Why location matters - site-specific factors in rheumatic diseases

Joint-level responses to tofacitinib and methotrexate: a post hoc analysis of data from ORAL Start

BACKGROUND

Rheumatoid arthritis (RA) has a variable impact on different synovial joints, with inflammation being more commonly observed in some joints than others. Emerging evidence suggests that the anatomical variation in pathophysiology could result in differential responses to treatments across the joints, both within and between modes of action. This analysis aimed to characterize joint-specific responses to tofacitinib and methotrexate monotherapy in patients with RA.

METHODS

This was a post hoc analysis of data from the phase III trial ORAL Start (NCT01039688), in methotrexate-naïve patients with RA. A paired joint pathology score (PJPS), derived from bilateral tender/swollen joint counts, was calculated. The percentage change from baseline in PJPS (%∆PJPS) and treatment-specific responses (tofacitinib 5 and 10 mg twice daily [BID] vs methotrexate; tofacitinib 5 vs 10 mg BID) for each patient joint pair, except for those with baseline/post-baseline PJPS = 0, were calculated at month 3, month 6, and month 12. Radiographic progression was similarly assessed using the Modified Total Sharp Score at month 6 and month 12.

RESULTS

In methotrexate-naïve patients, differences in %∆PJPS demonstrated greater responses with tofacitinib vs methotrexate in most joint locations. Lesser responses with tofacitinib vs methotrexate were observed in most joints of the feet, particularly at month 12. Despite this, radiographic progression at month 12 was significantly worse in the foot (and metacarpophalangeal) joints of patients receiving methotrexate vs tofacitinib.

CONCLUSION

We observed variation in joint-specific responses with tofacitinib and methotrexate monotherapy. Despite a proximal-distal efficacy gradient, with better clinical responses in the feet, patients receiving methotrexate monotherapy demonstrated more radiographic progression in the foot joints compared with those receiving tofacitinib. These findings suggest that body site- and therapy-specific characteristics may interact to produce differential treatment responses.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01039688.

Site of invasion revisited: epigenetic drivers of joint destruction in RA

New analytical methods and the increasing availability of synovial biopsies have recently provided unprecedented insights into synovial activation in general and synovial fibroblast (SF) biology in particular. In the course of this development, SFs have become one of the most rapidly evolving and exciting fields of rheumatoid arthritis (RA) research. While their active role in the invasion of RA synovium into cartilage has long been studied, recent studies have brought new aspects of their heterogeneity and propagation in RA. This review integrates old and new evidence to give an overview picture of the processes active at the sites of invasive synovial tissue growth in RA.

Early Detection of First Carpometacarpal Joint Osteoarthritis Using Magnetic Resonance Imaging Assessment in Women With High Hypermobility Scores

OBJECTIVE

The aim of this study was to explore association between hypermobility and osteoarthritis (OA) at the first carpometacarpal (CMC) joint, using magnetic resonance imaging (MRI) to identify early change in women at high risk of developing OA but without yet established diagnoses.

METHODS

For this observational study, 33 women (aged 30-50 years) with self-reported history of maternal hand OA but without personal diagnoses of OA were recruited. Participants completed a 5-point hypermobility questionnaire. The 20 participants with 2 or more positive responses were categorized with "high hypermobility scores." The remaining 13 were categorized with "low hypermobility scores." Data collection included functional index, hand pain measure, parity, smoking status, and body mass index. Each participant underwent dominant hand radiographic and MRI examination. Imaging studies were interpreted by assessors blinded to hypermobility score categorization.

RESULTS

No significant differences in age, body mass index, parity, functional index, or pain scores were observed between higher and lower hypermobility score groups. Similarly, there were no significant differences between groups for radiographic changes. However, significantly higher proportions of women with higher hypermobility scores were observed on MRI to have abnormalities of trapezium cartilage (75% vs. 38%), metacarpal cartilage (80% vs. 38%), and trapezium bone (70% vs. 31%); p < 0.05 for all.

CONCLUSIONS

First CMC joint structural abnormalities were more frequently observed in women with higher hypermobility scores. Identification of early preradiographic changes in this group supports the concept that early-life joint laxity may contribute to future OA predisposition. Magnetic resonance imaging may be a preferred imaging test for detection of early cartilage changes in people at high risk of CMC joint OA.

