Serum YKL-40 is elevated in children with pneumonia and RSV infection

Background Associations between levels of the chitinase-like protein YKL-40 ( CHI3L1 ) and airway inflammation and remodeling have been shown in adults (Chupp et al. NEJM 2007;357:2016-27) and children (Konradsen et al. JACI 2013; 132:328-35) with asthma. Aim As certain infecting pathogens may be associated with the later development of asthma, we aimed to further investigate the involvement of YKL-40 in asthma by analysing levels in children with different airway infections. Methods Blood was obtained from children with acute rhinovirus (RV)-induced bronchial obstruction (6 mth-4 yr, n=19), respiratory syncytial virus (RSV)-induced bronchiolitis ( CHI3L1 rs4950928 genotype. Results Serum YKL-40 was higher in children with pneumonia and RSV, compared to controls, but unaltered in those with RV. We also confirm that CHI3L1 rs4950928 genotype significantly affects YKL-40 levels whereby the -131 CC allele was associated with elevated serum YKL-40 in the patient groups examined (CC>CG>GG, p Conclusion We show that invasive airway infections, such as bacterial pneumonia and RSV-induced bronchiolitis, are characterized by increased levels of serum YKL-40 in children. This finding further supports the clinical utility of YKL-40 as a biomarker in airway diseases.