Histologic and Transcriptional Evidence of Subclinical Synovial Inflammation in Patients With Rheumatoid Arthritis in Clinical Remission

Effective Assessment of Rheumatoid Arthritis Disease Activity and Outcomes Using Monocyte Chemotactic Protein-1 (MCP-1) and Disease Activity Score 28-MCP-1

The effectiveness of monocyte chemotactic protein-1 (MCP-1) and Disease Activity Score 28 (DAS28)-MCP-1 (DAS28-MCP-1) in assessing rheumatoid arthritis (RA) disease activity is unclear, although some studies have demonstrated their potential usefulness. The present study investigated relationships between MCP-1 and different DAS28 measures, the occurrence of residual swollen joints in different DAS28 remission statuses, changes in medication dosage in relation to the 2005 modified American Rheumatism Association and 2011 American College of Rheumatology/European League against Rheumatism (ACR/EULAR) remission definitions, and the correlations between different DAS28-related scores and Health Assessment Questionnaire Disability Index (HAQ-DI) scores in two RA patient cohorts. The results revealed that the MCP-1 level was correlated with five disease activity measures (DAS28-erythrocyte sedimentation rate [DAS28-ESR], DAS28-C-reactive protein [CRP], Simplified Disease Activity Index (SDAI), Clinical Disease Activity Index (CDAI), and DAS28-MCP-1) in multivariable regression analysis (all p < 0.05; ESR, CRP, and MCP-1 as independent variables). However, ESR was not significantly associated with SDAI and CDAI scores (p = 0.343 and 0.323, respectively). Residual swollen joints were more frequently observed in patients who met the DAS28-ESR remission criteria (<2.6) compared with those meeting the other four remission criteria, with a difference ranging from 71% to 94%. Among patients meeting the DAS28-ESR remission criteria (<2.6), medication changes (dose increase by ≥30% or new medications prescribed) were less frequent in those who also met the 2011 ACR/EULAR remission criteria than in those who did not meet them (p = 0.006). Moreover, the correlation coefficients for the relationship between DAS28-ESR and HAQ-DI scores were the lowest among the five disease activity measures. In conclusion, MCP-1 and DAS28-MCP-1 are effective in assessing RA disease activity, with less residual joint swelling and less frequent medication increases observed in the DAS28-MCP-1 remission < 2.2 subgroup.

A radioactive and fluorescent dual modality cysteine cathepsin-B activity-based probe for the detection and treatment evaluation in rheumatoid arthritis

Activated macrophages are key effector cells and specific markers in patients with rheumatoid arthritis (RA). Cysteine cathepsin B (CTS-B) is highly expressed in macrophages and positively associated with RA activity and severity. This study aims to evaluate an activity-based multi-modality diagnostic agent, 68Ga-BMX2, which targets CTS-B to visualize the arthritis activity and evaluate the treatment efficacy. A CTS-B activity-based probe, BMX2, was labeled efficiently with 68Ga to produce 68Ga-BMX2 for fluorescent and positron emission tomography (PET) multi-modality imaging. The affinity and specificity of BMX2 binding with the CTS-B enzyme in macrophages were determined by radioactive experiment using RAW 264.7 cell lines, with CA074 and BMX5 as the inhibitors to test the specificity of the binding. Then, PET and fluorescence imaging were acquired on collagen-induced arthritis (CIA) mice. Additionally, the treatment monitoring capability of 68Ga-BMX2 PET/CT imaging was tested with methotrexate (MTX). RAW 264.7 macrophage cells showed significant uptake of 68Ga-BMX2. The binding of BMX2 with CTS-B in RAW 264.7 macrophage cells is time-dependent and could be blocked by CA074 and BMX5. In vivo optical and PET imaging showed high signals in the right hind arthritis in CIA mice from 68Ga-BMX2 and BMX2 accumulated for at least 120 h. Additionally, 68Ga-BMX2 signals were significantly reduced in the MTX-treated CIA mice compared to the control group. The 68Ga-BMX2, a radioactive and fluorescent dual-modality diagnostic agent targeting CTS-B, demonstrated a practical approach for CIA PET and fluorescence imaging. The 68Ga-BMX2 multimodality imaging could significantly monitor the treatment response in the CIA mice.

