Reduced numbers of regulatory B cells are negatively correlated with disease activity in patients with new-onset rheumatoid arthritis

Transitional and CD21- PD-1+ B cells are associated with remission in early rheumatoid arthritis

BACKGROUND

Early initiation of effective treatment is associated with positive long-term prognosis for patients with rheumatoid arthritis (RA). Currently, there are no biomarkers in clinical use to predict treatment response. A predictor of treatment response may be the B-cell compartment, as this is altered in RA patients, making it a potential candidate for predicting treatment response. In this study, we sought to identify B-cell subset(s) at diagnosis that might be associated with Clinical Disease Activity Index (CDAI) remission at 24-week follow-up.

METHODS

Seventy early RA patients from the NORD-STAR trial, recruited from two Swedish sites, and 28 matched healthy controls, were included in this spin-off study. In NORD-STAR, all patients were randomized to methotrexate (MTX) combined with 1) prednisolone, 2) anti-TNF (certolizumab-pegol), 3) CTLA4-Ig (abatacept), or 4) anti-IL-6R (tocilizumab). Circulating B-cell subsets at diagnosis were assessed by flow cytometry. The primary outcome measure was remission according to CDAI ≤ 2.8. A multivariate two-part discriminant analysis was performed to assess whether B-cell subpopulations at diagnosis could predict remission at 24 weeks. Subsequent univariable statistical analyses were performed using t-tests, Mann-Whitney U, or Kruskal-Wallis tests, as appropriate. Correlations were analyzed using Spearman or Pearson tests, depending on data type. The impact of specific B-cell populations on remission at week 24 was assessed using logistic regression models. The logistic regression model was also used to simultaneously visualize the sensitivity and specificity of the model for all possible values of the exposure (B-cell subpopulations) in predicting the outcome.

RESULTS

Patients who achieved CDAI remission at 24 weeks had higher proportions of transitional (p < 0.01) and CD21- PD-1+ (p < 0.01) B cells at diagnosis compared to those who did not. When the two B-cell populations were combined, the sensitivity and specificity for remission, including all treatment arms, were 59% and 86%, respectively. Stratification of the patients by treatment arm revealed a significant negative correlation between the proportion of transitional B cells at baseline and disease activity after 24 weeks of treatment with either MTX and prednisolone or anti-IL-6R.

CONCLUSIONS

Our results indicate that transitional and CD21- PD-1+ B cells are associated with remission in early RA.

CLINICAL TRIAL NUMBER

Not applicable.

Roles of Immunity and Endogenous Retroelements in the Pathogenesis of Rheumatoid Arthritis and Treatment Strategies

Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disease that primarily affects the joints. RA usually results in synovial hyperplasia, expansion of "pannus" and destruction of cartilage. The etiology and pathogenesis of RA are not fully understood, but immunity has been shown to play an important role in the development of autoimmune diseases such as RA. In addition, endogenous retroelements, the remnants of ancient retroviruses in the human genome, are involved in cancer and/or immune disorders. As evidenced by increasing evidences that the aberrant expression of retroelements induces innate immunity, despite the fact that the expression of most retroelements has been epigenetically suppressed over a long period of evolution. With the continuous development of disease-modifying anti-rheumatic drugs (DMARDs), RA disease activity has been alleviated and improved. Unfortunately, some patients have a limited response to DMARDs, and the drugs also have the disadvantages of some side effects and high economic costs. This review summarizes the pathogenic mechanisms of RA and endogenous retroelements in autoimmunity, and concludes with a summary of treatments for RA, along with new therapeutic recommendations.

PD-L1+ Regulatory B Cells from Rheumatoid Arthritis Patients Have Impaired Function in Suppressing IFN-ү and IL-21 Production

Rheumatoid arthritis (RA) is a systemic inflammatory autoimmune disease. The pathomechanism of RA depends on both B and T cells. Regulatory B cells (Breg) have been shown to suppress T-cell immune responses and play a key role in modulating autoimmune processes. We aimed to investigate the possibility of utilizing PD-L1+ Breg cells in downregulating the Th cells' immune response in healthy individuals and RA patients. We hypothesized that the PD-1/PD-1L interaction plays a key role in this process, which may be defective in autoimmune diseases. We separated T and B cells from the peripheral blood of healthy volunteers and RA patients by magnetic cell sorting, and Th cells and Treg cells were isolated by fluorescence-activated cell sorting. The cytokine production by CD4+ Th cells was detected by intracellular flow cytometry. CpG and CD40L stimulations were applied to induce PD-L1hi expressing Breg cells. We found that the frequency of PD-L1hi cells is significantly lower in all B-cell subsets in RA compared to healthy controls. Functional analysis of induced PD-L1+ Breg cells in coculture with activated autologous Th cells has shown that healthy control samples containing higher levels of PD-L1hi Breg cells significantly inhibit IFN-ү and IL-21 production by Th cells. In contrast, RA patients' samples with lower levels of PD-L1hi Breg cells failed to do so. Since the expression of PD-L1 on B cells can be modulated in vitro to induce Breg cell suppressive capacity, these data may provide new perspectives for future therapy for RA.

Emerging roles of checkpoint molecules on B cells

Immune checkpoint molecules, including both co-inhibitory molecules and co-stimulatory molecules, are known to play critical roles in regulating T-cell responses. During the last decades, immunotherapies targeting these molecules (such as programmed cell death 1 (PD-1), and lymphocyte activation gene 3 (LAG-3)) have provided clinical benefits in many cancers. It is becoming apparent that not only T cells, but also B cells have a capacity to express some checkpoint molecules. These were originally thought to be only the markers for regulatory B cells which produce IL-10, but recent studies suggest that these molecules (especially T-cell immunoglobulin and mucin domain 1 (TIM-1), T cell immunoreceptor with Ig and ITIM domains (TIGIT), and PD-1) can regulate intrinsic B-cell activation and functions. Here, we focus on these molecules and summarize their characteristics, ligands, and functions on B cells.

Revolutionizing rheumatoid arthritis therapy: harnessing cytomembrane biomimetic nanoparticles for novel treatment strategies

Rheumatoid arthritis (RA) is a systemic immune disease with severe implications for joint health. The issue of non-specific drug distribution potentially limits the therapeutic efficacy and increases the risk associated with RA treatment. Researchers employed cytomembrane-coated biomimetic nanoparticles (NPs) to enhance the targeting delivery efficacy to meet the demand for drug accumulation within the affected joints. Furthermore, distinct cytomembranes offer unique functionalities, such as immune cell activation and augmented NP biocompatibility. In this review, the current strategies of RA treatments were summarized in detail, and then an overview of RA's pathogenesis and the methodologies for producing cytomembrane-coated biomimetic NPs was provided. The application of cytomembrane biomimetic NPs derived from various cell sources in RA therapy is explored, highlighting the distinctive attributes of individual cytomembranes as well as hybrid membrane configurations. Through this comprehensive assessment of cytomembrane biomimetic NPs, we elucidate the prospective applications and challenges in the realm of RA therapy, and the strategy of combined therapy is proposed. In the future, cytomembrane biomimetic NPs have a broad therapeutic prospect for RA.

