Global, regional and national temporal trends in prevalence for musculoskeletal disorders in women of childbearing age, 1990-2019: an age-period-cohort analysis based on the Global Burden of Disease Study 2019.

OBJECTIVES: To provide an overview and in-depth analysis of temporal trends in prevalence of musculoskeletal (MSK) disorders in women of childbearing age (WCBA) at global, regional and national levels over the last 30 years, with a special focus on their associations with age, period and birth cohort. METHODS: Estimates and 95% uncertainty intervals (UIs) for MSK disorders prevalence in WCBA were extracted from the Global Burden of Diseases, Injuries and Risk Factors Study 2019. An age-period-cohort model was adopted to estimate the overall annual percentage change of prevalence (net drift, % per year), annual percentage change of prevalence within each age group (local drift, % per year), fitted longitudinal age-specific rates adjusted for period deviations (age effects) and period/cohort relative risks (period/cohort effects) from 1990 to 2019. RESULTS: In 2019, the global number of MSK disorders prevalence in WCBA was 354.57 million (95% UI: 322.64 to 387.68). Fifty countries had at least one million prevalence, with India, China, the USA, Indonesia and Brazil being the highest accounting for 51.03% of global prevalence. From 1990 to 2019, a global net drift of MSK disorders prevalence in WCBA was -0.06% (95% CI: -0.07% to -0.05%) per year, ranging from -0.09% (95% CI: -0.10% to -0.07%) in low-middle sociodemographic index (SDI) region to 0.10% (95% CI: 0.08% to 0.12%) in high-middle SDI region, with 138 countries presenting increasing trends, 24 presenting decreasing trends and 42 presenting relatively flat trends. As reflected by local drift, higher SDI regions had more age groups showing rising prevalence whereas lower SDI regions had more declining prevalence. Globally, an increasing occurrence of MSK disorders prevalence in WCBA beyond adolescent and towards the adult stage has been prominent. Age effects illustrated similar patterns across different SDI regions, with risk increasing with age. High SDI region showed generally lower period risks over time, whereas others showed more unfavourable period risks. High, high-middle and middle SDI regions presented unfavourable prevalence deteriorations, whereas others presented favourable prevalence improvements in successively birth cohorts. CONCLUSIONS: Although a favourable overall temporal trend (net drift) of MSK disorders prevalence in WCBA was observed over the last 30 years globally, there were 138 countries showing unfavourable rising trends, coupled with deteriorations in period/cohort risks in many countries, collectively raising concerns about timely realisation of the Targets of Sustainable Development Goal. Improvements in the MSK disorders-related prevention, management and treatment programmes in WCBA could decline the relative risk for successively younger birth cohorts and for all age groups over period progressing.

Journey through discovery of 75 years glucocorticoids: evolution of our knowledge of glucocorticoid receptor mechanisms in rheumatic diseases.

For three-quarters of a century, glucocorticoids (GCs) have been used to treat rheumatic and autoimmune diseases. Over these 75 years, our understanding of GCs binding to nuclear receptors, mainly the glucocorticoid receptor (GR) and their molecular mechanisms has changed dramatically. Initially, in the late 1950s, GCs were considered important regulators of energy metabolism. By the 1970s/1980s, they were characterised as ligands for hormone-inducible transcription factors that regulate many aspects of cell biology and physiology. More recently, their impact on cellular metabolism has been rediscovered. Our understanding of cell-type-specific GC actions and the crosstalk between various immune and stromal cells in arthritis models has evolved by investigating conditional GR mutant mice using the Cre/LoxP system. A major achievement in studying the complex, cell-type-specific interplay is the recent advent of omics technologies at single-cell resolution, which will provide further unprecedented insights into the cell types and factors mediating GC responses. Alongside gene-encoded factors, anti-inflammatory metabolites that participate in resolving inflammation by GCs during arthritis are just being uncovered. The translation of this knowledge into therapeutic concepts will help tackle inflammatory diseases and reduce side effects. In this review, we describe major milestones in preclinical research that led to our current understanding of GC and GR action 75 years after the first use of GCs in arthritis.

Abatacept and non-melanoma skin cancer in patients with rheumatoid arthritis: a comprehensive evaluation of randomised controlled trials and observational studies.

OBJECTIVES: This study aims to evaluate non-melanoma skin cancer (NMSC) risk associated with abatacept treatment for rheumatoid arthritis (RA). METHODS: This evaluation included 16 abatacept RA clinical trials and 6 observational studies. NMSC incidence rates (IRs)/1000 patient-years (p-y) of exposure were compared between patients treated with abatacept versus placebo, conventional synthetic (cs) disease-modifying antirheumatic drugs (DMARDs) and other biological/targeted synthetic (b/ts)DMARDs. For observational studies, a random-effects model was used to pool rate ratios (RRs). RESULTS: ~49 000 patients receiving abatacept were analysed from clinical trials (~7000) and observational studies (~42 000). In randomised trials (n=4138; median abatacept exposure, 12 (range 2-30) months), NMSC IRs (95% CIs) were not significantly different for abatacept (6.0 (3.3 to 10.0)) and placebo (4.0 (1.3 to 9.3)) and remained stable throughout the long-term, open-label period (median cumulative exposure, 28 (range 2-130 months); 21 335 p-y of exposure (7044 patients over 3 years)). For registry databases, NMSC IRs/1000 p-y were 5-12 (abatacept), 1.6-10 (csDMARDs) and 3-8 (other b/tsDMARDs). Claims database IRs were 19-22 (abatacept), 15-18 (csDMARDs) and 14-17 (other b/tsDMARDs). Pooled RRs (95% CIs) from observational studies for NMSC in patients receiving abatacept were 1.84 (1.00 to 3.37) vs csDMARDs and 1.11 (0.98 to 1.26) vs other b/tsDMARDs. CONCLUSIONS: Consistent with the warnings and precautions of the abatacept label, this analysis suggests a potential increase in NMSC risk with abatacept use compared with csDMARDs. No significant increase was observed compared with b/tsDMARDs, but the lower limit of the 95% CI was close to unity.

Initial glucocorticoid bridging in rheumatoid arthritis: does it affect glucocorticoid use over time?

OBJECTIVES: To compare the use of glucocorticoids (GC) over time in patients with rheumatoid arthritis (RA) who were or were not treated initially with GC bridging therapy. METHODS: Data from the BeSt, CareRA and COBRA trials were combined in an individual patient data (IPD) meta-analysis. We compared GC use between bridgers and non-bridgers at 12, 18 and 24 months from baseline with mixed-effects regression analysis. Secondary outcomes were mean cumulative GC dose until 24 months after baseline with and without the bridging period, Disease Activity Score based on 28 joints (DAS28) over time and number of disease-modifying antirheumatic drug (DMARD) changes. RESULTS: 252/625 patients (40%) were randomised to GC bridging (bridgers). Excluding the period of bridging, later GC use was low in both groups and cumulative doses were similar. Mean DAS28 was similar between the groups, but bridgers improved more rapidly (p<0.001) in the first 6 months and the bridgers required significantly fewer changes in DMARDs (incidence rate ratio 0.59 (95% CI 0.38 to 0.94)). GC use was higher in the bridgers at t=12 months (OR 3.27 (95% CI 1.06 to 10.08)) and the bridging schedules resulted in a difference in cumulative GC dose of 2406 mg (95% CI 1403 to 3408) over 24 months. CONCLUSION: In randomised trials comparing GC bridging and no GC bridging, bridgers had a more rapid clinical improvement, fewer DMARD changes and similar late use of GC compared with non-bridgers. GC bridging per protocol resulted, as could be expected, in a higher cumulative GC dose over 2 years.

NAT10 promotes synovial aggression by increasing the stability and translation of N4-acetylated PTX3 mRNA in rheumatoid arthritis.

OBJECTIVE: Recent studies indicate that N-acetyltransferase 10 (NAT10)-mediated ac4C modification plays unique roles in tumour metastasis and immune infiltration. This study aimed to uncover the role of NAT10-mediated ac4C in fibroblast-like synoviocytes (FLSs) functions and synovial immune cell infiltration in rheumatoid arthritis (RA). METHODS: FLSs were obtained from active established patients with RA. Protein expression was determined by western blotting or immunohistochemistry or multiplexed immunohistochemistry. Cell migration was measured using a Boyden chamber. ac4C-RIP-seq combined with RNA-seq was performed to identify potential targets of NAT10. RNA immunoprecipitation was used to validate the interaction between protein and mRNA. NAT10 haploinsufficiency, inhibitor remodelin or intra-articular Adv-NAT10 was used to suppress arthritis in mice with delayed-type hypersensitivity arthritis (DYHA) and collagen II-induced arthritis (CIA) and rats with CIA. RESULTS: We found elevated levels of NAT10 and ac4C in FLSs and synovium from patients with RA. NAT10 knockdown or specific inhibitor treatment reduced the migration and invasion of RA FLSs. Increased NAT10 level in the synovium was positively correlated with synovial infiltration of multiple types of immune cells. NAT10 inhibition in vivo attenuated the severity of arthritis in mice with CIA and DTHA, and rats with CIA. Mechanistically, we explored that NAT10 regulated RA FLS functions by promoting stability and translation efficiency of N4-acetylated PTX3 mRNA. PTX3 also regulated RA FLS aggression and is associated with synovial immune cell infiltration. CONCLUSION: Our findings uncover the important roles of NAT10-mediated ac4C modification in promoting rheumatoid synovial aggression and inflammation, indicating that NAT10 may be a potential target for the treatment of RA, even other dysregulated FLSs-associated disorders.

Disease activity of rheumatoid arthritis and kidney function decline: a large prospective registry study.

INTRODUCTION: Chronic kidney disease (CKD) is a common comorbidity of rheumatoid arthritis (RA). The association of longitudinal RA disease activity with long-term kidney function has remained uncertain. METHOD: We analysed a multicentre prospective RA registry in the USA from 2001 to 2022. The exposure was updated time-averaged Clinical Disease Activity Index (TA-CDAI) categories from study enrolment. The primary outcome was a longitudinal estimated glomerular filtration rate (eGFR) change. Secondary outcomes included developments of CKD stage G3a (eGFR<60 mL/min/1.73 m2) and stage G3b (eGFR<45 mL/min/1.73 m2). Results were adjusted for relevant time-fixed and time-varying covariates. RESULTS: 31 129 patients (median age: 58.0 years, female: 76.3%, median eGFR: 90.7 mL/min/1.73 m2) contributed 234 973 visits and 146 778 person-years of follow-up. Multivariable mixed-effect linear model showed an average annual eGFR decline during follow-up in the TA-CDAI-remission group of -0.83 mL/min/1.73 m2 and estimated additional annual declines (95% CI) of -0.09 (-0.15 to -0.03) in low, -0.17 (-0.23 to -0.10) in moderate and -0.18 (-0.27 to -0.08) mL/min/1.73 m2 in high disease activity patients. Compared with TA-CDAI remission, adjusted HRs (95% CI) for CKD stage G3a during follow-up were 1.15 (1.01 to 1.30) in low, 1.22 (1.06 to 1.40) in moderate and 1.27 (1.05 to 1.52) in high disease activity; for CKD stage G3b, 1.22 (0.84 to 1.76) in low, 1.66 (1.12 to 2.45) in moderate and 1.93 (1.16 to 3.20) in high disease activity. CONCLUSIONS: Higher RA disease activity was associated with accelerated eGFR decline and increased risk of clinically relevant kidney dysfunction. Future intervention studies should attempt to replicate the association between RA disease activity and eGFR.

Positive feedback loop PU.1-IL9 in Th9 promotes rheumatoid arthritis development.

OBJECTIVES: T helper 9 (Th9) cells are recognised for their characteristic expression of the transcription factor PU.1 and production of interleukin-9 (IL-9), which has been implicated in various autoimmune diseases. However, its precise relationship with rheumatoid arthritis (RA) pathogenesis needs to be further clarified. METHODS: The expression levels of PU.1 and IL-9 in patients with RA were determined by ELISA, western blotting (WB) and immunohistochemical staining. PU.1-T cell-conditional knockout (KO) mice, IL-9 KO and IL-9R KO mice were used to establish collagen antibody-induced arthritis (CAIA), respectively. The inhibitor of PU.1 and IL-9 blocking antibody was used in collagen-induced arthritis (CIA). In an in vitro study, the effects of IL-9 were investigated using siRNAs and IL-9 recombinant proteins. Finally, the underlying mechanisms were further investigated by luciferase reporter analysis, WB and Chip-qPCR. RESULTS: The upregulation of IL-9 expression in patients with RA exhibited a positive correlation with clinical markers. Using CAIA and CIA model, we demonstrated that interventions targeting PU.1 and IL-9 substantially mitigated the inflammatory phenotype. Furthermore, in vitro assays provided the proinflammatory role of IL-9, particularly in the hyperactivation of macrophages and fibroblast-like synoviocytes. Mechanistically, we uncovered that PU.1 and IL-9 form a positive feedback loop in RA: (1) PU.1 directly binds to the IL-9 promoter, activating its transcription and (2) Th9-derived IL-9 induces PU.1 via the IL-9R-JAK1/STAT3 pathway. CONCLUSIONS: These results support that the PU.1-IL-9 axis forms a positive loop in Th9 dysregulation of RA. Targeting this signalling axis presents a potential target approach for treating RA.

