Relationship between Respiratory Function and Serum Interleukin‑6 Level in Nonobese and Obese Male Adult Subjects
Background and Aim: Proinflammatory cytokines may be the crucial factor in link between respiratory function decline and obesity. The aim of the present study is to investigate the relationship between respiratory function and serum interleukin‑6 (IL‑6) level in nonobese and obese male adult subjects. Methods: A community‑based cross‑sectional comparative study was carried out in 30 nonobese (body mass index [BMI] = 22.99 ± 1.08 Kg/m2; waist circumference [WC] = 75.27 ± 4.08 cm), 34 generally obese (BMI = 30.88 ± 0.87 Kg/m2; WC = 84.03 ± 3.02 cm), and 37 centrally obese subjects (BMI = 31.59 ± 2.11 Kg/m2; WC = 96.08 ± 3.35 cm). Spirobank II spirometer was used to measure respiratory function (forced expiratory volume in 1 s [FEV1], forced vital capacity [FVC], FEV1/FVC, peak expiratory flow rate, and average forced expiratory flow between 25% and 75% of FVC). Serum IL‑6 level was measured by enzyme‑linked immunosorbent assay. For comparative studies, ANOVA test was used for normally distributed data and Kruskal–Wallis test was used for screwed data. Pearson’s correlation and Spearman’s rho test were used for correlation studies. Results: The percentage of predicted value of all respiratory function parameters of generally obese group as well as centrally obese group was significantly lower than that of nonobese group (P < 0.05). Median and interquartile range of serum IL‑6 level of nonobese group, generally obese group, and centrally obese group were 10 (10–11) pg/mL, 32 (17.5–65) pg/mL, and 52 (25–65) pg/mL, respectively. There were significant differences between the groups (P < 0.001). There was a significant positive correlation between serum IL‑6 levels and BMI (r = 0.519, n = 101, P < 0.001) as well as WC (r = 0.547, n = 101, P < 0.001). All respiratory function parameters were significantly and negatively correlated with anthropometric measurements (BMI and WC) as well as serum IL‑6 level. Respiratory functions were more significantly and strongly correlated with anthropometric parameters than serum IL‑6. Conclusion: It was concluded that reduced respiratory function in obesity might be due to mechanical effect of obesity and systemic low‑grade inflammatory effect of obesity is partly contributed.