Patients with seronegative rheumatoid arthritis have a different phenotype than seropositive patients: A clinical and ultrasound study

Utility of polygenic risk scores to aid in the diagnosis of rheumatic diseases

Rheumatic diseases (RDs) are characterized by autoimmunity and autoinflammation and are recognized as complex due to the interplay of multiple genetic, environmental, and lifestyle factors in their pathogenesis. The rapid advancement of genome-wide association studies (GWASs) has enabled the identification of numerous single nucleotide polymorphisms (SNPs) associated with RD susceptibility. Based on these SNPs, polygenic risk scores (PRSs) have emerged as promising tools for quantifying genetic risk in this disease group. This chapter reviews the current status of PRSs in assessing the risk of RDs and discusses their potential to improve the accuracy of the diagnosis of these complex diseases through their ability to discriminate among different RDs. PRSs demonstrate a high discriminatory capacity for various RDs and show potential clinical utility. As GWASs continue to evolve, PRSs are expected to enable more precise risk stratification by integrating genetic, environmental, and lifestyle factors, thereby refining individual risk predictions and advancing disease management strategies.

Differences in referral path, clinical and radiographic outcomes between seronegative and seropositive rheumatoid arthritis Mexican Mestizo patients: A cohort study

BACKGROUND

The study compared the referral path, the first two-year clinical outcomes, and the first five-year radiographic outcomes between seronegative patients (SNPs) from a recent-onset rheumatoid arthritis dynamic cohort initiated in 2004 and seropositive patients (SPPs). Predictors of incidental erosive disease were investigated.

PATIENTS AND METHODS

Up to March 2023, one independent observer reviewed the charts from 188 patients with at least two years of clinical assessments and up to five years of annual radiographic assessments. SNPs were defined when baseline RF and ACPA serum titers were within local normal ranges. The erosive disease was defined on hand and/or foot radiographs when at least one unequivocal cortical bone defect was detected. The incidental erosive disease was defined in baseline erosive disease-free patients who developed erosions at follow-ups. Multivariate Cox regression analyses identified hazard ratios (95% confidence interval) for factors to predict incidental erosive disease.

RESULTS

There were 17 (9%) SNPs, and they had a shorter time from symptoms onset to first physician evaluation, visited a lower number of physicians, and received less intensive treatment at referral and during the first years of follow-up than SPPs. Also, they had fewer 0-66 swollen joints and were less frequently persistent on therapy. The erosive disease was detected only in SPPs, and its frequency increased from 10.1% at baseline to 36.1% at the five-year radiographic assessment. There were 53 (31.4%) patients with incidental erosive disease, and differences between SPPs and SNPs were statistically significant at the feet location. Incidental erosive disease was predicted by baseline ACPA, ESR, substantial morning stiffness, and cumulative CRP.

CONCLUSIONS

SNPs showed mild differences in their referral path and clinical outcomes compared to SPPs. However, erosive disease was detected only in SPPs and was predicted by baseline and cumulative clinical and serologic variables.

Clinical Phenotypes, Serological Biomarkers, and Synovial Features Defining Seropositive and Seronegative Rheumatoid Arthritis: A Literature Review

Rheumatoid arthritis (RA) is a chronic autoimmune disorder which can lead to long-term joint damage and significantly reduced quality of life if not promptly diagnosed and adequately treated. Despite significant advances in treatment, about 40% of patients with RA do not respond to individual pharmacological agents and up to 20% do not respond to any of the available medications. To address this large unmet clinical need, several recent studies have focussed on an in-depth histological and molecular characterisation of the synovial tissue to drive the application of precision medicine to RA. Currently, RA patients are clinically divided into "seropositive" or "seronegative" RA, depending on the presence of routinely checked antibodies. Recent work has suggested that over the last two decades, long-term outcomes have improved significantly in seropositive RA but not in seronegative RA. Here, we present up-to-date differences in epidemiology, clinical features, and serological biomarkers in seronegative versus seropositive RA and discuss how histological and molecular synovial signatures, revealed by recent large synovial biopsy-based clinical trials, may be exploited to refine the classification of RA patients, especially in the seronegative group.