Integrated safety analysis of filgotinib in patients with moderate-to-severe rheumatoid arthritis over a treatment duration of up to 8.3 years.

OBJECTIVES: To update the long-term safety profile of filgotinib, a Janus kinase-1 preferential inhibitor, in patients with moderate-to-severe rheumatoid arthritis. METHODS: Data from seven trials were integrated (NCT01888874, NCT01894516, NCT02889796, NCT02873936, NCT02886728, NCT02065700 and NCT03025308). Patients received once-daily filgotinib 100 mg or 200 mg. Exposure-adjusted incidence rates (EAIRs)/100 patient-years of exposure (PYE) were calculated for treatment-emergent adverse events (TEAEs). Post hoc analyses assessed patients aged <65 and ≥65 years. RESULTS: Patients (N=3691) received filgotinib for a median (maximum) of 3.8 (8.3) years (12 541 PYE). Rates of TEAEs of interest: serious infections, malignancies, major adverse cardiovascular events (MACE) and venous thromboembolism were stable over time and comparable between doses. In the overall population, numerically lower EAIR (95% CI)/100 PYE of herpes zoster was observed for filgotinib 100 mg versus 200 mg (1.1 (0.8 to 1.5) vs 1.5 (1.2 to 1.8)). Incidence of serious infections, herpes zoster, MACE, malignancies and all-cause mortality was higher in patients aged ≥65 versus <65 years. In patients aged ≥65 years, EAIRs (95% CI)/100 PYE for non-melanoma skin cancer (NMSC) (0.4 (0.1 to 1.1) vs 1.4 (0.8 to 2.2)), malignancies excluding NMSC (1.0 (0.5 to 1.9) vs 2.0 (1.3 to 2.9)) and all-cause mortality (1.3 (0.7 to 2.2) vs 1.6 (1.0 to 2.5)) were numerically lower for filgotinib 100 mg versus 200 mg. CONCLUSIONS: In the overall population, TEAEs of interest were stable over time and similar between filgotinib 100 mg and 200 mg dose groups, except for herpes zoster. A dose-dependent relationship between malignancies and all-cause mortality was suggested in patients ≥65 years old.

Olokizumab plus methotrexate: safety and efficacy over 106 weeks of treatment.

OBJECTIVE: To report long-term safety and tolerability of olokizumab (OKZ) in combination with methotrexate (MTX) in subjects with active rheumatoid arthritis (RA), using pooled data from three randomised clinical trials (RCT) followed by open-label extension (OLE) study. METHODS: Cumulative data from three phase 3 core trials and their OLE were analysed. Safety variables assessed included treatment-emergent adverse events (AEs), serious AEs (SAEs), AEs of special interest and laboratory results. Efficacy assessments included ACR20/50/70 responses, Disease Activity Score 28 (C-reactive protein) <3.2, CDAI remission and low disease activity (LDA), SDAI remission and LDA, HAQ-DI decrease of 0.22 unit and Boolean 2.0 remission. RESULTS: A total of 2304 patients received OKZ in combination with MTX either once every 2 weeks or once every 4 weeks. Event rates per 100 patient-years in OKZ every 2 weeks and OKZ every 4 weeks, respectively, were 9.57 and 9.13 for SAEs; 2.95 and 2.34 for serious infections; 0.09 and 0.05 for gastrointestinal perforations; 0.58 and 0.83 for major adverse cardiovascular events; and 0.45 and 0.50 for malignancies. No increase in the rate of any AE was observed over 106 weeks of treatment. The evaluation of laboratory variables demonstrated the expected changes, like neutropenia, elevation of liver enzymes and blood lipids. Clinical response rates remained stable during the OLE. CONCLUSION: The long-term safety and tolerability of OKZ in combination with MTX remained stable. The efficacy of OKZ was maintained through week 106. These findings support OKZ as a treatment option for patients with active RA.

EPO promotes the progression of rheumatoid arthritis by inducing desialylation via increasing the expression of neuraminidase 3.

