title: A pneumococcal protein that elicits interleukin-8 from pulmonary epithelial cells.
abstract: To understand how neutrophils are recruited to the lung in pneumococcal pneumonia, the ability of pneumococcal components to elicit the chemokine interleukin (IL)-8 from monolayers of cultured human type II cells was assessed. Heat-killed clinical and laboratory strains of Streptococcus pneumoniae and secreted proteins from exponentially growing pneumococci elicited significant quantities of IL-8 from A549 cells. All strains that elicited IL-8 production secreted a protein ( approximately 90 kDa) that comigrated on SDS-PAGE with a C3-binding protein previously identified in S. pneumoniae. As little as 7 pmol of the purified 90-kDa protein readily elicited levels of IL-8 production equivalent to those obtained with 1 U of IL-1alpha. Supernatant proteins and heat-killed cells of an isogenic mutant that failed to produce the C3-binding protein elicited significantly less IL-8 than did supernatant proteins or heat-killed cells of the parent strain. These results implicate the C3-binding protein of S. pneumoniae in a novel pathway of pulmonary inflammation.
authors.affiliation: Divisions of Critical Care Medicine, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA.
authors.forename: M
authors.initials: M
authors.lastname: Madsen
authors.forename: Y
authors.initials: Y
authors.lastname: Lebenthal
authors.forename: Q
authors.initials: Q
authors.lastname: Cheng
authors.forename: B L
authors.initials: BL
authors.lastname: Smith
authors.forename: M K
authors.initials: MK
authors.lastname: Hostetter
mesh_terms: D001426:Bacterial Proteins / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D008168:Lung / Q000378:metabolism*; D008970:Molecular Weight; D011018:Pneumonia, Pneumococcal / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D016209:Interleukin-8