Heterogeneity Of Rheumatoid Arthritis Research Articles

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.

Synovial Tissue Insights into Heterogeneity of Rheumatoid Arthritis.

Rheumatoid arthritis is one of the most common rheumatic and autoimmune diseases. While it can affect many different organ systems, RA primarily involves inflammation in the synovium, the tissue that lines joints. Patients with RA exhibit significant clinical heterogeneity in terms of presence or absence of autoantibodies, degree of permanent deformities, and most importantly, treatment response. These clinical characteristics point to heterogeneity in the cellular and molecular pathogenesis of RA, an area that several recent studies have begun to address. Single-cell RNA-sequencing initiatives and deeper focused studies have revealed several RA-associated cell populations in synovial tissues, including peripheral helper T cells, autoimmunity-associated B cells (ABCs), and NOTCH3+ sublining fibroblasts. Recent large transcriptional studies and translational clinical trials present frameworks to capture cellular and molecular heterogeneity in RA synovium. Technological developments, such as spatial transcriptomics and machine learning, promise to further elucidate the different types of RA synovitis and the biological mechanisms that characterize them, key elements of precision medicine to optimize patient care and outcomes in RA. This review recaps the findings of those recent studies and puts our current knowledge and future challenges into scientific and clinical perspective.

Molecular and Cellular Heterogeneity in Rheumatoid Arthritis: Mechanisms and Clinical Implications.

Rheumatoid arthritis is an autoimmune disease that exhibits significant clinical heterogeneity. There are various treatments for rheumatoid arthritis, including disease-modifying anti-rheumatic drugs (DMARDs), glucocorticoids, non-steroidal anti-inflammatory drugs (NSAIDs), and inflammatory cytokine inhibitors (ICI), typically associated with differentiated clinical effects and characteristics. Personalized responsiveness is observed to the standard treatment due to the pathophysiological heterogeneity in rheumatoid arthritis, resulting in an overall poor prognosis. Understanding the role of individual variation in cellular and molecular mechanisms related to rheumatoid arthritis will considerably improve clinical care and patient outcomes. In this review, we discuss the source of pathophysiological heterogeneity derived from genetic, molecular, and cellular heterogeneity and their possible impact on precision medicine and personalized treatment of rheumatoid arthritis. We provide emphasized description of the heterogeneity derived from mast cells, monocyte cell, macrophage fibroblast-like synoviocytes and, interactions within immune cells and with inflammatory cytokines, as well as the potential as a new therapeutic target to develop a novel treatment approach. Finally, we summarize the latest clinical trials of treatment options for rheumatoid arthritis and provide a suggestive framework for implementing preclinical and clinical experimental results into clinical practice.

Metabolically engineered stem cell-derived exosomes to regulate macrophage heterogeneity in rheumatoid arthritis.

Despite the remarkable advances in therapeutics for rheumatoid arthritis (RA), a large number of patients still lack effective countermeasures. Recently, the reprogramming of macrophages to an immunoregulatory phenotype has emerged as a promising therapeutic strategy for RA. Here, we report metabolically engineered exosomes that have been surface-modified for the targeted reprogramming of macrophages. Qualified exosomes were readily harvested from metabolically engineered stem cells by tangential flow filtration at a high yield while maintaining their innate immunomodulatory components. When systemically administered into mice with collagen-induced arthritis, these exosomes effectively accumulated in the inflamed joints, inducing a cascade of anti-inflammatory events via macrophage phenotype regulation. The level of therapeutic efficacy obtained with bare exosomes was achievable with the engineered exosomes of 10 times less dose. On the basis of the boosted nature to reprogram the synovial microenvironment, the engineered exosomes display considerable potential to be developed as a next-generation drug for RA.

New insights into macrophage heterogeneity in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a prototypic autoimmune disease that primarily affects joints. Clinical studies and animal models evidenced that mononuclear phagocytes including monocytes and macrophages are crucial to RA pathogenesis, contributing to inflammation and destruction of cartilage and bone. The last decade of research has tremendously changed our view on the origin of tissue-resident macrophages. In light of the recent publications that reveal important phenotypic and functional heterogeneity among macrophages, it is of paramount importance to identify the synovial macrophage subsets that might amplify the inflammatory response or promote the restoration of tissue homeostasis.In this review, we highlight latest studies applying single-cell RNA sequencing that provide deeper insights in macrophage subsets and their putative functions within both human and mouse synovial joint tissue.