OBJECTIVE: Erythropoietin (EPO) known as an erythrocyte-stimulating factor is increased in patients with rheumatoid arthritis (RA). Nevertheless, the function of EPO in the process of RA and relative mechanism needs to be further clarified. METHODS: The level of EPO in serum and synovial fluid from patients with RA and healthy controls was determined by . Collagen-induced arthritis (CIA) mice were constructed to confirm the role of EPO on RA pathogenesis. Differentially expressed genes (DEGs) of EPO-treated fibroblast-like synoviocyte (FLS) were screened by transcriptome sequencing. The transcription factor of neuraminidase 3 (NEU3) of DEGs was verified by double luciferase reporting experiment, DNA pulldown, electrophoretic mobility shift assay and chromatin immunoprecipitation-quantitative PCR (qPCR) assay. RESULTS: The overexpression of EPO was confirmed in patients with RA, which was positively associated with Disease Activity Score 28-joint count. Additionally, EPO intervention could significantly aggravate the joint destruction in CIA models. The upregulation of NEU3 was screened and verified by transcriptome sequencing and qPCR in EPO-treated FLS, and signal transducer and activator of transcription 5 was screened and verified to be the specific transcription factor of NEU3. EPO upregulates NEU3 expression via activating the Janus kinase 2 (JAK2)-STAT5 signalling pathway through its receptor EPOR, thereby to promote the desialylation through enhancing the migration and invasion ability of FLS, which is verified by JAK2 inhibitor and NEU3 inhibitor. CONCLUSION: EPO, as a proinflammatory factor, accelerates the process of RA through transcriptional upregulation of the expression of NEU3 by JAK2/STAT5 pathway.

Evaluation of discontinuation for adverse events of JAK inhibitors and bDMARDs in an international collaboration of rheumatoid arthritis registers (the 'JAK-pot' study).

BACKGROUND: In a clinical trial setting, patients with rheumatoid arthritis (RA) taking the Janus kinase inhibitor (JAKi) tofacitinib demonstrated higher adverse events rates compared with those taking the tumour necrosis factor inhibitors (TNFi) adalimumab or etanercept. OBJECTIVE: Compare treatment discontinuations for adverse events (AEs) among second-line therapies in an international real-world RA population. METHODS: Patients initiating JAKi, TNFi or a biological with another mode of action (OMA) from 17 registers participating in the 'JAK-pot' collaboration were included. The primary outcome was the rate of treatment discontinuation due to AEs. We used unadjusted and adjusted cause-specific Cox proportional hazard models to compare treatment discontinuations for AEs among treatment groups by class, but also evaluating separately the specific type of JAKi. RESULTS: Of the 46 913 treatment courses included, 12 523 were JAKi (43% baricitinib, 40% tofacitinib, 15% upadacitinib, 2% filgotinib), 23 391 TNFi and 10 999 OMA. The adjusted cause-specific hazard rate of treatment discontinuation for AEs was similar for TNFi versus JAKi (1.00, 95% CI 0.92 to 1.10) and higher for OMA versus JAKi (1.11, 95% CI 1.01 to 1.23), lower with TNFi compared with tofacitinib (0.81, 95% CI 0.71 to 0.90), but higher for TNFi versus baricitinib (1.15, 95% CI 1.01 to 1.30) and lower for TNFi versus JAKi in patients 65 or older with at least one cardiovascular risk factor (0.79, 95% CI 0.65 to 0.97). CONCLUSION: While JAKi overall were not associated with more treatment discontinuations for AEs, subgroup analyses suggest varying patterns with specific JAKi, such as tofacitinib, compared with TNFi. However, these observations should be interpreted cautiously, given the observational study design.

Rheuma-VOR study: optimising healthcare of rheumatic diseases by multiprofessional coordinating centres.

OBJECTIVES: Early diagnosis of inflammatory arthritis is critical to prevent joint damage and functional incapacities. However, the discrepancy between recommendations of early diagnosis and reality is remarkable. The Rheuma-VOR study aimed to improve the time to diagnosis of patients with early arthritis by coordinating cooperation between primary care physicians, specialists and patients in Germany. METHODS: This prospective non-randomised multicentre study involved 2340 primary care physicians, 72 rheumatologists, 4 university hospitals and 4 rheumatology centres in 4 German Federal States. The two coprimary endpoints (time to diagnosis and screening performance of primary care physicians) were evaluated for early versus late implementation phase. Additionally, time to diagnosis and secondary endpoints (decrease of disease activity, increase in quality of life and overall well-being, improvement of fatigue, depression, functional ability, and work ability, reduction in drug and medical costs and hospitalisation) were compared with a reference cohort of the German Rheumatism Research Centre (DRFZ) reflecting standard care. RESULTS: A total of 7049 patients were enrolled in the coordination centres and 1537 patients were diagnosed with a rheumatic disease and consented to further participation. A follow-up consultation after 1 year was realised in 592 patients. The time to diagnosis endpoint and the secondary endpoints were met. In addition, the calculation of cost-effectiveness shows that Rheuma-VOR has a dominant cost-benefit ratio compared with standard care. DISCUSSION: Rheuma-VOR has shown an improvement in rheumatological care, patient-reported outcome parameters and cost savings by coordinating the cooperation of primary care physicians, rheumatologists and patients, in a nationwide approach.

