Exploratory mass cytometry analysis reveals immunophenotypes of cancer treatment-related pneumonitis

Anticancer treatments can result in various adverse effects, including infections due to immune suppression/dysregulation and drug-induced toxicity in the lung. One of the major opportunistic infections is Pneumocystis jirovecii pneumonia (PCP), which can cause severe respiratory complications and high mortality rates. Cytotoxic drugs and immune-checkpoint inhibitors (ICIs) can induce interstitial lung diseases (ILDs). Nonetheless, the differentiation of these diseases can be difficult, and the pathogenic mechanisms of such diseases are not yet fully understood. To better comprehend the immunophenotypes, we conducted an exploratory mass cytometry analysis of immune cell subsets in bronchoalveolar lavage fluid from patients with PCP, cytotoxic drug-induced ILD (DI-ILD), and ICI-associated ILD (ICI-ILD) using two panels containing 64 markers. In PCP, we observed an expansion of the CD16+ T cell population, with the highest CD16+ T proportion in a fatal case. In ICI-ILD, we found an increase in CD57+ CD8+ T cells expressing immune checkpoints (TIGIT+ LAG3+ TIM-3+ PD-1+), FCRL5+ B cells, and CCR2+ CCR5+ CD14+ monocytes. These findings uncover the diverse immunophenotypes and possible pathomechanisms of cancer treatment-related pneumonitis.

Role of signaling lymphocytic activation molecule family of receptors in the pathogenesis of rheumatoid arthritis: insights and application

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and joint damage. The signaling lymphocytic activation molecule (SLAMF) family of receptors are expressed on various hematopoietic and non-hematopoietic cells and can regulate both immune cell activation and cytokine production. Altered expression of certain SLAMF receptors contributes to aberrant immune responses in RA. In RA, SLAMF1 is upregulated on T cells and may promote inflammation by participating in immune cell-mediated responses. SLAMF2 and SLAMF4 are involved in regulating monocyte tumor necrosis factor production and promoting inflammation. SLAMF7 activates multiple inflammatory pathways in macrophages to drive inflammatory gene expression. SLAMF8 inhibition can reduce inflammation in RA by blocking ERK/MMPs signaling. Of note, there are differences in SLAMF receptor (SFR) expression between normal and arthritic joint tissues, suggesting a role as potential diagnostic biomarkers. This review summarizes recent advances on the roles of SLAMF receptors 1, 2, 4, 7, and 8 in RA pathogenesis. However, further research is needed to elucidate the mechanisms of SLAMF regulation of immune cells in RA. Understanding interactions between SLAMF receptors and immune cells will help identify selective strategies for targeting SLAMF signaling without compromising normal immunity. Overall, the SLAMF gene family holds promise as a target for precision medicine in RA, but additional investigation of the underlying immunological mechanisms is needed. Targeting SLAMF receptors presents opportunities for new diagnostic and therapeutic approaches to dampen damaging immune-mediated inflammation in RA.

Treatment of autoimmunity: The impact of disease-modifying therapies in multiple sclerosis and comorbid autoimmune disorders

More than 10 disease-modifying therapies (DMT) are approved by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) for the treatment of multiple sclerosis (MS) and new therapeutic options are on the horizon. Due to different underlying therapeutic mechanisms, a more individualized selection of DMTs in MS is possible, taking into account the patient's current situation. Therefore, concomitant treatment of various comorbid conditions, including autoimmune mediated disorders such as rheumatoid arthritis, should be considered in MS patients. Because the pathomechanisms of autoimmunity partially overlap, DMT could also treat concomitant inflammatory diseases and simplify the patient's treatment. In contrast, the exacerbation and even new occurrence of several autoimmune diseases have been reported as a result of immunomodulatory treatment of MS. To simplify treatment and avoid disease exacerbation, knowledge of the beneficial and adverse effects of DMT in other autoimmune disorders is critical. Therefore, we conducted a literature search and described the beneficial and adverse effects of approved and currently studied DMT in a large number of comorbid autoimmune diseases, including rheumatoid arthritis, ankylosing spondylitis, inflammatory bowel diseases, cutaneous disorders including psoriasis, Sjögren´s syndrome, systemic lupus erythematosus, systemic vasculitis, autoimmune hepatitis, and ocular autoimmune disorders. Our review aims to facilitate the selection of an appropriate DMT in patients with MS and comorbid autoimmune diseases.

Mass cytometry identifies characteristic immune cell subsets in bronchoalveolar lavage fluid from interstitial lung diseases

Immune cells have been implicated in interstitial lung diseases (ILDs), although their phenotypes and effector mechanisms remain poorly understood. To better understand these cells, we conducted an exploratory mass cytometry analysis of immune cell subsets in bronchoalveolar lavage fluid (BALF) from patients with idiopathic pulmonary fibrosis (IPF), connective-tissue disease (CTD)-related ILD, and sarcoidosis, using two panels including 64 markers. Among myeloid cells, we observed the expansion of CD14⁺ CD36^hi CD84^hiCCR2^- monocyte populations in IPF. These CD14⁺ CD36^hi CD84^hi CCR2^- subsets were also increased in ILDs with a progressive phenotype, particularly in a case of acute exacerbation (AEx) of IPF. Analysis of B cells revealed the presence of cells at various stages of differentiation in BALF, with a higher percentage of IgG memory B cells in CTD-ILDs and a trend toward more FCRL5⁺ B cells. These FCRL5⁺ B cells were also present in the patient with AEx-IPF and sarcoidosis with advanced lung lesions. Among T cells, we found increased levels of IL-2R⁺ TIGIT⁺ LAG3⁺ CD4⁺ T cells in IPF, increased levels of CXCR3⁺ CD226⁺ CD4⁺ T cells in sarcoidosis, and increased levels of PD1⁺ TIGIT⁺ CD57⁺ CD8⁺ T cells in CTD-ILDs. Together, these findings underscore the diverse immunopathogenesis of ILDs.

Ocrelizumab in Patients with Active Primary Progressive Multiple Sclerosis: Clinical Outcomes and Immune Markers of Treatment Response

Ocrelizumab is a B-cell-depleting monoclonal antibody approved for the treatment of relapsing-remitting multiple sclerosis (RRMS) and active primary progressive MS (aPPMS). This prospective, uncontrolled, open-label, observational study aimed to assess the efficacy of ocrelizumab in patients with aPPMS and to dissect the clinical, radiological and laboratory attributes of treatment response. In total, 22 patients with aPPMS followed for 24 months were included. The primary efficacy outcome was the proportion of patients with optimal response at 24 months, defined as patients free of relapses, free of confirmed disability accumulation (CDA) and free of T1 Gd-enhancing lesions and new/enlarging T2 lesions on the brain and cervical MRI. In total, 14 (63.6%) patients and 13 patients (59.1%) were classified as responders at 12 and 24 months, respectively. Time exhibited a significant effect on mean absolute and normalized gray matter cerebellar volume (F = 4.342, p = 0.23 and F = 4.279, p = 0.024, respectively). Responders at 24 months exhibited reduced peripheral blood ((%) of CD19+ cells) plasmablasts compared to non-responders at the 6-month point estimate (7.69 ± 4.4 vs. 22.66 ± 7.19, respectively, p = 0.043). Response to ocrelizumab was linked to lower total and gray matter cerebellar volume loss over time. Reduced plasmablast depletion was linked for the first time to sub-optimal response to ocrelizumab in aPPMS.

