Trans-Basement Membrane Migration of Eosinophils Induced By LPS-Stimulated Neutrophils from Human Peripheral Blood in Vitro.
Sunday, March 6, 2016
South Exhibit Hall H (Convention Center)
Rationale: In the airways of severe asthmatics, an increase of neutrophils and eosinophils is often observed despite high-dose corticosteroid therapy. We previously reported that IL-8-stimulated neutrophils induced trans-basement membrane migration (TBM) of eosinophils, suggesting the link between neutrophils and eosinophils. Concentrations of lipopolysaccharide (LPS) in the airway increase in severe asthma. As neutrophils express Toll-like receptor (TLR) 4 and can release chemoattractants for eosinophils, we investigated whether LPS-stimulated neutrophils modify eosinophil TBM. Methods: Neutrophils and eosinophils were isolated from peripheral blood of healthy volunteers or severe asthmatics. Eosinophil TBM was examined using a modified Boyden’s chamber technique. Eosinophils were added to the upper compartment, and neutrophils and LPS were added to the lower compartment. Migrated eosinophils were measured by eosinophil peroxidase assays. Results: LPS-stimulated neutrophils induced eosinophil TBM (about 10 fold increase), although LPS or neutrophils alone did not. A leukotriene B4 receptor antagonist, a platelet-activating factor receptor antagonist, or an anti-TLR4 antibody decreased eosinophil TBM enhanced by LPS-stimulated neutrophils by almost half. Neutrophils from severe asthmatics induced eosinophil TBM, and lower concentrations of LPS augmented neutrophil-induced eosinophil TBM. Conclusions: These results suggest that the combination of neutrophils and LPS leads eosinophils to accumulate in the airways, possibly involved the pathogenesis of severe asthma.