Human peripheral blood eosinophils were isolated by CD16-negative selection method. The effect of AS605240, synthetic PI3K纬 inhibitor on eotaxin-induced adhesion, chemotaxis, and degranulation were studied using intracellular adhesion molecule-1 (ICAM-1)-coated plates, Boyden chamber system, ELISA for eosinophil-derived neurotoxin (EDN) levels in the culture supernatant, respectively. CCR3 expression levels and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation were assessed by flowcytometry. Involvement of PI3K纬 in spontaneous apoptosis was studied using flowcytometry.
Although AS605240 did not affect the eosinophil spontaneous apoptosis, eotaxin-induced chemotaxis, adhesion to ICAM-1 coated plate, and EDN release were inhibited by AS605240. AS605240 also inhibited the eotaxin-induced ERK1/2 phosphorylation without down-regulation of surface CCR3 expression.
These results indicate that PI3K纬 inhibitor attenuates eotaxin-induced eosinophil functions by suppressing the downstream signaling of CCR3 without significant cytotoxicity. PI3K纬 plays an important role in the development of eosinophilic inflammation and blockade of PI3K纬 might be a therapeutic strategy for treatment of eosinophil-related diseases including asthma.