64 Effect of Formoterol on Eosinophil Trans-Basement Migration Induced by Interleukin-8-Stimulated Neutrophils

BACKGROUND: Neutrophils are often increased in the airways of either chronic severe disease or acute exacerbation of asthma. Neutrophils migrated in response to interleukin-8 (IL-8) may lead eosinophils to accumulate in the airways of asthma and possibly aggravate this disease. In this study, we investigated whether formoterol modify the trans-basement membrane migration (TBM) of eosinophils stimulated with neutrophils and IL-8. METHODS: Neutrophils and eosinophils were isolated from peripheral blood obtained from healthy donors. The TBM of eosinophils was examined using a modified Boyden's chamber technique. Neutrophils were preincubated with or without formoterol (0.1 μM) at 37°C for 30 minutes. Eosinophils were added to the upper compartment of a chamber with a Matrigel-coated transwell insert. Medium that contained preincubated neutrophils and IL-8 was added to the lower compartment of the chamber. After 90 minute incubation, migrated eosinophils in the lower chamber were calculated using eosinophil peroxidase assays. RESULTS: A combination of neutrophils and IL-8 significantly induced TBM of eosinophils. Formoterol by itself did not modify the TBM of eosinophils. However, formoterol significantly attenuated TBM of eosinophils stimulated with neutrophils and IL-8. CONCLUSIONS: These results suggest that formoterol may act as a therapeutic agent on enhanced eosinophilic inflammation in acute exacerbation or persistent severe disease of asthma. This effect of formoterol likely involves inhibition of activation of neutrophils.