Integration of multi-omics analysis reveals metabolic alterations of B lymphocytes in systemic lupus erythematosus.

OBJECTIVE: To link changes in the B-cell transcriptome from systemic lupus erythematosus (SLE) patients with those in their macroenvironment, including cellular and fluidic components. METHODS: Analysis was performed on 363 patients and 508 controls, encompassing transcriptomics, metabolomics, and clinical data. B-cell and whole-blood transcriptomes were analysed using DESeq and GSEA. Plasma and urine metabolomics peak changes were quantified and annotated using Ceu Mass Mediator database. Common sources of variation were identified using MOFA integration analysis. RESULTS: Cellular macroenvironment was enriched in cytokines, stress responses, lipidic synthesis/mobility pathways and nucleotide degradation. B cells shared these pathways, except nucleotide degradation diverted to nucleotide salvage pathway, and distinct glycosylation, LPA receptors and Schlafen proteins. CONCLUSIONS: B cells showed metabolic changes shared with their macroenvironment and unique changes directly or indirectly induced by IFN-α signalling. This study underscores the importance of understanding the interplay between B cells and their macroenvironment in SLE pathology.

Molecular characterisation of lupus low disease activity state (LLDAS) and DORIS remission by whole-blood transcriptome-based pathways in a pan-European systemic lupus erythematosus cohort.

OBJECTIVES: To unveil biological milieus underlying low disease activity (LDA) and remission versus active systemic lupus erythematosus (SLE). METHODS: We determined differentially expressed pathways (DEPs) in SLE patients from the PRECISESADS project (NTC02890121) stratified into patients fulfilling and not fulfilling the criteria of (1) Lupus LDA State (LLDAS), (2) Definitions of Remission in SLE remission, and (3) LLDAS exclusive of remission. RESULTS: We analysed data from 321 patients; 40.8% were in LLDAS, and 17.4% in DORIS remission. After exclusion of patients in remission, 28.3% were in LLDAS. Overall, 604 pathways differed significantly in LLDAS versus non-LLDAS patients with an false-discovery rate-corrected p (q)<0.05 and a robust effect size (dr)≥0.36. Accordingly, 288 pathways differed significantly between DORIS remitters and non-remitters (q<0.05 and dr≥0.36). DEPs yielded distinct molecular clusters characterised by differential serological, musculoskeletal, and renal activity. Analysis of partially overlapping samples showed no DEPs between LLDAS and DORIS remission. Drug repurposing potentiality for treating SLE was unveiled, as were important pathways underlying active SLE whose modulation could aid attainment of LLDAS/remission, including toll-like receptor (TLR) cascades, Bruton tyrosine kinase (BTK) activity, the cytotoxic T lymphocyte antigen 4 (CTLA-4)-related inhibitory signalling, and the nucleotide-binding oligomerization domain leucine-rich repeat-containing protein 3 (NLRP3) inflammasome pathway. CONCLUSIONS: We demonstrated for the first time molecular signalling pathways distinguishing LLDAS/remission from active SLE. LLDAS/remission was associated with reversal of biological processes related to SLE pathogenesis and specific clinical manifestations. DEP clustering by remission better grouped patients compared with LLDAS, substantiating remission as the ultimate treatment goal in SLE; however, the lack of substantial pathway differentiation between the two states justifies LLDAS as an acceptable goal from a biological perspective.

CD8+ tissue-resident memory T cells are expanded in primary Sjögren's disease and can be therapeutically targeted by CD103 blockade.

