Interleukin-6 promotes arthritis and joint deformation in patients with systemic lupus erythematosus

The underlying mechanisms for the subsets of self-limiting, intermittent or chronic and deforming arthritis in systemic lupus erythematosus (SLE) are not well understood. We performed a cross-sectional analysis of pro-inflammatory cytokines (IL-1β, IL-2, IL-6, IL-8 and TNF-α) and joint status in 47 SLE patients (79% females, age 42 years, disease duration 8.6 years). All cytokines levels were significantly elevated in SLE patients compared with controls, but only IL-2 and IL-8 levels were higher than in patients with rheumatoid arthritis. SLE patients with ongoing synovitis (19%) and joint deformities (11%) had increased erythrocyte sedimentation rate (ESR), IL-6 and anti-dsDNA Ab levels. IL-6 levels correlated with ESR, anti-dsDNA Ab and haemoglobin, but not with C-reactive protein levels. Arthritis constitutes a considerable burden of disease in SLE over time, and joint deformations are associated with longstanding disease and arthritis flare rates. IL-6 is a potential biomarker and therapeutic target in the prevention of joint damage in SLE arthritis.