Ulcerative colitis is characterized by a plasmablast-skewed humoral response associated with disease activity

B cells, which are critical for intestinal homeostasis, remain understudied in ulcerative colitis (UC). In this study, we recruited three cohorts of patients with UC (primary cohort, n = 145; validation cohort 1, n = 664; and validation cohort 2, n = 143) to comprehensively define the landscape of B cells during UC-associated intestinal inflammation. Using single-cell RNA sequencing, single-cell IgH gene sequencing and protein-level validation, we mapped the compositional, transcriptional and clonotypic landscape of mucosal and circulating B cells. We found major perturbations within the mucosal B cell compartment, including an expansion of naive B cells and IgG⁺ plasma cells with curtailed diversity and maturation. Furthermore, we isolated an auto-reactive plasma cell clone targeting integrin αvβ6 from inflamed UC intestines. We also identified a subset of intestinal CXCL13-expressing TFH-like T peripheral helper cells that were associated with the pathogenic B cell response. Finally, across all three cohorts, we confirmed that changes in intestinal humoral immunity are reflected in circulation by the expansion of gut-homing plasmablasts that correlates with disease activity and predicts disease complications. Our data demonstrate a highly dysregulated B cell response in UC and highlight a potential role of B cells in disease pathogenesis.

Discovery of a novel Igβ and FcγRIIB cross-linking antibody, ASP2713, and its potential application in the treatment of systemic lupus erythematosus

B cell-targeted therapies have evolved as established therapies for systemic lupus erythematosus (SLE); however, existing approaches still do not thoroughly satisfy clinical requirements due to limited efficacy against memory B cells, autoantibody-producing plasmablasts and disease heterogeneity. To provide a new treatment option for SLE, we created a novel anti-Igβ antibody with enhanced affinity for Fc gamma receptor (FcγR) IIB called ASP2713. ASP2713 cross-reacted with both human and cynomolgus monkey Igβ and showed increased binding affinity for human and monkey FcγRIIB compared to native human IgG1. This binding property allows dominant B cell binding and induction of intrinsic negative feedback signals. In human B cells, ASP2713 significantly and concentration-dependently induced FcγRIIB ITIM phosphorylation, while suppressing proliferation under B cell receptor stimulation. This pharmacological effect was also confirmed in in vitro B cell proliferation and antibody production assays using peripheral B cells isolated from patients with SLE. In a cynomolgus monkey tetanus toxoid-induced antibody production model, ASP2713 almost completely inhibited the increase in antigen-specific antibodies with superior efficacy to rituximab. Additionally, ASP2713 significantly suppressed recall antibody production in response to secondary tetanus toxoid immunization, indicating the memory B cell- and plasmablast-targeting potential of ASP2713. Our results suggest that ASP2713 may have therapeutic potential as a treatment for SLE, where B cells play a pathogenic role.

Increasing numbers of CD19 + CD24highCD38high regulatory B cells and pre-germinal center B cells reflect activated autoimmunity and predict future treatment response in patients with untreated immune thrombocytopenia

The pathophysiology of immune thrombocytopenia (ITP) is poorly understood, particularly aspects regarding abnormal homeostasis and dysregulation of B cells. In this study, we analyzed peripheral lymphocyte subsets in patients with untreated ITP and healthy controls, and examined correlations between cell percentages/counts and titers of serum cytokines and antibodies. We also compared ITP patients who later required second-line therapies and those who did not. The percentages of CD19 + CD24^highCD38^high regulatory B cells, pre-germinal center (GC) B cells, and plasmablast-like B cells were significantly higher in ITP patients than in healthy controls. Absolute counts of regulatory B cells and pre-GC B cells were significantly higher in those who needed second-line therapies. In addition, serum B cell-activating factor belonging to the tumor necrosis factor family (BAFF) levels and platelet-associated immune globulin G antibody titers correlated positively with regulatory B cell, pre-GC B cell, and auto-reactive B cell counts. Serum interferon-α (IFN-α) levels were elevated in four ITP patients with high auto-reactive B cell counts. These results indicate that increases in regulatory B cells and pre-GC B cells may reflect activated autoimmunity induced by BAFF and/or IFN-α. Consequently, evaluation of B cell subsets in untreated ITP patients may predict treatment response.

The growing role of precision medicine for the treatment of autoimmune diseases; results of a systematic review of literature and Experts' Consensus

Autoimmune diseases (AIDs) share similar serological, clinical, and radiological findings, but, behind these common features, there are different pathogenic mechanisms, immune cells dysfunctions, and targeted organs. In this context, multiple lines of evidence suggest the application of precision medicine principles to AIDs to reduce the treatment failure. Precision medicine refers to the tailoring of therapeutic strategies to the individual characteristics of each patient, thus it could be a new approach for management of AIDS which considers individual variability in genes, environmental exposure, and lifestyle. Precision medicine would also assist physicians in choosing the right treatment, the best timing of administration, consequently trying to maximize drug efficacy, and, possibly, reducing adverse events. In this work, the growing body of evidence is summarized regarding the predictive factors for drug response in patients with AIDs, applying the precision medicine principles to provide high-quality evidence for therapeutic opportunities in improving the management of these patients.

Definition of erythroid cell-positive blood transcriptome phenotypes associated with severe respiratory syncytial virus infection

Biomarkers to assess the risk of developing severe respiratory syncytial virus (RSV) infection are needed. We conducted a meta-analysis of 490 unique profiles from six public RSV blood transcriptome datasets. A repertoire of 382 well-characterized transcriptional modules was used to define dominant host responses to RSV infection. The consolidated RSV cohort was stratified according to four traits: "interferon response" (IFN), "neutrophil-driven inflammation" (Infl), "cell cycle" (CC), and "erythrocytes" (Ery). We identified eight prevalent blood transcriptome phenotypes, of which three Ery+ phenotypes comprised higher proportions of patients requiring intensive care. This finding confirms on a larger scale data from one of our earlier reports describing an association between an erythrocyte signature and RSV disease severity. Further contextual interpretation made it possible to associate this signature with immunosuppressive states (late stage cancer, pharmacological immunosuppression), and with a population of fetal glycophorin A+ erythroid precursors. Furthermore, we posit that this erythrocyte cell signature may be linked to a population of immunosuppressive erythroid cells previously described in the literature, and that overabundance of this cell population in RSV patients may underlie progression to severe disease. These findings outline potential priority areas for biomarker development and investigations into the immune biology of RSV infection. The approach that we developed and employed here should also permit to delineate prevalent blood transcriptome phenotypes in other settings.

Fc receptor-like 5 and anti-CD20 treatment response in granulomatosis with polyangiitis and microscopic polyangiitis

BACKGROUND

Baseline expression of FCRL5, a marker of naive and memory B cells, was shown to predict response to rituximab (RTX) in rheumatoid arthritis. This study investigated baseline expression of FCRL5 as a potential biomarker of clinical response to RTX in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).

METHODS

A previously validated quantitative PCR–based (qPCR-based) platform was used to assess FCRL5 expression in patients with GPA/MPA (RAVE trial, NCT00104299).

RESULTS

Baseline FCRL5 expression was significantly higher in patients achieving complete remission (CR) at 6, 12, and 18 months, independent of other clinical and serological variables, among those randomized to RTX but not cyclophosphamide-azathioprine (CYC/AZA). Patients with baseline FCRL5 expression ≥ 0.01 expression units (termed FCRL5^hi) exhibited significantly higher CR rates at 6, 12, and 18 months as compared with FCRL5^lo subjects (84% versus 57% [P = 0.016], 68% versus 40% [P = 0.02], and 68% versus 29% [P = 0.0009], respectively).

CONCLUSION

Our data taken together suggest that FCRL5 is a biomarker of B cell lineage associated with increased achievement and maintenance of complete remission among patients treated with RTX and warrant further investigation in a prospective manner.

FUNDING

The analysis for this study was funded by Genentech Inc.

FcRL5 is a biomarker of B cell lineage associated with maintenance of complete remission among patients treated with rituximab in granulomatosis with polyangiitis and microscopic polyangiitis.

Effect of rituximab treatment on T and B cell subsets in lymph node biopsies of patients with rheumatoid arthritis

Objectives

The exact underlying mechanism of rituximab treatment in patients with RA is poorly defined and knowledge about the effect of B cell depletion on immune cells in secondary lymphoid organs is lacking. We analysed lymphoid tissue responses to rituximab in RA patients.

Methods

Fourteen RA patients received 2 × 1000 mg rituximab intravenously, and lymph node (LN) biopsies were obtained before and 4 weeks after the first infusion. Tissues were examined by flow cytometry, immunohistochemistry and quantitative PCR. LN biopsies from five healthy individuals (HC) served as controls.

Results

LN biopsies of RA patients showed increased frequencies of CD21⁺CD23⁺IgD^highIgM^variable follicular B cells and CD3⁺CD25⁺CD69⁺ early activated, tissue resident T cells when compared with HCs. After treatment, there was incomplete depletion of LN B cells. There was a significant decrease in CD27⁻IgD⁺ naïve B cells, and CD27⁺IgD⁺ unswitched memory B cells including the CD27⁺IgD⁺IgM⁺ subset and follicular B cells. Strikingly, CD27⁺IgD⁻ switched memory B cells persisted in LN biopsies after rituximab treatment. In the T cell compartment, a significant decrease was observed in the frequency of early activated, tissue resident T cells after rituximab treatment, but late activated T cells persisted. B cell proliferation inducing cytokine IL-21 was higher expressed in LN biopsies of RA patients compared with HC and expression was not affected by rituximab treatment.

Conclusion

Rituximab does not cure RA, possibly due to persistence of switched memory B cells in lymphoid tissues suggesting that factors promoting B cell survival and differentiation need to be additionally targeted.

Genetic risk of FCRL3 and FCRL5 polymorphisms in children with asthma and allergic rhinitis in a Chinese Han population

OBJECTIVES

Asthma and allergic rhinitis (AR) frequently occur as comorbid diseases of the upper airways. Single-nucleotide polymorphisms (SNPs) in the FCRL3 and FCRL5 genes have recently been shown to be associated with various immune-related disorders. This study evaluated the association of FCRL3 and FCRL5 polymorphisms with asthma and allergic rhinitis (AR) in a Han Chinese population.

METHODS

Seven single nucleotide polymorphisms (SNPs) of the FCRL3 and FCRL5 were genotyped in 300 asthmatic children, and 206 healthy unrelated individuals using PCR-restriction fragment length polymorphism (PCR-RFLP) assay. Genotyping was validated by direct sequencing.

RESULTS

Our results showed that the frequencies of the rs6692977 CT genotype and T allele within FCRL5 were significantly higher in asthma with comorbid AR compared to healthy controls (Bonferroni-corrected p (Pc) = 3.75 × 10^-6; Pc = 0.006, respectively), whereas these of the CC genotype and C allele were significantly lower (Pc = 4.15 × 10^-5; Pc = 0.006, respectively). The frequencies of the rs7528684 A allele (Pc = 1.80 × 10^-3) and the rs10489678 G allele (Pc = 0.04) within FCRL3 were higher in asthma with comorbid AR than in controls. However, no differences in the tested genetic polymorphisms were detected between asthma and healthy individuals.

CONCLUSION

This study identified novel SNPs in FCRL3 and FCRL5 significantly associated with the risk for asthma with comorbid AR in the Chinese population. The genetic variants may play role in the development of the asthma phenotype in children with asthma.

Baseline Plasma Cell Gene Signature Predicts Improvement in Systemic Sclerosis Skin Scores Following Treatment With Inebilizumab (MEDI-551) and Correlates With Disease Activity in Systemic Lupus Erythematosus and Chronic Obstructive Pulmonary Disease

OBJECTIVE

B cells impact the progression of systemic sclerosis (SSc; scleroderma) through multiple pathogenic mechanisms. CD19 inhibition in mice reduced skin thickness, collagen production, and autoantibody levels, consistent with CD19 expression on plasma cells (PCs), the source of antibody production. PC depletion could effectively reduce collagen deposition and inflammation in SSc; therefore, we investigated the effects of PC depletion on SSc disease activity.

METHODS

A PC gene signature was evaluated in SSc skin biopsy samples in 2 phase I clinical trials. We assessed microarray data from tissue from public studies of chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), dermatomyositis (DM), systemic lupus erythematosus (SLE), and atopic dermatitis, as well as blood from a phase IIb clinical trial in SLE.

RESULTS

The PC signature was elevated in SSc skin specimens compared to healthy donor skin (P = 2.28 × 10^-6 ) and correlated with the baseline modified Rodnan skin thickness score (MRSS) (r = 0.64, P = 0.0004). Patients with a high PC signature at baseline showed greater improvement in the MRSS (mean ± SD change 35 ± 16%; P = 6.30 × 10^-4 ) following anti-CD19 treatment with inebilizumab (MEDI-551) than did patients with a low PC signature at baseline (mean ± SD change 8 ± 12%; P = 0.104). The PC signature was overexpressed in tissue from patients with SLE, DM, COPD, interstitial lung disease, and IPF relative to controls (all fold change >2; P < 0.001). The PC signature also differed significantly between SLE patients with mild-to-moderate disease and those with severe disease (SLE Disease Activity Index cutoff at 10) (fold change 1.44; P = 3.90 × 10^-3 ) and correlated significantly with the degree of emphysema in COPD (r = 0.53, P = 7.55 × 10^-8 ).

CONCLUSION

Our results support the notion that PCs have a role in the pathogenesis of SSc and other autoimmune or pulmonary indications. An elevated pretreatment PC signature was associated with increased benefit from MEDI-551 in SSc.

Genotypes, phenotypes and treatment with immunomodulators in the rheumatic diseases

The autoimmune rheumatological diseases rheumatoid arthritis (RA), spondyloarthritis (SpA) and systemic lupus erythematosus (SLE) are treated with conventional immunosuppressive agents and with modern biological immunomodulators. The latter group of medications have brought about a major change in our ability to control RA and SpA, with more modest results for SLE. The biologicals are very specific in their mechanisms of action, targeting one specific cytokine or one particular cellular marker. Because of this, their efficacy can readily be linked to a single immunomodulatory mechanism. This observation has fuelled hopes that the efficacy of these agents can be predicted at the individual level based on the patient's genetic predisposition, immunological profile or disease phenotype. Whilst the biologic therapies have improved the prospects for patients with these diseases very significantly, the hope that they could be targeted to the patient in an individualized manner has not completely born fruit. In this review, I will argue that we are witnessing important progress in this field, and that justified hope exists for true advances in precision medicine in the autoimmune diseases in the coming years.

Pharmacokinetics and pharmacodynamics of the cytolytic anti-CD38 human monoclonal antibody TAK-079 in monkey - model assisted preparation for the first in human trial

We are studying the fully human, IgG1λ cytolytic monoclonal antibody TAK-079, which binds CD38. CD38 is expressed on plasma and natural killer (NK) cells constitutively and upregulated on subsets of B and T lymphocytes upon activation. TAK-079 cross-reacts with CD38 expressed by cynomolgus monkeys and depletes subsets of NK, B, and T cells. Therefore, safety and function of TAK-079 was evaluated in this species, prior to clinical development, using bioanalytical, and flow cytometry assays. We pooled the data from eight studies in healthy monkeys (dose range 0.03-100 mg/kg) and developed mathematical models that describe the pharmacokinetics and the exposure-effect relationship for NK cells, B cells, and T cells. NK cell depletion was identified as the most sensitive pharmacodynamic effect of TAK-079. It was adequately described with a turnover model (C₅₀  = 27.5 μg/mL on depletion rate) and complete depletion was achieved with an IV dose of 0.3 mg/kg. Intermediate effects on T-cell counts were described with a direct response model (C₅₀  = 11.9 μg/mL) and on B-cell counts with a 4-transit-compartment model (C₅₀  = 19.8 μg/mL on depletion rate). Our analyses substantiate the observation that NK, B and T cells are cleared by TAK-079 at different rates and required different time spans to replete the blood compartment. The models were used to simulate pharmacokinetic and cell depletion profiles in humans after applying a straightforward scaling approach for monoclonal antibodies in preparation for the first-in-human clinical trial.