Clinical implications of seropositive and seronegative autoantibody status in rheumatoid arthritis patients: A comparative multicentre observational study

Background and Objectives

Rheumatoid factor (RF) and anti-cyclic citrullinated protein (anti-CCP) have been used to improve the diagnosis and prognosis of rheumatoid arthritis (RA). However, their association with RA disease phenotypes, individually and in combination, is not well studied. The aim of the study was to compare patients' and disease characteristics, activity and severity in double seronegative (DNRA), single seropositive RF, single seropositive anti-CCP and double seropositive (DPRA) patients.

Methods

Adults subjects with RA from Egyptian College of Rheumatology (ECR) database who had RF and anti-CCP results available were included. Demographic, clinical features, disease activity score 28 (DAS28), Health Assessment Questionnaire (HAQ) and laboratory data were collected and compared among different RA groups.

Results

5268 RA patients with mean age of 44.9±11.6 years, and 4477 (85%) were females. 2900 (55%) had DPRA, 892 (16.9%) had single positive RF, 597 (11.3%) had single positive anti-CCP while 879 (16.7%) had DNRA. Patients with DPRA had significantly high percentage of metabolic syndrome (19.3%, P < 0.001), and functional impairment using HAQ (P = 0.01). Older age (RRR [relative risk ratio]: 1.03, 95%CI: 1.0, 1.0, P = 0.029), greater DAS28 (RRR: 1.51, 95%CI: 1.2, 1.9, P < 0.001), higher steroid use (RRR: 2.4, 95%CI: 1.36, 4.25, P = 0.002) were at higher risk of DPRA while longer disease duration (RRR: 1.08, 95%CI: 1.01, 1.16, P = 0.017) and fibromyalgia syndrome (RRR: 2.54, 95%CI: 1.10, 5.88, P = 0.028) were associated with higher odds of single positive RF status.

Conclusion

Dual antibody-positive status has higher disease activity and severity, and higher chance of development of metabolic syndrome; highlighting the implicated role of inflammation, atherogenesis and cardiovascular disease risk in RA.

Investigation of periodontitis, halitosis, xerostomia, and serological characteristics of patients with osteoarthritis and rheumatoid arthritis and identification of new biomarkers

Rheumatoid arthritis (RA) and osteoarthritis (OA) are two different types of arthritis. Within RA, the subsets between seronegative RA (snRA) and seropositive RA (spRA) represent distinct disease entities; however, identifying clear distinguishing markers between them remains a challenge. This study investigated and compared the oral health conditions in patients with RA and OA to clarify the differences from healthy controls. In addition, we investigated the serological characteristics of the patients, the factors that distinguished patients with RA from those with OA, and the main factors that differentiated between snRA and spRA patients. A total of 161 participants (mean age: 52.52 ± 14.57 years, 32 males and 129 females) were enrolled in this study and categorized as: normal (n = 33), OA (n = 31), and RA (n = 97). Patients with RA were divided into the following two subtypes: snRA (n = 18) and spRA (n = 79). Demographics, oral health, and serological characteristics of these patients were compared. The prevalence of periodontal diseases was significantly higher in patients with OA (100%) and RA (92.8%) than in healthy controls (0.0%). However, the presence of periodontal diseases was not utilized as a distinguishing factor between OA and RA. Xerostomia occurred more frequently in patients with RA (84.5%) than in patients with OA (3.2%) and healthy controls (0.0%) (all p < 0.001). ROC analysis revealed that periodontal disease was a very strong predictor in the diagnosis of OA compared to healthy controls, with an AUC value of 1.00 (p < 0.001). Additionally, halitosis (AUC = 0.746, 95% CI 0.621-0.871, p < 0.001) and female sex (AUC = 0.663, 95% CI 0.529-0.797, p < 0.05) were also significant predictors of OA. The strongest predictors of RA diagnosis compared to healthy controls were periodontal diseases (AUC = 0.964), followed by xerostomia (AUC = 0.923), age (AUC = 0.923), female sex (AUC = 0.660), and halitosis (AUC = 0.615) (all p < 0.05). Significant serological predictors of RA were anti-CCP Ab (AUC = 0.808), and RF (AUC = 0.746) (all p < 0.05). In multiple logistic regression analysis, xerostomia (odds ratio, OR: 8124.88, 95% CI 10.37-6368261.97, p-value = 0.008) and Anti-CCP Ab (OR: 671.33, 95% CI 2.18-207,074.02, p = 0.026) were significant predictors for RA compared to OA. When diagnosing spRA compared to snRA, anti-CCP Ab (AUC = 1.000, p < 0.001) and RF (AUC = 0.910, 95%CI 0.854-0.967, p < 0.001) had outstanding predictive performances. Therefore, clinicians and researchers should thoroughly evaluate the oral status of both OA and RA patients, alongside serological factors, and consider these elements as potential predictors.

