Paired Rheumatoid Arthritis Synovial Biopsies From Small and Large Joints Show Similar Global Transcriptomic Patterns With Enrichment of Private Specificity TCRB and TCR Signaling Pathways

Identification the role of necroptosis in rheumatoid arthritis by WGCNA network

Rheumatoid arthritis (RA) is the predominant manifestation of inflammatory arthritis, distinguished by an increasing burden of morbidity and mortality. The intricate interplay of genes and signalling pathways involved in synovial inflammation in patients with RA remains inadequately comprehended. This study aimed to ascertain the role of necroptosis in RA, as along with their associations with immune cell infiltration. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were employed to identify central genes for RA. In this study, identified total of 28 differentially expressed genes (DEGs) were identified in RA. Utilising WGCNA, two co-expression modules were generated, with one module demonstrating the strongest correlation with RA. Through the integration of differential gene expression analysis, a total of 5 intersecting genes were discovered. These 5 hub genes, namely fused in sarcoma (FUS), transformer 2 beta homolog (TRA2B), eukaryotic translation elongation factor 2 (EEF2), cleavage and polyadenylation specific factor 6 (CPSF6) and signal transducer and activator of transcription 3 (STAT3) were found to possess significant diagnostic value as determined by receiver operating characteristic (ROC) curve analysis. The close association between the concentrations of various immune cells is anticipated to contribute to the diagnosis and treatment of RA. Furthermore, the infiltration of immune cells mentioned earlier is likely to exert a substantial influence on the initiation of this disease.

Analysis of synovitis patterns in early RA supports the importance of joint-specific factors

BACKGROUND

Rheumatoid arthritis (RA) is classically considered a systemic disorder, but the role of local factors in driving synovial inflammation is increasingly being recognized. These joint-specific factors may consequently modulate disease phenotype.

OBJECTIVES

Our goal was to study the spatial distribution of swelling, tenderness and erosions in a large cohort of early RA (ERA) patients, to assess for patterns of simultaneously-involved joint clusters. We also aimed to investigate the link between arthritis localization and phenotypic features such as bone erosions and response to methotrexate therapy.

METHODS

DMARD-naive patients from the ERA UCLouvain Brussels cohort were included. Forty-four joints were clinically assessed for swelling and tenderness before treatment, and 6 months later for methotrexate-treated patients. Clusters of joints were identified using Principal component analysis and Cramer's correlation coefficients. Frequency of bone erosions and joint-specific response to methotrexate were compared across different clusters.

RESULTS

452 ERA patients were included. Analysis of the spatial distribution of swelling and tenderness allowed for the identification of 3 joint clusters that showed significant simultaneous involvement: (i) MTP1-5 joints, (ii) hand joints (MCPs and PIPs), and (iii) larger joints. These clusters were associated with different susceptibility to bone erosions and distinct clinical features, but similar local response (joint swelling resolution) to methotrexate.

CONCLUSION

This is the first study investigating the spatial distribution of arthritis in a large cohort of early RA using an unbiased approach. We identify clusters of simultaneously involved joints, supporting the importance of local factors in driving synovitis in RA.

Characteristics of T-Cell Receptor Repertoire for Differential Response to Methotrexate Treatment for Rheumatoid Arthritis

BACKGROUND

Methotrexate (MTX) serves as the initial treatment for rheumatoid arthritis (RA). However, a substantial proportion of RA patients, estimated between 30% and 50%, do not respond positively to MTX. While the T-cell receptor (TCR) is crucial for the immune response during RA, its role in differentiating MTX responsiveness has not been thoroughly investigated.

METHODS

This study used next-generation sequencing to analyze the TCR β-chain complementary determining region sequences in peripheral blood mononuclear cells obtained from RA patients before MTX treatment. This study aimed to compare the characteristics of the TCR repertoire between the MTX responder and non-responder groups.

RESULTS

The study identified a significant difference in the TRBV6-6 gene (p = .003) concerning MTX treatment response. Additionally, a significant difference was found in the number of "3" nucleotide deletions at the 5'Jdels site (p = .023) in the VDJ rearrangement.