The SLAM family receptors: Potential therapeutic targets for inflammatory and autoimmune diseases

The signaling lymphocytic activation molecule (SLAM) family is comprised of nine distinct receptors (SLAMF1 through SLAMF9) that are expressed on hematopoietic cells. All of these receptors, with the exception of SLAMF4, are homotypic by nature as downstream signaling occurs when hematopoietic cells that express the same SLAM receptor interact. The SLAM family receptor function is largely controlled via SLAM associated protein (SAP) family adaptors. The SAP family adaptors consist of SAP, Ewing sarcoma associated transcript (EAT)-2, and EAT-2-related transducer (ERT). These adaptors associate with the cytoplasmic domain of the SLAM family receptors through phosphorylated tyrosines. Defects in SLAM family members and SAP adaptors have been implicated in causing immune deficiencies. This is exemplified in patients with X-linked lymphoproliferative (XLP) disease, where SAP undergoes a loss of function mutation. Furthermore, evidence has been accumulating that SLAM family members are potential targets for inflammatory and autoimmune diseases. This review will discuss the structure and function of the SLAM family receptors and SAP family adaptors, their role in immune regulation, and potential approaches to target this family of receptors therapeutically.

Integrative analysis reveals CD38 as a therapeutic target for plasma cell-rich pre-disease and established rheumatoid arthritis and systemic lupus erythematosus

Background

Plasmablasts and plasma cells play a key role in many autoimmune diseases, such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). This study was undertaken to evaluate the potential of targeting CD38 as a plasma cell/plasmablast depletion mechanism by daratumumab in the treatment of patients with RA and SLE.

Methods

RNA-sequencing analysis of synovial biopsies from various stages of RA disease progression, flow cytometry analysis of peripheral blood mononuclear cells (PBMC) from patients with RA or SLE and healthy donors, immunohistochemistry assessment (IHC) of synovial biopsies from patients with early RA, and ex vivo immune cell depletion assays using daratumumab (an anti-CD38 monoclonal antibody) were used to assess CD38 as a therapeutic target.

Results

We demonstrated that the plasma cell/plasmablast-related genes CD38, XBP1, IRF4, PRDM1, IGJ and TNFSF13B are significantly up-regulated in synovial biopsies from patients with arthralgia, undifferentiated arthritis (UA), early RA and established RA as compared to healthy controls and control patients with osteoarthritis. In addition, the highest CD38 expression was observed on plasma cells and plasmablasts compared to natural killer (NK) cells, classical dendritic cells (DCs), plasmacytoid DCs (pDCs) and T cells, in blood from healthy controls and patients with SLE and RA. Furthermore, IHC showed CD38 staining in the same region as CD3 and CD138 staining in synovial tissue biopsies from patients with early RA. Most importantly, our data show for the first time that daratumumab effectively depletes plasma cells/plasmablasts in PBMC from patients with SLE and RA in a dose-dependent manner ex vivo.

Conclusion

These results indicate that CD38 may be a potential target for RA disease interception and daratumumab should be evaluated clinically for the treatment of both RA and SLE.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1578-z) contains supplementary material, which is available to authorized users.

Antibody repertoire analysis in polygenic autoimmune diseases

High-throughput sequencing of the DNA/RNA encoding antibody heavy- and light-chains is rapidly transforming the field of adaptive immunity. It can address key questions, including: (i) how the B-cell repertoire differs in health and disease; and (ii) if it does differ, the point(s) in B-cell development at which this occurs. The advent of technologies, such as whole-genome sequencing, offers the chance to link abnormalities in the B-cell antibody repertoire to specific genomic variants and polymorphisms. Here, we discuss the current research using B-cell antibody repertoire sequencing in three polygenic autoimmune diseases where there is good evidence for a pathological role for B-cells, namely systemic lupus erythematosus, multiple sclerosis and rheumatoid arthritis. These autoimmune diseases exhibit significantly skewed B-cell receptor repertoires compared with healthy controls. Interestingly, some common repertoire defects are shared between diseases, such as elevated IGHV4-34 gene usage. B-cell clones have effectively been characterized and tracked between different tissues and blood in autoimmune disease. It has been hypothesized that these differences may signify differences in B-cell tolerance; however, the mechanisms and implications of these defects are not clear.

NF-κB inducing kinase is a therapeutic target for systemic lupus erythematosus

NF-κB-inducing kinase (NIK) mediates non-canonical NF-κB signaling downstream of multiple TNF family members, including BAFF, TWEAK, CD40, and OX40, which are implicated in the pathogenesis of systemic lupus erythematosus (SLE). Here, we show that experimental lupus in NZB/W F1 mice can be treated with a highly selective and potent NIK small molecule inhibitor. Both in vitro as well as in vivo, NIK inhibition recapitulates the pharmacological effects of BAFF blockade, which is clinically efficacious in SLE. Furthermore, NIK inhibition also affects T cell parameters in the spleen and proinflammatory gene expression in the kidney, which may be attributable to inhibition of OX40 and TWEAK signaling, respectively. As a consequence, NIK inhibition results in improved survival, reduced renal pathology, and lower proteinuria scores. Collectively, our data suggest that NIK inhibition is a potential therapeutic approach for SLE.

High-throughput characterization of the functional impact of IgG Fc glycan aberrancy in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) encompasses all forms of chronic idiopathic arthritis that arise before age 16. Previous studies have found JIA to be associated with lower Fc galactosylation of circulating IgG, but the overall spectrum of glycan changes and the net impact on IgG function are unknown. Using ultra performance liquid chromatography (UPLC), we compared IgG glycosylation in 54 subjects with recent-onset untreated JIA with 98 healthy pediatric controls, paired to biophysical profiling of affinity for 20 IgG receptors using a high-throughput multiplexed microsphere assay. Patients with JIA exhibited an increase in hypogalactosylated and hyposialylated IgG glycans, but no change in fucosylation or bisection, together with alteration in the spectrum of IgG ligand binding. Supervised machine learning demonstrated a robust capacity to discriminate JIA subjects from controls using either glycosylation or binding data. The binding signature was driven predominantly by enhanced affinity for Fc receptor like protein 5 (FcRL5), a noncanonical Fc receptor expressed on B cells. Affinity for FcRL5 correlated inversely with galactosylation and sialylation, a relationship confirmed through enzymatic manipulation. These results demonstrate the capacity of combined structural and biophysical IgG phenotyping to define the overall functional impact of IgG glycan changes and implicate FcRL5 as a potential cellular sensor of IgG glycosylation.

Right drug, right patient, right time: aspiration or future promise for biologics in rheumatoid arthritis?

Individualising biologic disease-modifying anti-rheumatic drugs (bDMARDs) to maximise outcomes and deliver safe and cost-effective care is a key goal in the management of rheumatoid arthritis (RA). Investigation to identify predictive tools of bDMARD response is a highly active and prolific area of research. In addition to clinical phenotyping, cellular and molecular characterisation of synovial tissue and blood in patients with RA, using different technologies, can facilitate predictive testing. This narrative review will summarise the literature for the available bDMARD classes and focus on where progress has been made. We will also look ahead and consider the increasing use of ‘omics’ technologies, the potential they hold as well as the challenges, and what is needed in the future to fully realise our ambition of personalised bDMARD treatment.

