Alterations on peripheral blood B-cell subpopulations in very early arthritis patients

Fibroblast-like synoviocytes preferentially induce terminal differentiation of IgD+ memory B cells instead of naïve B cells

Rheumatoid arthritis (RA) is a systemic autoimmune disease driven by highly active autoantibody-producing B cells. Activation of B cells is maintained within ectopic germinal centres found in affected joints. Fibroblast-like synoviocytes (FLS) present in inflamed joints support B-cell survival, activation, and differentiation. CD27+ memory B cells and naive B cells show very different responses to activation, particularly by CD40 ligand (CD40L). We show that FLS-dependent activation of human B cells is dependent on interleukin-6 (IL-6) and CD40L. FLS have been shown to activate both naive and memory B cells. Whether the activating potential of FLS is different for naive and memory B cells has not been investigated. Our results suggest that FLS-induced activation of B cells is dependent on IL-6 and CD40L. While FLS are able to induce plasma cell differentiation, isotype switching, and antibody production in memory B cells, the ability of FLS to activate naive B cells is significantly lower.

B cell dysregulation and depletion therapy in primary membranous nephropathy: Prospects and potential challenges

B cells are crucial to the humoral immune response, originating in the bone marrow and maturing in the spleen and lymph nodes. They primarily function to protect against a wide range of infections through the secretion of antibodies. The role of B cells in primary membranous nephropathy (PMN) has gained significant attention, especially following the discovery of various autoantibodies that target podocyte antigens and the observed positive outcomes from B cell depletion therapy. Increasing evidence points to the presence of abnormal B cell subsets and functions in MN. B cells have varied roles during the different stages of disease onset, progression, and relapse. Initially, B cells facilitate self-antigen presentation, activate effector T cells, and initiate cellular immunity. Subsequently, the disruption of both central and peripheral immune tolerance results in the emergence of autoreactive B cells, with strong germinal center responses as a major source of MN autoantibodies. Additionally, critical B cell subsets, including Bregs, memory B cells, and plasma cells, play roles in the immune dysregulation observed in MN, assisting in predicting disease recurrence and guiding management strategies for MN. This review offers a detailed overview of research advancements on B cells and elucidates their pathological roles in MN.

Journey through discovery of 75 years glucocorticoids: evolution of our knowledge of glucocorticoid receptor mechanisms in rheumatic diseases

For three-quarters of a century, glucocorticoids (GCs) have been used to treat rheumatic and autoimmune diseases. Over these 75 years, our understanding of GCs binding to nuclear receptors, mainly the glucocorticoid receptor (GR) and their molecular mechanisms has changed dramatically. Initially, in the late 1950s, GCs were considered important regulators of energy metabolism. By the 1970s/1980s, they were characterised as ligands for hormone-inducible transcription factors that regulate many aspects of cell biology and physiology. More recently, their impact on cellular metabolism has been rediscovered. Our understanding of cell-type-specific GC actions and the crosstalk between various immune and stromal cells in arthritis models has evolved by investigating conditional GR mutant mice using the Cre/LoxP system. A major achievement in studying the complex, cell-type-specific interplay is the recent advent of omics technologies at single-cell resolution, which will provide further unprecedented insights into the cell types and factors mediating GC responses. Alongside gene-encoded factors, anti-inflammatory metabolites that participate in resolving inflammation by GCs during arthritis are just being uncovered. The translation of this knowledge into therapeutic concepts will help tackle inflammatory diseases and reduce side effects. In this review, we describe major milestones in preclinical research that led to our current understanding of GC and GR action 75 years after the first use of GCs in arthritis.

JAK inhibitors attenuate hyperactivation of nonswitched memory B cells in rheumatoid arthritis patients in remission

OBJECTIVE

To investigate the distribution and activation of B-cell subpopulations in rheumatoid arthritis (RA) patients treated with Janus kinase inhibitors (JAKis) and to analyze their correlation with disease remission.

METHODS

Peripheral blood samples were collected from 23 adult healthy controls and 58 RA patients, 31 of whom were treated with JAKis and assessed during a 24-month follow-up. The number of peripheral B-cell subpopulations (including naive B cells, nonswitched memory B (NSMB) cells, switched memory B cells, and double-negative B cells), their activation, and phosphorylation of SYK and AKT upon B-cell receptor (BCR) stimulation in each population were analyzed by flow cytometry.

RESULTS

Compared with that in healthy controls, the frequency of NSMB cells was significantly lower in new-onset untreated RA patients. However, expression of CD40, CD80, CD95, CD21low and pAKT significantly increased in these NSMB cells. Additionally, the number of NSMB cells correlated negatively with DAS28-ESR and IgG and IgA levels in these patients; expression of CD80, CD95 and CD21low on NSMB cells correlated positively with DAS28-ESR and IgG and IgA levels. After treatment with JAKis, the serum IgG concentration significantly decreased in RA patients in remission, but CD40, CD95 and pAKT levels in NSMB cells significantly decreased.

CONCLUSION

RA patients present different B-cell subpopulations, in which the frequency of NSMB cells is negatively associated with disease activity. However, treatment with JAKis can inhibit activation of NSMB cells, restore the balance of kinase phosphorylation, and facilitate disease remission in RA patients.

Cartilage destruction in early rheumatoid arthritis patients correlates with CD21-/low double-negative B cells

BACKGROUND

Involvement of B cells in the pathogenesis of rheumatoid arthritis (RA) is supported by the presence of disease-specific autoantibodies and the efficacy of treatment directed against B cells. B cells that express low levels of or lack the B cell receptor (BCR) co-receptor CD21, CD21-/low B cells, have been linked to autoimmune diseases, including RA. In this study, we characterized the CD21+ and CD21-/low B cell subsets in newly diagnosed, early RA (eRA) patients and investigated whether any of the B cell subsets were associated with autoantibody status, disease activity and/or joint destruction.

METHODS

Seventy-six eRA patients and 28 age- and sex-matched healthy donors were recruited. Multiple clinical parameters were assessed, including disease activity and radiographic joint destruction. B cell subsets were analysed in peripheral blood (PB) and synovial fluid (SF) using flow cytometry.

RESULTS

Compared to healthy donors, the eRA patients displayed an elevated frequency of naïve CD21+ B cells in PB. Amongst memory B cells, eRA patients had lower frequencies of the CD21+CD27+ subsets and CD21-/low CD27+IgD+ subset. The only B cell subset found to associate with clinical factors was the CD21-/low double-negative (DN, CD27-IgD-) cell population, linked with the joint space narrowing score, i.e. cartilage destruction. Moreover, in SF from patients with established RA, the CD21-/low DN B cells were expanded and these cells expressed receptor activator of the nuclear factor κB ligand (RANKL).

CONCLUSIONS

Cartilage destruction in eRA patients was associated with an expanded proportion of CD21-/low DN B cells in PB. The subset was also expanded in SF from established RA patients and expressed RANKL. Taken together, our results suggest a role for CD21-/low DN in RA pathogenesis.

