. Our aim of this review was to present a concise version of the information available on these novel cytokines to facilitate their understanding by members of the immunological community.

B-cell depletion induces a shift in self antigen specific B-cell repertoire and cytokine pattern in patients with bullous pemphigoid

Bullous Pemphigoid is the most common auto-immune bullous skin disease. It is characterized by the production of auto-antibodies directed against 2 proteins of the hemi-desmosome (BP180 and BP230). We assessed the efficacy and mechanisms of action of rituximab, an anti-CD20 monoclonal antibody, in 17 patients with severe and relapsing type of bullous pemphigoid. The phenotype, cytokine gene expression, and rearrangement of BP180-specific B-cell receptor genes were performed over 2 years following treatment. At the end of the study, 5 patients had died, 3 had withdrawn from the study, and 9 patients were in complete remission. The one- and two-year relapse rates were 44.1% (95% Confidence Interval (CI): 21.0-76.0%) and 66.5%, (95% CI: 38.4-91.4%), respectively. Phenotypic analyses confirmed dramatic B-cell depletion, which lasted for 9 to 12 months. The ELISA values of serum anti-BP180 antibodies and the frequency of BP180-specific circulating B cells decreased dramatically following treatment, which paralleled the improvement of skin lesions. During B-cell reconstitution, a polyclonal IgM repertoire appeared and a shift in the rearrangement of the B-cell receptor genes of BP180-specific circulating B cells was observed. Concurrently, we observed a decrease of IL-15, IL-6 and TNFα expressing BP180-specific B cells, and the emergence of IL-10 and IL-1RA-expressing BP180-specific IgM+ B cells in patients in complete remission off therapy, suggesting the functional plasticity of BP180-specific auto-immune B cells after rituximab treatment.

Defective T-Cell Apoptosis and T-Regulatory Cell Dysfunction in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, progressive, systemic autoimmune disease that mostly affects small and large synovial joints. At the molecular level, RA is characterized by a profoundly defective innate and adaptive immune response that results in a chronic state of inflammation. Two of the most significant alterations in T-lymphocyte (T-cell) dysfunction in RA is the perpetual activation of T-cells that result in an abnormal proliferation state which also stimulate the proliferation of fibroblasts within the joint synovial tissue. This event results in what we have termed "apoptosis resistance", which we believe is the leading cause of aberrant cell survival in RA. Finding therapies that will induce apoptosis under these conditions is one of the current goals of drug discovery. Over the past several years, a number of T-cell subsets have been identified. One of these T-cell subsets are the T-regulatory (Treg) cells. Under normal conditions Treg cells dictate the state of immune tolerance. However, in RA, the function of Treg cells become compromised resulting in Treg cell dysfunction. It has now been shown that several of the drugs employed in the medical therapy of RA can partially restore Treg cell function, which has also been associated with amelioration of the clinical symptoms of RA.

Cytokine-Producing B Cells Promote Immune-Mediated Bile Duct Injury in Murine Biliary Atresia

Biliary atresia (BA) is a neonatal T cell-mediated, inflammatory, sclerosing cholangiopathy. In the rhesus rotavirus (RRV)-induced neonatal mouse model of BA (murine BA), mice lacking B cells do not develop BA, and the lack of B cells is associated with loss of T-cell and macrophage activation. The aim of this study was to determine the mechanism of B cell-mediated immune activation (antigen presentation versus cytokine production) in murine BA. Normal neonatal B cells in the liver are predominantly at pro-B and pre-B cellular development. However, BA mice exhibit a significant increase in the number and activation status of mature liver B cells. Adoptively transferred B cells into RRV-infected, B cell-deficient mice were able to reinstate T-cell and macrophage infiltration and biliary injury. Nonetheless, neonatal liver B cells were incompetent at antigen presentation to T cells. Moreover, 3-83 immunoglobulin transgenic mice, in which B cells only present an irrelevant antigen, developed BA, indicating a B-cell antigen-independent mechanism. B cells from BA mice produced a variety of innate and adaptive immune cytokines associated with immune activation. In vitro trans-well studies revealed that BA B cells secreted cytokines that activated T cells based on increased expression of T-cell activation marker cluster of differentiation 69. Conclusion: Neonatal liver B cells are highly activated in murine BA and contribute to immune activation through production of numerous cytokines involved in innate and adaptive immunity; this work provides increased knowledge on the capacity of neonatal B cells to contribute to an inflammatory disease through cytokine-mediated mechanisms, and future studies should focus on targeting B cells as a therapeutic intervention in human BA.

