New bone formation in ankylosing spondylitis may be related to low Dickkopf-1 level and three months of anti-TNF-a therapy could not improve serum Dickkopf-1 level.

초록

Background: Recent clinical studies showed that TNF-α blockers could not inhibit radiologic progression in AS after up to 2 years of use. Prior data in patients with ankylosing spondylitis (AS) reported that serum Dickkopf-1 (DKK-1) level was low in patients with AS than in healthy controls suggesting that this might account for the propensity to new bone formation in AS. Objectives: We therefore evaluate serum DKK-1 levels and other bone biomarkers to compare DKK-1 levels in patients with AS and in controls, and to examine the effects of anti-tumor necrosis factor-α (TNF-α) therapy for 3 months on serum DKK-1 levels and other bone biomarkers in AS. Methods: We enrolled 56 patients with AS (47 males/9 females, age 35.1±9.6 years, disease duration 6.9±4.8 years, mean ± SD), and 40 controls (31 male/9 females, age 43.5±8.6 years). We measured the serum levels of DKK-1, osteocalcin, osteoprotegerin, and C-terminal telopeptide of type I collagen (CTX-1) in patients with AS and healthy controls at baseline and three months after initiating anti-TNF-α therapy in AS patients. Results: Serum level of DKK-1 were lower in AS than in controls. Serum osteocalcin, osteoprotegerin levels were significantly higher in AS than in controls. Serum DKK-1 and CTX-1 levels did not change after the three-month anti-TNF-α therapy. Osteocalcin level increased, osteoprotegerin level and BASDAI scores decreased significantly after the three-month anti-TNF-α therapy. Conclusion: Serum DKK-1 level was lower in patients with AS than in healthy controls and did not recover after three months of anti-TNF-α therapy in the AS patients despite the marked improvement in BASDAI scores.