Influence of anti-carbamylated protein antibodies on disease activity and joint erosions in seronegative and seropositive rheumatoid arthritis

Anti-carbamylated protein (anti-CarP) antibodies are promising biomarkers in rheumatoid arthritis (RA), although their significance in seronegative disease (SNRA) remains uncertain. To assess the influence of anti-CarP antibodies on disease activity and erosive joint damage in SNRA patients. In RA patients, rheumatoid factor (RF), anti-citrullinated protein antibodies, and anti-CarP antibodies were measured. Disease activity was assessed using DAS28-CRP and SDAI indices, while musculoskeletal ultrasound identified bone erosions. A total of 77 patients were enrolled, comprising 49 with seropositive RA (SPRA) and 28 with SNRA. Notably, 28% of SPRA and 10% of SNRA patients were positive to anti-CarP antibodies. Anti-CarP-positive patients exhibited elevated C-reactive protein (median 10.6, interquartile range 4.6-20.0 vs. 3.4, 1.7-9.9 mg/L; p = 0.005), erythrocyte sedimentation rate (34, 19-46 vs. 16, 7-25 mm/h; p = 0.002), DAS28-CRP (3.2, 2.6-4.2 vs. 2.6, 1.9-3.5; p = 0.048), and SDAI (19.9, 6.3-32.1 vs. 10.9, 5.5-18.1; p = 0.034) indices. Multivariate analysis revealed RF positivity as the sole predictor for anti-CarP antibodies (odds ratio [OR] = 5.9). Musculoskeletal ultrasound revealed bone erosions in 36% of RA patients; 35% among anti-CarP-negative patients and 40% among anti-CarP-positive patients. Notably, RF presence (OR = 44.3) and DAS28-CRP index (OR = 2.4) emerged as predictors of musculoskeletal ultrasound-confirmed erosive joint disease. Anti-CarP antibodies are detected at similar frequencies among both SPRA and SNRA patients. While associated with increased disease activity, these antibodies did not correlate with increased erosive joint damage.

When Autoantibodies Are Missing: The Challenge of Seronegative Rheumatoid Arthritis

Seronegative rheumatoid arthritis (SNRA) is characterized by the absence of both rheumatoid factor (RF) and antibodies against the cyclic citrullinated protein (ACPA) in serum. However, the differences between the two forms of RA are more complex and have not yet been definitively characterized. Several lines of evidences support the idea that there are specific elements of the two forms, including genetic background, epidemiology, pathogenesis, severity of progression over time, and response to therapy. Clinical features that may differentiate SNRA from SPRA are also suggested by data obtained from classical radiology and newer imaging techniques. Although new evidence seems to provide additional help in differentiating the two forms of RA, their distinguishing features remain largely elusive. It should also be emphasized that the distinctive features of RA forms, if not properly recognized, can lead to the underdiagnosis of SNRA, potentially missing the period called the "window of opportunity" that is critical for early diagnosis, timely treatment, and better prognosis. This review aims to summarize the data provided in the scientific literature with the goal of helping clinicians diagnose SNRA as accurately as possible, with emphasis on the most recent findings available.