Association Between Hyperuricemia and Ultrasound-Detected Hand Synovitis

OBJECTIVE

Although hand synovitis is prevalent in the older population, the etiology remains unclear. Hyperuricemia, a modifiable metabolic disorder, may serve as an underlying mechanism of hand synovitis, but little is known about their relationship. We assessed the association between hyperuricemia and hand synovitis in a large population-based sample.

METHODS

We performed a cross-sectional study in Longshan County, Hunan Province, China. Hyperuricemia was defined as a serum urate level >420 μmol/L in men and >360 μmol/L in women. Ultrasound examinations were performed on both hands of 4,080 participants, and both gray-scale synovitis and the Power Doppler signal (PDS) were assessed using semiquantitative scores (grades 0-3). We evaluated the association of hyperuricemia with hand gray-scale synovitis (grade ≥2) and PDS (grade ≥1), respectively, adjusting for age, sex, and body mass index.

RESULTS

All required assessments for analysis were available for 3,286 participants. The prevalence of hand gray-scale synovitis was higher among participants with hyperuricemia (30.0%) than those with normouricemia (23.3%), with an adjusted odds ratio (aOR) of 1.28 (95% confidence interval [CI] 1.00-1.62). Participants with hyperuricemia also had a higher prevalence of PDS (aOR 2.36; 95% CI 1.15-4.81). Furthermore, hyperuricemia positively associated, both at the hand and joint levels, with the presence of gray-scale synovitis (aOR 1.27; 95% CI 1.00-1.60 and adjusted prevalence ratio [aPR] 1.26; 95% CI 1.10-1.44, respectively) and PDS (aOR 2.35; 95% CI 1.15-4.79 and aPR 2.34; 95% CI 1.28-4.30, respectively).

CONCLUSION

This population-based study provides more evidence for a positive association between hyperuricemia and prevalent hand synovitis.

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.

Associations between hyperuricemia and ultrasound-detected knee synovial abnormalities in middle-aged and older population: a cross-sectional study

OBJECTIVES

Knee synovial abnormalities, potentially treatment targets for knee pain and osteoarthritis, are common in middle-aged and older population, but its etiology remains unclear. We examined the associations between hyperuricemia and knee synovial abnormalities detected by ultrasound in a general population sample.

METHODS

Participants aged ≥ 50 years were from a community-based observational study. Hyperuricemia was defined as serum urate (SU) level > 416 µmol/L in men and > 357 µmol/L in women. Ultrasound of both knees was performed to determine the presence of synovial abnormalities, i.e., synovial hypertrophy, effusion, or Power Doppler signal (PDS). We examined the relation of hyperuricemia to prevalence of knee synovial abnormalities and its laterality, and the dose-response relationships between SU levels and the prevalence of knee synovial abnormalities.

RESULTS

In total, 3,405 participants were included in the analysis. Hyperuricemia was associated with higher prevalence of knee synovial abnormality (adjusted odds ratio [aOR] = 1.21, 95% confidence interval [CI]: 1.02 to 1.43), synovial hypertrophy (aOR = 1.33, 95% CI: 1.05 to 1.68), and effusion (aOR = 1.21, 95% CI: 1.02 to 1.44), respectively. There were dose-response relationships between SU levels and synovial abnormalities. Additionally, the hyperuricemia was more associated with prevalence of bilateral than with that of unilateral knee synovial abnormality, synovial hypertrophy, or effusion; however, no significant association was observed between hyperuricemia and PDS.

CONCLUSION

In this population-based study we found that hyperuricemia was associated with higher prevalence of knee synovial abnormality, synovial hypertrophy and effusion, suggesting that hyperuricemia may play a role in pathogenesis of knee synovial abnormalities.

Computer Vision Analysis of Rheumatoid Arthritis Synovium Reveals Lymphocytic Inflammation Is Associated With Immunoglobulin Skewing in Blood

OBJECTIVE

We sought to develop computer vision methods to quantify aggregates of cells in synovial tissue and compare these with clinical and gene expression parameters.

METHODS

We assembled a computer vision pipeline to quantify five features encompassing synovial cell density and aggregates and compared these with pathologist scores, disease classification, autoantibody status, and RNA expression in a cohort of 156 patients with rheumatoid arthritis (RA) and 149 patients with osteoarthritis (OA).