Application Value of Platelet-to-Lymphocyte Ratio as a Novel Indicator in Rheumatoid Arthritis: A Review Based on Clinical Evidence

Rheumatoid arthritis (RA) is a chronically progressive autoimmune disease with increasing age-standardized prevalence and incidence of RA worldwide. Its pathological features are persistent synovitis of the joint, accompanied by the release of a large number of inflammatory cytokines and cartilage and bone destruction. RA can lead to progressive joint damage, stiffness and swelling, vascular and bone-related complications, and irreversible disability, which seriously affects patients' life treatment. Early diagnosis and treatment can enhance the quality of life of RA patients. Platelet-to-lymphocyte ratio (PLR), as a common indicator in routine blood tests, has been proposed as an indicator of systemic inflammation in recent years. Its clinical detection is less invasive, economical, rapid and simple, and has been applied to the clinical evaluation of a variety of diseases. Of note, this indicator is important in assessing disease activity in RA, co-diagnosing RA, detecting subclinical complications, and monitoring responses to anti-inflammatory therapy. Therefore, this review summarizes the relationship between PLR and RA and the relevant mechanisms, further advancing the understanding of the clinical value of PLR.

Lymphocyte subset phenotyping for the prediction of progression to inflammatory arthritis in anti-citrullinated-peptide antibody-positive at-risk individuals

OBJECTIVES

Inflammatory arthritis (IA) is considered the last stage of a disease continuum, where features of systemic autoimmunity can appear years before clinical synovitis. Time to progression to IA varies considerably between at-risk individuals, therefore the identification of biomarkers predictive of progression is of major importance. We previously reported on the value of three CD4+T cell subsets as biomarkers of progression. Here, we aim to establish the value of 18 lymphocyte subsets (LS) for predicting progression to IA.

METHODS

Participants were recruited based on a new musculoskeletal complaint and being positive for anti-citrullinated-peptide antibody. Progression (over 10 years) was defined as the development of clinical synovitis. LS analysis was performed for lymphocyte lineages, naive/memory subsets, inflammation-related cells (IRC) and regulatory cells (Treg/B-reg). Modelling used logistic/Cox regressions.

RESULTS

Of 210 patients included, 93 (44%) progressed to IA, 41/93 (44%) within 12 months (rapid progressors). A total of 5/18 LS were associated with progression [Treg/CD4-naïve/IRC (adjusted P < 0.0001), CD8 (P = 0.021), B-reg (P = 0.015)] and three trends (NK-cells/memory-B-cells/plasmablasts). Unsupervised hierarchical clustering using these eight subsets segregated three clusters of patients, one cluster being enriched [63/109(58%)] and one poor [10/45(22%)] in progressors. Combining all clinical and LS variables, forward logistic regression predicted progression with accuracy = 85.7% and AUC = 0.911, selecting smoking/rheumatoid-factor/HLA-shared-epitope/tender-joint-count-78 and Treg/CD4-naive/CD8/NK-cells/B-reg/plasmablasts. To predict rapid progression, a Cox regression was performed resulting in a model combining smoking/rheumatoid factor and IRC/CD4-naive/Treg/NK-cells/CD8+T cells (AUC = 0.794).

CONCLUSION

Overall, progression was predicted by specific LS, suggesting potential triggers for events leading to the development of IA, while rapid progression was associated with a different set of subsets.

Reversing the Inflammatory Process-25 Years of Tumor Necrosis Factor-α Inhibitors

Immune-mediated inflammatory diseases, such as rheumatoid arthritis, psoriatic arthritis, peripheral and/or axial spondyloarthritis, Crohn's disease, and ulcerative colitis, are characterized by molecular and cellular changes in the immune system. Due to the systemic nature of these diseases, organs such as the liver or cardiovascular system are often affected by the inflammatory process. Tumor necrosis factor-α inhibitor therapy reduces the activation of pro-inflammatory signaling cascades, mitigates the chronic inflammatory process by restoring cellular balance, and alleviates clinical consequences, such as pain and tissue damage.

Rheumatoid arthritis and osteoimmunology: The adverse impact of a deregulated immune system on bone metabolism

The term osteoimmunology describes an interdisciplinary research field that links the investigation of osteology (bone cells) with immunology. The crosstalk between innate and adaptive immune cells and cells involved in bone remodeling, mainly bone-resorbing osteoclasts and bone-forming osteoblasts, becomes particularly obvious in the inflammatory autoimmune disease rheumatoid arthritis (RA). Besides striking inflammation of the joints, RA causes bone loss, leading to joint damage and disabilities as well as generalized osteoporosis. Mechanistically, RA-associated immune cells (macrophages, T cells, B cells etc.) produce high levels of pro-inflammatory cytokines, receptor activator of nuclear factor κB ligand (RANKL) and autoantibodies that promote bone degradation and at the same time counteract new bone formation. Today, antirheumatic therapy effectively ceases joint inflammation and arrests bone erosion. However, the repair of established bone lesions still presents a challenging task and requires improved treatment options. In this review, we outline the knowledge gained over the past years about the immunopathogenesis of RA and the impact of a dysregulated immune system on bone metabolism.

Predictive Value of B reg and Serum IL-10 Concentration Levels for Acute ITP Progression to Chronic Phase

INTRODUCTION

Pediatric immune thrombocytopenia (ITP) is a potentially life threating autoimmune disorder with different responses to therapy and different bleeding phenotypes in critical organs. The molecular basis for the variable response has not yet been fully elucidated. This study was designed to address the predictive value of regulatory B-cell (B reg ) count and interleukin-10 (IL-10) serum levels for acute ITP patients who progress to chronic phase. The present study included 80 children with acute ITP )38 males and 42 females (with median age of 8 years and 40 matched healthy controls. Assessment of B reg (CD19 + CD24 hi CD38 hi ) was carried out by a multicolor flowcytometry, however, IL-10 serum levels were evaluated by enzyme-linked immunosorbent assay. A significant reduction of B reg percentage and a significant increase in serum IL-10 levels were identified in children with acute ITP as compared with controls ( P <0.001 for both). Fourteen ITP patients passed to chronic phase, while 66 patients achieved remission within 6 months. The absolute B reg was significantly lower, while IL-10 was significantly higher in patients with acute ITP who progressed to chronic phase in comparison with acute ITP patients who achieved complete remission. Cox proportional hazards for ITP chronicity revealed that IL-10 OR was 2.46 (confidence interval: 1.42-4.27; P =0.001) and absolute B reg OR was 0.147 (confidence interval: 0.128-0.624; P =0.005) in the peripheral blood. Therefore, they could predict chronicity in ITP cases.

CONCLUSION

Reduced B reg count and elevated IL-10 levels in patients with acute ITP at diagnosis can predict chronicity.

Pulmonary fibrosis associated with rheumatoid arthritis: from pathophysiology to treatment strategies

INTRODUCTION

Rheumatoid arthritis (RA) is the most common inflammatory autoimmune disease, characterised by symmetric destructive arthritis and synovitis. Lung involvement is frequent, including in the form of interstitial lung disease (ILD). RA-ILD often presents with a radiologic and pathologic pattern of usual interstitial pneumonia, similar to idiopathic pulmonary fibrosis, highlighting the similarities between the two diseases, but other patterns and pathological associations are described.

AREAS COVERED

This article reviews the pathogenesis of pulmonary fibrosis in the setting of rheumatoid arthritis as well as the current and future therapeutic options.

EXPERT OPINION

Pulmonary fibrosis in the setting of RA-ILD is an example of genotype-environment interaction and involves multiple mechanisms including autoimmunity, inflammation and fibrogenesis. Despite that ILD conveys most of the exceeding mortality in RA patients, there are no official guidelines for the management of RA-ILD. Attention should be paid to potential lung toxicity of RA treatment even though some of them might help stabilise the ILD. Current standard of care is often composed of glucocorticoids that may be associated with immunosuppressive therapy. Following the approval of antifibrotic therapy for ILDs with a progressive fibrosing phenotype, current works are evaluating the benefit of such treatment in RA-ILD.