CONCLUSION

These findings suggest distinct TCR repertoire characteristics between MTX responder and non-responder groups among RA patients. This discovery offers new insights into understanding the variable responses of RA patients to MTX therapy.

Clinical implications of synovial tissue phenotypes in rheumatoid arthritis

Autoimmune forms of inflammatory arthritis, such as Rheumatoid Arthritis (RA), are clinically heterogeneous in presentation and disease course. Treatment-related outcomes vary despite patient exposure to similar treatment strategies. It is likely that variation seen in synovial pathogenesis influences outcomes and is heterogeneous outcomes influenced by patient factors, including environmental exposures, microbiota, behaviors, timely access to therapy, and synovial cell variation. Patients' unique complex factors manifest as specific synovial phenotypes characterized by clusters of synovial cell types and states. Precision medicine aims to use such clinical and biological data to identify the right treatment for the right patient at the right time, enabling patients to achieve sustained remission. Identifying synovial targets susceptible to a given treatment, enabling the choice of effective therapy for a given patient, will realize the goals of precision medicine. Over the last 7 years, improved acquisition and processing of synovial tissue obtained by ultra-sound guided biopsy has enabled researchers to define synovial pathotypes using histologic features and predominant cell types associated with clinical manifestations. Technical advances have enabled single-cell simultaneous sequencing of proteins and gene expression that, through increasingly sophisticated bioinformatics methods, have taken transcriptional and proteomic data to identify diverse and novel cell types and states that cluster in the RA synovium to further define patient subgroups. Synovial pathotypes and endotypes are now integrated into clinical studies and trials to explain clinical heterogeneity in disease course and treatment response. Rapidly evolving clinical-translational research has linked an expanded understanding of RA synovial pathogenesis with clinically meaningful subgroups and treatment outcomes and the clinical heterogeneity in RA.

Patterns and determinants of response to novel therapies in juvenile and adult-onset polyarthritis

Biologic and targeted synthetic DMARDs (b/tsDMARDs) have revolutionized the management of multiple rheumatic inflammatory conditions. Among these, polyarticular JIA (pJIA) and RA display similarities in terms of disease pathophysiology and response pattern to b/tsDMARDs. Indeed, the therapeutic efficacy of novel targeted drugs is variable among individual patients, in both RA and pJIA. The mechanisms and determinants of this heterogeneous response are diverse and complex, such that the development of true 'precision'-medicine strategies has proven highly challenging. In this review, we will discuss pathophysiological, patient-specific, drug-specific and environmental factors contributing to individual therapeutic response in pJIA in comparison with what is known in RA. Although some biomarkers have been identified that stratify with respect to the likelihood of either therapeutic response or non-response, few have proved useful in clinical practice so far, likely due to the complexity of treatment-response mechanisms. Consequently, we propose a pragmatic, patient-centred and clinically based approach, i.e. personalized instead of biomarker-based precision medicine in JIA.

Diagnostic and prognostic role of synovial tissue analysis in juvenile idiopathic arthritis: a monocentric study

OBJECTIVES

This study investigates the diagnostic role of synovial tissue analysis in children presenting with arthritis and assesses its prognostic significance to predict clinical outcome in juvenile idiopathic arthritis (JIA).

METHODS

Synovial samples of paediatric patients undergoing synovial biopsy between 1995 and 2020 were analysed histologically and immunohistochemically. Relationships between histological/immunohistochemical parameters and clinical variables were assessed.

RESULTS

Synovial biopsy was performed for diagnosis in 65 cases allowing to correctly classify 79% of patients.At histological analysis on 42 JIA samples, any difference in the number of synovial lining layers, subsynovial elementary lesions, fibrin deposit, Krenn Synovitis Score, inflammatory infiltrate score and pattern emerged between JIA subsets or on treatment exposure. Synovial tissue analysis predicted outcome: higher number of synovial layers predicted worse disease course (>4 flares during follow-up; 4.5 vs 3.0, p=0.035), even after adjusting for age at diagnosis and observation time (OR 2.2, p=0.007); subjects who had switched>2 biological disease-modifying antirheumatic drugs had higher prevalence of subsynovial elementary lesions (55.6% vs 10.3%, p=0.005) and fibrin deposits in synovial lining (60.0% vs 22.6%, p=0.049), even after adjustment for observation time and age at diagnosis (OR 8.1, p=0.047). At immunohistochemistry on 31 JIA samples, higher CD3 expression was described in polyarticular compared with oligoarticular subset (p=0.040). Patients with severe disease course had higher CD20+ rate (OR 7, p=0.023), regardless of JIA subset and treatment exposure.