RESULTS

All five features were associated with pathologist scores of synovial lymphocytic inflammation (P < 0.0001). Three features that related to the cells per unit of tissue were significantly increased in patients with both seronegative and seropositive RA compared with those with OA; on the other hand, aggregate features (number and diameter) were significantly increased in seropositive, but not seronegative, RA compared with OA. Aggregate diameter was associated with the gene expression of immunoglobulin heavy-chain genes in the synovial tissue. Compared with blood, synovial immunoglobulin isotypes were skewed from IGHM and IGHD to IGHG3 and IGHG1. Further, patients with RA with high levels of lymphocytic infiltrates in the synovium demonstrated parallel skewing in their blood with a relative decrease in IGHGM (P < 0.002) and IGHD (P < 0.03) and an increase in class-switched immunoglobulin genes IGHG3 (P < 0.03) and IGHG1 (P < 0.002).

CONCLUSION

High-resolution automated identification and quantification of synovial immune cell aggregates uncovered skewing in the synovium from naïve IGHD and IGHM to memory IGHG3 and IGHG1 and revealed that this process is reflected in the blood of patients with high inflammatory synovium.

Rheumatoid Arthritis from Easy to Complex Disease: From the "2022 GISEA International Symposium"

Rheumatoid Arthritis (RA) is a systemic disease with many different clinical phenotypes. RA could be classified according to disease duration, seropositivity for rheumatoid factor (RF) and/or anti-citrullinated protein antibodies (ACPA), joint subtype, clinical behaviourbehavior and many other subgroups. In this review, we summarize and discuss the multifaceted aspects of RA, focusing on the relationship between autoimmunity status and clinical outcome, achievement of remission and influence on treatment response, from the 2022 International GISEA/OEG Symposium.

Correlation between ultrasonographic scores and American college of rheumatology recommended rheumatoid arthritis disease activity measures: a systematic review and network meta-analysis

BACKGROUND

To validate and facilitate ultrasound examinations on rheumatoid arthritis (RA) disease activity measurements in routine clinical practice.

METHODS

A systematic review and network meta-analysis (NMA) of ultrasound examinations on joints and its correlation with clinical RA disease activity was performed. PubMed, Embase and Cochrane library were searched for literatures published up to May 01st 2021. Bayesian random-effect NMA was conducted to pool the correlations of ultrasonographic assessment scores with composite RA disease activity measurements.

RESULTS

Fifteen studies evaluating twelve different existing ultrasonographic measurements on joints evaluation for RA disease activity scoring were included in this NMA. For comparisons with clinical disease activity index and simplified disease activity index, synovitis gray scale ultrasound 7 joints (GSUS7) demonstrated modest correlation of 0.30[- 0.74, 1.23] and 0.46[- 0.45, 1.15] respectively, followed by synovitis power Doppler ultrasound 7 joints (PDUS7) (0.25[- 0.57, 1.14], 0.31[- 0.46, 1.24]) and power Doppler ultrasound 12 joints (PDUS12) (0.23[- 1.36, 0.83], 0.25[- 1.18, 0.88]). As for disease activity score using 28 joint counts, PDUS12 showed the biggest correlation of 0.53[- 0.09, 1.11], followed by ultrasound 7 joints (US7) (0.50[0.06, 0.93]), PDUS7 (0.49[- 0.24, 1.12]), power Doppler ultrasound 6 joints (PDUS6) (0.42[- 0.29, 1.21]), synovitis PDUS7 (0.47[- 0.09, 1.27]) and synovitis GSUS7 (0.40[0.01, 0.86]).

CONCLUSION

Comparative validity was observed on fewer joints ultrasonic evaluation for RA disease activity measurements, such as synovitis GSUS7 and synovitis PDUS7. Ultrasonographic measurements can be complementary for clinical RA disease activity measures with clinical efficiency, and technical guidelines were in need for clinical routine practice.

