Clinical Diagnostic Value of Dkk-1 Level in Ankylosing Spondylitis: Comparison of Test Systems Based on Aptamers and Antibodies.

In ankylosing spondylitis, the pathological metabolism of the bone tissue is regulated by various proteins; of these, Dkk-1 protein, an antagonist of the Wnt-signaling pathway, is of particular interest. We compared the methods of Dkk-1 detection in the blood serum of patients with ankylosing spondylitis (conventional ELISA and aptamer/antibody assay) and analyzed the relationship between Dkk-1 level and structural progression of ankylosing spondylitis and secondary osteoporosis. Dkk-1 levels in patients were significantly increased and depended on the stage of the disease, but not on the presence/absence of osteoporosis. Thus, Dkk-1 is a potential serum marker of progression of ankylosing spondylitis reflecting a tendency to structural progression of the disease before the appearance of radiographic changes. The results obtained by both methods practically coincided, which suggests good prospects for applying DNA aptamer-based test system.