Inflammatory Foot Involvement in Spondyloarthritis: From Tarsitis to Ankylosing Tarsitis

Spondyloarthritis (SpA) is a group that includes a wide spectrum of clinically similar diseases manifested by oligoarticular arthritis and axial or peripheral ankylosis. Although axial SpA is predominant in Caucasians and adult-onset patients, juvenile-onset and Latin American patients are characterized by severe peripheral arthritis and particularly foot involvement. The peripheral involvement of SpA can vary from tarsal arthritis to the most severe form named ankylosing tarsitis (AT). Although the cause and etiopathogenesis of axSpA are often studied, the specific characteristics of pSpA are unknown. Several animal models of SpA develop initial tarsitis and foot ankylosis as the main signs, emphasizing the role of foot inflammation in the overall SpA spectrum. In this review, we attempt to highlight the clinical characteristics of foot involvement in SpA and update the knowledge regarding its pathogenesis, focusing on animal models and the role of mechanical forces in inflammation.

Joint inflammation tends to recur in the same joints during the rheumatoid arthritis disease course

OBJECTIVES

We investigated whether local joint swelling recurs in the same joints over time in patients with rheumatoid arthritis (RA) who are treated to target.

METHODS

Patients with newly diagnosed RA participating in the Behandel-Strategieën, "treatment strategies" (BeSt) study (n=508) were followed for median 10 years while receiving Disease Activity Score (DAS) ≤2.4 steered treatment. Every 3 months 68 joints were assessed for the presence of swelling. We evaluated whether baseline local joint swelling was predictive for swelling in the same joint during follow-up using a multilevel mixed-effect logistic regression model. Different strategies were used to account for missing data. A permutation test was performed to assess if joint swelling was better predicted by baseline swelling of the joint itself than by baseline swelling of randomly selected other joints.

RESULTS

In 46% of the joints that were swollen at baseline, joint swelling later recurred at least once during follow-up. Joint swelling at baseline was statistically significantly associated with swelling in the same joint during follow-up (OR 2.37, 95% CI 2.30 to 2.43, p<0.001), and also specifically with recurrent swelling in the same joint (OR 1.73, 95% CI 1.37 to 1.59, p<0.001). Local joint swelling was better predicted by baseline swelling of that particular joint than by baseline swelling of other joints (p<0.001).

CONCLUSION

Joint swelling tends to recur locally in the joints swollen at RA onset. This suggests that local factors influence the manifestation of joint inflammation over time.

Individual functions of the histone acetyl transferases CBP and p300 in regulating the inflammatory response of synovial fibroblasts

Chromatin remodeling, and a persistent histone 3 lysine 27 acetylation (H3K27ac) in particular, are associated with a sustained inflammatory response of synovial fibroblasts (SF) in rheumatoid arthritis (RA). Here we investigated individual functions of the writers of H3K27ac marks, the homologues histone acetyl transferases (HAT) CBP and p300, in controlling the constitutive and inflammatory gene expression in RA SF. We applied a silencing strategy, followed by RNA-sequencing and pathway analysis, complemented with the treatment of SF with inhibitors targeting the HAT (C646) or bromo domains (I-CBP) of CBP and p300. We showed that CBP and p300 undertook overlapping and, in particular at gene levels, distinct regulatory functions in SF. p300 is the major HAT for H3K27ac in SF and regulated more diverse pathways than CBP. Whereas both factors regulated genes associated with extracellular matrix remodeling, adhesion and proliferation, p300 specifically controlled developmental genes associated with limb development. Silencing of CBP specifically down regulated the TNF-induced expression of interferon-signature genes. In contrast, silencing of p300 resulted in anti- and pro-inflammatory effects. Integration of data sets derived from RNA-sequencing and chromatin immunoprecipitation sequencing for H3K27ac revealed that changes in gene expression after CBP or p300 silencing could be only partially explained by changes in levels of H3K27ac. Inhibition of CBP/p300 using HAT and bromo domain inhibitors strongly mirrored effects obtained by silencing of p300, including anti- and pro-inflammatory effects, indicating that such inhibitors are not sufficient to be used as anti-inflammatory drugs.

