title: The roles of adhesion molecules and proteinases in lymphocyte transendothelial migration.
abstract: T cell extravasation into perivascular tissue during inflammation involves transmigration through the endothelial cell (EC) layer and basement membrane. We have demonstrated that matrix metalloxproteinase-2 (MMP-2) is induced in T cells upon adhesion to endothelial cells and that the induction of MMP-2 is mediated by binding of T cell VLA-4 to VCAM-1. Cloned murine Th1 cells antigenic to myelin basic protein, either expressing VLA-4 on their cell surface and causing experimental autoimmune encephalomyelitis (EAE) or not expressing VLA-4 and not causing EAE, were used. VLA-4 positive (+) T cells that adhered to VCAM-1 positive (+) endothelial cells exhibited an induction in MMP-2 mRNA, protein, and activity, whereas MMP-2 was not induced in the T cells that adhered to the VCAM-1 negative (-) endothelial cells or VLA-4 negative (-) T cells that adhered to VCAM-1+ endothelial cells. Incubating T cells with rVCAM-1-coated dishes showed that VLA-4+ T cells adhered to the molecule and that adhesion to rVCAM-1 was sufficient to induce MMP-2. VLA-4+ T cells that had transmigrated through a VCAM-1+ endothelial cell monolayer exhibited MMP-2 activity. TIMP-2 was shown to reduce T cell transmigration in vitro. Transmigrated T cells exhibited downregulation of VLA-4 and LFA-1 integrin surface expression and decreased binding to rVCAM-1 and rICAM-1 and increased binding to collagens I and IV, fibronectin, and laminin. Brain sections of mice demonstrated that as T cells migrated farther into the tissue, VLA-4 expression was lost, although CD4 expression remained unchanged. These results demonstrate that binding to VCAM-1 on endothelial cells induces MMP-2 in T cells, which, in turn, may facilitate T cell migration into perivascular tissue. The significance of these findings in the modulation of the inflammatory response is discussed.
authors.affiliation: Department of Pathology, Yale University, New Haven, CT 06510, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Madri
authors.forename: D
authors.initials: D
authors.lastname: Graesser
authors.forename: T
authors.initials: T
authors.lastname: Haas
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000502:physiology*; D002465:Cell Movement; D004727:Endothelium / Q000473:pathology; D018093:Gelatinases / Q000502:physiology*; D006801:Humans; D007249:Inflammation / Q000473:pathology; D039041:Integrin alpha4beta1; D016023:Integrins / Q000502:physiology; D020778:Matrix Metalloproteinase 2; D008666:Metalloendopeptidases / Q000502:physiology*; D016201:Receptors, Lymphocyte Homing / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*; D019010:Vascular Cell Adhesion Molecule-1 / Q000502:physiology
chemical_list: D015815:Cell Adhesion Molecules; D039041:Integrin alpha4beta1; D016023:Integrins; D016201:Receptors, Lymphocyte Homing; D019010:Vascular Cell Adhesion Molecule-1; D018093:Gelatinases; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2