INHIBITION OF KINASES IMPAIRS NEUTROPHIL ACTIVATION AND KILLING OF STAPHYLOCOCCUS-AUREUS

Intracellular phosphorylations polymorphonuclear neutrophils are media ted by kinases, including mitogen activated-protein (MAP) kinases and phosphatidylinositol 3-kinase. In the present study we demonstrate the ir effector functions upon both ligation of cell-surface seven-transme mbrane-spanning receptors by bacterial peptide formylmethionyl-leucylp henylalanine as well as in the process of destruction of Staphylococcu s aureus. To regulate neutrophil MAP kinases p38 and p44/42, specifica lly, we made use of their specific inhibitors 10 mu M SK&F 86002 (for p38) and PD 098059 (for activating kinase of p44/42). SK&F 86002 was a potent inhibitor (by 70%) of induced antimicrobial oxygen-radical gen eration compared with PD 098059 (by 20%). SK&F 86002 and PD 098059 inh ibited mobilization of a dominant neutrophil adhesion molecule, beta(2 ) integrin, from cytoplasmic granules to the plasma membrane by 40 and 10% respectively, and the combination of the two drugs resulted in a 90%, effect. The combined effect of both drugs was moderate inhibition of bacterial destruction, despite the fact that neither compound had detectable effect on bactericidal activity if applied individually. Ba cterial destruction was also inhibited by wortmannin (0.1 mu M), the s pecific inhibitor of phosphatidylinositol 3-kinase, which had previous ly been described to target various other activations of the neutrophi l, including oxygen-radical generation. Although the relative contribu tion of p38 and p44/42 MAP kinases varied, the marked effects of the c ombined inhibition of the kinases revealed their concerted actions to be critical for normal neutrophil function.