Aberrant B-cell activation and B-cell subpopulations in rheumatoid arthritis: analysis by clinical activity, autoantibody seropositivity, and treatment

Few studies analyze the role of B-cell subpopulations in rheumatoid arthritis (RA) pathophysiology. Therefore, this study aimed to analyze the differences in B-cell subpopulations and B-cell activation according to disease activity, RA subtype, and absence of disease-modifying antirheumatic drugs (DMARDs) therapy. These subgroups were compared with control subjects (CS). One hundred and thirty-nine subjects were included, of which 114 were RA patients, and 25 were controls. Patients were divided into 99 with seropositive RA, 6 with seronegative RA, and 9 without DMARDs. The patients with seropositive RA were subclassified based on the DAS28 index. A seven-color multicolor flow cytometry panel was used to identify B-cell immunophenotypes and cell activation markers. There were no changes in total B-cell frequencies between RA patients and controls. However, a lower frequency of memory B cells and pre-plasmablasts was observed in seropositive RA compared to controls (P < 0.0001; P = 0.0043, respectively). In contrast, a higher frequency of mature B cells was observed in RA than in controls (P = 0.0002). Among patients with RA, those with moderate activity had a higher percentage of B cells (P = 0.0021). The CD69+ marker was increased (P < 0.0001) in RA compared to controls, while the CD40+ frequency was decreased in patients (P < 0.0001). Transitional, naïve, and double-negative B-cell subpopulations were higher in seronegative RA than in seropositive (P < 0.01). In conclusion, in seropositive and seronegative RA patients, there are alterations in B-cell activation and B-cell subpopulations, independently of clinical activity and DMARDs therapy.

Children with extended oligoarticular and polyarticular juvenile idiopathic arthritis have alterations in B and T follicular cell subsets in peripheral blood and a cytokine profile sustaining B cell activation

OBJECTIVES

The main goal of this study was to characterise the frequency and phenotype of B, T follicular helper (Tfh) and T follicular regulatory (Tfr) cells in peripheral blood and the cytokine environment present in circulation in children with extended oligoarticular juvenile idiopathic arthritis (extended oligo JIA) and polyarticular JIA (poly JIA) when compared with healthy controls, children with persistent oligoarticular JIA (persistent oligo JIA) and adult JIA patients.

METHODS

Blood samples were collected from 105 JIA patients (children and adults) and 50 age-matched healthy individuals. The frequency and phenotype of B, Tfh and Tfr cells were evaluated by flow cytometry. Serum levels of APRIL, BAFF, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-17A, IL-21, IL-22, IFN-γ, PD-1, PD-L1, sCD40L, CXCL13 and TNF were measured by multiplex bead-based immunoassay and/or ELISA in all groups included.

RESULTS

The frequency of B, Tfh and Tfr cells was similar between JIA patients and controls. Children with extended oligo JIA and poly JIA, but not persistent oligo JIA, had significantly lower frequencies of plasmablasts, regulatory T cells and higher levels of Th17-like Tfh cells in circulation when compared with controls. Furthermore, APRIL, BAFF, IL-6 and IL-17A serum levels were significantly higher in paediatric extended oligo JIA and poly JIA patients when compared with controls. These immunological alterations were not found in adult JIA patients in comparison to controls.

CONCLUSIONS

Our results suggest a potential role and/or activation profile of B and Th17-like Tfh cells in the pathogenesis of extended oligo JIA and poly JIA, but not persistent oligo JIA.

Disease mechanisms in preclinical rheumatoid arthritis: A narrative review

In the last decades, the concept of preclinical rheumatoid arthritis (RA) has become established. In fact, the discovery that disease mechanisms start years before the onset of clinical RA has been one of the major recent insights in the understanding of RA pathogenesis. In accordance with the complex nature of the disease, preclinical events extend over several sequential phases. In a genetically predisposed host, environmental factors will further increase susceptibility for incident RA. In the initial steps of preclinical disease, immune disturbance mechanisms take place outside the joint compartment, namely in mucosal surfaces, such as the lung, gums or gut. Herein, the persistent immunologic response to altered antigens will lead to breach of tolerance and trigger autoimmunity. In a second phase, the immune response matures and is amplified at a systemic level, with epitope spreading and widening of the autoantibody repertoire. Finally, the synovial and bone compartment are targeted by specific autoantibodies against modified antigens, initiating a local inflammatory response that will eventually culminate in clinically evident synovitis. In this review, we discuss the elaborate disease mechanisms in place during preclinical RA, providing a broad perspective in the light of current evidence.

B Cells on the Stage of Inflammation in Juvenile Idiopathic Arthritis: Leading or Supporting Actors in Disease Pathogenesis?

Juvenile idiopathic arthritis (JIA) is a term that collectively refers to a group of chronic childhood arthritides, which together constitute the most common rheumatic condition in children. The International League of Associations for Rheumatology (ILAR) criteria define seven categories of JIA: oligoarticular, polyarticular rheumatoid factor (RF) negative (RF-), polyarticular RF positive (RF+), systemic, enthesitis-related arthritis, psoriatic arthritis, and undifferentiated arthritis. The ILAR classification includes persistent and extended oligoarthritis as subcategories of oligoarticular JIA, but not as distinct categories. JIA is characterized by a chronic inflammatory process affecting the synovia that begins before the age of 16 and persists at least 6 weeks. If not treated, JIA can cause significant disability and loss of quality of life. Treatment of JIA is adjusted according to the severity of the disease as combinations of non-steroidal anti-inflammatory drugs (NSAIDs), synthetic and/ or biological disease modifying anti-rheumatic drugs (DMARDs). Although the disease etiology is unknown, disturbances in innate and adaptive immune responses have been implicated in JIA development. B cells may have important roles in JIA pathogenesis through autoantibody production, antigen presentation, cytokine release and/ or T cell activation. The study of B cells has not been extensively explored in JIA, but evidence from the literature suggests that B cells might have indeed a relevant role in JIA pathophysiology. The detection of autoantibodies such as antinuclear antibodies (ANA), RF and anti-citrullinated protein antibodies (ACPA) in JIA patients supports a breakdown in B cell tolerance. Furthermore, alterations in B cell subpopulations have been documented in peripheral blood and synovial fluid from JIA patients. In fact, altered B cell homeostasis, B cell differentiation and B cell hyperactivity have been described in JIA. Of note, B cell depletion therapy with rituximab has been shown to be an effective and well-tolerated treatment in children with JIA, which further supports B cell intervention in disease development.

B cell subset composition segments clinically and serologically distinct groups in chronic cutaneous lupus erythematosus

OBJECTIVE

While the contribution of B-cells to SLE is well established, its role in chronic cutaneous lupus erythematosus (CCLE) remains unclear. Here, we compare B-cell and serum auto-antibody profiles between patients with systemic lupus erythematosus (SLE), CCLE, and overlap conditions.

METHODS

B-cells were compared by flow cytometry amongst healthy controls, CCLE without systemic lupus (CCLE+/SLE-) and SLE patients with (SLE+/CCLE+) or without CCLE (SLE+/CCLE-). Serum was analyed for autoreactive 9G4+, anti-double-stranded DNA, anti-chromatin and anti-RNA antibodies by ELISA and for anti-RNA binding proteins (RBP) by luciferase immunoprecipitation.

RESULTS

Patients with CCLE+/SLE- share B-cell abnormalities with SLE including decreased unswitched memory and increased effector B-cells albeit at a lower level than SLE patients. Similarly, both SLE and CCLE+/SLE- patients have elevated 9G4+ IgG autoantibodies despite lower levels of anti-nucleic acid and anti-RBP antibodies in CCLE+/SLE-. CCLE+/SLE- patients could be stratified into those with SLE-like B-cell profiles and a separate group with normal B-cell profiles. The former group was more serologically active and more likely to have disseminated skin lesions.

CONCLUSION

CCLE displays perturbations in B-cell homeostasis and partial B-cell tolerance breakdown. Our study demonstrates that this entity is immunologically heterogeneous and includes a disease segment whose B-cell compartment resembles SLE and is clinically associated with enhanced serological activity and more extensive skin disease. This picture suggests that SLE-like B-cell changes in primary CCLE may help identify patients at risk for subsequent development of SLE. B-cell profiling in CCLE might also indentify candidates who would benefit from B-cell targeted therapies.

Pathological role of activated mTOR in CXCR3+ memory B cells of rheumatoid arthritis

OBJECTIVES

B cells play an important pathological role in rheumatoid arthritis (RA). In this study, we investigated the role of metabolic regulator mTOR in B cells and its relevance to the pathology of RA.

METHODS

Peripheral blood mononuclear cells were isolated from 31 normal subjects and 86 RA patients and the gated B cells were assessed for mTOR phosphorylation and chemokine receptor expression. In vitro studies on peripheral blood B cells isolated from the control and RA patients investigated the molecular mechanisms.

RESULTS

Higher concentrations of CXCL10 (CXCR3 ligands) and lower percentages of CXCR3+ memory B cells were present in the peripheral blood of RA patients relative to the control. RA patients with high CXCL10 concentrations had smaller percentage of CXCR3+ memory B cells and high disease activity. One-year treatment with TNF inhibitors increased the percentage of CXCR3+ memory B cells and reduced serum CXCL10 concentrations. mTOR phosphorylation in B cells was further enhanced in RA patients, compared to the control, and was selectively enhanced in CXCR3+ memory B cells. mTOR phosphorylation in CXCR3+ memory B cells correlated with disease activity. In vitro, mTOR phosphorylation in B cells enhanced IL-6 production and increased RANKL expression.

CONCLUSION

mTOR activation in CXCR3+ memory B cells of RA patients is associated with disease activity, mediated through IL-6 production and RANKL expression. The obtained results also suggest that TNF inhibitors mediate an impact on the association between CXCL10 and mTOR activated CXCR3+ memory B cells.

JAK Inhibitors and Modulation of B Cell Immune Responses in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic, systemic immune-mediated inflammatory disease that can lead to joint destruction, functional disability and substantial comorbidity due to the involvement of multiple organs and systems. B cells have several important roles in RA pathogenesis, namely through autoantibody production, antigen presentation, T cell activation, cytokine release and ectopic lymphoid neogenesis. The success of B cell depletion therapy with rituximab, a monoclonal antibody directed against CD20 expressed by B cells, has further supported B cell intervention in RA development. Despite the efficacy of synthetic and biologic disease modifying anti-rheumatic drugs (DMARDs) in the treatment of RA, few patients reach sustained remission and refractory disease is a concern that needs critical evaluation and close monitoring. Janus kinase (JAK) inhibitors or JAKi are a new class of oral medications recently approved for the treatment of RA. JAK inhibitors suppress the activity of one or more of the JAK family of tyrosine kinases, thus interfering with the JAK-Signal Transducer and Activator of Transcription (STAT) signaling pathway. To date, there are five JAK inhibitors (tofacitinib, baricitinib, upadacitinib, peficitinib and filgotinib) approved in the USA, Europe and/ or Japan for RA treatment. Evidence from the literature indicates that JAK inhibitors interfere with B cell functions. In this review, the main results obtained in clinical trials, pharmacokinetic, in vitro and in vivo studies concerning the effects of JAK inhibitors on B cell immune responses in RA are summarized.

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.

Blood Lymphocyte Subsets for Early Identification of Non-Remission to TNF Inhibitors in Rheumatoid Arthritis

Background: TNF inhibitors (TNFis) are widely used for the treatment of rheumatoid arthritis (RA), although the response rates to this therapy in patients with RA remains heterogeneous and < 50% achieve remission (REM). Objective: To analyze baseline peripheral blood leukocytes profiles in order to search for biomarkers identifying patients who will most likely not achieve REM under TNFi treatment. Methods: A prospective bi-center pilot study including 98 RA patients treated with TNFis and followed-up during 6 months. Patients were classified according to DAS28 as follows: those who achieved REM (DAS28 ≤ 2.6) and those who did not (DAS28 > 2.6) at 6 months after starting TNFis. These rates were also assessed by simplified disease activity index (SDAI ≤ 3.3 and SDAI > 3.3, respectively). Peripheral blood immune cells were studied by flow cytometry before treatment initiation. Results: At 6 months, 61 or 80% of patients did not achieve REM by DAS28 or SDAI, respectively. Basal leukocyte profiles differed between REM vs. non-REM patients. Non-REM patients showed lower percentages of total and naïve B cells at baseline than REM subjects. A B lymphocyte/CD4+ lymphocyte ratio (BL/CD4 ratio) <0.2 clearly associated with a higher probability of non-REM status based on DAS28 at 6 months (OR = 9.2, p = 0.006). These data were confirmed when patient response was evaluated by SDAI index. Conclusion: Our results strongly suggest that BL/CD4 ratio could be considered as a useful biomarker for the early identification of non-remitters to TNFi in clinical practice.

B-cell profile, B-cell activating factor concentration and IgG levels in human cutaneous and mucosal leishmaniasis

AIMS

The aim of this study was to evaluate characteristics of B cells in human tegumentary leismaniasis (TL) analysing cutaneous leishmaniasis (CL), most prevalent form and mucosal leishmaniasis (ML), aggressive form characterized by the destruction of the oral-nasal-pharyngeal cavities.

METHODS AND RESULTS

By flow cytometry analysis, we found decreased percentages of non-class-switched memory B cells in TL with the degree of the loss related to clinical severity. Using commercial ELISA, we reported high levels of B-cell activating factor (BAFF) and IgG preferentially in aggressive CL and markedly in ML together with decreased BAFF receptors in the latter. We also found lower levels of BAFF after clinical recovery suggesting a relation between BAFF and disease activity. Mucosal leishmaniasis history of therapeutic failure presented high levels of BAFF accompanied by detectable concentrations of IFN-γ and IL-6 (assayed by commercial ELISA and cytometric bead arrays respectively), cytokines involved in exaggerated inflammatory responses and tissue damage in TL.

CONCLUSION

We demonstrate B-cell disturbances in TL with the degree of the alterations related to clinical severity. We suggest a relation between excess of BAFF and disease activity and point towards a possible implication of BAFF in the inflammatory phenomenon of ML.

Peripheral Blood Lymphocyte Analysis in Oligo- and Polyarticular Juvenile Idiopathic Arthritis Patients Receiving Methotrexate or Adalimumab Therapy: A Cross-Sectional Study

Juvenile idiopathic arthritis (JIA) is an umbrella term for seven distinct chronic immune-mediated diseases. Disease-modifying anti-rheumatic drugs (DMARD) are used to treat the underlying joint inflammation as well as extra-articular manifestations. Immunosuppression is a considerable side effect of the drugs. The main goal of this study was to investigate the effect of different JIA therapies on leukocyte subpopulations, which play a role in immune-defense. Three study groups were established. The first group consisted of JIA patients treated with methotrexate solely, the second one received a combination of methotrexate (MTX) and adalimumab (ADA). The control group was made up of the patients' healthy siblings. A total of 63 children were recruited. Fourty-one children with JIA and 22 healthy controls were included in the study. The absolute number of CD3+ T-cells was significantly elevated in patients treated with biological therapy compared to healthy controls (p2 = 0.017). In contrast, the number of CD56+ natural killer cells was significantly lower in children receiving biological therapy in comparison with healthy donors (p2 = 0.039). A significant alteration was also demonstrated between patients treated with MTX and MTX/ADA group concerning CD 19+ B-cells (p3 = 0.042). This is the first study that demonstrates significant alterations in the number of B-cells and T-cells with a relative decrease of NK-cell ratios in JIA patients receiving different DMARD therapy. Clinical Trial Registration: NCT03833271. 21.01.2019.

