Interleukin-37 and interleukin-39 as novel immunometabolic biomarkers in metabolic syndrome: A cross-sectional study

Metabolic syndrome (MetS) is characterized by abdominal obesity, dyslipidemia, hypertension, and insulin resistance, all driven by chronic low-grade inflammation. This study aimed to evaluate serum interleukin-37 (IL-37) and interleukin-39 (IL-39) levels as potential immunometabolic biomarkers in MetS. Eighty adults (40 MetS patients, 40 healthy controls) were enrolled based on NCEP ATP III criteria. Anthropometric, biochemical, and hormonal parameters were assessed. Serum IL-37 and IL-39 concentrations were measured using ELISA. Statistical analyses included t-tests, Pearson correlations, logistic regression, and receiver operating characteristic curve analysis. Both IL-37 and IL-39 levels were significantly elevated in MetS compared with controls (P <.001). Logistic regression revealed that each 1 pg/mL increase in IL-37 and IL-39 was associated with 1.01-fold (P = .017) and 1.06-fold (P = .001) higher odds of MetS, respectively. receiver operating characteristic analysis showed excellent discriminative ability for IL-39 (AUC = 0.96; 95% confidence intervals: 0.91-1.00) and good accuracy for IL-37 (AUC = 0.82; 95% confidence intervals: 0.73-0.91). Among classical parameters, waist circumference (AUC = 1.00), TG (AUC = 0.93), and fasting glucose (AUC = 0.88) showed the strongest diagnostic power. HDL cholesterol exhibited inverse association (AUC = 0.83), while systolic and diastolic blood pressure showed moderate accuracy (AUC = 0.85 and 0.71, respectively). IL-37 and IL-39 were elevated in individuals with MetS and showed strong discriminative performance, particularly IL-39. These cytokines may reflect underlying immunometabolic alterations and could provide complementary information alongside established metabolic parameters. However, given the cross-sectional design and modest sample size, these findings should be considered exploratory and require validation in larger, longitudinal studies to determine their clinical relevance.