Background Adipomyokines are proteins that are synthesized by and secreted from both skeletal muscle and adipose tissue, and show their effects through autocrine, paracrine or endocrine pathways (1). Irisin, a novel adipomyokine, is secreted in association with exercise from the skeletal muscle, and from the white fat tissue to help the brown fat tissue gain the energy expenditure phenotype (2). There is evidence that the irisin is associated with metabolic syndrome (MetS) and cardiovascular risk (3,4).
Objectives Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD) and MetS compared with the general population (5,6). The aims of this study were to assess the serum level of irisin, and the possible relationships of irisin with disease activity in patients with RA.
Methods Eighty four consecutive RA patients fulfilling the 2010 ACR/EULAR RA Classification Criteria were included in the study. Fifty age- and sex-matched healthy volunteers were enrolled as the control group. Disease duration, medications, history of traditional risk factors of CVD and demographic data of patients were noted. Body Mass Index (BMI) was calculated as “weight (kg)/height (m)2”. HbA1c, lipid profile, insulin were measured. Insulin resistance was assessed with the Homeostasis Model Assessment (HOMA) Index. RA disease activity was assessed by disease activity score based on evaluation of 28 joints (DAS28). Serum irisin level was assessed by ELISA. Measurement of carotid intima media thickness by carotid doppler ultrasonography was performed by a radiologist for cardiovascular risk assessment.
Results There was no significant difference between the groups in terms of BMI (p=0,20), HbA1c (p=0,15), lipid profiles (p<0.05), insulin resistance (p=0.72) and carotid intima-media thickness (p=0.216).
Serum irisin levels were found to be significantly lower in RA patients (20,65 (minimum:16,94- maximum:99,35) ng/mL) than healthy controls (37,56 (18,37–84,70) ng/mL) (p<0.001). There was no relationship between RA disease activity and irisin levels.
Conclusions This study showed that irisin was significantly lower than controls. Irisin may be responsible for increased cardiovascular risk in RA patients. But before a definite judgment; prospective studies with a larger sample size assessing the exercise behaviour of patients and the presence of CVD are necessary.
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Disclosure of Interest None declared