Activation of phosphatidylinositol 3-kinase/protein kinase B induced by trypsin in neutrophils

Objective:To investigate whether phosphatidylinositol 3-kinase/protein kinase B (PI3K/PKB) signal transduction pathway could be activated rapidly by trypsin in neutrophils and whether LY294002 and wortmannin,PI3K inhibitors,could inhibit such effect of trypsin. Methods:The levels of phosphorylated PKB (p-PKB) and total PKB were examined by Western blotting in neutrophils after stimulation with 40 nmol/L of trypsin. The inhibitory effects of LY294002 and wortmannin on the activation of PKB induced by trypsin were observed. The levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) protein and mRNA in the culture and neutrophils were determined by enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction,respectively. Results:The level of p-PKB in neutrophils and the levels of TNF-α and IL-1β protein in the culture after stimulation with trypsin were significantly higher than those in normal controls (P 0.01). Wortmannin and LY294002 could completely inhibit the activation of p-PKB induced by trypsin in neutrophils. With the inhibition of p-PKB,the levels of TNF-α and IL-1β protein and mRNA decreased. Conclusion:Trypsin could activate PI3K/PKB signal transduction pathway in neutrophils,and this action of trypsin is PI3K-dependent and could be inhibited or blocked by wortmannin and LY294002.