Mechanistic immunological based classification of rheumatoid arthritis

Helicobacter pylori and rheumatoid arthritis: Investigation of relation from traditional Chinese medicine

Rheumatoid arthritis (RA) is an autoimmune condition that predominantly affects synovial joints, manifesting with joint swelling, pain, and stiffness. In advanced stages, unchecked inflammation can inflict damage on bone and cartilage, resulting in disabilities and deformities of the joints. Additionally, systemic and extra-articular complications may arise due to the consequences of uncontrolled inflammation. Helicobacter pylori (H. pylori) is one of the most prevalent chronic bacterial infections in humans. This microorganism is a spiral-shaped, flagellated, microaerophilic gram-negative bacterium. Prolonged exposure leads to the activation of the immune system, with infected gastric mucosa epithelial cells continuously producing cytokines. This production, in turn, triggers the generation of antibodies as well as T Helper 1 and T Helper 2 effector T cells. The persistent antigenic stimulation resulting from H. pylori infection could lead to the progression of autoimmune diseases. Numerous clinical and pharmacological trials have illustrated the efficacy of traditional Chinese medicine against H. pylori. This review aims to delve into the connection between H. pylori and rheumatoid arthritis so as understand the pathogenesis. The concluding section of this review explores the interplay of Chinese medicine and Helicobacter pylori concerning rheumatoid arthritis.

Genome-Wide Aggregated Trans Effects Analysis Identifies Genes Encoding Immune Checkpoints as Core Genes for Rheumatoid Arthritis

OBJECTIVE

The sparse effector "omnigenic" hypothesis postulates that the polygenic effects of common single nucleotide polymorphisms (SNPs) on a typical complex trait are mediated by trans effects that coalesce on expression of a relatively sparse set of core genes. The objective of this study was to identify core genes for rheumatoid arthritis by testing for association of rheumatoid arthritis with genome-wide aggregated trans effects (GATE) scores for expression of each gene as transcript in whole blood or as circulating protein levels.

METHODS

GATE scores were calculated for 5,400 cases and 453,705 non-cases of primary rheumatoid arthritis in UK Biobank participants of European ancestry.

RESULTS

Testing for association with GATE scores identified 16 putative core genes for rheumatoid arthritis outside the HLA region, of which six-TP53BP1, PDCD1, TNFRSF14, LAIR1, LILRA4, and IDO1-were supported by Mendelian randomization analysis based on the marginal likelihood of the causal effect parameter. Five of these 16 genes were validated by a reported association of rheumatoid arthritis with SNPs within 200 kb of the transcription site, eight by association of the measured protein level with rheumatoid arthritis in UK Biobank, 10 by experimental perturbation in mouse models of inflammatory arthritis, and two-CTLA4 and PDCD1-by evidence that drugs targeting the gene cause or ameliorate inflammatory arthritis in humans. Fourteen of these 16 genes are in pathways affecting immunity or inflammation, and six-CD5, CTLA4, TIGIT, LAIR1, TNFRSF14, and PDCD1-encode receptors that have been characterized as immune checkpoints exploited by cancer cells to escape the immune response.

CONCLUSION

These results highlight the key role of immune checkpoints in rheumatoid arthritis and identify possible therapeutic targets.

New insight in treating autoimmune diseases by targeting autophagy

Autophagy is a highly conserved biological process in eukaryotes, which degrades cellular misfolded proteins, damaged organelles and invasive pathogens in the lysosome-dependent manner. Autoimmune diseases caused by genetic elements, environments and aberrant immune responses severely impact patients' living quality and even threaten life. Recently, numerous studies have reported autophagy can regulate immune responses, and play an important role in autoimmune diseases. In this review, we summarised the features of autophagy and autophagy-related genes, enumerated some autophagy-related genes involved in autoimmune diseases, and further overviewed how to treat autoimmune diseases through targeting autophagy. Finally, we outlooked the prospect of relieving and curing autoimmune diseases by targeting autophagy pathway.

How underappreciated autoinflammatory (innate immunity) mechanisms dominate disparate autoimmune disorders

Historically inflammation against self was considered autoimmune which stems back to the seminal observations by Ehrlich who described serum factors, now known to be autoantibodies produced by B lineage cells that mediate "horror autotoxicus". The 20th century elucidation of B- and T-cell adaptive immune responses cemented the understanding of the key role of adaptive immune responses in mediating pathology against self. However, Mechnikov shared the Nobel Prize for the discovery of phagocytosis, the most rudimentary aspect of innate immunity. Fast forward some 100 years and an immunogenetic understanding of innate immunity led to the categorising of innate immunopathology under the umbrella term 'auto inflammation' and terminology such as "horror autoinflammaticus" to highlight the schism from the classical adaptive immune understanding of autoimmunity. These concepts lead to calls for a two-tiered classification of inflammation against self, but just as innate and adaptive immunity are functionally integrated, so is immunopathology in many settings and the concept of an autoimmune to autoinflammation continuum emerged with overlaps between both. Herein we describe several historically designated disorders of adaptive immunity where innate immunity is key, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD) where the immunopathology phenotype is strongly linked to major histocompatibility complex (MHC) class II associations and responds to drugs that target T-cells. We also consider MHC-I-opathies including psoriasis and Behcet's disease(BD) that are increasingly viewed as archetype CD8 T-cell related disorders. We also briefly review the key role of barrier dysfunction in eczema and ulcerative colitis (UC) where innate tissue permeability barrier dysfunction and microbial dysbiosis contributes to prominent adaptive immune pathological mechanisms. We also highlight the emerging roles of intermediate populations of lymphocytes including gamma delta (γδ) and mucosal-associated invariant T (MAIT) cells that represent a blend of adaptive immune plasticity and innate immune rapid responders that may also determine site specific patterns of inflammation.

Effects of smoking on clinical treatment outcomes amongst patients with chronic inflammatory diseases initiating biologics: secondary analyses of the prospective BELIEVE cohort study

The prevalence and disease burden of chronic inflammatory diseases (CIDs) are predicted to rise. Patients are commonly treated with biological agents, but the individual treatment responses vary, warranting further research into optimizing treatment strategies. This study aimed to compare the clinical treatment responses in patients with CIDs initiating biologic therapy based on smoking status, a notorious risk factor in CIDs. In this multicentre cohort study including 233 patients with a diagnosis of Crohn's disease, ulcerative colitis, rheumatoid arthritis, axial spondyloarthritis, psoriatic arthritis or psoriasis initiating biologic therapy, we compared treatment response rates after 14 to 16 weeks and secondary outcomes between smokers and non-smokers. We evaluated the contrast between groups using logistic regression models: (i) a "crude" model, only adjusted for the CID type, and (ii) an adjusted model (including sex and age). Among the 205 patients eligible for this study, 53 (26%) were smokers. The treatment response rate among smokers (n = 23 [43%]) was lower compared to the non-smoking CID population (n = 92 [61%]), corresponding to a "crude" OR of 0.51 (95% CI: [0.26;1.01]) while adjusting for sex and age resulted in consistent findings: 0.51 [0.26;1.02]. The contrast was apparently most prominent among the 38 RA patients, with significantly lower treatment response rates for smokers in both the "crude" and adjusted models (adjusted OR 0.13, [0.02;0.81]). Despite a significant risk of residual confounding, patients with CIDs (rheumatoid arthritis in particular) should be informed that smoking probably lowers the odds of responding sufficiently to biological therapy. Registration: Clinical.Trials.gov NCT03173144.

Advances in local drug delivery technologies for improved rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by an inflammatory microenvironment and cartilage erosion within the joint cavity. Currently, antirheumatic agents yield significant outcomes in RA treatment. However, their systemic administration is limited by inadequate drug retention in lesion areas and non-specific tissue distribution, reducing efficacy and increasing risks such as infection due to systemic immunosuppression. Development in local drug delivery technologies, such as nanostructure-based and scaffold-assisted delivery platforms, facilitate enhanced drug accumulation at the target site, controlled drug release, extended duration of the drug action, reduced both dosage and administration frequency, and ultimately improve therapeutic outcomes with minimized damage to healthy tissues. In this review, we introduced pathogenesis and clinically used therapeutic agents for RA, comprehensively summarized locally administered nanostructure-based and scaffold-assisted drug delivery systems, aiming at improving the therapeutic efficiency of RA by alleviating the inflammatory response, preventing bone erosion and promoting cartilage regeneration. In addition, the challenges and future prospects of local delivery for clinical translation in RA are discussed.

