title: Urokinase receptor is necessary for adequate host defense against pneumococcal pneumonia.
abstract: Cell recruitment is a multistep process regulated by cytokines, chemokines, and growth factors. Previous work has indicated that the urokinase plasminogen activator receptor (uPAR) may also play a role in this mechanism, presumably by an interaction with the beta(2) integrin CD11b/CD18. Indeed, an essential role of uPAR in neutrophil recruitment during pulmonary infection has been demonstrated for beta(2) integrin-dependent respiratory pathogens. We investigated the role of uPAR and urokinase plasminogen activator (uPA) during pneumonia caused by a beta(2) integrin-independent respiratory pathogen, Streptococcus pneumoniae. uPAR-deficient (uPAR(-/-)), uPA-deficient (uPA(-/-)), and wild-type (Wt) mice were intranasally inoculated with 10(5) CFU S. pneumoniae. uPAR(-/-) mice showed reduced granulocyte accumulation in alveoli and lungs when compared with Wt mice, which was associated with more S. pneumoniae CFU in lungs, enhanced dissemination of the infection, and a reduced survival. In contrast, uPA(-/-) mice showed enhanced host defense, with more neutrophil influx and less pneumococci in the lungs compared with Wt mice. These data suggest that uPAR is necessary for adequate recruitment of neutrophils into the alveoli and lungs during pneumonia caused by S. pneumoniae, a pathogen eliciting a beta(2) integrin-independent inflammatory response. This function is even more pronounced when uPAR is unoccupied by uPA.
authors.affiliation: Department of Experimental Internal Medicine, University of Amsterdam, Amsterdam, The Netherlands. a.w.rijneveld@amc.uva.nl
authors.forename: Anita W
authors.initials: AW
authors.lastname: Rijneveld
authors.forename: Marcel
authors.initials: M
authors.lastname: Levi
authors.forename: Sandrine
authors.initials: S
authors.lastname: Florquin
authors.forename: Peter
authors.initials: P
authors.lastname: Speelman
authors.forename: Peter
authors.initials: P
authors.lastname: Carmeliet
authors.forename: Tom
authors.initials: T
authors.lastname: van Der Poll
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D002465:Cell Movement / Q000235:genetics / Q000276:immunology; D018925:Chemokines / Q000096:biosynthesis; D015169:Colony Count, Microbial; D016207:Cytokines / Q000096:biosynthesis; D008168:Lung / Q000201:enzymology / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011018:Pneumonia, Pneumococcal / Q000276:immunology* / Q000382:microbiology / Q000401:mortality / Q000473:pathology; D011956:Receptors, Cell Surface / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D055293:Receptors, Urokinase Plasminogen Activator; D013296:Streptococcus pneumoniae / Q000254:growth & development; D016019:Survival Analysis; D014568:Urokinase-Type Plasminogen Activator / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: D018925:Chemokines; D016207:Cytokines; C524899:Plaur protein, mouse; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator