Distinct effects of methotrexate and etanercept on the B cell compartment in patients with juvenile idiopathic arthritis

Integrating single cell expression quantitative trait loci summary statistics to understand complex trait risk genes

Transcriptome-wide association study (TWAS) is a popular approach to dissect the functional consequence of disease associated non-coding variants. Most existing TWAS use bulk tissues and may not have the resolution to reveal cell-type specific target genes. Single-cell expression quantitative trait loci (sc-eQTL) datasets are emerging. The largest bulk- and sc-eQTL datasets are most conveniently available as summary statistics, but have not been broadly utilized in TWAS. Here, we present a new method EXPRESSO (EXpression PREdiction with Summary Statistics Only), to analyze sc-eQTL summary statistics, which also integrates 3D genomic data and epigenomic annotation to prioritize causal variants. EXPRESSO substantially improves existing methods. We apply EXPRESSO to analyze multi-ancestry GWAS datasets for 14 autoimmune diseases. EXPRESSO uniquely identifies 958 novel gene x trait associations, which is 26% more than the second-best method. Among them, 492 are unique to cell type level analysis and missed by TWAS using whole blood. We also develop a cell type aware drug repurposing pipeline, which leverages EXPRESSO results to identify drug compounds that can reverse disease gene expressions in relevant cell types. Our results point to multiple drugs with therapeutic potentials, including metformin for type 1 diabetes, and vitamin K for ulcerative colitis.

Elevated serum BAFF in patients with ocular cicatricial pemphigoid

OBJECTIVE

The efficiency of B-cell depletion therapy for severe ocular cicatricial pemphigoid (OCP) highlights the key role of B lymphocytes in the immunopathogenesis of OCP. B-cell activating factor (BAFF) is a potent B-cell growth factor and costimulator of immunoglobulin production. Elevated serum BAFF is associated with systemic autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis and bullous pemphigoid. We hypothesize that serum BAFF levels are also increased in patients with OCP.

METHODS

Sera were collected from 30 patients with new-onset active OCP, 9 with disease in remission, 10 with OCP relapse, and 15 healthy control individuals. An enzyme-linked immunosorbent assay was performed to measure the concentration of serum BAFF.

RESULTS

BAFF was significantly higher in patients with new-onset active OCP (700.8 ± 181.8 pg/mL) than in healthy control individuals (564.1 ± 133.2 pg/mL; p = 0.014). No significant difference was found between patients with OCP in remission (585.4 ± 216.2 pg/mL) and healthy control individuals. Patients with disease relapse treated with rituximab had an extremely high concentration of BAFF (1721.9 ± 790.8 pg/mL). Longitudinal analysis of serum BAFF from 6 patients showed that BAFF decreased as the disease went from new onset (895.0 ± 240.8 pg/mL) to remission (625.4 ± 199.8 pg/mL; p = 0.003).

CONCLUSIONS

BAFF is involved in the active inflammation of OCP. Targeting BAFF with an antagonist may be therapeutically beneficial for patients with refractory OCP, especially those resistant to rituximab.

Effect of DMARDs on the immunogenicity of vaccines

Vaccines are important for protecting individuals at increased risk of severe infections, including patients undergoing DMARD therapy. However, DMARD therapy can also compromise the immune system, leading to impaired responses to vaccination. This Review focuses on the impact of DMARDs on influenza and SARS-CoV-2 vaccinations, as such vaccines have been investigated most thoroughly. Various data suggest that B cell depletion therapy, mycophenolate mofetil, cyclophosphamide, azathioprine and abatacept substantially reduce the immunogenicity of these vaccines. However, the effects of glucocorticoids, methotrexate, TNF inhibitors and JAK inhibitors on vaccine responses remain unclear and could depend on the dosage and type of vaccination. Vaccination is aimed at initiating robust humoral and cellular vaccine responses, which requires efficient interactions between antigen-presenting cells, T cells and B cells. DMARDs impair these cells in different ways and to different degrees, such as the prevention of antigen-presenting cell maturation, alteration of T cell differentiation and selective inhibition of B cell subsets, thus inhibiting processes that are necessary for an effective vaccine response. Innovative modified vaccination strategies are needed to improve vaccination responses in patients undergoing DMARD therapy and to protect these patients from the severe outcomes of infectious diseases.

Circulating interleukin-39 as a potential biomarker for rheumatoid arthritis diagnosis

BACKGROUND

Imbalances in cytokine networks have been shown to be a possible cause of rheumatoid arthritis (RA). The interleukin (IL)-12 family is involved in the pathogenesis of autoimmune diseases including RA, while IL-39 is a newly discovered member of the IL-12 family, although its role in RA remains unclear. The purpose of the present study was to detect the expression of IL-39 in the sera of patients with RA and its relationship with RA activity.

METHODS

We recruited 46 patients with RA and 35 healthy controls at Ningbo Sixth Hospital. Blood samples were collected for biochemical analysis, and disease activity scores of 28 joints based on C-reactive protein were monitored. Serum concentrations of IL-39 were determined using an enzyme-linked immunosorbent assay. The Pearson correlation test was used to analyze the association between serum IL-39 levels and clinical indicators.

RESULTS

Serum levels of IL-39 were significantly higher in patients with RA compared with healthy controls (p < 0.0001). IL-39 levels positively correlated with rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), and IgM; RF positively correlated with ESR. Receiver operating characteristic curve analysis showed that IL-39 has diagnostic value for RA (p < 0.0001).

CONCLUSIONS

The significant increase of IL-39 levels in serum of patients with RA and its positive correlation with clinical indicators suggest that IL-39 may serve as biomarker for the diagnosis of RA.

Impact of methotrexate treatment on vaccines immunogenicity in adult rheumatological patients - Lessons learned from the COVID-19 pandemic

Despite the development of new biological and synthetic targeted therapies, methotrexate remains one of the most commonly used immunomodulatory drugs in rheumatology. However, its effect on the immunogenicity of vaccines has been studied only to a limited extent until recently, resulting in the lack of clear guidelines on the use of methotrexate during vaccination. Significant progress was made during the COVID-19 pandemic due to the dynamic development of research on vaccines, including patients with autoimmune inflammatory rheumatic diseases. In the following literature review, we present a summary of what we know so far on the impact of methotrexate on post-vaccination response in adult rheumatology patients, taking into account the lessons learned from the COVID-19 pandemic. Studies on the effect of methotrexate on the immunogenicity of influenza, pneumococcal, herpes zoster, tetanus/diphtheria/pertussis, hepatitis A, yellow fever, and COVID-19 vaccines are described in detail, including the effect of methotrexate on the humoral and cellular response of individual vaccines. The available evidence for recommendations for withholding methotrexate in the post-vaccination period is presented. Lastly, an overview of potential immunological mechanisms through which MTX modulates the immunogenicity of vaccinations is also provided.

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.

Improvement of humoral immunity by repeated dose-intensified COVID-19 vaccinations in primary non- to low-responders and B cell deficient rheumatic disease patients

OBJECTIVE

To determine whether repeated, dose-intensified mRNA vaccinations against COVID-19 increase humoral immunity in previously low-responding patients with autoimmune rheumatic diseases (AIRD), including rituximab-treated and B cell depleted patients.

