%0 Journal Article %A J. Reutershan %A M. S. Saprito %A D. Wu %A T. Rückle %A K. Ley %T Phosphoinositide 3-kinase γ required for lipopolysaccharide-induced transepithelial neutrophil trafficking in the lung %D 2010 %R 10.1183/09031936.00085509 %J European Respiratory Journal %P 1137-1147 %V 35 %N 5 %X Phosphoinositide 3-kinase γ(PI3Kγ) is a critical mediator of directional cell movement. Here, we sought to characterise the role of PI3Kγ in mediating the different steps of polymorphonuclear leukocyte (PMN) trafficking in the lung. In a murine model of lipopolysaccharide (LPS)-induced lung injury, PMN migration into the different lung compartments was determined in PI3Kγ gene-deficient (PI3Kγ-/-) and wild-type mice. Bone marrow chimeras were created to characterise the role of PI3Kγ on haematopoietic versus nonhaematopoietic cells. A small-molecule PI3Kγ inhibitor was tested in vitro and in vivo. PMN adhesion to the pulmonary endothelium and transendothelial migration into the lung interstitium was enhanced in PI3Kγ-/- mice. However, transepithelial migration into the alveolar space was reduced in these mice. When irradiated PI3Kγ-/- mice were reconstituted with bone marrow from wild-type mice, migratory activity into the alveolar space was restored partially. A small-molecule PI3Kγ inhibitor reduced chemokine-induced PMN migration in vitro when PMNs or epithelial cells, but not when endothelial cells, were treated. The inhibitor also reduced LPS-induced PMN migration in vivo. We conclude that PI3Kγ is required for transepithelial but not for transendothelial migration in LPS-induced lung injury. Inhibition of PI3Kγ activity may be effective at curbing excessive PMN infiltration in lung injury. %U https://erj.ersjournals.com/content/erj/35/5/1137.full.pdf