5-[4-Acridin-9-ylamino]phenyl]-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 formyl-
Met-Leu-Phe (fMLP)-induced neutrophil chemotaxis and respiratory burst in vitro (IC(50) 8.4+/-0.9microM and 2.0+/-0.6microM, 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 30microM 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 p110gamma and Ras, the Ras activation, and the association between p110gamma 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.