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.
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.
Kaushik
K
Nag
Karina
K
Rodriguez-Capote
Amiya Kumar
AK
Panda
Laura
L
Frederick
Stephen A
SA
Hearn
Nils O
NO
Petersen
Samuel
S
Schürch
Fred
F
Possmayer
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