Synovial and serum B cell signature of autoantibody-negative rheumatoid arthritis vs autoantibody-positive rheumatoid arthritis and psoriatic arthritis

OBJECTIVES

Autoantibody-negative RA differs from autoantibody-positive RA in several clinical aspects, possibly underpinned by pathogenetic differences. At present, the role of adaptive immune responses in autoantibody-negative RA remains unclear. Here, we investigated the synovial and serum immunophenotype indicative of B lymphocyte involvement across the spectrum of autoantibody-positive and -negative chronic arthritides.

METHODS

Ultrasound-guided synovial biopsies were retrieved from 131 patients: 43 autoantibody-positive RA, 35 autoantibody-negative RA, 25 polyarticular PsA and 28 oligoarticular PsA. Samples were analysed for the degree of histological inflammation, B lymphocyte infiltration and the distribution of different pathotypes (lympho-myeloid, myeloid, pauci-immune). Serum levels of the B cell chemoattractant CXCL13 were compared among groups.

RESULTS

Synovitis scores and CD68+ sublining macrophage infiltration were comparable irrespective of clinical diagnosis and disease subtype. In contrast, the degree of B lymphocyte infiltration and the frequency of lympho-myeloid synovitis in autoantibody-negative RA were lower than those of autoantibody-positive RA (mean [s.d.] 1.8 [1] vs 2.4 [0.6], P = 0.03, and 38.2% vs 62.9%, P = 0.07, respectively), and similar to polyarticular PsA. Oligoarticular PsA had the lowest B cell scores. Serum CXCL13 was associated with lympho-myeloid synovitis and followed a similar gradient, with the highest levels in autoantibody-positive RA, intermediate and comparable levels in autoantibody-negative RA and polyarticular PsA, and low levels in oligoarticular PsA.

CONCLUSIONS

The synovial and serum immunophenotype indicative of B lymphocyte involvement in autoantibody-negative RA differs from that of autoantibody-positive RA and more closely resembles that observed in polyarticular PsA. The pathobiological stratification of chronic inflammatory arthritides beyond clinical diagnosis may fuel personalized treatment strategies.

Start RA treatment - Biologics or JAK-inhibitors?

Janus Kinase inhibitors (JAKi) have been approved for the treatment of Rheumatoid Arthritis (RA) for several years. They are the first oral advanced treatment with efficacy similar to, if not greater than, biologic agents. Recently, concerns over their safety was raised by the results from Oral Surveillance trial suggesting that tofacitinib, one of the JAKi, was associated with higher cardiovascular adverse events and malignancies than TNF inhibitors (TNFi). Since then, regulatory authorities have added warnings to the labels of JAKi. On this purpose, whether rheumatologists should use JAKi as first line advance treatment has become a controversial topic. Some rheumatologists have argued that biologics should be first line advance treatment since there are extensive effectiveness and safety data. In addition, with the advent of biosimilar drugs, they are the most cost-effective treatment. On the other hand, JAKi are very efficacious and are generally safe apart from older and high-risk patients. When TNFi are contraindicated and in certain RA patients ,especially when an oral drug is preferable, JAKi have significant advantage providing patients are involved in the decision-making process.

Autoantibody-negative rheumatoid arthritis: still a challenge for the rheumatologist

Increased research over the past 30 years has greatly improved the understanding of the pathophysiological mechanisms and clinical aspects of autoantibody-positive rheumatoid arthritis, resulting in improved management and outcomes. In contrast, the subset of rheumatoid arthritis that does not have autoantibodies (such as rheumatoid factor and anti-citrullinated protein autoantibodies) remains less well defined in its pathogenic mechanisms. Autoantibody-negative rheumatoid arthritis continues to pose diagnostic challenges, might respond differently to therapies, and appears to be burdened with different comorbidities and outcomes. The clear separation of rheumatoid arthritis according to serotypes is still a subject of uncertainty and controversy, and studies specifically focused on comparing rheumatoid arthritis and rheumatoid arthritis-like arthritides that do not have autoantibodies remain scarce. The purpose of this Review is to summarise the peculiarities that make autoantibody-negative rheumatoid arthritis different from its autoantibody-positive counterpart, with the aim of generating debate and stimulating further research on this challenging condition.

Rheumatoid arthritis: the old issue, the new therapeutic approach

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease of unknown etiology. The most common form of this disease is chronic inflammatory arthritis, which begins with inflammation of the synovial membrane of the affected joints and eventually leads to disability of the affected limb. Despite significant advances in RA pharmaceutical therapies and the availability of a variety of medicines on the market, none of the available medicinal therapies has been able to completely cure the disease. In addition, a significant percentage (30-40%) of patients do not respond appropriately to any of the available medicines. Recently, mesenchymal stromal cells (MSCs) have shown promising results in controlling inflammatory and autoimmune diseases, including RA. Experimental studies and clinical trials have demonstrated the high power of MSCs in modulating the immune system. In this article, we first examine the mechanism of RA disease, the role of cytokines and existing medicinal therapies. We then discuss the immunomodulatory function of MSCs from different perspectives. Our understanding of how MSCs work in suppressing the immune system will lead to better utilization of these cells as a promising tool in the treatment of autoimmune diseases.

Mitochondrial fusion induced by transforming growth factor-β1 serves as a switch that governs the metabolic reprogramming during differentiation of regulatory T cells

Although metabolic reprogramming during the differentiation of regulatory T cells (Treg cells) has been extensively studied, the molecular switch to alter energy metabolism remains undefined. The present study explores the critical role of mitochondrial dynamics in the reprogramming and consequent generation of Treg cells. The results showed that during Treg cell differentiation, mitochondrial fusion but not fission led to elevation of oxygen consumption rate values, facilitation of metabolic reprogramming, and increase of number of Treg cells and expression of Foxp3 in vitro and in vivo. Mechanistically, mitochondrial fusion favored fatty acid oxidation but restricted glycolysis in Treg cells through down-regulating the expression of HIF-1α. Transforming growth factor-β1 (TGF-β1) played a crucial role in the induction of mitochondrial fusion, which activated Smad2/3, promoted the expression of PGC-1α and therefore facilitated the expression of mitochondrial fusion proteins. In conclusion, during Treg cell differentiation, TGF-β1 promotes PGC-1α-mediated mitochondrial fusion, which drives metabolic reprogramming from glycolysis to fatty acid oxidation via suppressing HIF-1α expression, and therefore favors the generation of Treg cells. The signals and proteins involved in mitochondrial fusion are potential therapeutic targets for Treg cell-related diseases.

Dominant immune cells in pregnancy and pregnancy complications: T helper cells (TH1/TH2, TH17/Treg cells), NK cells, MDSCs, and the immune checkpoints

Pregnancy problems including recurrent pregnancy loss, repeated implantation failure and pre-eclampsia  are common problems in the reproductive ages. Different reasons such as genetic, immunological, and environmental agents and also infections could develop these complications. In those cases in which the cause of the abortion is diagnosed, the chance of a successful pregnancy is increased by eliminating defective factors. However, in patients with unknown causes, there may be an imbalance in immune cells pattern. As a matter of fact, an inappropriate immune response is often associated with a failed pregnancy. Hence, the focus of treatment is to increase tolerance, not to suppress maternal immune system. These findings are linked to an elevated number of Treg cells and immune checkpoints through normal pregnancy. The present review discusses the balance of myeloid-derived suppressor cells, natural killer cells, T cells, and immune checkpoints, and also targeting them to maintain pregnancy and prevent associated complications.