Fibroblast pathology in inflammatory joint disease

Rheumatoid arthritis is an immune-mediated inflammatory disease in which fibroblasts contribute to both joint damage and inflammation. Fibroblasts are a major cell constituent of the lining of the joint cavity called the synovial membrane. Under resting conditions, fibroblasts have an important role in maintaining joint homeostasis, producing extracellular matrix and joint lubricants. In contrast, during joint inflammation, fibroblasts contribute to disease pathology by producing pathogenic levels of inflammatory mediators that drive the recruitment and retention of inflammatory cells within the joint. Recent advances in single-cell profiling techniques have transformed our ability to examine fibroblast biology, leading to the identification of specific fibroblast subsets, defining a previously underappreciated heterogeneity of disease-associated fibroblast populations. These studies are challenging the previously held dogma that fibroblasts are homogeneous and are providing unique insights into their role in inflammatory joint pathology. In this review, we discuss the recent advances in our understanding of how fibroblast heterogeneity contributes to joint pathology in rheumatoid arthritis. Finally, we address how these insights could lead to the development of novel therapies that directly target selective populations of fibroblasts in the future.

Capsaicin-Sensitive Peptidergic Sensory Nerves Are Anti-Inflammatory Gatekeepers in the Hyperacute Phase of a Mouse Rheumatoid Arthritis Model

Capsaicin-sensitive peptidergic sensory nerves play complex, mainly protective regulatory roles in the inflammatory cascade of the joints via neuropeptide mediators, but the mechanisms of the hyperacute arthritis phase has not been investigated. Therefore, we studied the involvement of these afferents in the early, "black box" period of a rheumatoid arthritis (RA) mouse model. Capsaicin-sensitive fibres were defunctionalized by pretreatment with the ultrapotent capsaicin analog resiniferatoxin and arthritis was induced by K/BxN arthritogenic serum. Disease severity was assessed by clinical scoring, reactive oxygen species (ROS) burst by chemiluminescent, vascular permeability by fluorescent in vivo imaging. Contrast-enhanced magnetic resonance imaging was used to correlate the functional and morphological changes. After sensory desensitization, both early phase ROS-burst and vascular leakage were significantly enhanced, which was later followed by the increased clinical severity scores. Furthermore, the early vascular leakage and ROS-burst were found to be good predictors of later arthritis severity. We conclude that the anti-inflammatory role of peptidergic afferents depends on their activity in the hyperacute phase, characterized by decreased cellular and vascular inflammatory components presumably via anti-inflammatory neuropeptide release. Therefore, these fibres might serve as important gatekeepers in RA.

Broad proteomic screen reveals shared serum proteomic signature in patients with psoriatic arthritis and psoriasis without arthritis

OBJECTIVE

To identify novel serum proteins involved in the pathogenesis of PsA as compared with healthy controls, psoriasis (Pso) and AS, and to explore which proteins best correlated to major clinical features of the disease.

METHODS

A high-throughput serum biomarker platform (Olink) was used to assess the level of 951 unique proteins in serum of patients with PsA (n = 20), Pso (n = 18) and AS (n = 19), as well as healthy controls (HC, n = 20). Pso and PsA were matched for Psoriasis Area and Severity Index (PASI) and other clinical parameters.

RESULTS

We found 68 differentially expressed proteins (DEPs) in PsA as compared with HC. Of those DEPs, 48 proteins (71%) were also dysregulated in Pso and/or AS. Strikingly, there were no DEPs when comparing PsA with Pso directly. On the contrary, hierarchical cluster analysis and multidimensional scaling revealed that HC clustered distinctly from all patients, and that PsA and Pso grouped together. The number of swollen joints had the strongest positive correlation to ICAM-1 (r = 0.81, P < 0.001) and CCL18 (0.76, P < 0.001). PASI score was best correlated to PI3 (r = 0.54, P < 0.001) and IL-17 receptor A (r = -0.51, P < 0.01). There were more proteins correlated to PASI score when analysing Pso and PsA patients separately, as compared with analysing Pso and PsA patients pooled together.

CONCLUSION

PsA and Pso patients share a serum proteomic signature, which supports the concept of a single psoriatic spectrum of disease. Future studies should target skin and synovial tissues to uncover differences in local factors driving arthritis development in Pso.

