title: Transmigration of neutrophils across inflamed endothelium is signaled through LFA-1 and Src family kinase.
abstract: Leukocyte capture on inflamed endothelium is facilitated by a shift in LFA-1 from low to high affinity that supports binding to ICAM-1. LFA-1 bonds help anchor polymorphonuclear leukocytes (PMN) to inflamed endothelium in shear flow, and their redistribution to the leading edge guides pseudopod formation, migration, and extravasation. These events can be disrupted at the plasma membrane by stabilizing LFA-1 in a low- or intermediate-affinity state with allosteric small molecules. We hypothesized that a minimum dimeric bond formation between high-affinity LFA-1 and ICAM-1 under shear stress is necessary to catalyze transmembrane signaling of directed cell migration. Microspheres and substrates were derivatized with monomeric or dimeric ICAM-1 to simulate the surface of inflamed endothelium under defined ligand valence. Binding to dimeric ICAM-1, and not monomeric ICAM-1, was sufficient to elicit assembly of F-actin and phosphorylation of Src family kinases that colocalized with LFA-1 on adherent PMN. Genetic deletion or small molecule inhibition of Src family kinases disrupted their association with LFA-1 that correlated with diminished polarization of arrested PMN and abrogation of transmigration on inflamed endothelium. We conclude that dimeric bond clusters of LFA-1/ICAM-1 provide a key outside-in signal for orienting cytoskeletal dynamics that direct PMN extravasation at sites of inflammation.
authors.affiliation: Department of Biomedical Engineering, University of California, Davis, CA 95616, USA.
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Sarantos
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Ulrich Y
authors.initials: UY
authors.lastname: Schaff
authors.forename: Neha
authors.initials: N
authors.lastname: Dixit
authors.forename: Heather N
authors.initials: HN
authors.lastname: Hayenga
authors.forename: Clifford A
authors.initials: CA
authors.lastname: Lowell
authors.forename: Scott I
authors.initials: SI
authors.lastname: Simon
mesh_terms: D000199:Actins / Q000097:blood / Q000378:metabolism / Q000502:physiology; D000818:Animals; D002448:Cell Adhesion / Q000276:immunology; D002449:Cell Aggregation / Q000276:immunology; D002460:Cell Line; D002465:Cell Movement / Q000276:immunology*; D002478:Cells, Cultured; D019281:Dimerization; D004730:Endothelium, Vascular / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood / Q000378:metabolism / Q000502:physiology; D016169:Lymphocyte Function-Associated Antigen-1 / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation; D011485:Protein Binding / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology*; D019061:src-Family Kinases / Q000378:metabolism / Q000502:physiology*
chemical_list: D000199:Actins; D018836:Inflammation Mediators; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1; D019061:src-Family Kinases