Majewski S, et al. - Researchers examined patients with COPD (n=40), healthy smokers (n=20), and healthy never-smokers (n=10) in order to assess the expression of chitotriosidase and YKL-40 in peripheral blood and sputum samples of smokers and patients with COPD. They assessed serum and induced sputum chitotriosidase protein and activity levels, YKL-40 levels, as well as their gene expression in sputum cells and peripheral blood mononuclear cells. Findings revealed the overexpression of chitotriosidase and YKL-40 in peripheral blood and airways in both healthy smokers and patients with COPD, suggesting the potential activation of macrophages, neutrophils, and epithelial cells in relation to smoking.