Soluble antigen arrays disarm antigen-specific B cells to promote lasting immune tolerance in experimental autoimmune encephalomyelitis

Autoreactive lymphocytes that escape central immune tolerance may be silenced via an endogenous peripheral tolerance mechanism known as anergy. Antigen-specific therapies capable of inducing anergy may restore patients with autoimmune diseases to a healthy phenotype while avoiding deleterious side effects associated with global immunosuppression. Inducing anergy in B cells may be a particularly potent intervention, as B cells can contribute to autoimmune diseases through multiple mechanisms and offer the potential for direct antigen-specific targeting through the B cell receptor (BCR). Our previous results suggested autoreactive B cells may be silenced by multivalent 'soluble antigen arrays' (SAgAs), which are polymer conjugates displaying multiple copies of autoantigen with or without a secondary peptide that blocks intracellular cell-adhesion molecule-1 (ICAM-1). Here, key therapeutic molecular properties of SAgAs were identified and linked to the immunological mechanism through comprehensive cellular and in vivo analyses. We determined non-hydrolyzable 'cSAgAs' displaying multivalent 'click'-conjugated antigen more potently suppressed experimental autoimmune encephalomyelitis (EAE) compared to hydrolyzable SAgAs capable of releasing conjugated antigen. cSAgAs restored a healthy phenotype in disease-specific antigen presenting cells (APCs) by inducing an anergic response in B cells and a subset of B cells called autoimmune-associated B cells (ABCs) that act as potent APCs in autoimmune disease. Accompanied by a cytokine response skewed towards a Th2/regulatory phenotype, this generated an environment of autoantigenic tolerance. By identifying key therapeutic molecular properties and an immunological mechanism that drives SAgA efficacy, this work guides the design of antigen-specific immunotherapies capable of inducing anergy.

The Immunologic Paradoxes of IgG4-Related Disease

IgG4-related disease (IgG4-RD), which usually occurs in middle-aged and elderly men, is a newly recognized fibroinflammatory condition characterized by swelling and sclerosis of involved organs, increased IgG4-positive plasma cell infiltration in lesions, and elevated IgG4 concentration in serum. Despite growing interest in the research, the pathophysiological mechanism remains elusive. Most IgG4-RD patients respond well to steroid therapy initially, but recurrent and refractory cases are common, especially in advanced fibrotic stage. Recent studies have documented the heterogeneity of the B cell lineages, which suggests their multiple functions in IgG4-RD beyond IgG4 production, such as cytokine secretion, antigen presentation, autoantibody production, and modulation of T and B cell interactions. Thus, a critical balance exists between pathogenic and regulatory B subsets to prevent immunopathology. A prompt response to B cell depletion therapy reported in recent cases strongly suggests the imbalance within B cell lineages in IgG4-RD. A more precise understanding of the pathogenesis of IgG4-RD will open up new perspectives for therapeutic strategy. With a particular emphasis on the novel B cell-targeted therapeutic strategies, this review highlights the immunologic features of IgG4-RD and the possible roles of B cell lineages in the pathogenesis of IgG4-RD.

Immunological profile in cerebrospinal fluid of patients with multiple sclerosis after treatment switch to rituximab and compared with healthy controls

OBJECTIVE

To investigate changes in the cerebrospinal fluid (CSF) immunological profile after treatment switch from first-line injectables to rituximab in patients with relapsing-remitting MS (RRMS), and to compare the profile in MS patients with healthy controls (HC).

METHOD

Cerebrospinal fluid from 70 patients with clinically stable RRMS and 55 HC was analysed by a multiplex electrochemiluminescence method for a broad panel of cytokines and immunoactive substances before, and over a two-year period after, treatment switch to rituximab. After quality assessment of data, using a predefined algorithm, 14 analytes were included in the final analysis.

RESULTS

Ten of the 14 analytes differed significantly in MS patients compared with HC at baseline. Levels of IP-10 (CXCL10), IL-12/23p40, IL-6, sVCAM1, IL-15, sICAM1 and IL-8 (CXCL8) decreased significantly after treatment switch to rituximab. The cytokines IP-10 and IL-12/IL-23p40 displayed the largest difference versus HC at baseline and also the largest relative reduction after therapy switch to rituximab.

CONCLUSION

We found significant changes in the immunological profile after therapy switch to rituximab in RRMS in the direction towards the values of HC. IP-10 and IL12/IL-23p40 deserve further studies as part of the immunopathogenesis of MS as well as for the mode of action of rituximab in MS.