OBJECTIVE: Tissue-resident memory cells (Trm) are a subset of T cells residing persistently and long-term within specific tissues that contribute to persistent inflammation and tissue damage. We characterised the phenotype and function of Trm and the role of CD103 in primary Sjogren's syndrome (pSS). METHODS: In both pSS and non-pSS sicca syndrome patients, we examined Trm frequency, cytokine production in salivary glands (SG) and peripheral blood (PB). We also analysed Trm-related gene expression in SG biopsies through bulk and single-cell RNA sequencing (scRNAseq). Additionally, we investigated Trm properties in an immunisation-induced animal model of pSS (experimental SS, ESS) mouse model and assessed the effects of Trm inhibition via intraglandular anti-CD103 monoclonal antibody administration. RESULTS: Transcriptomic pSS SG showed an upregulation of genes associated with tissue recruitment and long-term survival of Trm cells, confirmed by a higher frequency of CD8+CD103+CD69+ cells in pSS SG, compared with non-specific sialadenitis (nSS). In SG, CD8+ CD103+ Trm contributed to the secretion of granzyme-B and interferon-γ, CD8+ Trm cells were localised within inflammatory infiltrates, where PD1+CD8+ T cells were also increased compared with nSS and MALT lymphoma. scRNAseq of PB and pSS SG T cells confirmed expression of CD69, ITGAE, GZMB, GZMK and HLA-DRB1 among CD3+CD8+ SG T cells. In the SG of ESS, CD8+CD69+CD103+ Trm producing Granzyme B progressively expanded. However, intraglandular blockade of CD103 in ESS reduced Trm, reduced glandular damage and improved salivary flow. CONCLUSIONS: CD103+CD8+Trm cells are expanded in the SG of pSS and ESS, participate in tissue inflammation and can be therapeutically targeted.

Regulatory B cells are reduced in the blood in patients with granulomatosis with polyangiitis, and fail to regulate T-cell IFN-γ production.

Regulatory B (Breg) cells can dampen inflammation, autoreactivity, and transplant rejection. We investigated the frequencies, phenotypes, and function of Breg cells in granulomatosis with polyangiitis (GPA) to gain further knowledge as to whether there are numerical alterations or limitations of their ability to regulate T-cell function. Frequencies and phenotypes of CD24hiCD27+ and CD24hiCD38hi B-cells in the blood were determined with flow cytometry in 37 GPA patients (22 in remission and 15 with active disease) and 31 healthy controls (HC). A co-culture model was used to study the capacity of Breg cells to regulate T-cell activation and proliferation in cells from 10 GPA patients in remission and 12 HC. T-cell cytokine production in vitro and levels in plasma were determined with enzyme-linked immunosorbent assay. Frequencies of CD24hiCD27+ B-cells were reduced both during active disease and remission compared with HC (P = 0.005 and P = 0.010, respectively), whereas CD24hiCD38hi B-cells did not differ. Patient CD24hiCD27+ B-cells exhibited decreased expression of CD25 but increased expression of PD-L1 and PD-L2 during remission. B-cells from GPA patients regulated T-cell proliferation but failed to regulate interferon (IFN)-γ production (median T-cells alone 222 ng/ml vs. T-cells + B-cells 207 ng/ml, P = 0.426). IFN-γ was also elevated in patient plasma samples (P = 0.016). In conclusion, GPA patients exhibit altered numbers and phenotypes of CD24hiCD27+ B-cells. This is accompanied by a disability to control T-cell production of Th1-type cytokines during remission, which might be of fundamental importance for the granulomatous inflammation that characterizes the chronic phase of this disease.

High-content multimodal analysis supports the IL-7/IL-7 receptor axis as a relevant therapeutic target in primary Sjögren's syndrome.

OBJECTIVE: While the involvement of IL-7/IL-7R axis in pSS has been described in relation to T cells, little is known about the contribution of this pathway in relationship with other immune cells, and its implication in autoimmunity. Using high-content multiomics data, we aimed at characterizing IL-7R expressing cells and the involvement of IL-7/IL-7R pathway in pSS pathophysiology. METHODS: An IL-7 signature established using RNA-sequencing of human PBMCs incubated with IL-7 was applied to 304 pSS patients, and on RNA-Seq datasets from tissue biopsies. High-content immunophenotyping using flow and imaging mass cytometry was developed to characterize peripheral and in situ IL-7R expression. RESULTS: We identified a blood 4-gene IL-7 module (IKZF4, KIAA0040, PGAP1 and SOS1) associated with anti-SSA/Ro positiveness in patients as well as disease activity, and a tissue 5-gene IL-7 module (IL7R, PCED1B, TNFSF8, ADAM19, MYBL1) associated with infiltration severity. We confirmed expression of IL-7R on T cells subsets, and further observed upregulation of IL-7R on double-negative (DN) B cells, and especially DN2 B cells. IL-7R expression was increased in pSS compared to sicca patients with variations seen according to the degree of infiltration. When expressed, IL-7R was mainly found on epithelial cells, CD4+ and CD8+ T cells, switched memory B cells, DN B cells and M1 macrophages. CONCLUSION: This exhaustive characterization of the IL-7/IL-7R pathway in pSS pathophysiology established that two IL-7 gene modules discriminate pSS patients with a high IL-7 axis involvement. Their use could guide the implementation of an anti-IL-7R targeted therapy in a precision medicine approach.

