CXCL13 predicts long term radiographic status in early rheumatoid arthritis.

Objectives It remains challenging to identify rheumatoid arthritis (RA) patients at a high risk of joint destruction. The C-X-C motif chemokine 13 (CXCL13) has previously been suggested as a marker of disease activity in RA. Here, we investigate the potential of plasma CXCL13 as a marker of long-term radiographic status and progression. Methods CXCL13 was measured in plasma from treatment naive RA patients (n = 158) with 11-year follow-up. At baseline, clinical and biochemical disease activity scores were obtained; among these C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), disease activity score in 28 joints with CRP(DAS28CRP), number of, swollen joints (SJC28) and radiographic status, evaluated by total Sharp score (TSS). Age and gender matched healthy controls (HC) were included. Results CXCL13 was significantly increased at baseline and decreased during treatment, however without reaching the level in HC. At baseline, CXCL13 was associated with both CRP and ESR, but not with other markers of disese activity. Baseline CXCL13 correlated with both TSS and radiographic progression (ΔTSS) at 11 years. With a 89% probability, levels of CXCL13 above 85 pg/ml predicted the risk of a TSS of 5 or above, after 11 years of treatment. Comparing with CRP, DAS28CRP, SJC28 and anti-citrullinated peptide antibody status, CXCL13 was superior in predicting 11-year joint destruction. Conclusion In early RA, one single measurement of plasma CXCL13 at baseline, is superior to currently used clinical and serological disease markers, to predict longterm radiographic status and progression.