Effect of formoterol on eosinophil trans-basement membrane migration induced by interleukin-8-stimulated neutrophils

Background: Neutrophils are often increased in the airways of either chronic severe asthma or acute exacerbations. Neutrophils that have migrated in response to interleukin-8 (IL-8) may lead eosinophils to accumulate in the airways of patients with asthma and possibly aggravate the disease. In this study, we investigated whether formoterol modified 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. Eosinophil TBM was examined using a modified Boyden's chamber technique. Neutrophils were preincubated with or without formoterol (0.1 μM) at 37°C for 30 min. Eosinophils were added to the upper compartment of a chamber with a Matrigel-coated transwell insert. Medium containing preincubated neutrophils and IL-8 was added to the lower compartment of the chamber. After a 90-minute incubation, the eosinophils that had migrated into the lower chamber were calculated using eosinophil peroxidase assays.

Results: A combination of neutrophils and IL-8 significantly induced the eosinophil TBM; formoterol alone had no effect. However, formoterol modestly but significantly attenuated the TBM of eosinophils stimulated with neutrophils and IL-8.

Conclusion: These results suggest that formoterol may act as a therapeutic agent on enhanced eosinophilic inflammation in acute exacerbation or persistent, severe asthma. The effect of formoterol likely involves the inhibition of neutrophil activation.