T cells in rheumatoid arthritis

Systematic decoding of cis gene regulation defines context-dependent control of the multi-gene costimulatory receptor locus in human T cells

Cis-regulatory elements (CREs) interact with trans regulators to orchestrate gene expression, but how transcriptional regulation is coordinated in multi-gene loci has not been experimentally defined. We sought to characterize the CREs controlling dynamic expression of the adjacent costimulatory genes CD28, CTLA4 and ICOS, encoding regulators of T cell-mediated immunity. Tiling CRISPR interference (CRISPRi) screens in primary human T cells, both conventional and regulatory subsets, uncovered gene-, cell subset- and stimulation-specific CREs. Integration with CRISPR knockout screens and assay for transposase-accessible chromatin with sequencing (ATAC-seq) profiling identified trans regulators influencing chromatin states at specific CRISPRi-responsive elements to control costimulatory gene expression. We then discovered a critical CCCTC-binding factor (CTCF) boundary that reinforces CRE interaction with CTLA4 while also preventing promiscuous activation of CD28. By systematically mapping CREs and associated trans regulators directly in primary human T cell subsets, this work overcomes longstanding experimental limitations to decode context-dependent gene regulatory programs in a complex, multi-gene locus critical to immune homeostasis.

Mitochondrial functioning in Rheumatoid arthritis modulated by estrogen: Evidence-based insight into the sex-based influence on mitochondria and disease

Alteration of immune response and synovium microvasculature in Rheumatoid arthritis (RA) progression has been suggested to be associated with mitochondrial functioning. Mitochondria, with maternally inherited DNA, exhibit differential response to the female hormone estrogen. Various epidemiological evidence has also shown the prominence of RA in the female population, depicting the role of estrogen in modulating the pathogenesis of RA. As estrogen regulates the expression of differential proteins and associated signaling pathways of RA, its influence on mitochondrial functioning seems evident. Thus, in this review, the studies related to mitochondria and their relation with estrogen and Rheumatoid arthritis were retrieved. We analyzed the different mitochondrial activities that are altered in RA and the possibility of their estrogenic control. The study expands to in silico analysis, revealing the differential mitochondrial proteins expressed in RA and examining these proteins as potential estrogenic targets. It was found that ALDH2, CASP3, and SOD2 are the major mitochondrial proteins involved in RA progression and are also potent estradiol targets. The analysis establishes the role of mitochondrial proteins in RA progression, which were found to be direct or indirect targets of estrogen, depicting its potential for regulating mitochondrial functions in RA.

Single-cell characterisation of tissue homing CD4 + and CD8 + T cell clones in immune-mediated refractory arthritis

BACKGROUND

Immune-mediated arthritis is a group of autoinflammatory diseases, where the patient's own immune system attacks and destroys synovial joints. Sustained remission is not always achieved with available immunosuppressive treatments, warranting more detailed studies of T cell responses that perpetuate synovial inflammation in treatment-refractory patients.

METHODS

In this study, we investigated CD4 + and CD8 + T lymphocytes from the synovial tissue and peripheral blood of patients with treatment-resistant immune-mediated arthritis using paired single-cell RNA and TCR-sequencing. To gain insights into the trafficking of clonal families, we compared the phenotypes of clones with the exact same TCRß amino acid sequence between the two tissues.

RESULTS

Our results show that both CD4 + and CD8 + T cells display a more activated and inflamed phenotype in the synovial tissue compared to peripheral blood both at the population level and within individual T cell families. Furthermore, we found that both cell subtypes exhibited clonal expansion in the synovial tissue.

CONCLUSIONS

Our findings suggest that the local environment in the synovium drives the proliferation of activated cytotoxic T cells, and both CD4 + and CD8 + T cells may contribute to tissue destruction and disease pathogenesis.

Rheumatoid arthritis molecular targets and their importance to flavonoid-based therapy

Rheumatoid arthritis (RA) is a progressive, chronic, autoimmune, inflammatory, and systemic condition that primarily affects the synovial joints and adjacent tissues, including bone, muscle, and tendons. The World Health Organization recognizes RA as one of the most prevalent chronic inflammatory diseases. In the last decade, there was an expansion on the available RA therapeutic options which aimed to improve patient's quality of life. Despite the extensive research and the emergence of new therapeutic approaches and drugs, there are still significant unwanted side effects associated to these drugs and still a vast number of patients that do not respond positively to the existing therapeutic strategies. Over the years, several references to the use of flavonoids in the quest for new treatments for RA have emerged. This review aimed to summarize the existing literature about the flavonoids' effects on the major pathogenic/molecular targets of RA and their potential use as lead compounds for the development of new effective molecules for RA treatment. It is demonstrated that flavonoids can modulate various players in synovial inflammation, regulate immune cell function, decrease synoviocytes proliferation and balance the apoptotic process, decrease angiogenesis, and stop/prevent bone and cartilage degradation, which are all dominant features of RA. Although further investigation is necessary to determine the effectiveness of flavonoids in humans, the available data from in vitro and in vivo models suggest their potential as new disease-modifying anti-rheumatic drugs. This review highlights the use of flavonoids as a promising avenue for future research in the treatment of RA.

Adenosine metabolic signature in circulating CD4+ T cells predicts remission in rheumatoid arthritis

OBJECTIVES

Long-term outcomes in rheumatoid arthritis (RA) depend on early and effective disease control. Methotrexate (MTX) remains the first-line disease modifying therapy, however there are no biomarkers with which to identify those most likely to achieve remission. To address this unmet need we explored metabolic pathways involved in MTX mechanism of action within circulating CD4+T cells in a cohort of treatment naive patients with early RA.

METHODS

Purified CD4+T cells were isolated from peripheral blood of 68 patients with early RA commencing MTX. The expression of a range of putative MTX metabolism and mechanism of action targets were explored by flow-cytometry and transcriptional analysis. From these data significant predictors of Disease Activity Score 28-C reactive protein (DAS28-CRP) remission (<2.4 at 6 months) were determined by logistic regression (clinical; flow-cytometry data) and linear modelling (gene expression data).

RESULTS

Low baseline DAS28-CRP was associated with remission at 6 months (p=0.02). Expression of the ectonucleotidase CD39, involved in ATP-ADP conversion during adenosine synthesis, was higher on CD4+CD25 High regulatory T cells at baseline in those achieving remission (molecules of equivalent fluorescence 1264 vs 847; p=0.007). Expression of other adenosine signalling elements in CD4+T cells were also upregulated at baseline in patients achieving remission: AMPD1 (p<0.001), ADORA2b (p=0.039) and ADORA3 (p=0.047). When combined into a single predictive metric, a combination of these variables outperformed baseline DAS28-CRP in prediction of early remission (area under the curve 0.92 vs 0.67, p=0.001) CONCLUSIONS: Adenosine signalling is important in the achievement of early remission with MTX in RA and biomarkers of adenosine activity may hold utility for the stratification of therapy in early disease.

Immune checkpoints in rheumatoid arthritis: progress and promise

Rheumatoid arthritis (RA) is one of the most prevalent autoimmune inflammatory conditions, and while the mechanisms driving pathogenesis are yet to be completely elucidated, self-reactive T cells and immune checkpoint pathways have a clear role. In this review, we provide an overview of the importance of checkpoint pathways in the T cell response and describe the involvement of these in RA development and progression. We discuss the relationship between immune checkpoint therapy in cancer and autoimmune adverse events, draw parallels with the involvement of immune checkpoints in RA pathobiology, summarise emerging research into some of the lesser-known pathways, and the potential of targeting checkpoint-related pathways in future treatment approaches to RA management.

Crosstalk between synovial macrophages and fibroblasts in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease associated with chronic inflammation of joints. Abnormally activated cells such as synovial macrophages and synovial fibroblasts induce RA pathogenesis and ultimately joint destruction. Since macrophages can change their own characteristics depending on the microenvironmental condition, it has been suggested that activation and remission of RA are regulated by crosstalk between synovial macrophages and other cells. Moreover, recent findings of heterogeneity of synovial macrophages and fibroblasts support the idea that complex interactions regulate RA from its onset to remission. Importantly, an understanding of the intercellular crosstalk in RA is far from complete. Here, we summarize the molecular mechanisms underlying the pathological development of RA with particular reference to the crosstalk between synovial macrophages and fibroblasts.

