Serum Angiogenesis Markers and Their Correlation with Ultrasound-Detected Synovitis in Juvenile Idiopathic Arthritis

Where are we in targeting hypoxia-induced pathways in inflammatory arthritis? Current understanding, insights, and future directions

INTRODUCTION

Joint tissues affected by inflammatory arthritis (IA) create hypoxic microenvironments that sustain the inflammatory response. Although targeting molecules in hypoxia-induced pathways has provided valuable insights into potential novel therapies for various types of IA, progress remains preclinical, and no clinical trials have been conducted for IA.

METHODS

A literature search was conducted to create a narrative review exploring the role of hypoxia and its signaling pathways in IA pathogenesis, as well as the potential and future directions for IA therapies that target hypoxia-induced molecules before moving forward to clinical applications.

RESULTS

Hypoxia is a prevalent feature of the IA synovial microenvironment and contributes to disease progression. Various studies and preclinical models demonstrate how hypoxia-inducible factors, vascular endothelial growth factors, and matrix metalloproteinases, among other molecules, influence rheumatoid arthritis, axial spondyloarthritis, psoriatic arthritis, and juvenile idiopathic arthritis. Despite these findings, drug development targeting these molecules in IA has been limited due to challenges in delineating the mechanistic pathways of hypoxia, the distinct roles of hypoxia-induced molecules depending on anatomical sites, and concerns regarding pharmacokinetics and patient safety. However, given that hypoxia-induced molecule-targeting therapies have been successfully approved for treating cancers and cardiovascular diseases, further research is needed to advance the application of similar medications in IA.

CONCLUSIONS

Given the pathogenic effects of hypoxic microenvironments in IA, it is imperative to continue gathering compelling evidence to advance hypoxia-induced therapies. Furthermore, elucidating the safety and efficacy of such drugs in various preclinical models, in collaboration with chemists and the pharmaceutical industry, is crucial for accelerating the development of novel, optimized treatment methods.

Characteristic inflammatory biomarkers in an equine model of persistent synovitis induced by the intra-articular administration of monoiodoacetic acid

Persistent synovitis damages the articular cartilage in horses. To evaluate the effectiveness of treatment for synovitis using a model induced by intra-articular administration of monoiodoacetic acid (MIA), it is necessary to identify inflammatory biomarkers characteristic of the MIA model. Synovitis was induced by administering MIA into the unilateral antebrachiocarpal joints of five horses, and saline was injected into the contralateral joints as a control on day 0. Clinical and ultrasonographic examinations and synovial fluid collection were performed on days 0, 1, 2, 7, 14, 21, 28, and 35. Leukocyte, lactate dehydrogenase (LDH), tumor necrosis factor-α (TNF-α), interleukin-1 receptor antagonist (IL-1Ra), interleukin-6 (IL-6), and transforming growth factor-β1 (TGF-β1) concentrations in the synovial fluid were measured. Synovium was obtained after euthanasia on day 42 and histologically examined before quantification of the gene expression of inflammatory biomarkers by real-time PCR. Acute inflammatory symptoms persisted for approximately two weeks before returning to control levels. However, some indicators of chronic inflammation remained elevated until day 35. On day 42, synovitis continued histologically, with osteoclasts. The expressions of matrix metalloproteinase 13 (MMP13), a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4), receptor activator of nuclear factor kappa-Β ligand (RANKL), and collagen type I α2 chain (Col1a2) were significantly higher in the MIA model than in the control. In the MIA model, representative inflammatory biomarkers in the chronic inflammatory stage were persistently expressed in both synovial fluid and tissue, suggesting that they may be useful for the assessment of the anti-inflammatory effect of drugs.

Study of the shared gene signatures of polyarticular juvenile idiopathic arthritis and autoimmune uveitis

Objective

To explore the shared gene signatures and potential molecular mechanisms of polyarticular juvenile idiopathic arthritis (pJIA) and autoimmune uveitis (AU).

Method

The microarray data of pJIA and AU from the Gene Expression Omnibus (GEO) database were downloaded and analyzed. The GEO2R tool was used to identify the shared differentially expressed genes (DEGs) and genes of extracellular proteins were identified among them. Then, weighted gene co-expression network analysis (WGCNA) was used to identify the shared immune-related genes (IRGs) related to pJIA and AU. Moreover, the shared transcription factors (TFs) and microRNAs (miRNAs) in pJIA and AU were acquired by comparing data from HumanTFDB, hTFtarget, GTRD, HMDD, and miRTarBase. Finally, Metascape and g: Profiler were used to carry out function enrichment analyses of previously identified gene sets.