Determination of the most appropriate ACR response definition for contemporary drug approval trials in rheumatoid arthritis.

OBJECTIVES: To evaluate which American College of Rheumatology (ACR) response definition (ACR20, 50 or 70) should primarily be used for efficacy claims in future drug approval trials of rheumatoid arthritis (RA). METHODS: We systematically searched EMBASE, Medline and the Cochrane Library for randomised controlled RA drug approval trials of biological and targeted synthetic disease-modifying antirheumatic drugs (DMARDs). We included full-text articles reporting ACR response rates for multiple time points over a 24-week placebo-controlled period and visualised normalised response trajectories over time in different patient populations. Using mixed-effect logistic regression, we calculated the proportion of ACR responders per outcome and time point, and compared the discriminant validity of these metrics at multiple time points. RESULTS: We screened 12 680 records and included 45 in the final analysis. Discriminative capacity of the ACR20 was high across all time points, whereas ACR50 and ACR70 showed highest discrimination towards the end of the placebo-controlled periods. This effect could be observed in all patient populations and compound groups. Faster response to treatment was observed in DMARD naïve patient populations when compared with DMARD insufficient responders. CONCLUSION: ACR20 remains the most powerful discriminator between active treatment and placebo, especially when early discrimination is of primary interest. At the same time, our results support the selection of more stringent thresholds if later time points shall be evaluated, given their comparable discriminant but higher clinical face validity.

Single-cell resolution of longitudinal blood transcriptome profiles in rheumatoid arthritis, systemic lupus erythematosus and healthy control pregnancies.

OBJECTIVES: Comparative longitudinal analyses of cellular composition and peripheral blood gene expression in Rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and healthy pregnancies. METHODS: In total, 335 whole blood samples from 84 RA, SLE and healthy controls before pregnancy, at each trimester, 6 weeks, 6 months and 12 months post partum were analysed. We combined bulk and single cell RNA analyses for cell-type estimation, validated by flow cytometry, before combining this in a cell-type adjusted analysis for an improved resolution of unrecognised gene expression changes associated with RA and SLE pregnancies. RESULTS: Patients were well regulated throughout pregnancy, and few had pregnancy complications. In SLE, the interferon signature was augmented during pregnancy, and the pregnancy signature was continued post partum. An altered cell type composition strongly influences the profile. In the pregnancy signature, transcripts involved in galactosylation potentially altering the effector functions of autoantibodies became more evident. Several genes in the adjusted RA signature are expressed in mucosal associated invariant T cells. CONCLUSION: We found distinct RA, SLE and pregnancy signatures, and no expression patterns could be attributed to medication or disease activity. Our results support the need for close postpartum follow-up of patients with SLE. Gene expression patterns in RA were closer to healthy controls than to SLE, and primarily became evident after cell-type adjustment. Adjusting for cell abundance unravelled gene expression signatures less associated with variation in cell-composition and highlighted genes with expression profiles associated with changes in specialised cell populations.

Expression quantitative trait loci analysis in rheumatoid arthritis identifies tissue specific variants associated with severity and outcome.

OBJECTIVE: Genome-wide association studies have successfully identified more than 100 loci associated with susceptibility to rheumatoid arthritis (RA). However, our understanding of the functional effects of genetic variants in causing RA and their effects on disease severity and response to treatment remains limited. METHODS: In this study, we conducted expression quantitative trait locus (eQTL) analysis to dissect the link between genetic variants and gene expression comparing the disease tissue against blood using RNA-Sequencing of synovial biopsies (n=85) and blood samples (n=51) from treatment-naïve patients with RA from the Pathobiology of Early Arthritis Cohort. RESULTS: This identified 898 eQTL genes in synovium and genes loci in blood, with 232 genes in common to both synovium and blood, although notably many eQTL were tissue specific. Examining the HLA region, we uncovered a specific eQTL at HLA-DPB2 with the critical triad of single-nucleotide polymorphisms (SNPs) rs3128921 driving synovial HLA-DPB2 expression, and both rs3128921 and HLA-DPB2 gene expression correlating with clinical severity and increasing probability of the lympho-myeloid pathotype. CONCLUSIONS: This analysis highlights the need to explore functional consequences of genetic associations in disease tissue. HLA-DPB2 SNP rs3128921 could potentially be used to stratify patients to more aggressive treatment immediately at diagnosis.

