The study suggests that circulating serum levels of YKL-40 increased in patients with asthma, compared to those without disease, and correlate with asthma severity. In the study of 253 adult patients, investigators evaluated serum levels of YKL-40 across three asthma and control cohorts.
Based on an exploratory analysis of serum samples of an established cohort of subjects from Yale University, samples were then evaluated from sets of patients at the University of Wisconsin and the University of Paris. Levels of circulating YKL-40 were measured across all cohorts, and findings were correlated with asthma severity, airway expression of the molecule and parameters of airway remodeling.
Data demonstrated that serum YKL-40 levels were significantly elevated in patients with severe asthma compared to the control group. In the Yale cohort, median levels of YKL-40 in the serum from patients with asthma were 69.7ng/ml compared to 58.3ng/ml in those without asthma. Interquartile ranges were 40.0-107.1 and 40.0-73.3, respectively.
Findings in the Yale cohort were subsequently confirmed in the Paris cohort. Median levels of YKL-40 in the serum from patients with asthma were 97.7ng/ml compared to 41.5ng/ml in those without asthma. Interquartile ranges were 26.8-103.5 and 11.5-57.8, respectively. In all three cohorts, levels of circulating YKL-40 correlated to asthma severity.
Data from this early-phase study suggest that serum YKL-40 levels were significantly elevated in patients with severe asthma and that this molecule may be a biomarker for asthma severity, compared to patients with milder disease or to those without asthma. Additionally, a post-hoc analysis suggested that among patients with severe asthma, YKL-40 levels correlated with clinical measurements associated with severe disease, including the frequency of corticosteroid tapers, doses of oral corticosteroids and the frequency of rescue inhaler use.
Marina Pretolani, Denis Diderot Faculty of Medicine, University of Paris, said: “YKL-40 overexpression occurs in patients taking high-dose, long-term inhaled corticosteroids, suggesting that YKL-40 production is refractory to current asthma treatments and, therefore, it may represent an alternative therapeutic target for severe asthma.”