CONCLUSIONS

Synovial tissue analysis might support the clinicians in the diagnostic approach of paediatric patients presenting with arthritis and guide the clinical management in JIA.

Disease activity drives transcriptomic heterogeneity in early untreated rheumatoid synovitis

OBJECTIVES

Transcriptomic profiling of synovial tissue from patients with early, untreated rheumatoid arthritis (RA) was used to explore the ability of unbiased, data-driven approaches to define clinically relevant subgroups.

METHODS

RNASeq was performed on 74 samples, with disease activity data collected at inclusion. Principal components analysis (PCA) and unsupervised clustering were used to define patient clusters based on expression of the most variable genes, followed by pathway analysis and inference of relative abundance of immune cell subsets. Histological assessment and multiplex immunofluorescence (for CD45, CD68, CD206) were performed on paraffin sections.

RESULTS

PCA on expression of the (n=894) most variable genes across this series did not divide samples into distinct groups, instead yielding a continuum correlated with baseline disease activity. Two patient clusters (PtC1, n=52; PtC2, n=22) were defined based on expression of these genes. PtC1, with significantly higher disease activity and probability of response to methotrexate therapy, showed upregulation of immune system genes; PtC2 showed upregulation of lipid metabolism genes, described to characterise tissue resident or M2-like macrophages. In keeping with these data, M2-like:M1-like macrophage ratios were inversely correlated with disease activity scores and were associated with lower synovial immune infiltration and the presence of thinner, M2-like macrophage-rich synovial lining layers.

CONCLUSION

In this large series of early, untreated RA, we show that the synovial transcriptome closely mirrors clinical disease activity and correlates with synovial inflammation. Intriguingly, lower inflammation and disease activity are associated with higher ratios of M2:M1 macrophages, particularly striking in the synovial lining layer. This may point to a protective role for tissue resident macrophages in RA.

Ferroptosis-Related Molecular Clusters and Diagnostic Model in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by synovitis, joint damage and deformity. A newly described type of cell death, ferroptosis, has an important role in the pathogenesis of RA. However, the heterogeneity of ferroptosis and its association with the immune microenvironment in RA remain unknown. Synovial tissue samples from 154 RA patients and 32 healthy controls (HCs) were obtained from the Gene Expression Omnibus database. Twelve of twenty-six ferroptosis-related genes (FRGs) were differentially expressed between RA patients and HCs. Furthermore, the patterns of correlation among the FRGs were significantly different between the RA and HC groups. RA patients were classified into two distinct ferroptosis-related clusters, of which cluster 1 had a higher abundance of activated immune cells and a corresponding lower ferroptosis score. Enrichment analysis suggested that tumor necrosis factor-α signaling via nuclear factor-κB was upregulated in cluster 1. RA patients in cluster 1 responded better to anti-tumor necrosis factor (anti-TNF) therapy, which was verified by the GSE 198520 dataset. A diagnostic model to identify RA subtypes and immunity was constructed and verified, in which the area under the curve values in the training (70%) and validation (30%) cohorts were 0.849 and 0.810, respectively. This study demonstrated that there were two ferroptosis clusters in RA synovium that exhibited distinct immune profiles and ferroptosis sensitivity. Additionally, a gene scoring system was constructed to classify individual RA patients.

Identification of key candidate genes and pathways in rheumatoid arthritis and osteoarthritis by integrated bioinformatical analysis

Rheumatoid arthritis (RA) and osteoarthritis (OA) are the most common joint disorders. Although they have shown analogous clinical manifestations, the pathogenesis of RA and OA are different. In this study, we used the online Gene Expression Omnibus (GEO) microarray expression profiling dataset GSE153015 to identify gene signatures between RA and OA joints. The relevant data on 8 subjects obtained from large joints of RA patients (RA-LJ), 8 subjects obtained from small joints of RA patients (RA-SJ), and 4 subjects with OA were investigated. Differentially expressed genes (DEGs) were screened. Functional enrichment analysis of DEGs including the Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified, which were mainly associated with T cell activation or chemokine activity. Besides, protein-protein interaction (PPI) network analysis was performed, and key modules were identified. Hub genes of RA-LJ and OA groups were screened, they were CD8A, GZMB, CCL5, CD2, and CXCL9, whereas CD8A, CD2, IL7R, CD27, and GZMB were hub genes of RA-SJ and OA group. The novel DEGs and functional pathways between RA and OA identified in this study may provide new insight into the underlying molecular mechanisms and therapeutic strategies of RA and OA.

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. TCRs from expanded CD4+ T cell clones of 4 patients carrying an HLA-DRB1*04:01 allele were artificially reexpressed to study antigen specificity.

RESULTS

T cell analysis demonstrated CD4+ dominance and the presence of peripheral helper T-like cells in both patient groups. We identified >4,000 unique TCR sequences, as well as 225 clonal expansions. Additionally, T cells with double α-chains were a recurring feature. We identified a biased gene usage of the V_β chain segment TRBV20-1 in CD4+ cells from ACPA+ patients. In vitro stimulation of T cell lines expressing selected TCRs with an extensive panel of citrullinated and viral peptides identified several different virus-specific TCRs (e.g., human cytomegalovirus and human herpesvirus 2). Still, the majority of clones remained orphans with unknown specificity.

CONCLUSION

Minimally invasive biopsies of the RA synovium allow for single-cell TCR sequencing and phenotyping. Clonally expanded, viral-reactive T cells account for part of the diverse CD4+ T cell repertoire. TRBV20-1 bias in ACPA+ patients suggests recognition of common antigens.

Expression of LINC00638 in rheumatoid arthritis patients with damp-heat obstruction syndrome and the regulatory mechanisms for inflammation and oxidative stress

OBJECTIVES

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and joint destruction. Both inflammatory response and oxidative stress contribute to the pathogenesis of RA. Oxidative damage can induce and aggravate the imbalance of immune inflammation and promote cell and tissue damage. In this study, the expression of long non-coding RNA (lncRNA) LINC00638 in peripheral blood of patients with RA damp-heat arthralgia syndrome was observed, and the correlation between LINC00638 and disease activity, immune inflammation and oxidative stress indicator was investigated. Subsequently, the mechanisms for LINC00638 in regulating the inflammatory response and oxidative stress in RA fibroblast-like synoviocyte (FLS) under the condition of overexpression and interference were further explored.

METHODS

In this study, 48 RA patients with damp-heat arthralgia syndrome and 27 normal healthy subjects, who came from Department of Rheumatology, First Affiliated Hospital of Anhui University of Chinese Medicine, were included; and they were divided into a RA group and a control group. The expression of LINC00638 in peripheral blood mononuclear cells (PBMC) from the subjects was detected by real-time PCR. Enzyme linked immunosorbent assay (ELISA) was used to detect serum interleukin (IL)-10, IL-17, tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), heme oxygenase 1 (HO-1) and superoxide dismutase 2 (SOD2) expression. Spearman method was used to study the relationship between LINC00638 and erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptide antibody (anti-CCP), and to observe the relation between LINC00638 and the Disease Activity Score of 28 Joint (DAS28), Quantitative Score of Damp Heat Syndrome, Visual Analogue Scale (VAS), Self-rating Anxiety Scale (SAS) and Self-rating Depression Scale (SDS). RA-FLS was induced by RA-PBMC, and the RA in vitro cell experimental model was established. LINC00638 overexpression plasmid and small interfering RNA (siRNA) were constructed and transfected into RA-FLS. The cell experiments were divided into 4 groups: a pcDNA3. 1- control group, a pcDNA3.1-LINC00638 group, a siRNA-control group, and a siRNA-LINC00638 group. The transfection efficiency of overexpression plasmid and siRNA was detected by real-time PCR, the expression of TNF-α and IL-10 was detected by ELISA, and the expression of antioxidant proteins HO-1 and SOD2 was detected by immunofluorescence.

