Neutrophilic airway inflammation and association with bacterial lipopolysaccharide in children with asthma and wheezing.

Asthma is a leading chronic childhood illness in the US. To gain further insight into the pathophysiology of childhood asthma, we studied markers of airway inflammation and possible triggers such as bacterial lipopolysaccharide (LPS) in 18 children with chronic asthma and persistent wheezing who underwent clinically indicated bronchoscopy and bronchoalveolar lavage (BAL). We predominantly found neutrophilic airway inflammation associated with increased levels of IL-8, metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP-1) and MMP-9/TIMP-1 ratio. A significant correlation was found between levels of LPS in BAL and airway neutrophils in BAL from a subgroup of children who had a tendency of increased levels of MMP-9 and TIMP-1, suggesting that increased LPS levels in BAL may contribute to chronic airway inflammation and early remodeling. Our data highlight the importance of defining chronic triggers of early airway inflammation in children and characterizing their inflammation, considering the use of bronchoscopy and BAL. Increased knowledge of airway inflammation in children may help prevent a more severe asthma phenotype and lead to environmental control measures and new treatment strategies to intervene against the establishment of irreversible inflammation. Pediatr Pulmonol. 2008; 43:916–923. © 2008 Wiley-Liss, Inc.