Identification of potential salivary biomarkers for Sjögren's syndrome with an untargeted metabolomic approach.

INTRODUCTION: Despite the rise of metabolomics over the past years, and particularly salivary metabolomics, little research on Sjögren's syndrome (SS) biomarkers has focused on the salivary metabolome. OBJECTIVES: This study aims to identify metabolites that could be used as biomarkers for SS. METHODS: Using the software called XCMS online, the salivary metabolic profiles obtained with liquid chromatography coupled to high-resolution mass spectrometry for 18 female SS patients were compared to those obtained for 22 age-matched female healthy controls. RESULTS AND CONCLUSION: A total of 91 metabolites showed differential expression in SS patients. A putative identification was proposed with the use of a database for 37 of these metabolites and, of these, 16 identifications were confirmed. Given the identified metabolites, some important metabolic pathways, such as amino acid metabolism, purine metabolism, or even the citric acid cycle seem to be affected. Through the analyses of the ROC (receiver operating characteristic) curves, three metabolites, namely alanine, isovaleric acid, and succinic acid, showed both good sensitivity (respectively 1.000, 1.000, and 0.750) and specificity (respectively 0.692, 0.615, and 0.692) for identifying SS and could then be interesting biomarkers for a potential salivary diagnosis test.

Abatacept Promotes Regulatory B Cell Functions, Enhancing Their Ability to Reduce the Th1 Response in Rheumatoid Arthritis Patients through the Production of IL-10 and TGF-ß.

Abatacept mimics natural CD152 and competes with CD28 for binding to CD80/CD86 on APC, such as B cells, thereby preventing T cell activation. However, its potential impact on B cells has not been identified. The aim of this study was to assess whether abatacept can potentiate the immunoregulatory properties of B cells in vitro and in patients with rheumatoid arthritis (RA). T and B cells from healthy controls were purified. The suppressor properties of B cells in the presence of abatacept or control IgG1 were evaluated based on the ability of these cells to inhibit the polyclonal expansion (anti-CD3/CD28 stimulation) of T cells or their differentiation into Th1 or Th17 cells. Similar analyses were also performed with cells from RA patients before and 3 mo after abatacept initiation. Abatacept significantly potentiated regulatory B cell regulatory functions by enhancing their ability to produce IL-10 and TGF-ß, resulting in the increased generation of regulatory T cells and limited T cell proliferation and differentiation into Th1 and Th17 cells. Interestingly, B cells isolated from patients that received a 3-mo treatment with abatacept had an increased ability to reduce T cell functions, confirming the above observations. Abatacept binding to CD80/CD86 induces and promotes regulatory B cell functions by enhancing the ability of these cells to produce IL-10 and TGF-ß in vitro and in RA patients.

Update on B Cell Response in Periodontitis.

B cells have a central and dual role in the physio-pathological mechanisms of periodontitis. They take part in the elimination of the periodontal germs, the induction of tissue destructions and the regulation of the immune response. B cells play an essential role in the destruction of alveolar bone in periodontitis by immunomodulation, rather than by production of antibodies. In the periodontal cell network, B cells are in constant interaction with other immune cells and mesenchymal cells. Periodontitis is characterized by a cellular conversion from a dominant T-cell lesion to a dominant B-cell lesion, particularly enriched in plasma cells. This evolution results from abnormal interactions between B and T cells in periodontitis. Moreover, B cells are at the crossroads of the immune and the bone systems and are involved in the autoimmune mechanisms described in periodontitis. Different subsets of B cells are involved in periodontal destruction, in particular memory B cells, plasma cells and B1 cells. Effector memory B cells strongly express mRANKL in periodontitis and constitute the precursors of plasma cells. B1 cells are also involved in tissue destruction but also in the mechanisms of regulation, in particular via the natural secretion of IL-10 by CD11b+ B1 cells which form a part of the B10 cells that regulate the inflammatory response. As such, periodontitis seems to be associated with a deficit in regulation. In peripheral blood, B cells can also be systemic markers of infection and periodontal inflammation: circulating memory B cells are increased in periodontitis while circulating CD11b+ B1 cells are decreased. The study of B cells in periodontitis is constantly evolving for a better knowledge of the periodontitis setting, the evaluation and the follow-up of periodontitis, but also for the design of new therapeutic targets that may be promising in the management of severe periodontitis.