Dysfunction of CD19+CD24hiCD27+ B regulatory cells in patients with bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering skin disease characterized by the production of autoantibodies against the hemidesmosomal protein BP180. B regulatory cells (Bregs) are crucial in maintaining self-tolerance and suppressing autoantibody production. However, it is still unclear whether the dysfunctions of Bregs contributes to the autoantibody production in BP patients. In this study, we found that CD19+CD24hiCD27+ Bregs and IL-10+CD19+ Bregs were significantly increased in the peripheral blood samples of BP patients compared with that in healthy controls. Moreover, compared to Bregs from healthy individuals, we found that Bregs from BP patients fails to suppress the production of specific anti-BP180 autoantibody when co-cultured with patient-derived PBMCs. Additionally, Bregs from BP patients were defective in suppressing the CD4+ T cell proliferation and the cytokines expression (including IFN-γ, TNF-α and IL-4). Notably, we found that patient-derived Bregs produced high level of TNF-α and the TNF inhibitor etanercept could inhibit the autoantibody production in the culture system in vitro. Our results indicate that Bregs from BP patient appear phenotypically pro-inflammatory by their cytokine profile and are defective in immunosuppressive function, which suggest that Bregs play a pro-inflammatory role rather than a regulatory role in the pathogenesis of BP.

Identification of IL-40, a Novel B Cell-Associated Cytokine

We describe a novel B cell-associated cytokine, encoded by an uncharacterized gene (C17orf99; chromosome 17 open reading frame 99), that is expressed in bone marrow and fetal liver and whose expression is also induced in peripheral B cells upon activation. C17orf99 is only present in mammalian genomes, and it encodes a small (∼27-kDa) secreted protein unrelated to other cytokine families, suggesting a function in mammalian immune responses. Accordingly, C17orf99 expression is induced in the mammary gland upon the onset of lactation, and a C17orf99^-/- mouse exhibits reduced levels of IgA in the serum, gut, feces, and lactating mammary gland. C17orf99^-/- mice have smaller and fewer Peyer's patches and lower numbers of IgA-secreting cells. The microbiome of C17orf99^-/- mice exhibits altered composition, likely a consequence of the reduced levels of IgA in the gut. Although naive B cells can express C17orf99 upon activation, their production increases following culture with various cytokines, including IL-4 and TGF-β1, suggesting that differentiation can result in the expansion of C17orf99-producing B cells during some immune responses. Taken together, these observations indicate that C17orf99 encodes a novel B cell-associated cytokine, which we have called IL-40, that plays an important role in humoral immune responses and may also play a role in B cell development. Importantly, IL-40 is also expressed by human activated B cells and by several human B cell lymphomas. The latter observations suggest that it may play a role in the pathogenesis of certain human diseases.

B-cell lymphocyte kinase polymorphisms rs13277113, rs2736340, and rs4840568 and risk of autoimmune diseases: A meta-analysis

BACKGROUND

B-cell lymphocyte kinase (BLK) is an inhibitor of B cells that has an important influence on several autoimmune diseases, but there is a lack of comprehensive analysis of its association with autoimmune diseases. Hence, it is meaningful to conduct a comprehensive analysis.

METHODS

A systematic literature search was performed on the PubMed, ScienceDirect, and Web of Science databases up to June 30, 2016. The data were extracted and quality-assessed before conducting the meta-analysis. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were assessed with the STATA version 12.0 software. Subgroup and sensitivity analysis were conducted to explore potential sources of heterogeneity.

RESULTS

Altogether, 33 studies with 68,874 cases and 90,684 controls, 24 studies with 31,095 cases and 39,077 controls for rs13277113, 21 studies with 26,388 cases and 40,635 controls for rs2736340, and 4 studies with 11,391 cases and 10,972 controls for rs4840568 were included in this meta-analysis. The results revealed that the BLK rs13277113 and rs2736340 polymorphisms increased the risk of autoimmune diseases in the total analysis (A vs G: OR = 1.33, 95% CI = 1.27-1.39, P < .01; T vs C: OR = 1.34, 95% CI = 1.27-1.41, P < .01), and rs4840568 was positively associated with systemic lupus erythematosus (SLE) (A vs G: OR = 1.32, 95% CI = 1.22-1.43, P = .01).

CONCLUSION

This meta-analysis shows that the BLK (rs13277113, rs2736340, rs4840568) polymorphisms may be a risk factor for developing autoimmune diseases, especially for Asian populations and SLE.

Mercury exposure, serum antinuclear antibodies, and serum cytokine levels in the Long Island Study of Seafood Consumption: A cross-sectional study in NY, USA

Mercury (Hg) is a well-known neurotoxin, and has been more recently studied specifically as an immunotoxin. In experimental and a few epidemiologic studies, Hg has been associated with distinct cytokine profiles and antinuclear antibody (ANA) positivity, though patterns at lower levels of exposure, typical of seafood consumers with a western diet, are not well characterized. Seafood consumers (n=287) recruited on Long Island, NY completed food frequency and health questionnaires and provided blood for analysis of Hg, poly-unsaturated fatty acids (omega-3 and omega-6 fatty acids), selenium (Se), ANA, and several cytokines (IL-1β, IL-4, IL-10, TNF-α, IL-17, IFN-γ, and IL-1ra). Logistic and linear regression analyses were conducted to evaluate associations between serum Hg and cytokines and ANA. Adjusted models accounted for gender, age, ethnicity, income, education, smoking, BMI, selenium, omega-3 fatty acids, omega-6 fatty acids, omega-6/omega-3 ratio, and fish intake. Sex-stratified models were also generated with the expectation that immune profiles would differ between women and men. Median blood Hg was 4.58µg/L with 90th %ile =19.8µg/L. Nine individuals displayed ANA positivity at serum titers above 1:80; many of the cytokines were below detection limits, and the ability to detect was used in the logistic regression analyses. In linear and logistic regression analyses, Hg was not significantly associated with any of the seven investigated cytokines or with ANA-positivity. Therefore, Hg was not associated with altered immune profiles in this population of seafood consumers.

MicroRNA-22-3p as a novel regulator and therapeutic target for autoimmune diseases

MicroRNAs (miRNAs) are a class of noncoding RNAs and have emerged as critical regulators of gene expression. Some miRNAs play important roles in regulating the function of the immune system and are involved in the pathogenesis of autoimmune diseases. Recent studies suggested that microRNA-22-3p (miR-22-3p) was able to regulate the function of several types of immune cells and may be involved in the development of autoimmune diseases. We systematically reviewed relevant literatures to provide a comprehensive review of the possible roles of miR-22-3p in autoimmune diseases. Published studies suggest that miR-22-3p can act as a novel regulator of autoimmune diseases via several pathways. More studies are needed to further elucidate the exact roles of miR-22-3p in autoimmune diseases. Treatment strategy targeting miR-22-3p is also a promising therapy for autoimmune diseases.

IDO2 Modulates T Cell-Dependent Autoimmune Responses through a B Cell-Intrinsic Mechanism

Mechanistic insight into how adaptive immune responses are modified along the self-nonself continuum may offer more effective opportunities to treat autoimmune disease, cancer, and other sterile inflammatory disorders. Recent genetic studies in the KRN mouse model of rheumatoid arthritis demonstrate that the immunomodulatory molecule IDO2 modifies responses to self-antigens; however, the mechanisms involved are obscure. In this study, we show that IDO2 exerts a critical function in B cells to support the generation of autoimmunity. In experiments with IDO2-deficient mice, adoptive transplant experiments demonstrated that IDO2 expression in B cells was both necessary and sufficient to support robust arthritis development. IDO2 function in B cells was contingent on a cognate, Ag-specific interaction to exert its immunomodulatory effects on arthritis development. We confirmed a similar requirement in an established model of contact hypersensitivity, in which IDO2-expressing B cells are required for a robust inflammatory response. Mechanistic investigations showed that IDO2-deficient B cells lacked the ability to upregulate the costimulatory marker CD40, suggesting IDO2 acts at the T-B cell interface to modulate the potency of T cell help needed to promote autoantibody production. Overall, our findings revealed that IDO2 expression by B cells modulates autoimmune responses by supporting the cross talk between autoreactive T and B cells.

