YKL-40 as marker of severe lung disease in cystic fibrosis patients

Background: YKL-40 is a chitinase-like protein present in serum of healthy subjects and its levels are increased in several human inflammatory diseases. The aim of this study was to evaluate the levels of both serum and sputum YKL-40 in cystic fibrosis (CF) patients. Methods: Serum and sputum YKL-40 levels were measured in a cohort of twenty-eight patients with a diagnosis of CF and twenty healthy controls. Results: Serum YKL-40 levels were significantly higher in CF patients (88.8 ± 56.7 vs 18.6 ± 2.9 ng/ml, P b 0.001), as well as sputum YKL-40 levels (138.5 ± 132.7 vs 28.2 ± 24.34, P b 0.001) than in healthy controls. Serum YKL-40 levels were closely related to YKL-40 levels assessed in sputum samples (r = 0.71; P b 0.01). Conclusions: YKL-40 is elevated in CF patients and is further elevated during severe exacerbations. Longitudinal studies in infant are needed to establish its role in disease pathogenesis.