Role of acidic mammalian chitinase and chitotriosidase in nasal polyps

OBJECTIVE: Chitin is a recognition element for tissue infiltration by innate cells implicated in allergy and helminth immunity, and this process can be negatively regulated by vertebrate chitinases. Acidic mammalian chitinase (AMCase) and chitotriosidase (ChT) have chitinolytic activity, but little is known about their roles in nasal polyps. STUDY DESIGN: A prospective controlled study. SETTING: A tertiary referral center. SUBJECTS AND METHODS: Nineteen subjects with nasal polyps and 12 subjects with deviated nasal septums were recruited to obtain inferior turbinate mucosa samples. The expression levels of AMCase and ChT were compared in nasal polyp and inferior turbinate tissue samples. The tissue samples were analyzed by reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemical staining. RESULTS: AMCase and ChT were detected in all nasal polyps and inferior turbinate tissues. AMCase and ChT messenger RNA and protein expression were significantly higher in nasal polyps than in inferior turbinate tissues. In nasal polyps, AMCase-positive and ChT-positive cells were detected in the epithelium, inflammatory cells, and submucosal gland. CONCLUSIONS: AMCase and ChT may be important mediators in the pathogenesis of nasal polyps. Nasal polyps appear to have elevated levels of chitinases, and the presence or growth of chitin-containing pathogens might enhance chitinase expression, resulting in nasal polyp formation and growth in susceptible individuals. (C) 2009 American Academy of Otolaryngology-Head and Neck Surgery Foundation. All rights reserved.