A developmental basis for the anatomical diversity of dermis in homeostasis and wound repair

The dermis has disparate embryonic origins; abdominal dermis develops from lateral plate mesoderm, dorsal dermis from paraxial mesoderm and facial dermis from neural crest. However, the cell and molecular differences and their functional implications have not been described. We hypothesise that the embryonic origin of the dermis underpins regional characteristics of skin, including its response to wounding. We have compared abdomen, back and cheek, three anatomical sites representing the distinct embryonic tissues from which the dermis can arise, during homeostasis and wound repair using RNA sequencing, histology and fibroblast cultures. Our transcriptional analyses demonstrate differences between body sites that reflect their diverse origins. Moreover, we report histological and transcriptional variations during a wound response, including site differences in ECM composition, cell migration and proliferation, and re‐enactment of distinct developmental programmes. These findings reveal profound regional variation in the mechanisms of tissue repair. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

MicroRNA-15a/16/SOX5 axis promotes migration, invasion and inflammatory response in rheumatoid arthritis fibroblast-like synoviocytes

Fibroblast-like synoviocytes (FLSs) are key effector cells in the pathogenesis of rheumatoid arthritis (RA) and display a unique aggressive tumor-like phenotype with remarkable hyperplasia, increased cell migration and invasion. How FLSs undergo these changes in RA remains unknown. We previously reported a novel function of transcription factor SOX5 in RA-FLSs that promote cell migration and invasion. In this study, we found that miR-15a/16 directly targets the SOX5 3’UTR and suppresses SOX5 expression. Moreover, miR-15a/16 is significantly down-regulated in RA-FLSs, which negatively correlates with SOX5 expression. Transfection with miR-15a/16 mimics in RA-FLSs inhibits cell migration, invasion, IL-1β and TNFα expression. Overexpression SOX5 in RA-FLSs decreases miR-15a/16 expression and rescues miR-15a/16-mediated inhibitory effect. Furthermore, RA patients with the lower baseline serum miR-15a/16 level present poor response of 3 months disease-modifying antirheumatic drugs (DMARDs) therapy. Collectively, this study reveals that miR-15a/16/SOX5 axis functions as a key driver of RA-FLSs invasion, migration and inflammatory response in a mutual negative feedback loop and correlates with DMARDs treatment response in RA.

Context-dependent HOX transcription factor function in health and disease

During animal development, HOX transcription factors determine the fate of developing tissues to generate diverse organs and appendages. The power of these proteins is striking: mis-expressing a HOX protein causes homeotic transformation of one body part into another. During development, HOX proteins interpret their cellular context through protein interactions, alternative splicing, and post-translational modifications to regulate cell proliferation, cell death, cell migration, cell differentiation, and angiogenesis. Although mutation and/or mis-expression of HOX proteins during development can be lethal, changes in HOX proteins that do not pattern vital organs can result in survivable malformations. In adults, mutation and/or mis-expression of HOX proteins disrupts their gene regulatory networks, deregulating cell behaviors and leading to arthritis and cancer. On the molecular level, HOX proteins are composed of DNA binding homeodomain, and large regions of unstructured, or intrinsically disordered, protein sequence. The primary roles of HOX proteins in arthritis and cancer suggest that mutations associated with these diseases in both the structured and disordered regions of HOX proteins can have substantial functional effects. These insights lead to new questions critical for understanding and manipulating HOX function in physiological and pathological conditions.

Comparison of remission and low disease activity states with DAPSA, MDA and VLDA in a clinical trial setting in psoriatic arthritis patients: 2-year results from the FUTURE 2 study

OBJECTIVES

Remission (REM) or low disease activity (LDA) states were compared in a clinical trial setting of the FUTURE 2 study (NCT01752634) using Disease Activity Index for Psoriatic Arthritis (DAPSA) and Minimal Disease Activity (MDA) composite indices in secukinumab treated PsA patients.

