CHI3L1 and chronic obstructive pulmonary disease: Notably, elevated levels of YKL-40 are observed in a variety of conditions, including asthma, chronic obstructive pulmonary disease (COPD), inflammatory bowel disease (IBD), alcoholic cirrhosis, Alzheimer’s disease, and several types of cancer [24,25,26,27,28,29,30,31,32,33,34,35,36], indicating its potential as a biomarker [3].