Rheumatoid arthritis macrophages are primed for inflammation and display bioenergetic and functional alterations.

Objectives: Myeloid cells with a monocyte/macrophage phenotype are present in large numbers in the RA joint, significantly contributing to disease; however, distinct macrophage functions have yet to be elucidated. This study investigates the metabolic activity of infiltrating polarized macrophages and their impact on pro-inflammatory responses in RA.

Methods: CD14+ monocytes from RA and healthy control (HC) bloods were isolated and examined ex vivo or following differentiation into 'M1/M2' macrophages.

Central Role of Semaphorin 3B in a Serum-Induced Arthritis Model and Reduced Levels in Patients With Rheumatoid Arthritis.

Objective: Semaphorin 3B (Sema3B) decreases the migratory and invasive capacities of fibroblast-like synoviocytes (FLS) in rheumatoid arthritis (RA) and suppresses expression of matrix metalloproteinases. We undertook this study to examine the role of Sema3B in a mouse model of arthritis and its expression in RA patients.

Methods: Clinical responses, histologic features, and FLS function were examined in wild-type (WT) and Sema3B mice in a K/BxN serum transfer model of arthritis.

ACPA Status Correlates with Differential Immune Profile in Patients with Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a progressive erosive autoimmune disease that affects 1% of the world population. Anti-citrullinated protein autoantibodies (ACPA) are routinely used for the diagnosis of RA, however 20-30% of patients are ACPA negative. ACPA status is a delineator of RA disease endotypes with similar clinical manifestation but potentially different pathophysiology.

Serum miRNA Signature in Rheumatoid Arthritis and "At-Risk Individuals".

Background: MicroRNAs (miRNAs) are small non-coding RNAs which have been implicated as potential biomarkers or therapeutic targets in autoimmune diseases. This study examines circulatory miRNAs in RA patients and further investigates if a serum miRNA signature precedes clinical manifestations of disease in arthralgia or "at-risk individuals".

Methods: Serum was collected from HC subjects (N = 20), RA patients (N = 50), and arthralgia subjects (N = 10), in addition to a subgroup of the RA patients post-methotrexate (MTX) (N = 18).

Rheumatoid arthritis CD14 monocytes display metabolic and inflammatory dysfunction, a phenotype that precedes clinical manifestation of disease.

Introduction: This study investigates the metabolic activity of circulating monocytes and their impact on pro-inflammatory responses in RA and explores whether this phenotype is already primed for inflammation before clinical manifestations of disease.

Methods: Blood was collected and CD14 monocytes isolated from healthy control donors (HC), individuals at-risk (IAR) and RA patients. Monocyte frequency in blood and synovial tissue was assessed by flow cytometry.

Serum MicroRNA Signature as a Diagnostic and Therapeutic Marker in Patients with Psoriatic Arthritis.

Objective: MicroRNA (miRNA) are small endogenous regulatory RNA molecules that have emerged as potential therapeutic targets and biomarkers in autoimmunity. Here, we investigated serum miRNA levels in patients with psoriatic arthritis (PsA) and further assessed a serum miRNA signature in therapeutic responder versus nonresponder PsA patients.

Methods: Serum samples were collected from healthy controls (HC; n = 20) and PsA patients (n = 31), and clinical demographics were obtained.

STAT3 Mediates the Differential Effects of Oncostatin M and TNFα on RA Synovial Fibroblast and Endothelial Cell Function.

Oncostatin M (OSM), a pleiotropic cytokine and a member of the gp130/IL-6 cytokine family, has been implicated in the pathogenesis of autoimmune diseases. Here we investigate the mechanisms by which its synergistic interactions with TNFα regulate the cellular bioenergetics and invasive function of synovial cells from patients with Rheumatoid Arthritis. Primary RA synovial fibroblasts (RAFLS) and human umbilical vein endothelial cells (HUVEC) were cultured with OSM alone or in combination with TNFα.

Dysregulated miR-125a promotes angiogenesis through enhanced glycolysis.

Background: Although neoangiogenesis is a hallmark of chronic inflammatory diseases such as inflammatory arthritis and many cancers, therapeutic agents targeting the vasculature remain elusive. Here we identified miR-125a as an important regulator of angiogenesis.

Methods: MiRNA levels were quantified in Psoriatic Arthritis (PsA) synovial-tissue by RT-PCR and compared to macroscopic synovial vascularity.