Rheumatoid Arthritis: Pathogenic Roles of Diverse Immune Cells

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease associated with synovial tissue proliferation, pannus formation, cartilage destruction, and systemic complications. Currently, advanced understandings of the pathologic mechanisms of autoreactive CD4+ T cells, B cells, macrophages, inflammatory cytokines, chemokines, and autoantibodies that cause RA have been achieved, despite the fact that much remains to be elucidated. This review provides an updated pathogenesis of RA which will unveil novel therapeutic targets.

Endogenously produced catecholamines improve the regulatory function of TLR9-activated B cells

The sympathetic nervous system (SNS) contributes to immune balance by promoting anti-inflammatory B cells. However, whether B cells possess a self-regulating mechanism by which they modulate regulatory B cell (Breg) function is not well understood. In this study, we investigated the ability of B cells to synthesize their own catecholamines upon stimulation with different B cell activators and found that expression of the enzyme tyrosine hydroxylase (TH), required to generate catecholamines, is up-regulated by Toll-like receptor (TLR)9. This TLR9-dependent expression of TH correlated with up-regulation of adrenergic receptors (ADRs), enhanced interleukin (IL)-10 production, and overexpression of the co-inhibitory ligands programmed death ligand 1 (PD-L1) and Fas ligand (FasL). Moreover, concomitant stimulation of ß1-3-ADRs together with a B cell receptor (BCR)/TLR9 stimulus clearly enhances the anti-inflammatory potential of Bregs to suppress CD4 T cells, a crucial population in the pathogenesis of autoimmune diseases, like rheumatoid arthritis (RA). Furthermore, TH up-regulation was also demonstrated in B cells during the course of collagen-induced arthritis (CIA), a mouse model for the investigation of RA. In conclusion, our data show that B cells possess an autonomous mechanism to modulate their regulatory function in an autocrine and/or paracrine manner. These findings help to better understand the function of B cells in the regulation of autoimmune diseases and the interplay of SNS.

The sympathetic nervous system produces neurotransmitters such as catecholamines which contribute to immune balance by promoting anti-inflammatory B cells. This study shows that mouse B cells can themselves synthesize, sense, and transport catecholamines, which in turn modulate regulatory B cell function in an autocrine and/or paracrine manner to suppress T cell proliferation.

Chronic obstructive pulmonary disease is characterized by reduced levels and defective suppressive function of regulatory B cells in peripheral blood

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive, persistent immune response to cigarette smoke, and it has been suggested that immune dysregulation is involved in its pathogenesis. A subset of regulatory B cells (Bregs) with high levels of the surface markers CD24 and CD38 (CD24^hiCD38^hi) has previously been shown to exert an immunosuppressive function. This study investigated the levels and activity of CD24^hiCD38^hi Bregs in stable COPD (sCOPD). Testing the peripheral blood from 65 patients with sCOPD and 39 control subjects for CD24^hiCD38^hi Breg subsets by flow cytometry showed that the patients with sCOPD had significantly lower levels of CD24^hiCD38^hi Bregs and IL-10⁺ B cells. The patients with sCOPD had lower serum interleukin-10 levels than the controls. The patients with most severe sCOPD had the lowest levels of CD24^hiCD38^hi Bregs. Spearman correlation analysis showed that the levels of CD24^hiCD38^hi Bregs in the patients with sCOPD positively correlated with serum interleukin-10 concentrations but not with levels of C-reactive protein. Compared to healthy controls, functional studies showed that Breg cells from patients with sCOPD exhibit a decreased suppressive function. We conclude that sCOPD is characterized by the exhaustion of CD24^hiCD38^hi regulatory B cells compartment. Therefore, CD24^hiCD38^hi Bregs may contribute to the pathogenesis of sCOPD.

B Cells in Rheumatoid Arthritis：Pathogenic Mechanisms and Treatment Prospects

Rheumatoid arthritis (RA) is a common, chronic, systemic autoimmune disease, and its clinical features are the proliferation of joint synovial tissue, the formation of pannus and the destruction of cartilage. The global incidence of RA is about 1%, and it is more common in women. The basic feature of RA is the body’s immune system disorders, in which autoreactive CD4⁺T cells, pathogenic B cells, M1 macrophages, inflammatory cytokines, chemokines and autoantibodies abnormally increase in the body of RA patients B cell depletion therapy has well proved the important role of B cells in the pathogenesis of RA, and the treatment of RA with B cells as a target has also been paid more and more attention. Although the inflammatory indicators in RA patients receiving B-cell depletion therapy have been significantly improved, the risk of infection and cancer has also increased, which suggests that we need to deplete pathogenic B cells instead of all B cells. However, at present we cannot distinguish between pathogenic B cells and protective B cells in RA patients. In this review, we explore fresh perspectives upon the roles of B cells in the occurrence, development and treatment of RA.

#CXCR5/CXCL13 pathway, a key driver for migration of regulatory B10 cells, is defective in patients with rheumatoid arthritis

OBJECTIVES

Chemokines (CKs) are key players of immune-cell homing and differentiation. CK receptors (CKRs) can be used to define T-cell functional subsets. We aimed to characterize the CKR profile of the regulatory B-cell subset B10+ cells and investigate the CKs involved in their migration and differentiation in healthy donors (CTLs) and patients with rheumatoid arthritis (RA).

METHODS

RNA sequencing and cytometry were used to compare CKR expression between B10+ and B10neg cells. Migration of B10+ and B10neg cells and interleukin 10 (IL-10) secretion of B cells in response to recombinant CKs or synovial fluid (SF) were assessed.

RESULTS

CXCR5 was expressed at a higher level on the B10+ cell surface as compared with other B cells (referred to as B10neg cells). In line with this, its ligand CXCL13 preferentially attracted B10+ cells over B10neg cells. Interestingly, synovial fluid from RA patients contained high levels of CXCL13 and induced strong and preferential migration of B10+ cells. Besides its role in attracting B10+ cells, CXCL13 also promoted IL-10 secretion by B cells. In RA patients, the level of CXCR5 on B cell surface was reduced. The preferential migration of RA B10+ cells toward CXCL13-rich SF was lost and CXCL13 stimulation triggered less IL-10 secretion than in healthy donors.

CONCLUSION

Our results identify that the CXCR5/CXCL13 axis is essential for B10+ cell biology but is defective in RA. Restoring the preferential migration of B10+ within the affected joints to better control inflammation may be part of therapeutic approach for RA.

The Role of Regulatory B cells in Kidney Diseases

B cells, commonly regarded as proinflammatory antibody-producing cells, are detrimental to individuals with autoimmune diseases. However, in recent years, several studies have shown that regulatory B (Breg) cells, an immunosuppressive subset of B cells, may exert protective effects against autoimmune diseases by secretion of inhibitory cytokines such as IL-10. In practice, Breg cells are identified by their production of immune-regulatory cytokines, such as IL-10, TGF-β, and IL-35, however, no specific marker or Breg cell-specific transcription factor has been identified. Multiple phenotypes of Breg cells have been found, whose functions vary according to their phenotype. This review summarizes the discovery, phenotypes, development, and function of Breg cells and highlights their potential therapeutic value in kidney diseases.