Rheumatoid arthritis patients display B-cell dysregulation already in the naïve repertoire consistent with defects in B-cell tolerance

B cells are postulated to be central in seropositive rheumatoid arthritis (RA). Here, we use exploratory mass cytometry (n = 23) and next-generation sequencing (n = 19) to study B-cell repertoire shifts in RA patients. Expression of several B-cell markers were significantly different in ACPA⁺ RA compared to healthy controls, including an increase in HLA-DR across subsets, CD22 in clusters of IgM⁺ B cells and CD11c in IgA⁺ memory. Moreover, both IgA⁺ and IgG⁺ double negative (IgD⁻ CD27⁻) CD11c⁺ B cells were increased in ACPA⁺ RA, and there was a trend for elevation in a CXCR5/CCR6^high transitional B-cell cluster. In the RA BCR repertoire, there were significant differences in subclass distribution and, notably, the frequency of VH with low somatic hypermutation (SHM) was strikingly higher, especially in IgG1 (p < 0.0001). Furthermore, both ACPA⁺ and ACPA⁻ RA patients had significantly higher total serum IgA and IgM compared to controls, based on serology of larger cohorts (n = 3494 IgA; n = 397 IgM). The observed elevated Ig-levels, distortion in IgM⁺ B cells, increase in double negative B cells, change in B-cell markers, and elevation of unmutated IgG⁺ B cells suggests defects in B-cell tolerance in RA. This may represent an underlying cause of increased polyreactivity and autoimmunity in RA.

Peripheral Blood B and T Cell Profiles in Children with Active Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis (JIA) is one of the most common autoimmune diseases in children. Our study aimed to evaluate the peripheral blood B and T lymphocyte subpopulations in children with JIA. This case-control study included 20 children with JIA as well as 20 healthy children with matching age and sex as a control group. All patients included in the study were in activity as determined by visual analog scale. In addition to complete clinical evaluation, basic investigations, peripheral blood B and T lymphocyte subpopulations were done to all participants by flow cytometry. JIA patients displayed a significant decrease in IgM memory B lymphocytes, switched memory B lymphocytes, and total memory B lymphocytes when compared to the healthy controls. The percentages of naïve B lymphocytes were significantly increased in JIA patients than in controls. Total T lymphocytes, CD8⁺CD28^null cells, and CD4⁺CD28^null cells were significantly increased in JIA patients as compared to controls. In conclusion; JIA patients have an alteration in both B and T lymphocytes with the predisposition of memory cells which may have a role in sustaining the JIA disease activity.

The B side of rheumatoid arthritis pathogenesis

In the last years, a dramatic amount of research has been performedincreasing the knowledge about the biological mechanism underpinning Rheumatoid Arthritis (RA) inflammation, putting B lymphocytes in the center of RA pathogenesis. Nowadays, B cell phenotypes and autoantibodies positivity arose as important biomarkers in early and long-standing disease. Moreover, comparative analysis of peripheral blood and synovial tissue compartments enables the identification of novel physiopathological mechanisms promoting inflammation. In this narrative review we will discuss the biological relevance of B cell derived autoimmunity and in RA course, from disease onset to remission achievement.

CD21-/low B cells associate with joint damage in rheumatoid arthritis patients

Depletion of B cells is beneficial in rheumatoid arthritis (RA) patients with autoantibodies to citrullinated proteins (ACPA) and/or the Fc portion of immunoglobulins (rheumatoid factor [RF]), suggesting a role for B cells in disease pathogenesis. To date, however, the identity of specifically pathogenic B cell subsets has not been discovered. One candidate population is identified by the low expression or absence of complement receptor 2 (CD21^-/low B cells). In this study, we sought to determine whether there was any correlation between CD21^-/low B cells and clinical outcome in patients with established RA, either ACPA⁺ /RF⁺ (n = 27) or ACPA^- /RF^- (n = 10). Healthy donors (n = 17) were included as controls. The proportion of the CD21^-/low CD27^- IgD^- memory B cell subset in peripheral blood (PB) was significantly increased in ACPA⁺ /RF⁺ RA patients compared with healthy donors, and the frequency of this subset correlated with joint destruction (r = 0.57, P < 0.04). The levels of the chemokines CXCL-9 and CXCL-10 were higher in synovial fluid than in plasma, and PB CD21^-/low cells expressed the receptor, CXCR3. In synovial fluid, most of the B cells were CD21^-/low , approximately 40% of that population was CD27^- IgD^- , and a third of those expressed the pro-osteoclastogenic factor receptor activator of the nuclear factor κB ligand (RANKL). This subset also secreted RANKL, in addition to other factors such as IL-6, even in the absence of stimulation. We interpret these data as reason to propose the hypothesis that the CD27^- IgD^- subset of CD21^-/low B cells may mediate joint destruction in patients with ACPA⁺ /RF⁺ RA.

Exploiting CD22 To Selectively Tolerize Autoantibody Producing B-Cells in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that primarily affects the synovial joints and can lead to bone erosion and cartilage damage. One hallmark of RA is anticitrullinated protein autoantibodies (ACPA) and memory citrulline-specific B-cells, which have been implicated in RA pathogenesis. While depletion of B-cells with Rituximab improves clinical responses in RA patients, this treatment strategy leaves patients susceptible to infections. Here we use of Siglec-engaging Tolerance-inducing Antigenic Liposomes (STALs) to selectively target the citrulline-specific B-cells. ACPA production from purified human RA patients' B-cells in vitro was achieved through a set of stimulation conditions, which includes the following: BAFF, anti-CD40, IL-21, and LPS. In vivo generation of citrulline specific B-cells and ACPA production was accomplished by antigenic liposomes consisting of monophosphoryl lipid A (MPLA) and a cyclic citrullinated peptide (CCP) administered to SJL/J mice. We show that STALs that codisplay a high affinity CD22 glycan ligand and synthetic citrullinated antigen (CCP STALs) can prevent ACPA production from RA patients' memory B-cells in vitro. These CCP STALs were also effective in inducing tolerance to citrullinated antigens in SJL/J mice. The results demonstrate that tolerization of the B-cells responsible for ACPA can be achieved by exploiting the inhibitory receptor CD22 with high-affinity glycan ligands. Such a treatment strategy could be beneficial in the treatment of RA.

Evaluation of SUMO1 and POU2AF1 in whole blood from rheumatoid arthritis patients and at risk relatives

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by chronic and symmetrical inflammation of synovial tissue with subsequent joint destruction. SUMO1 is an important regulator of apoptosis through non-canonical mechanism in synovial fibroblasts, and POU2AF1 is a known B-cell transcriptional co-activator. The specific objective of this study was to measure the expression of SUMO1 and POU2AF1 on first-degree relatives of patients with RA and also in the preclinical and clinical stages of RA and describe their possible role in RA physiopathology. Blood samples were collected from ACPA+, ACPA-, early and established RA subjects recruited. ACPAs and CarP autoantibodies were determined by ELISA Eurodiagnostica CCplus kit according to previously described protocols. RNA was isolated from blood samples; the purity as integrity was determined. Gene expression analysis was made by RT-qPCR using specific primers for SUMO1 and POU2AF1 mRNAs; relative expression was determined according to the 2^-ΔΔct method procedure. Significant differences in the expression of both, SUMO1 and POU2AF1 were identified when comparing arthritis versus healthy or ACPA+ individuals, suggesting that the down regulation of such genes starts after the onset of symptoms in RA patients. Also, a significant correlation was identified for POU2AF1 and disease progression whit a downward trend for those with established RA. The implications of such gene down regulation are discussed in the context of RA physiopathology.

Lymphocytes as Biomarkers of Therapeutic Response in Rheumatic Autoimmune Diseases, Is It a Realistic Goal?