METHODS

The proportion of patients reaching DAPSA-REM (cut-off ≤4) or REM+LDA (≤14), and very low disease activity (VLDA; achieving 7/7 criteria) or MDA (≥5/7), were compared in the overall population, by prior use of anti-TNF therapy, and by time since diagnosis using as observed data. The proportion of patients who met individual core component and other variables of interest were also computed to assess residual disease activity in DAPSA-REM/REM+LDA states and VLDA/MDA responses. The relationship between DAPSA/MDA and patient reported outcomes (PROs), including health-related quality of life, physical function, and fatigue were assessed using mixed model for repeated measures.

RESULTS

More patients could achieve DAPSA-REM or DAPSA-REM+LDA status than VLDA or MDA responses, respectively, at all the time points in the overall population, irrespective of anti‒TNF status and time since diagnosis. Higher proportion of patients reaching DAPSA-REM or VLDA achieved more thresholds of core components (joints, pain, patient and physician global assessments, and function) than DAPSA-REM+LDA or MDA over Week 104. There were differences with numerically higher proportion of patients achieving patient global assessment ≤10 mm and ≤20 mm, and physician global assessment ≤10 mm with MDA than with DAPSA-REM+LDA, and patient pain VAS ≤15 mm, PASI ≤1, HAQ ≤0.5 with VLDA or MDA than with DAPSA-REM or DAPSA-REM+LDA, respectively, through 104 weeks. Improvements in PROs were significantly better for patients in DAPSA-REM+LDA versus DAPSA-moderate+high disease activity status, and for MDA responders versus non-responders.

CONCLUSION

These analysis add to the evidence that both DAPSA and MDA composite index measures can be used for evaluation of the status and treatment response utilizing a treat to target approach in PsA patients in a clinical trial setting and improve patient health related outcomes.

FUNDING

The study and analysis was funded by Novartis Pharma AG, Basel, Switzerland.

The relation between physical joint examination and MRI-depicted inflammation of metatarsophalangeal joints in early arthritis

BACKGROUND

The relationship between physical joint examination (PE) and MRI-detected inflammation in early inflammatory arthritis has mostly been studied in the hands. Physical examination of MTP joints is considered difficult, and for these joints, this relationship is unknown. Therefore, we studied the concordance of PE with MRI inflammation in MTP joints. Metacarpophalangeal (MCP) joints were included for comparison.

METHODS

One thousand seven hundred fifty-nine MTP(2-5) and 1750 MCP(2-5) joints of 441 consecutive patients with early arthritis underwent PE (for joint swelling) and MRI, all evaluated by two assessors. MRI was scored for synovitis, tenosynovitis, and osteitis (summed MRI inflammation). Synovial intermetatarsal bursae may enlarge upon inflammation and become palpable and were therefore also assessed. Analyses (frequencies, GEE) were performed on joint level.

RESULTS

PE and MRI were concordant in 79% of MTP joints. Of 1606 non-swollen MTP joints, 83% showed no MRI inflammation and 17% showed subclinical MRI inflammation. Of 153 swollen MTP joints, 48% had MRI inflammation and 52% (79 MTP joints) did not. Of these 79 swollen MTP joints without MRI inflammation, 31 showed intermetatarsal bursitis and 48 joints had none of these MRI abnormalities (this concerned 31% of swollen MTP joints). MTP swelling was statistically independently associated with tenosynovitis (OR 2.21, 95% CI 1.1-4.3) and intermetatarsal bursitis (OR 2.91, 95% CI 1.8-4.8). MTP joints showed subclinical inflammation less often than MCP joints (17% vs. 34%, P < 0.001). Swollen MTP joints showed MRI inflammation less often than swollen MCP joints (48% vs. 88%, P < 0.001).

CONCLUSIONS

The absence of swelling of MTP joints in early arthritis is mostly accompanied by the absence of MRI-detected inflammation. Swollen MTP joints are, in addition to synovitis, also explained by tenosynovitis and intermetatarsal bursitis and partly unexplained by MRI. Their clinical relevance must be determined in longitudinal studies.

Subsequent Cardiovascular Events Among Patients With Rheumatoid Arthritis, Psoriatic Arthritis, or Psoriasis: Patterns of Disease-Modifying Antirheumatic Drug Treatment

Objective

To examine disease‐modifying antirheumatic drug (DMARD) treatments and estimate the risk of a subsequent cardiovascular (CV) event following an initial CV event in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), or psoriasis.

