Beta2-integrins and acquired glycoprotein IIb/IIIa (GPIIb/IIIa) receptors cooperate in NF-kappaB 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 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-kappaB activation was analyzed by western blot experiments, electrophoretic mobility shift assays, and RT-PCR. Cell adhesion and spreading was 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 GM-CSF-treated neutrophils and observed that acquired GPIIb/IIIa receptors co-localized with beta2-integrins and cooperated in NF-kappaB activation. We show that Src and Syk non-receptor tyrosine kinases, as well as the actin cytoskeleton, control NF-kappaB activation. In contrast to NF-kappaB, acquisition of GPIIb/IIIa receptors was not necessary to induce adhesion to fibronectin or PI3K/Akt signaling. When GM-CSF-stimulated neutrophils were incubated on fibronectin, strong NF-kappaB activation was observed, but only after loading with PMPs. Blocking either beta2-integrins or GPIIb/IIIa receptors abrogated this effect. Therapeutic GPIIb/IIIa inhibitors were similarly effective. The compounds also inhibited NF-kappaB-dependent TNF-alpha mRNA up-regulation. The data implicate GPIIb/IIIa receptors as new therapeutic targets in neutrophil-induced inflammation.