Results

We found 40 up-regulated and 15 down-regulated shared DEGs via GEO2R. Then 24 shared IRGs in positivity-related modules, and 18 shared IRGs in negatively-related modules were found after WGCNA. After that, 3 shared TFs (ARID1A, SMARCC2, SON) were screened. And the constructed TFs-shared DEGs network indicates a central role of ARID1A. Furthermore, hsa-miR-146 was found important in both diseases. The gene sets enrichment analyses suggested up-regulated shared DEGs, TFs targeted shared DEGs, and IRGs positivity-correlated with both diseases mainly enriched in neutrophil degranulation process, IL-4, IL-13, and cytokine signaling pathways. The IRGs negatively correlated with pJIA and AU mainly influence functions of the natural killer cell, cytotoxicity, and glomerular mesangial cell proliferation. The down-regulated shared DEGs and TFs targeted shared DEGs did not show particular functional enrichment.

Conclusion

Our study fully demonstrated the flexibility and complexity of the immune system disorders involved in pJIA and AU. Neutrophil degranulation may be considered the shared pathogenic mechanism, and the roles of ARID1A and MiR-146a are worthy of further in-depth study. Other than that, the importance of periodic inspection of kidney function is also noteworthy.

Summary Report of the Arthritis Foundation and the American Orthopaedic Foot & Ankle Society's Symposium on Targets for Osteoarthritis Research: Part 1: Epidemiology, Pathophysiology, and Current Imaging Approaches

This first of a 2-part series of articles recounts the key points presented in a collaborative symposium sponsored jointly by the Arthritis Foundation and the American Orthopaedic Foot & Ankle Society with the intent to survey the state of scientific knowledge related to incidence, diagnosis, pathologic mechanisms, and injection treatment options for osteoarthritis (OA) of the foot and ankle. A meeting was held virtually on December 3, 2021. A group of experts were invited to present brief synopses of the current state of knowledge and research in this area. Part 1 overviews areas of epidemiology and pathophysiology, current approaches in imaging, diagnostic and therapeutic injections, and genetics. Opportunities for future research are discussed. The OA scientific community, including funding agencies, academia, industry, and regulatory agencies, must recognize the needs of patients that suffer from arthritis of foot and ankle. The foot and ankle contain a myriad of interrelated joints and tissues that together provide a critical functionality. When this functionality is compromised by OA, significant disability results, yet the foot and ankle are generally understudied by the research community. Level of Evidence: Level V - Review Article/Expert Opinion.

B Cells on the Stage of Inflammation in Juvenile Idiopathic Arthritis: Leading or Supporting Actors in Disease Pathogenesis?

Juvenile idiopathic arthritis (JIA) is a term that collectively refers to a group of chronic childhood arthritides, which together constitute the most common rheumatic condition in children. The International League of Associations for Rheumatology (ILAR) criteria define seven categories of JIA: oligoarticular, polyarticular rheumatoid factor (RF) negative (RF-), polyarticular RF positive (RF+), systemic, enthesitis-related arthritis, psoriatic arthritis, and undifferentiated arthritis. The ILAR classification includes persistent and extended oligoarthritis as subcategories of oligoarticular JIA, but not as distinct categories. JIA is characterized by a chronic inflammatory process affecting the synovia that begins before the age of 16 and persists at least 6 weeks. If not treated, JIA can cause significant disability and loss of quality of life. Treatment of JIA is adjusted according to the severity of the disease as combinations of non-steroidal anti-inflammatory drugs (NSAIDs), synthetic and/ or biological disease modifying anti-rheumatic drugs (DMARDs). Although the disease etiology is unknown, disturbances in innate and adaptive immune responses have been implicated in JIA development. B cells may have important roles in JIA pathogenesis through autoantibody production, antigen presentation, cytokine release and/ or T cell activation. The study of B cells has not been extensively explored in JIA, but evidence from the literature suggests that B cells might have indeed a relevant role in JIA pathophysiology. The detection of autoantibodies such as antinuclear antibodies (ANA), RF and anti-citrullinated protein antibodies (ACPA) in JIA patients supports a breakdown in B cell tolerance. Furthermore, alterations in B cell subpopulations have been documented in peripheral blood and synovial fluid from JIA patients. In fact, altered B cell homeostasis, B cell differentiation and B cell hyperactivity have been described in JIA. Of note, B cell depletion therapy with rituximab has been shown to be an effective and well-tolerated treatment in children with JIA, which further supports B cell intervention in disease development.

Assessment of angiogenesis-related parameters in juvenile idiopathic arthritis-associated uveitis

PURPOSE

Juvenile idiopathic arthritis-associated uveitis (JIAU) may run a chronic and treatment-resistant course, and occasionally, alterations of the iris vasculature may be observed clinically.

METHODS

Iris tissue (IT), aqueous humor (AH) and serum samples from patients with clinically inactive JIAU (n = 30), acute anterior uveitis (AAU; n = 18), and primary open angle glaucoma (POAG; n = 20) were obtained during trabeculectomy or cataract surgery. Samples were analyzed by RNA-Seq, qRT-PCR, LC-IMS, Western-Blot, and LEGENDplex™ analysis. Pattern of iris vasculature in JIAU patients was assessed qualitatively via fluorescein and indocyanine green angiography (FLA/ICGA).

RESULTS

RNA-Seq of IT showed significantly differential expression (DE) of 136 genes between JIAU and POAG, of which 15 were associated with angiogenesis. qRT-PCR, performed to validate RNA-Seq results, showed upregulation of the angiogenesis-related genes Kdr, Angpt-1, Tie-1, Tie-2 and Mmrn2 in IT (JIAU vs POAG, p > 0.05). LC-IMS of IT revealed a total number of 56 DE proteins (JIAU vs POAG), of which Angiopoetin, Lumican and Decorin were associated with angiogenesis and showed increased (p > 0.05) expression on Western-Blot analysis. LEGENDplex™ analysis showed upregulation of ANGPT-2 in AH from JIAU compared to AAU and POAG, whereas VEGF was upregulated in AAU. Iris vascular leakage, hypoperfusion and neovascularization were observed by FLA/ICGA in JIA patients with treatment-refractory complicated course of uveitis.

CONCLUSION

Angiogenesis-related factors could play a role in long-standing complicated JIAU, leading to clinically visible alterations in selected cases.

How Does Endothelial Permeability Affect the Development of Juvenile Idiopathic Arthritis? Vascular Endothelial Cadherin as a Promising New Tool Helpful in the Diagnostic Process

Introduction

Vascular endothelial cadherin (VE-cadherin) is a calcium-dependent protein essential for stabilization of the adherens junctions of the endothelial cells. Through vasculogenic mimicry, VE-cadherin may influence angiogenesis in synovial fibroblast-like cells. The soluble extracellular domain of VE-cadherin may be considered an indicator of endothelial dysfunction. Its potential as a diagnostic biomarker in rheumatic diseases, including juvenile idiopathic arthritis (JIA), needs to be investigated.

Materials and Methods

The study group included 80 patients diagnosed with JIA. In 53 individuals, blood samples were obtained twice with an average interval of 102.4 ± 4.6 days. Results from the study group were compared to 29 age- and sex-matched healthy children.

Results

Serum levels of VE-cadherin were significantly higher in JIA patients than in healthy controls. In such comparison, VE-cadherin had 87.5% sensitivity and 69.0% specificity for the cutoff level 4.36 ng/ml (Youden index 0.56, area under the curve 0.724). VE-cadherin concentrations negatively correlated with the disease activity score. However, such finding may be a false result because of the downregulation of VE-cadherin induced by glucocorticosteroids.

Conclusions

VE-cadherin may become a promising diagnostic biomarker of early stages of JIA. Its predictive significance may be decreased by utilization of glucocorticosteroids. A multicentre study including patients with other arthritides is recommended for further evaluation of this protein.

Role of Interleukin 37 as a Novel Proangiogenic Factor in Juvenile Idiopathic Arthritis

OBJECTIVE

The aim of this study was to investigate interleukin 37 (IL-37) levels in the serum and synovial fluid of patients with juvenile idiopathic arthritis (JIA), its expression in peripheral blood mononuclear cells, and correlation with disease activity and angiogenesis.

METHODS

Seventy JIA patients and 50 control subjects were examined. The Juvenile Arthritis Disease Activity Score in 27 joints (JADAS-27) was calculated. Immunoassays were used to measure the serum and synovial fluid levels of IL-37, vascular endothelial growth factor (VEGF), soluble VEGF receptor 1 (sVEGF-R1), and sVEGF-R2. Relative expression of IL-37 mRNA in peripheral blood mononuclear cells and the power Doppler ultrasound score of the affected joint were measured.

RESULTS

Patients with JIA were subdivided as 20 systemic-onset, 20 polyarticular, and 30 oligoarticular (10 persistent, 20 extended) cases. Serum levels of IL-37, VEGF, VEGF-R1, and VEGF-R2 and relative IL-37 mRNA expression were significantly higher in JIA patients when compared with the control subjects (p < 0.001). These concentrations were significantly higher in systemic-onset JIA compared with those in polyarticular and oligoarticular JIA, and in polyarticular JIA when compared with oligoarticular JIA (p < 0.001). Serum, synovial, and mRNA expression levels of IL-37 were positively correlated with C-reactive protein, erythrocyte sedimentation rate, Juvenile Arthritis Disease Activity Score in 27 joints, power Doppler ultrasound score (p < 0.001), and the serum and synovial VEGF and VEGF-RI and -R2 levels (p < 0.05).