Role of mitochondrial dysfunction in the pathogenesis of rheumatoid arthritis: Looking closely at fibroblast- like synoviocytes

Rheumatoid arthritis (RA) is a chronic, autoimmune, and inflammatory disease that primarily targets the joints, leading to cartilage and bone destruction.Fibroblast-like synoviocytes (FLS) are specialized cells of the synovial lining in the joint that plays a fundamental role in the development of RA. Particularly, FLS of RA patients (RA-FLS) in the joint exhibit specific characteristics like higher invading and immunogenic properties, hyperproliferation, and reduced apoptotic capacity, suggesting a dysfunctional mitochondrial pool in these cells. Mitochondria are emerging as a potential organelle that can decide cellular immunometabolism, invasion properties, and cell death. Accordingly, multiplestudies established that mitochondria are crucial in establishing RA. However, the underlying mechanism of impaired mitochondrial function in RA remains poorly understood. This review will provide an overview of the mitochondrial role in the progression of RA, specifically in the context of FLS biology. We will also outline how mitochondria-centric therapeutics can be achieved that would yield novel avenues of research in pathological mediation and prevention.

Expansion of human bone marrow-derived mesenchymal stromal cells with enhanced immunomodulatory properties

BACKGROUND

Mesenchymal stromal cells (MSCs) have broad potential as a cell therapy including for the treatment of drug-resistant inflammatory conditions with abnormal T cell proliferation such as graft-versus-host disease (GVHD). Clinical success, however, has been complicated by the heterogeneity of culture-expanded MSCs as well as donor variability. Here, we devise culture conditions that promote expansion of MSCs with enhanced immunomodulatory functions both in vitro and in animal models of GVHD.

METHODS

Human bone marrow-derived MSCs were expanded at high-confluency (MSCHC) and low-confluency state (MSCLC). Their immunomodulatory properties were evaluated with in vitro co-culture assays based on suppression of activated T cell proliferation and secretion of pro-inflammatory cytokines from activated T cells. Metabolic state of these cells was determined, while RNA sequencing was performed to explore transcriptome of these MSCs. Ex vivo expanded MSCHC or MSCLC was injected into human peripheral blood mononuclear cells (PBMC)-induced GVHD mouse model to determine their in vivo therapeutic efficacy based on clinical grade scoring, human CD45+ blood count and histopathological examination.

RESULTS

As compared to MSCLC, MSCHC significantly reduced both the proliferation of anti-CD3/CD28-activated T cells and secretion of pro-inflammatory cytokines upon MSCHC co-culture across several donors even in the absence of cytokine priming. Mechanistically, metabolic analysis of MSCHC prior to co-culture with activated T cells showed increased glycolytic metabolism and lactate secretion compared to MSCLC, consistent with their ability to inhibit T cell proliferation. Transcriptome analysis further revealed differential expression of immunomodulatory genes including TRIM29, BPIFB4, MMP3 and SPP1 in MSCHC as well as enriched pathways including cytokine-cytokine receptor interactions, cell adhesion and PI3K-AKT signalling. Lastly, we demonstrate in a human PBMC-induced GVHD mouse model that delivery of MSCHC showed greater suppression of inflammation and improved outcomes compared to MSCLC and saline controls.

CONCLUSION

Our study provides evidence that ex vivo expansion of MSCs at high confluency alters the metabolic and transcriptomic states of these cells. Importantly, this approach maximizes the production of MSCs with enhanced immunomodulatory functions without priming, thus providing a non-invasive and generalizable strategy for improving the use of MSCs for the treatment of inflammatory diseases.

Disease-microenvironment modulation by bare- or engineered-exosome for rheumatoid arthritis treatment

BACKGROUND

Exosomes are extracellular vesicles secreted by eukaryotic cells and have been extensively studied for their surface markers and internal cargo with unique functions. A deeper understanding of exosomes has allowed their application in various research areas, particularly in diagnostics and therapy.

MAIN BODY

Exosomes have great potential as biomarkers and delivery vehicles for encapsulating therapeutic cargo. However, the limitations of bare exosomes, such as rapid phagocytic clearance and non-specific biodistribution after injection, pose significant challenges to their application as drug delivery systems. This review focuses on exosome-based drug delivery for treating rheumatoid arthritis, emphasizing pre/post-engineering approaches to overcome these challenges.

CONCLUSION

This review will serve as an essential resource for future studies to develop novel exosome-based therapeutic approaches for rheumatoid arthritis. Overall, the review highlights the potential of exosomes as a promising therapeutic approach for rheumatoid arthritis treatment.

Vaccines prevent reinduction of rheumatoid arthritis symptoms in collagen-induced arthritis mouse model

Metabolic reprogramming of immune cells modulates their function and reduces the severity of autoimmune diseases. However, the long-term effects of the metabolically reprogrammed cells, specifically in the case of immune flare-ups, need to be examined. Herein, a re-induction rheumatoid arthritis (RA) mouse model was developed by injecting T-cells from RA mice into drug-treated mice to recapitulate the effects of T-cell-mediated inflammation and mimic immune flare-ups. Immune metabolic modulator paKG(PFK15 + bc2) microparticles (MPs) were shown to reduce clinical symptoms of RA in collagen-induced arthritis (CIA) mice. Upon re-induction, a significant delay in the reappearance of clinical symptoms in the paKG(PFK15 + bc2) microparticle treatment group was observed as compared to equal or higher doses of the clinically utilized U.S. Food and Drug Administration (FDA)-approved drug, Methotrexate (MTX). Furthermore, paKG(PFK15 + bc2) microparticle-treated mice were able to lower activated dendritic cells (DCs) and inflammatory T helper cell 1 (TH1) and increased activated, proliferating regulatory T-cells (Tregs) more effectively than MTX. The paKG(PFK15 + bc2) microparticles also led to a significant reduction in paw inflammation in mice as compared to MTX treatment. This study can pave the way for the development of flare-up mouse models and antigen-specific drug treatments.

Association of rheumatoid arthritis with bronchial asthma and asthma-related comorbidities: A population-based national surveillance study

Background

The aim of this study was to investigate the impact of rheumatoid arthritis (RA) on the prevalence of bronchial asthma and asthma-related comorbidities. We also aimed to identify the influence of RA on interrelationship between asthma and asthma-related comorbidities.

Methods

From the Korean National Health and Nutrition Examination Survey, participants &gt;40 years of age who completed questionnaires and spirometry tests were enrolled. Patient data on RA, asthma, allergic rhinitis, atopic dermatitis, chronic obstructive pulmonary disease (COPD), sinusitis, otitis media, and body mass index (BMI) were collected. Logistic regression and network analyses were performed.

Results

A total of 14,272 subjects were enrolled, among which, 334 (2.4%) had RA. RA was significantly associated with asthma (OR 2.32; 95% CI 1.51–3.57), allergic rhinitis (OR 1.51; 95% CI 1.08–2.10), and sinusitis (OR 1.64; 95% CI 1.08–2.50). The network analysis of total patients revealed a positive interrelationship between asthma and allergic rhinitis, sinusitis, otitis media, atopic dermatitis, BMI, and RA. The interrelationship between asthma and sinusitis was stronger in the RA group. Of note, the relationship between asthma and BMI was distinctively found only in the RA group (r = 0.214, P &lt; 0.05). In patients with asthma, the prevalence of obesity was 64% in the presence of RA, and 40% in the absence of RA (P = 0.034).

Conclusion

This study supports the positive association of RA with asthma, allergic rhinitis, and sinusitis. Our analysis suggests a notable interrelationship between the presence of asthma and higher BMI values in patients with RA, indicating that asthma is more obesity-related in patients with RA.

Rheumatoid arthritis and non-coding RNAs; how to trigger inflammation

Rheumatoid arthritis (RA) is a systemic and chronic inflammatory disease categorized by continuous synovitis in the joints and systemic inflammatory responses that can cause lifelong disability. The major cause of RA is the dysregulation of the immune response. The development of RA disease includes multiplex association of several interleukins and cells, which leads to synovial cell growth, cartilage and bone damage. The primary stage of RA disease is related to the modification of both the innate and adaptive immune systems, which leads to the formation of autoantibodies. This process results in many damaged molecules and epitope spreading. Both the innate (e.g., dendritic cells, macrophages, and neutrophils) and acquired immune cells (e.g., T and B lymphocytes) will increase and continue the chronic inflammatory condition in the next stages of the RA disease. In recent years, non-coding RNAs have been proved as significant controllers of biological functions, especially immune cell expansion and reactions. Non-coding RNAs were primarily containing microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA). Various studies confirmed non-coding RNAs as hopeful markers for diagnosing and curing RA. This review will describe and cover existing knowledge about RA pathogenesis, which might be favorable for discovering possible ncRNA markers for RA.

V-set domain containing T-cell activation inhibitor-1 (VTCN1): A potential target for the treatment of autoimmune diseases

Autoimmunity eventuates when the immune system attacks self-molecules as a result of the breakdown in immune tolerance. Targeting autoimmune diseases via immunomodulation has become an essential strategy in today's era. A B7 superfamily member immune checkpoint, the V-set domain containing T-cell activation inhibitor-1 (VTCN1), also known as B7-H4, B7S1, and B7x, is involved in negatively regulating T-cell activation. VTCN1 transcript has been reported in various lymphoid and non-lymphoid tissues, but its protein expression is restricted, indicating its translational regulation. Dysregulation of VTCN1 has resulted in the exacerbation of various autoimmune diseases. Moreover, increased soluble form of VTCN1 in the patient's sera positively correlates with the disease progression and severity. The current review summarizes all the reports till date, unfolding the role of VTCN1 in various autoimmune diseases and its therapeutic potential.

Pharmacological Aspects of Natural Quercetin in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that can lead to severe joint damage, disability and mortality. Quercetin (QUE) is a natural flavonoid that is ubiquitous in fruits and vegetables. This article reviews the effect of QUE on articular and extra-articular manifestations of RA in vitro and in vivo. In general, for articular manifestations, QUE inhibited synovial membrane inflammation by reducing inflammatory cytokines and mediators, decreasing oxidative stress, inhibiting proliferation, migration and invasion, and promoting apoptosis of fibroblast-like synoviocytes (FLS), regulated autoimmune response through modulating Th17/Treg imbalance and Th17 cells differentiation, reducing autoantibodies levels and regulating ectonucleoside triphosphate diphosphohydrolase (E-NTPDase)/ectoadenosine deaminase (E-ADA) activities, reduced bony damage via lowering matrix metalloproteinase (MMP)-1, MMP-3, receptor activator of nuclear factor kappa B ligand (RANKL) expression and osteoclasts formation. For extra-articular manifestations, QUE could reverse the neurodegenerative processes of the enteric nervous system (ENS) and exhibited cytoprotective, genoprotective and hepatoprotective effects. In addition, we also summarize some contradictory experimental results and explore the possibility for these differences to form a sound basis for the clinical application of QUE for RA.

Increased Frequency of CD4+ Follicular Helper T and CD8+ Follicular T Cells in Human Lymph Node Biopsies during the Earliest Stages of Rheumatoid Arthritis

Follicular T helper cells (Tfh cells) provide key B-cell help and are essential in germinal center formation and (auto) antibody generation. To gain more insight into their role during the earliest phase of rheumatoid arthritis (RA), we analyzed their frequencies, phenotypes, and cytokine profiles in peripheral blood and lymph node biopsies of healthy controls (HCs), autoantibody-positive individuals at risk for developing RA (RA-risk individuals), and early RA patients. Subsequently, we confirmed their presence in lymph nodes and synovial tissue of RA patients using immunofluorescence microscopy. In the blood, the frequency of Tfh cells did not differ between study groups. In lymphoid and synovial tissues, Tfh cells were localized in B-cell areas, and their frequency correlated with the frequency of CD19⁺ B cells. Compared to lymphoid tissues of healthy controls, those of RA patients and RA-risk individuals showed more CD19⁺ B cells, CD4⁺CXCR5⁺ follicular helper T cells, and CD8⁺CXCR5⁺ follicular T cells. These Tfh cells produced less IL-21 upon ex vivo stimulation. These findings suggest that Tfh cells may present a novel rationale for therapeutic targeting during the preclinical stage of RA to prevent further disease progression.

Local inhibition of TGF-β1 signaling improves Th17/Treg balance but not joint pathology during experimental arthritis

TGF-β1 is an important growth factor to promote the differentiation of T helper 17 (Th17) and regulatory T cells (Treg). The potential of TGF-β1 as therapeutic target in T cell-mediated diseases like rheumatoid arthritis (RA) is unclear. We investigated the effect of TGF-β1 inhibition on murine Th17 differentiation in vitro, on human RA synovial explants ex vivo, and on the development of experimental arthritis in vivo. Murine splenocytes were differentiated into Th17 cells, and the effect of the TGF-βRI inhibitor SB-505124 was studied. Synovial biopsies were cultured in the presence or absence of SB-505124. Experimental arthritis was induced in C57Bl6 mice and treated daily with SB-505124. Flow cytometry analysis was performed to measure different T cell subsets. Histological sections were analysed to determine joint inflammation and destruction. SB-505124 potently reduced murine Th17 differentiation by decreasing Il17a and Rorc gene expression and IL-17 protein production. SB-505124 significantly suppressed IL-6 production by synovial explants. In vivo, SB-505124 reduced Th17 numbers, while increased numbers of Tregs were observed. Despite this skewed Th17/Treg balance, SB-505124 treatment did not result in suppression of joint inflammation and destruction. Blocking TGF-β1 signalling suppresses Th17 differentiation and improves the Th17/Treg balance. However, local SB-505124 treatment does not suppress experimental arthritis.

Fibrinogen-Like Protein 1 Serves as an Anti-Inflammatory Agent for Collagen-Induced Arthritis Therapy in Mice

Fibrinogen-like protein 1 (FGL1) was recently identified as a major ligand of lymphocyte-activation gene-3 (LAG-3) on activated T cells and serves as an immune suppressive molecule for regulation of immune homeostasis. However, whether FGL1 has therapeutic potential for use in the T cell-induced the autoimmune disease, rheumatoid arthritis (RA), is still unknown. Here, we attempted to evaluate the effect of FGL1 protein on arthritis progression. We also evaluated potential adverse events in a collagen-induced arthritis (CIA) mouse model. We first confirmed that soluble Fgl1 protein could specifically bind to surface Lag-3 receptor on 3T3-Lag-3 cells and further inhibit interleukin (IL-2) and interferon gamma (IFNγ) secretion from activated primary mouse T cells by 95% and 43%, respectively. Intraperitoneal administration of Fgl1 protein significantly decreased the inflammatory cytokine level (i.e., IL-1β and IL-6) in local paw tissue, and prevented joint inflammation, cellular infiltration, bone deformation and attenuated collagen-induced arthritis progression in vivo. We further demonstrated that exogenous Fgl1 does not cause obvious adverse events during treatment by monitoring body weight and liver weight, and assessing the morphology of several organs (i.e., heart, liver, spleen, lung and kidney) by pathological studies. We expect that Fgl1 protein may be suitable to serve as a potential therapeutic agent for treatment of RA or even other types of T cell-induced autoimmune or inflammatory diseases in the future.

Defining the Optimal Strategies for Achieving Drug-Free Remission in Rheumatoid Arthritis: A Narrative Review

Background: It is now accepted that the optimum treatment goal for rheumatoid arthritis (RA) is sustained remission, as this has been shown to be associated with the best patient outcomes. There is little guidance on how to manage patients once remission is achieved; however, it is recommended that patients can taper therapy, with a view to discontinuing and achieving drug-free remission if treatment goals are maintained. This narrative review aims to present the current literature on drug-free remission in rheumatoid arthritis, with a view to identifying which strategies are best for disease-modifying anti-rheumatic drug (DMARD) tapering and to highlight areas of unmet clinical need. Methods: We performed a narrative review of the literature, which included research articles, meta-analyses and review papers. The key search terms included were rheumatoid arthritis, remission, drug-free remission, b-DMARDS/biologics, cs-DMARDS and tapering. The databases that were searched included PubMed and Google Scholar. For each article, the reference section of the paper was reviewed to find additional relevant articles. Results: It has been demonstrated that DFR is possible in a proportion of RA patients achieving clinically defined remission (both on cs and b-DMARDS). Immunological, imaging and clinical associations with/predictors of DFR have all been identified, including the presence of autoantibodies, absence of Power Doppler (PD) signal on ultrasound (US), lower disease activity according to composite scores of disease activity and lower patient-reported outcome scores (PROs) at treatment cessation. Conclusions: DFR in RA may be an achievable goal in certain patients. This carries importance in reducing medication-induced side-effects and potential toxicity, the burden of taking treatment if not required and cost effectiveness, specifically for biologic therapy. Prospective studies of objective biomarkers will help facilitate the prediction of successful treatment discontinuation.

Optimization of Human Mesenchymal Stem Cells for Rheumatoid Arthritis: Implications for Improved Therapeutic Outcomes

Objective

Seropositive rheumatoid arthritis (RA) is a chronic autoimmune disease that is rarely “cured.” Human mesenchymal stem cells (hMSCs) are known to reduce inflammation and restore immune homeostasis. However, methods for predicting therapeutic hMSC potency have not been established. The goal of these studies was to use and refine an ex vivo functional assay that determines potency of hMSCs and can then be validated in clinical trials as a potency measure of hMSCs used therapeutically to treat RA.

Methods

Allogeneic hMSCs were cytokine‐stimulated, and a conditioned medium (CM) was harvested. The CM was tested for the potential to attenuate RA CD4+ T cell proliferation using suppression assays. Indoleamine 2, 3‐dioxygenase (IDO) mRNA, and protein were quantified in hMSCs as a measure to compare hMSCs across (prior) studies.

