Mammalian chitinases belong to the glycosyl hydrolase 18 family based on structural homology and the family
includes a large number of bacterial and eukaryotic chitinases. Among the mammalian chitinases, chitotriosidase (CHIT1)
and acidic mammalian chitinase (AMCase) are capable of hydrolyzing the β-(1, 4)-linkage between the adjacent N-acetyl
glucosamine residues of chitin. CHIT1 is one of the most abundantly secreted proteins, being mainly produced by
activated macrophages and epithelial cells. CHIT1 plays a pivotal role in the context of infectious disease including
malaria and fungi infections as a host defense towards chitin in pathogen’s cell structure and as a diagnostic marker of
disease. In contrast, CHI1 released by activated Kupffer cells in liver could induce hepatic fibrosis and cirrhosis.
Increased serum levels of CHIT1 were observed in patients with many disorders, including Gaucher’s disease, bronchial
asthma, and atherosclerosis. Therefore, CHIT1 seems to have dual (regulatory and pathogenic) roles depending on the
disease and producing cell types during the inflammatory conditions.