The role of chitinase-like proteins in allergic inflammation on pediatric adenoid tissue

Chitin is an essential structural component of the fungal cell wall and is present in the exoskeleton of arthropods and the microfilarial sheath of nematodes. Recent findings have not only demonstrated that mammals produce chitinases, but also that increased secretion of chitinases is closely associated with Th2-dominated pathophysiological conditions including infection, fibrosis, allergy and asthma. The purpose of this study is to measure the level of chitinase-like proteins (CLPs) in adenoid tissues from atopic children, and to know its role in allergic inflammation on pediatric adenoid tissues. Forty atopic subjects, who were sensitized to more than one common aeroallergen, and 40 non-atopic subjects undergoing adenotonsillectomy, were recruited. The level of CLPs was measured by ELISA. Immunoassays using adenoid tissue homogenate were performed to quantify the levels of total IgE, eosinophil cationic protein (ECP), mast cell tryptase and Alternaria-specific IgE. Median level of CLPs was tend to be higher in atopics than in non-atopics (p = 0.056). Median level of ECP was significantly higher in atopics than in non-atopics (p < 0.001), while no difference was seen in tryptase. The level of CLPs in adenoid tissues strongly correlated with ECP or tryptase level. In addition, median level of CLPs was significantly higher in children showing positive response for Alternaria-specific IgE than in children with negative response. In conclusion, chitinase showed close relationships with ECP or tryptase in allergic inflammation on pediatric adenoid tissues, and increased locally in fungal allergen sensitized children.