B-186 14-3-3eta as a Biomarker for Disease Severity and Prognosis in Rheumatoid Arthritis: A Longitudinal Single-Centre Cohort Study

Abstract

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by inflammatory arthritis. While rheumatoid factor (RF) and/or anti–cyclic citrullinated peptide (anti-CCP) antibodies help identify RA patients, 20–30% are seronegative for these two markers creating diagnostic and prognostic challenges. The biomarker 14-3-3eta has been associated with RA disease activity, severity, and treatment response, but U.S.-based data are limited. This study aimed to evaluate serum 14-3-3eta levels in RA compared with disease and healthy controls, assess its association with disease severity, and investigate longitudinal changes in relation to treatment response. Residual serum samples from 111 RA patients at different stages of treatment collected at two time points (mean=18 months apart), 50 spondyloarthritis disease controls, and 50 healthy individuals were analyzed for 14-3-3eta using ELISA (Augurex Life Sciences, Vancouver, Canada). A cut-off of 0.19 ng/mL defined positivity according to manufacturer’s instructions. Disease activity was measured by DAS28-CRP (>2.6 = active; =2.6 = remission). Between-group comparisons were performed using Welch’s t-test of log-transformed values. Positive likelihood ratios (LR+) with 95% confidence intervals were calculated at multiple cut-offs to assess associations with disease severity. Longitudinal changes were analyzed using repeated-measures methods. All analyses were performed using GraphPad Prism and Analyse-it® software. Serum 14-3-3eta levels were higher in patients with RA (geometric mean: 0.125 ng/ml) compared with disease controls (geometric mean: 0.034 ng/ml) and healthy controls (geometric mean: 0.029 ng/ml) (p<0.0001). Using a cutoff of 0.19?ng/mL, 39% of RA patients tested positive for 14-3-3eta, a significantly higher proportion than in disease controls (10%, p<0.001) or healthy individuals (6%, p<0.001). Levels were higher in patients with active disease (geometric mean=0.243) compared with those in remission (geometric mean=0.087) (p<0.01). At initial assessment, the LR+ increased with higher cut-offs: 3.21 (95% CI: 1.24–8.29) at 0.19 ng/mL, 3.36 (95% CI: 1.08–10.49) at 0.45 ng/mL, and 4.13 (95% CI: 1.00–17.07) at 1.1 ng/mL. Longitudinally, declining 14-3-3eta levels corresponded with reduced LR+ at follow-up: 1.17 (95% CI: 0.63–2.17) at 0.19 ng/mL, 0.96 (95% CI: 0.47–1.96) at 0.45 ng/mL, and 1.20 (95% CI: 0.46–3.12) at 1.1 ng/mL. Elevated 14-3-3eta levels distinguished RA patients from disease and healthy controls, supporting specificity. Levels were higher in patients with active disease, suggesting an association with disease severity. Longitudinal declines in 14-3-3eta levels mirrored reductions in disease activity, indicating a possible association with treatment response. Data from this cohort supports 14-3-3eta as a dynamic, RA-specific biomarker with potential utility for assessing disease severity and monitoring therapeutic response.