Results

To mimic a proinflammatory environment that resembles that in RA, interleukin‐1(IL1β), tumor necrosis factor α (TNFα), and interferon γ (IFNγ) (alone or in combination) were used to precondition hMSCs. Treating hMSCs with a combination of these cytokines generated a CM “secretome” that suppressed T cell proliferation between 70 and 83%. Forty‐eight hours of cytokine preconditioning hMSCs was required to maximize this effect. T cell suppression positively correlated with increases in hMSC cellular IDO mRNA and protein.

Conclusion

By standardizing assays to measure hMSC effects, their potency on T cell suppression can be quantified. These studies demonstrate that hMSCs can be compared functionally to identify optimal preparation(s) for therapeutic use in RA and that the potency of hMSC‐dependent T cell suppression may differ between hMSC donors. Clinical studies are warranted to validate the hypothesis that ex vivo potency in suppressing T cells will positively correlate with a reduction in RA disease activity and increase in immunological quiescence.

Association between the interleukin (IL)-17A rs2275913 polymorphism and rheumatoid arthritis susceptibility: a meta-analysis and trial sequential analysis

Objective

This meta-analysis was conducted to investigate the relationship between the interleukin (IL)-17A rs2275913 polymorphism and rheumatoid arthritis (RA) susceptibility.

Methods

Eligible studies were retrieved from PubMed, Embase, and Web of Science. The fixed- or random-effects model was used to calculate the pooled odds ratios (ORs) and 95% confidence intervals (95%CIs) on the basis of heterogeneity.

Results

Overall, 11 studies containing 4019 RA patients and 4137 controls were included in this meta-analysis. The results suggested a significant association between the IL-17A rs2275913 polymorphism and RA susceptibility in the overall population (allelic model A vs. G: OR = 0.89, 95%CI: 0.83–0.95; heterozygote model GA vs. GG: OR = 0.87, 95%CI: 0.78–0.96; homozygote model AA vs. GG: OR = 0.82, 95%CI: 0.71–0.96; dominant model GA + AA vs. GG: OR = 0.86, 95%CI: 0.78–0.94). In the subgroup analyses, the IL-17A rs2275913 polymorphism was significantly associated with RA risk in Europeans (allelic model A vs. G: OR = 0.87, 95%CI: 0.78–0.97; heterozygote model GA vs. GG: OR = 0.79, 95%CI: 0.68–0.93; dominant model GA + AA vs. GG: OR = 0.79, 95%CI: 0.68–0.92), but not in Africans or Americans.

Conclusion

This study suggests that the IL-17A rs2275913 polymorphism is significantly associated with RA susceptibility in Europeans.

INPLASY registration number: INPLASY202170056.

Detection of circulating highly expanded T-cell clones in at-risk individuals for rheumatoid arthritis before the clinical onset of the disease

OBJECTIVES

To quantitatively profile the T-cell repertoire in the peripheral blood of individuals genetically at risk for RA, namely first-degree relatives of RA patients (RA-FDR) at different phases of disease development.

METHODS

Next-generation sequencing of the TCR CDR3β repertoire was performed on genomic DNA isolated from whole blood samples of RA-FDR selected at three different pre-clinical stages and of matched RA patients (n = 20/group). T-cell clones were identified by their unique sequence and their degree of expansion (frequency) within each sample was characterized. Clones with a frequency over 0.5% were considered highly expanded clones (HEC).

RESULTS

The absolute number of HEC was significantly higher in established RA patients (mean 4.65) and tended to be higher in symptomatic RA-FDR (mean 3.4) compared with asymptomatic RA-FDR (mean 1.55, P =0.003 and P =0.07, respectively). Asymptomatic individuals with high levels of ACPA did not differ from asymptomatic RA-FDR in terms of absolute number and frequency of clones. The number of HEC tended to be slightly higher at the time of RA onset (P =0.055). Neither clones shared by several patients, nor clones previously associated with RA, were preferentially present within or between the different groups. Finally, a longitudinal analysis did not allow to uncover a kinetic expansion of RA-specific clones closely correlated with disease development.

CONCLUSIONS

HEC were detected in the peripheral blood before the clinical onset of RA, in particular in the later pre-clinical phase of RA development, and their presence increased over time.

Modulation of PTPN2/22 Function by Spermidine in CRISPR-Cas9-Edited T-Cells Associated with Crohn's Disease and Rheumatoid Arthritis

Crohn's Disease (CD) and Rheumatoid Arthritis (RA) share some single nucleotide polymorphisms (SNPs) in protein tyrosine phosphatase non-receptor types 2 and 22 (PTPN2/22). Recently, we reported that clinical samples from CD and RA patients associated with PTPN2:rs478582 or PTPN22:rs2476601 genotypes were linked to overactive immune response and exacerbation of inflammation. Here, we investigated in vitro the effects of these SNPs in Jurkat T-cells using CRISPR-Cas9. All cells were evaluated for PTPN22/22 loss of function and effects on cell response. We measured gene expression via RT-qPCR and cytokines by ELISA. We also measured cell proliferation using a BrdU labeling proliferation ELISA, and T-cell activation using CD-25 fluorescent immunostaining. In PTPN2 SNP-edited cells, PTPN2 expression decreased by 3.2-fold, and proliferation increased by 10.2-fold compared to control. Likewise, expression of PTPN22 decreased by 2.4-fold and proliferation increased by 8.4-fold in PTPN22 SNP-edited cells. IFN-γ and TNF-α secretions increased in both edited cell lines. CD25 expression (cell activation) was 80.32% in PTPN2 SNP-edited cells and 85.82% in PTPN22 SNP-edited cells compared to 70.48% in unedited Jurkat T-cells. Treatment of PTPN2 and PTPN22-edited cells with a maximum 20 μM spermidine restored PTPN2/22 expression and cell response including cell proliferation, activation, and cytokines secretion. Most importantly, the effect of spermidine on edited cells restored normal expression and secretion of IFN-γ and TNF-α. The data clearly demonstrated that edited SNPs in PTPN2 or PTPN22 were associated with reduced gene expression, which resulted in an increase in cell proliferation and activation and overactive immune response. The data validated our earlier observations in CD and RA clinical samples. Surprisingly, spermidine restored PTPN2/22 expression in edited Jurkat T-cells and the consequent beneficial effect on cell response and inflammation. The study supports the use of polyamines dietary supplements for management of CD and in RA patients.

Qing-Luo-Yin Alleviated Monocytes/Macrophages-Mediated Inflammation in Rats with Adjuvant-Induced Arthritis by Disrupting Their Interaction with (Pre)-Adipocytes Through PPAR-γ Signaling

Background

The Chinese herbal formula Qing-Luo-Yin (QLY) has been successfully used in rheumatoid arthritis treatment for decades. It exhibits notable immune and metabolism regulatory properties. Thereby, we investigated its effects on the interplay between (pre)-adipocytes and monocytes/macrophages under adjuvant-induced arthritis (AIA) circumstances.

Methods

Fat reservoir and histological characteristics of white fat tissues (WAT) in AIA rats receiving QLY treatment were examined upon sacrifice. Metabolic parameters, clinical indicators, and oxidative stress levels were determined using corresponding kits, while mRNA/protein expression was investigated by PCR and immunoblotting methods. M1 macrophage distribution in WAT was assessed by flow cytometry. The effects of QLY on (pre)-adipocytes were further validated by experiments in vitro.

Results

Compared with normal healthy controls, body weight and circulating triglyceride were declined in AIA rats, but serological levels of free fatty acids and low-density lipoprotein cholesterol were increased. mRNA IL-1β and iNOS expression in white blood cells and rheumatoid factor, C-reactive protein, anti-cyclic citrullinated peptide antibody, MCP-1 and IL-1β production in serum/WAT were up-regulated. Obvious CD86⁺CD11b⁺ macrophages were enriched in WAT. Meanwhile, expression of PPAR-γ and SIRT1 and secretion of adiponectin and leptin in these AIA rats were impaired. QLY restored all these pathological changes. Of note, it significantly stimulated PPAR-γ expression in the treated AIA rats. Accordingly, QLY-containing serum promoted SCD-1, PPAR-γ, and SIRT1 expression in pre-adipocytes cultured in vitro. AIA rats-derived peripheral blood mononuclear cells suppressed PPAR-γ and SCD-1 expression in co-cultured pre-adipocytes, but serum from AIA rats receiving QLY treatment did not exhibit this potential. The changes on PPAR-γ expression eventually resulted in varied adipocyte differentiation statuses. PPAR-γ selective inhibitor T0070907 abrogated QLY-induced MCP-1 production decline in LPS-primed pre-adipocytes and reduced adiponectin secretion.