Unmet need in rheumatology: reports from the Advances in Targeted Therapies meeting, 2022

To detail the unmet clinical and scientific needs in the field of rheumatology. After a 2-year hiatus due to the SARS-CoV-2 pandemic, the 22nd annual international Advances in Targeted Therapies meeting brought together more than 100 leading basic scientists and clinical researchers in rheumatology, immunology, epidemiology, molecular biology and other specialties. Breakout sessions were convened with experts in five rheumatological disease-specific groups including: rheumatoid arthritis (RA), psoriatic arthritis, axial spondyloarthritis, systemic lupus erythematosus and connective tissue diseases (CTDs). In each group, experts were asked to identify and prioritise current unmet needs in clinical and translational research, as well as highlight recent progress in meeting formerly identified unmet needs. Clinical trial design innovation was emphasised across all disease states. Within RA, developing therapies and trials for refractory disease patients remained among the most important identified unmet needs and within lupus and spondyloarthritis the need to account for disease endotypes was highlighted. The RA group also identified the need to better understand the natural history of RA, pre-RA states and the need ultimately for precision medicine. In CTD generally, experts focused on the need to better identify molecular, cellular and clinical signals of early and undifferentiated disease in order to identify novel drug targets. There remains a strong need to develop therapies and therapeutic strategies for those with treatment-refractory disease. Increasingly it is clear that we need to better understand the natural history of these diseases, including their 'predisease' states, and identify molecular signatures, including at a tissue level, which can facilitate disease diagnosis and treatment. As these unmet needs in the field of rheumatic diseases have been identified based on consensus of expert clinicians and scientists in the field, this document may serve individual researchers, institutions and industry to help prioritise their scientific activities.

Synovial Inflammatory Pathways Characterize Anti-TNF-Responsive Rheumatoid Arthritis Patients

OBJECTIVE

This study was undertaken to understand the mechanistic basis of response to anti-tumor necrosis factor (anti-TNF) therapies and to determine whether transcriptomic changes in the synovium are reflected in peripheral protein markers.

METHODS

Synovial tissue from 46 rheumatoid arthritis (RA) patients was profiled with RNA sequencing before and 12 weeks after treatment with anti-TNF therapies. Pathway and gene signature analyses were performed on RNA expression profiles of synovial biopsies to identify mechanisms that could discriminate among patients with a good response, a moderate response, or no response, according to the American College of Rheumatology (ACR)/EULAR response criteria. Serum proteins encoded by synovial genes that were differentially expressed between ACR/EULAR response groups were measured in the same patients.

RESULTS

Gene signatures predicted which patients would have good responses, and pathway analysis identified elevated immune pathways, including chemokine signaling, Th1/Th2 cell differentiation, and Toll-like receptor signaling, uniquely in good responders. These inflammatory pathways were correspondingly down-modulated by anti-TNF therapy only in good responders. Based on cell signature analysis, lymphocyte, myeloid, and fibroblast cell populations were elevated in good responders relative to nonresponders, consistent with the increased inflammatory pathways. Cell signatures that decreased following anti-TNF treatment were predominately associated with lymphocytes, and fewer were associated with myeloid and fibroblast populations. Following anti-TNF treatment, and only in good responders, several peripheral inflammatory proteins decreased in a manner that was consistent with corresponding synovial gene changes.

CONCLUSION

Collectively, these data suggest that RA patients with robust responses to anti-TNF therapies are characterized at baseline by immune pathway activation, which decreases following anti-TNF treatment. Understanding mechanisms that define patient responsiveness to anti-TNF treatment may assist in development of predictive markers of patient response and earlier treatment options.

Identification of HBEGF+ fibroblasts in the remission of rheumatoid arthritis by integrating single-cell RNA sequencing datasets and bulk RNA sequencing datasets

Background

Fibroblasts are important structural cells in synovium and play key roles in maintaining the synovial homeostasis. By single-cell RNA sequencing (scRNA-seq), subpopulation of synovium-resident cells has been reported to protect intra-articular structures from chronic inflammation and promote tissue repair. However, a significant number of researchers have concentrated on the role of fibroblasts in the progress of rheumatoid arthritis (RA) while few reports had described the contribution of distinct fibroblast subsets in the RA remission. It is helpful to understand the role of fibroblast subpopulations in the RA process to provide predictive biomarkers and address RA remission mechanisms. Here, we found HBEGF+ fibroblasts that contributed to RA remission by integrating scRNA-seq datasets and bulk RNA sequencing (bulk RNA-seq) datasets.

Method

Three single-cell RNA datasets of cells harvested from RA patients were processed and integrated by Seurat and Harmony R packages. After identifying cell types by classic marker genes, the integrated dataset was used to run CellChat for analysis of cell-cell communication. Specially, EGF signaling pathway was found and HBEGF+ fibroblasts were identified based on HBEGF expression. Differential expressed genes of HBEGF+ were shown in heatmap and volcano plot and used to run gene ontology (GO) enrichment analysis. Next, bulk RNA-seq datasets of synovium under different conditions (health, osteoarthritis (OA), rheumatoid arthritis, before and after classical treatment) were compared to show expression change of HBEGF and gene markers that are mainly expressed by HBEGF+ fibroblasts such as CLIC5, PDGFD, BDH2, and ENPP1. Finally, two single-cell RNA sequencing datasets of synovial cells from mice were integrated to identify Hbegf+ fibroblasts and calculate the population of Hbegf+ fibroblasts under different joint conditions (health, K/BxN serum transfer arthritis (STA), and remission of STA).

Result

After integrating three single-cell RNA sequencing datasets, we identified 11 clusters of synovial cells, such as fibroblasts, mural cells, endothelial cells, CD4+ T cells, CD8+ T cells, natural killer cells, synovium macrophage, peripheral blood macrophages, plasma cells, B cells, and STMN1+ cells. We found fibroblasts had an extensive communication network with other clusters and interacted with synovial macrophages through EGF signaling pathway via analysis of cell-cell communication between synovial cells. HBEGF, ligand to EGF signaling pathway, was highly expressed by a subset of fibroblasts and macrophages, and EGFR, receptor to EGF signaling pathway, was highly expressed by fibroblasts and meniscus cells. Moreover, HBEGF was downregulated under RA state and it had an increase after classical treatment. We then defined fibroblasts with high expression of HBEGF as HBEGF+ fibroblasts. In addition, we also found that HBEGF+ fibroblasts highly expressed CRTAC1, ITGB8, SCARA5, THBS4, and ITGBL1, genes relative to encoding extracellular matrix proteins and engaged in positive regulation of cell migration and motility, cellular component movement, and cell growth by GO enrichment analysis. We eventually identified HBEGF+ fibroblasts specially expressed CLIC5, PDGFD, BDH2, and ENPP1, which positively correlated with the expression of HBEGF. Moreover, the expression of CLIC5, PDGFD, BDH2, and ENPP1 was downregulated under RA state and elevated by classical therapy. On the contrary, the HBEGF+ macrophages specially expressed SLAMF8, GK, L1RN, and JAK2, which negatively correlated with the expression of HBEGF. The expression was upregulated in SLAMF8, GK, L1RN, and JAK2 under the RA state, whereas it was decreased after classical treatment. In mice, the number of Hbegf+ fibroblasts was reduced in the RA synovium but increased in the RA remitting synovium.

Conclusions

HBEGF+ fibroblasts play a role in the remission of rheumatoid arthritis, and HBEGF has potential to become a novel biomarker for prediction of RA progress.

Preclinical evaluation and pilot clinical study of [18F]AlF-NOTA-FAPI-04 for PET imaging of rheumatoid arthritis

PURPOSE

Fibroblast-like synoviocytes (FLSs) are key effector cells in the inflamed joints of patients with rheumatoid arthritis (RA). Previous studies have suggested that fibroblast activation protein (FAP) is highly expressed in RA-derived FLSs and is a specific marker of activated RA FLSs. In this study, we developed aluminum-[¹⁸F]-labeled 1,4,7-triazacyclononane-N,N',N″-triacetic acid-conjugated FAP inhibitor 04 ([¹⁸F]AlF-NOTA-FAPI-04) to image RA-FLSs in vitro and arthritic joints in collagen-induced arthritis (CIA) mice and RA patients.

METHODS

RA FLSs and NIH3T3 cells transfected with FAP were used to perform in vitro-binding studies. Biodistribution was conducted in normal DBA1 mice. Collagen-induced arthritis (CIA) models with different arthritis scores were subjected to [¹⁸F]AlF-NOTA-FAPI-04 and ¹⁸F-FDG PET imaging. Histological examinations were performed to evaluate FAP expression and Cy3 dye-labeled FAPI-04(Cy3-FAPI-04) uptake. Blocking studies with excess unlabeled FAPI-04 in CIA mice and NIH3T3 xenografts in immunocompromised mice were used to evaluate the binding specificity of [¹⁸F]AlF-NOTA-FAPI-04. Additionally, [¹⁸F]AlF-NOTA-FAPI-04 PET imaging was performed on two RA patients.