Epigenetic Regulation Mediated by Methylation in the Pathogenesis and Precision Medicine of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a complex disease triggered by the interaction between genetics and the environment, especially through the shared epitope (SE) and cell surface calreticulin (CSC) theory. However, the available evidence shows that genetic diversity and environmental exposure cannot explain all the clinical characteristics and heterogeneity of RA. In contrast, recent studies demonstrate that epigenetics play important roles in the pathogenesis of RA, especially DNA methylation and histone modification. DNA methylation and histone methylation are involved in innate and adaptive immune cell differentiation and migration, proliferation, apoptosis, and mesenchymal characteristics of fibroblast-like synoviocytes (FLS). Epigenetic-mediated regulation of immune-related genes and inflammation pathways explains the dynamic expression network of RA. In this review, we summarize the comprehensive evidence to show that methylation of DNA and histones is significantly involved in the pathogenesis of RA and could be applied as a promising biomarker in the disease progression and drug-response prediction. We also explain the advantages and challenges of the current epigenetics research in RA. In summary, epigenetic modules provide a possible interface through which genetic and environmental risk factors connect to contribute to the susceptibility and pathogenesis of RA. Additionally, epigenetic regulators provide promising drug targets to develop novel therapeutic drugs for RA. Finally, DNA methylation and histone modifications could be important features for providing a better RA subtype identification to accelerate personalized treatment and precision medicine.

A Systems Biology Approach for miRNA-mRNA Expression Patterns Analysis in Rheumatoid Arthritis.

Considering the molecular complexity and heterogeneity of rheumatoid arthritis (RA), the identification of novel molecular contributors involved in RA initiation and progression using systems biology approaches will open up potential therapeutic strategies. The bioinformatics method allows the detection of associated miRNA-mRNA as both therapeutic and prognostic targets for RA. This research used a system biology approach based on a systematic re-analysis of the RA-related microarray datasets in the NCBI Gene Expression Omnibus (GEO) database to find out deregulated miRNAs. We then studied the deregulated miRNA-mRNA using Enrichr and Molecular Signatures Database (MSigDB) to identify novel RA-related markers followed by an overview of miRNA-mRNA interaction networks and RA-related pathways. This research mainly focused on mRNA and miRNA interactions in all tissues and blood/serum associated with RA to obtain a comprehensive knowledge of RA. Recent systems biology approach analyzed seven independent studies and presented important RA-related deregulated miRNAs (miR-145-5p, miR-146a-5p, miR-155-5p, miR-15a-5p, miR-29c-3p, miR- 103a-3p, miR-125a-5p, miR-125b-5p, miR-218); upregulation of miR-125b is shown in the study (GSE71600). While the findings of the Enrichr showed cytokine and vitamin D receptor pathways and inflammatory pathways. Further analysis revealed a negative correlation between the vitamin D receptor (VDR) and miR-125b in RA-associated gene expression. Since vitamin D is capable of regulating the immune homeostasis and decreasing the autoimmune process through its receptor (VDR), it is regarded as a potential target for RA. According to the results obtained, a comparative correlation between negative expression of the vitamin D receptor (VDR) and miR-125b was suggested in RA. The increasing miR-125b expression would reduce the VitD uptake through its receptor.

Revealed heterogeneity in rheumatoid arthritis based on multivariate innate signature analysis

A growing body of evidence highlights the persistent activation of the innate immune system and type I interferon (IFN) signature in the pathogenesis of rheumatoid arthritis (RA) and its association with disease activity. Since the recent study revealed heterogeneity in the IFN signature in RA, we investigated for the first time the heterogeneity in innate signature in RA. The innate gene expression signature (10 TLRs, 7 IL1/IL1R family members, and CXCL8/IL8) was assessed in peripheral blood mononuclear cells from RA patients (n=67), both with active (DAS28≥3.2, n=32) and inactive disease (DAS28<3.2, n=35), and in healthy control subjects (n=55). Of the 13 deregulated innate genes (TLR2, TLR3, TLR4, TLR5, TLR8, TLR10, IL1B, IL1RN, IL18, IL18R1, IL1RAP, and SIGIRR/IL1R8) associated with RA, TLR10 and IL1RAP are being reported for the first time. Multivariate analysis based on utilising patient similarity networks revealed the existence of four patient's subsets (clusters) based on different TLR8 and IL1RN expression profiles, two in active and two in inactive RA. Moreover, neural network analysis identified two main gene sets describing active RA within an activity-related innate signature (TLR1, TLR2, TLR3, TLR7, TLR8, CXCL8/IL8, IL1RN, IL18R1). When comparing active and inactive RA, upregulated TLR2, TLR4, TLR6, and TLR8 and downregulated TLR10 (P<0.04) expression was associated with the disease activity. Our study on the comprehensive innate gene profiling together with multivariate analysis revealed a certain heterogeneity in innate signature within RA patients. Whether the heterogeneity of RA elucidated from diversity in innate signatures may impact the disease course and treatment response deserves future investigations.

