title: Surfactant-associated protein A provides critical immunoprotection in neonatal mice.
abstract: The collectins surfactant-associated protein A (SP-A) and SP-D are components of innate immunity that are present before birth. Both proteins bind pathogens and assist in clearing infection. The significance of SP-A and SP-D as components of the neonatal immune system has not been investigated. To determine the role of SP-A and SP-D in neonatal immunity, wild-type, SP-A null, and SP-D null mice were bred in a bacterium-laden environment (corn dust bedding) or in a semisterile environment (cellulose fiber bedding). When reared in the corn dust bedding, SP-A null pups had significant mortality (P < 0.001) compared to both wild-type and SP-D null pups exposed to the same environment. The mortality of the SP-A null pups was associated with significant gastrointestinal tract pathology but little lung pathology. Moribund SP-A null newborn mice exhibited Bacillus sp. and Enterococcus sp. peritonitis. When the mother or newborn produced SP-A, newborn survival was significantly improved (P < 0.05) compared to the results when there was a complete absence of SP-A in both the mother and the pup. Significant sources of SP-A likely to protect a newborn include the neonatal lung and gastrointestinal tract but not the lactating mammary tissue of the mother. Furthermore, exogenous SP-A delivered by mouth to newborn SP-A null pups with SP-A null mothers improved newborn survival in the corn dust environment. Therefore, a lack of SP-D did not affect newborn survival, while SP-A produced by either the mother or the pup or oral exogenous SP-A significantly reduced newborn mortality associated with environmentally induced infection in SP-A null newborns.
authors.affiliation: Department of Pediatrics, University of Iowa, Carver College of Medicine, Iowa City, Iowa 52242, USA. cgeorge@umn.edu
authors.forename: Caroline L S
authors.initials: CL
authors.lastname: George
authors.forename: Kelli L
authors.initials: KL
authors.lastname: Goss
authors.forename: David K
authors.initials: DK
authors.lastname: Meyerholz
authors.forename: Fred S
authors.initials: FS
authors.lastname: Lamb
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Snyder
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000276:immunology*; D001512:Bedding and Linens; D004391:Dust; D005260:Female; D017353:Gene Deletion; D015870:Gene Expression; D006801:Humans; D007112:Immunity, Maternally-Acquired; D008098:Litter Size; D008297:Male; D051379:Mice; D037662:Pulmonary Surfactant-Associated Protein A / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D037663:Pulmonary Surfactant-Associated Protein D; D003313:Zea mays
chemical_list: D004391:Dust; D037662:Pulmonary Surfactant-Associated Protein A; D037663:Pulmonary Surfactant-Associated Protein D