title: Plasminogen activator inhibitor-1 supports IL-8-mediated neutrophil transendothelial migration by inhibition of the constitutive shedding of endothelial IL-8/heparan sulfate/syndecan-1 complexes.
abstract: The endothelium is the primary barrier to leukocyte recruitment at sites of inflammation. Neutrophil recruitment is directed by transendothelial gradients of IL-8 that, in vivo, are bound to the endothelial cell surface. We have investigated the identity and function of the binding site(s) in an in vitro model of neutrophil transendothelial migration. In endothelial culture supernatants, IL-8 was detected in a trimolecular complex with heparan sulfate and syndecan-1. Constitutive shedding of IL-8 in this form was increased in the presence of a neutralizing Ab to plasminogen activator inhibitor-1 (PAI-1), indicating a role for endothelial plasminogen activator in the shedding of IL-8. Increased shedding of IL-8/heparan sulfate/syndecan-1 complexes was accompanied by inhibition of neutrophil transendothelial migration, and aprotinin, a potent plasmin inhibitor, reversed this inhibition. Platelets, added as an exogenous source of PAI-1, had no effect on shedding of the complexes or neutrophil migration. Our results indicate that IL-8 is immobilized on the endothelial cell surface through binding to syndecan-1 ectodomains, and that plasmin, generated by endothelial plasminogen activator, induces the shedding of this form of IL-8. PAI-1 appears to stabilize the chemoattractant form of IL-8 at the cell surface and may represent a therapeutic target for novel anti-inflammatory strategies.
authors.affiliation: School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, Hampshire, United Kingdom.
authors.forename: Lindsay J
authors.initials: LJ
authors.lastname: Marshall
authors.forename: Lara S P
authors.initials: LS
authors.lastname: Ramdin
authors.forename: Teresa
authors.initials: T
authors.lastname: Brooks
authors.forename: Peter Charlton
authors.initials: PC
authors.lastname: DPhil
authors.forename: Janis K
authors.initials: JK
authors.lastname: Shute
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001792:Blood Platelets / Q000502:physiology; D002460:Cell Line; D002464:Cell Migration Inhibition; D002474:Cell-Free System / Q000737:chemistry; D002634:Chemotaxis, Leukocyte / Q000276:immunology*; D018920:Coculture Techniques; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D005341:Fibrinolysin / Q000502:physiology; D019812:Heparan Sulfate Proteoglycans / Q000032:analysis / Q000378:metabolism; D006497:Heparan Sulfate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology*; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000276:immunology / Q000502:physiology*; D011509:Proteoglycans / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D012995:Solubility; D053668:Syndecan-1; D053667:Syndecans
chemical_list: D000911:Antibodies, Monoclonal; D005341:Fibrinolysin; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; D016209:Interleukin-8; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D017395:Plasminogen Activator Inhibitor 1; D011509:Proteoglycans; D011994:Recombinant Proteins; D053668:Syndecan-1; D053667:Syndecans; C508241:SDC1 protein, human