IL-10 from marginal zone precursor B cells controls the differentiation of Th17, Tfh and Tfr cells in transplantation tolerance

B cells are known to control CD4T cell differentiation in secondary lymphoid tissues. We hypothesized that IL-10 expression by marginal zone precursor (MZP) regulatory B cells controls the differentiation and positioning of effector and regulatory T cells during tolerization. Costimulatory blockade with donor-specific transfusion (DST) and anti-CD40L mAb in C57BL/6 mice induced tolerance to allogeneic cardiac allograft. B cell depletion or IL-10 deficiency in B cells prevented tolerance, resulting in decreased follicular regulatory CD4(+) T cells (Tfr) and increased IL-21 expression by T follicular helper (Tfh) cells in the B cell and T cell zones. IL-21 acted with IL-6 to induce CCR6(+) Th17 that caused rejection. Deficiency or blockade of IL-6, IL-21, IL-21R, or CCR6 prevented B cell depletion-induced acute cellular rejection; while agonistic mCCL20-Ig induced rejection. Adoptive transfer of IL-10(+/+) MZP in tolerogen treated CD19-Cre(+/-):IL-10(fl/fl) mice rescued the localization of Tfh and Tfr cells in the B cell follicle and prevented allograft rejection. MZP B cell IL-10 is necessary for tolerance and controls the differentiation and position of Th17, Tfh and Tfr cells in secondary lymphoid tissues. This has implications for understanding tolerance induction and how B cell depletion may prevent tolerance.

The Aryl Hydrocarbon Receptor: A Key Bridging Molecule of External and Internal Chemical Signals

The aryl hydrocarbon receptor (AhR) is a highly evolutionary conserved, ligand-activated transcription factor that is best known to mediate the toxicities of dioxins and dioxin-like compounds. Phenotype of AhR-null mice, together with the recent discovery of a variety of endogenous and plant-derived ligands, point to the integral roles of AhR in normal cell physiology, in addition to its roles in sensing the environmental chemicals. Here, we summarize the current knowledge about AhR signaling pathways, its ligands and AhR-mediated effects on cell specialization, host defense and detoxification. AhR-mediated health effects particularly in liver, immune, and nervous systems, as well as in tumorgenesis are discussed. Dioxin-initiated embryotoxicity and immunosuppressive effects in fish and birds are reviewed. Recent data demonstrate that AhR is a convergence point of multiple signaling pathways that inform the cell of its external and internal environments. As such, AhR pathway is a promising potential target for therapeutics targeting nervous, liver, and autoimmune diseases through AhR ligand-mediated interventions and other perturbations of AhR signaling. Additionally, using available laboratory data obtained on animal models, AhR-centered adverse outcome pathway analysis is useful in reexamining known and potential adverse outcomes of specific or mixed compounds on wildlife.

Inhibition of B-cell apoptosis is mediated through increased expression of Bcl-2 in patients with rheumatoid arthritis

AIM

Abnormal B-cell apoptosis is believed to have a role in rheumatoid arthritis (RA) pathogenesis, but the exact mechanisms of B-cell apoptosis in RA have not been elucidated. We therefore investigated the percentage of circulating B cells and its relationship with apoptosis in a cohort of patients with RA.

METHODS

B cells were quantified by flow cytometry in RA patients and matched controls, and the relationships between these proportions and RA disease parameters were calculated. Rates of apoptosis were determined by annexin V/propidium iodine analysis, and Bcl-2 and caspase-3 protein levels were determined by western blot.

RESULTS

RA patients had significantly higher percentage of B cells in the peripheral blood than healthy controls but a significantly lower rate of B-cell apoptosis. The percentage of B cells correlated with Disease Activity Score of 28 joints and serum immunoglobulin G concentration in RA patients. Expression of anti-apoptosis protein Bcl-2 was higher in RA patients than in healthy controls, whereas expression of apoptosis marker caspase-3 in B cells was lower.

CONCLUSION

The higher percentage of B cells in the peripheral blood of RA patients may be due, at least partially, to disruption of the normal pathway of apoptosis in these cells. The inhibition of B-cell apoptosis in these patients may be attributable to the enhanced expression of Bcl-2 in these cells.

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 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.

B cells responses and cytokine production are regulated by their immune microenvironment

The adaptive immune system consists of two types of lymphocytes: T and B cells. These two lymphocytes originate from a common precursor, yet are fundamentally different with B cells mediating humoral immunity while T cells mediate cell mediated immunity. In cytokine production, naïve T cells produce multiple cytokines upon activation while naïve activated B cells do not. B cells are capable of producing cytokines, but their cytokine production depends on their differentiation state and activation conditions. Hence, unlike T cells that can produce a large amount of cytokines upon activation, B cells require specific differentiation and activation conditions to produce cytokines. Many cytokines act on B cells as well. Here, we discuss several cytokines and their effects on B cells including: Interleukins, IL-7, IL-4, IL-6, IL-10, and Interferons, IFN-α, IFN-β, IFN-γ. These cytokines play important roles in the development, survival, differentiation and/or proliferation of B cells. Certain chemokines also play important roles in B cell function, namely antibody production. As an example, we discuss CCL28, a chemokine that directs the migration of plasma cells to mucosal sites. We conclude with a brief overview of B cells as cytokine producers and their likely functional consequences on the immune response.