Autoimmune pre-disease

Approximately 5% of the world-wide population is affected by autoimmune diseases. Overall, autoimmune diseases are still difficult to treat, impose a high burden on patients, and have a significant economic impact. Like other complex diseases, e.g., cancer, autoimmune diseases develop over several years. Decisive steps in the development of autoimmune diseases are (i) the development of autoantigen-specific lymphocytes and (often) autoantibodies and (ii) potentially clinical disease manifestation at a later stage. However, not all healthy individuals with autoantibodies develop disease manifestations. Identifying autoantibody-positive healthy individuals and monitoring and inhibiting their switch to inflammatory autoimmune disease conditions are currently in their infancy. The switch from harmless to inflammatory autoantigen-specific T and B-cell and autoantibody responses seems to be the hallmark for the decisive factor in inflammatory autoimmune disease conditions. Accordingly, biomarkers allowing us to predict this progression would have a significant impact. Several factors, such as genetics and the environment, especially diet, smoking, exposure to pollutants, infections, stress, and shift work, might influence the progression from harmless to inflammatory autoimmune conditions. To inspire research directed at defining and ultimately targeting autoimmune predisease, here, we review published evidence underlying the progression from health to autoimmune predisease and ultimately to clinically manifest inflammatory autoimmune disease, addressing the following 3 questions: (i) what is the current status, (ii) what is missing, (iii) and what are the future perspectives for defining and modulating autoimmune predisease.

Rheumatoid arthritis caused by non-tuberculous mycobacteria infection

A 72-year-old Japanese woman had right digital flexor tenosynovitis with a non-tuberculous mycobacteria (NTM) infection, which was identified as Mycobacterium marinum in culture. She had been treated at another hospital with clarithromycin, rifampicin, and ethambutol for the non-tuberculous tenosynovitis. However, the swelling of her right hand worsened, and 5 months later, her left hand swelled and she exhibited symmetrical arthritis. Blood tests detected elevated serum C-reactive protein and rheumatoid factor positivity. Although rheumatoid arthritis (RA) was suspected and corticosteroid treatment was started, she came to our hospital because of the insufficient treatment effect. Musculoskeletal ultrasonography showed intra-articular and peritendinous power Doppler signal-positive symmetrical synovitis. A contrast-enhanced magnetic resonance imaging (MRI) evaluation of the left hand without NTM tenosynovitis revealed findings of inflammatory synovitis accompanied by bone marrow oedema. We diagnosed RA and started treatment with weekly low-dose methotrexate pulses and 2 weeks of tocilizumab administration; her symptoms then disappeared within 2 months. This is a rare case of RA manifested with NTM-associated arthritis.

Impact of fibre and red/processed meat intake on treatment outcomes among patients with chronic inflammatory diseases initiating biological therapy: A prospective cohort study

Background

Biologic disease-modifying drugs have revolutionised the treatment of a number of chronic inflammatory diseases (CID). However, up to 60% of the patients do not have a sufficient response to treatment and there is a need for optimization of treatment strategies.

Objective

To investigate if the treatment outcome of biological therapy is associated with the habitual dietary intake of fibre and red/processed meat in patients with a CID.

Methods

In this multicentre prospective cohort study, we consecutively enrolled 233 adult patients with a diagnosis of Crohn's Disease, Ulcerative Colitis, Rheumatoid Arthritis (RA), Axial Spondyloarthritis, Psoriatic Arthritis and Psoriasis, for whom biologic therapy was planned, over a 3 year period. Patients with completed baseline food frequency questionnaires were stratified into a high fibre/low red and processed meat exposed group (HFLM) and an unexposed group (low fibre/high red and processed meat intake = LFHM). The primary outcome was the proportion of patients with a clinical response to biologic therapy after 14-16 weeks of treatment.

Results

Of the 193 patients included in our primary analysis, 114 (59%) had a clinical response to biologic therapy. In the HFLM group (N = 64), 41 (64%) patients responded to treatment compared to 73 (56%) in the LFHM group (N = 129), but the difference was not statistically significant (OR: 1.48, 0.72-3.05). For RA patients however, HFLM diet was associated with a more likely clinical response (82% vs. 35%; OR: 9.84, 1.35-71.56).

Conclusion

Habitual HFLM intake did not affect the clinical response to biological treatment across CIDs. HFLM diet in RA patients might be associated with better odds for responding to biological treatment, but this would need confirmation in a randomised trial.

Trial registration

(clinicaltrials.gov), identifier [NCT03173144].

Osteogenesis imperfecta and rheumatoid arthritis: connective issues

The coexistence of osteogenesis imperfecta and inflammatory arthritis has been very rarely described. Nevertheless, systemic inflammation has been found in osteogenesis imperfecta. The COL1A1 mutations may affect collagen synthesis as well as post-translational modifications, extracellular matrix interactions, and receptor-mediated signaling. Major collagen binding ligands forming the interactome, such as cytokines, cell adhesion molecules, matrix metalloproteinases, proteoglycans, and other molecules, are autoimmunity targets involved in rheumatoid arthritis pathogenesis. Cross-talk between bone remodeling and inflammatory pathways involving osteoclasts is important in osteogenesis imperfecta and rheumatoid arthritis. In osteogenesis imperfecta, the structural abnormalities and repeated traumatism, including fractures, could activate locally the innate immunity and trigger arthritis, similar to post-traumatic arthritis. Currently, the therapy of osteogenesis imperfecta is a suboptimally met need. Understanding the complex putative pathogenic links between osteogenesis imperfecta and inflammatory arthritis could hopefully lead to new therapeutic targets. Raising awareness regarding a possible association between osteogenesis imperfecta and arthritis could help improve the quality of life in these patients.

The RING finger protein family in health and disease

Ubiquitination is a highly conserved and fundamental posttranslational modification (PTM) in all eukaryotes regulating thousands of proteins. The RING (really interesting new gene) finger (RNF) protein, containing the RING domain, exerts E3 ubiquitin ligase that mediates the covalent attachment of ubiquitin (Ub) to target proteins. Multiple reviews have summarized the critical roles of the tripartite-motif (TRIM) protein family, a subgroup of RNF proteins, in various diseases, including cancer, inflammatory, infectious, and neuropsychiatric disorders. Except for TRIMs, since numerous studies over the past decades have delineated that other RNF proteins also exert widespread involvement in several diseases, their importance should not be underestimated. This review summarizes the potential contribution of dysregulated RNF proteins, except for TRIMs, to the pathogenesis of some diseases, including cancer, autoimmune diseases, and neurodegenerative disorder. Since viral infection is broadly involved in the induction and development of those diseases, this manuscript also highlights the regulatory roles of RNF proteins, excluding TRIMs, in the antiviral immune responses. In addition, we further discuss the potential intervention strategies targeting other RNF proteins for the prevention and therapeutics of those human diseases.

Harnessing the inherent power of chimeric antigen receptor (CAR)-expressing regulatory T cells (CAR-Tregs) to treat autoimmune-related disorders

Over the past years, adoptive cell therapy with regulatory T lymphocytes (Tregs) has captured the attention of many scientists and clinicians as a novel promising approach for treating a wide range of immune-mediated disorders. In particular, the robust immunosuppressive properties of these cells have been demonstrated to make them uniquely valuable for the treatment of autoimmune diseases. More recently, it has been brought to light that adoptive transfer of chimeric antigen receptor (CAR) Tregs (CAR-Tregs) can also serve a protective role against autoimmune-related disorders. Interestingly, a growing body of evidence indicates that the beneficial and therapeutic effects of antigen-specific CAR-Tregs surpass those of polyclonal Tregs in treating autoimmune conditions. Therefore, harnessing and adapting CAR technology to generate more specific and effective CAR-Tregs, both in terms of tissue localization and antigen recognition, may lay the foundations for the development of far more potent immunotherapeutic strategies for autoimmune-related disorders. Herein, we first highlight the major immunosuppressive abilities of CAR-Tregs and further summarize the current findings on their potential applications in treating autoimmune-related disorders. Then, we will attempt to address the practical challenges in the clinical use of CAR-Treg therapies.