Methods

We analyzed data from MarketScan claims databases (January 1, 2006 to June 30, 2015) for adults with RA, PsA, or psoriasis and an initial/index CV event (acute myocardial infarction, stroke, or coronary revascularization) while receiving DMARDs (tumor necrosis factor inhibitor [TNFi] biologic DMARDs [bDMARDs], conventional synthetic DMARDs [csDMARDs], or non‐TNFi bDMARDs). We studied DMARD treatment patterns following the index event and rates of subsequent CV events. We used Cox regression to investigate predictors of DMARD discontinuation and risk factors for subsequent CV events.

Results

Among 10,254 patients, 15.3% discontinued and 15.5% switched DMARD therapy after the index CV event. Independent predictors of DMARD discontinuation included a psoriasis diagnosis, renal disease, hypertension, heart failure, diabetes mellitus, older age, and baseline csDMARD or non‐TNFi bDMARD use (versus TNFi bDMARDs). Rates per 1,000 patient‐years of subsequent events were 75.2 (95% confidence interval [95% CI] 54.4–96.0) for patients taking TNFi bDMARDs, 83.6 (95% CI 53.3–113.9) for csDMARDs, and 122.4 (95% CI 60.6–184.3) for non‐TNFi bDMARDs. A diagnosis of RA (versus psoriasis) and heart failure at baseline, but not a DMARD pattern after the index event, were independently associated with an increased risk of subsequent CV event.

Conclusion

In this large nationwide study, nearly one‐third of patients with RA, PsA, or psoriasis switched or discontinued DMARD therapy following a CV event. There was no association between DMARD class and the risk of a subsequent CV event.

Where to Stand with Stromal Cells and Chronic Synovitis in Rheumatoid Arthritis?

The synovium exercises its main function in joint homeostasis through the secretion of factors (such as lubricin and hyaluronic acid) that are critical for the joint lubrication and function. The main synovium cell components are fibroblast-like synoviocytes, mesenchymal stromal/stem cells and macrophage-like synovial cells. In the synovium, cells of mesenchymal origin modulate local inflammation and fibrosis, and interact with different fibroblast subtypes and with resident macrophages. In pathologic conditions, such as rheumatoid arthritis, fibroblast-like synoviocytes proliferate abnormally, recruit mesenchymal stem cells from subchondral bone marrow, and influence immune cell activity through epigenetic and metabolic adaptations. The resulting synovial hyperplasia leads to secondary cartilage destruction, joint swelling, and pain. In the present review, we summarize recent findings on the molecular signature and the roles of stromal cells during synovial pannus formation and rheumatoid arthritis progression.

Acne: Transient Arrest in the Homeostatic Host-Microbiota Dialog?

We propose that acne vulgaris represents a naturally developing, transient inflammatory interaction of adolescent facial skin with its new microbial/chemical milieu (Cutibacterium acnes, sebum), replacing a state of previous childhood skin homeostasis. This concept might explain why acne is characterized by strong regional and age specificity, prevalent occurrence, and resolution.

The relation between upper extremity joint involvement and grip force in early rheumatoid arthritis: a retrospective study

To investigate the relation between joint involvement in the upper extremities and grip force in patients with early rheumatoid arthritis (RA). An inception cohort of 225 patients with early RA was followed according to a structured protocol. The same rheumatologist assessed all patients for swollen joints and joint tenderness. Grip force was measured (Grippit; AB Detektor, Gothenburg, Sweden) at the same visit. Average grip force values for the dominant hand were expressed as % of expected, based on age- and sex-specific reference values from the literature. Associations between grip force and current synovitis or tenderness of individual joints, and other disease parameters measured at the same visit, were examined. Patients with current synovitis of the wrist joint or ≥ 1 metacarpophalangeal (MCP) joint of the dominant hand had a significantly lower grip force at inclusion, at 1 year and at 5 years. Proximal interphalangeal joint tenderness and MCP joint tenderness were consistently associated with reduced grip force. In multivariate analysis, extensive MCP joint synovitis was associated with lower grip force at inclusion (β - 2.8% per joint; 95% CI - 5.3 to - 0.4), and also at the 1-year follow-up. Patient reported pain scores and erythrocyte sedimentation rates had independent negative associations with grip force at all time points. In patients with early RA, extensive synovitis of the MCP joints was associated with reduced grip force, independently of other upper extremity joint involvement. Pain and inflammation have effects on hand function beyond those mediated by local synovitis.

