title: Surfactant protein A blocks recognition of Pseudomonas aeruginosa by CKAP4/P63 on airway epithelial cells.
abstract: We used isogenic mutant strains that were deficient or over-expressed capsule to study the function of the alginate exopolysaccharide in the interaction of Pseudomonas aeruginosa with the human airway epithelial cells (AEC) in the presence or absence of surfactant protein A (SP-A). SP-A prevented the invasion of AEC by alginate-producing P. aeruginosa strains because of a direct effect on the AEC. Monoclonal antibodies to CKAP4/P63, the principal SP-A-binding receptor on AEC, or inhibition of its expression using specific siRNA reduced the invasion of both highly encapsulated and poorly encapsulated strains, but not the invasion of the acapsular mutant. Treatment of AEC with SP-A, monoclonal antibodies to CKAP4/P63, or CKAP4/P63-specific siRNA decreased the binding of purified alginate exopolysaccharide to AEC. Alginate binding to AEC reduced SP-A release by these cells. Because the alginate exopolysaccharide is surface-exposed, levels of SP-A may be crucial to modulate the interaction of P. aeruginosa with AEC.
authors.affiliation: Instituto Universitario de Investigaciones en Ciencias de la Salud, Universidad de las Islas Baleares, Palma de Mallorca,  Spain.
authors.forename: Mariette
authors.initials: M
authors.lastname: Barbier
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Martínez-Ramos
authors.forename: Paul
authors.initials: P
authors.lastname: Townsend
authors.forename: Sebastián
authors.initials: S
authors.lastname: Albertí
mesh_terms: D000464:Alginates / Q000737:chemistry; D000911:Antibodies, Monoclonal; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000276:immunology*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000494:pharmacology; D011485:Protein Binding; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D037662:Pulmonary Surfactant-Associated Protein A / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering; D020545:Respiratory Mucosa / Q000166:cytology*
chemical_list: D000464:Alginates; D000911:Antibodies, Monoclonal; C081876:CKAP4 protein, human; D006603:Hexuronic Acids; D008565:Membrane Proteins; D011135:Polysaccharides, Bacterial; D037662:Pulmonary Surfactant-Associated Protein A; D034741:RNA, Small Interfering; C064841:exopolysaccharide, Pseudomonas; D020723:Glucuronic Acid