Revealing the Immune Heterogeneity between Systemic Lupus Erythematosus and Rheumatoid Arthritis Based on Multi-Omics Data Analysis

The pathogenesis of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are greatly influenced by different immune cells. Nowadays both T-cell receptor (TCR) and B-cell receptor (BCR) sequencing technology have emerged with the maturity of NGS technology. However, both SLE and RA peripheral blood TCR or BCR repertoire sequencing remains lacking because repertoire sequencing is an expensive assay and consumes valuable tissue samples. This study used computational methods TRUST4 to construct TCR repertoire and BCR repertoire from bulk RNA-seq data of both SLE and RA patients’ peripheral blood and analyzed the clonality and diversity of the immune repertoire between the two diseases. Although the functions of immune cells have been studied, the mechanism is still complicated. Differentially expressed genes in each immune cell type and cell–cell interactions between immune cell clusters have not been covered. In this work, we clustered eight immune cell subsets from original scRNA-seq data and disentangled the characteristic alterations of cell subset proportion under both SLE and RA conditions. The cell–cell communication analysis tool CellChat was also utilized to analyze the influence of MIF family and GALECTIN family cytokines, which were reported to regulate SLE and RA, respectively. Our findings correspond to previous findings that MIF increases in the serum of SLE patients. This work proved that the presence of LGALS9, PTPRC and CD44 in platelets could serve as a clinical indicator of rheumatoid arthritis. Our findings comprehensively illustrate dynamic alterations in immune cells during pathogenesis of SLE and RA. This work identified specific V genes and J genes in TCR and BCR that could be used to expand our understanding of SLE and RA. These findings provide a new insight inti the diagnosis and treatment of the two autoimmune diseases.

Yields of mesenchymal stromal cells from synovial fluid reflect those from synovium in patients with rheumatoid arthritis

The yield of primary synovial mesenchymal stromal cells (MSCs) from synovium of patients with rheumatoid arthritis (RA) is highly variable, but cell transplantation therapy with autologous synovial MSCs requires accurate prediction of the synovial MSC yield per synovium weight. Here, we determined whether the yield of synovial fluid MSCs might predict the ultimate yield of primary MSCs from the synovium of RA knees. Synovial fluid and synovium were harvested during total knee arthroplasty from the knee joints of 10 patients with RA. Synovial fluid (1.5 mL) was diluted fourfold and plated equally into six 60 cm² dishes. Nucleated cells from digested synovium were similarly plated at 1 × 10⁴ cells in 6 dishes. All dishes were cultured for 14 days and analyzed for MSC yields and properties, including in vitro chondrogenesis. The cultured synovial cell number was correlated with the cultured synovial fluid cell number (n = 10, R² = 0.64, p < 0.01). Synovial fluid cells formed cell colonies and showed MSC-like surface epitopes and multi-differentiation potential. However, the cartilage pellet weight indicated a greater chondrogenic potential of the synovial MSCs (n = 8). The primary MSC yields from synovial fluid and synovium were correlated, indicating that the synovial fluid MSC yield can predict the ultimate synovial MSC yield.

Autoinflammation: Interferonopathies and Other Autoinflammatory Diseases

The family of autoinflammatory diseases (AIDs) continues to expand and now includes over 40 genetically defined disorders. Their defining feature is a dysregulated inflammatory innate immune response. Many AIDs have overlapping clinical characteristics, and dermatological manifestations are common. Autoinflammatory features have also been recognized in more common dermatological conditions such as psoriasis. Furthermore, there is an increasing understanding that immunodeficiencies, autoimmune disorders, and even some allergic disorders share overlapping autoinflammatory features. The discovery that certain somatic mutations, arising within the bone marrow and restricted to the myeloid cell lineage can cause acquired AID heralds a new era of discoveries in this field.

The Genetic, Environmental, and Immunopathological Complexity of Autoantibody-Negative Rheumatoid Arthritis

Differences in clinical presentation, response to treatment, and long-term outcomes between autoantibody-positive and -negative rheumatoid arthritis (RA) highlight the need for a better comprehension of the immunopathogenic events underlying the two disease subtypes. Whilst the drivers and perpetuators of autoimmunity in autoantibody-positive RA have started to be disclosed, autoantibody-negative RA remains puzzling, also due its wide phenotypic heterogeneity and its possible misdiagnosis. Genetic susceptibility appears to mostly rely on class I HLA genes and a number of yet unidentified non-HLA loci. On the background of such variable genetic predisposition, multiple exogeneous, endogenous, and stochastic factors, some of which are not shared with autoantibody-positive RA, contribute to the onset of the inflammatory cascade. In a proportion of the patients, the immunopathology of synovitis, at least in the initial stages, appears largely myeloid driven, with abundant production of proinflammatory cytokines and only minor involvement of cells of the adaptive immune system. Better understanding of the complexity of autoantibody-negative RA is still needed in order to open new avenues for targeted intervention and improve clinical outcomes.

Autoinflammation and autoimmunity across rheumatic and musculoskeletal diseases

Most rheumatic and musculoskeletal diseases (RMDs) can be placed along a spectrum of disorders, with autoinflammatory diseases (including monogenic systemic autoinflammatory diseases) and autoimmune diseases (such as systemic lupus erythematosus and antiphospholipid syndrome) representing the two ends of this spectrum. However, although most autoinflammatory diseases are characterized by the activation of innate immunity and inflammasomes and classical autoimmunity typically involves adaptive immune responses, there is some overlap in the features of autoimmunity and autoinflammation in RMDs. Indeed, some 'mixed-pattern' diseases such as spondyloarthritis and some forms of rheumatoid arthritis can also be delineated. A better understanding of the pathogenic pathways of autoinflammation and autoimmunity in RMDs, as well as the preferential cytokine patterns observed in these diseases, could help us to design targeted treatment strategies.

COVID-19 and RA share an SPP1 myeloid pathway that drives PD-L1+ neutrophils and CD14+ monocytes

We explored the potential link between chronic inflammatory arthritis and COVID-19 pathogenic and resolving macrophage pathways and their role in COVID-19 pathogenesis. We found that bronchoalveolar lavage fluid (BALF) macrophage clusters FCN1+ and FCN1+SPP1+ predominant in severe COVID-19 were transcriptionally related to synovial tissue macrophage (STM) clusters CD48hiS100A12+ and CD48+SPP1+ that drive rheumatoid arthritis (RA) synovitis. BALF macrophage cluster FABP4+ predominant in healthy lung was transcriptionally related to STM cluster TREM2+ that governs resolution of synovitis in RA remission. Plasma concentrations of SPP1 and S100A12 (key products of macrophage clusters shared with active RA) were high in severe COVID-19 and predicted the need for Intensive Care Unit transfer, and they remained high in the post-COVID-19 stage. High plasma levels of SPP1 were unique to severe COVID-19 when compared with other causes of severe pneumonia, and IHC localized SPP1+ macrophages in the alveoli of COVID-19 lung. Investigation into SPP1 mechanisms of action revealed that it drives proinflammatory activation of CD14+ monocytes and development of PD-L1+ neutrophils, both hallmarks of severe COVID-19. In summary, COVID-19 pneumonitis appears driven by similar pathogenic myeloid cell pathways as those in RA, and their mediators such as SPP1 might be an upstream activator of the aberrant innate response in severe COVID-19 and predictive of disease trajectory including post-COVID-19 pathology.

Palindromic rheumatism: Evidence of four subtypes of palindromic-like arthritis based in either MEFV or rheumatoid factor/ACPA status

INTRODUCTION

MEFV mutations have been documented in patients with palindromic rheumatism (PR) who do not meet FMF criteria, and RF and ACPA positive RA may start with PR.

OBJECTIVE

To analyze the clinical phenotype and disease evolution of patients with intermittent, palindromic-like (PL) arthritis seen in our Arthritis Unit according to the RF, ACPA and MEFV mutation status.