A blinded, randomized clinical trial evaluating the efficacy and safety of lokivetmab compared to ciclosporin in client-owned dogs with atopic dermatitis

BACKGROUND

Lokivetmab is an injectable anti-canine-IL-31 monoclonal antibody to treat clinical manifestations of atopic dermatitis (AD) in dogs.

HYPOTHESIS/OBJECTIVES

To characterize the efficacy and safety of lokivetmab, and to demonstrate its noninferiority to ciclosporin under field conditions.

ANIMALS

Dogs with chronic AD (n = 274) were enrolled from 40 practices in Belgium, The Netherlands, France and Germany.

METHODS

Animals were randomized (1:1) to oral ciclosporin (5 mg/kg/once daily) or monthly injectable lokivetmab (1-3.3 mg/kg) for three months. Eighty one animals that successfully completed the comparative phase were enrolled in a continuation phase receiving lokivetmab for an additional six months. Owners assessed pruritus on a Visual Analog Scale, skin lesions were assessed by veterinary investigators with a Canine AD Extent and Severity Index (CADESI-03) scale.

RESULTS

Lokivetmab was noninferior to ciclosporin for pruritus reduction on Day 28 (51.90% versus 43.72%). For Day 28 CADESI-03 percentage reduction, noninferiority of lokivetmab (54.17) versus ciclosporin (56.86%) was not achieved. At none of the time points were mean CADESI-03 scores significantly different between groups. Continued efficacy towards pruritus and lesions was demonstrated in the continuation phase where 76.3% of animals (n = 45) were assessed as 'normal' for pruritus at study end. No abnormal health events associated with lokivetmab were observed during the initial three month phase (142 dogs) or during the subsequent six month phase (81 dogs).

CONCLUSIONS AND CLINICAL IMPORTANCE

Lokivetmab at a minimum monthly dose of 1 mg/kg provided quick onset (within one day) of a lasting effect in reducing pruritus and skin lesions with a good safety profile.

Autoantibody-producing plasmablasts after B cell depletion identified in muscle-specific kinase myasthenia gravis

Myasthenia gravis (MG) is a B cell-mediated autoimmune disorder of neuromuscular transmission. Pathogenic autoantibodies to muscle-specific tyrosine kinase (MuSK) can be found in patients with MG who do not have detectable antibodies to the acetylcholine receptor (AChR). MuSK MG includes immunological and clinical features that are generally distinct from AChR MG, particularly regarding responsiveness to therapy. B cell depletion has been shown to affect a decline in serum autoantibodies and to induce sustained clinical improvement in the majority of MuSK MG patients. However, the duration of this benefit may be limited, as we observed disease relapse in MuSK MG patients who had achieved rituximab-induced remission. We investigated the mechanisms of such relapses by exploring autoantibody production in the reemerging B cell compartment. Autoantibody-expressing CD27+ B cells were observed within the reconstituted repertoire during relapse but not during remission or in controls. Using two complementary approaches, which included production of 108 unique human monoclonal recombinant immunoglobulins, we demonstrated that antibody-secreting CD27hiCD38hi B cells (plasmablasts) contribute to the production of MuSK autoantibodies during relapse. The autoantibodies displayed hallmarks of antigen-driven affinity maturation. These collective findings introduce potential mechanisms for understanding both MuSK autoantibody production and disease relapse following B cell depletion.

Understanding Human Autoimmunity and Autoinflammation Through Transcriptomics

Transcriptomics, the high-throughput characterization of RNAs, has been instrumental in defining pathogenic signatures in human autoimmunity and autoinflammation. It enabled the identification of new therapeutic targets in IFN-, IL-1- and IL-17-mediated diseases. Applied to immunomonitoring, transcriptomics is starting to unravel diagnostic and prognostic signatures that stratify patients, track molecular changes associated with disease activity, define personalized treatment strategies, and generally inform clinical practice. Herein, we review the use of transcriptomics to define mechanistic, diagnostic, and predictive signatures in human autoimmunity and autoinflammation. We discuss some of the analytical approaches applied to extract biological knowledge from high-dimensional data sets. Finally, we touch upon emerging applications of transcriptomics to study eQTLs, B and T cell repertoire diversity, and isoform usage.

Biomarkers to guide clinical therapeutics in rheumatology?

PURPOSE OF REVIEW

The use of biomarkers in rheumatology can help identify disease risk, improve diagnosis and prognosis, target therapy, assess response to treatment, and further our understanding of the underlying pathogenesis of disease. Here, we discuss the recent advances in biomarkers for rheumatic disorders, existing impediments to progress in this field, and the potential of biomarkers to enable precision medicine and thereby transform rheumatology.

RECENT FINDINGS

Although significant challenges remain, progress continues to be made in biomarker discovery and development for rheumatic diseases. The use of next-generation technologies, including large-scale sequencing, proteomic technologies, metabolomic technologies, mass cytometry, and other single-cell analysis and multianalyte analysis technologies, has yielded a slew of new candidate biomarkers. Nevertheless, these biomarkers still require rigorous validation and have yet to make their way into clinical practice and therapeutic development. This review focuses on advances in the biomarker field in the last 12 months as well as the challenges that remain.

SUMMARY

Better biomarkers, ideally mechanistic ones, are needed to guide clinical decision making in rheumatology. Although the use of next-generation techniques for biomarker discovery is making headway, it is imperative that the roadblocks in our search for new biomarkers are overcome to enable identification of biomarkers with greater diagnostic and predictive utility. Identification of biomarkers with robust diagnostic and predictive utility would enable precision medicine in rheumatology.

Targeting B cells in relapsing-remitting multiple sclerosis: from pathophysiology to optimal clinical management

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease that is caused by an autoimmune response against central nervous system (CNS) structures. Traditionally considered a T-cell-mediated disorder, the contribution of B cells to the pathogenesis of MS has long been debated. Based on recent promising clinical results from CD20-depleting strategies by three therapeutic monoclonal antibodies in clinical phase II and III trials (rituximab, ocrelizumab and ofatumumab), targeting B cells in MS is currently attracting growing interest among basic researchers and clinicians. Many questions about the role of B and plasma cells in MS remain still unanswered, ranging from the role of specific B-cell subsets and functions to the optimal treatment regimen of B-cell depletion and monitoring thereafter. Here, we will assess our current knowledge of the mechanisms implicating B cells in multiple steps of disease pathology and examine current and future therapeutic approaches for the treatment of MS.

A combination of cellular biomarkers predicts failure to respond to rituximab in rheumatoid arthritis: a 24-week observational study

BACKGROUND

Although B cell depletion with rituximab (RTX) is an effective treatment strategy in rheumatoid arthritis (RA), one third of patients do not achieve remission or low disease activity (LDA). Thus, identifying patients who will benefit from RTX is highly desirable. In the present study we investigated whether lymphocyte subsets other than B cells are predictors of a clinical response to RTX treatment.

METHODS

Patients with RA who were receiving RTX for the first time were included in an observatory registry. Clinical assessments, complete blood count and flow cytometry of lymphocyte subsets were obtained at baseline and at week 24 after RTX. Complete data were available for 44 patients. Logistic regression and receiver operating characteristic curve analyses were computed to analyze the predictive value of lymphocyte subsets for European League Against Rheumatism (EULAR) response and LDA (defined as disease activity score in 28 joints (DAS28) ≤3.2) at week 24.

RESULTS

EULAR responders had lower total lymphocyte counts (LC), T cells and CD4 + T cells at baseline. Although these parameters were independent predictors of EULAR response they failed in determining who would reach LDA. In contrast, LC >2910/μl or plasmablast frequency >2.85 % at baseline predicted a significantly higher DAS28 at week 24 after RTX and identified patients not achieving LDA at week 24 with sensitivity of 93.3 % and specificity of 44.8 %.

