Increased Expression of Acidic Mammalian Chitinase and Chitotriosidase in the Nasal Mucosa of Patients with Allergic Rhinitis

Objectives/Hypothesis: Acidic mammalian chitinase (AMCase) has emerged as an important mediator of allergic asthma in both animal models and in humans. Recently, chitotriosidase has been suggested to play a role in innate immunity because of its phagocytic-specific expression. Thus, AMCase and chitotriosidase may play a role in the pathogenesis of allergic nasal mucosa. The expression and pattern of distribution of AMCase and chitotriosidase were, therefore, determined in normal and allergic nasal mucosa. Study Design: Controlled, prospective study. Methods: Normal inferior turbinate mucosa was obtained in patients who were admitted for augmentation rhinoplasty. Allergic turbinate mucosa was obtained from patients who had perennial allergic rhinitis during septo-turbinate surgery. Reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemistry, and Western blotting were applied to the normal and allergic nasal mucosa. Results: The expression of AMCase and chitotriosidase mRNAs and proteins analyzed by RT-PCR and Western blot were detected in all normal and allergic turbinate mucosa tested. The levels of expression of AMCase and chitotriosidase mRNAs and proteins were increased in allergic turbinate mucosa compared with normal turbinate mucosa. In both normal and allergic turbinate mucosa, AMCase and chitotriosidase were detected in the epithelium, inflammatory cells, and submucosal glands. The staining intensity for AMCase and chitotriosidase was stronger in allergic nasal mucosa than normal nasal mucosa. Conclusions: AMCase and chitotriosidase are constitutively expressed in normal turbinate mucosa, suggesting involvement in defense against chitin-containing pathogens. Upregulation of these chitinases in allergic condition suggests that they may play a role in the nasal allergic reaction like other inflammatory mediators in allergic rhinitis.