YKL-40 levels much lower in children with severe asthma than in adults

Unlike adults, children with severe asthma did not have an association with elevated chitinase-like protein YKL-40 levels, according to recent study results.

Researchers with National Jewish Health, Denver, conducted a prospective, cross-sectional study of 23 adults (mean age, 48.3 years; 64% women) and 19 children (mean age, 12.2 years; 50% females) with severe persistent asthma, 23 children (mean age, 12.1 years; 74% males) with moderate asthma and 19 children (mean age, 11.2 years; 58% males) with mild asthma. Spirometry, exhaled nitric oxide, percutaneous skin testing results to aeroallergens, peripheral eosinophils, serum IgE level and serum YKL-40 levels were measured in each patient.

YKL-40, believed to play a role in inflammation and tissue remodeling, is expressed in the airway of adults with severe asthma and those levels are elevated in the serum, the researchers wrote.

“Compared with adults, children with severe persistent asthma had significantly lower YKL-40 levels [median 26.2 ng/mL, children vs. 62.1 ng/mL, adults; P<.001], higher values for forced vital capacity [94.7%, children vs. 72.5%, adults; P<.001] and [FEV₁; 73.1% of predicted in children vs. 55.1% of predicted in adults; P=.004], higher serum IgE levels and higher exhaled nitric oxide levels,” the researchers reported.

YLK-40 levels showed no correlation in children with increasing asthma severity.

“The present data suggest that serum YKL-40 is neither a marker of severe persistent asthma in children, as seen in adult asthma, nor is it associated with other measurements of asthma severity, lung function, or biomarkers of atopy and eosinophil-mediated inflammation in children,” the researchers concluded. “The pathobiology of severe persistent asthma was distinct in children compared with adults, because this cohort of children with asthma displayed significantly lower YKL-40 levels than the adults with severe persistent asthma, and additional parameters point toward the predominance of T_H2-driven inflammation in childhood asthma. This may suggest an association of YKL-40 levels with a T_H1-driven asthma phenotype in adults.”

Disclosure: See the study for a full list of relevant financial disclosures.