METHODS

Of 308 AIRD patients receiving basic immunization, 98 had a low serological response against SARS-CoV-2 with a neutralizing capacity of < 70% using surrogate neutralization assay. 38 patients received a third vaccination with 30 μg BNT162b2 16 weeks after second vaccination. If neutralizing serum capacity was below 70% four weeks after the last vaccination, then the fourth vaccination (n = 19) and the fifth (n = 4) vaccination with 100 μg mRNA-1273 took place eight weeks after the last vaccination.

RESULTS

Each of the three booster vaccinations resulted in a significant increase of mean serum neutralizing capacity (3rd: Δ = 42%, p < 0.001; 4th: Δ = 19%, p = 0.049 and 5th: Δ = 51%, p = 0.043) and produced a significant proportion of high-responders (3rd: 34%; 4th: 32% and 5th: 75%). Low B cell counts (p = 0.047), lower previous antibody response (p < 0.001) and rituximab therapy (p = 0.021) were negatively associated with successful response to the third but not to the fourth vaccination. Remarkably, substantial increases in neutralization capacity of up to 99% were observed after repeated vaccinations in B cell depleted patients.

CONCLUSION

AIRD patients with low humoral response benefited from up to three repeated dose-intensified mRNA booster vaccinations - despite low B cell count and previous rituximab therapy. Each additional vaccination substantially reduced the number of low-responding, vulnerable patients.

Effects of temporarily suspending low-dose methotrexate treatment for 2 weeks after SARS-CoV-2 vaccine booster on vaccine response in immunosuppressed adults with inflammatory conditions: protocol for a multicentre randomised controlled trial and nested mechanistic substudy (Vaccine Response On/Off Methotrexate (VROOM) study)

INTRODUCTION

It is unknown if a temporary break in long-term immune-suppressive treatment after vaccination against COVID-19 improves vaccine response. The objective of this study was to evaluate if a 2-week interruption in low-dose weekly methotrexate treatment after SARS-CoV-2 vaccine boosters enhances the immune response compared with continuing treatment in adults with autoimmune inflammatory conditions.

METHODS AND ANALYSIS

An open-label, pragmatic, prospective, parallel group, randomised controlled superiority trial with internal feasibility assessment and nested mechanistic substudy will be conducted in rheumatology and dermatology clinics in approximately 25 UK hospitals. The sample size is 560, randomised 1:1 to intervention and usual care arms. The main outcome measure is anti-spike receptor-binding domain (RBD) antibody level, collected at prebooster (baseline), 4 weeks (primary outcome) and 12 weeks (secondary outcome) post booster vaccination. Other secondary outcome measures are patient global assessments of disease activity, disease flares and their treatment, EuroQol 5- dimention 5-level (EQ-5D-5L), self-reported adherence with advice to interrupt or continue methotrexate, neutralising antibody titre against SARS-CoV-2 (mechanistic substudy) and oral methotrexate biochemical adherence (mechanistic substudy). Analysis of B-cell memory and T-cell responses at baseline and weeks 4 and 12 will be investigated subject to obtaining additional funding. The principal analysis will be performed on the groups as randomised (ie, intention to treat). The difference between the study arms in anti-spike RBD antibody level will be estimated using mixed effects model, allowing for repeated measures clustered within participants. The models will be adjusted for randomisation factors and prior SARS-CoV-2 infection status.

ETHICS AND DISSEMINATION

This study was approved by the Leeds West Research Ethics Committee and Health Research Authority (REC reference: 21/HRA/3483, IRAS 303827). Participants will be required to give written informed consent before taking part in the trial. Dissemination will be via peer review publications, newsletters and conferences. Results will be communicated to policymakers.

TRIAL REGISTRATION NUMBER

ISRCTN11442263.

Juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is an umbrella term for arthritis of unknown origin, lasting for >6 weeks with onset before 16 years of age. JIA is the most common chronic inflammatory rheumatic condition of childhood. According to the International League Against Rheumatism (ILAR) classification, seven mutually exclusive categories of JIA exist based on disease manifestations during the first 6 months of disease. Although the ILAR classification has been useful to foster research, it has been criticized mainly as it does not distinguish those forms of chronic arthritis observed in adults and in children from those that may be unique to childhood. Hence, efforts to provide a new evidence-based classification are ongoing. Similar to arthritis observed in adults, pathogenesis involves autoimmune and autoinflammatory mechanisms. The field has witnessed a remarkable improvement in therapeutic possibilities of JIA owing to the availability of new potent drugs and the possibility to perform controlled trials with support from legislative interventions and large networks availability. The goal of drug therapy in JIA is to rapidly reduce disease activity to inactive disease or clinical remission, minimize drug side effects and achieve a quality of life comparable to that of healthy peers. As JIA can influence all aspects of a child's and their family's life, researchers increasingly recognize improvement of health-related quality of life as a key treatment goal.

Mechanistic insights into the role of B cells in rheumatoid arthritis

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

BAFF predicts immunogenicity in older patients with rheumatoid arthritis treated with TNF inhibitors

Immunogenicity related to treatment with TNF inhibitors (TNFi) is one of the causes for the decreased attainment of clinical response in patients with rheumatoid arthritis (RA). The B-cell activating factor (BAFF) may be playing a role in the development of immunogenicity. The objective of this study was to analyse the association of baseline concentration of serum B-cell activating factor (BAFF) with immunogenicity after 6 months of TNFi treatment. A total of 127 patients with RA starting a TNFi (infliximab, adalimumab, certolizumab pegol or golimumab) were followed-up for 6 months. Serum samples were obtained at baseline and at 6 months and anti-drug antibody (ADA) and BAFF concentrations were measured. Logistic regression models were employed in order to analyse the association between BAFF concentrations and immunogenicity. Receiver operating characteristic analysis was performed to determine the BAFF concentrations with a greater likelihood of showing immunogenicity association. At 6 months, 31 patients (24%) developed ADA. A significant interaction between the age and baseline BAFF concentration was found for the development of ADA (Wald chi-square value = 5.30; p = 0.02); therefore, subsequent results were stratified according to mean age (≤ / > 55 years). Baseline serum BAFF concentration was independently associated with ADA development only in patients over 55 years (OR = 1.51; 95% CI 1.03–2.21). Baseline serum BAFF ≥ 1034 pg/mL predicted the presence of ADA at 6 months (AUC = 0.81; 95% confidence interval (CI) 0.69–0.93; p = 0.001; positive likelihood ratio = 3.7). In conclusion, our results suggest that the association of BAFF concentration and immunogenicity depends on the patient’s age. Baseline serum BAFF concentration predicts the presence of ADA within 6 months of TNFi therapy in older patients with RA.

Effects of Chemotherapy Agents on Circulating Leukocyte Populations: Potential Implications for the Success of CAR-T Cell Therapies

Simple Summary

CAR-T cell therapy is a new approach to cancer treatment that is based on manipulating a patient’s own T cells such that they become able to seek and destroy cancer cells in a highly specific manner. This approach is showing remarkable efficacy in treating some types of blood cancers but so far has been much less effective against solid cancers. Here, we review the diverse effects of chemotherapy agents on circulating leukocyte populations and find that, despite some negative effects over the short term, chemotherapy can favourably modulate the immune systems of cancer patients over the longer term. Since blood is the starting material for CAR-T cell production, we propose that these effects could significantly influence the success of manufacturing, and anti-cancer activity, of CAR-T cells. Thus, if timed correctly, chemotherapy-induced changes to circulating immune cells could allow CAR-T cells to unleash more effective anti-tumour responses.

Abstract

Adoptive T-cell therapy using autologous T cells genetically modified to express cancer-specific chimeric antigen receptors (CAR) has emerged as a novel approach for cancer treatment. CAR-T cell therapy has been approved in several major jurisdictions for treating refractory or relapsed cases of B-cell precursor acute lymphoblastic leukaemia and diffuse large B-cell lymphoma. However, in solid cancer patients, several clinical studies of CAR-T cell therapy have demonstrated minimal therapeutic effects, thus encouraging interest in better integrating CAR-T cells with other treatments such as conventional cytotoxic chemotherapy. Increasing evidence shows that not only do chemotherapy drugs have tumoricidal effects, but also significantly modulate the immune system. Here, we discuss immunomodulatory effects of chemotherapy drugs on circulating leukocyte populations, including their ability to enhance cytotoxic effects and preserve the frequency of CD8⁺ T cells and to deplete immunosuppressive populations including regulatory T cells and myeloid-derived suppressor cells. By modulating the abundance and phenotype of leukocytes in the blood (the ‘raw material’ for CAR-T cell manufacturing), we propose that prior chemotherapy could facilitate production of the most effective CAR-T cell products. Further research is required to directly test this concept and identify strategies for the optimal integration of CAR-T cell therapies with cytotoxic chemotherapy for solid cancers.

Impact of Biological Therapies on the Immune Response after Pneumococcal Vaccination in Patients with Autoimmune Inflammatory Diseases

Patients with different autoimmune inflammatory diseases (AIID) on biological therapy are at risk of pneumococcal disease. Adults with inflammatory arthropathies, connective tissue diseases, psoriasis, or inflammatory bowel disease on biological therapy such as anti-TNFα, rituximab, tocilizumab, abatacept, or anakinra were included in this study. Patients completed a protocol combining the pneumococcal vaccines PCV13 and PPV23. Immune response against pneumococcal serotypes 1, 3, 7F, 14, 19A, and 19F were assessed evaluating functional antibodies by an opsonophagocytosis killing assay (OPKA). In this study, 182 patients with AIID completed the sequential vaccination protocol. Patients on etanercept tended to achieve OPKA titers against a larger number of serotypes than the rest of patients on other biological therapies, while adalimumab was associated to a lower number of serotypes with OPKA titers. Rituximab was not associated with a worse response when compared with the rest of biological agents. Not glucocorticoids, nor synthetic disease-modifying antirheumatic drugs, interfered with the immune response. OPKA titers against serotype 3 which is one of the most prevalent, was obtained in 44% of patients, increasing up to 58% in those on etanercept. Hence, almost 50% of patients on biological therapy achieved functional antibodies after the administration of a complete pneumococcal vaccination protocol.

Tdap booster to adolescents with juvenile idiopathic arthritis on and off anti-TNF agents is safe and immunogenic

INTRODUCTION

The response to vaccines in juvenile idiopathic arthritis (JIA) patients on and off anti-tumor necrosis factor (anti-TNF) agents remains highly discussed. There are no published studies on the immune response following a Tdap booster dose in JIA patients so far.

OBJECTIVE

To evaluate the immune response and safety after a Tdap booster in JIA patients and in healthy adolescents.

METHODS

Nineteen adolescents with JIA according to the ILAR criteria on anti-TNF medication, 19 adolescents with JIA off anti-TNF medication, and 27 healthy adolescents (control group) were compared after a Tdap booster. Adverse events and disease activity were evaluated. Lymphocyte immunophenotyping was performed by flow cytometry. Tetanus, diphtheria and pertussis toxin antibodies were assessed by ELISA; whole blood was stimulated with whole-cell pertussis, and supernatants were assessed for cytokines by xMAP.

RESULTS

The three groups showed a similar frequency of adverse events. There was no disease reactivation after the Tdap booster. Tetanus, diphtheria and pertussis antibodies showed a significant response when D0 and D14 concentrations were compared in both JIA groups and controls. Over time, a different pattern of response to the Tdap booster was observed among the groups for tetanus antibodies (p = 0.005) but not for diphtheria and pertussis antibodies. In contrast to the protection attained for tetanus and diphtheria, in the three groups, not all individuals showed pertussis seroconversion at either D14 or D28. In addition, the seroconversion of three subjects with JIA on anti-TNF medication was not maintained at D28. JIA patients off anti-TNF showed a higher percentage of naive CD8 + T cells (p = 0.007) and central memory CD8 + cells (p = 0.003) and a lower percentage of effector CD8 + T cells (p = 0.003) and NK cell numbers (p = 0.018) than the control group. The JIA group off anti-TNF medication had fewer B lymphocytes than both the JIA group on anti-TNF medication and the control group (p = 0.016). Cellular immunity to Bordetella pertussis showed that IFNγ levels were significantly lower in both JIA groups than in the control group (p = 0.003), IL10 levels were higher in the JIA off anti-TNF group (p = 0.009), IL17A and IL5 levels were lower in the JIA on anti-TNF group than in the control group (p = 0.018 and p = 0.016, respectively); however, an increase in IFNγ (p = 0.008), IL17A (p = 0.030) and TNFα (p = 0.041) levels was observed at D14 in both patient groups. Both JIA groups showed higher levels of IL21 than the control group (p = 0.023).

CONCLUSION

We conclude that individuals with JIA on or off anti-TNF agents showed a good response to a booster dose for the three antigens studied in the absence of major adverse events and without the reactivation of the disease.

B cells from Patients with Rheumatoid Arthritis Show Conserved CD39-Mediated Regulatory Function and increased CD39 Expression After Positive Response to Therapy

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by progressive joint destruction associated with increased pro-inflammatory mediators. In inflammatory microenvironments, exogenous ATP (eATP) is hydrolyzed to adenosine, which exerts immunosuppressive effects, by the consecutive action of the ectonucleotidases CD39 and CD73. Mature B cells constitutively express both ectonucleotidases, converting these cells to potential suppressors. Here, we assessed CD39 and CD73 expression on B cells from treated or untreated patients with RA. Neither the frequency of CD73⁺CD39⁺ and CD73^-CD39⁺ B cell subsets nor the levels of CD73 and CD39 expression on B cells from untreated or treated RA patients showed significant changes in comparison to healthy controls (HC). CpG+IL-2-stimulated B cells from HC or untreated RA patients increased their CD39 expression, and suppressed CD4⁺ and CD8⁺ T cell proliferation and intracellular TNF-production. A CD39 inhibitor significantly restored proliferation and TNF-producing capacity in CD4⁺ T cells, but not in CD8⁺ T cells, from HC and untreated RA patients, indicating that B cells from untreated RA patients conserved CD39-mediated regulatory function. Good responder patients to therapy (R-RA) exhibited an increased CD39 but not CD73 expression on B cells after treatment, while most of the non-responder (NR) patients showed a reduction in ectoenzyme expression. The positive changes of CD39 expression on B cells exhibited a negative correlation with disease activity and rheumatoid factor levels. Our results suggest modulating the ectoenzymes/ADO pathway as a potential therapy target for improving the course of RA.

