Disparate effects of two phosphatidylcholine binding proteins, C-reactive protein and surfactant protein A, on pulmonary surfactant structure and function.
C-reactive protein (CRP) and surfactant protein A (SP-A) are phosphatidylcholine (PC) binding proteins that function in the innate host defense system. We examined the effects of CRP and SP-A on the surface activity of bovine lipid extract surfactant (BLES), a clinically applied modified natural surfactant. CRP inhibited BLES adsorption to form a surface-active film and the film's ability to lower surface tension (gamma) to low values near 0 mN/m during surface area reduction. The inhibitory effects of CRP were reversed by phosphorylcholine, a water-soluble CRP ligand. SP-A enhanced BLES adsorption and its ability to lower gamma to low values. Small amounts of SP-A blocked the inhibitory effects of CRP. Electron microscopy showed CRP has little effect on the lipid structure of BLES. SP-A altered BLES multilamellar vesicular structure by generating large, loose bilayer structures that were separated by a fuzzy amorphous material, likely SP-A. These studies indicate that although SP-A and CRP both bind PC, there is a difference in the manner in which they interact with surface films.
Nag
Kaushik
K
Department of Chemistry, Canadian Institutes of Health Research Group in Fetal and Neonatal Health and Development, University of Western Ontario, London, Ontario, Canada N6A 5A5.
Rodriguez-Capote
Karina
K
Panda
Amiya Kumar
AK
Frederick
Laura
L
Hearn
Stephen A
SA
Petersen
Nils O
NO
Schürch
Samuel
S
Possmayer
Fred
F
D000327:Adsorption; D000818:Animals; D002097:C-Reactive Protein / Q000494:pharmacology*; D002417:Cattle; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D037662:Pulmonary Surfactant-Associated Protein A / Q000494:pharmacology*; D011663:Pulmonary Surfactants / Q000378:metabolism*
D037662:Pulmonary Surfactant-Associated Protein A; D011663:Pulmonary Surfactants; D002097:C-Reactive Protein