CONCLUSIONS

A combination of LC and plasmablast frequency identifies patients with RA who will not benefit from RTX with high probability.

Autoantibodies From Single Circulating Plasmablasts React With Citrullinated Antigens and Porphyromonas gingivalis in Rheumatoid Arthritis

OBJECTIVE

Anti-citrullinated protein antibodies (ACPAs) are highly specific for rheumatoid arthritis (RA). However, the molecular basis for ACPA production is still unclear. The purpose of this study was to determine if circulating plasmablasts from RA patients produce ACPAs and whether Porphyromonas gingivalis facilitates the generation of ACPAs.

METHODS

Using a single-cell antibody cloning approach, we generated 217 and 110 monoclonal recombinant antibodies from circulating plasmablasts from 7 RA patients and 4 healthy controls, respectively. Antibody reactivity with citrullinated antigens was tested by a second-generation anti-cyclic citrullinated peptide (anti-CCP) kit and by enzyme-linked immunosorbent assays (ELISAs) against citrullinated human antigens. Antibody reactivity with P gingivalis was tested by ELISAs against outer membrane antigens (OMAs) and citrullinated enolase from P gingivalis.

RESULTS

Approximately 19.5% of plasmablast-derived antibodies from anti-CCP-positive RA patients, but none from 1 anti-CCP-negative RA patient or the healthy controls, specifically recognized citrullinated antigens. The immunoglobulin genes encoding these ACPAs were highly mutated, with increased ratios of replacement mutations to silent mutations, suggesting the involvement of active antigen selection in ACPA generation. Interestingly, 63% of the ACPAs cross-reacted with OMAs and/or citrullinated enolase from P gingivalis. The reactivity of ACPAs against citrullinated proteins from P gingivalis was confirmed by immunoblotting and mass spectrometry. Furthermore, some germline-reverted ACPAs retained their reactivity with P gingivalis antigens but completely lost their reactivity with citrullinated human antigens.

CONCLUSION

These results suggest that circulating plasmablasts in RA patients produce ACPAs and that this process may be facilitated by anti-P gingivalis immune responses.

Safety and tolerability of an anti-CD19 monoclonal antibody, MEDI-551, in subjects with systemic sclerosis: a phase I, randomized, placebo-controlled, escalating single-dose study

Background

Systemic sclerosis (SSc) is a clinically heterogeneous, life-threatening disease characterized by fibrosis, microvasculopathy, and autoimmunity. Extensive nonclinical and clinical data implicate B cells in the pathogenesis of SSc. MEDI-551 is an investigational humanized monoclonal antibody that targets the B cell surface antigen CD19 and mediates antibody-dependent, cell-mediated cytotoxicity of B cells. This clinical study evaluated the safety and tolerability, pharmacokinetics, and pharmacodynamics of MEDI-551 in subjects with SSc.

Methods

This phase I multicenter, randomized, double-blind, placebo-controlled, single escalating dose study enrolled adult subjects with either limited or diffuse cutaneous SSc. A single intravenous dose of MEDI-551 was administered, and safety and tolerability were evaluated. MEDI-551 pharmacokinetics (PK), pharmacodynamics, and immunogenicity were also assessed. Safety assessments included the incidence of adverse events and changes in clinical and laboratory results. MEDI-551 serum concentrations, effects on circulating and tissue B cells and plasma cells (PCs), and antidrug antibodies were analyzed. Modified Rodnan skin score (MRSS) and pulmonary function tests were used to explore the clinical effect of MEDI-551.

Results

The study enrolled 28 subjects with SSc (mean age, 47.3 years; 67.9 % female). Twenty-four received a single dose of MEDI-551 (0.1–10.0 mg/kg) and four received placebo. Treatment-emergent adverse events (TEAEs) occurred in 95.8 % of subjects in the MEDI-551 group and in 75.0 % of subjects in the placebo group; the majority of TEAEs were mild or moderate in severity. Two serious adverse events were considered possibly related to the study drug. One death, deemed not related to the study drug, occurred in a MEDI-551-treated subject. MEDI-551 exhibited linear PK in the dose range of 1.0 to 10.0 mg/kg, and more rapid clearance at lower doses. Dose-dependent depletion of circulating B cells and plasma cells was observed. MRSS assessments suggest a possible clinical effect of MEDI-551 on affected skin.

Conclusions

A single escalating dose of MEDI-551 was tolerable and safe in this subject population. B cell depletion was achieved and was dose dependent. A signal of clinical effect was observed. Based on these results, further investigation of MEDI-551 as a disease-modifying treatment for SSc is warranted.

Trial registration

www.clinicaltrials.gov identifier, NCT00946699; registered 23 July 2009.

Integrative genomic deconvolution of rheumatoid arthritis GWAS loci into gene and cell type associations

Background

Although genome-wide association studies (GWAS) have identified over 100 genetic loci associated with rheumatoid arthritis (RA), our ability to translate these results into disease understanding and novel therapeutics is limited. Most RA GWAS loci reside outside of protein-coding regions and likely affect distal transcriptional enhancers. Furthermore, GWAS do not identify the cell types where the associated causal gene functions. Thus, mapping the transcriptional regulatory roles of GWAS hits and the relevant cell types will lead to better understanding of RA pathogenesis.

Results

We combine the whole-genome sequences and blood transcription profiles of 377 RA patients and identify over 6000 unique genes with expression quantitative trait loci (eQTLs). We demonstrate the quality of the identified eQTLs through comparison to non-RA individuals. We integrate the eQTLs with immune cell epigenome maps, RA GWAS risk loci, and adjustment for linkage disequilibrium to propose target genes of immune cell enhancers that overlap RA risk loci. We examine 20 immune cell epigenomes and perform a focused analysis on primary monocytes, B cells, and T cells.

Conclusions

We highlight cell-specific gene associations with relevance to RA pathogenesis including the identification of FCGR2B in B cells as possessing both intragenic and enhancer regulatory GWAS hits. We show that our RA patient cohort derived eQTL network is more informative for studying RA than that from a healthy cohort. While not experimentally validated here, the reported eQTLs and cell type-specific RA risk associations can prioritize future experiments with the goal of elucidating the regulatory mechanisms behind genetic risk associations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-016-0948-6) contains supplementary material, which is available to authorized users.

[The significance of biobanks for clinical development]

Access to samples in biobanks and collection of samples for evaluation of biomarkers in clinical trials are an essential basis for the identification and development of biomarkers. From the perspective of a research-based pharmaceutical company identification of biomarkers and the accompanying diagnostics are an essential prerequisite for the further evolution of personalised healthcare-and the key to more effective and efficient healthcare. Research-based pharmaceutical companies can basically use four types of biobanks: biobanks of university hospitals, commercial providers, collaborative groups and company-owned biobanks. Areas of application, arising from the use of biobanks in the context of clinical development, are collection of prevalence data, evaluation of biomarker stability in different disease stages, technical validation of assays, an optimized course of clinical studies by focusing on defined, biomarker-stratified groups of patients and pharmacogenetic research. Challenges are, in particular, the availability of clinically annotated samples and tissue matching blood samples, in addition to sample quality, number and amount. An acceptable legal and regulatory framework, as well as the positive perception of biomarker data by politicians and the public, are important prerequisites for translational research for identification of biomarkers in clinical studies. Also, the early establishment of research alliances between academia and the pharmaceutical industry are required to transfer research results in new strategies for prevention, diagnosis and treatment of patients.

Biomarkers in Pharmaceutical Research

BACKGROUND

Biomarkers are important tools in drug development and are used throughout pharmaceutical research.