RESULTS

Compared with the control group, the expression of LINC00638 in the RA group was lower (P<0.01). The area under the curve (AUC) of the receiver operating characteristic (ROC) curve of LINC00638 was 0.9271. The DAS28 in RA group was 5.70 (5.40-6.50), the Quantitative Score of Damp-heat Syndrome was 20.0 (17.0-23.0), and the VAS score was 7.0 (6.3-8.0). Compared with the control group, the ESR, CRP, RF, anti-CCP, SAS and SDS scores in the RA group were significantly increased (all P<0.01). Spearman correlation analysis showed that: LINC00638 was negatively correlated with ESR (r=-0.532, P<0.01), CRP (r=-0.367, P<0.05), TNF-α (r=-0.375, P<0.01), MDA (r= -0.295, P<0.05), DAS28 (r=-0.450, P<0.01), and which was positively correlated with SOD2 (r=0.370, P<0.05). After the induction of RA-FLS, the expression level of LINC00638 was significantly decreased (P<0.01), indicating that the stimulation of PBMC could effectively reduce the expression of LINC00638 in RA-FLS, so the experimental model of RA-FLS-induced by PBMC was utilized. Compared with the pcDNA3.1-control group, the expressions of LINC00638, IL-10, SOD2, and HO-1 in the pcDNA3.1-LINC00638 group were significantly increased (all P<0.01), and the expression of TNF-α was decreased (P<0.01). Compared with siRNA-control group, LINC00638, IL-10, SOD2 and HO-1 in the siRNA-LINC00638 group were significantly decreased (all P<0.01), and TNF-α was significantly increased (P<0.01).

CONCLUSIONS

LINC00638 is down-regulated in the peripheral blood of RA patients with damp-heat arthralgia syndrome, which is correlated with disease activity, immune inflammation and oxidative stress. Overexpression of LINC00638 can down-regulate pro-inflammatory factors, up-regulate anti-inflammatory factors, and increase antioxidant enzyme activity, thereby improving inflammation and oxidative stress in RA. LINC00638 is the differential lncRNA obtained by the research group's previous high-throughput sequencing of the whole transcriptome of peripheral blood PBMCs in RA patients and validation of clinical samples. In order to deepen the molecular biology research of this gene, the microRNA and mRNA targeted by LINC00638 can be further studied from the perspective of competing endogenous RNAs.

Impact of synovial biopsy procedures and disease-specific aspects on synovial tissue outcome: a systematic literature review informing the EULAR points to consider for the minimal reporting requirements in synovial tissue research in rheumatology

BACKGROUND

The aim of this work was to summarise the literature evaluating the impact of biopsy procedures, tissue handling, tissue quality and disease-specific aspects including joint biopsied and disease stage, on synovial tissue outcome.

METHODS

Two reviewers independently identified eligible studies according to the Patients, Intervention, Comparator and Outcome framework obtained for five research questions formulated during the first EULAR task force meeting to produce points to consider (PtC) for minimal reporting requirements in synovial tissue studies. The databases explored were Medline, Embase, CENTRAL and Cinhal. The risk of bias of each study was evaluated using an adapted version of the Joanna Briggs Institute checklist for analytical cross-sectional studies.

RESULTS

Of the 7654 records yielded, 75 full texts were assessed, leading to the inclusion of 26 manuscripts in the systematic literature review (SLR). Two papers assessed the impact of biopsy procedures on the quality and quantity of tissue retrieved alongside patient tolerability; six papers focused on synovial tissue variability. Four papers studied the impact of sample handling or randomisation and 14 assessed the impact of disease stage and state, namely early or established active rheumatoid arthritis and remission on histopathological and transcriptomic results.