Contribution of autoallergy to the pathogenesis in the NOD mice

The immunoglobulin isotype IgE is commonly associated with allergy. However, its involvement in autoimmune disease in general, and Type 1 diabetes (T1D) in particular, is still not completely clarified, nonetheless IgE has been observed in patients with T1D. In this article, we aimed to elucidate the contribution of IgE in the pathogenesis of the disease in a spontaneous model for T1D, i.e. the NOD mouse. We observed increased levels of IgE in splenic, lymph node and peripheral blood B cells in the NOD mice compared to the control C57BL/6 (B6) mice. No correlation was found between the IgE levels on B cells and those in the sera of these mice, indicating a B cell intrinsic property mediating IgE capture in NOD. Functionally, the B cells from NOD were similar to B6 in rescuing the IgE-mediated immune response via the low affinity receptor CD23 in a transgenic adoptive transfer system. However, the involvement of IgE in diabetes development was clearly demonstrated, as treatment with anti-IgE antibodies delayed the incidence of the diabetes in the NOD mice compared to the PBS treated group. Pancreas sections from a 13-week-old NOD revealed the presence of tertiary lymphoid structures with T cells, B cells, germinal centers and IgE suggesting the presence of autoantigen specific IgE. Our study provides an insight to the commonly overlooked immunoglobulin IgE and its potential role in autoimmunity.

B cells produce less IL-10, IL-6 and TNF-α in myasthenia gravis

B cells from myasthenia gravis (MG) patients with autoantibodies (Aab) against acetylcholine receptor (AChR), muscle-specific kinase (MuSK) or with no detectable Aab were investigated as cytokine producing cells in this study. B cells were evaluated for memory phenotypes and expressions of IL-10, IL-6 and IL-12A. Induced productions of IL-10, IL-6, IL-12p40, TNF-α and LT from isolated B cells in vitro were measured by immunoassays. MG patients receiving immunosuppressive treatment had higher proportions of memory B cells compared with healthy controls and untreated patients. With CD40 stimulation MG patients produced significantly lower levels of IL-10, IL-6. With CD40 and B cell receptor stimulation of B cells, TNF-α production also decreased in addition to these cytokines. The lower levels of these cytokine productions were not related to treatment. Our results confirm a disturbance of B cell subpopulations in MG subgroups on immunosuppressive treatment. B cell derived IL-10, IL-6 and TNF-α are down-regulated in MG, irrespective of different antibody productions. Ineffective cytokine production by B cells may be a susceptibility factor in dysregulation of autoimmune Aab production.

CD20+ B cell depletion in systemic autoimmune diseases: common mechanism of inhibition or disease-specific effect on humoral immunity?

Autoimmunity remains a complex physiologic deviation, enabled and perpetuated by a variety of interplayers and pathways. Simplistic approaches, targeting either isolated end-effectors of more centrally placed interactors of these mechanisms, are continuously tried in an effort to comprehend and halt cascades with potential disabling and deleterious effects in the affected individuals. This review focuses on theoretical and clinically proved effects of rituximab-induced CD20+ B cell depletion on different systemic autoimmune diseases and extrapolates on pathogenetic mechanisms that may account for different interindividual or interdisease responses.

B-cell hyperactivity in primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is characterized by mononuclear inflammatory infiltrates and IgG plasma cells in salivary and lacrimal glands which lead to irreversible destruction of the glandular tissue and is accompanied by sensation of dryness of mouth and eyes. B cells play a central role in the immunopathogenesis and exhibit signs of hyperactivity. Hyperactivity of B cells is the consequence of the coordinated and integrated action of stimulation of the B-cell receptor, CD40 and toll-like receptors in the presence of appropriate cytokines. As discussed, overexpression of type I IFN and BAFF on one hand and IL-6 and IL-21 on the other hand are critically involved in the enhanced plasma cell formation in pSS patients. Hyperactivity of B cells results in secretion of autoantibodies and production of various cytokines. These insights in the role of B cells in the pathogenetic process of pSS offer ample targets for successful therapeutical intervention in pSS.