Serum Adipokine Levels in Patients With Ankylosing Spondylitis and Their Relationship to Clinical Parameters and Radiographic Spinal Progression

Objective. Adipokines have metabolic and inflammatory functions but can also affect bone metabolism. The purpose of this study was to determine the relationship between serum levels of adiponectin, resistin, and visfatin and markers of inflammation, disease activity, and radiographic spinal progression in patients with ankylosing spondylitis (AS). Methods. Levels of adiponectin, resistin, and visfatin in the serum of 86 AS patients and 25 healthy controls were measured by enzyme-linked immunosorbent assay at baseline. Radiographic spinal progression was determined by the scoring of radiographs of the spine obtained at baseline and after 2 years. Results. Mean (SD) baseline levels of resistin and visfatin were significantly higher in AS patients than in healthy controls (11.6 +/- 10.6 ng/ml versus 6.6 +/- 3.2 ng/ml [P = 0.01] for resistin, and 20.9 +/- 48.3 ng/ml versus 3.4 +/- 2.6 ng/ml [P = 0.001] for visfatin). Adipokine serum levels did not correlate with disease activity or functional indices. Only resistin serum levels correlated with markers of inflammation. Baseline levels of visfatin, but not resistin or adiponectin, were significantly higher in patients with worsening of the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) by 2 units after 2 years (n = 19) as compared to patients without mSASSS worsening (37.7 +/- 57.8 ng/ml versus 16.1 +/- 44.6 ng/ml; P = 0.029) and in patients with syndesmophyte formation/progression (n = 22) as compared to patients without such progression (37.1 +/- 55.3 ng/ml versus 15.3 +/- 44.8 ng/ml; P = 0.023). Visfatin levels of >8 ng/ml at baseline were predictive of subsequent radiographic spinal progression (adjusted odds ratio 3.6 for mSASSS progression and 5.4 for syndesmophyte formation/progression). Conclusion. Serum levels of resistin and visfatin are elevated in AS patients. Elevated visfatin levels at baseline are predictive of subsequent progression of radiographic damage in AS patients.