title: TNF-alpha-induced transendothelial neutrophil migration is IL-8 dependent.
abstract: The early phases of airway inflammation include complex interactions between leukocytes, vascular endothelium, and inflammatory cytokines. Therefore, we examined tumor necrosis factor-alpha (TNF-alpha)-induced neutrophil migration through polycarbonate filters and human umbilical vein endothelial (HUVE) cells cultured as monolayers on these filters. TNF-alpha induced both dose- and time-dependent migration of neutrophils across both barriers. At 10(-11)-10(-9) M TNF-alpha, neutrophil migration across HUVE monolayers was more than twofold greater than that observed across naked filters. Modified checkerboard experiments indicated that neutrophils crossed naked filters as a chemokinetic rather than chemotactic response. Supernatants of TNF-alpha (10(-9) M)-stimulated HUVE monolayers induced threefold greater migration of neutrophils across naked filters than 10(-9) M TNF-alpha itself, suggesting release of soluble chemotactic factor(s). Pretreatment of HUVE monolayers with actinomycin D inhibited both TNF-alpha-induced production of soluble chemotactic factors and transendothelial neutrophil migration by > 90%. Supernatants from TNF-alpha-treated HUVE cells contained significant concentrations of interleukin 8 (IL-8), and coincubation of these supernatants with anti-IL-8 decreased supernatant-induced chemotaxis. Finally, coincubation of TNF-alpha with anti-IL-8 during transmigration experiments nearly completely inhibited the increase in neutrophil migration measured across HUVE monolayers. In contrast, WEB 2086, a platelet-activating factor receptor antagonist, had no effect. Therefore, endothelial cells greatly facilitate TNF-alpha-induced transcellular migration of neutrophils. This facilitation is dependent on TNF-alpha-stimulated production of IL-8. These data further support the active role of vascular endothelium in recruiting leukocytes to sites of inflammation.
authors.affiliation: Department of Internal Medicine, University of Iowa College of Medicine, Iowa City.
authors.forename: S J
authors.initials: SJ
authors.lastname: Smart
authors.forename: T B
authors.initials: TB
authors.lastname: Casale
mesh_terms: D000906:Antibodies / Q000276:immunology; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000494:pharmacology*; D007700:Kinetics; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D012995:Solubility; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000494:pharmacology*; D014471:Umbilical Veins / Q000166:cytology / Q000378:metabolism
chemical_list: D000906:Antibodies; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha