RATIONALE: Proton channel activity is required for maintaining NAPDH oxidase function during respiratory burst in phagocytes. Recently, the proton channel required for respiratory burst in neutrophils was molecularly identified as HVCN1. Furthermore, HVCN1-/- neutrophils have a migration defect in vitro. Thus, we hypothesized that HVCN1 is expressed by eosinophils and required for extracellular respiratory burst, eosinophil migration and recruitment into the lung in allergic airway inflammation. METHODS: The development of bone marrow (BM)-derived eosinophils from WT and HVCN1-/- mice and chemotaxis in vitro were examined. Further, eosinophil reactive oxygen species (ROS) production following PMA stimulation was assessed using Lucigenin in BM-derived eosinophils. WT and HVCN1-/- mice were intranasally challenged with Aspergillus fumigatus extract 3 times/week for 3 weeks. 24 hours after last challenge, mice were sacrificed and bronchoalveolar lavage fluid (BALF) was collected. Total BALF cells were counted and morphologically differentiated. RESULTS: We observed similar development of BM-derived eosinophils from WT and HVCN1-/- mice with regard to morphology, cell number and CCR3 and Siglec F co-expression on cell surface, suggesting that HVCN1 is not required for eosinophil development from BM. However, while WT eosinophils produced diphenyleneiodonium (DPI)- and superoxide dismutase (SOD)-inhibitable ROS in response to PMA, HVCN1-/- eosinophils produced significantly less ROS (39.8%Â±5.1%). In contrast, WT and HVCN1-/- eosinophils showed comparable migration in vitro. Moreover, eosinophil accumulation in the BALF from allergen-challenged HVCN1-/- mice was not decreased compared to that of WT mice. CONCLUSIONS: HVCN1 is partially required for ROS production by eosinophils.
Full conference title:
American Academy of Allergy Asthma & Immunology
- AAAAI 2011 (67th)