Altered expression of microRNAs targeting Dkk-1 in peripheral blood mononuclear cells of patients with ankylosing spondylitis.

INTRODUCTION: Ankylosing spondylitis (AS) is a chronic inflammatory disease characterised by new bone formation, and Dickkopf homologue 1 (Dkk-1) may contribute to the ankylosis of the sacroiliac joint as a main regulator of the Wingless (Wnt) pathway. Increasing evidence shows that microRNAs targeting Dkk-1 might play a critical role in the pathogenesis of rheumatic diseases. We aim to investigate alterations in expression of miRNAs targeting Dkk-1 in AS patients in this study. MATERIAL AND METHODS: The peripheral blood mononuclear cells (PBMCs) of 20 AS patients and 20 normal controls were collected in our study. Three miRNAs targeting DKK1 including miR-29a, miR-335, and miR-363 were selected and quantitative real-time PCR was used to identify the expression of the three miRNAs in these samples. Correlation analysis was conducted between altered miRNA expression and erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Function Index (BASFI), and mSASSS (modified Stoke Ankylosing Spondylitis Spinal Score). RESULTS: The expression of miR-29a was significantly higher in AS patients than in healthy controls (p < 0.01), while no significance was observed in the expression of miR-335 and miR-363 between AS patients and healthy controls (p > 0.05). No correlation was observed between miR-29a and ESR, CRP, BASDAI, and BASFI (p > 0.05). The elevated miR-29a expression was correlated with disease duration and mSASSS (p < 0.05). CONCLUSIONS: MiR-29a might be a useful marker in AS new bone formation and contributes to the regulation of Dkk-1 in Wnt signalling.

MiR-29a and Messenger RNA Expression of Bone Turnover Markers in Canonical Wnt Pathway in Patients with Ankylosing Spondylitis.

BACKGROUND: Recent studies showed that the canonical Wnt pathway and miR-29a play important roles in the pathogenesis of bone formation. We studied the levels of miR-29a and messenger RNA (mRNA) of bone turnover markers in the canonical Wnt pathway in ankylosing spondylitis (AS). METHODS: The levels of miR-29a and mRNA of bone turnover markers in canonical Wnt pathway from peripheral blood mononuclear cells were determined by real-time quantitative polymerase chain reaction in 38 patients with AS and 32 healthy controls. Correlation analysis was conducted between the levels of miR-29a and mRNA and clinical measurements using Spearman's correlation test. RESULTS: Compared to healthy controls, the levels of miR-29a, Dickkopf (DKK)-1, ß-catenin and Runx2 mRNA were significantly higher in AS patients (p < 0.05). In contrast, the levels of Gsk-3ß mRNA was significantly lower in AS patients than that in healthy controls (p < 0.05). Gsk-3ß mRNA was positively correlated with ß-catenin mRNA expression (p < 0.05) and no other correlation was observed between any other markers (p > 0.05). Only DKK-1 mRNA expression was negatively correlated with disease course (p < 0.05) and no other correlation was observed between markers and clinical measurements (p > 0.05). CONCLUSIONS: The osteoblastic marker miR-29a and downstream mRNA of canonical Wnt signaling was upregulated in AS, suggesting their possible role in new bone formation in AS.

Alteration of Bone Turnover Markers in Canonical Wingless Pathway in Patients With Ankylosing Spondylitis.

OBJECTIVES: This study aims to determine the levels of bone turnover markers in canonical wingless pathway in patients with ankylosing spondylitis (AS) and the correlation with disease activity indexes. PATIENTS AND METHODS: We recruited a total of 43 AS patients (34 males, 8 females; mean age 36.8±9.3 years; range 22 to 62 years) and age- and sex-matched 42 healthy controls (32 males, 10 females; mean age 36.1±9.7; range 24 to 59 years). Serum levels of components of canonical wingless pathway including Dickkopf-1, glycogen synthase kinase-3ß, ß-catenin, alkaline phosphatase, and osteocalcin were detected using enzyme- linked immunosorbent assay method. All patients were assessed in terms of erythrocyte sedimentation rate, C-reactive protein, Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, Ankylosing Spondylitis Disease Activity Score, and the modified Stoke's Ankylosing Spondylitis Spine Score. Pearson's correlation test was used to analyze the correlation between serum bone turnover markers and clinical assessment indexes. RESULTS: No significant difference was observed between AS patients and healthy controls for the levels of glycogen synthase kinase-3ß, ß-catenin, alkaline phosphatase, and osteocalcin, respectively (p>0.05). The level of Dickkopf-1 was significantly higher in AS patients (1914.5±407.8 pg/mL) than in healthy controls (1729.1±352.9 pg/mL) (p<0.05). There was no correlation between high Dickkopf-1 level and any of the clinical parameters contributing to inflammation or bone formation. However, the correlation between osteocalcin and disease duration was significant in AS patients (r=0.323, p=0.034). CONCLUSION: Alteration of bone turnover markers in canonical wingless pathway was observed in AS. This might partially explain the complicated mechanism of bone formation in the disease.