Automated multi-scale computational pathotyping (AMSCP) of inflamed synovial tissue.

Rheumatoid arthritis (RA) is a complex immune-mediated inflammatory disorder in which patients suffer from inflammatory-erosive arthritis. Recent advances on histopathology heterogeneity of RA synovial tissue revealed three distinct phenotypes based on cellular composition (pauci-immune, diffuse and lymphoid), suggesting that distinct etiologies warrant specific targeted therapy which motivates a need for cost effective phenotyping tools in preclinical and clinical settings. To this end, we developed an automated multi-scale computational pathotyping (AMSCP) pipeline for both human and mouse synovial tissue with two distinct components that can be leveraged together or independently: (1) segmentation of different tissue types to characterize tissue-level changes, and (2) cell type classification within each tissue compartment that assesses change across disease states.

Clonal associations between lymphocyte subsets and functional states in rheumatoid arthritis synovium.

Rheumatoid arthritis (RA) is an autoimmune disease involving antigen-specific T and B cells. Here, we perform single-cell RNA and repertoire sequencing on paired synovial tissue and blood samples from 12 seropositive RA patients. We identify clonally expanded CD4 + T cells, including CCL5+ cells and T peripheral helper (Tph) cells, which show a prominent transcriptomic signature of recent activation and effector function.

B Cell-Directed Therapy in Autoimmunity.

Autoimmune diseases with B cell-directed therapeutics approved by the US Food and Drug Administration are surprisingly diverse in clinical manifestations and pathophysiology. In this review, we focus on recent clinical and mechanistic insights into the efficacy of B cell depletion in these diverse autoimmune disorders, the rapidly expanding armamentarium of approved agents, and future approaches. The pathogenic roles for B cells include direct functions such as production of autoantibodies and proinflammatory cytokines and indirect functions via antigen presentation to T cells.

Deconstruction of rheumatoid arthritis synovium defines inflammatory subtypes.

Rheumatoid arthritis is a prototypical autoimmune disease that causes joint inflammation and destruction. There is currently no cure for rheumatoid arthritis, and the effectiveness of treatments varies across patients, suggesting an undefined pathogenic diversity. Here, to deconstruct the cell states and pathways that characterize this pathogenic heterogeneity, we profiled the full spectrum of cells in inflamed synovium from patients with rheumatoid arthritis.

Clonal associations of lymphocyte subsets and functional states revealed by single cell antigen receptor profiling of T and B cells in rheumatoid arthritis synovium.

Rheumatoid arthritis (RA) is an autoimmune disease initiated by antigen-specific T cells and B cells, which promote synovial inflammation through a complex set of interactions with innate immune and stromal cells. To better understand the phenotypes and clonal relationships of synovial T and B cells, we performed single-cell RNA and repertoire sequencing on paired synovial tissue and peripheral blood samples from 12 donors with seropositive RA ranging from early to chronic disease. Paired transcriptomic-repertoire analyses highlighted 3 clonally distinct CD4 T cells populations that were enriched in RA synovium: T peripheral helper (Tph) and T follicular helper (Tfh) cells, CCL5+ T cells, and T regulatory cells (Tregs).

Granzyme K CD8 T cells form a core population in inflamed human tissue.

T cell-derived pro-inflammatory cytokines are a major driver of rheumatoid arthritis (RA) pathogenesis. Although these cytokines have traditionally been attributed to CD4 T cells, we have found that CD8 T cells are notably abundant in synovium and make more interferon (IFN)-γ and nearly as much tumor necrosis factor (TNF) as their CD4 T cell counterparts. Furthermore, using unbiased high-dimensional single-cell RNA-seq and flow cytometric data, we found that the vast majority of synovial tissue and synovial fluid CD8 T cells belong to an effector CD8 T cell population characterized by high expression of granzyme K (GzmK) and low expression of granzyme B (GzmB) and perforin.

Dynamic spectrum of ectopic lymphoid B cell activation and hypermutation in the RA synovium characterized by NR4A nuclear receptor expression.

Ectopic lymphoid structures (ELS) can develop in rheumatoid arthritis (RA) synovial tissue, but the precise pathways of B cell activation and selection are not well understood. Here, we identify a synovial B cell population characterized by co-expression of a family of orphan nuclear receptors (NR4A1-3), which is highly enriched in RA synovial tissue. A transcriptomic profile of NR4A synovial B cells significantly overlaps with germinal center light zone B cells and an accrual of somatic hypermutation that correlates with loss of naive B cell state.

B Cell Activation and Plasma Cell Differentiation Are Promoted by IFN-λ in Systemic Lupus Erythematosus.

