Anticyclic Citrullinated Peptide Antibodies 3.1 and Anti-CCP-IgA Are Associated with Increasing Age in Individuals Without Rheumatoid Arthritis

Salivary anti-cyclic citrullinated peptide as a screening tool for rheumatoid arthritis

Objectives: This study aims to evaluate the sensitivity and specificity of salivary anti-cyclic citrullinated peptide 3 (anti-CCP3) for the early diagnosis of rheumatoid arthritis.

Patients and methods: Between June 2017 and April 2019, a total of 63 patients with rheumatoid arthritis (10 males, 53 females; mean age: 50.4±9.5 years; range, 27 to 74 years) and 49 healthy controls (8 males, 41 females; mean age: 49.3±9.3 years; range 27 to 67 years) were included. Salivary samples were collected by passive drooling. Anti-cyclic citrullinated peptide analyses of salivary and serum samples were performed.

Results: The mean polyclonal immunoglobulin (Ig)G-IgA anti-CCP3 salivary levels were significantly different in patients (149.2±134.2) compared to healthy controls (28.5±23.9). The mean polyclonal IgG-IgA anti-CCP3 serum levels were measured as 254.0±169.5 in patients and 3.8±3.6 in healthy individuals. The diagnostic accuracy analysis of salivary IgG-IgA anti-CCP3 results in an area under the curve (AUC) of 0.818, as well as 91.84% specificity and 61.90% sensitivity.

Conclusion: Salivary anti-CCP3 may be considered as an additional screening test for rheumatoid arthritis.

Low levels of anti-cyclic citrullinated peptide (CCP) 3.1 associated with diseases other than rheumatoid arthritis

Our aim was to investigate the newest generation anti-cyclic citrullinated peptide (CCP) antibody 3.1 assay in diagnosing rheumatoid arthritis (RA) compared with other autoimmune and non-autoimmune diseases. We performed a retrospective observational chart review of patients with a positive CCP level over a one-year period at a single academic institution and assessed the associated diagnoses after at least six-months of follow-up. Of the 281 CCP positive patients during that period, 48% had a diagnosis of RA. The positive predictive value of RA in patients with a high CCP 3.1 assay was 0.619 compared to 0.248 with a low positive CCP 3.1 assay (P < .0001). Overall, there was a lower than expected positive predictive value of CCP 3.1 level with an RA diagnosis, though the likelihood of having an RA diagnosis was higher with a higher CCP level.

A pilot study of a machine-learning tool to assist in the diagnosis of hand arthritis

OBJECTIVE

Arthritis is a common condition, which frequently involves the hands. Patients with inflammatory arthritis have been shown to experience significant delays in diagnosis. We sought to develop and test a screening tool combining an image of a patient's hands, a short series of questions, and a single examination technique, to determine the most likely diagnosis in a patient presenting with hand arthritis. Machine learning techniques were used to develop separate algorithms for each component, which were combined to produce a diagnosis.

METHODS

280 consecutive new patients presenting to a Rheumatology practice with hand arthritis were enrolled. Each patient completed a 9-part questionnaire, had photographs taken of each hand, and had a single examination result recorded. The Rheumatologist diagnosis was recorded following a 45-minute consultation. The photograph algorithm was developed from 1000 previous hand images, and machine learning techniques were applied to the questionnaire results, training several models against the diagnosis from the Rheumatologist.

RESULTS

The combined algorithms in this study were able to predict inflammatory arthritis with an accuracy, precision, recall and specificity of 96·8%, 97·2%, 98·6% and 90·5% respectively. Similar results were found when inflammatory arthritis was subclassified into rheumatoid arthritis and psoriatic arthritis. The corresponding figures for osteoarthritis were 79·6%, 85·9%, 61·9% and 92·6%.

CONCLUSION

This study demonstrates a novel application combining image-processing and a patient questionnaire with applied machine-learning methods, to facilitate the diagnosis of patients presenting with hand arthritis. Preliminary results are encouraging for the application of such techniques in clinical practice. This article is protected by copyright. All rights reserved.

Presence of salivary IgA anti-citrullinated protein antibodies associate with higher disease activity in patients with rheumatoid arthritis

Background

Circulating IgA anti-citrullinated protein antibodies (ACPA) associate with more active disease, but a previous study implied that salivary IgA ACPA is related to a less severe disease. Therefore, we aimed to characterize the IgA ACPA response in the saliva and serum in relation to clinical picture and risk factors among patients with rheumatoid arthritis (RA).

Methods

RA patients (n = 196) and healthy blood donors (n = 101), included in the cross-sectional study “Secretory ACPA in Rheumatoid Arthritis” (SARA), were analyzed for ACPA of IgA isotype, and for subclasses IgA1 and IgA2 ACPA in paired saliva and serum samples using modified enzyme-linked immunosorbent assays (ELISA) targeting reactivity to a cyclic citrullinated peptide (anti-CCP). Cutoff levels for positive tests were set at the 99th percentile for blood donors. Antibody levels were related to clinical characteristics, radiographic damage, smoking habits, and carriage of HLA-DRB1/shared epitope (SE).

Results

IgA ACPA in the saliva was found in 12% of RA patients, IgA1 occurred in 10%, and IgA2 in 9%. In serum, IgA ACPA was found in 45% of the patients, IgA1 in 44%, and IgA2 in 39%. Levels of IgA ACPA in the saliva correlated significantly with serum levels of IgA (r = 0.455). The presence of salivary IgA ACPA was associated with a higher erythrocyte sedimentation rate (ESR), 28-joint disease activity score, tender joint count, and patient global assessment at the time of sampling. None of the antibodies was associated with smoking, SE, or radiographic damage.

Conclusion

Salivary IgA ACPAs were detected in a subset of RA patients in association with higher disease activity. This suggests that mucosal ACPA responses in the oral cavity may contribute to disease-promoting processes in RA.

Heightened Levels of Antimicrobial Response Factors in Patients With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic progressive autoimmune disease leading to considerable disability over time. The disease can be characterized by the presence of multiple autoantibodies in the serum and synovial fluid. Microbial dysbiosis is proposed to play a role in the pathogenesis of RA. Increased systemic bacterial exposure leads to elevated levels of antimicrobial response factors (ARFs) in the circulation. In the present study, we tested whether RA patients have increased levels of ARFs by analyzing the levels of multiple ARFs in serum from RA patients and healthy age and sex-matched controls. The levels of soluble CD14 (sCD14), lysozyme, and CXCL16 were significantly elevated in RA patients compared to healthy controls. Lipopolysaccharide binding protein (LBP) levels remained unchanged in RA patients compared to healthy controls. A positive correlation of LBP with rheumatoid factor (RF) was also found in RA subjects. Interestingly, the levels of anti-endotoxin core antibodies (EndoCAb) IgM, total IgM, EndoCAb IgA, and total IgA were significantly elevated in RA patients compared to healthy controls. No significant changes in the levels of EndoCAb IgG and total IgG were observed in RA patients compared to healthy controls. Furthermore, lysozyme and CXCL16 levels were positively correlated with disease severity among RA subjects. Increases in the levels of several ARFs and their correlations with clinical indices suggest systemic microbial exposure in the RA cohort. Modulation of microbial exposure may play an important role in disease pathogenesis in individuals with RA.