CONTENT

This review focuses on molecular biomarkers in drug development. It contains sections on how biomarkers are used to assess target engagement, pharmacodynamics, safety, and proof-of-concept. It also covers the use of biomarkers as surrogate end points and patient selection/companion diagnostics and provides insights into clinical biomarker discovery and biomarker development/validation with regulatory implications. To survey biomarkers used in drug development--acknowledging that many pharmaceutical development biomarkers are not published--we performed a focused PubMed search employing "biomarker" and the names of the largest pharmaceutical companies as keywords and filtering on clinical trials and publications in the last 10 years. This yielded almost 500 entries, the majority of which included disease-related (approximately 60%) or prognostic/predictive (approximately 20%) biomarkers. A notable portion (approximately 8%) included HER2 (human epidermal growth factor receptor 2) testing, highlighting the utility of biomarkers for patient selection. The remaining publications included target engagement, safety, and drug metabolism biomarkers. Oncology, cardiovascular disease, and osteoporosis were the areas with the most citations, followed by diabetes and Alzheimer disease.

SUMMARY

Judicious biomarker use can improve pharmaceutical development efficiency by helping to select patients most appropriate for treatment using a given mechanism, optimize dose selection, and provide earlier confidence in accelerating or discontinuing compounds in clinical development. Optimal application of biomarker technology requires understanding of candidate drug pharmacology, detailed modeling of biomarker readouts relative to pharmacokinetics, rigorous validation and qualification of biomarker assays, and creative application of these elements to drug development problems.

Expansion of Activated Peripheral Blood Memory B Cells in Rheumatoid Arthritis, Impact of B Cell Depletion Therapy, and Biomarkers of Response

Although B cell depletion therapy (BCDT) is effective in a subset of rheumatoid arthritis (RA) patients, both mechanisms and biomarkers of response are poorly defined. Here we characterized abnormalities in B cell populations in RA and the impact of BCDT in order to elucidate B cell roles in the disease and response biomarkers. In active RA patients both CD27+IgD- switched memory (SM) and CD27-IgD- double negative memory (DN) peripheral blood B cells contained significantly higher fractions of CD95+ and CD21- activated cells compared to healthy controls. After BCD the predominant B cell populations were memory, and residual memory B cells displayed a high fraction of CD21- and CD95+ compared to pre-depletion indicating some resistance of these activated populations to anti-CD20. The residual memory populations also expressed more Ki-67 compared to pre-treatment, suggesting homeostatic proliferation in the B cell depleted state. Biomarkers of clinical response included lower CD95+ activated memory B cells at depletion time points and a higher ratio of transitional B cells to memory at reconstitution. B cell function in terms of cytokine secretion was dependent on B cell subset and changed with BCD. Thus, SM B cells produced pro-inflammatory (TNF) over regulatory (IL10) cytokines as compared to naïve/transitional. Notably, B cell TNF production decreased after BCDT and reconstitution compared to untreated RA. Our results support the hypothesis that the clinical and immunological outcome of BCDT depends on the relative balance of protective and pathogenic B cell subsets established after B cell depletion and repopulation.

The quest for personalized B-cell depletion therapy in rheumatic disease

Although B cell depletion therapy (BCDT) is now a well-accepted therapeutic option in autoimmune rheumatic disease, a significant proportion of patients remain resistant to therapy. .19pt?>A more challenging clinical problem is the high rate of relapse after B cell reconstitution, as well as the difficulty in predicting the exact timing of that relapse. In this article, we consider the immunological mechanisms that may account for the heterogeneity of clinical response to BCDT. Understanding how BCDT alters the balance between different B cell subsets, some pathogenic and some regulatory, may help us correctly target BCDT to the right patients, and thereby improve treatment responses in rheumatic disease.

Plasmablasts as a biomarker for IgG4-related disease, independent of serum IgG4 concentrations

OBJECTIVES

We examined the utility of circulating total and IgG4+ plasmablasts as biomarkers of diagnosis and disease activity in IgG4-related disease (IgG4-RD).

MATERIALS METHODS

We evaluated patients with active, untreated, biopsy-proven IgG4-RD affecting various organs. Flow cytometry was used to measure total plasmablast and IgG4+ plasmablast counts by gating peripheral blood for CD19lowCD38+CD20-CD27+ cells and CD19lowCD38+CD20-CD27+IgG4+ cells. Serum IgG4 concentrations were measured by nephelometry. We compared 37 IgG4-RD patients to 35 controls, including healthy individuals (n=14) and patients with other inflammatory diseases before treatment (n=21).

RESULTS

The IgG4-RD patients' mean age was 59, and 68% were male. Fourteen patients (38%) had three or more organs involved. The IgG4-RD patients had substantially elevated total plasmablast counts (median 4698/mL, range 610-79524/mL) compared to both untreated disease controls (median 592/mL, range 19-4294/mL; p < 0.001) and healthy controls (median 94/mL, range 1-653/mL; p < 0.001). Thirteen IgG4-RD patients (36%) had normal serum IgG4 concentrations (mean 60 mg/dL, range 5-123 mg/dL, normal <135 mg/dL). However, the median plasmablast count was not significantly lower in that subset with normal serum IgG4 concentrations (3784/mL) compared to those with elevated serum IgG4 (5155/mL) (p = 0.242). Among the 12 rituximab (RTX)-treated patients, the median plasmablast level during disease flare was 6356/mL (range 1123-41589/mL), declining to 1419/mL (range 386/mL-4150/mL) during remission (p < 0.01).

CONCLUSIONS

Circulating plasmablasts are elevated in active IgG4-RD, even in patients with normal serum IgG4 concentrations. Plasmablast counts are a potentially useful biomarker for diagnosis, assessing response to treatment, and determining the appropriate time for re-treatment.

Sequencing the functional antibody repertoire--diagnostic and therapeutic discovery

The development of high-throughput DNA sequencing technologies has enabled large-scale characterization of functional antibody repertoires, a new method of understanding protective and pathogenic immune responses. Important parameters to consider when sequencing antibody repertoires include the methodology, the B-cell population and clinical characteristics of the individuals analysed, and the bioinformatic analysis. Although focused sequencing of immunoglobulin heavy chains or complement determining regions can be utilized to monitor particular immune responses and B-cell malignancies, high-fidelity analysis of the full-length paired heavy and light chains expressed by individual B cells is critical for characterizing functional antibody repertoires. Bioinformatic identification of clonal antibody families and recombinant expression of representative members produces recombinant antibodies that can be used to identify the antigen targets of functional immune responses and to investigate the mechanisms of their protective or pathogenic functions. Integrated analysis of coexpressed functional genes provides the potential to further pinpoint the most important antibodies and clonal families generated during an immune response. Sequencing antibody repertoires is transforming our understanding of immune responses to autoimmunity, vaccination, infection and cancer. We anticipate that antibody repertoire sequencing will provide next-generation biomarkers, diagnostic tools and therapeutic antibodies for a spectrum of diseases, including rheumatic diseases.

Long-term follow-up of patients who received repeat-dose rituximab as maintenance therapy for ANCA-associated vasculitis

OBJECTIVE

ANCA-associated vasculitis (AAV) is characterized by a chronic relapsing course. Rituximab (RTX) is an effective maintenance treatment; however, the long-term outcomes after its discontinuation are unclear. The aim of this study was to explore the long-term outcomes of AAV patients treated with repeat-dose RTX maintenance therapy.

METHODS

AAV patients receiving a RTX treatment protocol consisting of an induction and maintenance phase were included. For initial remission induction, RTX was dosed at 1 g every 2 weeks or 375 mg/m(2) weekly for 4 consecutive weeks and for remission maintenance at 1 g every 6 months for 24 months. At the first RTX administration, ongoing immunosuppressives were withdrawn.