Potential of B-cell-targeting therapy in overcoming multidrug resistance and tissue invasiveness associated with P-glycoprotein expressing-B cell compartments

Rheumatoid arthritis (RA) is a systemic autoimmune mediated inflammatory disease characterized by progressive joint damage and extra-articular organ manifestations. Among the effector pathways and cells involved in the development of RA, activated B cells play a pivotal role in the pathological process of RA. P-glycoprotein (P-gp), a member of ATP-binding cassette transporters, is induced on the cell membrane by certain stimuli. P-gp transports various drugs from the cytoplasm to the cell exterior, resulting in the development of drug resistance. P-gp expression on B cells appears in patients with RA as the disease activity increases, and treatment of these patients' results in modification of over-expression of P-gp on activated B cells. Evidence suggests that P-gp expressing-activated B cells play important roles in the pathogenesis and treatment resistance in RA through the efflux of intracellular drugs and progression of infiltration in inflammatory lesions. Therapies designed to target activated B cells might overcome refractory RA. Identification of the subsets of peripheral activated B cells that express P-gp in RA patients might help the selection of suitable treatment strategy.

Whole Transcriptome Analysis Reveals Heterogeneity in B Cell Memory Populations in Patients With Juvenile Idiopathic Arthritis-Associated Uveitis

Purpose

Patients with juvenile idiopathic arthritis (JIA) are prone to developing chronic anterior uveitis (JIA-U+). Although several risk factors for JIA-U+ have been identified, the underlying etiology is poorly understood. Histopathological studies demonstrate B cell infiltrates in eye tissues of patients with JIA-U+.

Methods

We performed transcriptome profiling of peripheral blood CD19-positive B cells taken from 14 cases with JIA-U+, 13 JIA cases without uveitis (JIA-U-), and five healthy controls. Deconvolution-based estimation was used to determine the immune cell fractions for each sample.

Results

Deconvolution results revealed that naive B cells made up on average 71% of the CD19-positive cell fractions analyzed. Differential expression analysis identified 614 differentially expressed genes (DEGs) between the groups at nominal significance and six genes at a false discovery rate of 5% (FDR < 0.05). Head-to-head comparison of all JIA-U- versus JIA-U+ revealed no DEGs in the CD19+ B cell pool (FDR < 0.05). However, principal component analysis based on a panel of key genes for B cell subsets revealed that JIA-U+ cases bifurcate into distinct clusters, characterized by markedly disparate expression for genes associated with specific memory B cell populations. CIBERSORT analysis of the overall transcriptome of the new uveitis cluster identified an increased proportion of memory B cells.

Conclusion

These data show that JIA-U- and JIA-U+ have a globally similar transcriptome considering the global peripheral CD19-positive B cell pool. However, heterogeneity in B cell memory genes among cases with uveitis suggests a role for specific memory B cell subsets in the etiology of JIA-U+.

Targeting FcRn for immunomodulation: Benefits, risks, and practical considerations

The neonatal fragment crystallizable (Fc) receptor (FcRn) functions as a recycling mechanism to prevent degradation and extend the half-life of IgG and albumin in the circulation. Several FcRn inhibitors selectively targeting IgG recycling are now moving rapidly toward clinical practice in neurology and hematology. These molecules accelerate the destruction of IgG, reducing pathogenic IgG and IgG immune complexes, with no anticipated effects on IgA, IgM, IgE, complement, plasma cells, B cells, or other cells of the innate or adaptive immune systems. FcRn inhibitors have potential for future use in a much wider variety of antibody-mediated autoimmune diseases. Given the imminent clinical use, potential for broader utility, and novel mechanism of action of FcRn inhibitors, here we review data from 4 main sources: (a) currently available activity, safety, and mechanism-of-action data from clinical trials of FcRn inhibitors; (b) other procedures and treatments that also remove IgG (plasma donation, plasma exchange, immunoadsorption); (c) diseases resulting in loss of IgG; and (d) primary immunodeficiencies with potential mechanistic similarities to those induced by FcRn inhibitors. These data have been evaluated to provide practical considerations for the assessment, monitoring, and reduction of any potential infection risk associated with FcRn inhibition, in addition to highlighting areas for future research.

Benefits of Prophylactic Short-Course Immune Tolerance Induction in Patients With Infantile Pompe Disease: Demonstration of Long-Term Safety and Efficacy in an Expanded Cohort

Immune tolerance induction (ITI) with a short-course of rituximab, methotrexate, and/or IVIG in the enzyme replacement therapy (ERT)-naïve setting has prolonged survival and improved clinical outcomes in patients with infantile Pompe disease (IPD) lacking endogenous acid-alpha glucosidase (GAA), known as cross-reactive immunologic material (CRIM)-negative. In the context of cancer therapy, rituximab administration results in sustained B-cell depletion in 83% of patients for up to 26–39 weeks with B-cell reconstitution beginning at approximately 26 weeks post-treatment. The impact of rituximab on serum immunoglobulin levels is not well studied, available data suggest that rituximab can cause persistently low immunoglobulin levels and adversely impact vaccine responses. Data on a cohort of IPD patients who received a short-course of ITI with rituximab, methotrexate, and IVIG in the ERT-naïve setting and had ≥6 months of follow-up were retrospectively studied. B-cell quantitation, ANC, AST, ALT, immunization history, and vaccine titers after B-cell reconstitution were reviewed. Data were collected for 34 IPD patients (25 CRIM-negative and 9 CRIM-positive) with a median age at ERT initiation of 3.5 months (0.1–11.0 months). B-cell reconstitution, as measured by normalization of CD19%, was seen in all patients (n = 33) at a median time of 17 weeks range (11–55 weeks) post-rituximab. All maintained normal CD19% with the longest follow-up being 248 weeks post-rituximab. 30/34 (88%) maintained negative/low anti-rhGAA antibody titers, even with complete B-cell reconstitution. Infections during immunosuppression were reported in five CRIM-negative IPD patients, all resolved satisfactorily on antibiotics. There were no serious sequelae or deaths. Of the 31 evaluable patients, 27 were up to date on age-appropriate immunizations. Vaccine titers were available for 12 patients after B-cell reconstitution and adequate humoral response was observed in all except an inadequate response to the Pneumococcal vaccine (n = 2). These data show the benefits of short-course prophylactic ITI in IPD both in terms of safety and efficacy. Data presented here are from the youngest cohort of patients treated with rituximab and expands the evidence of its safety in the pediatric population.

Early Prediction of Clinical Response to Etanercept Treatment in Juvenile Idiopathic Arthritis Using Machine Learning

Background and Aims

At present, there is a lack of simple and reliable model for early prediction of the efficacy of etanercept in the treatment of juvenile idiopathic arthritis (JIA). This study aimed to generate and validate prediction models of etanercept efficacy in patients with JIA before administration using machine learning algorithms based on electronic medical record (EMR).

Materials and Methods

EMR data of 87 JIA patients treated with etanercept between January 2011 and December 2018 were collected retrospectively. The response of etanercept was evaluated by using DAS44/ESR-3 simplified standard. The stepwise forward and backward method based on information gain was applied to select features. Five machine learning algorithms, including Extreme Gradient Boosting (XGBoost), Random Forest (RF), Gradient Boosting Decision Tree (GBDT), Extremely Random Trees (ET) and Logistic Regression (LR) were used for model generation and validation with fifty-fold stratified cross-validation. EMR data of additional 14 patients were collected for external validation of the model.

Results

Tender joint count (TJC), Time interval, Lymphocyte percentage (LYM), and Weight were screened out and included in the final model. The model generated by the XGBoost algorithm based on the above 4 features had the best predictive performance: sensitivity 75%, specificity 66.67%, accuracy 72.22%, AUC 79.17%, respectively.

Conclusion

A pre-administration model with good prediction performance for etanercept response in JIA was developed using advanced machine learning algorithms. Clinicians and pharmacists can use this simple and accurate model to predict etanercept response of JIA early and avoid treatment failure or adverse effects.

Peripheral Blood Lymphocyte Phenotype Differentiates Secondary Antibody Deficiency in Rheumatic Disease from Primary Antibody Deficiency

The phenotype of primary immunodeficiency disorders (PID), and especially common variable immunodeficiency (CVID), may be dominated by symptoms of autoimmune disorders. Furthermore, autoimmunity may be the first manifestation of PID, frequently preceding infections and the diagnosis of hypogammaglobulinemia, which occurs later on. In this case, distinguishing PID from hypogammaglobulinemia secondary to anti-inflammatory treatment of autoimmunity may become challenging. The aim of this study was to evaluate the diagnostic accuracy of peripheral blood lymphocyte phenotyping in resolving the diagnostic dilemma between primary and secondary hypogammaglobulinemia. Comparison of B and T cell subsets from patients with PID and patients with rheumatic disease, who developed hypogammaglobulinemia as a consequence of anti-inflammatory regimes, revealed significant differences in proportion of naïve B cells, class-switched memory B cells and CD21^low B cells among B cells as well as in CD4⁺ memory T cells and CD4⁺ T follicular cells among CD4⁺ T cells. Identified differences in B cell and T cell subsets, and especially in the proportion of class-switched memory B cells and CD4⁺ T follicular cells, display a considerable diagnostic efficacy in distinguishing PID from secondary hypogammaglobulinemia due to anti-inflammatory regimens for rheumatic disease.

Targeting immunometabolism as an anti-inflammatory strategy

The growing field of immunometabolism has taught us how metabolic cellular reactions and processes not only provide a means to generate ATP and biosynthetic precursors, but are also a way of controlling immunity and inflammation. Metabolic reprogramming of immune cells is essential for both inflammatory as well as anti-inflammatory responses. Four anti-inflammatory therapies, DMF, Metformin, Methotrexate and Rapamycin all work by affecting metabolism and/or regulating or mimicking endogenous metabolites with anti-inflammatory effects. Evidence is emerging for the targeting of specific metabolic events as a strategy to limit inflammation in different contexts. Here we discuss these recent developments and speculate on the prospect of targeting immunometabolism in the effort to develop novel anti-inflammatory therapeutics. As accumulating evidence for roles of an intricate and elaborate network of metabolic processes, including lipid, amino acid and nucleotide metabolism provides key focal points for developing new therapies, we here turn our attention to glycolysis and the TCA cycle to provide examples of how metabolic intermediates and enzymes can provide potential novel therapeutic targets.

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.

General synovitis score and immunologic synovitis score reflect clinical disease activity in patients with advanced stage rheumatoid arthritis

The purpose of this study was to investigate the relationship between clinical disease activity in patients with advanced stage rheumatoid arthritis (RA) on treatment with Disease Modifying Antirheumatic Drugs (DMARDs) and histopathological scores of synovial inflammation. To this end, synovial biopsies of 62 RA patients who underwent surgery for either synovectomy or total joint arthroplasty were assessed by a general synovitis score (GSS) and an immunologic synovitis score (IMSYC). The clinical disease activity index (CDAI) was significantly correlated with both the GSS and the IMSYC (r = 0.65, p = <0.001, r = 0.68, p = <0.001). Compared to patients with moderate and high disease activity, there was a significantly lower expression of T cell (CD3), B cell (CD20) and neutrophil (CD15) markers in synovial tissue of patients with low activity, but similar expression of the macrophage marker CD68. Subgroup analyses revealed no differences between small and large joints, seropositive and seronegative RA and patients with or without prednisolone treatment. However, we found a significantly stronger correlation of CDAI with IMSYC in patients undergoing arthroplasty (r = 0.82) than in patients undergoing synovectomy (r = 0.55). In addition, there was a stronger correlation of CDAI with GSS in patients treated with methotrexate (r = 0.86) than in patients with TNFα blockade (r = 0.55). In summary, the present study demonstrates that the histopathological scores GSS and IMSYC in general reflect clinical disease activity in patients with advanced stage rheumatoid arthritis, but that there is some heterogeneity between subgroups of patients within the cohort. In the future, molecular characterization of synovial inflammatory cell populations, including plasma cell infiltrates, will help to further defined clinically important subtypes of RA and treatment response.

Altered proportions of circulating CXCR5+ helper T cells do not dampen influenza vaccine responses in children with rheumatic disease

Biological therapy options for the treatment of rheumatic disease target molecules that can affect the cross-talk between innate and adaptive immune responses upon vaccination. Influenza vaccination in children with rheumatic disease has been recommended, but there are only sparse data on the quality of vaccine responses from pediatric patients treated with biological therapy. We conducted an influenza vaccine study over 3 consecutive seasons where the antibody response to TIV was evaluated in children with PRD (n = 78), including both non-treated (n = 17) and treated (with methotrexate, TNF-inhibitors with or without methotrexate, or IL-inhibitors, n = 61) children as well as healthy age-matched controls (n = 24). Peripheral B cells, T and NK cell populations, as well as CXCR5+ (follicular) helper T cells (T_FH) and chemokines involved in antibody responses were assessed prior to immunization in the same cohort. Data on disease duration, therapy and data on previous influenza vaccinations were retrieved. The proportion of circulating T_FH cells were significantly lower in non-treated children with PRD compared to treated patients and healthy controls. The significantly lower proportion of T_FH cells was mirrored by a marked significant increase in CXCL13 serum level, the ligand for CXCR5, with higher levels in non-treated children with PRD compared to treated patients and healthy controls. However, the proportion of T_FH cells or CXCL13 level at the time of vaccination was not a predictor of the antibody response to TIV in this cohort of children. Children with PRD had an overall similar response to TIV as healthy children. Although not significant, children treated with TNF-inhibitors differed as a few children remained seronegative towards H3N2- and influenza B viruses after immunization. Our data show that children with PRD respond to TIV as healthy children. Furthermore, plasma CXCL13 levels did not correlate to the proportion of T_FH cells in blood prior to immunisation, or to antibody responses following immunization.

