Effective attenuation of acute lung injury in vivo and the formyl peptide-induced neutrophil activation in vitro by CYL-26z through the phosphoinositide 3-kinase γ pathway

5-[4-Acridin-9-ylaminolphenyl]-5-methyl-3-methylenedihydrofuran-2-one (CYL-26z) inhibited the polymorphonuclear leukocyte (PMNL) infiltration and protein leakage into the lungs in lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice as determined on the basis of PMNL and protein contents in bronchoalveolar lavage (BAL) fluid and myeloperoxidase (MPO) content in whole lung extracts. CYL-26z also attenuated the for-myl-Met-Leu-Phe (fMLP) -induced neutrophil chemotaxis and respiratory burst in vitro (IC50 8.4 +/- 0.9 mu M and 2.0 +/- 0.6 mu M, respectively). CYL-26z had no effect on superoxide anion (O-2(.-)) generation during dihydroxyfumaric acid autoxidation or on the NADPH oxidase activity in two cell-free systems (the arachidonic acid-induced assembly of NADPH oxidase and the preassembled oxidase caused by phorbol ester treatment), whereas it inhibited NaF-induced respiratory burst. inhibition of respiratory burst by CYL-26z was readily reversible by washing. only slight, but significant, inhibition of extracellular signal regulated kinase (ERK) phosphorylation and p38 mitogen-activated protein kinase (MAPK) activation in response to fMLP by CYL-26z up to 30 mu M was obtained. CYL-26z effectively blocked the formation of phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P-3) as determined by immunofluorescence microscopy and flow cytometry assays and the dual phosphorylation of protein kinase B (PKB/Akt) on S473 and T308 residues in fMLP-stimulated neutrophils. The membrane recruitment of p110 gamma and Ras, the Ras activation, and the association between p110 gamma and Ras were also attenuated by CYL-26z. These results indicate that the blockade of Ras activation by CYL-26z attenuated the downstream phosphoinositide 3-kinase (PI3K)gamma signaling, which is involved in chemoattractant-induced neutrophil chemotaxis and respiratory burst, and may have a beneficial anti-inflammatory effect on ALI. (c) 2006 Elsevier Inc. All rights reserved.