The diversity of the plasmablast signature across species and experimental conditions: A meta-analysis.

Antibody-secreting cells (ASC) are divided into two principal subsets, including the long-lived plasma cell (PC) subset residing in the bone marrow and the short-lived subset, also called plasmablast (PB). PB are described as a proliferating subset circulating through the blood and ending its differentiation in tissues. Due to their inherent heterogeneity, the molecular signature of PB is not fully established. The purpose of this study was to decipher a specific PB signature in humans and mice through a comprehensive meta-analysis of different data sets exploring the PB differentiation in both species and across different experimental conditions. The present study used recent analyses using whole RNA sequencing in prdm1-GFP transgenic mice to define a reliable and accurate PB signature. Next, we performed similar analysis using current data sets obtained from human PB and PC. The PB-specific signature is composed of 155 and 113 genes in mouse and human being, respectively. Although only nine genes are shared between the human and mice PB signature, the loss of B-cell identity such as the down-regulation of PAX5, MS4A1, (CD20) CD22 and IL-4R is a conserved feature across species and across the different experimental conditions. Additionally, we observed that the IRF8 and IRF4 transcription factors have a specific dynamic range of expression in human PB. We thus demonstrated that IRF4/IRF8 intranuclear staining was useful to define PB in vivo and in vitro and able to discriminate between atypical PB populations and transient states.

B cells in Sjögren's syndrome: from pathophysiology to therapeutic target.

Biological abnormalities associated with B lymphocytes are a hallmark of patients with primary Sjögren's syndrome. Those patients present abnormal distribution of B lymphocytes in peripheral blood and B cells in exocrine glands. B cells produce auto-antibodies, cytokines and present antigens but can also suppressive functions. In this review, we will summarize current knowledge on B cells in primary Sjögren's syndrome patients, demonstrate their critical role in the immunopathology of the disease and describe the past and current trials targeting B cells.

Glatiramer Acetate Stimulates Regulatory B Cell Functions.

The control of the activities of regulatory B (Breg) cells in immune disorders is an emerging therapeutic strategy for the recovery of immune homeostasis. Manipulating B cells using numerous drugs in vivo affect their regulatory functions, although a direct link has not yet been demonstrated. Glatiramer acetate (GA) is a synthetic polypeptide that is used in the treatment of inflammatory and autoimmune diseases. We experimented on an in vitro coculture system to determine its direct effects on the Breg cell properties of human B cells. We found that GA improves the B cell-dependent control of T cells' immune responses. When B cells are stimulated by GA, the T cell proliferation and their Th1 IFN-γ production are further inhibited, whereas the B cell production of IL-10 is further enhanced. GA binds preferentially to the memory B cells and the activation of sorted B cell subsets shows that GA-dependent increased Breg cell activities are specifically supported by the B cells' memory compartment. Moreover, we found that the defective regulations that emerge from the B cells of systemic lupus erythematosus patients can be restored by GA stimulation. Overall, these data demonstrate that GA stimulates the Breg functions mainly by shifting the memory B cells known to contribute to the T cell-dependent inflammatory response into Breg cells. Our results also indicate that GA treatment could be a useful therapy for recovering the Breg cells in autoimmune situations in which their activities are defective.

Treatment of Sjögren's Syndrome with Mesenchymal Stem Cells: A Systematic Review.

Mesenchymal stem cells (MSCs) are ubiquitous in the human body. Mesenchymal stem cells were initially isolated from bone marrow and later from other organs such as fatty tissues, umbilical cords, and gingiva. Their secretory capacities give them interesting immunomodulatory properties in cell therapy. Some studies have explored the use of MSCs to treat Sjögren's syndrome (SS), a chronic inflammatory autoimmune disease that mainly affects exocrine glands, including salivary and lacrimal glands, although current treatments are only palliative. This systematic review summarizes the current data about the application of MSCs in SS. Reports show improvements in salivary secretions and a decrease in lymphocytic infiltration in salivary glands in patients and mice with SS after intravenous or infra-peritoneal injections of MSCs. MSC injections led to a decrease in inflammatory cytokines and an increase in anti-inflammatory cytokines. However, the intrinsic mechanism of action of these MSCs currently remains unknown.

Hyposialylation Must Be Considered to Develop Future Therapies in Autoimmune Diseases.

Autoimmune disease development depends on multiple factors, including genetic and environmental. Abnormalities such as sialylation levels and/or quality have been recently highlighted. The adjunction of sialic acid at the terminal end of glycoproteins and glycolipids is essential for distinguishing between self and non-self-antigens and the control of pro- or anti-inflammatory immune reactions. In autoimmunity, hyposialylation is responsible for chronic inflammation, the anarchic activation of the immune system and organ lesions. A detailed characterization of this mechanism is a key element for improving the understanding of these diseases and the development of innovative therapies. This review focuses on the impact of sialylation in autoimmunity in order to determine future treatments based on the regulation of hyposialylation.

Genome-wide whole blood transcriptome profiling in a large European cohort of systemic sclerosis patients.

OBJECTIVES: The analysis of annotated transcripts from genome-wide expression studies may help to understand the pathogenesis of complex diseases, such as systemic sclerosis (SSc). We performed a whole blood (WB) transcriptome analysis on RNA collected in the context of the European PRECISESADS project, aiming at characterising the pathways that differentiate SSc from controls and that are reproducible in geographically diverse populations. METHODS: Samples from 162 patients and 252 controls were collected in RNA stabilisers. Cases and controls were divided into a discovery (n=79+163; Southern Europe) and validation cohort (n=83+89; Central-Western Europe). RNA sequencing was performed by an Illumina assay. Functional annotations of Reactome pathways were performed with the Functional Analysis of Individual Microarray Expression (FAIME) algorithm. In parallel, immunophenotyping of 28 circulating cell populations was performed. We tested the presence of differentially expressed genes/pathways and the correlation between absolute cell counts and RNA transcripts/FAIME scores in regression models. Results significant in both populations were considered as replicated. RESULTS: Overall, 15 224 genes and 1277 functional pathways were available; of these, 99 and 225 were significant in both sets. Among replicated pathways, we found a deregulation in type-I interferon, Toll-like receptor cascade, tumour suppressor p53 protein function, platelet degranulation and activation. RNA transcripts or FAIME scores were jointly correlated with cell subtypes with strong geographical differences; neutrophils were the major determinant of gene expression in SSc-WB samples. CONCLUSIONS: We discovered a set of differentially expressed genes/pathways validated in two independent sets of patients with SSc, highlighting a number of deregulated processes that have relevance for the pathogenesis of autoimmunity and SSc.

Can artificial intelligence replace manual search for systematic literature? Review on cutaneous manifestations in primary Sjögren's syndrome.

OBJECTIVES: Manual systematic literature reviews are becoming increasingly challenging due to the sharp rise in publications. The primary objective of this literature review was to compare manual and computer software using artificial intelligence retrieval of publications on the cutaneous manifestations of primary SS, but we also evaluated the prevalence of cutaneous manifestations in primary SS. METHODS: We compared manual searching and searching with the in-house computer software BIbliography BOT (BIBOT) designed for article retrieval and analysis. Both methods were used for a systematic literature review on a complex topic, i.e. the cutaneous manifestations of primary SS. Reproducibility was estimated by computing Cohen's κ coefficients and was interpreted as follows: slight, 0-0.20; fair, 0.21-0.40; moderate, 0.41-0.60; substantial, 0.61-0.80; and almost perfect, 0.81-1. RESULTS: The manual search retrieved 855 articles and BIBOT 1042 articles. In all, 202 articles were then selected by applying exclusion criteria. Among them, 155 were retrieved by both methods, 33 by manual search only, and 14 by BIBOT only. Reliability (κ = 0.84) was almost perfect. Further selection was performed by reading the 202 articles. Cohort sizes and the nature and prevalence of cutaneous manifestations varied across publications. In all, we found 52 cutaneous manifestations reported in primary SS patients. The most described ones were cutaneous vasculitis (561 patients), xerosis (651 patients) and annular erythema (215 patients). CONCLUSION: Among the final selection of 202 articles, 155/202 (77%) were found by the two methods but BIBOT was faster and automatically classified the articles in a chart. Combining the two methods retrieved the largest number of publications.

