Association of CXCL13 Serum Level and Ultrasonographic Findings of Joints in Patients with Systemic Lupus Erythematosus and Jaccoud's Arthropathy

Objectives The objective of this paper is to perform an ultrasonography (US) analysis of hands and wrists in two groups of patients with systemic lupus erythematosus (SLE), with and without Jaccoud's arthropathy, matched by age and disease duration and to correlate them with levels of CXCL13 clinical features, laboratory tests and disease activity score. Methods Sixty-four patients with SLE were enrolled, 32 with and 32 without Jaccoud's arthropathy. Each patient underwent physical examination, laboratory tests (including CXCL13 by ELISA) and bilateral US. Synovial hypertrophy, tenosynovitis and erosions were evaluated according to a semiquantitative grading system with a 0-3 rating. US findings were correlated with serum levels of CXCL13, other serological parameters and disease activity index. Results Synovitis was found in 25/64 patients (39%) and tenosynovitis in 14/64 (22%). These findings were more frequent in SLE patients with Jaccoud's arthropathy, particularly tenosynovitis ( p = 0.002) and synovitis ( p = 0.01). Median serum level of CXCL13 was 20.16 pg/ml in the whole population (23.21 pg/ml in the Jaccoud's arthropathy group and 11.48 pg/ml in the group without). There was an association between the presence of disease activity and high level of CXCL13 ( p = 0.004). However, no association was found between high levels of CXCL13 and "arthritis" in SLEDAI, swollen joints on physical examination or synovitis on US. Conclusions US findings in joints of SLE patients with Jaccoud's arthropathy confirm that synovitis and tenosynovitis are common in these patients. In addition, serum level of CXCL13 is associated with disease activity in SLE but does not seem to be a biomarker for arthritis in these patients.