Fetuin-A is related to syndesmophytes in patients with ankylosing spondylitis: a case control study

OBJECTIVES: New bone formation is one of the hallmark characteristics of ankylosing spondylitis, which is thereby associated with syndesmophytes. Fetuin-A is a molecule that is abundantly found in calcified tissues and it shows high affinity for calcium phosphate minerals and related compounds. Considering the role of fetuin-A in the regulation of calcified matrix metabolism, we compared the fetuin-A levels in ankylosing spondylitis patients with syndesmophytes with those in patients without syndesmophytes and in healthy controls. We also studied other biomarkers that are thought to be related to syndesmophytes. METHODS: Ninety-four patients (49 patients without syndesmophytes, 67.3% male, 40.7±8.7 years; 45 patients with syndesmophytes, 71.1% M, 43.9±9.9 years) and 68 healthy controls (44.2±10.6 years and 70.6% male) were included in this study. Syndesmophytes were assessed on the lateral radiographs of the cervical and lumbar spine. The serum levels of fetuin-A, dickkopf-1, sclerostin, IL-6, high-sensitivity C-reactive protein and bone morphogenetic protein-7 were measured with an enzyme-linked immunosorbent assay. RESULTS: Patients with syndesmophytes had significantly higher levels of fetuin-A compared with patients without syndesmophytes and controls (1.16±0.13, 1.05±0.09 and 1.08±0.13 mg/ml, respectively). However, fetuin-A was not different between the patients without syndesmophytes and controls. Bone morphogenetic protein-7 was significantly lower; dickkopf-1 was significantly higher in patients with ankylosing spondylitis compared with controls. The sclerostin concentrations were not different between the groups. In regression analysis, fetuin-A was an independent, significant predictor of syndesmophytes. CONCLUSION: Our results suggest that fetuin-A may a role in the pathogenesis of bony proliferation in ankylosing spondylitis. .

Bone and Cartilage Turnover Markers, Bone Mineral Density, and Radiographic Damage in Men with Ankylosing Spondylitis

PURPOSE: To determine the levels of bone and cartilage turnover markers in men with ankylosing spondylitis (AS) and to investigate their associations with disease activity, bone mineral density, and radiographic damage of the spine. PATIENTS AND METHODS: This cross-sectional study enrolled 35 men with newly diagnosed AS. The bone mineral densities (BMD) of their lumbar spines and proximal femurs, Bath AS Disease Activity Index (BASDAI), and Bath AS Radiographic Index (BASRI) were evaluated. Urinary C-terminal telopeptide fragments of type I collagen (CTX-I) and type II collagen (CTX-II) levels were determined by enzyme-linked immunosorbent assay, and serum levels of bone-specific alkaline phosphatase (BALP) and osteocalcin were determined by an enzyme immunoassay. Levels of biochemical markers were compared with those of 70 age-matched healthy men. RESULTS: Patients with AS had significantly higher mean urinary CTX-I and CTX-II levels than control subjects (p < 0.05). Elevated urinary CTX-I levels correlated well with BASDAI, femoral BMD, and femoral T score (p < 0.05), and elevated urinary CTX-II levels correlated well with spinal BASRI (p < 0.05) in patients with AS. Mean serum BALP and osteocalcin levels did not differ between patients and controls and did not show any significant correlations with BMD, BASDAI, or BASRI in men with AS. Conclusions: Elevated CTX-I reflects disease activity and loss of femoral BMD while elevated CTX-II levels correlate well with radiographic damage of the spine, suggesting the usefulness of these markers for monitoring disease activity, loss of BMD, and radiographic damage in men with AS.