METHODS

MEFV genotyping was done in 76 patients with PL arthritis as defined by predominantly short attacks (≤7days) and a relapsing course. Characteristics of arthritic episodes, RF and ACPA positivity, and the colchicine response were retrospectively collected. Patients were stratified and evaluated according to MEFV mutations and/or positive autoantibodies (ACPA and/or RF).

RESULTS

Among the patients, 26.3% (20/76) had a MEFV mutation and 23 (30%) were ACPA and/or RF positive. MEFV mutations and/or autoantibody status allowed four PL arthritis patients to be distinguished: group I (MEFV+), with younger age of onset, short duration attacks (<3days), mainly located in the knee, more frequent non-articular manifestations (fever, pericarditis or abdominal pain) and good response to colchicine; group II (autoantibody+) is older than group I, with the same frequency of short attacks, but the most affected joints were the wrists and small joints of hands: 48% met RA classification criteria during follow-up and were taking DMARDs; group III (MEFV- and autoantibody-) was the most frequent (48%) and clinically heterogeneous group; 51% had attacks lasting>3days, and 15 patients developed criteria of immune-mediated inflammatory, autoinflammatory or infectious diseases. Group IV (MEFV+ associated with preexisting immune-inflammatory disease), was associated with very short attacks, like groups I and II, superimposed or coincident with definite immune-inflammatory disease, including seropositive RA, with good response to colchicine.

CONCLUSIONS

Patients with PL arthritis can be classified in four groups according to the presence or not of MEFV mutations and ACPA/RF antibodies with a different clinical evolution and therapeutic response.

Multipotent Mesenchymal Stromal Cells in Rheumatoid Arthritis and Systemic Lupus Erythematosus; From a Leading Role in Pathogenesis to Potential Therapeutic Saviors?

The pathogenesis of the autoimmune rheumatological diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) is complex with the involvement of several immune cell populations spanning both innate and adaptive immunity including different T-lymphocyte subsets and monocyte/macrophage lineage cells. Despite therapeutic advances in RA and SLE, some patients have persistent and stubbornly refractory disease. Herein, we discuss stromal cells' dual role, including multipotent mesenchymal stromal cells (MSCs) also used to be known as mesenchymal stem cells as potential protagonists in RA and SLE pathology and as potential therapeutic vehicles. Joint MSCs from different niches may exhibit prominent pro-inflammatory effects in experimental RA models directly contributing to cartilage damage. These stromal cells may also be key regulators of the immune system in SLE. Despite these pro-inflammatory roles, MSCs may be immunomodulatory and have potential therapeutic value to modulate immune responses favorably in these autoimmune conditions. In this review, the complex role and interactions between MSCs and the haematopoietically derived immune cells in RA and SLE are discussed. The harnessing of MSC immunomodulatory effects by contact-dependent and independent mechanisms, including MSC secretome and extracellular vesicles, is discussed in relation to RA and SLE considering the stromal immune microenvironment in the diseased joints. Data from translational studies employing MSC infusion therapy against inflammation in other settings are contextualized relative to the rheumatological setting. Although safety and proof of concept studies exist in RA and SLE supporting experimental and laboratory data, robust phase 3 clinical trial data in therapy-resistant RA and SLE is still lacking.

Identification of New, Functionally Relevant Mutations in the Coding Regions of the Human Fos and Jun Proto-Oncogenes in Rheumatoid Arthritis Synovial Tissue

In rheumatoid arthritis (RA), the expression of many pro-destructive/pro-inflammatory proteins depends on the transcription factor AP-1. Therefore, our aim was to analyze the presence and functional relevance of mutations in the coding regions of the AP-1 subunits of the fos and jun family in peripheral blood (PB) and synovial membranes (SM) of RA and osteoarthritis patients (OA, disease control), as well as normal controls (NC). Using the non-isotopic RNAse cleavage assay, one known polymorphism (T252C: silent; rs1046117; present in RA, OA, and NC) and three novel germline mutations of the cfos gene were detected: (i) C361G/A367G: Gln121Glu/Ile123Val, denoted as “fos121/123”; present only in one OA sample; (ii) G374A: Arg125Lys, “fos125”; and (iii) C217A/G374A: Leu73Met/Arg125Lys, “fos73/125”, the latter two exclusively present in RA. In addition, three novel somatic cjun mutations (604–606ΔCAG: ΔGln202, “jun202”; C706T: Pro236Ser, “jun236”; G750A: silent) were found exclusively in the RA SM. Tansgenic expression of fos125 and fos73/125 mutants in NIH-3T3 cells induced an activation of reporter constructs containing either the MMP-1 (matrix metalloproteinase) promoter (3- and 4-fold, respectively) or a pentameric AP-1 site (approximately 5-fold). Combined expression of these two cfos mutants with cjun wildtype or mutants (jun202, jun236) further enhanced reporter expression of the pentameric AP-1 construct. Finally, genotyping for the novel functionally relevant germline mutations in 298 RA, 288 OA, and 484 NC samples revealed no association with RA. Thus, functional cfos/cjun mutants may contribute to local joint inflammation/destruction in selected patients with RA by altering the transactivation capacity of AP-1 complexes.

Persistent inflammatory and non-inflammatory mechanisms in refractory rheumatoid arthritis

Despite nearly three decades of advances in the management of rheumatoid arthritis (RA), a substantial minority of patients are exposed to multiple DMARDs without necessarily benefitting from them; a group of patients variously designated as having 'difficult to treat', 'treatment-resistant' or 'refractory' RA. This Review of refractory RA focuses on two types of patients: those for whom multiple targeted therapies lack efficacy and who have persistent inflammatory pathology, which we designate as persistent inflammatory refractory RA (PIRRA); and those with supposed refractory RA who have continued disease activity that is predominantly independent of objective evidence of inflammation, which we designate as non-inflammatory refractory RA (NIRRA). These two types of disease are not mutually exclusive, but identifying those individuals with predominant PIRRA or NIRRA is important, as it informs distinct treatment and management approaches. This Review outlines the clinical differences between PIRRA and NIRRA, the genetic and epigenetic mechanisms and immune pathways that might contribute to the immunopathogenesis of recalcitrant synovitis in PIRRA, and a possible basis for non-inflammatory symptomatology in NIRRA. Future approaches towards the definition of refractory RA and the application of single-cell and integrated omics technologies to the identification of refractory RA endotypes are also discussed.

The metabolic signature of T cells in rheumatoid arthritis

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) is a prototypic autoimmune disease manifesting as chronic inflammation of the synovium and leading to acceleration of cardiovascular disease and shortening of life expectancy. The basic defect causing autoimmunity has remained elusive, but recent insights have challenged the notion that autoantigen is the core driver.

RECENT FINDINGS

Emerging data have added metabolic cues involved in the proper maintenance and activation of immune cells as pathogenic regulators. Specifically, studies have unveiled metabolic pathways that enforce T cell fate decisions promoting tissue inflammation; including T cell tissue invasiveness, T cell cytokine release, T cell-dependent macrophage activation and inflammatory T cell death. At the center of the metabolic abnormalities lies the mitochondria, which is consistently underperforming in RA T cells. The mitochondrial defect results at least partially from insufficient DNA repair and leads to lipid droplet accumulation, formation of invasive membrane ruffles, inflammasome activation and pyroptotic T cell death.

SUMMARY

T cells in patients with RA, even naïve T cells never having been involved in inflammatory lesions, have a unique metabolic signature and the changes in intracellular metabolites drive pathogenic T cell behavior. Recognizing the role of metabolic signals in cell fate decisions opens the possibility for immunomodulation long before the end stage synovial inflammation encountered in clinical practice.

Proteomic analysis of synovial fluid from rheumatic arthritis and spondyloarthritis patients

Background

The aetiologies and pathogeneses of the joint diseases rheumatoid arthritis (RA) and spondyloarthritis (SpA) are still not fully elucidated. To increase our understanding of the molecular pathogenesis, we analysed the protein composition of synovial fluid (SF) from rheumatoid arthritis (RA) and spondyloarthritis (SpA) patients.

