The investigation of the role of Acanthamoeba as an allergen in allergic airway inflammation. (P6218)

Abstract

Abstract Asthma patient rapidly have increase recently, but some of these patients do not react to known allergens in skin prick tests, which suggest the presence of unknown environmental allergens. Although Acanthamoeba are abundant in the environment (it also have been often found in human airway cavities) and possess strong proteases enough to elicit allergic airway inflammation, no study has been conducted to determine whether Acanthamoeba can elicit allergic reactions. We repeatedly inoculated Acanthamoeba trophozoites or excretory-secretory (ES) proteins intranasally into mice, and evaluated symptoms and airway immune responses. We found that Acanthamoeba trophozoites or ES proteins reproducibly elicited immune responses resembling allergic airway inflammation. After boiling, which removed protease activity, treatment no longer elevate Th2 related chemokine gene expression in mouse lung epithelial cells, allergic airway inflammation symptoms and Th2 immune responses were remarkably reduced by de-activating proteases. These responses might be not fully elicited through protease activated receptor 2. Furthermore, asthma patients were found to have higher Acanthamoeba specific IgE titers than normal controls. This study suggests that it might be possible to cause allergic airway inflammation by Acanthamoeba (or their products).