It has been hypothesized that dysregulated host/microbial interactions play a pivotal role in the pathogenesis of
inflammatory bowel disease. However, the exact mechanisms underlying the induction and perpetuation of the intestinal disorder are unclear. Recently, we unexpectedly discovered significantly upregulated gene expression of
chitinase 3-like-1 in inflamed colon of the
dextran sulfate sodium-induced
colitis model by employing the
DNA-microarray analysis.
Chitinase 3-like-1 has a
chitin binding ability, but lacks the enzymatic activity of lysing microbial cell wall.
Chitinase 3-like-1
protein is mainly expressed in colonic epithelial cells and macrophages in the inflamed colon of
dextran sulfate sodium-induced
colitis.
Chitinase 3-like-1, which can be upregulated after pro-inflammatory
cytokine stimulation, possesses an ability to enhance the adhesion and internalization of intracellular bacteria into colonic epithelial cells. Most importantly, in vivo neutralization of
chitinase 3-like-1 significantly suppressed the development of
dextran sulfate sodium-induced
colitis by dramatically decreasing the bacterial adhesion and invasion into colonic epithelial cells. Furthermore, anti-
chitinase 3-like-1 antibody-treated mice exhibited a significantly lower load of Salmonella typhimurium in peripheral organs as compared to control rabbit
IgG-treated mice. Recently, it has been reported that acidic mammalian
chitinase is expressed in the setting of T helper-2-associated
inflammation and subsequently induces
airway hyperresponsiveness in allergic
asthma patients. In addition, pan-
chitinase inhibitor significantly ameliorates T helper-2-mediated
inflammation and airway
hypersensitivity. These studies provide to be a novel insight into the physiological role of mammalian
chitinases in host/microbial interactions, and inhibition of
chitinase activity would be considered a novel therapeutic strategy of allergic and inflammatory disorders.