Synovial Tissue Heterogeneity in Rheumatoid Arthritis and Changes With Biologic and Targeted Synthetic Therapies to Inform Stratified Therapy.

The treatment of rheumatoid arthritis (RA) has been transformed with the introduction of biologic disease modifying anti-rheumatic drugs (bDMARD) and more recently, targeted synthetic DMARD (tsDMARD) therapies in the form of janus-kinase inhibitors. Nevertheless, response to these agents varies such that a trial and error approach is adopted; leading to poor patient quality of life, and long-term outcomes. There is thus an urgent need to identify effective biomarkers to guide treatment selection. A wealth of research has been invested in this field but with minimal progress. Increasingly recognized is the importance of evaluating synovial tissue, the primary site of RA, as opposed to peripheral blood-based investigation. In this mini-review, we summarize the literature supporting synovial tissue heterogeneity, the conceptual basis for stratified therapy. This includes recognition of distinct synovial pathobiological subtypes and associated molecular pathways. We also review synovial tissue studies that have been conducted to evaluate the effect of individual bDMARD and tsDMARD on the cellular and molecular characteristics, with a view to identifying tissue predictors of response. Initial observations are being brought into the clinical trial landscape with stratified biopsy trials to validate toward implementation. Furthermore, development of tissue based omics technology holds still more promise in advancing our understanding of disease processes and guiding future drug selection.

Identification and Validation of Clinically Relevant Clusters of Severe Fatigue in Rheumatoid Arthritis.

The considerable heterogeneity of rheumatoid arthritis (RA)-related fatigue is the greatest challenge to determining pathogenesis. The identification of homogenous subtypes of severe fatigue would inform the design and analysis of experiments seeking to characterize the likely numerous causal pathways that underpin the symptom. This study aimed to identify and validate such fatigue subtypes in patients with RA. Data were obtained from patients recruited to the British Society for Rheumatology Biologics register for RA, as either receiving traditional disease-modifying antirheumatic drugs (DMARD cohort, n = 522) or commencing anti-tumor necrosis factor therapy (anti-TNF cohort, n = 3909). In those reporting severe fatigue (Short-Form 36 vitality ≤ 12.5), this cross-sectional analysis applied hierarchical clustering with weighted-average linkage identified clusters of pain, fatigue, mental health (all Short-Form 36), disability (Health Assessment Questionnaire), and inflammation (erythrocyte sedimentation rate) in the DMARD cohort. K-means clustering sought to validate the solution in the anti-TNF cohort. Clusters were characterized using a priori generated symptom definitions and between-cluster comparisons. Four severe fatigue clusters, labeled as basic (46%), affective (40%), inflammatory (4.5%), and global (8.9%) were identified in the DMARD cohort. All clusters had severe levels of pain and disability and were distinguished by the presence/absence of poor mental health and high inflammation. The same symptom clusters were present in the anti-TNF cohort, although the proportion of participants in each cluster differed (basic = 28.7%; affective = 30.2%; global = 24.1%; inflammatory = 16.9%). Among RA patients with severe fatigue, recruited to two diverse RA cohorts, clinically relevant clusters were identified and validated. These may provide the basis for future mechanistic studies and ultimately support a stratified approach to fatigue management.

A proteomic profile of synoviocyte lesions microdissected from formalin-fixed paraffin-embedded synovial tissues of rheumatoid arthritis.

BackgroundRheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the synovial joints. Early intervention followed by early diagnosis can result in disease remission; however, both early stage diagnosis and provision of effective treatment have been impeded by the heterogeneity of RA, which details of pathological mechanism are unclear. Regardless of numerous investigations of RA by means of genomic and proteomic approaches, proteins interplaying in RA synovial tissues that contain various types of synoviocytes, are not yet sufficiently understood. Hence we have conducted an HPLC/mass spectrometry-based exploratory proteomic analysis focusing on synoviocyte lesions laser-microdissected (LMD) from formalin-fixed paraffin-embedded (FFPE) synovial tissues (RA, n = 15; OA, n = 5), where those of Osteoarthritis (OA) were used as the control.ResultsA total of 508 proteins were identified from the RA and OA groups. With the semi-quantitative comparisons, the spectral index (SpI), log2 protein ratio (RSC) based on spectral counting, and statistical G-test, 98 proteins were found to be significant (pair-wise p < 0.05) to the RA synovial tissues. These include stromelysin-1 (MMP3), proteins S100-A8 and S100-A9, plastin-2, galectin-3, calreticulin, cathepsin Z, HLA-A, HLA-DRB1, ferritin, neutrophil defensin 1, CD14, MMP9 etc.ConclusionsOur results confirmed the involvement of known RA biomarkers such as stromelysin-1 (MMP3) and proteins S100-A8 and S100-A9, and also that of leukocyte antigens such as HLA-DRB1. Network analyses of protein–protein interaction for those proteins significant to RA revealed a dominant participation of ribosome pathway (p = 5.91 × 10−45), and, interestingly, the associations of the p53 signaling (p = 2.34 × 10−5). An involvement of proteins including CD14, S100-A8/S100-A9 seems to suggest an activation of the NF-kB/MAPK signaling pathway. Our strategy of laser-microdissected FFPE-tissue proteomic analysis in Rheumatoid Arthritis thus demonstrated its technical feasibility in profiling proteins expressed in synovial tissues, which may play important roles in the RA pathogenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12014-015-9091-8) contains supplementary material, which is available to authorized users.

