title: Granulocyte-macrophage colony-stimulating factor regulates the functional adhesive state of very late antigen-4 expressed by eosinophils.
abstract: As very late antigen-4 (VLA-4) can exist in different functional states, we have sought to determine whether a cytokine expressed by inflamed endothelium (i.e., granulocyte-macrophage CSF (GM-CSF)) could regulate the functional state of VLA-4 expressed by eosinophils. Using a micropipette single cell adhesion assay able to measure the strength of adhesion forces, eosinophils exhibited low levels of basal adhesion to unstimulated endothelium (separation force, 0.022 +/- 0.003 mdynes). In contrast, individual eosinophils bound to IL-1beta-stimulated endothelium (0.49 +/- 0.02 mdynes), TNF-stimulated endothelium (0.62 +/- 0.05 mdynes), or IL-4-stimulated endothelium (0.11 +/- 0.01 mdynes) with increased avidity as assessed by separation force. Eosinophil binding to IL-4-stimulated endothelium was significantly inhibited by neutralizing Abs to either vascular cell adhesion molecule (VCAM) or VLA-4. The strength of eosinophil adhesion to VCAM (0.31 +/- 0.02 mdynes) or to connecting segment-1 (CS-1) (0.18 mdynes) was greater than the strength of eosinophil adhesion to unstimulated endothelium (0.02 mdynes), but was less than the strength of eosinophil adhesion to IL-1beta-stimulated endothelium (0.49 +/- 0.02 mdynes). After incubating eosinophils for 30 min with GM-CSF, the mean adhesion strength of eosinophils to CS-1 and VCAM increased significantly by 84 and 54%, respectively, compared with that of controls. This increased binding of eosinophils to VCAM or CS-1 was not due to alterations in VLA-4 receptor number (assessed by FACS analysis) or alterations in VLA-4 receptor distribution (assessed by confocal microscopy). These studies suggest that endothelial-derived cytokines such as GM-CSF have the potential to alter the functional state of eosinophil-expressed VLA-4 from a low affinity state to a high affinity state.
authors.affiliation: Department of Orthopedics and Bioengineering, University of California, San Diego 92037, USA.
authors.forename: K L
authors.initials: KL
authors.lastname: Sung
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Elices
authors.forename: J
authors.initials: J
authors.lastname: Gang
authors.forename: P
authors.initials: P
authors.lastname: Sriramarao
authors.forename: D H
authors.initials: DH
authors.lastname: Broide
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D004730:Endothelium, Vascular / Q000378:metabolism; D004804:Eosinophils / Q000187:drug effects* / Q000378:metabolism*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D039041:Integrin alpha4beta1; D016023:Integrins / Q000096:biosynthesis* / Q000187:drug effects*; D009842:Oligopeptides / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D016201:Receptors, Lymphocyte Homing / Q000096:biosynthesis* / Q000187:drug effects*; D016029:Receptors, Very Late Antigen / Q000187:drug effects / Q000502:physiology*; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D039041:Integrin alpha4beta1; D016023:Integrins; D009842:Oligopeptides; D016201:Receptors, Lymphocyte Homing; D016029:Receptors, Very Late Antigen; D019010:Vascular Cell Adhesion Molecule-1; C094697:glutamyl-isoleucyl-leucyl-aspartyl-valine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor