Role of epithelial interleukin-8 (IL-8) and neutrophil IL-8 receptor A in Escherichia coli-induced transuroepithelial neutrophil migration

Escherichia coli stimulates neutrophil migration across human uroepithelial cell layers, This study investigated the role of the neutrophil chemokine interleukin-8 (IL-8) in this process, E. coli and IL-la stimulated urinary tract epithelial layers to secrete IL-8 and induced transepithelial neutrophil migration, Anti-IL-8 antibody reduced neutrophil migration across epithelial cell layers, indicating a central role for this chemokine in the migration process, Furthermore, addition of recombinant IL-8 to unstimulated cell layers was sufficient to induce migration, The IL-8 dependence of neutrophil migration was maintained after removal of soluble IL-8 by washing of the cell layers. Flow cytometry analysis with fluorescein isothiocyanate-labelled IL-8 confirmed IL-8's ability to bind to the epithelial cell surface, Indirect immunofluorescence with confocal laser scanning microscopy showed that IL-8 associated with the epithelial cell layers. Prior incubation of neutrophils with antibodies to IL-8 receptor A (IL-8RA) reduced neutrophil migration, Anti-IL-8 RE antibody had no effect on neutrophil migration, These results demonstrate that IL-8 plays a key role in E. coli- or IL-1 alpha-induced transuroepithelial migration and suggest that epithelial cell-produced IL-8 interacts with IL-8RA on the neutrophil surface.