CONCLUSIONS

This SLR informs the EULAR PtC for minimal reporting requirements in synovial tissue research in rheumatology. Characteristics related to the study design, population, sample handling, randomisation and analysis can affect the final synovial tissue outcome in the studies reviewed. Thus, accurate reporting of these factors is required in order to ensure the scientific validity of manuscripts describing synovial tissue outcomes.

proBDNF/p75NTR promotes rheumatoid arthritis and inflammatory response by activating proinflammatory cytokines

P75 pan-neurotrophin receptor (p75NTR) is an important receptor for the role of neurotrophins in survival and death of neurons during development and after nerve injury. Our previous research found that the precursor of brain-derived neurotrophic factor (proBDNF) regulates pain as an inflammatory mediator. The current understanding of the role of proBDNF/p75NTR signaling pathway in inflammatory arthritis pain and rheumatoid arthritis (RA) is unclear. We recruited 20 RA patients, 20 healthy donors (HDs), and 10 osteoarthritis (OA) patients. Hematoxylin and eosin (H&E) staining and immunohistochemistry (IHC) of proBDNF and p75NTR in synovial membrane were performed and evaluated. We next examined the mRNA and protein expression of proBDNF/p75NTR signaling pathway in peripheral blood mononuclear cells (PBMCs) and synovial tissue. ELISA and flow cytometry were assessed between the blood of RA patients and HD. To induce RA, collagen-induced arthritis (CIA) were induced in mice. We found over-synovitis of RA synovial membrane compared to OA controls in histologic sections. P75NTR and sortilin mRNA, and proBDNF protein level were significantly increased in PBMCs of RA patients compared with the HD. Consistently, ELISA showed that p75NTR, sortilin, tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and interleukin-10 (IL-10) levels in the serum of RA patients were increased compared with HD and p75NTR, sortilin were positively correlated with Disease Activity Score in 28 joints (DAS28). In addition, using flow cytometry we showed that the increased levels of proBDNF and p75NTR characterized in CD4⁺ and CD8⁺ T cells of RA patients were subsequently reversed with methotrexate (MTX) treatment. Furthermore, we found pathological changes, inflammatory pain, upregulation of the mRNA and protein expression of proBDNF/p75NTR signaling pathway, and upregulation of inflammatory cytokines in spinal cord using a well-established CIA mouse model. We showed intravenous treatment of recombinant p75ECD-Fc that biologically blocked all inflammatory responses and relieved inflammatory pain of animals with CIA. Our findings showed the involvement of proBDNF/p75NTR pathway in the RA inflammatory response and how blocking it with p75ECD-Fc may be a promising therapeutic treatment for RA.

Common Transcriptomic Effects of Abatacept and Other DMARDs on Rheumatoid Arthritis Synovial Tissue

Objectives

Our goal was to assess for the histological and transcriptomic effects of abatacept on RA synovia, and to compare them with previously published data from four other DMARDs: tocilizumab, rituximab, methotrexate, and adalimumab.

Methods

Synovial tissue was obtained using ultrasound-guided biopsy from affected joints of 14 patients, before and 16 weeks after treatment with subcutaneous abatacept 125 mg weekly. Paraffin-sections were stained and scored for CD3⁺, CD20⁺, and CD68⁺ cell infiltration. Transcriptional profiling was performed using GeneChip Human Genome U133 Plus 2.0 arrays (Affymetrix) and analyzed on Genespring GX (Agilent). Pathway analyses were performed on Genespring GX, Metascape, and EnrichR.

Results

Gene expression analysis identified 304 transcripts modulated by abatacept in synovial tissue. Downregulated genes were significantly enriched for immune processes, strongly overlapping with our findings on other therapies. Data were pooled across these studies, revealing that genes downregulated by DMARDs are significantly enriched for both T-cell and myeloid leukocyte activation pathways. Interestingly, DMARDs seem to have coordinate effects on the two pathways, with a stronger impact in good responders to therapy as compared to moderate and non-responders.

Conclusion

We provide evidence that the effects of five DMARDs on the RA synovium culminate in the same pathways. This confirms previous studies suggesting the existence of common mediators downstream of DMARDs, independent of their primary targets.