The effect of pharmacological PI3Kγ inhibitor on eotaxin-induced human eosinophil functions

• Published in: Pulmonary pharmacology & therapeutics 2014-04, Vol.27 (2), p.164-169
• Main Authors: Saito, Yukiko, Takeda, Masahide, Nishikawa, Junko, Konno, Yasunori, Tamaki, Mami, Itoga, Masamichi, Kobayashi, Yoshiki, Moritoki, Yuki, Ito, Wataru, Chihara, Junichi, Ueki, Shigeharu
• Format: Article
• Language: English
• Subjects: Asthma; Chemokine CCL11 - metabolism; Chemotaxis - drug effects; Class Ib Phosphatidylinositol 3-Kinase - antagonists & inhibitors; Class Ib Phosphatidylinositol 3-Kinase - metabolism; Down-Regulation - drug effects; Enzyme-Linked Immunosorbent Assay; Eosinophil; Eosinophil-Derived Neurotoxin - metabolism; Eosinophils - drug effects; Eosinophils - metabolism; Eotaxin; Flow Cytometry; Humans; Medical Education; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - metabolism; Phosphorylation; PI3Kγ; Pulmonary/Respiratory; Quinoxalines - pharmacology; Thiazolidinediones - pharmacology
• ISSN: 1094-5539; 1522-9629
• DOI: 10.1016/j.pupt.2013.11.006

Abstract Background Asthma is characterized by chronic inflammation caused by activation of immune cells including Th2 lymphocytes and eosinophils. Phosphoinositide 3-kinase (PI3K) γ deficient asthmatic mice did not develop lung eosinophilia, although the detailed mechanisms are not well known. A CC chemokine eotaxin (CCL11) plays a prominent role in developing eosinophilic inflammation through CCR3. In this study, we tested the roles of PI3Kγ in eotaxin-induced eosinophil functions using a pharmacological inhibitor. Method Human peripheral blood eosinophils were isolated by CD16-negative selection method. The effect of AS605240, synthetic PI3Kγ 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 PI3Kγ in spontaneous apoptosis was studied using flowcytometry. Results 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. Conclusion These results indicate that PI3Kγ inhibitor attenuates eotaxin-induced eosinophil functions by suppressing the downstream signaling of CCR3 without significant cytotoxicity. PI3Kγ plays an important role in the development of eosinophilic inflammation and blockade of PI3Kγ might be a therapeutic strategy for treatment of eosinophil-related diseases including asthma.