Association of synovial tissue polyfunctional T-cells with DAPSA in psoriatic arthritis.

Objective: This study examines polyfunctional T-cells in psoriatic arthritis (PsA) synovial tissue and their associations with clinical disease and implications for therapy.

Methods: PsA synovial tissue was enzymatically/mechanically digested to generate synovial tissue single cell suspensions. Frequencies of polyfunctional CD4, CD8, T-helper 1 (Th1), Th17 and exTh17 cells, using CD161 as a marker of Th17 plasticity, were determined by flow cytometry in matched PsA synovial tissue and peripheral blood.

Enriched Cd141+ DCs in the joint are transcriptionally distinct, activated, and contribute to joint pathogenesis.

CD141+ DC are implicated in antiviral and antitumor immunity. However, mechanistic studies in autoimmune disease are limited. This is the first study to our knowledge examining CD141+ DC in autoimmune disease, specifically inflammatory arthritis (IA).

Altered expression of microRNA-23a in psoriatic arthritis modulates synovial fibroblast pro-inflammatory mechanisms via phosphodiesterase 4B.

Objectives: To investigate the functional role of miR-23a in synovial fibroblasts (SFC) activation in psoriatic arthritis (PsA).

Methods: Differential expression of the miR-23a-27a-24-2 cluster was identified by real-time quantitative PCR in PsA synovial tissue and peripheral blood mononuclear cells (PBMC) compared to osteoarthritis (OA) and correlated with disease activity. For regulation experiments, PsA synovial fibroblasts (SFC) were cultured with Toll-like receptor (TLR) ligands and pro-inflammatory cytokines.

The Utility and Limitations of CRP, ESR and DAS28-CRP in Appraising Disease Activity in Rheumatoid Arthritis.

Identifying and quantifying inflammatory disease activity in rheumatoid arthritis remains a challenge. Many studies have suggested that a large proportion of patients may have active inflammation, but normal inflammatory markers. Although various disease activity scores have been validated, most rely to a large degree on biomarkers such as CRP and ESR.

Oxidative stress impairs energy metabolism in primary cells and synovial tissue of patients with rheumatoid arthritis.

Background: In this study, we examined the effect of oxidative stress on cellular energy metabolism and pro-angiogenic/pro-inflammatory mechanisms of primary rheumatoid arthritis synovial fibroblast cells (RASFC) and human umbilical vein endothelial cells (HUVEC).

Methods: Primary RASFC and HUVEC were cultured with the oxidative stress inducer 4-hydroxy-2-nonenal (4-HNE), and extracellular acidification rate, oxygen consumption rate, mitochondrial function and pro-angiogenic/pro-inflammatory mechanisms were assessed using the Seahorse analyser, complex I-V activity assays, random mutation mitochondrial capture assays, enzyme-linked immunosorbent assays and functional assays, including angiogenic tube formation, migration and invasion. Expression of angiogenic growth factors in synovial tissue (ST) was assessed by IHC in patients with rheumatoid arthritis (RA) undergoing arthroscopy before and after administration of tumour necrosis factor inhibitors (TNFi).

JAK/STAT Blockade Alters Synovial Bioenergetics, Mitochondrial Function, and Proinflammatory Mediators in Rheumatoid Arthritis.

Objective: To examine the effects of tofacitinib on metabolic activity, mitochondrial function, and proinflammatory mechanisms in rheumatoid arthritis (RA).

Methods: Ex vivo RA synovial explants and primary RA synovial fibroblasts (RASFs) were cultured with 1 μM tofacitinib. RASF bioenergetics were assessed using an XF24 analyzer, and key metabolic genes were assessed by reverse transcription-polymerase chain reaction (RT-PCR) analysis.

Hypoxia, oxidative stress and inflammation.

Inflammatory Arthritis is characterized by synovial proliferation, neovascularization and leukocyte extravasation leading to joint destruction and functional disability. Efficiency of oxygen supply to the synovium is poor due to the highly dysregulated synovial microvasculature. This along with the increased energy demands of activated infiltrating immune cells and inflamed resident cells leads to an hypoxic microenvironment and mitochondrial dysfunction.

Immune checkpoint inhibitor PD-1 pathway is down-regulated in synovium at various stages of rheumatoid arthritis disease progression.