Methods

Fifty-six synovial fluid samples (RA, n = 32; SpA, n = 24) were digested with trypsin, and the resulting peptides were separated by liquid chromatography and analysed by tandem mass spectrometry. Additionally, the concentration of cell-free DNA (cfDNA) in the synovial fluid was measured, and plasma C-reactive protein (CRP) was determined.

Results

Three hundred thirty five proteins were identified within the SF. The more abundant proteins seen in RA SF were inflammatory proteins, including proteins originating from neutrophil granulocytes, while SpA SF had less inflammatory proteins and a higher concentration of haptoglobin. The concentration of cell-free DNA in the SF increased together with proteins that may have originated from neutrophils. Plasma CRP levels in both RA and SpA, correlated to other acute phase reactants.

Conclusions

The proteomic results underline that neutrophils are central in the RA pathology but not in SpA, and even though inhibitors of neutrophils (migration, proteinase inhibitors) were present in the SF it was not sufficient to interrupt the disease process.

The IL-1 family cytokines and receptors in autoimmune diseases

The role of the cytokines and receptors of the IL-1 family in inflammation is well known. Several cytokines of the family have a powerful inflammatory activity, with IL-1β being the best-characterized factor. The inflammatory activity of IL-1 cytokines is regulated by other factors of the family, including receptor antagonists, soluble receptors and anti-inflammatory cytokines. The causative role of IL-1β is well-established in autoinflammatory diseases, mainly due to gain-of-function mutations in genes encoding the IL-1β-maturing inflammasome. Exaggerated production of IL-1β and IL-18 correlates with disease and disease severity also in several autoimmune and chronic inflammatory and degenerative pathologies, although it is not clear whether they have a causative role or are only involved in the downstream disease symptoms. A better understanding of the pathological role of IL-1 family cytokines in autoimmunity involves a deeper evaluation, in the pathological situations, of the possible anomalies in the feed-back anti-inflammatory mechanisms that in physiological reactions control and dump IL-1-mediated inflammation. Thus, we expect that IL-1 cytokines may be pathogenic only when, in addition to enhanced production, there is a concomitant failure of their control mechanisms. In this review we will examine the current knowledge on the role of IL-1 family cytokines in autoimmune and chronic inflammatory and degenerative diseases, with a particular focus on their endogenous control mechanisms, mainly based on soluble receptors/inhibitors and receptor antagonists. This will allow us to formulate a knowledge-based hypothesis on the involvement of IL-1 cytokines in the pathogenesis vs. the clinical features of these diseases.

Anti-arthritic and anti- inflammatory effects of extract and fractions of Malva parviflora in a mono- arthritis model induced with kaolin/carrageenan

Malva parviflora is used as food in the gastronomy of some regions of Mexico and, also, in Mexican traditional medicine for inflammation-related conditions like rheumatoid arthritis. The objective of this work was to evaluate its antiarthritic activity in a mice model. In ICR, female mice were tested the dichloromethane extract (MpD) and fractions MpF4 (extracted with a dichoromethane:methanol system) and MpFphy (a precipitate by acetone:methanol) by using the mono-arthritis with kaolin/carrageenan model. During the treatment, joint inflammation was measured daily, and hyperalgesia was measured using the hot plate test. The treatments diminished both joint inflammation and pain. At the end of the evaluation, the left joint and spleen were extracted for determination of pro- and anti-inflammatory cytokines. The results showed that the MpD, MpF4, and MpFphy treatments modulated the concentration of these proteins. Specifically, MpFphy at 1.0 mg/kg increased IL-4 and IL-10 and decreased IL-17, IL-1β, and TNF-α. GC-MS analysis showed that MpF4 contained a mixture of a total of nine compounds, three of them newly reported for the species. The studies confirmed the presence of five sterols in the MpFphy fraction, including stigmasterol and β-sitosterol. These results confirm the anti-rheumatoid and anti-inflammatory activities of a fraction rich in sterols from Malva parviflora. Graphical abstract.

From hepatitis C virus immunoproteomics to rheumatology via cross-reactivity in one table

PURPOSE OF REVIEW

To give an overview of molecular and immunologic data that link hepatitis C virus (HCV) infection to rheumatic diseases in the human host.

RECENT FINDINGS

A high level of peptide sharing exists between immunopositive HCV epitopes and human proteins that, when altered, associate with rheumatic manifestations.

SUMMARY

The findings suggest the involvement of HCV infection in the induction of most rheumatic diseases via a mechanism of autoimmune cross-reactivity.

Ginsenoside Rg3 Alleviates Complete Freund's Adjuvant-Induced Rheumatoid Arthritis in Mice by Regulating CD4+CD25+Foxp3+Treg Cells

Ginsenoside Rg3 (GRg3) is one of the major bioactive ingredients of ginseng, which is not only used as a herbal medicine but also used as a functional food to support body functions. In this study, the beneficial effects of GRg3 on rheumatoid arthritis (RA) mice was evaluated from anti-inflammatory and immunosuppressive aspects. The footpad swelling rate, pathological changes of the ankle joint, and levels of tumor necrosis factor α, interleukin 6, interleukin 10, and tumor necrosis factor β were used to assess the anti-inflammatory effect of GRg3 on RA mice. Flow cytometric analysis of CD4⁺CD25⁺Foxp3⁺Treg cell percentage and metabolomic analysis based on gas chromatography-tandem mass spectrometry were used to assess the immunosuppressive effect and underlying mechanisms. GRg3 exhibited anti-inflammatory and immunosuppressive effects on RA mice. The potential mechanisms were related to regulate the pathways of oxidative phosphorylation and enhance the function of CD4⁺CD25⁺Foxp3⁺Treg cells to maintain peripheral immune tolerance of RA mice. These findings can provide a preliminary experimental basis to exploit GRg3 as a functional food or an effective complementary for the adjuvant therapy of RA.

Moving towards a systems-based classification of innate immune-mediated diseases

Autoinflammation as a distinct disease category was first reported in 1999 as a group of monogenic disorders characterized by recurrent episodes of systemic and organ-specific inflammation, known as periodic fever syndromes. Since this original description, the focus has shifted considerably to the inclusion of complex multifactorial conditions with an autoinflammatory basis. Furthermore, the boundaries of what are considered to be autoinflammatory disorders are constantly evolving and currently encompass elements of immunodeficiency and autoimmunity. Notable developments in the intervening 20 years include substantial progress in understanding how the different inflammasomes are activated, how infection is sensed by the innate immune system and how intracellular signalling systems are consequently activated and integrated with many different cellular functions in the autoinflammatory process. With these developments, the field of autoinflammation is moving from a gene-centric view of innate immune-mediated disease towards a systems-based concept, which describes how various convergent pathways, including pyrin and the actin cytoskeleton, protein misfolding and cellular stress, NF-κB dysregulation and interferon activation, contribute to the autoinflammatory process. The development and adoption of a systems-based concept of systemic autoinflammatory diseases is anticipated to have implications for the development of treatments that target specific components of the innate immune system.

Involvement of long noncoding RNAs in the pathogenesis of autoimmune diseases

Autoimmune diseases are a group of heterogeneous disorders characterized by damage to various organs caused by abnormal innate and adaptive immune responses. The pathogenesis of autoimmune diseases is extremely complicated and has not yet been fully elucidated. Long noncoding RNAs (lncRNAs), which are defined as transcripts containing more than 200 nucleotides with no protein-coding capacity, are emerging as important regulators of gene expression via epigenetic modification, transcriptional regulation and posttranscriptional regulation. Accumulating evidence has demonstrated that lncRNAs play a key role in the regulation of immunological functions and autoimmunity. In this review, we discuss various molecular mechanisms by which lncRNAs regulate gene expression and recent findings regarding the involvement of lncRNAs in many human autoimmune diseases, including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), idiopathic inflammatory myopathy (IIM), systemic sclerosis (SSc) and Sjögren’s syndrome (pSS).

