LEVELS OF IL-6 AND OTHER INFLAMMATORY PROTEINS IN EARLY RA PREDICT JOINT DAMAGE PROGRESSION OVER 5 YEARS

Background Joint damage in rheumatoid arthritis (RA) remains a significant problem. Identification of biomarkers associated with joint destruction can improve our understanding of underlying disease processes and future management.

Objectives To evaluate inflammatory proteins as potential predictors of radiographic progression of joint damage.

Methods Consecutive early RA patients (symptom duration 0.50 were investigated as potential predictors of radiographic progression. Logistic and linear regression models were used to assess associations with rapid radiographic progression (RRP; ≥5 SHS/year) and progression of SHS over 5 years.

Results Data on baseline levels of proteins, and radiographs at baseline and 5 years were available for 114 patients. The median progression of SHS was 11 (interquartile 2-19). For potential biomarkers with an a priori hypothesis, IL-6 significantly predicted both RRP and progression of SHS over 5 years analyzed as a continuous variable [adjusted ß = 0.09 per SD, p=0.032, adjusted for rheumatoid factor (RF) and baseline SHS]. A significant positive association for matrix metalloproteinase 1 (MMP-1) was observed in the unadjusted analysis for SHS progression, but not for RRP (Table 1). In the exploratory analyses, S100 calcium-binding protein A12 (EN-RAGE) was positively, and TNF-related apoptosis-inducing ligand (TRAIL) negatively associated with both outcomes.

Conclusion Plasma levels of IL-6 at RA diagnosis predict degree of future joint damage. EN-RAGE and TRAIL, both modulators of NF-κB which is known to regulate immune response, are potential biomarkers that need further investigation.