Adipose tissue, serum adipokines, and ghrelin in patients with ankylosing spondylitis

Adipokines such as leptin and adiponectin are involved in the regulation of inflammation. Ghrelin, a gastric peptide playing a role in the appetite regulation, possesses anti-inflammatory properties. In this study, we evaluated the circulating levels of adipokines (leptin as potential proinflammatory and adiponectin as anti-inflammatory marker) and ghrelin and the fat mass in patients with ankylosing spondylitis (AS). Serum leptin, adiponectin, and ghrelin were evaluated in 53 AS patients with active disease (mean Bath Ankylosing Spondylitis Disease Activity Index >40) and 35 controls. Fat and lean masses were determined using dual-energy x-ray absorptiometry. Fat and lean masses did not differ between patients and controls. Ankylosing spondylitis patients had lower leptin levels compared with controls, even after adjustment for fat mass (AS vs controls: leptin, 7.6 +/- 1.3 ng/mL vs 10.3 +/- 1.5 ng/mL; leptin [in nanograms per milliliter]/fat mass [in kilograms], 0.28 +/- 0.04 vs 0.44 +/- 0.04; P = .006 and P = .0003, respectively). Serum adiponectin did not differ between patients and controls, whereas circulating ghrelin was higher in AS patients (1354.6 +/- 70.5 pg/mL vs 1008.0 +/- 82.5 pg/mL; P = .001). However, all these results were significant only for male patients. No correlation was found between leptin and adiponectin, and erythrocyte sedimentation rate, C-reactive protein levels, tumor necrosis factor alpha, or Bath Ankylosing Spondylitis Disease Activity Index. Ankylosing spondylitis patients had no changes in fat mass. Leptin production was reduced in contrast with normal levels of adiponectin. These adipokine results, together with high serum ghrelin levels, may influence the inflammatory response in AS.