•

lncRNAs are observed to be differentially expressed in various autoimmune diseases.

•

lncRNAs are involved in abnormal immune regulation and inflammatory responses in autoimmune diseases, which provides new insight into disease pathogenesis.

•

LncRNAs may have the potential of biomarkers for diagnosis and prognosis of autoimmune diseases.

Osteogenesis imperfecta and rheumatoid arthritis: is there a link?

We present the cases of a mother and daughter with osteogenesis imperfecta, also diagnosed later with rheumatoid arthritis. In our patients finding and treating the over-imposed arthritis improved the joint pain initially attributed to osteogenesis imperfecta. Exploring joint inflammation in this setting could help ease the disease burden.

PURPOSE

Osteogenesis imperfecta (OI) is a rare hereditary disease evolving with recurrent fractures upon minor trauma, blue sclerae, and hearing loss. Although inflammation was not generally considered a feature of the disease, systemic inflammation was recently reported in children with OI and in murine models of OI.

METHOD

We present the cases of a mother and a daughter with OI, without a personal or family history of autoimmune diseases, who were also diagnosed with rheumatoid arthritis seropositive for anti-cyclic citrullinated peptide autoantibodies and rheumatoid factor.

RESULTS

The genetic tests identified in both patients a deletion in COL1A1 gene (c.3399del, p.Ala1134Profs*105), not previously reported, not present in population databases, creating a premature translational stop signal in the COL1A1 gene in the collagen I major ligand binding region 3. In our patients finding and treating the over-imposed arthritis improved the joint pain initially attributed to OI. Possible pathogenic links between OI and RA are discussed.

CONCLUSION

The prevalence of joint inflammation in OI is unknown and may be underestimated. As musculoskeletal involvement affects the quality of life in most OI patients, exploring this relation may help ease the disease burden.

Targeting bioenergetics prevents CD4 T cell–mediated activation of synovial fibroblasts in rheumatoid arthritis

Objectives

We investigated the reciprocal relationship linking fibroblast-like synoviocytes (FLS) and T lymphocytes in the inflamed RA synovium and subsequently targeted cellular metabolic pathways in FLS to identify key molecular players in joint inflammation.

Methods

RA FLS were cultured with CD4 T cells or T cell conditioned medium (CD4CM); proliferation, expression of adhesion molecules and intracellular cytokines were examined by flow cytometry. FLS invasiveness and secreted cytokines were measured by transwell matrigel invasion chambers and ELISA, while metabolic profiles were determined by extracellular Seahorse flux analysis. Gene expression was quantified by real-time quantitative RT-PCR.

Results

Our results showed mutual activation between CD4 T cells and FLS, which resulted in increased proliferation and expression of intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 by both CD4 T cells and FLS. Furthermore, interaction between CD4 T cells and FLS resulted in an increased frequency of TNF-α+, IFN-γ+ and IL-17A+ CD4 T cells and augmented TNF-α, IFN-γ, IL-17A, IL-6, IL-8 and VEGF secretion. Moreover, CD4CM promoted invasiveness and boosted glycolysis in FLS while downregulating oxidative phosphorylation, effects paralleled by increased glucose transporters GLUT1 and GLUT3; key glycolytic enzymes GSK3A, HK2, LDHA and PFKFB3; angiogenic factor VEGF and MMP-3 and MMP-9. Importantly, these effects were reversed by the glycolytic inhibitor 2-DG and AMP analogue 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR).

Conclusion

This study demonstrates that CD4 T cells elicit an aggressive phenotype in FLS, which subsequently upregulate glycolysis to meet the increased metabolic demand. Accordingly, 2-DG and AICAR prevent this activation, suggesting that glycolytic manipulation could have clinical implications for RA treatment.

Association among anti-citrullinated protein antibody status, erosive disease and healthcare resource utilization in patients with rheumatoid arthritis

Objective: To characterize the rate of healthcare resource utilization (HCRU) between anti-cyclic citrullinated peptide (CCP; a surrogate for anti-citrullinated protein antibodies [ACPAs]) positive (+) patients with rheumatoid arthritis (RA), either with or without erosions, who initiated biologic disease-modifying antirheumatic drug (bDMARD) treatment.Methods: Data from the Corrona RA registry, a prospective registry of adult patients with RA from 177 sites across 42 states in the US, were analyzed. Annual rates of HCRU (measured based on rates of all-cause hospitalization, joint surgery, imaging procedures and use of assistive devices) were estimated in anti-CCP + patients with and without erosions following bDMARD initiation using a Poisson regression model.Results: Among the 3333 patients with known anti-CCP and erosion status and 12-month post-bDMARD follow-up information in the Corrona registry, 2047 were anti-CCP + and included in this analysis; 868 with and 1179 without erosions. Baseline characteristics were generally well balanced between patients with and without erosions; however, those with erosions had a longer mean RA duration and a higher prior DMARD use. Over 12 months, among anti-CCP + patients, those with erosions had significantly higher rates of all HCRU, except joint surgery, than those without erosions. Age-adjusted risk ratios (95% confidence interval) were as follows: all-cause hospitalization, 1.47 (1.14, 1.90); all-cause imaging, 1.25 (1.03, 1.53); and assistive device use 1.12 (1.00, 1.25). The rate of joint surgery visits was also numerically higher in patients with versus without erosion.Conclusions: ACPA seropositivity with erosive disease was associated with higher rates of HCRU compared with seropositivity without erosions. These findings suggest that providers may want to manage anti-CCP + patients aggressively to achieve better disease control to prevent the development of erosions and the associated increase in HCRU.

FMF Is Associated With a Wide Spectrum of MHC Class I- and Allied SpA Disorders but Not With Classical MHC Class II-Associated Autoimmune Disease: Insights From a Large Cohort Study

Objectives: To test the hypothesis that familial Mediterranean fever (FMF)-associated autoinflammation may exaggerate the tendency toward adaptive immunopathology or spondyloarthritis (SpA)-associated disorders including major histocompatibility complex (MHC) class I associated disorders but not classical MHC class II-associated disorders that exhibit transplacental autoimmunity including myasthenia gravis and pemphigus.

Methods: Seven thousand seven hundred forty-seven FMF patients and 10,080 age- and sex-matched controls in the Clalit Health Services medical database were identified and compared in terms of prevalence of SpA-associated disorders. We also evaluated four classical and strong MHC class II-associated disorders, namely, pemphigus vulgaris, myasthenia gravis, sarcoidosis, and pernicious anemia, to ascertain whether such associations with SpA-spectrum disease were specific or merely reflected the non-specific consequences of innate immune system activation on driving divergent types of immunity. The diagnosis of FMF was based on the medical records and not genetically proven.

Results: FMF showed a strong association with MHC class I-related diseases: odds ratio (OR) of 28.58 [95% confidence interval (95% CI), 6.93–117.87; p < 0.0001] for Behçet's disease, OR of 10.33 (95% CI, 4.09–26.09; p < 0.0001) for ankylosing spondylitis, and OR of 1.67 (95% CI, 1.19–2.33; p = 0.0029) for psoriasis. For weakly MHC class I-linked diseases, an OR of 3.76 (95% CI, 2.48–5.69; p < 0.0001) for Crohn's disease and OR of 2.64 (95% CI, 1.52–4.56; p = 0.0005) for ulcerative colitis were found. No association was found between FMF and the four MHC class II-associated autoimmune disorders.

Conclusion: FMF patients are associated with increased risk of SpA-related disease diagnosis including MHC-I-opathies but not MHC-II-associated autoimmune diseases, suggesting that tissue-specific dysregulation of innate immunity share between FMF and SpA spectrum disorders may drive adaptive immune MHC class I-associated conditions.