Checkpoint Receptor TIGIT Expressed on Tim-1+ B Cells Regulates Tissue Inflammation

Tim-1, a phosphatidylserine receptor expressed on B cells, induces interleukin 10 (IL-10) production by sensing apoptotic cells. Here we show that mice with B cell-specific Tim-1 deletion develop tissue inflammation in multiple organs including spontaneous paralysis with inflammation in the central nervous system (CNS). Transcriptomic analysis demonstrates that besides IL-10, Tim-1⁺ B cells also differentially express a number of co-inhibitory checkpoint receptors including TIGIT. Mice with B cell-specific TIGIT deletion develop spontaneous paralysis with CNS inflammation, but with limited inflammation in other organs. Our findings suggest that Tim-1⁺ B cells are essential for maintaining self-tolerance and restraining tissue inflammation, and that Tim-1 signaling-dependent TIGIT expression on B cells is essential for maintaining CNS-specific tolerance. A possible critical role of aryl hydrocarbon receptor (AhR) in regulating the B cell function is discussed, as we find that AhR is among the preferentially expressed transcription factors in Tim-1⁺ B cells and regulates their TIGIT and IL-10 expression.

Immunosuppressive Mechanisms of Regulatory B Cells

Regulatory B cells (Bregs) is a term that encompasses all B cells that act to suppress immune responses. Bregs contribute to the maintenance of tolerance, limiting ongoing immune responses and reestablishing immune homeostasis. The important role of Bregs in restraining the pathology associated with exacerbated inflammatory responses in autoimmunity and graft rejection has been consistently demonstrated, while more recent studies have suggested a role for this population in other immune-related conditions, such as infections, allergy, cancer, and chronic metabolic diseases. Initial studies identified IL-10 as the hallmark of Breg function; nevertheless, the past decade has seen the discovery of other molecules utilized by human and murine B cells to regulate immune responses. This new arsenal includes other anti-inflammatory cytokines such IL-35 and TGF-β, as well as cell surface proteins like CD1d and PD-L1. In this review, we examine the main suppressive mechanisms employed by these novel Breg populations. We also discuss recent evidence that helps to unravel previously unknown aspects of the phenotype, development, activation, and function of IL-10-producing Bregs, incorporating an overview on those questions that remain obscure.

Role of regulatory B cells in gastric cancer: Latest evidence and therapeutics strategies

Gastric cancer (GC) is the second most common cancer globally and kills about 700,000 people annually. Today's knowledge clearly shows a close and complicated relationship between the tumor microenvironment (TME) and the immune system. The immune system components can both stimulate tumor growth and inhibit tumor cells. However, numerous of these mechanisms are not yet fully understood. As an essential immune cell in humoral immunity, B lymphocytes can play a dual role during various pathologic states, including infections, autoimmune diseases, and cancer, depending on their phenotype and environmental signals. Inherently, B cells can inhibit tumor growth by producing antibodies as well as the presentation of tumor antigens. However, evidence suggests that a subset of these cells termed regulatory B cells (Bregs) with an inhibitory phenotype can suppress anti-tumor responses and support the tumor growth by producing anti-inflammatory cytokines and the expression of inhibitory molecules. Therefore, in this review, the role of Bregs in the microenvironment of GC and treatment strategies based on targeting this subset of B cells have been investigated.

Abatacept enhances blood regulatory B cells of rheumatoid arthritis patients to a level that associates with disease remittance

Abatacept, an inhibitor of CD28 mediated T-cell activation, has been shown to be effective in controlling inflammation during rheumatoid arthritis (RA). However, its effects on immune regulatory B and T cells (Bregs and Tregs) has not been fully explored. Thirty-one RA patients treated with abatacept for ≥ 6 months along with 31 RA patients treated with other modalities as well as 30 healthy controls were recruited. Of these 62 RA patient, 49 (79%) were females with a mean age of 54 ± 12 years and disease duration of 10 ± 6 years. The blood levels of Tregs and Bregs and their production of immunosuppressive cytokines, were determined using FACS analysis and Luminex Multiplex assay. Treatment with abatacept significantly enhanced the blood level of IL-35⁺ IL-10⁺ Bregs (P = 0.0007). Their levels were higher in the blood of remitted patients (DAS28-CRP < 2.6) compared to the unremitted ones (P = 0.0173), 6 months following abatacept treatment initiation. Moreover, abatacept treatment significantly enhanced the blood levels of LAG3⁺ conventional and unconventional Tregs of RA patients. This increase in the blood levels of Bregs and Tregs was accompanied with an elevated serum level of IL-35 and IFN-β in abatacept-treated patients. Therefore, Abatacept efficiency to achieve remittance in RA could be attributed, in part, to its ability to enhance immune regulatory cells, especially IL-135⁺ IL-10⁺ Bregs.

Circulating CD19+CD24hiCD38hi regulatory B cells as biomarkers of response to methotrexate in early rheumatoid arthritis

OBJECTIVE

The protagonism of regulatory B cells seems to vary along the course of the disease in murine models of inflammatory conditions. Decreased numbers of circulating regulatory CD19+CD24hiCD38hi transitional (cTr) B cells have been described in patients with long-standing RA, thus our objective was to examine the frequency and evolution of cTr B cells in the peripheral blood of early RA (ERA) patients.

METHODS

Freshly isolated peripheral blood mononuclear cells from 48 steroid- and DMARD-naïve ERA patients with a disease duration of <24 weeks and 48 healthy controls (HCs) were examined by flow cytometry. Co-cultures of isolated memory B cells were established with autologous T cells in the absence or presence of Tr B cells.

RESULTS

As compared with HCs, ERA patients demonstrated an increased frequency of cTr B cells. cTr B cells of ERA patients and HCs displayed an anti-inflammatory cytokine profile and were able to downregulate T cell IFN-γ and IL-21 production, together with ACPA secretion in autologous B/T cell co-cultures. Basal frequencies of cTr B cells above the median value observed in HCs were associated with a good EULAR response to MTX at 12 months [relative risk 2.91 (95% CI 1.37, 6.47)]. A significant reduction of cTr B cells was observed 12 months after initiating MTX, when the cTr B cell frequency was no longer elevated but decreased, and this was independent of the degree of clinical response or the intake of prednisone.

CONCLUSION

An increased frequency of regulatory cTr B cells is apparent in untreated ERA and the baseline cTr B cell frequency is associated with the clinical response to MTX at 12 months.

Regulatory B cells in respiratory health and diseases

B cells are critical mediators of humoral immune responses in the airways through antibody production, antigen presentation, and cytokine secretion. In addition, a subset of B cells, known as regulatory B cells (Bregs), exhibit immunosuppressive functions via diverse regulatory mechanisms. Bregs modulate immune responses via the secretion of IL‐10, IL‐35, and tumor growth factor‐β (TGF‐β), and by direct cell contact. The balance between effector and regulatory B cell functions is critical in the maintenance of immune homeostasis. The importance of Bregs in airway immune responses is emphasized by the different respiratory disorders associated with abnormalities in Breg numbers and function. In this review, we summarize the role of immunosuppressive Bregs in airway inflammatory diseases and highlight the importance of this subset in the maintenance of respiratory health. We propose that improved understanding of signals in the lung microenvironment that drive Breg differentiation can provide novel therapeutic avenues for improved management of respiratory diseases.

