Association between peripheral activated naive and double negative 2 B-cell subsets and clinical parameters in lupus nephritis patients.

Altered composition of B-cell compartments is a known feature in patients with systemic lupus erythematosus (SLE). However, deep characterisation of B-cell subsets and their relation to clinical manifestations and disease activity in patients is limited. In this study, we analysed peripheral B-cell subsets phenotype in SLE (n = 35) and healthy controls (HCs, n = 15) by spectral flow cytometry.

Arthritis progressors have a decreased frequency of circulating autoreactive T cells during the at-risk phase of rheumatoid arthritis.

Objectives: The aim of this study was to combine deep T cell phenotyping with assessment of citrulline-reactive CD4+T cells in the pre-rheumatoid arthritis (RA) phase.

Methods: 20 anti-CCP2 positive individuals () presenting musculoskeletal complaints without clinical or ultrasound signs of synovitis; 10 arthritis progressors and 10 matched non-arthritis progressors were included. Longitudinal samples (1-3 time points) of peripheral blood mononuclear cells were assessed using HLA-class II tetramers with 12 different citrullinated candidate autoantigens combined in a >20-colour spectral flow cytometry panel.

The peculiar features, diversity and impact of citrulline-reactive autoantibodies.

Since entering the stage 25 years ago as a highly specific serological biomarker for rheumatoid arthritis, anti-citrullinated protein antibodies (ACPAs) have been a topic of extensive research. This hallmark B cell response arises years before disease onset, displays interpatient autoantigen variability, and is associated with poor clinical outcomes. Technological and scientific advances have revealed broad clonal diversity and intriguing features including high levels of somatic hypermutation, variable-domain N-linked glycosylation, hapten-like peptide interactions, and clone-specific multireactivity to citrullinated, carbamylated and acetylated epitopes.

Autoreactive B cells against malondialdehyde-induced protein cross-links are present in the joint, lung, and bone marrow of rheumatoid arthritis patients.

Autoantibodies to malondialdehyde (MDA) proteins constitute a subset of anti-modified protein autoantibodies in rheumatoid arthritis (RA), which is distinct from citrulline reactivity. Serum anti-MDA IgG levels are commonly elevated in RA and correlate with disease activity, CRP, IL6, and TNF-α. MDA is an oxidation-associated reactive aldehyde that together with acetaldehyde mediates formation of various immunogenic amino acid adducts including linear MDA-lysine, fluorescent malondialdehyde acetaldehyde (MAA)-lysine, and intramolecular cross-linking.

Occurrence and localization of FOXP3 + cells in kidney biopsies in lupus nephritis and ANCA-associated vasculitis.

The study aims to increase the understanding regarding the role of regulatory T cells (Tregs) in lupus nephritis (LN) and ANCA-associated vasculitis (AAV) by comparing their localization in renal tissue and changes following immunosuppressive therapy. Kidney biopsies from 12 patients with LN and 7 patients with AAV were examined. Kidney biopsies had been performed both at active disease and following immunosuppressive treatment.

Rheumatoid Arthritis-Specific Autoimmunity in the Lung Before and at the Onset of Disease.

Objective: The lung is implicated as a site for breach of tolerance prior to onset of seropositive rheumatoid arthritis (RA). To substantiate this, we investigated lung-resident B cells in bronchoalveolar lavage (BAL) samples from untreated early RA patients and anti-citrullinated protein antibody (ACPA)-positive individuals at risk for developing RA.

Methods: Single B cells (n = 7,680) were phenotyped and isolated from BAL samples from individuals at risk of RA (n = 3) and at RA diagnosis (n = 9).

Anti-Citrullinated Protein Antibody Reactivity towards Neutrophil-Derived Antigens: Clonal Diversity and Inter-Individual Variation.

Background: Why the adaptive immune system turns against citrullinated antigens in rheumatoid arthritis (RA) and whether anti-citrullinated protein antibodies (ACPAs) contribute to pathogenesis are questions that have triggered intense research, but still are not fully answered. Neutrophils may be crucial in this context, both as sources of citrullinated antigens and also as targets of ACPAs. To better understand how ACPAs and neutrophils contribute to RA, we studied the reactivity of a broad spectrum of RA patient-derived ACPA clones to activated or resting neutrophils, and we also compared neutrophil binding using polyclonal ACPAs from different patients.