THU0069 Ultrasound-Guided Assessement of Axillary Lymph Node Reactivity/Structural Heterogeneity in Rheumatoid Arthritis: Relationship with Disease Activity and Joint Inflammation

BackgroundThere is growing evidence in the murine system suggesting that joint-draining lymph nodes (LN) and the afferent lymphatic system are relevant patho-phisiologic components of chronic arthritis acting through the control...

THU0024 Lack of Association Between IL-15 Genetic Variants and Progression of Joint Destruction in Japanese Rheumatoid Arthritis Patients

BackgroundInterleukin (IL)-15 is a proinflammatory cytokine that is overexpressed in rheumatoid arthritis (RA) patients. Overproduction of IL-15 is generally considered to induce T cell activation and proliferation, possibly contributing to...

Replication of British Rheumatoid Arthritis Susceptibility Loci in Two Unrelated Chinese Population Groups

Previous genome-wide association study by WTCCC identified many susceptibility loci of common autoimmune diseases in British, including rheumatoid arthritis (RA). Because of the genetic heterogeneity of RA, it is necessary to replicate these susceptibility loci in other populations. Here, three SNPs with strong RA association signal in the British were analyzed in Han Chinese, and two SNPs (rs6457617 and rs11761231) were genotyped in the test cohort firstly. The rs6457617 was significantly associated with RA in the test cohort. The individuals bearing the homozygous genotype CC had 0.39-fold risk than these bearing the wild-type genotype TT (P = 0.004, OR 0.39, [95% CI 0.21–0.74]). And the protective effect of allele C was confirmed in another validation cohort with 1514 samples (P genotye CC/TT = 5.9 × 10−10, OR 0.34, [95% CI 0.24–0.48]). The rs6457617 can be used as a tagSNP of HLA-DQA1∗03 which encoded MHC-II α chain. Since MHC restriction is important for primary T-cells in positive selection and negative selection stages, MHC protein polymorphisms may be implicated in shaping the T-cell repertoire, including the emergence of a T-cell clone involved in the inflammatory arthritis.

Evidence for a genetic component to disease severity in RA

Rheumatoid arthritis (RA) is partly heritable; genetic and serological markers are known to confer risk of developing pathology. But given clinical heterogeneity in RA, can we predict who will develop severe disease? Substantial heritability of erosive progression rates has now been identified, but better prognostic biomarkers remain wanting.

Synovial Tissue Heterogeneity and Peripheral Blood Biomarkers

Rheumatoid arthritis is characterized by multiple pathobiological processes and heterogeneous clinical phenotypes. Not surprisingly, the inflamed synovium harbors an equally complex pathology. This includes variability in infiltrating and resident cell populations, spatial arrangements, and cell-cell interactions, as well as gene expression profiles. Remarkable progress in our understanding of the many facets of tissue heterogeneity has been facilitated by the increasing availability of patients' material and the development of advanced research technologies. The next challenge is to capitalize on the large amount of data generated to elucidate the specific pathogenic pathways disparately activated in different patients and/or different phases of the disease. When tissue pathology can be reliably explored through noninvasive circulating biomarkers, then the circle will be closed. We attempt to highlight key advances in the understanding of synovial tissue heterogeneity in rheumatoid arthritis and summarize novel perspectives in synovial biomarker discovery in relation to peripheral blood.

B cell distribution and activation-induced cytidine deaminase expression in rheumatoid synovitis: clinical and bio-molecular correlates

Background and objectivesDevelopment of functional B cell niches in peripheral tissues has been associated to chronicity and pathologic severity in different human conditions such as kidney allograft rejection and multiple...