Pathogenic stromal cells as therapeutic targets in joint inflammation

Knowledge of how the joint functions as an integrated unit in health and disease requires an understanding of the stromal cells populating the joint mesenchyme, including fibroblasts, tissue-resident macrophages and endothelial cells. Knowledge of the physiological and pathological mechanisms that involve joint mesenchymal stromal cells has begun to cast new light on why joint inflammation persists. The shared embryological origins of fibroblasts and endothelial cells might shape the behaviour of these cell types in diseased adult tissues. Cells of mesenchymal origin sustain inflammation in the synovial membrane and tendons by various mechanisms, and the important contribution of newly discovered fibroblast subtypes and their associated crosstalk with endothelial cells, tissue-resident macrophages and leukocytes is beginning to emerge. Knowledge of these mechanisms should help to shape the future therapeutic landscape and emphasizes the requirement for new strategies to address the pathogenic stroma and associated crosstalk between leukocytes and cells of mesenchymal origin.

Anti-Inflammatory and Anti-Arthritic Efficacies of an Indian Traditional Herbo-Mineral Medicine "Divya Amvatari Ras" in Collagen Antibody-Induced Arthritis (CAIA) Mouse Model Through Modulation of IL-6/IL-1β/TNF-α/NFκB Signaling

Rheumatoid arthritis (RA) is defined as a chronic autoimmune inflammatory disorder that causes damage to limb joints and progressive injuries to secondary organs. Medical practitioners prescribe Methotrexate (MTX) as standard care medicine for treating RA. However, the long-term application of MTX has shown to have adverse health-related effects. Divya Amvatari Ras (DAR), an Indian Ayurvedic herbo-mineral formulation, has been described in ancient texts to provide relief from RA inflammation associated distress. Therefore, in the present study, we explored the biocompatibility, anti-inflammatory, and anti-arthritic efficacy of DAR using in vivo and in vitro disease models. Using carrageenan (CA)-stimulated Wistar rat paw edema model, we showed a reduction in inflammation-induced paw edema at human equivalent dose of DAR. Anti-rheumatic efficacy of DAR was studied using collagen-antibody cocktail (C-Ab) Induced Arthritis (CAIA) mouse model. The onset of RA in the CAIA mice was determined using parameters such as the increase in arthritis score, and induction of disease associated lesions in the ankle and knee joints, and increase in mechanical and thermal hyperalgesia. Treatment of CAIA animals with a human equivalent dose of DAR significantly reversed the RA-associated pathogenesis. These effects were comparable with the standard of care RA drug, MTX. DAR acted at multiple levels of inflammation associated with RA to reduce progressive pathogenesis. Animal serum biochemistry showed DAR was capable of ameliorating RA induced increase in liver enzyme Alanine Aminotransferase (ALT) and pro-inflammatory cytokine interleukin 6 (IL-6). In the lipopolysaccharide stimulated THP-1 cells, DAR was found to inhibit the release of IL-6, IL-1β, TNF-α, and upstream inflammatory gene regulatory protein, NFκB. The study endorsed the anti-arthritic and anti-inflammatory activity of the Indian Traditional herbo-mineral medicine, DAR. These results also confirm that DAR was highly biocompatible and would show minimal health-related side effects than those associated with standard of care MTX. Taken together, we show that the DAR could be utilized as a promising alternative or complementary therapy for treating rheumatoid arthritis.

Bromodomain protein inhibition: a novel therapeutic strategy in rheumatic diseases

The reading of acetylation marks on histones by bromodomain (BRD) proteins is a key event in transcriptional activation. Small molecule inhibitors targeting bromodomain and extra-terminal (BET) proteins compete for binding to acetylated histones. They have strong anti-inflammatory properties and exhibit encouraging effects in different cell types in vitro and in animal models resembling rheumatic diseases in vivo. Furthermore, recent studies that focus on BRD proteins beyond BET family members are discussed.

