Dynamic shifts in LFA-1 affinity regulate neutrophil rolling, arrest, and transmigration on inflamed endothelium.
Polymorphonuclear leukocyte (PMN) recruitment to vascular endothelium during acute inflammation involves cooperation between selectins, G-proteins, and beta2-integrins. LFA-1 (CD11a/CD18) affinity correlates with specific adhesion functions because a shift from low to intermediate affinity supports rolling on ICAM-1, whereas high affinity is associated with shear-resistant leukocyte arrest. We imaged PMN adhesion on cytokine-inflamed endothelium in a parallel-plate flow chamber to define the dynamics of beta2-integrin function during recruitment and transmigration. After arrest on inflamed endothelium, high-affinity LFA-1 aligned along the uropod-pseudopod major axis, which was essential for efficient neutrophil polarization and subsequent transmigration. An allosteric small molecule inhibitor targeted to the I-domain stabilized LFA-1 in an intermediate-affinity conformation, which supported neutrophil rolling but inhibited cell polarization and abrogated transmigration. We conclude that a shift in LFA-1 from intermediate to high affinity during the transition from rolling to arrest provides the contact-mediated signaling and guidance necessary for PMN transmigration on inflamed endothelium.
Green
Chad E
CE
Department of Biomedical Engineering, Genome and Biomedical Sciences Facility, University of California at Davis, 451 E Health Sciences Dr, Davis, CA 95616-5294, USA.
Schaff
Ulrich Y
UY
Sarantos
Melissa R
MR
Lum
Aaron F H
AF
Staunton
Donald E
DE
Simon
Scott I
SI
D002448:Cell Adhesion; D002478:Cells, Cultured; D018920:Coculture Techniques; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D036904:Leukocyte Rolling; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D018613:Microscopy, Confocal; D009504:Neutrophils / Q000378:metabolism* / Q000473:pathology; D011554:Pseudopodia / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction
D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1