Type I IFN is essential for viral clearance but also contributes to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE), via aberrant nucleic acid-sensing pathways, leading to autoantibody production. Type III IFN (IFN-λ) is now appreciated to have a nonredundant role in viral infection, but few studies have addressed the effects of IFN-λ on immune cells given the more restricted expression of its receptor primarily to the epithelium. In this study, we demonstrate that B cells display a prominent IFN gene expression profile in patients with lupus.

Defining inflammatory cell states in rheumatoid arthritis joint synovial tissues by integrating single-cell transcriptomics and mass cytometry.

To define the cell populations that drive joint inflammation in rheumatoid arthritis (RA), we applied single-cell RNA sequencing (scRNA-seq), mass cytometry, bulk RNA sequencing (RNA-seq) and flow cytometry to T cells, B cells, monocytes, and fibroblasts from 51 samples of synovial tissue from patients with RA or osteoarthritis (OA). Utilizing an integrated strategy based on canonical correlation analysis of 5,265 scRNA-seq profiles, we identified 18 unique cell populations. Combining mass cytometry and transcriptomics revealed cell states expanded in RA synovia: THY1(CD90)HLA-DRA sublining fibroblasts, IL1B pro-inflammatory monocytes, ITGAXTBX21 autoimmune-associated B cells and PDCD1 peripheral helper T (T) cells and follicular helper T (T) cells.

B cells inhibit bone formation in rheumatoid arthritis by suppressing osteoblast differentiation.

The function of B cells in osteoblast (OB) dysfunction in rheumatoid arthritis (RA) has not been well-studied. Here we show that B cells are enriched in the subchondral and endosteal bone marrow (BM) areas adjacent to osteocalcin OBs in two murine RA models: collagen-induced arthritis and the TNF-transgenic mice. Subchondral BM B cells in RA mice express high levels of OB inhibitors, CCL3 and TNF, and inhibit OB differentiation by activating ERK and NF-κB signaling pathways.

Methods for high-dimensional analysis of cells dissociated from cryopreserved synovial tissue.

Background: Detailed molecular analyses of cells from rheumatoid arthritis (RA) synovium hold promise in identifying cellular phenotypes that drive tissue pathology and joint damage. The Accelerating Medicines Partnership RA/SLE Network aims to deconstruct autoimmune pathology by examining cells within target tissues through multiple high-dimensional assays. Robust standardized protocols need to be developed before cellular phenotypes at a single cell level can be effectively compared across patient samples.

The TOG protein Stu2/XMAP215 interacts covalently and noncovalently with SUMO.

Stu2p is the yeast member of the XMAP215/Dis1/ch-TOG family of microtubule-associated proteins that promote microtubule polymerization. However, the factors that regulate its activity are not clearly understood. Here we report that Stu2p in the budding yeast Saccharomyces cerevisiae interacts with SUMO by covalent and noncovalent mechanisms.

Neutrophils Slow Disease Progression in Murine Lupus via Modulation of Autoreactive Germinal Centers.

Neutrophils are well characterized as mediators of peripheral tissue damage in lupus, but it remains unclear whether they influence loss of self-tolerance in the adaptive immune compartment. Lupus neutrophils produce elevated levels of factors known to fuel autoantibody production, including IL-6 and B cell survival factors, but also reactive oxygen intermediates, which can suppress lymphocyte proliferation. To assess whether neutrophils directly influence the progression of autoreactivity in secondary lymphoid organs (SLOs), we characterized the localization and cell-cell contacts of splenic neutrophils at several stages in the progression of disease in the NZB/W murine model of lupus.

Bone Marrow-Derived Mesenchymal Stem Cells From Patients With Systemic Lupus Erythematosus Have a Senescence-Associated Secretory Phenotype Mediated by a Mitochondrial Antiviral Signaling Protein-Interferon-β Feedback Loop.

Objective: Bone marrow-derived mesenchymal stem cells (BM-MSCs) create a special microenvironment for hematopoiesis and immunity and display robust immunomodulatory properties that are impaired in systemic lupus erythematosus (SLE). This study was undertaken to identify the mechanisms of defects in human SLE BM-MSCs.

Methods: Patients fulfilling SLE classification criteria and healthy controls (n = 6 per group) were recruited according to an institutional review board-approved protocol.

Production of RANKL by Memory B Cells: A Link Between B Cells and Bone Erosion in Rheumatoid Arthritis.

Objective: Rheumatoid arthritis (RA) is a systemic autoimmune disease that often leads to joint damage. The mechanisms of bone damage in RA are complex, involving activation of bone-resorbing osteoclasts (OCs) by synoviocytes and Th17 cells. This study was undertaken to investigate whether B cells play a direct role in osteoclastogenesis through the production of RANKL, the essential cytokine for OC development.

New insights into B cell biology in systemic lupus erythematosus and Sjögren's syndrome.

