Background Due to its effect on the immune system and antioxidant features melatonin (MLT) has attracted a great deal of attention in recent years. Its role in pathogenesis of chronic inflammatory diseases have been studied. However only few studies have investigated its role in Ankylosing Spondylitis (AS).
Objectives The aim of this study is to investigate the circadian rhythm of MLT and its relationship with disease activity, quality of life and enthesitis score in AS patients.
Methods Sixteen AS patients diagnosed according to the Modified New York 1984 criteria and 16 age and sex matched healthy controls were enrolled in the study. Serum MLT levels were measured at 20:00, 03:00 and 08:00 via melatonin direct radioimmunoassay kit (LDN BA R-3300) in both groups. Bath AS Disease Activity Score (BASDAI), Bath AS Functional Index (BASFI), Maastricht AS Enthesitis Score (MASES) and AS Quality of Life (ASQoL) were calculated in AS group. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels were measured, duration of morning stiffness was questioned
Results The mean morning (08:00) and evening (20:00) MLT levels were significantly higher in the patient group (34.00±13.51 pg/ml versus 24.88±7.10 pg/ml and 34.25±7.92 pg/ml versus 27.75±8.25 pg/ml respectively) (p<0.05). The mean MLT level at night (03:00) was also higher in AS group but the difference did not reach statistical significance. (98.81±39.16 pg/ml versus 73.94±30.49 pg/ml) (p:0.054). A significant positive correlation was found between morning and night MLT levels and duration of morning stiffness, BASDAI, BASFI, ASQoL and MASES scores. No significant correlation was found between evening MLT levels and these parametres. Also no correlation was found between acute phase reactants (ESR,CRP) and the MLT levels.(Table)
Conclusions Ankylosing Spondylitis patients have higher melatonin levels and the melatonin levels of AS patients are associated with the duration of morning stiffness, disease activity, quality of life and enthesitis scores. We suggest that our results should be supported by studies performed in wider study populations also involving patients with non-radiographic axial spondyloarthritis as a subgroup and with more frequent melatonin measurements performed especially at night in order to assess the exact circadian rhythm of melatonin in spondyloarthritis.
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Disclosure of Interest None declared