Innate Lymphocytes in Inflammatory Arthritis

Inflammatory arthritis (IA) refers to a group of chronic diseases, including rheumatoid arthritis (RA), psoriatic arthritis (PsA), ankylosing spondylitis (AS), and other spondyloarthritis (SpA). IA is characterized by autoimmune-mediated joint inflammation and is associated with inflammatory cytokine networks. Innate lymphocytes, including innate-like lymphocytes (ILLs) expressing T or B cell receptors and innate lymphoid cells (ILCs), play important roles in the initiation of host immune responses against self-antigens and rapidly produce large amounts of cytokines upon stimulation. TNF (Tumor Necrosis Factor)-α, IFN (Interferon)-γ, Th2-related cytokines (IL-4, IL-9, IL-10, and IL-13), IL-17A, IL-22, and GM-CSF are involved in IA and are secreted by ILLs and ILCs. In this review, we focus on the current knowledge of ILL and ILC phenotypes, cytokine production and functions in IA. A better understanding of the roles of ILLs and ILCs in IA initiation and development will ultimately provide insights into developing effective strategies for the clinical treatment of IA patients.

Interleukin-35 regulates the balance of Th17 and Treg responses during the pathogenesis of connective tissue diseases

Interleukin (IL)-35 belongs to the IL-12 cytokine family and is a heterodimer of the p35 and Epstein-Barr virus-induced gene 3 (EBI3) subunits. Functionally, IL-35 can promote the proliferation and activation of regulatory T cells (Tregs) and suppress the function of T helper 17 (Th17) cells and other inflammatory cells to inhibit immune responses. In recent years, an abnormal IL-35 expression causing a Th17/Treg imbalance has been associated with the development and progression of several connective tissue diseases (CTDs), such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic sclerosis (SSc), dermatomyositis (DM)/polymyositis (PM), and primary Sjögren's syndrome (pSS). Here, we review the role of IL-35 in regulating the balance of Th17/Treg responses in different types of CTDs and provide new insights into the role of IL-35 in these diseases.

Moderate- to high intensity aerobic and resistance exercise reduces peripheral blood regulatory cell populations in older adults with rheumatoid arthritis

Objective

Exercise can improve immune health and is beneficial for physical function in patients with rheumatoid arthritis (RA), but the immunological mechanisms are largely unknown. We evaluated the effect of moderate- to high intensity exercise with person-centred guidance on cells of the immune system, with focus on regulatory cell populations, in older adults with RA.

Methods

Older adults (≥65 years) with RA were randomized to either 20-weeks of moderate – to high intensity aerobic and resistance exercise (n = 24) or to an active control group performing home-based exercise of light intensity (n = 25). Aerobic capacity, muscle strength, DAS28 and CRP were evaluated. Blood samples were collected at baseline and after 20 weeks. The frequency of immune cells defined as adaptive regulatory populations, CD4 + Foxp3 + CD25 + CD127- T regulatory cells (Tregs) and CD19 + CD24hiCD38hi B regulatory cells (Bregs) as well as HLA-DR−/lowCD33 + CD11b + myeloid derived suppressor cells (MDSCs), were assessed using flow cytometry.

Results

After 20 weeks of moderate- to high intensity exercise, aerobic capacity and muscle strength were significantly improved but there were no significant changes in Disease Activity Score 28 (DAS28) or CRP. The frequency of Tregs and Bregs decreased significantly in the intervention group, but not in the active control group. The exercise intervention had no effect on MDSCs. The reduction in regulatory T cells in the intervention group was most pronounced in the female patients.

Conclusion

Moderate- to high intensity exercise in older adults with RA led to a decreased proportion of Tregs and Bregs, but that was not associated with increased disease activity or increased inflammation.

Trial registration

Improved Ability to Cope With Everyday Life Through a Person-centered Training Program in Elderly Patients With Rheumatoid Arthritis - PEP-walk Study, NCT02397798. Registered at ClinicalTrials.gov March 19, 2015.

Regulatory B Cells Are Decreased and Impaired in Their Function in Peripheral Maternal Blood in Pre-term Birth

Preterm birth (PTB) is defined as birth before 37 completed weeks of gestation. The causes of PTB are multiple and complex, the underlying pathophysiology being largely unknown. Interferences in the fine-tuned balance of the maternal immune system have been pointed to as one possible cause of PTB. Regulatory B cells (Breg) are part of the adaptive immune response, and recent data suggest that they may contribute to a healthy pregnancy by their regulatory/suppressive function. We investigated the frequency of Breg cells in peripheral blood of women undergoing PTB and control women immediately before giving birth via cesarean section. We detected an enhanced number of B cells, but a reduced number of Breg cells in women delivering preterm. In addition, the percentage of IL-10-producing B cells was decreased in PTB following stimulation with TLR agonists CpG or LPS, alone or combined with CD40L. This was associated with increased levels of pro-inflammatory cytokines in maternal serum. Moreover, isolated maternal B cells before delivering premature babies secreted higher level of the pro-inflammatory cytokine IL-6. No alterations in the frequency of regulatory T cells were found. Our data indicate that alterations in the number and function of Breg cells in peripheral maternal blood contribute to the immunological changes observed in preterm delivery and suggest these cells as important regulators of maternal immune responses.

CD19+CD24hiCD38hi B Cell Dysfunction in Primary Biliary Cholangitis

CD19⁺CD24^hiCD38^hi B cells are immature transitional B cells that, in normal individuals, exert suppressive effects by IL-10 production but are quantitatively altered and/or functionally impaired in individuals with various autoimmune diseases. Primary biliary cholangitis (PBC), an autoimmune disease, clinically presents as chronic cholestasis and nonsuppurative destructive cholangitis. A role for CD19⁺CD24^hiCD38^hi B cells in PBC is unknown. This study investigated the frequency and functional variation of circulating CD19⁺CD24^hiCD38^hi B cells in PBC patients. Flow cytometry was employed to quantify the percentage of CD19⁺CD24^hiCD38^hi B cells in peripheral blood samples. Correlations between CD19⁺CD24^hiCD38^hi B cells and routine laboratory parameters were assessed. Levels of IL-10, TNF-α, IL-6 and IL-12, and Tim-1 in CD19⁺CD24^hiCD38^hi B cells from PBC patients were analyzed. The effect of CD19⁺CD24^hiCD38^hi B cells on CD4⁺T cell differentiation was evaluated. The percentage of CD19⁺CD24^hiCD38^hi B cells in PBC patients was significantly higher than in healthy controls and was positively correlated with liver cholestasis. After activation by anti-B cell receptor and CpG, the production of IL-10 was decreased and the production of IL-6 and IL-12 was increased in CD19⁺CD24^hiCD38^hi B cells from PBC patients. Moreover, Tim-1 levels were significantly downregulated in CD19⁺CD24^hiCD38^hi B cells from PBC patients. Coculture showed that PBC-derived CD19⁺CD24^hiCD38^hi B cells were less capable of CD4⁺T cell inhibition, but promoted Th1 cell differentiation. In conclusion, PBC patients have expanded percentages, but impaired CD19⁺CD24^hiCD38^hi B cells, which correlate with disease damage. In PBC patients, this B cell subset has a skewed proinflammatory cytokine profile and a decreased capacity to suppress immune function, which may contribute to the pathogenesis of PBC.

Potential role of regulatory B cells in immunological diseases

Regulatory B cells (Bregs) are immune-modulating cells that affect the immune system by producing cytokines or cellular interactions. These cells have immunomodulatory effects on the immune system by cytokine production. The abnormalities in Bregs could be involved in various disorders such as autoimmunity, chronic infectious disease, malignancies, allergies, and primary immunodeficiencies are immune-related scenarios. Ongoing investigation could disclose the biology and the exact phenotype of these cells and also the assigned mechanisms of action of each subset, as a result, potential therapeutic strategies for treating immune-related anomalies. In this review, we collect the findings of human and mouse Bregs and the therapeutic efforts to change the pathogenicity of these cells in diverse disease.