Conclusion

QLY was potent in promoting PPAR-γ expression and consequently disrupted inflammatory feedback in WAT by altering monocytes/macrophages polarization and adipocytes differentiation.

Comparative Analysis on Abnormal Methylome of Differentially Expressed Genes and Disease Pathways in the Immune Cells of RA and SLE

We identified abnormally methylated, differentially expressed genes (DEGs) and pathogenic mechanisms in different immune cells of RA and SLE by comprehensive bioinformatics analysis. Six microarray data sets of each immune cell (CD19⁺ B cells, CD4⁺ T cells and CD14⁺ monocytes) were integrated to screen DEGs and differentially methylated genes by using R package “limma.” Gene ontology annotations and KEGG analysis of aberrant methylome of DEGs were done using DAVID online database. Protein-protein interaction (PPI) network was generated to detect the hub genes and their methylation levels were compared using DiseaseMeth 2.0 database. Aberrantly methylated DEGs in CD19⁺ B cells (173 and 180), CD4⁺ T cells (184 and 417) and CD14⁺ monocytes (193 and 392) of RA and SLE patients were identified. We detected 30 hub genes in different immune cells of RA and SLE and confirmed their expression using FACS sorted immune cells by qPCR. Among them, 12 genes (BPTF, PHC2, JUN, KRAS, PTEN, FGFR2, ALB, SERB-1, SKP2, TUBA1A, IMP3, and SMAD4) of RA and 12 genes (OAS1, RSAD2, OASL, IFIT3, OAS2, IFIH1, CENPE, TOP2A, PBK, KIF11, IFIT1, and ISG15) of SLE are proposed as potential biomarker genes based on receiver operating curve analysis. Our study suggests that MAPK signaling pathway could potentially differentiate the mechanisms affecting T- and B- cells in RA, whereas PI3K pathway may be used for exploring common disease pathways between RA and SLE. Compared to individual data analyses, more dependable and precise filtering of results can be achieved by integrating several relevant data sets.

Decreased Levels of STAT1 and Interferon-γ-Induced STAT1 Phosphorylation in Rheumatoid Arthritis CD4 and CD8 T Cells

Objective

We investigated whether a previously reported association of IFNGR expression with rheumatoid arthritis (RA) and its radiographic severity reflects differences in proximal interferon‐γ (IFN‐γ) signaling in T cells from patients with RA compared with healthy controls (HC).

Methods

Using phosphoflow cytometry, we compared IFN‐γ–stimulated signal transducer and activator of transcription 1 (STAT1) activation in CD4⁺ and CD8⁺ T‐cell populations from patients with RA and HC.

Results

Compared with controls, patients with RA had a higher proportion of CD4⁺ T cells, associated with expansion of the CD4⁺ effector memory subset. Several CD4⁺ T‐cell types exhibited reduced IFN‐γ–induced phosphoSTAT1^Y701 (pSTAT1^Y701) in patients with RA compared with HC. Engaging the T‐cell receptor (TCR) complex on CD4⁺ T cells during IFN‐γ stimulation abrogated the reduction in STAT1 activation in patients with RA but had no effect in HC. The phosphorylation of STAT1^S727 was similar in CD4⁺ T cells from patients with RA and HC. In contrast to CD4⁺ T cells, IFN‐γ–induced pSTAT1^Y701 levels in CD8⁺ T cells were equivalent or higher in patients with RA compared with HC. Total STAT1 levels (phosphorylated + unphosphorylated) were lower in CD4⁺ and CD8⁺ T cells from patients with RA compared with HC.

Conclusion

We report diminished IFN‐γ–induced pSTAT1^Y701 levels in CD4⁺ T cells in patients with RA, which were restored by TCR engagement. There were lower levels of total STAT1 in patients with RA compared with HC, but this likely does not explain diminished IFN‐γ–induced pSTAT1^Y701 levels in CD4⁺ T cells because activation in CD8⁺ T cells was higher or equivalent to that seen in HC. The enhanced IFNGR expression in patients with RA reported previously may reflect a compensatory mechanism to overcome deficiency in IFN‐γ responsiveness.

Atypical phenotype and response of B cells in patients with seropositive rheumatoid arthritis

Patients with rheumatoid arthritis (RA) may be classified as seropositive or seronegative according to the presence of autoantibodies. An abnormal B cell phenotype and function could be one of the main components of the immunopathology of seropositive patients; however, there is little information regarding B cell defects in these patients. This study shows a broad characterization of the B cell phenotype and function in patients with seropositive RA. We focused mainly on the evaluation of subsets, the expression of modulatory molecules of cell activation (CD22, FcɣRIIb and FcµR), calcium mobilization, global tyrosine phosphorylation, expression of activation markers, cytokine and immunoglobulin (Ig) production, proliferation and the in-vitro generation of plasma cells. Increased frequency of CD27^- IgM^- IgD^- and CD21^- B cells was observed in patients with seropositive RA compared with healthy donors (HD). Decreased expression of CD22 was primarily found in memory B cells of patients with RA regardless of seropositivity. B cells from seropositive patients exhibited normal proliferation, calcium mobilization kinetics and global tyrosine phosphorylation, but showed an increased frequency of CD86⁺ B cells compared with HD. B cells of seropositive patients secrete less interleukin-10 after in-vitro activation and showed a decreased frequency of plasma cell differentiation and IgM production compared with HD. Our data indicate that patients with seropositive RA have an increased frequency of atypical B cell populations previously associated with chronic activation and antigen exposure. This may result in the observed low responsiveness of these cells in vitro.

Increased Extracellular ATP in Plasma of Rheumatoid Arthritis Patients Activates CD8+T Cells

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disorder with genetic and environmental causes often linked with the disease etiology. A disrupted metabolism has often been a characteristic of RA and an altered metabolic state of immune cells has been associated with their phenotypic and functional changes. The energy in the form of ATP produced by the metabolically active cells may thus initiate a cascade of immune responses there by influencing the disease pathogenesis or progression.

AIM OF THE STUDY

Through this study we have focused on determining the role of ATP in etiology of RA and aberrant cellular functions.

METHODS

Blood samples of 80 healthy controls (HC) and 95 RA patients were screened for extracellular ATP concentration, transcriptome analyses, an inflammatory mediator and the results were statistically analysed.

RESULTS

In this study, ATP is shown to be excessive in the plasma of RA patients (453.5 ± 16.09% in RA vs. 233.9 ± 10.07% in HC, p <0.0001) and significantly increases with the disease severity. The abundant extracellular ATP could activate circulating cytotoxic CD8⁺T cells in RA patients to produce Granzyme B.

CONCLUSION

Plasma ATP is thus identified to have a significant potential in progression and prognosis of RA and may thus be studied further to design better therapeutic approaches for the disease.

Construction of CII-Specific CAR-T to Explore the Cytokine Cascades Between Cartilage-Reactive T Cells and Chondrocytes

Cytokine cascades exist in many autoimmune disorders which amplify and sustain the autoimmune process and lead to chronic inflammatory injury to the host tissues. Increasing evidence indicates that chondrocytes can interact with T cells, which may be a crucial event in inflammatory arthritis. To address the reciprocal influences of cartilage-reactive T cells and chondrocytes, we constructed cartilage-reactive T cells by developing a type II collagen-specific chimeric antigen receptor (CII-CAR). An in vitro co-culture model of CII-CAR-T cells and fresh cartilage was developed, in which CII-CAR-T displayed specific proliferative capacity and cytokine release against fresh cartilage samples, and chondrocytes could respond to CII-CAR-T cells by secreting IL-6. The proposed model will help us to explore the possible cytokine cascades between cartilage-reactive T cells and cartilage.

Methrotexate Treatment Inmunomodulates Abnormal Cytokine Expression by T CD4 Lymphocytes Present in DMARD-Naïve Rheumatoid Arthritis Patients

CD4⁺T-lymphocytes are relevant in the pathogenesis of rheumatoid arthritis (RA), however, their potential involvement in early RA remains elusive. Methotrexate (MTX) is a commonly used disease-modifying antirheumatic drug (DMARD), but its mechanism has not been fully established. In 47 new-onset DMARD-naïve RA patients, we investigated the pattern of IFNγ, IL-4 and IL-17A expression by naïve (T_N), central (T_CM), effector memory (T_EM) and effector (T_E) CD4⁺ subsets; their STAT-1, STAT-6 and STAT-3 transcription factors phosphorylation, and the circulating levels of IFNγ, IL-4 and IL-17. We also studied the RA patients after 3 and 6 months of MTX treatment and according their clinical response. CD4⁺T-lymphocyte subsets and cytokine expression were measured using flow cytometry. New-onset DMARD-naïve RA patients showed a significant expansion of IL-17A⁺, IFNγ⁺ and IL-17A⁺IFNγ⁺ CD4⁺T-lymphocyte subsets and increased intracellular STAT-1 and STAT-3 phosphorylation. Under basal conditions, nonresponder patients showed increased numbers of circulating IL-17A producing T_N and T_MC CD4⁺T-lymphocytes and IFNγ producing T_N, T_CM, T_EM CD4⁺T-lymphocytes with respect to responders. After 6 months, the numbers of CD4⁺IL-17A⁺T_N remained significantly increased in nonresponders. In conclusion, CD4⁺T-lymphocytes in new-onset DMARD-naïve RA patients show IL-17A and IFNγ abnormalities in T_N, indicating their relevant role in early disease pathogenesis. Different patterns of CD4⁺ modulation are identified in MTX responders and nonresponders.

