Association between IL-33 and other inflammatory factors in patients with rheumatoid arthritis and in fibroblast-like synoviocytes in vitro

Redefinition of Synovial Fibroblasts in Rheumatoid Arthritis

The breakdown of immune tolerance and the rise in autoimmunity contribute to the onset of rheumatoid arthritis (RA), driven by significant changes in immune components. Recent advances in single-cell and spatial transcriptome profiling have revealed shifts in cell distribution and composition, expanding our understanding beyond molecular-level changes in inflammatory cytokines, autoantibodies, and autoantigens in RA. Surprisingly, synovial fibroblasts (SFs) play an active immunopathogenic role rather than remaining passive bystanders in RA, with notable alterations in their subpopulation distribution and composition. This study examines these changes in SF heterogeneity, assesses their impact on RA progression, and elucidates the immune characteristics and functions of SF subsets in the RA autoimmunity, encompassing both intrinsic and adaptive immunity. Additionally, this review discusses therapeutic strategies targeting immune SF subsets, highlighting the potential of future interventions in SF phenotypic reprogramming. Overall, this review redefines the role of SFs in RA and suggests targeting SF phenotypic reprogramming and its upstream molecules as a promising therapeutic approach to restore immune balance and modulate immune tolerance in RA.

The Role of Alarmins in the Pathogenesis of Rheumatoid Arthritis, Osteoarthritis, and Psoriasis

Alarmins are immune-activating factors released after cellular injury or death. By secreting alarmins, cells can interact with immune cells and induce a variety of inflammatory responses. The broad family of alarmins involves several members, such as high-mobility group box 1, S100 proteins, interleukin-33, and heat shock proteins, among others. Studies have found that the concentrations and expression profiles of alarmins are altered in immune-mediated diseases. Furthermore, they are involved in the pathogenesis of inflammatory conditions. The aim of this narrative review is to present the current evidence on the role of alarmins in rheumatoid arthritis, osteoarthritis, and psoriasis. We discuss their potential involvement in mechanisms underlying the progression of these diseases and whether they could become therapeutic targets. Moreover, we summarize the impact of pharmacological agents used in the treatment of these diseases on the expression of alarmins.

Causal association between sleep traits and autoimmune arthritis: Evidence from a bidirectional Mendelian randomization study

OBJECTIVE

To explore whether there is a genetic causal relationship between sleep traits and the risk of autoimmune arthritis (AA).

METHODS

Univariable and multivariable Mendelian randomization was employed using genome-wide association studies data to assess sleep traits' associations with AAs, including rheumatoid arthritis (RA), ankylosing spondylitis, and psoriatic arthritis. The inverse-variance weighted method served as the primary analysis, supplemented by the CAUSE method to improve power and mitigate false positives. Mediation Mendelian randomization was used to quantify direct and indirect effects.

RESULTS

Significant associations were shown between insomnia symptoms and increased risk of overall RA (odds ratio = 2.75, 95% confidence interval 1.45-5.22) and seronegative RA (odds ratio = 6.95, 95% confidence interval 2.47-19.56). CAUSE results revealed an association of insomnia symptoms with overall RA and seronegative RA, as well as the sleep duration with overall RA. After the adjustment for body mass index, alcohol status, smoking status, and physical activity levels, multivariable analyses revealed that genetic predisposition to insomnia symptoms and prolonged sleep duration showed independent negative associations with the risk of overall RA and seropositive RA. In the reversed multivariable analyses, a borderline negative association was shown in the overall RA-sleep duration and a positive association of seropositive RA with the risk of insomnia symptoms.

CONCLUSION

This study demonstrated a potential bidirectional causal relationship that genetic predisposition to insomnia symptoms and shorter sleep duration was associated with the risk of AA, especially RA. Genetic predisposition to RA was also associated with decreased sleep duration, as well as increased insomnia symptom risk.

Distinct fibroblast functions associated with fibrotic and immune-mediated inflammatory diseases and their implications for therapeutic development

Fibroblasts are ubiquitous cells that can adopt many functional states. As tissue-resident sentinels, they respond to acute damage signals and shape the earliest events in fibrotic and immune-mediated inflammatory diseases. Upon sensing an insult, fibroblasts produce chemokines and growth factors to organize and support the response. Depending on the size and composition of the resulting infiltrate, these activated fibroblasts may also begin to contract or relax thus changing local stiffness within the tissue. These early events likely contribute to the divergent clinical manifestations of fibrotic and immune-mediated inflammatory diseases. Further, distinct changes to the cellular composition and signaling dialogue in these diseases drive progressive fibroblasts specialization. In fibrotic diseases, fibroblasts support the survival, activation and differentiation of myeloid cells, granulocytes and innate lymphocytes, and produce most of the pathogenic extracellular matrix proteins. Whereas, in immune-mediated inflammatory diseases, sequential accumulation of dendritic cells, T cells and B cells programs fibroblasts to support local, destructive adaptive immune responses. Fibroblast specialization has clear implications for the development of effective induction and maintenance therapies for patients with these clinically distinct diseases.