CONCLUSIONS

Our results demonstrate that IL-37 levels and mRNA expression were significantly increased in JIA patients, and their levels were positively correlated with disease activity and markers of angiogenesis (VEGF and VEGF receptors), suggesting that IL-37 may be correlated with angiogenesis.

Association of Angiogenic and Inflammatory Markers with Power Doppler Ultrasound Vascularity Grade and DAS28-CRP in Early Rheumatoid Arthritis: A Comparative Analysis

Objective

Upregulation of various proinflammatory and angiogenic mediators orchestrates the typical pathological synovial alterations in rheumatoid arthritis (RA). DAS28-CRP is commonly used for assessment of RA disease activity and power Doppler ultrasonography (PDUS) is an important modality for assessing synovial vascularity. This study was intended to look for the association of various inflammatory and angiogenic mediators, with respect to different PDUS vascularity grades and disease activity status, in early RA patients.

Methods

50 early RA patients (<6 months disease duration) with either moderate or high disease activity and 30 healthy controls were included in this study. RA patients were subcategorized based on PDUS vascularity grading of wrist joints. Serum levels of proinflammatory cytokines [tumor necrosis factor-α (TNF- α); interleukin-6(IL-6)] and angiogenic markers [angiopoietin-1 and 2 (Ang-1 and Ang-2); vascular endothelial growth factor (VEGF) ] were measured and compared among different patient subgroups.

Results

Among 50 patients, 22 and 28 patients had moderate and high DAS28-CRP score, respectively. Patients with grade 3 PDUS score, even with moderate DAS value, showed a significant rise in Ang-1 (p<0.02), VEGF (p<0.008), Ang-2 (p <0.001), and TNF-α (p<0.005) level compared to grade 2 PDUS patients with high DAS values.

Conclusion

Higher serum level of angiogenic and inflammatory markers was noted among patients with moderate disease activity but with advanced PDUS vascularity (grade 3) in comparison to high disease activity group with less severe PDUS vascularity (grade 2). PDUS vascularity grading better reflects some markers of angiogenesis and inflammation, than composite disease activity index.

A fresh look at angiogenesis in juvenile idiopathic arthritis

Angiogenesis is the complex process of creating new capillaries from preexisting blood vessels due to hypoxemia, injury or inflammation of the tissues. Numerous cytokines and cell mediators have been identified to induce and stimulate angiogenesis, but vascular endothelial growth factor (VEGF) is a key regulator. The role of proangiogenic factors in the pathogenesis of chronic arthritis is currently a subject of intensive investigations in adult patients with rheumatoid arthritis (RA) and, to a limited extent, in children with juvenile idiopathic arthritis (JIA). Recent studies has shown a significant correlation between proangiogenic marker concentrations and the severity of inflammation in either RA or JIA patients. The serum neovascularization markers correlate with the power Doppler ultrasound image of the inflamed joint and hypertrophic synovium, which may be connected with the disease activity.

The aim of this paper is to describe the state of the art on the important role of angiogenesis in adult and childhood rheumatoid arthritis.

Ultrasound in juvenile idiopathic arthritis

BACKGROUND

In the recent years, musculoskeletal ultrasound (MSUS) has been regarded as especially promising in the assessment of juvenile idiopathic arthritis (JIA), as a reliable method to precisely document and monitor the synovial inflammation process.

MAIN CONTENT

MSUS is particularly suited for examination of joints in children due to several advantages over other imaging modalities. Some challenges should be considered for correct interpretation of MSUS findings in children, due to the peculiar features of the growing skeleton. MSUS in JIA is considered particularly useful for its ability to detect subclinical synovitis, to improve the classification of patients in JIA subtypes, for the definition of remission, as guidance to intraarticular corticosteroid injections and for capturing early articular damage. Current evidence and applications of MSUS in JIA are documented by several authors. Recent advances and insights into further investigations on MSUS in healthy children and in JIA patients are presented and discussed in the present review.

CONCLUSIONS

MSUS shows great promise in the assessment and management of children with JIA. Nonetheless, anatomical knowledge of sonographic changes over time, underlying immunopathophysiology, standardization and validation of MSUS in healthy children and in patients with JIA are still under investigation. Further research and educational efforts are required for expanding this imaging modality to more clinicians in their daily practice.