Anti-Citrullinated Protein Antibodies in Patients with Rheumatoid Arthritis: Biological Effects and Mechanisms of Immunopathogenesis

Individuals with high anti-citrullinated protein antibody (ACPA) titers have an increased risk of developing rheumatoid arthritis (RA). Although our knowledge of the generation and production of ACPAs has continuously advanced during the past decade, our understanding on the pathogenic mechanisms of how ACPAs interact with immune cells to trigger articular inflammation is relatively limited. Citrullination disorders drive the generation and maintenance of ACPAs, with profound clinical significance in patients with RA. The loss of tolerance to citrullinated proteins, however, is essential for ACPAs to exert their pathogenicity. N-linked glycosylation, cross-reactivity and the structural interactions of ACPAs with their citrullinated antigens further direct their biological functions. Although questions remain in the pathogenicity of ACPAs acting as agonists for a receptor-mediated response, immune complex (IC) formation, complement system activation, crystallizable fragment gamma receptor (FcγR) activation, cross-reactivity to joint cartilage and neutrophil extracellular trap (NET)-related mechanisms have all been suggested recently. This paper presents a critical review of the characteristics and possible biological effects and mechanisms of the immunopathogenesis of ACPAs in patients with RA.

Regulatory T cells in patients with early untreated rheumatoid arthritis: Phenotypic changes in the course of methotrexate treatment

Rheumatoid arthritis (RA) is frequent systemic autoimmune disease characterized by excessive activation of collagen-specific T helper cells, and elevated level of autoantibodies in the serum. Development of RA is associated with defect in compartment of regulatory CD4+Foxp3+ T cells (Treg), but data concerning suppressive potential of Treg population in RA patients are contradictory and depend on the stage of disease. In this study we aimed to characterize abundance and phenotypic markers of CD4+Foxp3+ Treg in peripheral blood of healthy donors compared to untreated early RA patients to find potential correlations with the disease activity, antibody level, and absolute numbers and proportion of different subpopulations of T cells. Moreover, we assessed the influence of methotrexate (MT) treatment on percentage and absolute numbers of CD4+Foxp3+ Treg from the peripheral blood of untreated early RA patients. We demonstrate that increase and phenotypic changes in Treg population correlate well with response to MT. Analysis of the cohorts of matched RA patients (n = 45) and healthy controls (n = 20) revealed that patients with untreated early RA demonstrate substantial decrease in blood Treg percentage and absolute number, as well as low level of activated Treg surface markers in comparison to healthy control. The defect in Treg compartment negatively correlates with both RA activity and antibody level. MT treatment of patients with early untreated RA increases both proportion and absolute number of Treg with high level of activation markers, suggesting an increase of their functional capacity. Here we speculate the role of Tregs as specific cellular marker of successful RA treatment.

Reporters of TCR signaling identify arthritogenic T cells in murine and human autoimmune arthritis

How arthritis-causing T cells trigger rheumatoid arthritis (RA) is not understood since it is difficult to differentiate T cells activated by inflammation in arthritic joints from those activated through their T cell antigen receptor (TCR) by self-antigens. We developed a model to identify and study antigen-specific T cell responses in arthritis. Nur77—a specific marker of TCR signaling—was used to identify antigen-activated T cells in the SKG arthritis model and in patients with RA. Nur77 could distinguish highly arthritogenic and autoreactive T cells in SKG mice. The enhanced autoreactivity was associated with increased interleukin-6 (IL-6) receptor signaling, likely contributing to their arthritogenicity. These data highlight a functional correlate between Nur77 expression, arthritogenic T cell populations, and heightened IL-6 sensitivity in SKG mice with translatable implications for human RA.

How pathogenic cluster of differentiation 4 (CD4) T cells in rheumatoid arthritis (RA) develop remains poorly understood. We used Nur77—a marker of T cell antigen receptor (TCR) signaling—to identify antigen-activated CD4 T cells in the SKG mouse model of autoimmune arthritis and in patients with RA. Using a fluorescent reporter of Nur77 expression in SKG mice, we found that higher levels of Nur77-eGFP in SKG CD4 T cells marked their autoreactivity, arthritogenic potential, and ability to more readily differentiate into interleukin-17 (IL-17)–producing cells. The T cells with increased autoreactivity, nonetheless had diminished ex vivo inducible TCR signaling, perhaps reflective of adaptive inhibitory mechanisms induced by chronic autoantigen exposure in vivo. The enhanced autoreactivity was associated with up-regulation of IL-6 cytokine signaling machinery, which might be attributable, in part, to a reduced amount of expression of suppressor of cytokine signaling 3 (SOCS3)—a key negative regulator of IL-6 signaling. As a result, the more autoreactive GFP^hi CD4 T cells from SKGNur mice were hyperresponsive to IL-6 receptor signaling. Consistent with findings from SKGNur mice, SOCS3 expression was similarly down-regulated in RA synovium. This suggests that despite impaired TCR signaling, autoreactive T cells exposed to chronic antigen stimulation exhibit heightened sensitivity to IL-6, which contributes to the arthritogenicity in SKG mice, and perhaps in patients with RA.

The Abnormal CD4+T Lymphocyte Subset Distribution and Vbeta Repertoire in New-onset Rheumatoid Arthritis Can Be Modulated by Methotrexate Treament

Patients with long-term, treated, rheumatoid arthritis (RA) show abnormalities in their circulating CD4+ T-lymphocytes, but whether this occurs in recently diagnosed naïve patients to disease-modifying drugs (DMARDs) is under discussion. These patients show heterogeneous clinical response to methotrexate (MTX) treatment. We have examined the count of circulating CD4+ T-lymphocytes, and their naïve (T_N), central memory (T_CM), effector memory (T_EM) and effector (T_E) subsets, CD28 expression and Vβ TCR repertoire distribution by polychromatic flow cytometry in a population of 68 DMARD-naïve recently diagnosed RA patients, before and after 3 and 6 months of MTX treatment. At pre-treatment baseline, patients showed an expansion of the counts of CD4+ T_N, T_EM, T_E and T_CM lymphocyte subsets, and of total CD4+CD28− cells and of the T_E subset with a different pattern of numbers in MTX responder and non-responders. The expansion of CD4+T_EM lymphocytes showed a predictive value of MTX non-response_. MTX treatment was associated to different modifications in the counts of the CD4+ subsets and of the Vβ TCR repertoire family distribution and in the level of CD28 expression in responders and non-responders. In conclusion, the disturbance of CD4+ lymphocytes is already found in DMARD-naïve RA patients with different patterns of alterations in MTX responders and non-responders.

The Number of Regulatory B Cells is Increased in Mice with Collagen-induced Arthritis

The aim of this study is to investigate changes in regulatory B cells (Bregs) and the expression of related cytokines such as interleukin-10 (IL-10) and transforming growth factor (TGF)-β in a mouse model of collagen-induced arthritis (CIA). A total 20 DBA/1 mice (6-8 weeks old) were randomly divided into control and CIA disease groups. For the CIA disease group, animals were injected intradermally with chicken collagen type II and complete Freund's adjuvant. The calculated arthritis index score of the CIA group was significantly higher than that in control group. Hematoxylin and eosin staining showed tumid synovial cells with irregular arrangement and obvious hyperplasia, with a high degree of inflammatory cell infiltration in CIA model group. Cytometric bead array technology and quantitative RT-PCR indicated that the levels of IL-10 and TGF-β in serum, and synovial cells were significantly increased in the CIA group. The proportion of Bregs in the spleen of the CIA group was significantly increased compared to the control group. In conclusion, our findings demonstrate that the number of Bregs and the expression of TGF-β and IL-10 are enhanced in mice with CIA.

