Airway eosinophilic inflammation, body weight and symptoms in COPD over 4 years of follow-up

<b>Background:</b> Chronic eosinophilic inflammation could play a role in COPD pathogenesis. Obesity and COPD mutually aggravate the deterioration of lung function. The association between airway eosinophils, body weight and longitudinal outcomes in COPD is unexplored. <b>Aim:</b> To assess the role of airway eosinophils and evaluate the relationship between body mass index (BMI), symptoms and longitudinal lung function trajectory in patients with COPD. <b>Method:</b> The 127 participants, grouped into non-smokers, smokers and COPD, were followed for 4 years. Based on BMI and occurrence of respiratory symptoms, the subjects were divided into lean (BMI &lt;25 kg/m2, n=44), overweight (25-30 kg/m2, n=53) and obese (&gt;30 kg/m2, n=30) groups and asymptomatic and symptomatic (n=50 and n=77) groups, respectively. Sputum eosinophils and neutrophils were counted from cytospins, and neutrophil gelatinase-associated lipocalin (NGAL) was measured by ELISA. The associations of sputum NGAL with longitudinal decline in lung function was analyzed. <b>Results:</b> Sputum eosinophil levels were increased in overweight-obese COPD and symptomatic COPD compared to smokers (n=0.015 and p=0.044, respectively), but not in lean patients. Sputum NGAL levels were increased in COPD compared with smokers (p&lt;0.05) independently of BMI. Eosinophils in sputum were negatively correlated with declined forced expiratory volume-one second (FEV1) % after 4-years in symptomatic COPD (p=0.031). <b>Conclusion:</b> Airway eosinophil counts could be useful in the assessment of risk and progression in COPD, particularly in symptomatic and obese subjects.