Interactions of pulmonary collectins with Bordetella bronchiseptica and Bordetella pertussis lipopolysaccharide elucidate the structural basis of their antimicrobial activities.
Surfactant proteins A (SP-A) and D (SP-D) play an important role in the innate immune defenses of the respiratory tract. SP-A binds to the lipid A region of lipopolysaccharide (LPS), and SP-D binds to the core oligosaccharide region. Both proteins induce aggregation, act as opsonins for neutrophils and macrophages, and have direct antimicrobial activity. Bordetella pertussis LPS has a branched core structure and a nonrepeating terminal trisaccharide. Bordetella bronchiseptica LPS has the same structure, but lipid A is palmitoylated and there is a repeating O-antigen polysaccharide. The ability of SP-A and SP-D to agglutinate and permeabilize wild-type and LPS mutants of B. pertussis and B. bronchiseptica was examined. Previously, wild-type B. pertussis was shown to resist the effects of SP-A; however, LPS mutants lacking the terminal trisaccharide were susceptible to SP-A. In this study, SP-A was found to aggregate and permeabilize a B. bronchiseptica mutant lacking the terminal trisaccharide, while wild-type B. bronchiseptica and mutants lacking only the palmitoyl transferase or O antigen were resistant to SP-A. Wild-type B. pertussis and B. bronchiseptica were both resistant to SP-D; however, LPS mutants of either strain lacking the terminal trisaccharide were aggregated and permeabilized by SP-D. We conclude that the terminal trisaccharide protects Bordetella species from the bactericidal functions of SP-A and SP-D. The O antigen and palmitoylated lipid A of B. bronchiseptica play no role in this resistance.
Schaeffer
Lyndsay M
LM
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, 231 Albert Sabin Way, ML 0524, Cincinnati, OH 45267, USA.
McCormack
Francis X
FX
Wu
Huixing
H
Weiss
Alison A
AA
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016950:Bordetella bronchiseptica / Q000187:drug effects / Q000472:pathogenicity*; D001886:Bordetella pertussis / Q000187:drug effects / Q000472:pathogenicity*; D002463:Cell Membrane Permeability / Q000187:drug effects; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000378:metabolism; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000276:immunology; D010587:Phagocytosis / Q000187:drug effects; D037662:Pulmonary Surfactant-Associated Protein A / Q000494:pharmacology*; D037663:Pulmonary Surfactant-Associated Protein D / Q000494:pharmacology*; D051381:Rats
D000900:Anti-Bacterial Agents; D008070:Lipopolysaccharides; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D