RESULTS

Sixty-nine patients were identified, 67 of whom were failing other therapies. Nine relapsed during the RTX treatment protocol; however, all 69 were in remission at the end of the maintenance phase on a median prednisolone dose of 2.5 mg/day and 9% were receiving additional immunosuppression. During subsequent observation, 28 patients relapsed a median of 34.4 months after the last RTX infusion. Risk factors for relapse were PR3-associated disease (P = 0.039), B cell return within 12 months of the last RTX infusion (P = 0.0038) and switch from ANCA negativity to positivity (P = 0.0046). Two patients died and two developed severe hypogammaglobulinaemia.

CONCLUSION

This study supports the efficacy and safety of a fixed-interval RTX maintenance regimen in relapsing/refractory AAV. Relapses after discontinuation of maintenance therapy did occur, but at a lower rate than after a single RTX induction course. PR3-associated disease, the switch from ANCA negative to positive and the return of B cells within 12 months of the last RTX administration were risk factors for further relapse.

Barcode-enabled sequencing of plasmablast antibody repertoires in rheumatoid arthritis

OBJECTIVE

A hallmark of rheumatoid arthritis (RA) is the production of autoantibodies, including anti-citrullinated protein antibodies (ACPAs). Nevertheless, the specific targets of these autoantibodies remain incompletely defined. During an immune response, B cells specific for the inciting antigen(s) are activated and differentiate into plasmablasts, which are released into the blood. We undertook this study to sequence the plasmablast antibody repertoire to define the targets of the active immune response in RA.

METHODS

We developed a novel DNA barcoding method to sequence the cognate heavy- and light-chain pairs of antibodies expressed by individual blood plasmablasts in RA. The method uses a universal 5' adapter that enables full-length sequencing of the antibodies' variable regions and recombinant expression of the paired antibody chains. The sequence data sets were bioinformatically analyzed to generate phylogenetic trees that identify clonal families of antibodies sharing heavy- and light-chain VJ sequences. Representative antibodies were expressed, and their binding properties were characterized using anti-cyclic citrullinated peptide 2 (anti-CCP-2) enzyme-linked immunosorbent assay (ELISA) and antigen microarrays.

RESULTS

We used our sequencing method to generate phylogenetic trees representing the antibody repertoires of peripheral blood plasmablasts from 4 individuals with anti-CCP+ RA, and recombinantly expressed 14 antibodies that were either "singleton" antibodies or representative of clonal antibody families. Anti-CCP-2 ELISA identified 4 ACPAs, and antigen microarray analysis identified ACPAs that differentially targeted epitopes on α-enolase, citrullinated fibrinogen, and citrullinated histone H2B.

CONCLUSION

Our data provide evidence that autoantibodies targeting α-enolase, citrullinated fibrinogen, and citrullinated histone H2B are produced by the ongoing activated B cell response in, and thus may contribute to the pathogenesis of, RA.

PDL241, a novel humanized monoclonal antibody, reveals CD319 as a therapeutic target for rheumatoid arthritis

Introduction

Targeting the CD20 antigen has been a successful therapeutic intervention in the treatment of rheumatoid arthritis (RA). However, in some patients with an inadequate response to anti-CD20 therapy, a persistence of CD20^- plasmablasts is noted. The strong expression of CD319 on CD20^- plasmablast and plasma cell populations in RA synovium led to the investigation of the potential of CD319 as a therapeutic target.

Methods

PDL241, a novel humanized IgG₁ monoclonal antibody (mAb) to CD319, was generated and examined for its ability to inhibit immunoglobulin production from plasmablasts and plasma cells generated from peripheral blood mononuclear cells (PBMC) in the presence and absence of RA synovial fibroblasts (RA-SF). The in vivo activity of PDL241 was determined in a human PBMC transfer into NOD scid IL-2 gamma chain knockout (NSG) mouse model. Finally, the ability of PDL241 to ameliorate experimental arthritis was evaluated in a collagen-induced arthritis (CIA) model in rhesus monkeys.

Results

PDL241 bound to plasmablasts and plasma cells but not naïve B cells. Consistent with the binding profile, PDL241 inhibited the production of IgM from in vitro PBMC cultures by the depletion of CD319⁺ plasmablasts and plasma cells but not B cells. The activity of PDL241 was dependent on an intact Fc portion of the IgG₁ and mediated predominantly by natural killer cells. Inhibition of IgM production was also observed in the human PBMC transfer to NSG mouse model. Treatment of rhesus monkeys in a CIA model with PDL241 led to a significant inhibition of anti-collagen IgG and IgM antibodies. A beneficial effect on joint related parameters, including bone remodeling, histopathology, and joint swelling was also observed.

Conclusions

The activity of PDL241 in both in vitro and in vivo models highlights the potential of CD319 as a therapeutic target in RA.

Metabolic and safety issues for multiple sclerosis pharmacotherapy--opportunities for personalised medicine

INTRODUCTION

A number of disease-modifying therapies have become available to treat multiple sclerosis (MS) in recent years. As the effects of these medications are unpredictable and they are generally used for a number of years, the selection of the most appropriate disease-modifying agent must be based on the long-term efficacy and toxicity profile, thus strategies to personalise treatment to optimise responses may be potentially very useful.

AREAS COVERED

This review provides an overview of the efficacy and toxicity of disease-modifying agents used in MS and specifically discusses any metabolic side effects and advances in personalising the use of each of these agents. Medline and EMBASE were searched for any articles regarding the efficacy, toxicity and personalised use of the medicines discussed in this review.

EXPERT OPINION

Disease-modifying agents used to treat MS differ substantially in their efficacy and toxicity profile, but metabolic side effects appear to be limited to alemtuzumab, teriflunomide and IFN-β. Although personalised treatment strategies to assist in selection of the most appropriate disease-modifying agent for MS are limited, there is substantial potential to use genetic sub-studies of the many recent trials investigating disease-modifying agents to develop personalised treatment strategies.

De novo oligoclonal expansions of circulating plasmablasts in active and relapsing IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD) is a poorly understood, multiorgan, chronic inflammatory disease characterized by tumefactive lesions, storiform fibrosis, obliterative phlebitis, and accumulation of IgG4-expressing plasma cells at disease sites.

OBJECTIVE

The role of B cells and IgG4 antibodies in IgG4-RD pathogenesis is not well defined. We evaluated patients with IgG4-RD for activated B cells in both disease lesions and peripheral blood and investigated their role in disease pathogenesis.

METHODS

B-cell populations from the peripheral blood of 84 patients with active IgG4-RD were analyzed by using flow cytometry. The repertoire of B-cell populations was analyzed in a subset of patients by using next-generation sequencing. Fourteen of these patients were longitudinally followed for 9 to 15 months after rituximab therapy.

RESULTS

Numbers of CD19(+)CD27(+)CD20(-)CD38(hi) plasmablasts, which are largely IgG4(+), are increased in patients with active IgG4-RD. These expanded plasmablasts are oligoclonal and exhibit extensive somatic hypermutation, and their numbers decrease after rituximab-mediated B-cell depletion therapy; this loss correlates with disease remission. A subset of patients relapse after rituximab therapy, and circulating plasmablasts that re-emerge in these subjects are clonally distinct and exhibit enhanced somatic hypermutation. Cloning and expression of immunoglobulin heavy and light chain genes from expanded plasmablasts at the peak of disease reveals that disease-associated IgG4 antibodies are self-reactive.

CONCLUSIONS

Clonally expanded CD19(+)CD27(+)CD20(-)CD38(hi) plasmablasts are a hallmark of active IgG4-RD. Enhanced somatic mutation in activated B cells and plasmablasts and emergence of distinct plasmablast clones on relapse indicate that the disease pathogenesis is linked to de novo recruitment of naive B cells into T cell-dependent responses by CD4(+) T cells, likely driving a self-reactive disease process.

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.