Anti-TNF Therapy in Spondyloarthritis and Related Diseases, Impact on the Immune System and Prediction of Treatment Responses

Immune-mediated inflammatory diseases (IMIDs), such as spondyloarthritis (SpA), psoriasis, Crohn's disease (CD), and rheumatoid arthritis (RA) remain challenging illnesses. They often strike at a young age and cause lifelong morbidity, representing a considerable burden for the affected individuals and society. Pioneering studies have revealed the presence of a TNF-dependent proinflammatory cytokine cascade in several IMIDs, and the introduction of anti-TNF therapy 20 years ago has proven effective to reduce inflammation and clinical symptoms in RA, SpA, and other IMID, providing unprecedented clinical benefits and a valid alternative in case of failure or intolerable adverse effects of conventional disease-modifying antirheumatic drugs (DMARDs, for RA) or non-steroidal anti-inflammatory drugs (NSAIDs, for SpA). However, our understanding of how TNF inhibitors (TNFi) affect the immune system in patients is limited. This question is relevant because anti-TNF therapy has been associated with infectious complications. Furthermore, clinical efficacy of TNFi is limited by a high rate of non-responsiveness (30–40%) in RA, SpA, and other IMID, exposing a substantial fraction of patients to side-effects without clinical benefit. Despite the extensive use of TNFi, it is still not possible to determine which patients will respond to TNFi before treatment initiation. The recent introduction of antibodies blocking IL-17 has expanded the therapeutic options for SpA, as well as psoriasis and psoriatic arthritis. It is therefore essential to develop tools to guide treatment decisions for patients affected by SpA and other IMID, both to optimize clinical care and contain health care costs. After a brief overview of the biology of TNF, its receptors and currently used TNFi in the clinics, we summarize the progress that has been made to increase our understanding of the action of TNFi on the immune system in patients. We then summarize efforts dedicated to identify biomarkers that can predict treatment responses to TNFi and we conclude with a section dedicated to the recently introduced inhibitors of IL-17A and IL-23 in SpA and related diseases. The focus of this review is on SpA, however, we also refer to RA on topics for which only limited information is available on SpA in the literature.

Peripheral-blood b-cell subset disturbances in inflammatory joint diseases induced by Tropheryma whipplei

Objective

To look for abnormalities in circulating B-cell subsets in patients with rheumatic symptoms of Whipple’s disease (WD).

Method

Consecutive patients seen between 2010 and 2016 for suspected inflammatory joint disease were identified retrospectively. Results of standardized immunological and serological tests and of peripheral-blood B-cell and T-cell subset analysis by flow cytometry were collected. Patients with criteria suggesting WD underwent PCR testing for Tropheryma whipplei, and those with diagnosis of WD (cases) were compared to those without diagnosis (controls). We used ROC curve analysis to evaluate the diagnostic value of flow cytometry findings for WD.

Results

Among 2917 patients seen for suspected inflammatory joint disease, 121 had suspected WD, including 9 (9/121, 7.4%) confirmed WD. Proportions of T cells and NK cells were similar between suspected and confirmed WD, whereas cases had a lower proportion of circulating memory B cells (IgD^-CD38^low, 18.0%±9.7% vs. 26.0%±14.2%, P = 0.041) and higher ratio of activated B cells over memory B cells (4.4±2.0 vs. 2.9±2.2, P = 0.023). Among peripheral-blood B-cells, the proportion of IgD+CD27- naive B cells was higher (66.2%±18.2% vs. 54.6%±18.4%, P = 0.047) and that of IgD-CD27+ switched memory B cells lower (13.3%±5.7% vs. 21.4%±11.9%, P = 0.023), in cases vs. controls. The criterion with the best diagnostic performance was a proportion of IgD+CD27- naive B cells above 70.5%, which had 73% sensitivity and 80% specificity.

Conclusion

Our study provides data on peripheral-blood B-cell disturbances that may have implications for the diagnosis and pathogenetic understanding of WD.

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.

IgG Anti-ghrelin Immune Complexes Are Increased in Rheumatoid Arthritis Patients Under Biologic Therapy and Are Related to Clinical and Metabolic Markers

Rheumatoid arthritis (RA) is a systemic autoimmune disease associated with increased risk of cardiovascular disease and metabolic alterations. The mechanisms underlying these alterations remain unclear. Ghrelin is a gastrointestinal hormone with potent effects on food intake, body weight, metabolism, and immune response. Recent studies reported the presence of anti-ghrelin autoantibodies in healthy subjects and the levels and affinity of these autoantibodies were altered in anorectic and obese individuals. In this cross-sectional study we analyzed anti-ghrelin autoantibodies in RA patients and evaluated its relationship with clinical, body-composition and metabolic parameters. Clinical measurements of RA patients included the disease activity score-28 (DAS-28), inflammatory biomarkers, autoantibodies (RF and anti-CCP), body composition, glucose and lipid profile. Serum ghrelin levels were measured by enzyme-linked immunosorbent assay (ELISA). Free and total anti-ghrelin autoantibodies quantification (IgG and IgA isotypes) was performed by in-house ELISA. RA patients had lower IgG anti-ghrelin autoantibodies levels and higher immune complexes percentage (IgG+ghrelin) compared to the control group, while the IgA anti-ghrelin autoantibodies showed no significant differences. In the bivariate analysis, the percentage of IgG anti-ghrelin immune complexes positively correlated with BMI and ghrelin whereas in the multivariate regression model, the variables associated were DAS-28, body weight, visceral fat, LDL-C and TG (R ² = 0.72). The percentage of IgA anti-ghrelin immune complexes positively correlated with RF and anti-CCP and the multivariate regression model showed an association with RF and body fat percentage (R ² = 0.22). Our study shows an increased percentage of IgG anti-ghrelin immune complexes in RA patients despite ghrelin levels were similar in both groups, suggesting an increase in the affinity of these autoantibodies toward ghrelin. The associations found in the multiple regression analysis for anti-ghrelin immune complexes support the previously reported functions of these natural autoantibodies as carriers and modulators of the stability and physiological effect of the hormone. However, in RA both the disease activity and the RF appear to influence the formation of these anti-ghrelin immune complexes.

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.