Regulatory B cells: New players in inflammatory and autoimmune rheumatic diseases

OBJECTIVE

Regulatory B cells (Bregs) are a new subset of B cells with immunoregulatory functions, mainly through IL-10 production. Bregs suppress inflammatory Th1 and Th17 differentiation and induce Tregs suppressing autoimmune diseases. The aim of the study was to review the literature related to Bregs in autoimmune rheumatic diseases (ARDs).

METHODS

A literature review of publications in PUBMED published in English was performed using the relevant combinations of terms.

RESULTS

All relevant publications are discussed. Overall, recent studies in rheumatic diseases found Bregs to be decreased in ANCA-associated vasculitides (AAV) and in systemic sclerosis (SSc), particularly in SSc-associated lung fibrosis. In AAV Bregs levels are negatively correlated with autoantibody levels whereas in SSc this association is less clear but there is an inverse association with Th1 and Th17 cells. In rheumatoid arthritis (RA), Bregs were decreased, particularly in RA-associated lung fibrosis. In psoriatic arthritis IL-10 + Bregs are decreased and inversely associated with Th1 and Th17 cells. In systemic lupus erythematosus (SLE), the role of Bregs is unclear. In experimental diseases, when Bregs were expanded ex-vivo, they ameliorated established disease.

CONCLUSION

Bregs appear to be a new player in the pathogenesis of ARDs, and may offer a new strategy for therapeutic intervention.

Effect of binding immunoglobulin protein on induction of regulatory B cells with killer phenotype during inflammation and disease

Immune responses result from different immune cells acting in synergy to successfully fight infections. This requires a high degree of regulation to prevent excessive production of inflammatory products leading to other disease forms. Regulatory B cells are classified based on surface immunoglobulin expression. These cells are reported to resolve inflammation during chronic or autoimmune diseases. However, during chronic inflammation, their frequencies have been shown to be affected, and they can be induced by exposure to extracellular binding immunoglobulin protein (BiP). This review focuses on the effects on immune cells by extracellular or secreted BiP during various chronic inflammatory responses. For example, cell stress associated with Mycobacterium tuberculosis infection leads to accumulation of unfolded proteins that subsequently activate BiP and its three signal transducers intracellularly. Furthermore, BiP can be translocated from the endoplasmic reticulum to the extracellular environment where it binds immune cells as an autoantigen and leads to functional changes.

Immune responses during tuberculosis disease require balanced cell interactions. These include antigen-presenting cells, effector cells and regulatory cells. B lymphocytes can mediate regulatory function during chronic diseases and lead to better disease outcome. These specialized cells mediate this function through both surface and soluble protein expression. Their development can be facilitated by different stimuli including binding immunoglobulin protein. This protein resides in the endoplasmic reticulum where it functions in proper protein folding; however, it can escape this location to the extracellular phase, where it affects immune cell function leading to development of regulatory traits on B cells.

IgM+CD27+ B cells possessed regulatory function and represented the main source of B cell-derived IL-10 in the synovial fluid of osteoarthritis patients

Synovial inflammation is observed in patients with osteoathritis (OA) and likely contributed to its exacerbation. Regulatory B (Breg) cells are shown to suppress inflammation in various diseases, including rheumatoid arthritis (RA). To examine whether Breg cells also participated in OA, we examined the synovial fluid from OA patients, and compared with that in RA patients. In OA synovial fluid, IL-10-producing B cells were present directly ex vivo and were increased upon stimulation, indicating that B cells were a source of IL-10 directly at the affected site of OA patients. Interestingly, the frequency of IL-10⁺ cells in synovial B cells was higher in OA patients than in RA patients, but the total number of IL-10⁺ B cells in OA was lower than that in RA, suggesting that OA patients presented lower B cell infiltration than RA patients. Phenotypical analysis demonstrated that the IL-10⁺ B cells were IgM⁺ and CD27⁺, but not CD24^hi or CD38^hi. To allow functional analysis of IgM⁺CD27⁺ B cells, the IgM⁺CD27⁺ B cells in the blood of OA patients were examined. These blood IgM⁺CD27⁺ B cells expressed more IL-10, but less CD80 and CD86 than non-IgM⁺CD27⁺ B cells. Blood IgM⁺CD27⁺ B cells suppressed the proliferation and IFN-γ expression of autologous T cells, and this effect could be reverted if IL-10 was inhibited. Furthermore, we found that patients with more severe OA presented lower levels of IL-10⁺ B cells in the synovial fluid. Together, our study described an IgM⁺CD27⁺ B cell subset in OA patients, which represented the major IL-10-secreting B cell type in the synovial fluid of OA patients and possessed regulatory function.

PD-L1+ Regulatory B Cells Are Significantly Decreased in Rheumatoid Arthritis Patients and Increase After Successful Treatment

Background: B cells play an important role in the development and maintenance of rheumatoid arthritis (RA). Although IL-10-producing B cells represent a major subset of regulatory B cells (Bregs) able to suppress autoimmune and inflammatory responses, recent reports showed that B cell-mediated immune suppression may also occur independent of IL-10. For instance, B cells can modulate T cell immune responses through the expression of regulatory molecules such as PD-L1. So far, PD-L1-expressing B cells have not been analyzed in RA patients. Objective: To analyze the frequency of PD-L1-expressing B cells in the peripheral blood of RA patients compared to healthy controls (HC) matched for sex and age, their function on T cell response and their changes in response to therapy. Methods: Fresh peripheral blood B cells from RA patients and HC were characterized by flow cytometry and their functionality assessed in a co-culture system with autologous T cells. Results: The frequencies of CD19⁺PD-L1⁺ B cells, CD24^hiCD38^-PD-L1⁺ and CD24^hiCD38^hiPD-L1⁺ B cells were significantly lower in untreated RA patients than in HC. In a follow-up study, the frequencies of PD-L1⁺ B cells (CD19⁺PD-L1⁺ B cells, CD24^hiCD38^-PD-L1⁺ and CD24^hiCD38^hiPD-L1⁺ B cells) increased significantly after treatment in good responder patients, although the frequency of total CD24^hiCD38^hi B cells decreased. CD19⁺ B cells from untreated RA patients and HC upregulated PD-L1 expression similarly upon stimulation with CpG plus IL-2 and were able to suppress, in vitro, CD8⁺ T cell proliferation and cytokine production in a PD-L1-dependent manner. Conclusions: Our results show that PD-L1⁺ B cells exhibiting T cell suppressive capacity are significantly decreased in untreated RA patients but increase in response to successful treatment. PD-L1 expression on B cells from RA patients can be modulated in vitro and PD-L1⁺ B cells could thus provide new perspectives for future treatment strategies.

Could Lymphocyte Profiling be Useful to Diagnose Systemic Autoimmune Diseases?