Genetic variants differentially associated with rheumatoid arthritis and systemic lupus erythematosus reveal the disease-specific biology

Two rheumatic autoimmune diseases, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), have distinct clinical features despite their genetic similarities. We hypothesized that disease-specific variants exclusively associated with only one disease could contribute to disease-specific phenotypes. We calculated the strength of disease specificity for each variant in each disease against the other disease using summary association statistics reported in the largest genome-wide association studies of RA and SLE. Most of highly disease-specific associations were explained by non-coding variants that were significantly enriched within regulatory regions (enhancers or H3K4me3 histone modification marks) in specific cell or organ types. (e.g., In RA, regulatory T primary cells, CD4+ memory T primary cells, thymus and lung; In SLE, CD19+ B primary cells, mobilized CD34+ primary cells, regulatory T primary cells and monocytes). Consistently, genes in the disease-specific loci were significantly involved in T cell- and B cell-related gene sets in RA and SLE. In summary, this study identified disease-specific variants between RA and SLE, and provided statistical evidence for disease-specific cell types, organ and gene sets that may drive the disease-specific phenotypes.

KCa1.1 and Kv1.3 channels regulate the interactions between fibroblast-like synoviocytes and T lymphocytes during rheumatoid arthritis

BACKGROUND

Fibroblast-like synoviocytes (FLS) and CCR7- effector memory T (TEM) cells are two of the major cell types implicated in the progression of rheumatoid arthritis (RA). In particular, FLS become highly invasive, whereas TEM cells proliferate and secrete proinflammatory cytokines, during RA. FLS and T cells may also interact and influence each other's phenotypes. Inhibition of the pathogenic phenotypes of both FLS and TEM cells can be accomplished by selectively blocking the predominant potassium channels that they upregulate during RA: KCa1.1 (BK, Slo1, MaxiK, KCNMA1) upregulated by FLS and Kv1.3 (KCNA3) upregulated by activated TEM cells. In this study, we investigated the roles of KCa1.1 and Kv1.3 in regulating the interactions between FLS and TEM cells and determined if combination therapies of KCa1.1- and Kv1.3-selective blockers are more efficacious than monotherapies in ameliorating disease in rat models of RA.

METHODS

We used in vitro functional assays to assess the effects of selective KCa1.1 and Kv1.3 channel inhibitors on the interactions of FLS isolated from rats with collagen-induced arthritis (CIA) with syngeneic TEM cells. We also used flow cytometric analyses to determine the effects of KCa1.1 blockers on the expression of proteins used for antigen presentation on CIA-FLS. Finally, we used the CIA and pristane-induced arthritis models to determine the efficacy of combinatorial therapies of KCa1.1 and Kv1.3 blockers in reducing disease severity compared with monotherapies.

RESULTS

We show that the interactions of FLS from rats with CIA and of rat TEM cells are regulated by KCa1.1 and Kv1.3. Inhibiting KCa1.1 on FLS reduces the ability of FLS to stimulate TEM cell proliferation and migration, and inhibiting Kv1.3 on TEM cells reduces TEM cells' ability to enhance FLS expression of KCa1.1 and major histocompatibility complex class II protein, as well as stimulates their invasion. Furthermore, we show that combination therapies of selective KCa1.1 and Kv1.3 blockers are more efficacious than monotherapies at reducing signs of disease in two rat models of RA.

CONCLUSIONS

Our results demonstrate the importance of KCa1.1 and Kv1.3 in regulating FLS and TEM cells during RA, as well as the value of combined therapies targeting both of these cell types to treat RA.

Functional and phenotypic heterogeneity of Th17 cells in health and disease

BACKGROUND

Th17 cells have nonredundant roles in maintaining immunity, particularly at mucosal surfaces. These roles are achieved principally through the production of cytokines and the recruitment of other immune cells to maintain the integrity of mucosal barriers and prevent the dissemination of microorganisms. Th17 cells are heterogeneous and exhibit a considerable degree of plasticity. This allows these cells to respond to changing environmental challenges. However, Th17 cells also play pro-inflammatory roles in chronic autoimmune diseases. The trigger(s) that initiate these Th17 responses in chronic autoimmune diseases remain unclear.

DESIGN

In this report, we provide an overview of studies involving animal models, patient data, genome wide association studies and clinical trials targeting IL-17 for treatment of patients to gain a better understanding of the pathogenic roles of Th17 cells play in a range of autoimmune diseases.

RESULTS

The report sheds light on likely triggers that initiate or perpetuate Th17 responses that promote chronic inflammation and autoimmunity. The divergent effects of tumour necrosis factor alpha blockade on Th17 cells in patients, is explored. Furthermore, we highlight the role of Th17 cells in inducing autoreactive B cells, leading to autoantibody production. Pathogenic bacterial species can change Th17 cell phenotype and responses. These findings provide insights into how Th17 cells could be induced to promoting autoimmune disease pathogenesis.

CONCLUSION

This article provides an overview of the distinct roles Th17 cells play in maintaining immunity at mucosal surfaces and in skin mucosa and how their functional flexibility could be linked with chronic inflammation in autoimmune rheumatic diseases.

Dihydromyricetin Inhibits Inflammation of Fibroblast-Like Synoviocytes through Regulation of Nuclear Factor-κB Signaling in Rats with Collagen-Induced Arthritis

Dihydromyricetin (DMY), the main flavonoid of Ampelopsis grossedentata, has potent anti-inflammatory activity. However, the effect of DMY on chronic autoimmune arthritis remains undefined. In this study, we investigated the therapeutic effects of DMY on collagen-induced arthritis (CIA). Wistar rats were immunized with bovine type II collagen to establish CIA and were then administered DMY intraperitoneally (5, 25, and 50 mg/kg) every other day for 5 weeks. Paw swelling, clinical scoring, and histologic analysis were assessed to determine the therapeutic effects of DMY on the development of arthritis in CIA rats. The results showed that treatment with DMY significantly reduced erythema and swelling in the paws of CIA rats. Pathologic analysis of the knee joints and peripheral blood cytokine assay results confirmed the antiarthritic effects of DMY on synovitis and inflammation. Fibroblast-like synoviocytes (FLSs) were isolated from the synovium of CIA rats and treated with 10 ng/ml interleukin (IL)-1β DMY significantly inhibited the proliferation, migration, and inflammation of IL-1β-induced FLSs, whereas it significantly increased IL-1β-induced FLS apoptosis in a dose-dependent manner (6.25-25 μM). Moreover, DMY suppressed phosphorylation of IκB kinase (IKK) and inhibitor of NF-κB α and subsequently reduced the IL-1β-induced nucleus translocation of NF-κB in FLSs. Through a molecular docking assay, we demonstrated that DMY could directly bind to the Thr9 and Asp88 residues in IKKα and the Asp95, Asn142, and Gln167 residues in IKKβ These findings demonstrate that DMY could alleviate inflammation in CIA rats and attenuate IL-1β-induced activities in FLSs through suppression of NF-κB signaling.

Gene-Based Nonparametric Testing of Interactions Using Distance Correlation Coefficient in Case-Control Association Studies

Among the various statistical methods for identifying gene⁻gene interactions in qualitative genome-wide association studies (GWAS), gene-based methods have recently grown in popularity because they confer advantages in both statistical power and biological interpretability. However, most of these methods make strong assumptions about the form of the relationship between traits and single-nucleotide polymorphisms, which result in limited statistical power. In this paper, we propose a gene-based method based on the distance correlation coefficient called gene-based gene-gene interaction via distance correlation coefficient (GBDcor). The distance correlation (dCor) is a measurement of the dependency between two random vectors with arbitrary, and not necessarily equal, dimensions. We used the difference in dCor in case and control datasets as an indicator of gene⁻gene interaction, which was based on the assumption that the joint distribution of two genes in case subjects and in control subjects should not be significantly different if the two genes do not interact. We designed a permutation-based statistical test to evaluate the difference between dCor in cases and controls for a pair of genes, and we provided the p-value for the statistic to represent the significance of the interaction between the two genes. In experiments with both simulated and real-world data, our method outperformed previous approaches in detecting interactions accurately.

