Mechanico-transduction through selectins signals integrin mediated neutrophil arrest under shear flow

摘要

On inflamed endothelium selectins support neutrophil capture and rolling that leads to firm adhesion through the activation and binding of β{sub}2-integrin. The primary mechanism of cell activation involves ligation of chemotactic agonistspresented on the endothelium. We have pursued a second mechanism involving signal transduction through binding of selectins while neutrophils tether in shear flow. We assessed whether neutrophil rolling on E-selectin led to cell activation and arrest viaβ{sub}2-integrins. Neutrophils were introduced into a parallel plate flow chamber having as a substrate an L cell monolayer co-expressing E-selectin and ICAM-1 (E/I). At shears ≤5 dyn/cm{sup}2 neutrophils rolled on the E/I. A step increase to 4.0dyn/cm{sup}2 revealed that ～60% remained firmly adherent, as compared to ～10% on L cells expressing E-selectin or ICAM-1 alone. Cell arrest was dependent on application of shear and activation of β{sub}2-integrins to bind ICAM-1. The transition fromneutrophil rolling to arrest was inhibited by blocking E-selectin, L-selectin, PSGL-1 with antibodies and by antagonists to the MAP kinases. A chimeric soluble E-selectin-IgG molecule also activated adhesive function in cell suspension that was inhibitedwith antagonists to MAP kinases. We conclude that neutrophils Tolling on E-selectin undergo signal transduction leading to activation of cell arrest through β{sub}2-integrin binding to ICAM-1.