Study of serum leptin level in obese and nonobese asthmatic patients

Abstract

Aim: The aim of the study was to investigate serum leptin levels in obese and nonobese asthmatic patients and its change during acute attack and in remission, as well as its relation to the changes in pulmonary functions. Methods: The study was carried out on 55 participants (40 asthmatic patients and 15 controls) who were divided according to BMI into obese [(BMI >30 kg/m2), 20 asthmatic patients and eight controls] and nonobese [(BMI <25 kg/m2), 20 asthmatic patients and seven controls]. All participants were subjected to calculation of BMI, pulmonary function tests, and morning serum leptin level estimation (after at least 8 h of fasting). Results: Serum leptin levels (mean in ng/ml) in obese controls (64 ng/ml) and obese asthmatic patients (80.4 ng/ml during remission and 92.9 during exacerbation) were significantly higher than that in nonobese controls (6.3 ng/ml) and nonobese asthmatic patients (33.8 ng/ml during remission and 48.8 during exacerbation). There was a significant (r = −0.456 and P ≤ 0.05) negative correlation between the change in serum leptin (ng/ml) and the change in forced vital capacity (FVC) (% Predicted) and forced expiratory volume in first second (FEV1) (% Predicted) in obese asthmatic patients, but not in nonobese asthmatic patients. There was a significant positive correlation between BMI (kg/m2) and serum leptin levels (ng/ml) in obese (r = 0.712 and P ≤ 0.05) and nonobese (r = 0.747 and P ≤ 0.05) controls and a higher significant positive correlation in obese (r = 0.94 during exacerbation and r = 0.833 during remission, P ≤ 0.001) and nonobese (r = 0.687 during exacerbation, P ≤ 0.001 and r = 0.488 during remission, P ≤ 0.05) asthmatic patients. Conclusion: Serum leptin levels were higher in all asthmatic patients (more during exacerbation) compared with controls and the values were higher in obese than in nonobese asthmatic patients with a significant negative correlation between the change in serum leptin and the change in FEV1 and FVC in obese asthmatic patients. These findings indicate that leptin is involved in asthma inflammation.