Potential mechanistic roles of Interleukin-33 in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that occurs mainly in synovial joints, causing synovial inflammation and joint injury. If diagnosed and treated in time, the disease can be well controlled. However, in clinical practice, patients often fail to get timely and effective treatment due to misdiagnosis, missed diagnosis, and other reasons, resulting in deterioration of the condition and poor prognosis, seriously affecting the patient's quality of life. So far, the pathogenesis of RA is still unclear. In recent years, it has been found that the imbalance of cytokines plays a vital role in the occurrence and development of RA. Most RA-related cytokines are produced by immune cells, which bind to the specific receptors of effector cells through paracrine and autocrine pathways. The effect of cytokines on inflammation can be divided into pro-inflammatory and anti-inflammatory factors. When the impact of pro-inflammatory factors is more significant than anti-inflammatory factors, the condition of RA will be aggravated, resulting in more inflammatory severe reactions and immune disorders. Interleukin-33 (IL-33) is a new member of the interleukin-1(IL-1) family, and its receptor is suppression of tumorigenicity 2 (ST2). IL-33 plays a vital role in immune diseases such as RA by promoting a series of biochemical reactions in macrophages, mast cells, granulocytes, and other cells. This article aims to summarize the research progress of IL-33 in the pathogenesis of RA in recent years, discuss its role in the pathogenesis of RA, and provide new ideas for the prevention and treatment of RA in the future.

Use of some bone-related cytokines as predictors for rheumatoid arthritis severity by neural network analysis

Background. Rheumatoid arthritis (RA) is characterized by synovial membrane inflammation that results in joint damage. Many earlier studies have measured cytokines for a better diagnosis of RA. In the present study, three bone biomarkers (osteopontin, Stromelysin-1 (MMP3), and vascular endothelial growth factor-A (VEGF)) are examined for their ability to estimate the severity of disease by using artificial neural network (NN) analysis and regression analysis. Methods: The study enrolled 87 RA patients and 44 healthy control subjects. The biomarkers were measured by the enzyme-linked immunosorbent assay (ELISA) technique. Disease Activity Score (28 joints) and C-reactive protein (CRP) (DAS28-CRP) was calculated by using (DAS28-CRP) calculator. The patients with DAS28-CRP5.1 are considered as having high disease activity (HDA). While patients group with DAS28-CRP5.1 are considered as moderate disease activity (MDA). The neural network (NN) analysis was used for the differentiation between groups. Results. Results showed that the most sensitive predictor for high disease activity (HDA) of RA is MMP3, followed by osteopontin and VEGF. These three biomarkers can differentiate significantly between HDA and moderate disease activity (MDA) with a relatively high size effect (Partial 2=0.323, p0.001). HDA group has a significantly higher MMP3, CRP, RF, and anti-citrullinated protein antibodies (ACPA) than the MDA group. Conclusions. The use of the NN analysis indicated that the measured biomarkers help predict the HDA state in RA patients. MMP3 and osteopontin are diagnostic biomarkers for the severity of RA disease and related to many disease-related characteristics with a sensitivity of 88.9% and specificity of 68.4%.

Association Between Sleep Traits and Rheumatoid Arthritis: A Mendelian Randomization Study

Currently, the causal association between sleep disorders and rheumatoid arthritis (RA) has been poorly understood. In this two-sample Mendelian randomization (TSMR) study, we tried to explore whether sleep disorders are causally associated with RA. Seven sleep-related traits were chosen from the published Genome-Wide Association Study (GWAS): short sleep duration, frequent insomnia, any insomnia, sleep duration, getting up, morningness (early-to-bed/up habit), and snoring, 27, 53, 57, 57, 70, 274, and 42 individual single-nucleotide polymorphisms (SNPs) (P < 5 × 10-8) were obtained as instrumental variables (IVs) for these sleep-related traits. Outcome variables were obtained from a public GWAS study that included 14,361 cases and 43,923 European Ancestry controls. The causal relationship between sleep disturbances and RA risk were evaluated by a two-sample Mendelian randomization (MR) analysis using inverse variance weighted (IVW), MR-Egger regression, weighted median, and weight mode methods. MR-Egger Regression and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) were used to test for horizontal pleomorphism and outliers. There was no evidence of a link between RA and frequent insomnia (IVW, odds ratio (OR): 0.99; 95% interval (CI): 0.84-1.16; P = 0.858), any insomnia (IVW, OR: 1.09; 95% CI: 0.85-1.42; P = 0.489), sleep duration (IVW, OR: 0.65, 95% CI: 0.38-1.10, P = 0.269), getting up (IVW, OR: 0.56, 95% CI: 0.13-2.46, P = 0.442), morningness (IVW, OR: 2.59; 95% CI: 0.73-9.16; P = 0.142), or snoring (IVW, OR: 0.95; 95% CI: 0.68-1.33; P = 0.757). Short sleep duration (6h) had a causal effect on RA, as supported by IVW and weighted median (OR: 1.47, 95% CI: 1.12-1.94, P = 0.006; OR: 1.43, 95%CI:1.01-2.05, P = 0.047). Sensitivity analysis showed that the results were stable. Our findings imply that short sleep duration is causally linked to an increased risk of RA. Therefore, sleep length should be considered in disease models, and physicians should advise people to avoid short sleep duration practices to lower the risk of RA.