CD19+CD24hiCD38hi B Cells Are Expanded in Juvenile Dermatomyositis and Exhibit a Pro-Inflammatory Phenotype After Activation Through Toll-Like Receptor 7 and Interferon-α

Juvenile dermatomyositis (JDM) is a rare form of childhood autoimmune myositis that presents with proximal muscle weakness and skin rash. B cells are strongly implicated in the pathogenesis of the disease, but the underlying mechanisms are unknown. Therefore, the main objective of our study was to investigate mechanisms driving B cell lymphocytosis and define pathological features of B cells in JDM patients. Patients were recruited through the UK JDM Cohort and Biomarker study. Peripheral blood B cell subpopulations were immunophenotyped by flow cytometry. The results identified that immature transitional B cells were significantly expanded in active JDM, actively dividing, and correlated positively with disease activity. Protein and RNAseq analysis revealed high interferon alpha (IFNα) and TLR7-pathway signatures pre-treatment. Stimulation of B cells through TLR7/8 promoted both IL-10 and IL-6 production in controls but failed to induce IL-10 in JDM patient cells. Interrogation of the CD40–CD40L pathway (known to induce B cell IL-10 and IL-6) revealed similar expression of IL-10 and IL-6 in B cells cultured with CD40L from both JDM patients and controls. In conclusion, JDM patients with active disease have a significantly expanded immature transitional B cell population which correlated with the type I IFN signature. Activation through TLR7 and IFNα may drive the expansion of immature transitional B cells in JDM and skew the cells toward a pro-inflammatory phenotype.

Targeting B Cells and Plasma Cells in Autoimmune Diseases

Success with B cell depletion using rituximab has proven the concept that B lineage cells represent a valid target for the treatment of autoimmune diseases, and has promoted the development of other B cell targeting agents. Present data confirm that B cell depletion is beneficial in various autoimmune disorders and also show that it can worsen the disease course in some patients. These findings suggest that B lineage cells not only produce pathogenic autoantibodies, but also significantly contribute to the regulation of inflammation. In this review, we will discuss the multiple pro- and anti-inflammatory roles of B lineage cells play in autoimmune diseases, in the context of recent findings using B lineage targeting therapies.

Switched Memory B Cells Are Increased in Oligoarticular and Polyarticular Juvenile Idiopathic Arthritis and Their Change Over Time Is Related to Response to Tumor Necrosis Factor Inhibitors

OBJECTIVE

To investigate whether abnormalities in B cell subsets in patients with juvenile idiopathic arthritis (JIA) correlate with clinical features and response to treatment.

METHODS

A total of 109 patients diagnosed as having oligoarticular JIA or polyarticular JIA were enrolled in the study. B cell subsets in peripheral blood and synovial fluid were analyzed by flow cytometry.

RESULTS

Switched memory B cells were significantly increased in patients compared to age-matched healthy controls (P < 0.0001). When patients were divided according to age at onset of JIA, in patients with early-onset disease (presenting before age 6 years) the expansion in switched memory B cells was more pronounced than that in patients with late-onset disease and persisted throughout the disease course. In longitudinal studies, during methotrexate (MTX) treatment, regardless of the presence or absence of active disease, the number of switched memory B cells increased significantly (median change from baseline 36% [interquartile range {IQR} 15, 66]). During treatment with MTX plus tumor necrosis factor inhibitors (TNFi), in patients maintaining disease remission, the increase in switched memory B cells was significantly lower than that in patients who experienced active disease (median change from baseline 4% [IQR -6, 32] versus 41% [IQR 11, 73]; P = 0.004). The yearly rate of increases in switched memory B cells was 1.5% in healthy controls, 1.2% in patients who maintained remission during treatment with MTX plus TNFi, 4.7% in patients who experienced active disease during treatment with MTX plus TNFi, and ~4% in patients treated with MTX alone.

CONCLUSION

Switched memory B cells expand during the disease course at a faster rate in JIA patients than in healthy children. This increase is more evident in patients with early-onset JIA. TNFi treatment inhibits this increase in patients who achieve and maintain remission, but not in those with active disease.

Decreased production of class-switched antibodies in neonatal B cells is associated with increased expression of miR-181b

The increased susceptibility to infections of neonates is caused by an immaturity of the immune system as a result of both qualitative and quantitative differences between neonatal and adult immune cells. With respect to B cells, neonatal antibody responses are known to be decreased. Accountable for this is an altered composition of the neonatal B cell compartment towards more immature B cells. However, it remains unclear whether the functionality of individual neonatal B cell subsets is altered as well. In the current study we therefore compared phenotypical and functional characteristics of corresponding neonatal and adult B cell subpopulations. No phenotypic differences could be identified with the exception of higher IgM expression in neonatal B cells. Functional analysis revealed differences in proliferation, survival, and B cell receptor signaling. Most importantly, neonatal B cells showed severely impaired class-switch recombination (CSR) to IgG and IgA. This was associated with increased expression of miR-181b in neonatal B cells. Deficiency of miR-181b resulted in increased CSR. With this, our results highlight intrinsic differences that contribute to weaker B cell antibody responses in newborns.

CP-25, a Novel Anti-inflammatory and Immunomodulatory Drug, Inhibits the Functions of Activated Human B Cells through Regulating BAFF and TNF-alpha Signaling and Comparative Efficacy with Biological Agents

Paeoniflorin-6′-O-benzene sulfonate (code: CP-25) was the chemistry structural modifications of Paeoniflorin (Pae). CP-25 inhibited B cells proliferation stimulated by B cell activating factor belonging to the TNF family (BAFF) or Tumor necrosis factor alpha (TNF-alpha). CP-25, Rituximab and Etanercept reduced the percentage and numbers of CD19⁺ B cells, CD19⁺CD20⁺ B cells, CD19⁺CD27⁺ B cells and CD19⁺CD20⁺CD27⁺ B cells induced by BAFF or TNF-alpha. There was significant difference between CP-25 and Rituximab or CP-25 and Etanercept. CP-25 down-regulated the high expression of BAFFR, BCMA, and TACI stimulated by BAFF or TNF-alpha. The effects of Rituximab and Etanercept on BAFFR or BCMA were stronger than that of CP-25. CP-25, Rituximab and Etanercept down-regulated significantly the expression of TNFR1 and TNFR2 on B cell stimulated by BAFF or TNF-alpha. CP-25, Rituximab and Etanercept down-regulated the expression of MKK3, P-p38, P-p65, TRAF2, and p52 in B cells stimulated by BAFF and the expression of TRAF2 and P-p65 in B cells stimulated by TNF-alpha. These results suggest that CP-25 regulated moderately activated B cells function by regulating the classical and alternative NF-κB signaling pathway mediated by BAFF and TNF-alpha-TRAF2-NF-κB signaling pathway. This study suggests that CP-25 may be a promising anti-inflammatory immune and soft regulation drug.

Methotrexate reduces vaccine-specific immunoglobulin levels but not numbers of circulating antibody-producing B cells in rheumatoid arthritis after vaccination with a conjugate pneumococcal vaccine

BACKGROUND

Treatment with methotrexate (MTX) in patients with rheumatoid arthritis (RA) leads to decreased total immunoglobulin (Ig) levels and impairs vaccine-specific IgG antibody levels following pneumococcal vaccination. The mechanisms by which MTX exerts these effects in RA are unknown. We aimed to evaluate whether MTX reduces vaccine-specific serum Ig levels and their functionality in RA patients following vaccination with pneumococcal conjugate vaccine, and if numbers of antigen-specific circulating plasmablasts are affected.