Many therapies are available for patients with rheumatoid arthritis (RA) while biological therapies have limited effects in patients with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS). In both cases, biomarkers predicting drug response would be very useful to guide clinicians in their choice. We performed a systematic review to evaluate the value of lymphocyte phenotyping as a marker of therapeutic response. Of the 1063 articles retrieved, 39 fulfilled inclusion criteria and were included in the present review (25 for RA, 10 for SLE, and 4 for pSS). Lymphocyte phenotyping was described as a biomarker of therapeutic response in many studies, but most results could not be confirmed by independent teams using multivariate analysis. The most consistent result might be the association between rituximab response and the levels of memory B cells before therapy, although some studies were controversial. Thus, lymphocyte phenotyping cannot yet be proposed as a biomarker of response in rheumatic autoimmune diseases. The lack of reproducibility between studies may be explained by technical issues influencing lymphocyte phenotyping so standardization procedures should be developed for future studies. The patients' characteristics vary between studies, and large population studies, including a wide range of patients' characteristics and biomarkers, are required to provide predictive models for clinical outcomes. The use of new flow cytometry techniques such as single-cell mass cytometry technology might also help finder reliable biomarkers in the future.

Higher frequencies of circulating ICOS+, IL-21+ T follicular helper cells and plasma cells in patients with new-onset membranous nephropathy

BACKGROUND

T follicular helper (TFH) cells and B cells are known to regulate humoral immune responses. This study is aimed at examining the putative contribution of different subsets of circulating of TFH cells and B cells to membranous nephropathy (MN).

METHODS

A total of 45 MN patients and 19 healthy controls (HCs) were examined for the number of TFH cells and B cells by flow cytometry. The level of 24-h urinary protein and eGFR were calculated, and the level of serum cytokines was examined. The potential association among these measures was analyzed.

RESULTS

Compared to the HCs, MN patients had significantly higher numbers of circulating CD4⁺CXCR5⁺, CD4⁺CXCR5⁺ICOS⁺, CD4⁺CXCR5⁺CD154⁺, CD4⁺CXCR5⁺IL-21⁺, and CD4⁺CXCR5⁺CD28⁺ TFH cells, as well as IgD⁺CD27^-CD19⁺ and CD138⁺CD19⁺ B cells. However, the number of IgD⁺CD27⁺CD19⁺ B cells was significantly lower in MN patients than in the HC. The levels of serum IL-21, IL-2, IL-4, IL-10, IL-17A, and IFN-γ were significantly higher in MN patients than in the HC. Furthermore, the numbers of CD4⁺CXCR5⁺, CD4⁺CXCR5⁺ICOS⁺, CD4⁺CXCR5⁺CD154⁺, CD4⁺CXCR5⁺IL-21⁺, CD4⁺CXCR5⁺CD28⁺ TFH cells, CD138⁺CD19⁺ B cells, and the level of sera IL-21 were negatively correlated with the values of eGFR, but positively correlated with the levels of 24-h urinary proteins. Following treatment, the numbers of CD4⁺CXCR5⁺, CD4⁺CXCR5⁺ICOS⁺, CD4⁺CXCR5⁺CD154⁺, CD4⁺CXCR5⁺IL-21⁺, CD4⁺CXCR5⁺CD28⁺ TFH cells, CD138⁺CD19⁺ B cells, and the levels of IL-21 were significantly reduced. In contrast, IL-4 and IL-10 levels were noticeably increased after treatment.

CONCLUSIONS

Data suggest that activated TFH and plasma cells may contribute to the pathogenesis of MN.

B-cell phenotype and IgD-CD27- memory B cells are affected by TNF-inhibitors and tocilizumab treatment in rheumatoid arthritis

Background

The use of TNF-inhibitors and/or the IL-6 receptor antagonist, tocilizumab, in rheumatoid arthritis (RA) have pleiotropic effects that also involve circulating B-cells. The main goal of this study was to assess the effect of TNF-inhibitors and tocilizumab on B-cell phenotype and gene expression in RA.

Methods

Blood samples were collected from untreated early RA (ERA) patients, established RA patients under methotrexate treatment, established RA patients before and after treatment with TNF-inhibitors and tocilizumab, and healthy donors. B-cell subpopulations were characterized by flow cytometry and B-cell gene expression was analyzed by real-time PCR on isolated B-cells. Serum levels of BAFF, CXCL13 and sCD23 were determined by ELISA.

Results

The frequency of total CD19+ B cells in circulation was similar between controls and all RA groups, irrespective of treatment, but double negative (DN) IgD-CD27- memory B cells were significantly increased in ERA and established RA when compared to controls. Treatment with TNF-inhibitors and tocilizumab restored the frequency of IgD-CD27- B-cells to normal levels, but did not affect other B cell subpopulations. TACI, CD95, CD5, HLA-DR and TLR9 expression on B-cells significantly increased after treatment with either TNF-inhibitors and/ or tocilizumab, but no significant changes were observed in BAFF-R, BCMA, CD69, CD86, CXCR5, CD23, CD38 and IgM expression on B-cells when comparing baseline with post-treatment follow-ups. Alterations in B-cell gene expression of BAFF-R, TACI, TLR9, FcγRIIB, BCL-2, BLIMP-1 and β2M were found in ERA and established RA patients, but no significant differences were observed after TNF-inhibitors and tocilizumab treatment when comparing baseline and follow-ups. Serum levels of CXCL13, sCD23 and BAFF were not significantly affected by treatment with TNF-inhibitors and tocilizumab.

Conclusions

In RA patients, the use of TNF-inhibitors and/ or tocilizumab treatment affects B-cell phenotype and IgD-CD27- memory B cells in circulation, but not B-cell gene expression levels.

Changes in peripheral blood lymphocyte subsets during arthritis development in arthralgia patients

BACKGROUND

Multiple lymphocyte subsets like T and B cells have been connected to joint infiltration and inflammation in rheumatoid arthritis (RA). Identification of leucocyte subsets that are dysregulated in arthritis development could provide insight into the aetiology of RA. This study aimed to investigate the composition of the peripheral blood components, i.e. CD14(+) monocytes, CD4(+) and CD8(+) T lymphocytes (CD3(+)), CD80(+), C-X-C chemokine receptor 3 (CXCR3)(+) and CD27(+) B lymphocytes (CD19(+)), CD16(+)CD56(+)CD3(-) natural killer (NK) cells and activated CD56(+)CD3(+) T cells, for association with arthritis development in patients with arthralgia.

METHODS

Peripheral blood was collected from 89 patients with early RA (disease duration <6 months), 37 healthy controls (HC) and 113 patients with arthralgia (22 developed arthritis within ≤1 year, 18 developed arthritis after >1 year and 73 did not develop arthritis). Absolute numbers of monocytes and lymphocyte subsets in whole heparinized blood were determined with flow cytometry using quantification beads in combination with fluorescent labelled antibodies for T cells, B cells, monocytes, NK cells and activated T cells.

RESULTS

In patients with early RA, significant decreases in numbers of (activated) T cells, CD80(+) and memory B cells and a trend towards smaller numbers of CD8(+) T cells was observed compared to HC. Similar differences were seen in patients with arthralgia who developed or did not develop arthritis (non-converters), with significantly decreased CD8(+) T cells and memory B cells. Patients with arthralgia who developed arthritis were split into groups that developed arthritis within 1 year (early converters) or after 1 year (late converters). Late converters had a significantly decreased number of CD8(+) T cells compared to non-converters; early converters had a decreased number of memory B cells. Longitudinal analysis of converters showed a significant relative increase in CD80(+) B cells towards the conversion time point compared to 24 months prior to conversion.