Dissecting the Role of NF-κb Protein Family and Its Regulators in Rheumatoid Arthritis Using Weighted Gene Co-Expression Network

Rheumatoid arthritis (RA) is a chronic synovial autoinflammatory disease that destructs the cartilage and bone, leading to disability. The functional regulation of major immunity-related pathways like nuclear factor kappa B (NF-κB), which is involved in the chronic inflammatory reactions underlying the development of RA, remains to be explored. Therefore, this study has adopted statistical and knowledge-based systemic investigations (like gene correlation, semantic similarity, and topological parameters based on graph theory) to study the gene expression status of NF-κB protein family (NK^PF) and its regulators in synovial tissues to trace the molecular pathways through which these regulators contribute to RA. A complex protein–protein interaction map (PPIM) of 2,742 genes and 37,032 interactions was constructed from differentially expressed genes (p ≤ 0.05). PPIM was further decomposed into a Regulator Allied Protein Interaction Network (RA^PIN) based on the interaction between genes (5 NK^PF, 31 seeds, 131 hubs, and 652 bottlenecks). Pathway network analysis has shown the RA-specific disturbances in the functional connectivity between seed genes (RIPK1, ATG7, TLR4, TNFRSF1A, KPNA1, CFLAR, SNW1, FOSB, PARVA, CX3CL1, and TRPC6) and NK^PF members (RELA, RELB, NFKB2, and REL). Interestingly, these genes are known for their involvement in inflammation and immune system (signaling by interleukins, cytokine signaling in immune system, NOD-like receptor signaling, MAPK signaling, Toll-like receptor signaling, and TNF signaling) pathways connected to RA. This study, for the first time, reports that SNW1, along with other NK regulatory genes, plays an important role in RA pathogenesis and might act as potential biomarker for RA. Additionally, these genes might play important roles in RA pathogenesis, as well as facilitate the development of effective targeted therapies. Our integrative data analysis and network-based methods could accelerate the identification of novel drug targets for RA from high-throughput genomic data.

Responses to Cytokine Inhibitors Associated with Cellular Composition in Models of Immune-Mediated Inflammatory Arthritis

Objective

Immune‐mediated inflammatory arthritis (IMIA) is a heterogeneous group of diseases including rheumatoid arthritis (RA), psoriatic arthritis (PsA), and spondyloarthritis (SpA). Disease‐modifying antirheumatic drugs (DMARDs) target very different cellular components of the disease processes. Characterization of the pathobiological subtypes of IMIA could provide more specific treatment approaches for each disease. For example, RA has been proposed to consist of at least three synovial pathotypes (lymphoid, myeloid, and fibroid), and only a subgroup of RA patients have erosive disease. The objective of this study was to evaluate the effects of various DMARDs on different synovial cell subsets using human ex vivo models of IMIA.

Methods

Synovial fluid and blood samples were obtained from a study population consisting of patients with RA, PsA, or peripheral SpA with at least one swollen joint (n = 18). The DMARDs used in this study were methotrexate, adalimumab, etanercept, tocilizumab, anakinra, ustekinumab, secukinumab, tofacitinib, and baricitinib. Paired synovial fluid mononuclear cells (SFMCs), peripheral blood mononuclear cells (PBMCs), and fibroblast‐like synovial cells (FLSs) were used in three different previously optimized ex vivo models.

Results

In SFMCs cultured for 48 hours, all DMARDs except anakinra decreased the production of monocyte chemoattractant protein (MCP)‐1. In SFMCs cultured for 21 days, only the two tumor necrosis factor alpha (TNFα) inhibitors adalimumab and etanercept decreased the secretion of tartrate‐resistant acid phosphatase (P < 0.01, P < 0.001). In the FLS and PBMC 48‐hour co‐cultures, only tocilizumab (P < 0.001) and the two Janus kinase inhibitors tofacitinib and baricitinib (both P < 0.05) decreased the production of MCP‐1 by around 50%.

Conclusion

TNFα inhibition was effective in preventing inflammatory osteoclastogenesis, whereas tocilizumab, tofacitinib, and baricitinib had superior efficacy in cultures dominated by FLSs. Taken together, this study reveals that responses to cytokine inhibitors associate with cellular composition in models of IMIA. In particular, this study provides new evidence on the differential effect of DMARDs on leukocytes compared with stromal cells.

The protective effects of the GPR39 agonist TC-G 1008 against TNF-α-induced inflammation in human fibroblast-like synoviocytes (FLSs)

Rheumatoid arthritis (RA) is a common immune-mediated chronic inflammatory joint disease of unknown etiology. While tumor necrosis factor-α(TNF-α) blockers have proven to be a beneficial treatment option for many patients, not all respond to such treatments. In the present study, we investigate the role of the recently discovered zinc-sensing G protein-couple receptor GPR39. To our knowledge, this study is the first to investigate the role of GPR39 in the context of RA using human fibroblast-like synoviocytes (FLS). We found that agonism of GPR39 using its specific agonist TC-G 1008 significantly ameliorated important markers of RA, including oxidative stress, mitochondrial dysfunction, expression of proinflammatory cytokines including interleukin-1β (IL-1β), IL-6, and monocyte chemoattractant protein 1 (MCP-1), and secretion of key matrix metalloproteinases (MMPs) including MMP-1, MMP-3 and MMP-13. Furthermore, we demonstrate that these may be mediated via the Janus-kinase (JNK), activating protein 1 (AP-1), and nuclear factor-κB (NF-κB) cellular signaling pathways. Our findings demonstrate for the first time the potential of GPR39 to mediate synovial inflammation, pannus invasion, and enzymatic degradation of articular extracellular matrix.

Antagonism of NK-1R using aprepitant suppresses inflammatory response in rheumatoid arthritis fibroblast-like synoviocytes

Chronic inflammation in fibroblast-like synoviocytes (FLSs) induced by pro-inflammatory cytokines such as TNF-α plays a key role in the pathogenesis of rheumatoid arthritis (RA). The neurokinin-1 receptor (NK-1R) is one of the G protein-coupled receptors (GPCRs) mediating the intracellular signalling of substance P (SP). However, the possible implications of NK-1R in rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) and the pathogenesis of RA have not yet been reported. In the current study, we report that NK-1R is expressed in FLSs. Importantly, NK-1R expression was found to be significantly increased in RA-FLSs compared to normal FLSs. Interestingly, we found that treatment with tumour necrosis factor (TNF)-α increased the expression of NK-1R at both the gene and protein levels. Treatment with the NK-1R antagonist aprepitant reduced TNF-α-induced expression of NADPH oxidase 4 (NOX-4) and generation of reactive oxygen species (ROS) in FLSs. Our results also display that blockage of NF-1R using aprepitant inhibited TNF-α-induced expression and secretion of proinflammatory cytokines, including interleukin-1β (IL-1β), IL-6, and IL-8. Consistently, aprepitant prevented TNF-α-induced expression of matrix metalloproteinases (MMPs), including matrix metalloproteinase-3 (MMP-3) and matrix metalloproteinase-13 (MMP-13). Mechanistically, our data demonstrate that treatment with aprepitant inhibited TNF-α-induced phosphorylation and degradation of inhibitor of NF-κB (IκBα). Notably, aprepitant attenuated TNF-α-induced nuclear translocation of nuclear factor κB (NF-κB) p65 and reduced luciferase activity of NF-κB in FLSs. The findings implicated a novel function of NK-1R in RA-FLSs. Blockage of NK-1R using its specific antagonist aprepitant might provide a new therapeutic strategy for RA.

[Rheumatoid arthritis: achievements and unresolved issues]

Success in a treatment of rheumatoid arthritis (RA), associated with a development of new medications and improving treatment strategies, allows to achieve remission in many patients. Despite this a lot of theoretical and clinical issues remain, including a definition of the term "remission", its characteristics and types as well as approaches to optimal tactics of "symptomatic" and "pathogenetic" drug therapy at different stages of the disease. Use of a such tactics will allow to induce quickly a state of remission and maintain it for a long term. Further research is needed which should be directed to investigation of a heterogeneity of RA pathogenetic mechanisms and to elaboration of approaches to its early diagnosis as well as to improving methods for monitoring a disease activity, biomarkers of efficacy and resistance to therapy, and finally, to developing of a differentiated therapy, including a search for new "therapeutic" targets.