RESULTS

The binding of [¹⁸F]AlF-NOTA-FAPI-04 increased significantly in RA FLSs and NIH3T3 cells overexpressing FAP compared to their parental controls (^FAP-GFP-NIH3T3 vs. ^GFP-NIH3T3, 2.40 ± 0.078 vs. 0.297 ± 0.05% AD/10⁵ cells; RA FLSs vs. OA FLSs, 1.54 ± 0.064 vs. 0.343 ± 0.056% AD/10⁵ cells). Compared to ¹⁸F-FDG imaging, [18F]AlF-NOTA-FAPI-04 showed high uptake in inflamed joints in the early stage of arthritis, which was positively correlated with the arthritic scores (Pearson r=0.834, P<0.001). In addition, the binding of [¹⁸F]AlF-NOTA-FAPI-04 to cells with high FAP expression and the uptake of [¹⁸F]AlF-NOTA-FAPI-04 in arthritic joints both could be blocked by excessive unlabeled FAPI-04. Fluorescent staining showed that the intensity of Cy3-FAPI-04 binding to FAP increased accordingly as the expression of FAP protein increased in cells and tissue sections. Furthermore, the uptake of [¹⁸F]AlF-NOTA-FAPI-04 in ^FAP-GFP-NIH3T3 xenografts was significantly higher than that in ^GFP-NIH3T3 xenograft (35.44 ± 4.27 vs 7.92 ± 1.83% ID/mL). Finally, [¹⁸F]AlF-NOTA-FAPI-04 PET/CT imaging in RA patients revealed nonphysiologically high tracer uptake in the synovium of arthritic joints.

CONCLUSION

[¹⁸F]AlF-NOTA-FAPI-04 is a promising radiotracer for imaging RA FLSs and could potentially complement the current noninvasive diagnostic parameters.

Inside the Joint of Inflammatory Arthritis Patients: Handling and Processing of Synovial Tissue Biopsies for High Throughput Analysis

Inflammatory arthritis is a chronic systemic autoimmune disease of unknown etiology, which affects the joints. If untreated, these diseases can have a detrimental effect on the patient's quality of life, leading to disabilities, and therefore, exhibit a significant socioeconomic impact and burden. While studies of immune cell populations in arthritis patient's peripheral blood have been informative regarding potential immune cell dysfunction and possible patient stratification, there are considerable limitations in identifying the early events that lead to synovial inflammation. The joint, as the site of inflammation and the local microenvironment, exhibit unique characteristics that contribute to disease pathogenesis. Understanding the contribution of immune and stromal cell interactions within the inflamed joint has been met with several technical challenges. Additionally, the limited availability of synovial tissue biopsies is a key incentive for the utilization of high-throughput techniques in order to maximize information gain. This review aims to provide an overview of key methods and novel techniques that are used in the handling, processing and analysis of synovial tissue biopsies and the potential synergy between these techniques. Herein, we describe the utilization of high dimensionality flow cytometric analysis, single cell RNA sequencing, ex vivo functional assays and non-intrusive metabolic characterization of synovial cells on a single cell level based on fluorescent lifetime imaging microscopy. Additionally, we recommend important points of consideration regarding the effect of different storage and handling techniques on downstream analysis of synovial tissue samples. The introduction of new powerful techniques in the study of synovial tissue inflammation, brings new challenges but importantly, significant opportunities. Implementation of novel approaches will accelerate our path toward understanding of the mechanisms involved in the pathogenesis of inflammatory arthritis and lead to the identification of new avenues of therapeutic intervention.

Three-dimensional spatial transcriptomics uncovers cell type localizations in the human rheumatoid arthritis synovium

The inflamed rheumatic joint is a highly heterogeneous and complex tissue with dynamic recruitment and expansion of multiple cell types that interact in multifaceted ways within a localized area. Rheumatoid arthritis synovium has primarily been studied either by immunostaining or by molecular profiling after tissue homogenization. Here, we use Spatial Transcriptomics, where tissue-resident RNA is spatially labeled in situ with barcodes in a transcriptome-wide fashion, to study local tissue interactions at the site of chronic synovial inflammation. We report comprehensive spatial RNA-Seq data coupled to cell type-specific localization patterns at and around organized structures of infiltrating leukocyte cells in the synovium. Combining morphological features and high-throughput spatially resolved transcriptomics may be able to provide higher statistical power and more insights into monitoring disease severity and treatment-specific responses in seropositive and seronegative rheumatoid arthritis.

