CHI3L1 and interstitial lung disease: Since then, numerus studies have showed that the serum CHI3L1 levels are increased in patients with other types of ILD, including connective tissue-related ILD (Hozumi et al., 2017; Furukawa et al., 2019; Jiang et al., 2019), sarcoidosis (Johansen et al., 2005; Kruit et al., 2007), cryptogenic tissue pneumonia (Korthagen et al., 2014; Long et al., 2017), asbestosis-ILD (Väänänen et al., 2017), and idiopathic nonspecific interstitial (Korthagen et al., 2014; Long et al., 2017).