YKL-40 as a New Biomarker in Asthmatic Children and Asthmatic Exacerbation. Its Role and Correlations with Eosinophil's Percentage and Serum IgE Level

Abstract Background: YKL-40 is a member of the mammalian chitinase like protein class of 40 Kda (kilo Dalton) heparin binding glycoprotein. Its name is derived from the protein's molecular weight and three N-terminus amino acids (tyrosine [y], lysine [k] and leucine [l]). YKL-40 is secreted by various cell-types including macrophages, chondrocytes, and some types of cancer cells. The exact physiological role of YKL-40 is not known, but it has been implicated in cell development, inflammatory disease such as asthmaand cancer progression. Aim of Study: This study was to investigate whether serum YKL-40 were increased in Asthmatic children and identify its correlation with acute exacerbation, total IgE, blood Eosinophil percentage (EO%) and Pulmonary Function (PF). We measured serum YKL-40 levels, EO%, and serum IgE in 30 children with Asthma as well as in 20 apparently healthy controls from the communities surrounding AL-Salama Hospital, EL-Khobar district, Saudi Arabia. Pulmonary Func-tion (PF) of Asthmaticpatients was also measured. Patients and Methods: Our data showed that the serum YKL-40 was significantly elevated in patients with Asthma (77.66ng/mL) compared with control (55.16ng/mL) (p=0.001) and when Asthma patients were stratified, serumYKL-40 levels in exacerbation group were significantly higher (83.72ng/ mL) than those in stable Asthmatic group (77.66ng/mL) (p=0.043). Results: In addition, serum YKL-40 was correlated posi-tively with the level of IgE (with r=0.298 and p=0.018) and EO% (with r=0.272 and p=0.032) but negatively correlated to pulmonary functions as Forced Expiratory Volumein 1st second (FEV1) (with r=–0.044 and p=0.0001). Thus, we conclude that YKL-40 is found significantly high in the serum of asthmatic childrenand its level correlates with exacerbation attacks, indicating that high levels of serum YKL-40 may be biological characteristic of the asthma exac-erbation. Conclusion: In our study, we conclude that serum YKL-40 level are increased in asthmatic children patients and its level correlates with exacerbation attacks indicating that YKL-40 may be either a cause or a new biomarker for asthma and its disease severity.