Clinical utility of quantitative analysis of bone scintigraphy in detecting clinically active joint and high disease activity in patients with rheumatoid arthritis

Background

The purpose of this study was to investigate the efficiency of quantitative parameters of bone scintigraphy in detecting clinically active joint and high disease activity in patients with rheumatoid arthritis.

Methods

We retrospectively enrolled 65 patients with rheumatoid arthritis who underwent bone scintigraphy for diagnostic work-up. Quantitative analysis of bone scintigraphy images was conducted using an in-house software, and joint uptake ratio of 28 joints was measured for the calculation of the disease activity score of 28 joints using erythrocyte sedimentation rate (DAS28-ESR). The relationship between joint uptake ratio and clinical findings and the efficiency of joint uptake ratio in detecting clinically active joint and high disease activity were assessed.

Results

Clinically active joint (tender and/or swollen joints) showed significantly higher joint uptake ratio than did other non-affected joints (p < 0.05). The sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of joint uptake ratio for identifying clinically active joint were 78.7%, 52.0%, 32.9%, and 89.1%, respectively, and those of the summed joint uptake ratio for detecting high disease activity were 92.9%, 66.8%, 43.3%, and 97.1%, respectively; the joint uptake ratio showed high detection ability, especially for active joints of the elbow, wrist, and metacarpo-phalangeal joint areas. The summed joint uptake ratio of 28 joints showed a significantly strong positive correlation with DAS28-ESR (p < 0.001; correlation coefficient, 0.725).

Conclusion

Quantitative parameters of bone scintigraphy showed high sensitivity and NPV for detecting clinically active joint and high disease activity in patients with rheumatoid arthritis.

Clinical utility of F-18 sodium fluoride PET/CT for estimating disease activity in patients with rheumatoid arthritis

Background

The present study aimed to investigate the clinical implication of F-18 sodium fluoride (NaF) positron emission tomography/computed tomography (PET/CT) for assessing the disease activity of rheumatoid arthritis.

Methods

Seventeen patients with rheumatoid arthritis according to the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria were prospectively enrolled. All enrolled patients underwent F-18 NaF PET/CT along with physical examination, blood test, and ultrasonography. On PET/CT images, two quantitative parameters, F-18 NaF uptake of the joint (joint SUV) and joint-to-bone uptake ratio, were measured for each of the 28 joints included in calculating the disease activity score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR). The relationship between PET/CT parameters and clinical factors and the predictive values of PET/CT parameters for joints with synovitis and high disease activity were evaluated.

Results

Tender joints (joint SUV, 13.6±8.4; joint-to-bone uptake ratio, 1.70±1.02) and both tender and swollen joints (joint SUV, 13.9±5.4; joint-to-normal bone uptake ratio, 1.81±0.76) had significantly higher joint SUV and joint-to-bone uptake ratio than joints without synovitis (joint SUV, 6.0±2.4; joint-to-bone uptake ratio, 0.74±0.31; P<0.001). On correlation analysis, summed joint SUV (P=0.002, correlation coefficient=0.705) and summed joint-to-bone uptake ratio (P<0.001, correlation coefficient=0.861) of 28 joints showed strong positive correlation with DAS28-ESR after adjustment for age and body mass index. Summed joint SUV showed significant positive correlations with ultrasonography findings (grey scale ultrasonography: P=0.047, correlation coefficient =0.468; power Doppler ultrasonography: P=0.045, correlation coefficient =0.507). On the receiver operating characteristic curve analysis, the sensitivity and specificity for predicting synovitis were 83.2% and 92.7%, respectively, for joint SUV and 81.5% and 90.7%, respectively, for joint-to-bone uptake ratio. Moreover, the summation of both PET/CT parameters of 28 joints showed a diagnostic accuracy of 100.0% for predicting high disease activity in rheumatoid arthritis.

Conclusions

Summed joint uptake on F-18 NaF PET/CT had a strong positive correlation with DAS28-ESR and accurately predicted high disease activity. F-18 NaF PET/CT parameters might be used as an imaging biomarker for disease activity in rheumatoid arthritis.