The Role of Autophagy as a Trigger of Post-Translational Modifications of Proteins and Extracellular Vesicles in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease, characterized by persistent joint inflammation, leading to cartilage and bone destruction. Autoantibody production is directed to post-translational modified (PTM) proteins, i.e., citrullinated or carbamylated. Autophagy may be the common feature in several types of stress (smoking, joint injury, and infections) and may be involved in post-translational modifications (PTMs) in proteins and the generation of citrullinated and carbamylated peptides recognized by the immune system in RA patients, with a consequent breakage of tolerance. Interestingly, autophagy actively provides information to neighboring cells via a process called secretory autophagy. Secretory autophagy combines the autophagy machinery with the secretion of cellular content via extracellular vesicles (EVs). A role for exosomes in RA pathogenesis has been recently demonstrated. Exosomes are involved in intercellular communications, and upregulated proteins and RNAs may contribute to the development of inflammatory arthritis and the progression of RA. In RA, most of the exosomes are produced by leukocytes and synoviocytes, which are loaded with PTM proteins, mainly citrullinated proteins, inflammatory molecules, and enzymes that are implicated in RA pathogenesis. Microvesicles derived from cell plasma membrane may also be loaded with PTM proteins, playing a role in the immunopathogenesis of RA. An analysis of changes in EV profiles, including PTM proteins, could be a useful tool for the prevention of inflammation in RA patients and help in the discovery of personalized medicine.

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

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

Autoantibodies against complement factor B in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disorder affecting the joints. Many patients carry anti-citrullinated protein autoantibodies (ACPA). Overactivation of the complement system seems to be part of the pathogenesis of RA, and autoantibodies against the pathway initiators C1q and MBL, and the regulator of the complement alternative pathway, factor H (FH), were previously reported. Our aim was to analyze the presence and role of autoantibodies against complement proteins in a Hungarian RA cohort. To this end, serum samples of 97 ACPA-positive RA patients and 117 healthy controls were analyzed for autoantibodies against FH, factor B (FB), C3b, C3-convertase (C3bBbP), C1q, MBL and factor I. In this cohort, we did not detect any patient with FH autoantibodies but detected C1q autoantibodies in four patients, MBL autoantibodies in two patients and FB autoantibodies in five patients. Since the latter autoantibodies were previously reported in patients with kidney diseases but not in RA, we set out to further characterize such FB autoantibodies. The isotypes of the analyzed autoantibodies were IgG2, IgG3, IgGκ, IgGλ and their binding site was localized in the Bb part of FB. We detected in vivo formed FB-autoanti-FB complexes by Western blot. The effect of the autoantibodies on the formation, activity and FH-mediated decay of the C3 convertase in solid phase convertase assays was determined. In order to investigate the effect of the autoantibodies on complement functions, hemolysis assays and fluid phase complement activation assays were performed. The autoantibodies partially inhibited the complement-mediated hemolysis of rabbit red blood cells, inhibited the activity of the solid phase C3-convertase and C3 and C5b-9 deposition on complement activating surfaces. In summary, in ACPA-positive RA patients we identified FB autoantibodies. The characterized FB autoantibodies did not enhance complement activation, rather, they had inhibitory effect on complement. These results support the involvement of the complement system in the pathomechanism of RA and raise the possibility that protective autoantibodies may be generated in some patients against the alternative pathway C3 convertase. However, further analyses are needed to assess the exact role of such autoantibodies.