Considering the implications of B, T, and natural killer (NK) cells in the pathophysiology of systemic autoimmune diseases, the assessment of their distribution in the blood could be helpful for physicians in the complex process of determining a precise diagnosis. In primary Sjögren's syndrome, transitional and active naive B cells are increased and memory B cells are decreased compared to healthy controls and other systemic diseases. However, their utility to improve the accuracy of classification criteria has not been proven. In early untreated rheumatoid arthritis, proportions of regulatory T cells are constantly reduced, but other patterns are difficult to determine given the heterogeneity of published studies. In systemic lupus erythematosus, the lack of studies using large cohorts of patients and the diversity of the possible pathological mechanisms involved are also important impediments. Nevertheless, transitional B cell and plasma cell proportions are increased in most of the studies, the CD4/CD8 ratio is decreased, and the number of NK cells is reduced. Despite the low number of studies, anomalies of lymphocyte subset distribution was also described in ANCA-associated vasculitis, systemic scleroderma, and myositis. For now, flow cytometric analysis of lymphocyte subsets has focused mainly on specific subpopulations and is more useful for basic and translational research than for diagnostics in clinical practice. However, new modern methods such as mass cytometry and bioinformatics analyses may offer the possibility to simultaneously account for the relative proportions of multiple lymphocyte subsets and define a global profile in homogeneous groups of patients. The years to come will certainly incorporate such global lymphocyte profiling in reclassification of systemic autoimmune diseases.

Frequency of CD19+CD24hiCD38hi regulatory B cells is decreased in peripheral blood and synovial fluid of patients with juvenile idiopathic arthritis: a preliminary study

BACKGROUND

To understand the relationship between regulatory B cells (Bregs) and juvenile idiopathic arthritis (JIA), we analyzed the percentages of Bregs and their function in peripheral blood (PB) and synovial fluid (SF) of JIA patients.

METHODS

Twenty-one JIA patients and 11 children with growing pain but without known rheumatic diseases as controls were included. The B cell phenotype and intracellular production of IL-10 of Bregs were assessed by flow cytometry. Mononuclear cells from PB and SF were stimulated to produce IL-10 in vitro for the identification of IL-10- producing regulatory B cells.

RESULTS

The percentage of CD24^hiCD38^hi Bregs in the PB of JIA patients was significantly decreased compared to that in controls, and it was even lower in the SF of JIA patients compared to that in the PB. CD24^hiCD38^hi Bregs frequency was significantly lower in the PB of RF-positive patients than in RF-negative patients. Frequency of IL-10-producing regulatory B cells (B10 cells) was significantly lower in active JIA patients than that in inactive patients.

CONCLUSIONS

The inability of the host to produce enough regulatory B cells in PB and especially in SF of JIA patients may contribute to the disease, especially the local inflammation.

Cellular expression of CD markers in immune thrombocytopenic purpura: implications for prognosis

Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder associated with platelet destruction. Abnormalities in frequency and function of different immune cells can play a crucial role in this disease. The aim of this study was to evaluate the prognostic value of CD markers' expressions by immune cells in ITP. Peripheral blood samples were collected from 25 ITP patients before and after treatment. The expression of CD markers was evaluated by flow cytometry technique. The expression of CD38 and CD56 was significantly lower before treatment than after it (p = 0.025 and p = 0.036, respectively). Furthermore, a positive correlation was found between CD38 expression with platelet count before (r = 0.496, p = 0.012) and after treatment (r = 0.404, p = 0.045). No significant relationship was found between this marker and platelet count while CD4 expression was higher before treatment than after it (p = 0.002). In conclusion, CD38 may have independent prognostic value in ITP and we suggest that it can be a prognostic marker for this disease.

Deficiency of IL-1 receptor antagonist suppresses IL-10-producing B cells in autoimmune arthritis in an IL-17/Th17-dependent manner

Rheumatoid arthritis (RA) is a systemic autoimmune disease with CD4⁺ T cell infiltration and hyperplasia of synovial tissues leading to progressive destruction of articular cartilage. In addition to the central role of T cells in the pathogenesis of RA, recent reports have suggested that B cells also contribute to RA. To explore the effects of interleukin (IL)-17 on B cell development and response in excess IL-1 signaling, we generated IL-17 and IL-1 receptor antagonist (IL-1Ra) double-deficient mice via backcrossing IL-17 knockout (KO) and IL-1RaKO mice. We studied the effect of IL-17 deficiency on antibody-producing B cells and regulatory B cells in IL-1RaKO mice. Excess IL-1 signal increased the frequency of B220⁺ IgG⁺ cells and plasma cells. It also promoted the production of immunoglobulins in vitro. Moreover, IL-17 deficiency significantly enhanced the frequency of regulatory IL-10-producing regulatory B cells in IL-1RaKO mice. IL-17 deficiency ameliorated disease symptoms of inflammatory arthritis in IL-1RaKO mice by suppressing the frequency of plasma cells and antibody production while enhancing the frequency of IL-10-producing B cells. These findings suggest that IL-17 can trigger an inflammatory immune reaction by activating antibody-producing B cells while suppressing immune regulatory B cells in RA.

B Lymphocytes in Rheumatoid Arthritis and the Effects of Anti-TNF-α Agents on B Lymphocytes: A Review of the Literature

PURPOSE

The aim of this article was to review published research related to B lymphocytes in rheumatoid arthritis, their role in the pathogenesis of the disease, the effects of tumor necrosis factor (TNF)-α inhibitors on B lymphocytes, the risk for infection, and responses to vaccines.

METHODS

A PubMed search was conducted to review recent advances related to B lymphocytes and the effects of anti-TNF-α on B lymphocytes in rheumatoid arthritis.

FINDINGS

B lymphocytes play an important role in the pathogenesis of rheumatoid arthritis. In this review, we summarize the major mechanisms by which B lymphocytes play a pathologic role in the development and propagation of the disease, as B lymphocytes are recruited to the synovial fluid, where they contribute to local inflammation through the secretion of pro-inflammatory mediators (cytokines, chemokines, micro-RNAs) and present antigens to T cells. We discuss the effects of TNF-α, either direct or indirect, on B lymphocytes expressing receptors for this cytokine. We also show that total B-cell numbers have been reported to be reduced in the blood of patients with rheumatoid arthritis versus healthy controls, but are significantly increased up to normal levels in patients undergoing anti-TNF-α therapy. As for B-cell subsets, controversial results have been reported, with studies showing decreased frequencies of total memory B cells (and memory subsets) and others showing no differences in patients versus healthy controls. Studies investigating the effects of anti-TNF-α therapy have also given controversial results, with therapy found to increase (or not) the frequency of memory B lymphocytes, in patients with rheumatoid arthritis versus healthy controls. Those highly variable results could have been due to differences in patient characteristics and limited numbers of subjects. Finally, we summarize the effects of blocking TNF-α with anti-TNF-α agents on possible infections that patients with rheumatoid arthritis may contract, as well as on responses to vaccination.

IMPLICATIONS

B lymphocytes play a significant role in the pathogenesis of rheumatoid arthritis, and B cell-depletion therapy has a major effect on the course of the disease. The advances in treatment of rheumatoid arthritis include the development of targeted therapies. Anti-TNF-α therapies are widely used despite potentially serious adverse events. The data on the effects of anti-TNF-α therapies on B lymphocytes are limited and conflicting. There is a need for larger studies to better understand the effects of newly discovered therapies on the different cells of the immune system.

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.

Regulatory B cells in autoimmune rheumatic diseases

Background:

Regulatory B cells (regulatory B cells, Breg cells) in recent years have been shown to be important immunoregulatory factors.

Aim:

To review the role of Breg cells in autoimmune rheumatic diseases.

Methods:

This descriptional review was carried out after research on PubMed using the keywords “Bregs and rheumatoid arthritis”, “systemic lupus erythematosus”, “Sjögren’s syndrome”, “systemic sclerosis”, “vasculitis”, and “dermatomyositis”.