Trial registration

This study was registered at the Clinical Research Information Service of the Korea (CRIS, http://cris.nih.go.kr/cris/en; registry number, KCT0002597; registered November 2017).

Patient Reported Outcomes in Chronic Inflammatory Diseases: Current State, Limitations and Perspectives

Chronic inflammatory diseases (CID) are emerging disorders which do not only affect specific organs with respective clinical symptoms but can also affect various aspects of life, such as emotional distress, anxiety, fatigue and quality of life. These facets of chronic disease are often not recognized in the therapy of CID patients. Furthermore, the symptoms and patient-reported outcomes often do not correlate well with the actual inflammatory burden. The discrepancy between patient-reported symptoms and objectively assessed disease activity can indeed be instructive for the treating physician to draw an integrative picture of an individual's disease course. This poses a challenge for the design of novel, more comprehensive disease assessments. In this mini-review, we report on the currently available patient-reported outcomes, the unmet needs in the field of chronic inflammatory diseases and the challenges of addressing these.

Clinical Use of Quantitative Analysis of Bone Scintigraphy to Assess the Involvement of Arthritis Diseases in Patients with Joint Symptoms

We aimed to compare the diagnostic ability of quantitative analysis of bone scintigraphy with that of visual analysis for identifying arthritis disease involvement in patients with joint symptoms. We retrospectively included 93 patients with joint symptoms who underwent Tc-99m methylene diphosphonate bone scintigraphy for evaluating arthritis disease involvement. Bone scintigraphy images were visually and quantitatively analyzed using an in-house software by two reviewers. On quantitative analysis, joint uptake ratio was measured for 64 joints in 14 joints areas. The inter-rater agreement of visual and quantitative analyses was assessed, and diagnostic abilities were compared based on the area under the receiver operating characteristic (ROC) curve (AUC) values. Regarding visual analysis, there was a moderate degree of inter-rater agreement (kappa coefficient of 0.597), while there was a substantial inter-rater agreement (concordance correlation coefficient of 0.987) in the measurement of the joint uptake ratio. The comparisons of ROC curves for the total 5941 joints revealed that the joint uptake ratio had a significantly higher AUC value (0.789) to detect the affected joint than that of the visual analysis (p < 0.001). Quantitative analysis using joint uptake ratio showed substantial reproducibility and higher diagnostic ability to detect joints involving arthritis diseases than visual analysis on bone scintigraphy.

Intensive therapy alleviates subclinical synovitis on ultrasound and disease activity and reduces flare in rheumatoid arthritis patients who have achieved clinical target - a randomized controlled trial

OBJECTIVE

Whether intensive therapy can alleviate subclinical synovitis and reduce flare in rheumatoid arthritis (RA) patients in clinical remission remains unclear. We designed a 1-year open-labelled, randomized controlled clinical trial to elucidate this question.

METHODS

RA patients in clinical remission/low disease activity (defined by DAS28-CRP≤ 3.2), however with subclinical synovitis on ultrasound [power Doppler (PD)≥1 and/or gray scale (GS)≥2] were randomized to receive maintenance or intensive treatment at a ratio of 1:1. The primary outcome was the rate of RA relapse (defined by DAS28-CRP>3.2 and an increase≥0.6). The secondary outcomes were changes of PD and GS scores, and clinical disease activity at each visit from baseline.

RESULTS

108 patients with 54 in each group were enrolled. During 1-year follow-up, the relapse rate was significantly higher in maintenance group than in intensive group, regardless of all enrolled patients or those in remission [24.1% (13/54) vs. 9.1% (5/54), p=0.039; 26.2% (11/42) vs. 5.3% (2/38), p=0.026, respectively]. Although GS and PD scores were decreased at 12 months in both groups, the decline was more remarkable in intensive group than in maintenance group. The improvement of clinical disease activity score was only observed in intensive group, not maintenance group. Adverse events were comparable between two groups. Abnormal liver function tests were observed in 24 (22%) patients with 16 from intensive group.

CONCLUSION

Intensive therapy can alleviate subclinical synovitis on ultrasound and clinical disease activity, and prevent relapse in RA patients who have achieved clinical remission or low disease activity, with comparable safety profiles to maintenance therapy.

REGISTRATION NUMBER

ChiCTR2000029279.