The serum levels of inhibitors of wingless/beta-catenin in patients with ankylosing spondylitis and rheumatoid arthritis and the relationship with anti-TNF treatments

Objective: The primary aim of the study was to compare the serum levels of Dickkopf-1 (Dkk-1) and sclerostin in patients with ankylosing spondylitis (AS), rheumatoid arthritis (RA) and healthy controls. The secondary aim was to evaluate the effects of anti-tumor necrosis factor- (anti-TNF-) treatments on levels of Dkk-1 and sclerostin. The last aim was to evaluate any relationship between Dkk-1/Sclerostin and Ankylosing Spondylitis Disease Activity Score (ASDAS). Methods: We included 70 AS patients (35 anti-TNF- treated, 35 anti-TNF- naive), 60 RA patients (30 anti-TNF- treated, 30 anti-TNF- naive) and 31 healthy controls in the study group. Serum dkk-1, sclerostin, C-reactive protein, erythrocyte sedimentation rate were assessed in patients and healthy controls. Ankylosing Spondylitis Disease Activity Score (ASDAS), Bath Ankylosing Spondylitis Disease Activity Score (BASDAI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Functional Index (BASFI), Disease Activity Score-28 (DAS-28), Health Assessment Questionnare (HAQ), Short Form-36 (SF-36) were calculated in patients. Radiographs were scored according to modified Stoke AS Spine Score (mSASSS) and Sharp/van der Heijde method by an experienced radiologist who was blind to the patients identity. Results: AS patients-treated with anti-TNF- had higher scores of BASMI and mSASSS compared to the AS patients-anti-TNF- naive. Serum levels of dkk-1 and sclerostin were significantly lower in patients with AS and RA than in healthy controls. There was an inversely correlation between dkk-1 levels with ASDAS and BASMI in patients with AS. There was no correlation between dkk-1 or sclerostin levels with mSASSS. There was a positively correlation between BASMI score with mSASSS in patients with AS. There was an inversely correlation between dkk-1 levels with lumbar total, hip total and femur neck bone mineral density (BMD) in patients with RA. Conclusion: Levels of dkk-1 in patients with AS was inversely correlated with BASMI, on the other hand BASMI had a strongly positive correlation with mSASSS. Therefore, these findings suggest that lower dkk-1 levels in patients with ankylosing spondylitis may play a role in new bone formation. Key words: Ankylosing spondylitis, Dickkopf-1, sclerostin, anti-TNF treatment, new bone formation