The human bone marrow plasma cell compartment in rheumatoid arthritis - Clonal relationships and anti-citrulline autoantibody producing cells.

A majority of circulating IgG is produced by plasma cells residing in the bone marrow (BM). Long-lived BM plasma cells constitute our humoral immune memory and are essential for infection-specific immunity. They may also provide a reservoir of potentially pathogenic autoantibodies, including rheumatoid arthritis (RA)-associated anti-citrullinated protein autoantibodies (ACPA).

Identification of proteinase 3 autoreactive CD4T cells and their T-cell receptor repertoires in antineutrophil cytoplasmic antibody-associated vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is an autoimmune disease involving autoreactivity to proteinase 3 (PR3) as demonstrated by presence of ANCAs. While autoantibodies are screened for diagnosis, autoreactive T cells and their features are less well-studied. Here, we investigated PR3-specific CD4+T cell responses and features of autoreactive T cells in patients with PR3-AAV, using a cohort of 72 patients with either active or inactive disease.

Analysis of IGH allele content in a sample group of rheumatoid arthritis patients demonstrates unrevealed population heterogeneity.

Immunoglobulin heavy chain (IGH) germline gene variations influence the B cell receptor repertoire, with resulting biological consequences such as shaping our response to infections and altering disease susceptibilities. However, the lack of information on polymorphism frequencies in the IGH loci at the population level makes association studies challenging. Here, we genotyped a pilot group of 30 individuals with rheumatoid arthritis (RA) to examine IGH allele content and frequencies in this group.

A subset of antibodies targeting citrullinated proteins confers protection from rheumatoid arthritis.

Although elevated levels of anti-citrullinated protein antibodies (ACPAs) are a hallmark of rheumatoid arthritis (RA), the in vivo functions of these antibodies remain unclear. Here, we have expressed monoclonal ACPAs derived from patients with RA, and analyzed their functions in mice, as well as their specificities. None of the ACPAs showed arthritogenicity nor induced pain-associated behavior in mice.

Diversity and Clonality of T Cell Receptor Repertoire and Antigen Specificities in Small Joints of Early Rheumatoid Arthritis.

Objective: CD4+ T cells are implicated in rheumatoid arthritis (RA) pathology from the strong association between RA and certain HLA class II gene variants. This study was undertaken to examine the synovial T cell receptor (TCR) repertoire, T cell phenotypes, and T cell specificities in small joints of RA patients at time of diagnosis before therapeutic intervention.

Methods: Sixteen patients, of whom 11 patients were anti-citrullinated protein antibody (ACPA)-positive and 5 patients were ACPA-, underwent ultrasound-guided synovial biopsy of a small joint (n = 13) or arthroscopic synovial biopsy of a large joint (n = 3), followed by direct sorting of single T cells for paired sequencing of the αβ TCR together with flow cytometry analysis.

Five commercially-available antibodies react differentially with allelic forms of human HLA-DR beta chain.

Allelic variants of HLA-DRB1 have been associated with a variety of autoimmune and infectious diseases. Although the precise molecular mechanisms by which HLA-DRB1 alleles predispose to a particular disease are currently unclear, it has been shown that mRNA expression levels of HLA-DRB1 are dependent on the different alleles. We aimed to measure HLA-DR beta chain levels in peripheral blood mononuclear cells of individuals carrying HLA-DRB1*03:01/*04:01 and HLA-DRB1*03:01/*15:01 alleles by western blotting, using five commercially-available HLA-DRB antibodies.

Combination of Two Monoclonal Anti-Citrullinated Protein Antibodies Induced Tenosynovitis, Pain, and Bone Loss in Mice in a Peptidyl Arginine Deiminase-4-Dependent Manner.

Objective: The appearance of anti-citrullinated protein antibodies (ACPAs) in the circulation represents a major risk factor for developing rheumatoid arthritis (RA). Patient-derived ACPAs have been shown to induce pain and bone erosion in mice, suggesting an active role in the pathogenicity of RA. We undertook this study to investigate whether ACPAs can induce tenosynovitis, an early sign of RA, in addition to pain and bone loss and whether these symptoms are dependent on peptidyl arginine deiminase 4 (PAD4).

