Interaction of bacterial lipopolysaccharide with mouse surfactant protein C inserted into lipid vesicles.
Infection of the respiratory tract is a frequent cause of lung pathologies, morbidity, and death. When bacterial endotoxin [lipopolysaccharide (LPS)] reaches the alveolar spaces, it encounters the lipid-rich surfactant that covers the epithelium. Although binding of hydrophilic surfactant protein (SP) A and SP-D with LPS has been established, nothing has been reported to date on possible cross talks between LPS and hydrophobic SP-B and SP-C. We designed a new binding technique based on the incorporation of surfactant components to lipid vesicles and the separation of unbound from vesicle-bound LPS on a density gradient. We found that among the different hydrophobic components of mouse surfactant separated by gel filtration or reverse-phase HPLC, only SP-C exhibited the capacity to bind to a tritium-labeled LPS. The binding of LPS to vesicles containing SP-C was saturable, temperature dependent, related to the concentrations of SP-C and LPS, and inhibitable by distinct unlabeled LPSs. Unlike SP-A and SP-D, the binding of SP-C to LPS did not require calcium ions. This LPS binding capacity of SP-C may represent another antibacterial defense mechanism of the lung.
Augusto
L
L
Endotoxin Group, Unité Mixte de Recherche-8619 of the National Center for Scientific Research, University of Paris-Sud, 91405 Orsay, France.
Le Blay
K
K
Auger
G
G
Blanot
D
D
Chaby
R
R
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006023:Glycoproteins / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism* / Q000494:pharmacology; D008168:Lung / Q000378:metabolism; D051379:Mice; D019308:Palmitic Acid / Q000378:metabolism; D011510:Proteolipids / Q000378:metabolism*; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D013499:Surface Properties / Q000187:drug effects; D022161:Transport Vesicles / Q000378:metabolism*; D014316:Tritium
D006023:Glycoproteins; D008070:Lipopolysaccharides; D011510:Proteolipids; D037663:Pulmonary Surfactant-Associated Protein D; D011663:Pulmonary Surfactants; D014316:Tritium; D019308:Palmitic Acid