New criteria and new methodological tools for devising criteria sets of inflammatory rheumatic diseases.

Rheumatologists use classification criteria to separate patients with inflammatory rheumatic diseases (IRD). They change over time, and the concepts of the diseases also change. The paradigm is currently moving as the goal of classification in the future will be more to select which patients may be relevant for a specific treatment rather than to describe their characteristics. Therefore, the challenge will be to reclassify multifactorial diseases on the basis of their biological mechanisms rather than their clinical phenotype. Currently, various projects are trying to reclassify diseases using bioinformatics approaches and in the near future the use of advanced machine learning algorithms with large omics datasets could lead to new classification models not only based on a clinical phenotype but also on complex biological profile and common sensitivity to targeted treatment. These models would highlight common biological pathways between patients classified in the same cluster and provide a deep understanding of the mechanisms involved in the patient's clinical phenotype. Such approaches would ultimately lead to classification models that rely more on biological causes than on symptoms. This overview on current classification of subgroups of IRD summarises the classification criteria that we use routinely, and how we will classify IRD in the future using bioinformatics and artificial intelligence techniques.

Human regulatory B cells control the TFH cell response.

BACKGROUND: Follicular helper T (TFH) cells support terminal B-cell differentiation. Human regulatory B (Breg) cells modulate cellular responses, but their control of TFH cell-dependent humoral immune responses is unknown. OBJECTIVE: We sought to assess the role of Breg cells on TFH cell development and function. METHODS: Human T cells were polyclonally stimulated in the presence of IL-12 and IL-21 to generate TFH cells. They were cocultured with B cells to induce their terminal differentiation. Breg cells were included in these cultures, and their effects were evaluated by using flow cytometry and ELISA. RESULTS: B-cell lymphoma 6, IL-21, inducible costimulator, CXCR5, and programmed cell death protein 1 (PD-1) expressions increased on stimulated human T cells, characterizing TFH cell maturation. In cocultures they differentiated B cells into CD138+ plasma and IgD-CD27+ memory cells and triggered immunoglobulin secretions. Breg cells obtained by Toll-like receptor 9 and CD40 activation of B cells prevented TFH cell development. Added to TFH cell and B-cell cocultures, they inhibited B-cell differentiation, impeded immunoglobulin secretions, and expanded Foxp3+CXCR5+PD-1+ follicular regulatory T cells. Breg cells modulated IL-21 receptor expressions on TFH cells and B cells, and their suppressive activities involved CD40, CD80, CD86, and intercellular adhesion molecule interactions and required production of IL-10 and TGF-ß. CONCLUSION: Human Breg cells control TFH cell maturation, expand follicular regulatory T cells, and inhibit the TFH cell-mediated antibody secretion. These novel observations demonstrate a role for the Breg cell in germinal center reactions and suggest that deficient activities might impair the TFH cell-dependent control of humoral immunity and might lead to the development of aberrant autoimmune responses.

Cell-specific epigenome-wide DNA methylation profile in long-term cultured minor salivary gland epithelial cells from patients with Sjögren's syndrome.

