Objective: To determine the serum levels of soluble osteoprotegerin (OPG), decoy receptor of receptor activator of nuclear factor kB ligand (RANKL), in patients with systemic lupus erythematosus (SLE) and to assess the its relationships with certain clinical manifestations. Methods: Serum levels of OPG in 60 patients with SLE and 30 healthy controls were determined by enzyme-linked immunosorbent assay. At the time of serum sampling, clinical manifestations and lupus disease activity index (SLEDAI) were assessed. Results: Serum levels of OPG in 60 patients with SLE were significantly higher than in 30 healthy controls (1,058⁑699 versus 806⁑113 pg/mL, p=0.008). Patients with active disease had higher levels of OPG levels than those with inactive disease (1,355⁑837 versus 760⁑113 pg/mL, p＜0.001). Serum OPG levels correlated with SLEDAI (γ=0.588, p＜0.0001), anti-dsDNA antibody titers (γ=0.337, p=0.009) and serum MCP-1 levels (γ=0.485, p＜0.0001). In particular, serum OPG levels were found to be significantly increased in patients with neurological manifestation compared to those without (1,504⁑1,152 versus 918⁑376 pg/mL, p=0.004). Conclusion: The results of this study suggest that serum OPG levels are increased in patients with SLE. Serum OPG has a role as marker for disease activity and its increased levels reflect the involvement of neurological manifestation.

Keywords: Systemic lupus erythematosus, Osteoprotegerin, MCP-1, SLEDAI