A recent study shows, that YKL-40 is upregulated in patients with chronic obstructive pulmonary disease (COPD)[21], where it seems to contribute to tissue inflammation and remodelling by activating alveolar macrophages and sustaining their synthesis of proinflammatory and fibrogenic chemokines and metalloproteinases [21]. Here, CHI3L1 is linked to chronic obstructive pulmonary disease.