OBJECTIVES: The aetiology of primary Sjögren's syndrome (pSS), also referred to as autoimmune epithelitis, is incompletely understood but includes an epigenetic contribution. Accordingly, the aim of this study was to investigate DNA methylation in salivary gland epithelial cells (SGEC), and to compare results with those publicly available from pSS B and T cells. METHODS: Long-term cultured SGEC were selected to conduct an epigenome-wide association study (EWAS) in patients with pSS with comparison to controls using the HumanMethylation 450 K array from Illumina. RESULTS: The analysis of differentially methylated CpG (DMC) uncovered 4662 positions corresponding to 2560 genes, and 575 genes with two or more DMC sites (DMCs), in SGEC as compared with controls. Further analysis highlighted an important proportion of interferon-regulated genes (61%), the calcium pathway (hypomethylated) and the Wnt pathway (hypermethylated). When comparing SGEC with pSS T and/or B cell results, an important overlap was observed with respect to differentially methylated genes (38.8%) and pSS risk factors (71.4%), although such assertion was not true when comparing DMCs. CONCLUSIONS: This study conducted in SGEC emphasises the role of DNA methylation in pSS pathogenesis and supports the necessity to conduct pure cell analysis for future EWAS studies when analysing salivary glands from patients with pSS.

Identification and phenotyping of circulating autoreactive proteinase 3-specific B cells in patients with PR3-ANCA associated vasculitis and healthy controls.

OBJECTIVES: To develop a method to detect and phenotype circulating proteinase 3 (PR3)-specific B-cells in patients with PR3-ANCA associated vasculitis (AAV). METHODS: Recombinant human PR3 (rPR3) was tagged with FITC or biotin, and its binding characteristics were studied by flow cytometry using three hybridoma cell lines secreting antibodies (Ab) against human PR3, mouse PR3 (no cross-reactivity with human PR3), and human neutrophil elastase. We measured the proportion of PR3-specific B-cells and studied their surface phenotype in patients with PR3-AAV and healthy controls (HC). RESULTS: Labeled rPR3 efficiently and specifically bound to hybridoma cells producing anti-human-PR3-Ab but not anti-mouse-PR3-Ab or anti-human-elastase-Ab. The proportion of rPR3-stained B cells was higher in patients with PR3-AAV compared to HCs: median (IQR) 1.11% (0.81-2.43) vs 0.45% (0.26-0.62) respectively, p < 0.001. There was a trend towards a higher proportion of PR3-specific B cells among patients with active disease compared to patients in remission: 2.91% (1.18-6.52) vs 0.99% (0.72-1.58), p = 0.09. In HCs, the proportion of PR3-specific B cells was highest among the transitional B-cell subset, and decreased with the maturation of B cells. Conversely, in patients, the proportion of PR3-specific B cells progressively increased with the maturation of B cells (median 1.90% of naïve B cells, 2.30% of unswitched memory B cells, 2.37% of switched memory B cells, and 3.68% of plasmablasts). CONCLUSIONS: Circulating PR3-specific B cells can be detected in HC and patients with PR3-AAV. Their progressive enrichment during B-cell maturation suggests that they are actively selected and escape peripheral tolerance checkpoints in patients.

Correction of abnormal B-cell subset distribution by interleukin-6 receptor blockade in polymyalgia rheumatica.

Objectives: The aim was to study lymphocyte subsets and circulating cytokines at diagnosis of PMR and after tocilizumab monotherapy. Methods: Eighteen untreated patients with PMR were included in a prospective study and received 3-monthly tocilizumab infusions without glucocorticoids. Lymphocyte subset distribution was assessed by flow cytometry and serum cytokines were assayed by a 34-cytokine array and ELISA, at baseline and during follow-up. Baseline data were also compared with age- and sex-matched controls. Results: At baseline, total lymphocytes, T-cell subsets and NK cell counts were similar in patients and controls, but patients had significantly lower B-cell counts attributable to lower transitional, naïve and post-switch memory B-cell subsets. Circulating B-cell counts were positively correlated with the PMR activity score (PMR-AS) in untreated active patients at baseline, but subsequently increased to normal values while disease activity was controlled after tocilizumab therapy. Among serum cytokines, IL-6 showed the largest concentration difference between patients and controls, and the serum IL-6 concentration was correlated with baseline PMR-AS. The effects of tocilizumab on serum IL-6 concentration were heterogeneous, and the patients whose serum IL-6 decreased after tocilizumab therapy exhibited a significant increase in circulating B-cell counts. Conclusion: In patients with PMR, B-cell lymphopenia and abnormal B-cell subset distribution are associated with disease activity and IL-6 concentration, and both are corrected by the IL-6 antagonist tocilizumab.