Neutrophil tethering on E-selectin activates beta 2 integrin binding to ICAM-1 through a mitogen-activated protein kinase signal transduction pathway.
On inflamed endothelium selectins support neutrophil capture and rolling that leads to firm adhesion through the activation and binding of beta 2 integrin. The primary mechanism of cell activation involves ligation of chemotactic agonists presented 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 via beta 2integrins. Neutrophils were introduced into a parallel plate flow chamber having as a substrate an L cell monolayer coexpressing E-selectin and ICAM-1 (E/I). At shears >/=0.1 dyne/cm2, neutrophils rolled on the E/I. A step increase to 4.0 dynes/cm2 revealed that approximately 60% of the interacting cells remained firmly adherent, as compared with approximately 10% on L cells expressing E-selectin or ICAM-1 alone. Cell arrest was dependent on application of shear and activation of Mac-1 and LFA-1 to bind ICAM-1. Firm adhesion was inhibited by blocking E-selectin, L-selectin, or PSGL-1 with Abs and by inhibitors to the mitogen-activated protein kinases. A chimeric soluble E-selectin-IgG molecule specifically bound sialylated ligands on neutrophils and activated adhesion that was also inhibited by blocking the mitogen-activated protein kinases. We conclude that neutrophils rolling on E-selectin undergo signal transduction leading to activation of cell arrest through beta 2 integrins binding to ICAM-1.
Simon
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Speros Martel Section of Leukocyte Biology, Baylor College of Medicine, Houston, TX 77030, USA. sisimon@ucdavis.edu
Hu
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Vestweber
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Smith
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D000328:Adult; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D018821:CD18 Antigens / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D002634:Chemotaxis, Leukocyte / Q000502:physiology; D019040:E-Selectin / Q000096:biosynthesis / Q000502:physiology*; D018056:Hemorheology / Q000379:methods; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000378:metabolism*; D007739:L Cells; D008024:Ligands; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D018375:Neutrophil Activation / Q000502:physiology; D009504:Neutrophils / Q000201:enzymology* / Q000502:physiology*; D011485:Protein Binding / Q000502:physiology
D018821:CD18 Antigens; D019040:E-Selectin; D008024:Ligands; D018799:Intercellular Adhesion Molecule-1