Functional genomics of stromal cells in chronic inflammatory diseases

PURPOSE OF REVIEW

Stroma is a broad term referring to the connective tissue matrix in which other cells reside. It is composed of diverse cell types with functions such as extracellular matrix maintenance, blood and lymph vessel development, and effector cell recruitment. The tissue microenvironment is determined by the molecular characteristics and relative abundances of different stromal cells such as fibroblasts, endothelial cells, pericytes, and mesenchymal precursor cells. Stromal cell heterogeneity is explained by embryonic developmental lineage, stages of differentiation to other cell types, and activation states. Interaction between immune and stromal cell types is critical to wound healing, cancer, and a wide range of inflammatory diseases. Here, we review recent studies of inflammatory diseases that use functional genomics and single-cell technologies to identify and characterize stromal cell types associated with pathogenesis.

RECENT FINDINGS

High dimensional strategies using mRNA sequencing, mass cytometry, and fluorescence activated cell-sorting with fresh primary tissue samples are producing detailed views of what is happening in diseased tissue in rheumatoid arthritis, inflammatory bowel disease, and cancer. Fibroblasts positive for CD90 (Thy-1) are enriched in the synovium of rheumatoid arthritis patients. Single-cell RNA-seq studies will lead to more discoveries about the stroma in the near future.

SUMMARY

Stromal cells form the microenvironment of inflamed and diseased tissues. Functional genomics is producing an increasingly detailed view of subsets of stromal cells with pathogenic functions in rheumatic diseases and cancer. Future genomics studies will discover disease mechanisms by perturbing molecular pathways with chemokines and therapies known to affect patient outcomes. Functional genomics studies with large sample sizes of patient tissues will identify patient subsets with different disease phenotypes or treatment responses.

The Tumor-Like Phenotype of Rheumatoid Synovium: Molecular Profiling and Prospects for Precision Medicine

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by destructive hyperplasia of the synovium. Fibroblast-like synoviocytes (FLS) are a major component of synovial pannus and actively participate in the pathologic progression of RA. How rheumatoid FLS acquire and sustain such a uniquely aggressive phenotype remains poorly understood. We describe the current state of knowledge of the molecular alterations in rheumatoid FLS at the genomic, epigenomic, transcriptomic, proteomic, and metabolomic levels, which offers a means to reconstruct the pathways leading to rheumatoid pannus. Such data provide new pathologic insight and suggest means to more sensitively assess disease activity and response to therapy, as well as support new avenues for therapeutic development.

Evaluation of the joint distribution at disease presentation of patients with rheumatoid arthritis: a large study across continents

Background

Genetic and environmental risk factors for rheumatoid arthritis (RA) are population dependent and may affect disease expression. Therefore, we studied tender and swollen joint involvement in patients newly diagnosed with RA in four countries and performed a subanalysis within countries to assess whether the influence of autoantibody positivity affected disease expression.

Methods

Patients with symptom duration <2 years fulfilling the American College of Rheumatology/European League Against Rheumatism 2010 RA classification criteria were selected from METEOR (Measurement of Efficacy of Treatment in the Era of Outcome in Rheumatology), an international observational database, and the Dutch Leiden Early Arthritis Clinic. Indian (n=947), Mexican (n=141), South African (n=164) and Dutch (n=947) autoantibody-positive and negative patients with RA, matched by symptom duration, were studied for swollen and tender joint distribution.

Results

Between countries, the reported distribution of swollen joint distribution differed, with more knee synovitis in Mexico, South Africa and India compared with the Netherlands (37%, 36%, 30% and 13%) and more elbow (29%, 23%, 7%, 7%) and shoulder synovitis (21%, 11%, 0%, 1%) in Mexico and South Africa compared with India and the Netherlands.

Since the number of autoantibody-negative patients in Mexico and South Africa was limited, Indian and Dutch autoantibody-positive and negative patients with RA were compared. The number of swollen and tender joints was higher in autoantibody-negative patients, but the overall distribution of involved joints was similar.

Conclusion

Joint involvement at diagnosis does not differ between autoantibody-positive and negative patients with RA in India and the Netherlands. However, joint involvement is reported differently across countries. More research is needed whether these differences are cultural and/or pathogenetic.