β2-integrins and acquired glycoprotein IIb/IIIa (GPIIb/IIIa) receptors cooperate in NF-κB activation of human neutrophils

Microparticles from various cells are generated during inflammation. Platelet-derived microparticles (PMPs) harbor receptors that are not genuinely expressed by neutrophils. We tested whether or not functional glycoprotein IIb/IIIa (GPIIb/ IIIa) receptors can be acquired by neutrophils via PMPs and whether these receptors participate in pro-inflammatory signaling. Surface expression was analyzed by flow cytometry and confocal microscopy. NF-kappa B activation was analyzed by Western blot experiments, electrophoretic mobility shift assays, and reverse transcription-PCR. Cell adhesion and spreading were estimated by myeloperoxidase assay and light microscopy. We found that PMPs transfer GPIIb/IIIa receptors to isolated and whole blood neutrophils via PMPs. We used specific antibodies in granulocyte macrophage colony-stimulating factor-treated neutrophils and observed that acquired GPIlb/Illa receptors colocalized with beta 2-integrins and cooperated in NF-kappa B activation. We show that Src and Syk non-receptor tyrosine kinases, as well as the actin cytoskeleton, control NF-kappa B activation. In contrast to NF-kappa B, acquisition of GPIIb/IIIa receptors was not necessary to induce adhesion to fibronectin or phosphatidylinositol 3-kinase/Akt signaling. When granulocyte macrophage colony-stimulating factor-stimulated neutrophils were incubated on fibronectin, strong NF-kappa B activation was observed, but only after loading with PMPs. Blocking either beta 2-integrins or GPIIb/ IIIa receptors abrogated this effect. Therapeutic GPIIb/IIIa inhibitors were similarly effective. The compounds also inhibited NF-kappa B-dependent tumor necrosis factor-alpha mRNA up-regulation. The data implicate GPIIb/IIIa receptors as new therapeutic targets in neutrophil-induced inflammation.