Results:

Breg cells have an inhibitory effect on pro-inflammatory Th1 and Th17 cells and prevent the development of autoimmune diseases. Breg cells mediate their effects through interleukin-10 (IL-10, IL-10+Breg cells), but recently other Breg cells have been recognized that mediate their effects through IL-35 (IL-35+Breg cells), or through transforming growth factor-β (TGFβ, TGFβ+Breg cells). In experimental models of autoimmune diseases, Breg cells are decreased, and when expanded ex vivo and re-infused back into animals, they ameliorate disease. In humans, IL-10+Breg cells are decreased in active autoimmune diseases, such as rheumatoid arthritis, ANCA-associated vasculitis, and systemic sclerosis, and may increase to normal levels in disease remission.

Conclusions:

The deficiency of IL-10+Breg cells during active autoimmune rheumatic disease suggests that Breg cells may be used as biomarkers and be a possible therapeutic target in these diseases.

Intra-Articular Injection of Human Synovial Membrane-Derived Mesenchymal Stem Cells in Murine Collagen-Induced Arthritis: Assessment of Immunomodulatory Capacity In Vivo

The aim of this study was to evaluate the efficacy of human synovial membrane-derived MSCs (SM-MSCs) in murine collagen-induced arthritis (CIA). Male mice (age 7–9 weeks) were injected intra-articularly with SM-MSCs obtained from patients with osteoarthritis, on days 28, 32, and 38 after bovine type II collagen immunization. The efficacy of SM-MSCs in CIA was evaluated clinically and histologically. Cytokine profile analyses were performed by real-time polymerase chain reaction and multiplex analyses. Splenic helper T (Th) cell and regulatory B cell subsets were analyzed by flow cytometry. Intra-articular SM-MSC injection ameliorated the clinical and histological severity of arthritis. Decrease in tumor necrosis factor-α, interferon-γ, and interleukin- (IL-) 17A and increase in IL-10 production were observed after SM-MSC treatment. Flow cytometry showed that Th1 and Th17 cells decreased, whereas Th2, regulatory T (Treg), and PD-1⁺CXCR5⁺FoxP3⁺ follicular Treg cells increased in the spleens of SM-MSC-treated mice. Regulatory B cell analysis showed that CD21^hiCD23^hi transitional 2 cells, CD23^lowCD21^hi marginal zone cells, and CD19⁺CD5⁺CD1d⁺IL-10⁺ regulatory B cells increased following SM-MSC treatment. Our results demonstrated that SM-MSCs injected in inflamed joints in CIA had a therapeutic effect and could prevent arthritis development and suppress immune responses via immunoregulatory cell expansion.

Human regulatory B cells in health and disease: therapeutic potential

Regulatory B cells (Bregs) modulate immune responses predominantly, although not exclusively, via the release of IL-10. The importance of human Bregs in the maintenance of immune homeostasis comes from a variety of immune-related pathologies, such as autoimmune diseases, cancers, and chronic infections that are often associated with abnormalities in Breg numbers or function. A continuous effort toward understanding Breg biology in healthy individuals will provide new opportunities to develop Breg immunotherapy that could prove beneficial in treating various immune-mediated pathologies. In this Review, we discuss findings regarding human Bregs, including their mechanisms of suppression and role in different disease settings. We also propose several therapeutic strategies targeting Bregs for better management of immune disorders.

Th17 and CD24hiCD27+ regulatory B lymphocytes are biomarkers of response to biologics in rheumatoid arthritis

Background

The aim was to describe the regulatory B and T cells (Breg and Treg) and T helper 17 (Th17) lymphocytes before and under treatment with biologic drugs, and to assess their potential predictive value as biomarkers of response in rheumatoid arthritis (RA).

Methods

This was a non-randomised, single-centre, prospective study. Patients with active RA (American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) 2010) who required the initiation or switch to any biologic drug except rituximab were included. The main judgement criterion was the frequency and absolute number of CD24^hiCD27⁺ Breg and CD24^hiCD38^hi T2/Breg cells, CD25^hiCD127^low Treg and CD45RA⁻CD161⁺CCR6⁺ Th17 cells measured at inclusion in both patients and controls, and after 1, 3 and 6 months of treatment (M1, M3 and M6) in patients with RA, and compared with the M6 response to treatment (EULAR response and Disease Activity Score in 28 joints (DAS28) remission).

Results

Thirty-one patients with RA and 17 controls were included. There was a reduction in T2/Breg frequency at M0 in patients (p < 0.001) and absolute numbers (p = 0.014) and in immunopositive vs. immunonegative RA (p = 0.016). DAS28 remission at M6 was associated with increased frequency of Treg (p = 0.01). A higher level of CD24^hiCD27⁺ Breg at baseline was associated with DAS28 remission at M6 (p = 0.04) and a good EULAR response at M6 for abatacept-treated patients (p = 0.01). A lower M0 level of Th17 was associated with a good EULAR response at M6 (p = 0.007), notably under anti-cytokine drugs (p = 0.048).

Conclusions

Altogether, these data, although preliminary, suggest that phenotyping of T and B cells has potential value for the stratification of biologic drugs, notably with respect to choosing between abatacept and anti-cytokine blockade.

Tolerance in Kidney Transplantation: What Is on the B Side?

Regulatory B cells (Breg) are in the spotlight for their role in immune homeostasis maintenance and tolerance achievement as in the last years the correlation with functional and increased Breg numbers in autoimmune diseases and transplantation has been extensively proven. Their study is, however, in its infancy with still little knowledge and consensus on their origin, phenotype, and mechanism of action. All this hampers the pursuit of an effective Breg induction method for therapeutic purposes. In this review we aim to summarize the studies on human Breg and their implication in kidney transplantation and to further discuss the issues surrounding therapeutic applications of this cell subset.

Effect of Tripterygium Wilfordii Polyglycoside on Experimental Prostatitis Caused by Ureaplasma Urealyticum in Rats

Background

Prostatitis is a common and refractory urological disease with complicated etiology. Ureaplasma urealyticum (UU) has a close relationship with human urinary tract infection that can induce nonbacterial prostatitis. Tripterygium wilfordii polyglycoside (TWP) is a non-steroidal immune inhibitor that causes significant immune suppression and anti-inflammatory effects. Its role in prostatitis caused by UU has not yet been established. The aim of this study was to investigate the effect of TWP on UU-infected prostatitis in a rat model.

Material/Methods

UU-infected prostatitis SD model rats were randomly divided into 2 groups: the prostatitis group (model group) and the TWP treatment group (treatment group). At 7 days after treatment, prostate weight, leucocyte count, lecithin corpuscles, UU infection rate, and UU microbe count were compared between the 2 groups. Serum inflammatory cytokines TNF-α was determined by ELISA, and ICAM-1 and NF-κB expression were detected.

Results

UU infection rate was 80% after modeling. The rat prostate weight and leucocyte count in the model group increased significantly, while lecithin corpuscles decreased. Compared with controls, inflammatory factor TNF-α, ICAM-1, and NF-κB expression were obviously higher (P<0.05). TWP markedly reduced prostate weight and leucocyte count, increased lecithin corpuscles, and decreased UU microbe count and TNF-α, ICAM-1, and NF-κB expression (P<0.05).

Conclusions

TWP can inhibit expression of inflammatory factors and may be useful in treating UU-infected prostatitis through reducing UU infection rate.