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Pediatr Allergy Immunol. 2019 Sep 5. doi: 10.1111/pai.13119. [Epub ahead of print]

Serum chitinase-like protein YKL-40 is linked to small airway function in children with asthmatic symptoms.

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Department of Allergology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.



Lung function impairment among asthmatics begins in early life and biomarkers for identifying this impairment are needed. The chitinase-like protein YKL-40 has been associated with asthma and lung function in adults but studies in children have yielded conflicting results. We evaluated the potential of YKL-40 and other systemic biomarkers for identifying asthmatic lung function deficits in children.


We determined the levels of serum YKL-40, periostin, and high-sensitivity C-reactive protein (hs-CRP) from the blood samples of 49 children with asthmatic symptoms. Lung function was assessed with impulse oscillometry (IOS) and spirometry, combined with an exercise challenge and a bronchodilator test. Fractional exhaled nitric oxide was measured at multiple flow rates.


Serum levels of YKL-40 showed significant correlations with most IOS indices at baseline (p=0.008-0.039), but there was no association between YKL-40 and spirometry parameters. Neither periostin nor hs-CRP were associated with baseline lung function. Children with a significant response in either the exercise challenge or the bronchodilator test had increased serum levels of YKL-40 (p=0.003) and periostin (p=0.035). YKL-40 correlated significantly with the blood neutrophil count (rs =0.397, p=0.005) but was not associated with biomarkers of eosinophilic inflammation.


Serum YKL-40 is a potential biomarker for lung function deficits in children with asthmatic symptoms. These deficits appear to be focused on small airways and may remain undetected with spirometry. This article is protected by copyright. All rights reserved.


YKL-40; airway resistance; asthma; respiratory function tests; spirometry


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