Synovial tissue heterogeneity in rheumatoid arthritis in relation to disease activity and biomarkers in peripheral blood

To investigate the clinical relevance of synovial tissue subtypes in rheumatoid arthritis (RA) and to search for peripheral blood (PB) markers that may serve as biomarkers for tissue subtypes. Gene expression analysis using complementary DNA microarrays was applied on paired synovial tissue biopsy and PB samples obtained from 17 RA patients. Molecular tissue subtypes were correlated with histologic parameters (CD3, CD22, CD38, CD68, CD163, tumor necrosis factor alpha, intercellular adhesion molecule 1, vascular cell adhesion molecule, and E-selectin), disease characteristics, and PB markers. PANTHER classification was used for pathway analysis. Genomic subtyping of high- and low-inflammation rheumatoid synovial tissues based on gene expression profiles exactly matched immunohistochemical classification. The patients with the high-inflammation tissue type had higher Disease Activity Scores in 28 joints, higher C-reactive protein levels, higher erythrocyte sedimentation rates, increased numbers of platelets, and shorter disease durations. Comparative analysis of PB gene expression profiles yielded no statistically significant differences between the 2 tissue groups at the single-gene expression level. PANTHER pathway analysis revealed a significant association of increased protein biosynthesis with high-inflammation tissue. High-inflammation tissue is associated with more severe disease and shorter disease duration. While pathway-level analysis revealed that coordinate differential expression of genes involved in protein synthesis in PB is associated with high-inflammation tissue types, differential tissue pathology was not reflected in the PB by differential expression of single genes.

The Axis of Thrombospondin-1, Transforming Growth Factor Beta and Connective Tissue Growth Factor: An Emerging Therapeutic Target in Rheumatoid Arthritis

Biologic therapy for rheumatoid arthritis (RA) targets specific molecules that mediate and sustain the clinical manifestations of this complex illness. Compared with the general population, patients with RA die prematurely, in part due to associated cardiovascular disease. Even though the mechanisms by which premature atherosclerosis develops in RA is unknown, chronic inflammation may play a major role. This review connects current knowledge of the pathophysiology of RA with data available in the literature related to thrombospondin-1 (TSP1), transforming growth factor beta (TGFbeta and connective tissue growth factor (CTGF) and their relationship with cardiovascular disease in RA. The TSP1/TGFbeta/CTGF axis may contribute in the pro-inflammatory and pro-atherogenic state in patients affected with RA. In fact, increased TSP1 plasma levels are found in patients of RA. TGFbeta is activated by TSP1 through a non-enzymatic mechanism and is constitutively overexpressed by synovial fibroblasts from RA patients. Activation of TGFbeta pathway in synovial fibroblasts and other cells including neutrophils leads to downstream upregulation of CTGF. Overexpression of CTGF is associated with angiogenesis, fibrosis, atherosclerotic blood vessels and erosive arthritis lesions. Recent RA therapies emphasize the need for aggressive control of the activity of the disease to prevent premature atherosclerosis in RA patients. The complexity and heterogeneity of RA as judged by response to a wide spectrum of treatments mandates the elucidation of unknown pro-inflammatory pathways playing a major role in this disease. The TSP1/TGFbeta/CTFG axis represents one of these pro-inflammatory pathways that may result in the development of promising therapeutic strategies to prevent chronic inflammation and thus premature atherosclerosis in RA.

Genetic heterogeneity in rheumatoid arthritis mouse models induced by extrinsic and intrinsic factors

A cumulative effect of the susceptibility genes with polymorphic alleles may be responsible for rheumatoid arthritis (RA). The objective of this study was to clarify whether susceptibility to RA is under the control of common allelic loci between two different RA models induced by extrinsic and intrinsic factors, collagen-induced arthritis (CIA) in DBA/1 mice and arthritis in MRL/Mp (MRL) mice associated with the Fas deficient mutant gene, Fas(lpr), respectively. CIA was examined in mice of parental DBA/1 and MRL, (MRL x DBA/1) F1 and (MRL x DBA/1) F2 progenies. In genome-wide screening of the severity in the F2 using microsatellite markers, significant linkage was observed on chromosomes 5 and 17 at map position of D5Mit259 and H-2, respectively, associated with DBA/1 alleles, while there was no loci associated with arthritis of MRL-Fas(lpr) mice previously identified. In a quantitative trait locus (QTL) analysis, the locus on chromosome 5 showed the highest peak at map position 35 cM (LOD score 6.0). This study may indicate that the arthritis induced by extrinsic and intrinsic factors is under the control of a different combination of susceptibility genes with common and different alleles, possibly simulating the genetic heterogeneity of RA.