METHODS

Ten patients with RA on MTX and 10 RA patients without disease modifying anti-rheumatic drug (DMARD) were immunized with a dose 13-valent pneumococcal conjugate vaccine (Prevenar13). Circulating plasmablasts producing total IgG and IgA as well as specific IgG and IgA against two pneumococcal capsular serotypes (6B and 23F) were enumerated using ELISPOT 6days after vaccination. IgG levels against both these serotypes were determined with ELISA before and 4-6weeks after vaccination. Positive antibody response was defined as ⩾2-fold increase of pre-vaccination antibody levels. The functionality of vaccine specific antibodies to serotype 23F was evaluated by measuring their ability to opsonize bacteria using opsonophagocytic assay (OPA) in 4 randomly chosen RA patients on MTX and 4 RA patients without DMARD.

RESULTS

After vaccination, RA patients on MTX showed significant increase in pre- to postvaccination antibody levels for 6B (p<0.05), while patients without DMARD had significant increases for both 6B and 23F (p<0.05 and p<0.01, respectively). Only 10% of RA on MTX and 40% of RA patients without DMARD showed positive post-vaccination antibody responses for both serotypes. Increased opsonizing ability after vaccination was detected in 1 of 4 RA patients on MTX and 3 of 4 patients on RA without DMARD. However, numbers of circulating total and vaccine-specific IgG- or IgA-producing plasmablasts did not differ between RA patients with or without MTX.

CONCLUSIONS

MTX treatment in RA leads to reduced vaccine-specific antibody responses and their functionality compared to untreated RA following pneumococcal vaccination using polysaccharide-protein conjugate vaccine. However, since there was no reduction in numbers of circulating total or vaccine-specific antibody-producing plasmablasts after vaccination this effect is probably not due to reduced activation of B cells in lymphoid tissue.

CLINICAL TRIAL REGISTRATION

NCT02240888.

Immunopathogenesis of granulomas in chronic autoinflammatory diseases

Granulomas are clusters of immune cells. These structures can be formed in reaction to infection and display signs of necrosis, such as in tuberculosis. Alternatively, in several immune disorders, such as sarcoidosis, Crohn's disease and common variable immunodeficiency, non-caseating granulomas are formed without an obvious infectious trigger. Despite advances in our understanding of the human immune system, the pathogenesis underlying these non-caseating granulomas in chronic inflammatory diseases is still poorly understood. Here, we review the current knowledge about the immunopathogenesis of granulomas, and we discuss how the involved immune cells can be targeted with novel therapeutics.

Reduced Number of Transitional and Naive B Cells in Addition to Decreased BAFF Levels in Response to the T Cell Independent Immunogen Pneumovax®23

Protective immunity against T cell independent (TI) antigens such as Streptococcus pneumoniae is characterized by antibody production of B cells induced by the combined activation of T cell independent type 1 and type 2 antigens in the absence of direct T cell help. In mice, the main players in TI immune responses have been well defined as marginal zone (MZ) B cells and B-1 cells. However, the existence of human equivalents to these B cell subsets and the nature of the human B cell compartment involved in the immune reaction remain elusive. We therefore analyzed the effect of a TI antigen on the B cell compartment through immunization of healthy individuals with the pneumococcal polysaccharide (PnPS)-based vaccine Pneumovax^®23, and subsequent characterization of B cell subpopulations. Our data demonstrates a transient decrease of transitional and naïve B cells, with a concomitant increase of IgA⁺ but not IgM⁺ or IgG⁺ memory B cells and a predominant generation of PnPS-specific IgA⁺ producing plasma cells. No alterations could be detected in T cells, or proposed human B-1 and MZ B cell equivalents. Consistent with the idea of a TI immune response, antigen-specific memory responses could not be observed. Finally, BAFF, which is supposed to drive class switching to IgA, was unexpectedly found to be decreased in serum in response to Pneumovax^®23. Our results demonstrate that a characteristic TI response induced by Pneumovax^®23 is associated with distinct phenotypical and functional changes within the B cell compartment. Those modulations occur in the absence of any modulations of T cells and without the development of a specific memory response.

Secondary Antibody Deficiency in Glucocorticoid Therapy Clearly Differs from Primary Antibody Deficiency

PURPOSE

The aim of this study was to identify characteristics of hypogammaglobulinemia secondary to glucocorticoid therapy and their value in the differential diagnosis to primary forms of antibody deficiency.

METHODS

We investigated prevalence and character of hypogammaglobulinemia in a cohort of 36 patients with giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) on glucocorticoid therapy in comparison to a gender- and age-matched cohort of hospital controls. We therefore determined serum immunoglobulin levels as well as B- and T cell-subsets in the peripheral blood of all participants. In addition, prior serum immunoglobulin levels and clinical data of the GCA and PMR patients were extracted from the electronic patient data-base.

RESULTS

21/36 GCA/PMR patients on glucocorticoid treatment developed antibody deficiency. In 19 patients this included IgG and in 13 patients IgG was the only affected isotype. The reduction of IgG was persistent in nearly 50 % of these patients during the observed period. GCA/PMR patients had reduced circulating naive and transitional B cells (p = 0.0043 and p = 0.0002 respectively) while IgM, IgG and IgA memory B cells were preserved. Amongst T-cell subsets, we found a reduction of CD4 memory T cells (p < 0.0001), CD4 regulatory T cells (p = 0.0002) and few CD8 memory T-cell subtypes.

CONCLUSION

Persistent humoral immunodeficiency occurs in about a quarter of GCA/PMR patients under glucocorticoid therapy. Because most patients have isolated IgG deficiency, preserved IgA production and class-switched memory B cells, by these markers this form of secondary hypogammaglobulinemia can be clearly distinguished from common variable immunodeficiency (CVID).

Immunological evaluation of rheumatoid arthritis patients treated with itolizumab

Rheumatoid arthritis is an autoimmune disease characterized by joint inflammation that affects approximately 1% of the general population. Itolizumab, a monoclonal antibody specific for the human CD6 molecule mainly expressed on T lymphocytes, has been shown to inhibit proliferation of T cells and proinflammatory cytokine production in psoriasis patients. We have now assessed the immunological effect of itolizumab in combination with methotrexate in rheumatoid arthritis by analyzing clinical samples taken from 30 patients enrolled in a clinical trial. T and B cell subpopulations were measured at different time points of the study. Plasma cytokine levels and anti-idiotypic antibody response to itolizumab were also evaluated. The combined treatment of itolizumab and methotrexate led to a reduction in the frequency of T cell subpopulations, and plasma levels of proinflammatory cytokines showed a significant decrease up to at least 12 weeks after treatment ended. No anti-idiotypic antibody response was detected. These results support the relevance of the CD6 molecule as a therapeutic target for the treatment of this disease.