title: Sequential regulation of alpha 4 beta 1 and alpha 5 beta 1 integrin avidity by CC chemokines in monocytes: implications for transendothelial chemotaxis.
abstract: Leukocyte emigration possibly requires dynamic regulation of integrin adhesiveness for endothelial and extracellular matrix ligands. Adhesion assays on purified vascular cell adhension molecule (VCAM)-1, fibronectin, and fibronectin fragments revealed distinct kinetic patterns for the regulation of very late antigen (VLA)-4 (alpha 4 beta 1) and VLA-5 (alpha 5 beta 1) avidity by the CC chemokines monocyte inflammatory protein (MIP)-1 alpha, RANTES (regulated on activation, normal T expressed and secreted), or monocyte chemoattractant protein (MCP)-1 in monocytes. CC chemokines induced early activation and subsequent deactivation of VLA-4, whereas upregulation of VLA-5 avidity occurred later and persisted. Controlled detachment assays in shear flow suggested that adhesive strength of VLA-4 for VCAM-1 or the 40-kD fragment of fibronectin (FN40) is more rapidly increased and subsequently reduced by MCP-1 than by MIP-1 alpha, and confirmed late and sustained activation of the adhesive strength of VLA-5 for the 120-kD fragment of fibronectin (FN120). Mn2+ or the stimulating beta 1 mAb TS2/16 strongly and stably enhanced monocyte binding to VCAM-1 or fibronectin, and locked beta 1 integrins in a high avidity state, which was not further modulated by CC chemokines. Mn2+ and mAb TS2/16 inhibited CC chemokine-induced transendothelial migration, particularly chemotaxis across stimulated endothelium that involved VLA-4 and VCAM-1. VLA-4 on Jurkat cells is of constitutively high avidity and interfered with migration across barriers expressing VCAM-1. Low but not high site densities of VCAM-1 or FN40 promoted, while FN120 impaired, beta 1 integrin-dependent monocyte chemotaxis to MCP-1 across filters coated with these substrates. Thus, we show that CC chemokines can differentially and selectively regulate avidity of integrins sharing common beta subunits. Transient activation and deactivation of VLA-4 may serve to facilitate transendothelial diapedesis, whereas late and prolonged activation of VLA-5 may mediate subsequent interactions with the basement membrane and extracellular matrix.
authors.affiliation: Center for Blood Research, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: C
authors.initials: C
authors.lastname: Weber
authors.forename: R
authors.initials: R
authors.lastname: Alon
authors.forename: B
authors.initials: B
authors.lastname: Moser
authors.forename: T A
authors.initials: TA
authors.lastname: Springer
mesh_terms: D000911:Antibodies, Monoclonal; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D054407:Chemokine CCL4; D018925:Chemokines / Q000494:pharmacology*; D002634:Chemotaxis, Leukocyte / Q000276:immunology*; D004730:Endothelium, Vascular / Q000276:immunology*; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D039041:Integrin alpha4beta1; D019012:Integrin beta1 / Q000276:immunology; D016023:Integrins / Q000276:immunology*; D007700:Kinetics; D019402:Macrophage Inflammatory Proteins; D009000:Monocytes / Q000276:immunology*; D015846:Monokines / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism; D017469:Receptors, Fibronectin / Q000276:immunology*; D016201:Receptors, Lymphocyte Homing / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D014407:Tumor Cells, Cultured; D014471:Umbilical Veins; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D054407:Chemokine CCL4; D018925:Chemokines; D005353:Fibronectins; D039041:Integrin alpha4beta1; D019012:Integrin beta1; D016023:Integrins; D019402:Macrophage Inflammatory Proteins; D015846:Monokines; D010446:Peptide Fragments; D017469:Receptors, Fibronectin; D016201:Receptors, Lymphocyte Homing; D019010:Vascular Cell Adhesion Molecule-1