Purpose Of Review: Our understanding of the physiological and pathogenic functions of B cells in systemic lupus erythematosus (SLE) and Primary Sjögren's syndrome (pSS) continues to expand. In this review, we discuss novel insights published in the last 18 months into the roles of B cells in systemic autoimmunity.

Recent Findings: Data have continued to expand regarding the diverse mechanisms by which innate immune signals including Toll-like receptors (TLRs) regulate the B cell compartment.

Neutrophil-mediated IFN activation in the bone marrow alters B cell development in human and murine systemic lupus erythematosus.

Inappropriate activation of type I IFN plays a key role in the pathogenesis of autoimmune disease, including systemic lupus erythematosus (SLE). In this study, we report the presence of IFN activation in SLE bone marrow (BM), as measured by an IFN gene signature, increased IFN regulated chemokines, and direct production of IFN by BM-resident cells, associated with profound changes in B cell development. The majority of SLE patients had an IFN signature in the BM that was more pronounced than the paired peripheral blood and correlated with both higher autoantibodies and disease activity.

Effects of low-dose aspirin and fish oil on platelet function and NF-kappaB in adults with diabetes mellitus.

Introduction: Many diabetics are insensitive to aspirin's platelet anti-aggregation effects. The possible modulating effects of co-administration of aspirin and fish oil in subjects with diabetes are poorly characterized.

Participants And Methods: Thirty adults with type 2 diabetes mellitus were treated with aspirin 81 mg/d for 7 days, then with fish oil 4 g/day for 28 days, then the combination of fish oil and aspirin for another 7 days.

The yeast homologue of the microtubule-associated protein Lis1 interacts with the sumoylation machinery and a SUMO-targeted ubiquitin ligase.

Microtubules and microtubule-associated proteins are fundamental for multiple cellular processes, including mitosis and intracellular motility, but the factors that control microtubule-associated proteins (MAPs) are poorly understood. Here we show that two MAPs-the CLIP-170 homologue Bik1p and the Lis1 homologue Pac1p-interact with several proteins in the sumoylation pathway. Bik1p and Pac1p interact with Smt3p, the yeast SUMO; Ubc9p, an E2; and Nfi1p, an E3.

The combination of EPA+DHA and low-dose aspirin ingestion reduces platelet function acutely whereas each alone may not in healthy humans.

Introduction: Aspirin's effectiveness in reducing cardiovascular disease events is inadequate in some individuals, a phenomenon termed aspirin "resistance". The hypothesis that combining low dose aspirin with eicosapentaenoic acid and docosahexaenoic acid (EPA+DHA) reduces platelet function in the acute setting has not been investigated.

Patients And Methods: We conducted a clinical trial of EPA+DHA and aspirin ingestion in healthy adults.

Lpa2 is a negative regulator of both dendritic cell activation and murine models of allergic lung inflammation.

Negative regulation of innate immune responses is essential to prevent excess inflammation and tissue injury and promote homeostasis. Lysophosphatidic acid (LPA) is a pleiotropic lipid that regulates cell growth, migration, and activation and is constitutively produced at low levels in tissues and in serum. Extracellular LPA binds to specific G protein-coupled receptors, whose function in regulating innate or adaptive immune responses remains poorly understood.

Polyinosinic:polycytidylic acid induces protein kinase D-dependent disassembly of apical junctions and barrier dysfunction in airway epithelial cells.

Background: Disruption of the epithelial barrier might be a risk factor for allergen sensitization and asthma. Viral respiratory tract infections are strongly associated with asthma exacerbation, but the effects of respiratory viruses on airway epithelial barrier function are not well understood. Many viruses generate double-stranded RNA, which can lead to airway inflammation and initiate an antiviral immune response.

The effects of EPA, DHA, and aspirin ingestion on plasma lysophospholipids and autotaxin.

Lysophophatidylcholine (LPC) and lysophosphatidic acid (LPA) are potent lysolipid mediators increasingly linked with atherosclerosis and inflammation. A current model proposing that plasma LPA is produced when LPC is hydrolyzed by the enzyme autotaxin has not been rigorously investigated in human subjects. We conducted a clinical trial of eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) and aspirin ingestion in normal volunteers.

T-cell activation under hypoxic conditions enhances IFN-gamma secretion.

Secondary lymphoid organs and peripheral tissues are characterized by hypoxic microenvironments, both in the steady state and during inflammation. Although hypoxia regulates T-cell metabolism and survival, very little is known about whether or how hypoxia influences T-cell activation. We stimulated mouse CD4(+) T cells in vitro with antibodies directed against the T-cell receptor (CD3) and CD28 under normoxic (20% O(2)) and hypoxic (1% O(2)) conditions.