CONCLUSIONS

This study revealed that patients with arthralgia who develop arthritis demonstrate a change in cellular immune parameters apparent in the periphery, starting with a decrease in cytotoxic T cells 24 months prior to arthritis development, followed by a decrease in the number of memory B cells 12 months prior to disease onset.

Rheumatoid Arthritis, Immunosenescence and the Hallmarks of Aging

Age is the most important risk factor for the development of infectious diseases, cancer and chronic inflammatory diseases including rheumatoid arthritis (RA). The very act of living causes damage to cells. A network of molecular, cellular and physiological maintenance and repair systems creates a buffering capacity against these damages. Aging leads to progressive shrinkage of the buffering capacity and increases vulnerability. In order to better understand the complex mammalian aging processes, nine hallmarks of aging and their interrelatedness were recently put forward.

RA is a chronic autoimmune disease affecting the joints. Although RA may develop at a young age, the incidence of RA increases with age. It has been suggested that RA may develop as a consequence of premature aging (immunosenescence) of the immune system. Alternatively, premature aging may be the consequence of the inflammatory state in RA. In an effort to answer this chicken and egg conundrum, we here outline and discuss the nine hallmarks of aging, their contribution to the pre-aged phenotype and the effects of treatment on the reversibility of immunosenescence in RA.

Expression of Toll-like receptor -7 and -9 in B cell subsets from patients with primary Sjögren's syndrome

Introduction

Sjögren’s syndrome (SS) is a rheumatic autoimmune disease characterized by inflammation of exocrine glands. As autoantibodies are present in a majority of patients, B cells have been suggested to play an important role in onset and development of the disease. Toll-like receptors (TLRs) are pattern recognition receptors triggering innate immune responses. Since an increased expression of TLRs has been detected in other rheumatic diseases the purpose of this study was to explore TLRs in B cells of SS patients.

Methods

The expression of TLR-7 and -9 in B cell subsets of 25 patients with primary SS (pSS) and 25 healthy controls was analysed in peripheral blood using flow cytometry and real time quantitative PCR.

Results

We detected similar levels of CD19⁺ B cells in pSS patients and healthy controls. An increased number of naïve B cells, as well as fewer pre-switched memory B cells were found in pSS patients. No significant differences were observed in TLR-7 and -9 expression in B cells between pSS patients and healthy controls.

Conclusion

This study shows that pSS patients have an alteration in the B cell subpopulation composition compared to controls, with less pre-switched memory B cells and more naïve B cells. We did not detect any significant disparities in TLR-7 and -9 expression between the two groups.

Polychromatic flow cytometry in evaluating rheumatic disease patients

B cells are central players in multiple autoimmune rheumatic diseases as a result of the imbalance between pathogenic and protective B-cell functions, which are presumably mediated by distinct populations. Yet the functional role of different B-cell populations and the contribution of specific subsets to disease pathogenesis remain to be fully understood owing to a large extent to the use of pauci-color flow cytometry. Despite its limitations, this approach has been instrumental in providing a global picture of multiple B-cell abnormalities in multiple human rheumatic diseases, more prominently systemic lupus erythematosus, rheumatoid arthritis and Sjogren’s syndrome. Accordingly, these studies represent the focus of this review. In addition, we also discuss the added value of tapping into the potential of polychromatic flow cytometry to unravel a higher level of B-cell heterogeneity, provide a more nuanced view of B-cell abnormalities in disease and create the foundation for a precise understanding of functional division of labor among the different phenotypic subsets. State-of-the-art polychromatic flow cytometry and novel multidimensional analytical approaches hold tremendous promise for our understanding of disease pathogenesis, the generation of disease biomarkers, patient stratification and personalized therapeutic approaches.

Increased circulating follicular helper T cells and activated B cells correlate with disease severity in patients with psoriasis

BACKGROUND

Follicular Helper T (TFH) Cells are a population of recently discovered CD4(+) T cells involved in autoimmune diseases. However, the contribution of TFH cells in patients with psoriasis remains unknown.

OBJECTIVE

We aimed to investigate the levels of TFH cells, B cells and their clinical relevance in patients with psoriasis.

METHODS

Using multi-colour flow cytometry, we detected different subsets of TFH cells and B cells in the peripheral blood of 27 patients with psoriasis and 13 healthy donors. Serum IL-21 levels were measured by ELISA. The relationship between the levels of TFH cells, IL-21, B cells and disease severity were analysed.

RESULTS

Compared with healthy donors, higher levels of circulating CD3(+) CD4(+) CXCR5(+) cells, CD3(+) CD4(+) CXCR5(+) ICOS(+), CD3(+) CD4(+) CXCR5(+) PD-1(+), CD3(+) CD4(+) CXCR5(+) ICOS(+) PD-1(+) TFH cells and CD19(+) IgD(+) CD27(-) naive B, CD19(+) CD86(+) activated B, but lower levels of CD19(+) IgD(+) CD27(+) preswitch and CD19(+) IgD(-) CD27(+) postswitch memory B cells, were observed in patients with psoriasis. In addition, serum IL-21 levels in patients with psoriasis were significantly higher than those in healthy donors, and showed to be positively correlated with the levels of different subsets of TFH cells, and the level of CD19(+) CD86(+) B cells was also correlated with TFH cells and IL-21 levels. Furthermore, a significant correlation was found between the levels of CD3(+) CD4(+) CXCR5(+) ICOS(+) TFH cells, CD3(+) CD4(+) CXCR5(+) ICOS(+) PD-1(+) TFH cells, CD19(+) CD86(+) B cells and IL-21 with Psoriasis Area and Severity Index scores.

CONCLUSION

The levels of TFH cells and activated B cells were increased in the peripheral blood of patients with psoriasis, and positively correlated with disease severity. These results suggest that TFH cells and activated B cells may play a role in the pathogenesis of psoriasis.

Bone resorption correlates with the frequency of CD5⁺ B cells in the blood of patients with rheumatoid arthritis

OBJECTIVE

The prevention of bone resorption and subsequent joint destruction is one of the main challenges in the treatment of patients suffering from RA. Various mechanisms have previously been described that contribute to bone resorption in tightly defined cohorts. Here we analysed a cross-sectional cohort of RA patients and searched for humoral and cellular markers in the peripheral blood associated with bone resorption.

METHODS

We enrolled 61 consecutive RA patients positive for ACPA. Blood was analysed by flow cytometry to determine the percentages of regulatory T cells and B cell subpopulations. Cytokine (TNF-α, IL-6, IL-10) and ACPA levels as well as the bone resorption marker CTX-1 were determined from the patients' sera. Standard clinical disease parameters were included.

RESULTS

Multivariate analyses showed that the percentages of CD5(+) B cells were positively correlated with CTX-1 serum levels. However, neither low-avidity ACPA nor serum IL-6 levels, both known to be produced by CD5(+) cells, were associated with CTX-1 in patients' sera. There was no correlation between CTX-1 levels and clinical parameters or ACPA levels.

CONCLUSION

In summary, we found that the CD5(+) B cell population is associated with bone resorption as measured via serum CTX-1 levels in a cross-sectional cohort of RA patients. However, a possible functional link between CD5(+) B cells and bone resorption still needs to be defined.

Memory B cell subsets and plasmablasts are lower in early than in long-standing rheumatoid arthritis

BACKGROUND

Alterations of B cell subset distribution have been described in the peripheral blood (PB) of rheumatoid arthritis (RA) patients, but no data are available on differences between the onset and the established phases of the disease. The purpose of the study was to clarify whether a peculiar distribution of B cell subsets characterizes RA onset, thus leading to a more favorable clinical response to treatment, and to evaluate the possible association of a particular B cell subpopulation with response to therapy.

