Evaluation of various biomarkers related with syndesmophytes in patients with ankylosing spondylitis

Objective: We aimed to determine the level of different biomarkers and analyze their relationship with syndesmophytes in ankylosing spondylitis (AS) patients Methods: We included 94 AS patients (49 non-syndesmophyte, 67.3% male [M], 40.7±8.7 years; 45 with syndesmophyte, 71.1% M, 43.9±9.9 years) and 68 healthy controls (44.2±10.6 years and 70.6% M) in the study group. Lateral plain radiographs of the cervical and lumbar spine were used for scoring syndesmophytes. Any presence of syndesmophytes or bridging syndesmophytes was categorized as positive. Fetuin-A, dickkopf-1 (DKK-1), sclerostin, interleukin-6 (IL-6), high sensitive C-reactive protein (hs-CRP) and bone morphogenetic protein-7 (BMP-7) were studied. Results: AS patients with syndesmophytes had significantly higher levels of fetuin-A compared to the patients without syndesmophytes and healthy controls. On the other hand fetuin-A was not different between syndesmophyte negative patients and controls. DKK-1 and BMP-7 levels were significantly different in AS patients (both with and without syndesmophytes) from healthy controls. However, sclerostin concentrations were similar between the groups. In regression analysis fetuin-A and Bath Ankylosing Spondylitis Metrology Index were significantly predicting syndesmophytes. Receiver operating characteristic curve revealed that fetuin-A concentrations greater than 1.11 mg/mL had a good sensitivity and specificity for discriminating syndesmophyte positive and negative AS patients. Conclusion: Among the biomarkers we studied, fetuin-A may be of interest for prediction of syndesmophytes in AS. Key words: Ankylosing spondylitis; Bone formation; Fetuin-A; Dickkopf-1 protein, human; Sclerostin protein, human; Bone morphogenetic protein 7;