Pre-treatment interleukin-6 levels strongly affect bone erosion progression and repair detected by magnetic resonance imaging in rheumatoid arthritis patients

Objective. To examine the relationship between MRI structural damage and repair and plasma inflammatory cytokines in patients with RA. Methods. A total of 88 newly diagnosed, untreated RA patients were enrolled. Contrast MRI of the dominant hand and X-rays of the hands and feet were performed at baseline and 1 year later. MR images were evaluated using RA MRI scoring, and X-raywere assessed by the modified total Sharp score. Erosion progression was defined as changes in RA MRI scoring erosion or modified total Sharp score erosion of >0.5. Erosion repair was defined as erosion score changes of less than -0.5. Plasma levels of 10 cytokines were measured by electrochemiluminescence assay. Results. Progression of bone erosion and repair were observed more frequently in MRI than in X-rays (erosion, 52% vs 26%, P < 0.001; repair, 26% vs 15%, P = 0.003, respectively). Baseline IL-6 levels and seropositivity were independent relevant factors for MRI erosion progression, with IL-6 having stronger effect than seropositivity. A receiver operating characteristic curve identified the baseline IL-6 level of 7.6 pg/ml for predicting erosion progression during 1 year, with an area under the curve of 0.82; higher IL-6 levels resulted in more erosion progression. Baseline low IL-6 was also an independent predictor for MRI erosion repair. Conclusion. In newly diagnosed, untreated RA patients, baseline plasma IL-6 levels are responsible for 1-year MRI bone erosion progression and repair.