RESULTS

122 RA patients were enrolled: 25 had symptom duration less than 3 months and were defined as having "very early RA" (VERA), and 43 had symptom duration from more than 3 months up to one year (early-RA: ERA). The other 54 RA patients had long-standing RA (LSRA). At baseline and at 6-month follow-up visit peripheral blood samples were collected and analyzed by flow cytometry for the distribution of circulating B cell subsets by staining with surface markers CD45, CD19, CD38, CD27 and IgD and intracellular marker ZAP70.VERA and ERA patients showed higher percentages and absolute counts of circulating antigen inexperienced naïve B cells (IgD + CD27-) and lower percentages and absolute numbers of double negative (IgD-CD27-) memory B cells and plasmablasts (CD38 + CD27+) compared to LSRA patients. At the multivariate analysis, a higher frequency of naïve B cells (IgD + CD27-) at baseline arose as significant predictor of CDAI remission, together with "having VERA disease" and a low disease activity at baseline.

CONCLUSIONS

The onset of RA is characterized by higher percentages and absolute numbers of naïve B cells and lower numbers of plasmablasts and double negative memory B cells compared to established RA. Naïve B cells could represent a promising biomarker of outcome.

Peripheral and synovial mechanisms of humoral autoimmunity in rheumatoid arthritis

One of the hallmarks of rheumatoid arthritis (RA) is the development of humoral autoimmunity resulting in circulating autoantibodies. The clinical efficacy of B cell-depleting biologic treatments highlighted a key role for autoreactive B cell activation in the pathogenesis of RA. In this review, we discuss the key mechanisms leading to breach of B cell self-tolerance in the peripheral compartment. We also highlight the contribution of synovial ectopic lymphoid structures (ELS) in the development of functional niches of autoreactive B cells promoting humoral autoimmunity in the inflamed RA joints over and above secondary lymphoid organs (SLO).

B cells in rheumatoid arthritis: from pathogenic players to disease biomarkers

The therapeutic benefit of depleting B cells in rheumatoid arthritis (RA) has refocused attention on B cells with increasing awareness on their role in autoimmunity and their function beyond autoantibody production. The rapid increase in our comprehension of B-cell pathobiology is progressively opening novel perspectives in the area of B cell-targeted therapies with the expectation to define more specific approaches able to preserve the homeostasis of the humoral response while disrupting the pathogenic components. In parallel, B-cell activity in RA is starting to be explored in its clinical value, in search of novel biomarkers embedded in the pathogenic process that could help classifying the disease and predicting its heterogeneous outcome beyond inflammation dynamics. In this review, we summarize current knowledge on the multiple roles that B cells play in several aspects of RA. We also analyze their distribution and potential function in different anatomic compartments with specific reference to the main sites in which the disease may be sustained and exert its detrimental effects: the systemic circulation, synovium, bone marrow, and draining lymph nodes. We also highlight novel data encouraging further research in the field of biomarkers related to B cells and their regulatory factors.

Changes in peripheral blood B cell subsets at diagnosis and after treatment with disease-modifying anti-rheumatic drugs in patients with rheumatoid arthritis: correlation with clinical and laboratory parameters

OBJECTIVE

To assess variation in peripheral blood B lymphocyte subsets in rheumatoid arthritis (RA).

METHODS

B lymphocyte subsets in disease-modifying anti-rheumatic drug (DMARD)-naïve patients with RA (n = 30), patients with RA treated with DMARDs (n = 73) and healthy controls (n = 46) were analyzed by flow cytometry. Total B cells, total memory B cells, immunoglobulin M (IgM) memory B cells, switched memory B cells, non-switched memory B cells, CD21lo B cells, transitional B cells and plasmablasts were measured. Correlation with clinical and laboratory parameters was performed.

RESULTS

Total memory B cells, IgM memory B cells and non-switched memory B cells were reduced in RA patients at diagnosis compared to controls (P < 0.05). In patients with treated RA, there was a further reduction of total B cells, CD21lo cells, transitional B cells and plasmablasts, compared to controls (P < 0.05). The reduction in absolute numbers of total B cells, switched memory B cells, CD21lo cells, transitional B cells and plasmablasts in treated RA patients was significant (P < 0.05) even when compared to the DMARD-naïve patients. Only treatment responders (Disease Activity Score < 3.2) had reduced total B cells and absolute numbers of switched and IgM memory B cells (P < 0.05). In patients requiring leflunomide, total memory B cells, IgM memory B cells, non-switched memory B cells and absolute numbers of switched memory B cells were reduced compared with the remainder of the patient group (P < 0.05).

CONCLUSION

There is reduction of various B cell subsets in RA patients at diagnosis. Treatment with DMARDs leads to further reduction in additional B cell subsets without correction of the abnormalities. Reduction in individual subsets may predict RA patients requiring more intensive therapy.

Abatacept reduces levels of switched memory B cells, autoantibodies, and immunoglobulins in patients with rheumatoid arthritis

OBJECTIVE

Abatacept (ABA) is a chimeric molecule, able to block the CD28-mediated costimulatory pathway. To evaluate the hypothesis that, through this mechanism of action, ABA may down-modulate the immune responses of B lymphocytes in rheumatoid arthritis (RA), we investigated the serum levels of immunoglobulins (Ig), free light chains (FLC), anticitrullinated protein antibodies (ACPA), and rheumatoid factor (RF), as well as the number of B lymphocytes differentiated into post-switch memory cells in patients treated with ABA.

METHODS

The serum levels of Ig, FLC, different ACPA, RF isotypes, and the B cell phenotype were longitudinally evaluated in 30 patients with RA treated with ABA.

RESULTS

At baseline, the proportion of total and post-switch memory B cells was lower in RA than in healthy individuals. After 6 months of ABA treatment we observed significant reductions of serum levels of IgG, IgA, and IgM, as well as FLC, with a normalization in many patients who had initially abnormal values. A significant reduction of the titers of IgG- and IgA-ACPA, as well as of IgM-, IgA-, and IgG-RF was also observed. A decrease of autoantibodies below the upper limits of normal values was found in 2 of 26 patients (8%) initially seropositive for IgG-ACPA, 1 of 14 (7%) for IgA-ACPA, 5 of 22 (23%) for IgM-RF, 7 of 22 (30%) for IgA-RF, and 5 of 16 (31%) for IgG-RF. After treatment, the proportion of circulating post-switch memory B cells was also further significantly decreased.

CONCLUSION

ABA treatment in patients with RA can reduce signs of polyclonal B cell activation, inducing a trend toward normalization of serum levels of different classes of Ig and of FLC, decreasing titers of ACPA and RF, and percentages of post-switch memory B cells.

