Increased Levels of Human Myeloperxidase (MPO) and Neutrophil Lipocalin (HNL/NGAL) in Childhood Asthma

Purpose: Myeoloperoxidase (MPO) and human neutrophil lipocalin (HNL/NGAL) are stored in neutrophil granulocytes and secreted upon activation of the cells. They have been proposed to reflect the degree of inflammation in the airways. Methods: 86 children with asthma and 59 control subjects were enrolled. Concentration of human MPO and HNL/NGAL were measured in sputum supernatants using ELISA. The characteristics of subjects include results of spirometry, methacholine challenge test and atopy. Results: Sputum MPO and HNL/NGAL concentration were significantly higher in children with asthma than in control (p=0.032 and p=0.001, respectively). Sputum MPO and HNL/NGAL levels were positively correlated with each other in all subjects (r=0.570, p<0.001). Among asthma patients, children with moderate-to-severe persistent asthma showed higher sputum MPO (p=0.001) and HNL/NGAL (p=0.004) levels than those with intermittent and mild persistent asthma. Sputum neutrophil counts, not sputum eosinophils, in asthma patients were positively correlated with concentration of MPO (r=0.247. p=0.03) and HNL/NGAL (r=0.275. p=0.011). Positive significant correlations of FeNO were also found with MPO (r=0.345, p=0.016) and HNL/NGAL (r=0.294, p=0.038) levels in sputum. Conclusion: Airway neutrophilic inflammation plays an important role in pediatric asthma and its severity. Sputum MPO and HNL/NGAL reflecting neutrophil activation could be a good assessment for asthma severity in children.