Integrated single cell and spatial transcriptomics reveal autoreactive differentiated B cells in joints of early rheumatoid arthritis.

B cells play a significant role in established Rheumatoid Arthritis (RA). However, it is unclear to what extent differentiated B cells are present in joint tissue already at the onset of disease. Here, we studied synovial biopsies (n = 8) captured from untreated patients at time of diagnosis.

Single cell sequencing identifies clonally expanded synovial CD4 T cells expressing GPR56 in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease affecting synovial joints where different CD4 T cell subsets may contribute to pathology. Here, we perform single cell sequencing on synovial CD4 T cells from anti-citrullinated protein antibodies (ACPA)+ and ACPA- RA patients and identify two peripheral helper T cell (T) states and a cytotoxic CD4 T cell subset. We show that the adhesion G-protein coupled receptor 56 (GPR56) delineates synovial CXCL13 T CD4 T cells expressing LAG-3 and the tissue-resident memory receptors CXCR6 and CD69.

Modulating T-cell activation with antisense oligonucleotides targeting lymphocyte cytosolic protein 2.

Dysregulated T-cell activation is a hallmark of several autoimmune diseases such as rheumatoid arthritis (RA) and multiple sclerosis (MS). The lymphocyte cytosolic protein 2 (LCP2), also known as SLP-76, is essential for the development and activation of T cells. Despite the critical role of LCP2 in T-cell activation and the need for developing drugs that modify T-cell activation, no LCP2 inhibitors have been developed.

Antibodies to a Citrullinated Epitope Are Increased in Early Rheumatoid Arthritis, and Can Be Produced by Gingival Tissue B Cells: Implications for a Bacterial Origin in RA Etiology.

Based on the epidemiological link between periodontitis and rheumatoid arthritis (RA), and the unique feature of the periodontal bacterium to citrullinate proteins, it has been suggested that production of anti-citrullinated protein antibodies (ACPA), which are present in a majority of RA patients, may be triggered in the gum mucosa. To address this hypothesis, we investigated the antibody response to a citrullinated peptide in relation to the autoimmune ACPA response in early RA, and examined citrulline-reactivity in monoclonal antibodies derived from human gingival B cells. Antibodies to a citrullinated peptide derived from (denoted CPP3) and human citrullinated peptides were analyzed by multiplex array in 2,807 RA patients and 372 controls; associations with RA risk factors and clinical features were examined.

Rituximab in Systemic Lupus Erythematosus: Transient Effects on Autoimmunity Associated Lymphocyte Phenotypes and Implications for Immunogenicity.

B cell abnormalities are common in systemic lupus erythematosus (SLE), and include expansion of double negative (DN) and age-associated-like B cells (ABC-like). We aimed to investigate rituximab (RTX) effects on DN and ABC-like B-cell subsets and, when possible, also secondary effects on T cells. Fifteen SLE patients, fulfilling the ACR 1982 criteria, starting RTX and followed longitudinally up to two years, were analyzed for B- and T- lymphocyte subsets using multicolor flow cytometry.

Three-dimensional spatial transcriptomics uncovers cell type localizations in the human rheumatoid arthritis synovium.

The inflamed rheumatic joint is a highly heterogeneous and complex tissue with dynamic recruitment and expansion of multiple cell types that interact in multifaceted ways within a localized area. Rheumatoid arthritis synovium has primarily been studied either by immunostaining or by molecular profiling after tissue homogenization. Here, we use Spatial Transcriptomics, where tissue-resident RNA is spatially labeled in situ with barcodes in a transcriptome-wide fashion, to study local tissue interactions at the site of chronic synovial inflammation.

Kidney infiltrating NK cells and NK-like T-cells in lupus nephritis: presence, localization, and the effect of immunosuppressive treatment.

Systemic lupus erythematosus (SLE) is a multi-organ inflammatory disease with kidney inflammation, lupus nephritis (LN), being one of the most severe manifestations. Immune complex deposits, particularly in glomeruli, and T cells, B cells, and myeloid cells, mainly with extraglomerular localization, contribute to the inflammatory process. Natural killer (NK) cells have been suggested to play a role in autoimmune diseases, but have not been investigated in detail in renal lupus before.