Inflammatory tissue priming: novel insights and therapeutic opportunities for inflammatory rheumatic diseases.

Due to optimised treatment strategies and the availability of new therapies during the last decades, formerly devastating chronic inflammatory diseases such as rheumatoid arthritis or systemic sclerosis (SSc) have become less menacing. However, in many patients, even state-of-the-art treatment cannot induce remission. Moreover, the risk for flares strongly increases once anti-inflammatory therapy is tapered or withdrawn, suggesting that underlying pathological processes remain active even in the absence of overt inflammation. It has become evident that tissues have the ability to remember past encounters with pathogens, wounds and other irritants, and to react more strongly and/or persistently to the next occurrence. This priming of the tissue bears a paramount role in defence from microbes, but on the other hand drives inflammatory pathologies (the Dr Jekyll and Mr Hyde aspect of tissue adaptation). Emerging evidence suggests that long-lived tissue-resident cells, such as fibroblasts, macrophages, long-lived plasma cells and tissue-resident memory T cells, determine inflammatory tissue priming in an interplay with infiltrating immune cells of lymphoid and myeloid origin, and with systemically acting factors such as cytokines, extracellular vesicles and antibodies. Here, we review the current state of science on inflammatory tissue priming, focusing on tissue-resident and tissue-occupying cells in arthritis and SSc, and reflect on the most promising treatment options targeting the maladapted tissue response during these diseases.

Janus kinase inhibitors and tumour necrosis factor inhibitors show a favourable safety profile and similar persistence in rheumatoid arthritis, psoriatic arthritis and spondyloarthritis: real-world data from the BIOBADASER registry.

OBJECTIVES: To compare the safety of Janus kinase inhibitors (JAKi) with that of tumour necrosis factor inhibitors (TNFi) and determine drug persistence among patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA). METHODS: We analysed data from patients included in BIOBADASER 3.0 and treated with JAKi or TNFi from 2015 to 2023 and estimated the incidence rate ratio (IRR) of adverse events and persistence. RESULTS: A total of 6826 patients were included. Of these, 52% had RA, 25% psoriatic arthritis and 23% axial SpA. Treatment was with TNFi in 86%. The mean duration of treatment was 2.2±2.0 years with TNFi versus 1.8±1.5 with JAKi. JAKis were prescribed in older patients with longer term disease, greater comorbidity and later treatment lines and more frequently as monotherapy. The IRR of all infections and gastrointestinal events was higher among patients with RA treated with JAKi. Drug persistence at 1, 2 and 3 years was 69%, 55% and 45% for TNFi and 68%, 54% and 45% for JAKi. Multivariate regression models showed a lower probability of discontinuation for JAKi (HR=0.85; 95% CI 0.78-0.92) and concomitant conventional synthetic disease-modifying antirheumatic drugs (HR=0.90; 95% CI 0.84-0.96). The risk of discontinuation increased with glucocorticoids, comorbidities, greater disease activity and later treatment lines. CONCLUSIONS: Infections, herpes zoster and gastrointestinal adverse events in patients with RA tended to be more frequent with JAKi. However, prognosis was poor in patients receiving JAKi. Persistence was similar for TNFi and JAKi, although factors associated with discontinuation differed by diagnostic group.

Helicobacter pylori upregulates PAD4 expression via stabilising HIF-1α to exacerbate rheumatoid arthritis.

