Introduction: Research on obesity, which results from excessive food consumption and sedentary lifestyle, has focused on increasing energy expenditure. Recently, muscle tissue is being investigated as an endocrine active organ, secreting molecules called myokines. Multiple studies have been performed to assess myokine levels in various disorders, including polycystic ovary syndrome (PCOS) and metabolic syndrome. Irisin and Meteorin-like protein (Metrnl) are particles which, among others, are suggested to play an important role in adipose tissue browning and improving insulin sensitivity.
Material and methods: The study population consisted of 31 women with PCOS and 18 healthy individuals. PCOS was diagnosed based on revised 2003 Rotterdam criteria. Multiple anthropometrical, hormonal, and biochemical parameters were assessed, including oral glucose tolerance test and body composition with dual energy X-ray absorptiometry. Serum levels of irisin and Metrnl were measured by enzyme-linked immunosorbent assay (ELISA).
Results: There were no differences between the PCOS and control groups according to age, body mass index (BMI), waist-to-hip ratio (WHR), fasting glucose, homeostasis model assessment of insulin resistance (HOMA-IR), or body mass composition. Assessment of Metrnl and irisin concentrations revealed no significant differences between PCOS and healthy women. The irisin level was negatively correlated with BMI, body fat mass, fasting glucose, and insulin concentrations. No relationship between Metrnl level and metabolic parameters was found.
Conclusions: Although irisin seems to be a promising biomarker, inconsistent research limits its value in clinical use in the assessment or treatment of obesity. Metrnl level was not affected in the study population, but it might be connected to the severity of metabolic disturbances.
Keywords: Meteorin-like protein; Metrnl; PCOS; irisin; metabolic disturbances; myokines; obesity.