High frequencies of activated B cells and T follicular helper cells are correlated with disease activity in patients with new-onset rheumatoid arthritis

This study aimed to examine the frequency of different subsets of circulating B and T follicular helper (Tfh) cells in patients with new-onset rheumatoid arthritis (RA) and following standard therapies. Twenty-five RA patients and 15 healthy controls (HC) were recruited for characterizing the frequency of CD27⁺, immunoglobulin (Ig)D⁺, CD86⁺, CD95⁺, Toll-like receptor (TLR)-9⁺ B cells and inducible T cell co-stimulator (ICOS) and programmed death 1 (PD-1)-positive Tfh cells and the level of serum interleukin (IL)-21. The potential correlation between the frequency of different subsets of B and Tfh cells and the values of clinical measures in RA patients was analysed. In comparison with HC, significantly higher percentages of circulating IgD⁺ CD27⁻ CD19⁺ naive B, CD86⁺ CD19⁺ and CD95⁺ CD19⁺ activated B, CD3⁺ CD4⁺ CXCR5⁺, CD3⁺ CD4⁺ CXCR5⁺ ICOS⁺, CD3⁺ CD4⁺ CXCR5⁺ PD-1⁺ and CD3⁺ CD4⁺ CXCR5⁺ ICOS⁺ PD-1⁺ Tfh cells but lower IgD⁺ CD27⁺ CD19⁺ preswitch memory B cells were detected, accompanied by significantly higher levels of serum IL-21 in the RA patients. Furthermore, the percentages of CD95⁺ B cells were correlated positively with the frequency of PD-1⁺ Tfh cells, but negatively with ICOS⁺ Tfh cells. The percentages of CD86⁺ B cells and ICOS⁺ Tfh cells were correlated positively with the values of disease activity score 28 (DAS28). Following the drug therapies for 1 month, the percentages of CD86⁺ B and PD-1⁺ Tfh cells were reduced significantly in the drug-responding patients. Our data suggest that activated B and Tfh cells may contribute to the pathogenesis of RA and the frequency of activated B and Tfh cells may be used as biomarkers for evaluating the therapeutic responses of individual patients with RA.

BAFF and TACI gene expression are increased in patients with untreated very early rheumatoid arthritis

OBJECTIVE

B cells play important roles in rheumatoid arthritis (RA). Given the beneficial effect of B cell depletion therapy in RA as well as the observed alterations in B cell subpopulations in this disease, we evaluated whether changes in the expression of genes related to B cell survival and activation were already present in patients with untreated very early RA (VERA; < 6 weeks of disease duration).

METHODS

The expression of a group of B cell-related activation and survival genes was quantified in peripheral blood mononuclear cells from patients with VERA by real-time PCR and compared with untreated early RA (< 1 year), established treated RA, and other untreated early arthritis conditions. Serum B cell-activating factor belonging to the tumor necrosis factor family (BAFF) was quantified by ELISA.

RESULTS

BAFF gene expression and serum levels were highest in patients with VERA. The expression of BAFF receptor (BAFF-R) increased with disease progression, while transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) was elevated since the first weeks of RA onset. Paired box 5 gene expression was also increased at all RA stages. Chemokine (C-X-C motif) receptor 5 was elevated only in established RA. No differences were observed in B cell maturation antigen, activation-induced cytidine deaminase, B lymphocyte-induced maturation protein, and B cell lymphoma 2 expression.

CONCLUSION

Disturbances in the expression of B cell-related activation and survival genes, particularly BAFF and TACI, occur from the onset of RA and precede changes in BAFF-R. These alterations can lead to the development of autoreactive B cells from the first weeks of RA onset.

Molecular signature in HCV-positive lymphomas

Hepatitis C virus (HCV) is a positive, single-stranded RNA virus, which has been associated to different subtypes of B-cell non-Hodgkin lymphoma (B-NHL). Cumulative evidence suggests an HCV-related antigen driven process in the B-NHL development. The underlying molecular signature associated to HCV-related B-NHL has to date remained obscure. In this review, we discuss the recent developments in this field with a special mention to different sets of genes whose expression is associated with BCR coupled to Blys signaling which in turn was found to be linked to B-cell maturation stages and NF-κb transcription factor. Even if recent progress on HCV-B-NHL signature has been made, the precise relationship between HCV and lymphoma development and phenotype signature remain to be clarified.

B effector cells in rheumatoid arthritis and experimental arthritis

Rheumatoid arthritis is a chronic autoimmune immune disease affecting approximately 1% of the population. There has been a renewed interest in the role of B cells in rheumatoid arthritis based on the evidence that B cell depletion therapy is effective in the treatment of disease. This review summarizes the current knowledge of the mechanisms by which B cells contribute to autoimmune arthritis including roles as autoantibody producing cells, antigen-presenting cells, cytokine producing cells, and regulatory cells.

In vivo effects of the anti-interleukin-6 receptor inhibitor tocilizumab on the B cell compartment

OBJECTIVE

Interleukin-6 (IL-6) receptor inhibition by tocilizumab was recently licensed for the treatment of rheumatoid arthritis (RA). IL-6 induces in vitro differentiation of B cells into antibody-forming cells; however, the in vivo effects of IL-6 inhibition on the B cell compartment are currently not known. The purpose of this study was to examine this feature.

METHODS

Sixteen patients with active RA were treated in an open-label study with tocilizumab (8 mg/kg every 4 weeks). Immunophenotyping was performed at baseline, week 12, and week 24.

RESULTS

Memory B cell subsets declined significantly during tocilizumab therapy. Preswitch memory B cells decreased from a median of 19.6% to 12.3% at week 24 and postswitch memory B cells declined from a median of 18.6% to 15.0% at week 24 (P = 0.04). In parallel, CD19+IgA+ and CD19+IgG+ B cells decreased significantly. The proportion of IgA-expressing B cells fell from a median of 9.2% at baseline to 4.3% at week 12 and to 3.6% at week 24 (P = 0.01). IgG+ B cells declined from a median of 6.7% at baseline to 4.9% at week 12 (P = 0.007) and 2.8% at week 24 (P = 0.01). In parallel, serum levels of IgA and IgG were significantly diminished at week 24 (P < 0.05). There was a good correlation between relative and absolute numbers of IgA+ B cells with serum IgA at week 24.

CONCLUSION

Tocilizumab induced a significant reduction in the frequency of peripheral preswitch and postswitch memory B cells. In addition, the number of IgG+ and IgA+ B cells declined and correlated well with reduced serum immunoglobulin levels. The data indicate that IL-6 blockade affects the B cell hyperreactivity in RA patients.

Rheumatoid arthritis: what is refractory disease and how to manage it?

Despite the enthusiastic progresses in the field of rheumatoid arthritis pharmacotherapy the presence of prognostic factors associated with an unfavorable outcome and the inappropriate and/or delayed initiation of DMARDs can diminish the likelihood of achieving remission and increase the probability of refractoriness to treatment. During the last decade we have experience exciting developments regarding the approval of new treatment options but few patients are reaching sustained remission and refractory patients continue to be a problem. Thus, it is critical to understand how clinicians can decrease the risk of refractoriness by close monitoring disease activity, using well defined and accepted composite measures, and by early and optimized use of DMARDs, including biologics. The goal of this review paper is to offer an evidence based roadmap to prevent and to deal with refractory RA.

Cytokine pattern in very early rheumatoid arthritis favours B-cell activation and survival

OBJECTIVES

B cells play an important role in the perpetuation of RA, particularly as autoantibody-producing cells. The ICs that further develop deposit in the joints and aggravate the inflammatory process. However, B-cell contribution in the very early stage of the disease remains unknown. The main goal of this work was to determine the concentration of cytokines potentially relevant for B-cell activation in serum from very early polyarthritis patients, with <6 weeks of disease duration, who latter on evolved into very early RA (VERA).

METHODS

A proliferation-inducing ligand (APRIL), B-cell activating factor (BAFF) and IL-21 levels were measured by ELISA in the serum of VERA, other very early arthritis (VEA), established RA patients and controls. SF samples of established RA were also analysed.

RESULTS

VERA patients have higher levels of APRIL and BAFF as compared with VEA, established RA and controls. Furthermore, APRIL and BAFF levels are also significantly elevated in RA-SF when compared with serum.

CONCLUSIONS

The increased levels of APRIL and BAFF in VERA patients suggests that B-cell activation and the development of autoreactive B-cell responses might be crucial in early phases of RA. Therefore, APRIL and BAFF could be promising targets for therapy in the early phase of RA.