Amelioration of clinical symptoms of patients with refractory rheumatoid arthritis following treatment with autologous bone marrow-derived mesenchymal stem cells: A successful clinical trial in Iran

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune arthropathy characterized by synovial hyperplasia leading to functional impairment. Although the exact cause of RA is unknown, there is evidence suggesting the role of T cell subtypes in the pathogenesis of RA. Conventional therapy in some RA patients is associated with mild or severe side effects, and resistance of some patients has been reported to these types of therapy. The therapeutic potential of mesenchymal stem cells (MSCs) introduced them as a novel therapeutic choice for the treatment of rheumatic diseases. The aim of our study was to evaluate the effects of intravenous administration of autologous bone marrow-derived MSCs on the immunological, clinical and para-clinical factors such as regulatory T cells, Th17 cells, CD8+ T cells, CD4+ T cells, disease activity score 28-erythrocyte sedimentation rate (DAS28-ESR), visual analogue scale (VAS), ESR, C-reactive protein (CRP), rheumatoid factor (RF), and anti-cyclic citrullinated peptide (anti-CCP) antibodies in patients with refractory RA. Nine refractory RA patients with no other rheumatologic disorders were included in this study. All patients received a single intravenous dose of 1 × 10⁶ autologous bone marrow-derived MSCs/kg, and were followed up at 1, 6 and 12 months after injection of MSCs. We found a significant decreasing trend in Th17 percentage and geometric mean fluorescence intensity for IL-17A following injection of MSCs at 12 months compared to the time point zero. Furthermore, a significant increase in regulatory T cells percentage was observed at the end of the first month after the intervention. DAS28-ESR decreased significantly at 1 and 12 months after MSC therapy. VAS score showed a significant decreasing trend during the follow-up periods. No significant difference was found for serum CRP and anti-CCP levels after the intervention. In conclusion, our data indicated that clinical symptoms were significantly ameliorated following the intravenous injection of autologous bone marrow-derived MSCs to the patients with refractory RA.

Pathogenic Role of Immune Cells in Rheumatoid Arthritis: Implications in Clinical Treatment and Biomarker Development

Rheumatoid arthritis (RA) is a chronic, autoimmune, systemic, inflammatory disorder that affects synovial joints, both small and large joints, in a symmetric pattern. This disorder usually does not directly cause death but significantly reduces the quality of life and life expectancy of patients if left untreated. There is no cure for RA but, patients are usually on long-term disease modifying anti-rheumatic drugs (DMARDs) to suppress the joint inflammation, to minimize joint damage, to preserve joint function, and to keep the disease in remission. RA is strongly associated with various immune cells and each of the cell type contributes differently to the disease pathogenesis. Several types of immunomodulatory molecules mainly cytokines secreted from immune cells mediate pathogenesis of RA, hence complicating the disease treatment and management. There are various treatments for RA depending on the severity of the disease and more importantly, the patient’s response towards the given drugs. Early diagnosis of RA and treatment with (DMARDs) are known to significantly improve the treatment outcome of patients. Sensitive biomarkers are crucial in early detection of disease as well as to monitor the disease activity and progress. This review aims to discuss the pathogenic role of various immune cells and immunological molecules in RA. This review also highlights the importance of understanding the immune cells in treating RA and in exploring novel biomarkers.

The combination of FK506 and an anti-CD147 mAb exerts potential therapeutic effects on a mouse model of collagen-induced arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease, and excessive T lymphocyte activation plays a critical role in the development of inflammation. CD147 is an antigen related to T cell activation, CD147 blockade exerts beneficial effects on RA. FK506, also known as tacrolimus, exerts strong immunosuppressive effects by inhibiting T cell activation. In this study, RL73 (an anti-mouse CD147 functional-grade purified antibody) and FK506 were co-administered to mice with collagen-induced arthritis (CIA). As expected, the combination of these two drugs produced superior therapeutic effects than either drug alone and enabled the administration of each drug at a lower dose. Moreover, joint damage and destruction were significantly improved in mice injected with both FK506 and RL73 compared with mice injected with either agent alone. These effects might have been observed because the proportions of CD4 + T and CD8 + T cells in the mouse spleen of the combination regimen were clearly decreased compared with each monotherapy. In addition, the proportions of Th2 subsets in the mouse spleen and peripheral blood were clearly increased, and the serum levels of the cytokines interleukin 4 (IL-4) and IL-10 were markedly increased in mice treated with the combination therapy compared with the other groups of mice. The splenic total number of T lymphocytes also showed that the inhibition of T lymphocytes was the most obvious in the combined treatment group. Based on the results from the present study, combining FK506 and the anti-CD147 mAb might be a new practical therapeutic option for the treatment of RA.

Signal Transducer and Activator of Transcription 3 Hyperactivation Associates With Follicular Helper T Cell Differentiation and Disease Activity in Rheumatoid Arthritis

Follicular helper T (Tfh) cells are the specialized CD4⁺ T cell subset that supports B cells to produce high-affinity antibodies and generate humoral memory. Not only is the function of Tfh cells instrumental to mount protect antibodies but also to support autoantibody production and promote systemic inflammation in autoimmune diseases. However, it remains unclear how the activation of Tfh cells is driven in autoimmune diseases. Here, we report that in patients with rheumatoid arthritis (RA), excessive generation of CXCR5⁺PD-1⁺ memory Tfh cells was observed and the frequency of memory Tfh cells correlated with disease activity score calculator for RA (DAS28). The differentiation of Tfh cells is dependent on signal transducer and activator of transcription 3 (STAT3), the key transcription factor downstream of cytokine signal pathways. A drastic increase of phosphorylated STAT3 (pSTAT3) in CD4⁺ T cells were detected in RA patients who also produced larger amounts of STAT3-stimulating cytokines, including IL-6, IL-21, IL-10, and leptin than those of healthy controls. Importantly, the phosphorylation status of STAT3 in CD4⁺ T cells positively correlated with the plasma concentration of IL-6 and the frequency of memory Tfh cells. This study reveals an IL-6-pSTAT3-Tfh immunoregulatory axis in the pathogenesis of RA and reinforces its candidature as biomarkers and targets for diagnosis and therapy.

In Vivo PET Imaging of the Activated Immune Environment in a Small Animal Model of Inflammatory Arthritis

BACKGROUND

Evolving immune-mediated therapeutic strategies for rheumatoid arthritis (RA) may benefit from an improved understanding of the complex role that T-cell activation plays in RA. This study assessed the potential of fluorine-18-labeled 9-β-d-arabinofuranosylguanine ([¹⁸F]F-AraG) positron emission tomography (PET) imaging to report immune activation in vivo in an adjuvant-induced arthritis (AIA) small animal model.

METHODS

Using positron emission tomography-computed tomography imaging, uptake of [¹⁸F]F-AraG in the paws of mice affected by arthritis at 6 (acute) and 20 (chronic) days following AIA induction in a single paw was assessed and compared to uptake in contralateral control paws. Fractions of T cells and B cells demonstrating markers of activation at the 2 time points were determined by flow cytometry.

RESULTS

Differential uptake of [¹⁸F]F-AraG was demonstrated on imaging of the affected joint when compared to control at both acute and chronic time points with corresponding changes in markers of T-cell activation observed on flow cytometry.

CONCLUSION

[¹⁸F]F-AraG may serve as an imaging biomarker of T-cell activation in inflammatory arthritis. Further development of this technique is warranted and could offer a tool to explore the temporal link between activated T cells and RA as well as to monitor immune-mediated therapies for RA in clinical trials.

Reversibility of peripheral blood leukocyte phenotypic and functional changes after exposure to and withdrawal from tofacitinib, a Janus kinase inhibitor, in healthy volunteers

This study evaluated the short-term effects of tofacitinib treatment on peripheral blood leukocyte phenotype and function, and the reversibility of any such effects following treatment withdrawal in healthy volunteers. Cytomegalovirus (CMV)-seropositive subjects received oral tofacitinib 10 mg twice daily for 4 weeks and were followed for 4 weeks after drug withdrawal. There were slight increases in total lymphocyte and total T-cell counts during tofacitinib treatment, and B-cell counts increased by up to 26%. There were no significant changes in granulocyte or monocyte counts, or granulocyte function. Naïve and central memory T-cell counts increased during treatment, while all subsets of activated T cells were decreased by up to 69%. T-cell subsets other than effector memory cluster of differentiation (CD)4+, activated naïve CD4+ and effector CD8+ T-cell counts and B-cell counts, normalized 4 weeks after withdrawal. Following ex vivo activation, measures of CMV-specific T-cell responses, and antigen non-specific T-cell-mediated cytotoxicity and interferon (IFN)-γ production, decreased slightly. These T-cell functional changes were most pronounced at Day 15, partially normalized while still on tofacitinib and returned to baseline after drug withdrawal. Total natural killer (NK)-cell counts decreased by 33%, returning towards baseline after drug withdrawal. NK-cell function decreased during tofacitinib treatment, but without a consistent time course across measured parameters. However, markers of NK-cell-mediated cytotoxicity, antibody-dependent cellular cytotoxicity and IFN-γ production were decreased up to 42% 1 month after drug withdrawal. CMV DNA was not detectable in whole blood, and there were no cases of herpes zoster reactivation. No new safety concerns arose. In conclusion, the effect of short-term tofacitinib treatment on leukocyte composition and function in healthy CMV+ volunteers is modest and largely reversible 4 weeks after withdrawal.