OBJECTIVE: Helicobacter pylori infection has been reported to aggravate rheumatoid arthritis (RA), but the relevant mechanism remains unclear. This study aimed to investigate the underlying pathogenic mechanism of H. pylori infection in the progression of RA. METHODS: The Disease Activity Score (DAS-28) and serum anticitrullinated protein antibody (ACPA) levels were compared between H. pylori-negative and H. pylori-positive patients with RA. MH7A cells were stimulated with polyclonal ACPA purified from the peripheral blood of patients with RA. The citrullination levels were assessed by western blot in GES-1 cells and sera. ChIP, luciferase reporter assays, mass spectrometry and ELISA were applied to explore the molecular mechanism of H. pylori infection in RA progression. RESULTS: The DAS-28 and ACPA levels of patients with RA in the H. pylori-positive group were significantly higher than those in the H. pylori-negative group. Polyclonal ACPA derived from H. pylori-positive patients promoted cell proliferation and induced secretion of IL-6 and IL-8. For the first time, we found that H. pylori infection induces cellular protein citrullination by upregulating protein arginine deiminase type 4 (PAD4). Furthermore, we confirmed a direct functional binding of hypoxia-inducible factor 1α on the PADI4 gene promoter. We demonstrated that PAD4 interacts with and citrullinates keratin 1 (K1), and serum and synovial fluid levels of anti-Cit-K1 antibody were markedly increased in H. pylori-infected patients with RA. CONCLUSION: Our findings reveal a novel mechanism by which H. pylori infection contributes to RA progression. Therapeutic interventions targeting H. pylori may be a viable strategy for the management of RA.

Expression of HIF1α in intestinal epithelium restricts arthritis inflammation by inhibiting RIPK3-induced cell death machinery.

OBJECTIVES: To investigate the mechanism by which intestinal epithelial cell (IEC) death induces arthritis. METHODS: IEC death was assessed by staining for necroptosis and apoptosis markers and fluorescence in situ hybridisation at different time points during collagen-induced arthritis (CIA). During the development of CIA, messenger RNA (mRNA) sequencing was performed, followed by Gene Ontology enrichment analysis of differentially expressed genes. Mice deficient for hypoxia-inducible factor 1α (Hif1a) in IECs (Hif1a ∆IEC) were generated and induced for arthritis. mRNA sequencing, chromatin immunoprecipitated (ChIP) DNA sequencing and ChIP-qualitative PCR were performed on IECs from Hif1a ∆IEC mice and littermate controls. Effects of HIF1α stabilisation by inhibition of prolyl hydroxylase domain-containing enzymes and treatment with the inhibitor of receptor-interacting protein kinase-3 (RIPK3) were tested in intestinal organoids and in CIA. RESULTS: IEC underwent apoptotic and necroptotic cell death at the onset of arthritis, leading to impaired gut barrier function. HIF1α was identified as one of the most upregulated genes in IECs during the onset of arthritis. Deletion of Hif1a in IEC enhanced IEC necroptosis, triggered intestinal inflammation and exacerbated arthritis. HIF1α was found to be a key transcriptional repressor for the necroptosis-inducing factor RIPK3. Enhanced RIPK3 expression, indicating necroptosis, was also found in the intestinal epithelium of patients with new-onset rheumatoid arthritis. Therapeutic stabilisation of HIF1α as well as small-molecule-based RIPK3 inhibition rescued intestinal necroptosis in vitro and in vivo and suppressed the development of arthritis. CONCLUSION: Our results identify IEC necroptosis as a critical link between the gut and the development of arthritis.

Male patients with inflammatory joint diseases are less likely than controls to be childless: results from a Norwegian population-based cohort study of 10 865 patients.

OBJECTIVES: To investigate the number of children per man and the proportion of childless men as a proxy of fertility in a national cohort of men with inflammatory joint diseases (IJDs), compared with matched controls from the general population. METHODS: This is a nationwide, population-based retrospective cohort study. Male patients with IJDs (n = 10 865) in the Norwegian Arthritis Registry were individually matched 1:5 on birth year and county of residence with men without IJDs obtained from the National Population Register (n = 54 325). Birth data were obtained from the Medical Birth Registry of Norway. We compared the mean number of children per man and the proportion of childless men and analysed the impact of age and year of diagnosis. RESULTS: The mean number of children per man in the patient group was 1.80 versus 1.69 in the comparison group (p <0.001), and 21% of the patients in the patient group were childless versus 27% in the comparison group (p <0.001). The finding of less childlessness and higher number of children per man remained consistent across age at diagnosis, except for those diagnosed at age 0-19 years. The difference in childlessness was most pronounced for men diagnosed after year 2000, especially when diagnosed at 30-39 years of age (22% vs 32%, p<0.001). CONCLUSION: In this large cohort study we found that patients with IJD have a higher number of children and are less likely to be childless compared with controls. Factors associated with developing or having an IJD might influence fertility and this requires further investigation.