Dickkopf-1 level is lower in patients with ankylosing spondylitis than in healthy people and is not influenced by anti-tumor necrosis factor therapy

(1) To compare the serum levels of Dickkopf-1 (DKK-1) and bone biomarkers in patients with ankylosing spondylitis (AS) and healthy controls. (2) To examine the effects of anti-tumor necrosis factor-α (TNF-α) therapy for 3 months on bone biomarkers in patients with AS. We measured the levels of DKK-1, osteocalcin, osteoprotegerin, and C-terminal telopeptide of type I collagen (CTX-1) in patients with AS and in healthy controls at baseline and 3 months after initiating anti-TNF-α therapy in AS patients. Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores were also measured before and after anti-TNF-α therapy in AS patients. Serum levels of DKK-1 were significantly lower in the AS patients than in the controls ( P