Immune checkpoint blockade with therapeutic anti-cytotoxic T lymphocyte-associated antigen (CTLA)-4 (Ipilimumab) and anti-programmed death (PD)-1 (Nivolumab and Pembrolizumab) antibodies alone or in combination has shown remarkable efficacy in multiple cancer types, concomitant with immune-related adverse events, including arthralgia and inflammatory arthritis (IA) in some patients. Herein, using Nivolumab (anti-PD-1 antagonist)-responsive genes along with transcriptomics of synovial tissue from multiple stages of rheumatoid arthritis (RA) disease progression, we have interrogated the activity status of PD-1 pathway during RA development. We demonstrate that the expression of PD-1 was increased in early and established RA synovial tissue compared to normal and OA synovium, whereas that of its ligands, programmed death ligand-1 (PD-L1) and PD-L2, was increased at all the stages of RA disease progression, namely arthralgia, IA/undifferentiated arthritis, early RA and established RA.

Corrigendum: Synovial tissue research: a state-of-the-art review.

This corrects the article DOI: 10.1038/nrrheum.2017.

Synovial tissue research: a state-of-the-art review.

This corrects the article DOI: 10.1038/nrrheum.2017.

Synovial Immunophenotype and Anti-Citrullinated Peptide Antibodies in Rheumatoid Arthritis Patients: Relationship to Treatment Response and Radiologic Prognosis.

Objective: Serum anti-citrullinated peptide antibodies (ACPAs) may be present before the development of rheumatoid arthritis (RA) and may be predictive of more severe, erosive disease. This study was undertaken to examine the synovial tissue immunophenotype according to ACPA status in patients with RA, as well as the response to treatment and erosion status.

Methods: Consecutive RA patients were prospectively recruited and underwent clinical and serologic assessments before and after treatment.

Synovial tissue research: a state-of-the-art review.

The synovium is the major target tissue of inflammatory arthritides such as rheumatoid arthritis. The study of synovial tissue has advanced considerably throughout the past few decades from arthroplasty and blind needle biopsy to the use of arthroscopic and ultrasonographic technologies that enable easier visualization and improve the reliability of synovial biopsies. Rapid progress has been made in using synovial tissue to study disease pathogenesis, to stratify patients, to discover biomarkers and novel targets, and to validate therapies, and this progress has been facilitated by increasingly diverse and sophisticated analytical and technological approaches.

CD40L-Dependent Pathway Is Active at Various Stages of Rheumatoid Arthritis Disease Progression.

The inflammatory CD40-CD40L pathway is implicated in various autoimmune diseases, but the activity status of this pathway in various stages of rheumatoid arthritis (RA) progression is unknown. In this study, we used gene signatures of CD40L stimulation derived from human immature dendritic cells and naive B cells to assess the expression of CD40-downstream genes in synovial tissues from anti-citrullinated protein Ab-positive arthralgia, undifferentiated arthritis (UA), early RA, and established RA cohorts in comparison with healthy donors. Interestingly, the expression of and active full-length was increased in the disease tissues, whereas that of a dominant-negative isoform was decreased.

Resolution of TLR2-induced inflammation through manipulation of metabolic pathways in Rheumatoid Arthritis.

During inflammation, immune cells activated by toll-like receptors (TLRs) have the ability to undergo a bioenergetic switch towards glycolysis in a manner similar to that observed in tumour cells. While TLRs have been implicated in the pathogenesis of rheumatoid arthritis (RA), their role in regulating cellular metabolism in synovial cells, however, is still unknown. In this study, we investigated the effect of TLR2-activation on mitochondrial function and bioenergetics in primary RA-synovial fibroblast cells (RASFC), and further determined the role of glycolytic blockade on TLR2-induced inflammation in RASFC using glycolytic inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3PO).

Acute serum amyloid A is an endogenous TLR2 ligand that mediates inflammatory and angiogenic mechanisms.

Introduction: Acute-phase serum amyloid A (A-SAA) has cytokine-like properties and is expressed at sites of inflammation. We examined whether A-SAA-induced pro-inflammatory mechanisms are mediated through Toll-like receptor 2 (TLR2) in rheumatoid arthritis (RA).

Methods: The effect of A-SAA on human embryonic kidney (HEK), TLR2 or TLR4 cells was quantified by nuclear factor (NF)-κB luciferase reporter assays.