Introduction: Interleukin-18 (IL-18) is a strong proinflammatory cytokine that its increased levels are associated with obesity, metabolic syndrome, insulin resistance, dyslipidemia, and atherosclerosis. Thus, the purpose of this study was to investigate the relationships between serum interleukin-18 concentration with acylated ghrelin, growth hormone, insulin resistance, and lipid profile in obese and lean men. Methods: In this semi-experimental study, ninety obese (body mass index ≥30 kg/m2) and ninety lean men (body mass index ≤ 18.5 kg/m2) were selected. After 12 h fasting, blood samples were collected and general characteristics of subjects were assessed. The study data was then analyzed by Pearson’s correlation coefficient with the significance level of P<0.01. Results: Serum levels of IL-18 were positively correlated with insulin resistance index (HOMA-IR) (obese: r=0.35, p=0.000, lean: r=0.31, p=0.009) and triglyceride (obese: r=0.19, p=0.000, lean: r=0.11, p=0.002), while negatively correlated with high-density lipoprotein (obese: r=-0.23, p=0.003, lean: r=-0.14, p=0.006). No significant correlations were observed between serum IL-18 levels with acylated ghrelin, growth hormone, total cholesterol, and low-density lipoprotein. Conclusions: The study findings revealed that in both groups of obese and lean men, serum levels of IL-18 positively correlated with insulin resistance and triglyceride, and negatively correlated with high-density lipoprotein. Furthermore, within obese individuals that have elevated IL-18 levels, this can be associated with disorder in glycemic control and lipid profile, and thus, with increased risk of cardiovascular and metabolic disorders. IL-18 levels do not appear to have any correlations with acylated ghrelin, growth hormone, total cholesterol, and low-density lipoprotein.

Keywords: Acylated ghrelin, Growth hormone, Insulin resistance, Interleukin, Lipid profile

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