Document Detail


Surfactant protein A modulates cell surface expression of CR3 on alveolar macrophages and enhances CR3-mediated phagocytosis.
MedLine Citation:
PMID:  19155216     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Pulmonary surfactant protein A (SP-A), a member of the collectin family, plays an important role in innate immune defense of the lung. In this study, we examined the role of SP-A in modulating complement receptor-mediated phagocytosis. Complement receptors (CR), CR3 (CD11b), and CR4 (CD11c) were expressed at reduced levels on the surface of alveolar macrophages from Sp-a(-/-) compared with Sp-a(+/+) mice. Administration of intratracheal SP-A to Sp-a(-/-) mice induced the translocation of CR3 from alveolar macrophage intracellular pools to the cell surface. Intratracheal challenge with Haemophilus influenza enhanced CR3 expression on the surface of alveolar macrophages from Sp-a(-/-) and Sp-a(+/+) mice, but relative expression remained lower in the Sp-a(-/-) mice at all time points post-inoculation. The effects of SP-A on macrophage and neutrophil CR3 redistribution between intracellular and cell surface pools were restricted to cells isolated from the lung. SP-A augmented CR3-mediated phagocytosis in a manner that was attenuated by N-glycanase or collagenase treatment of SP-A, implicating the N-linked sugar and collagen-like domains in that function. The binding of CR3 to SP-A was calcium dependent and mediated by the I-domain of CR3 and to a lesser extent by the CR3 lectin domain. Mapping of the domains of SP-A that were required for optimal binding to CR3 revealed that the N-linked sugars were more critical than the collagen-like domain or the extent of oligomeric assembly. We conclude that SP-A modulates the cell surface expression of CR3 on alveolar macrophages, binds to CR3, and enhances CR3-mediated phagocytosis.
Authors:
Malgorzata Gil; Francis X McCormack; Ann Marie Levine
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-01-20
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  284     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2009 Mar 
Date Detail:
Created Date:  2009-03-16     Completed Date:  2009-05-14     Revised Date:  2010-09-23    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  7495-504     Citation Subset:  IM    
Affiliation:
Department of Pediatrics, Division of Critical Care Medicine, University of Florida, Gainesville, Florida 32610, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
CHO Cells
Calcium / metabolism
Cricetinae
Cricetulus
Gene Expression Regulation*
Haemophilus Infections / genetics,  metabolism*
Haemophilus influenzae*
Integrin alphaXbeta2 / genetics,  metabolism
Macrophage-1 Antigen / genetics,  metabolism*
Macrophages, Alveolar / metabolism*
Mice
Mice, Knockout
Neutrophils / metabolism
Peptide Mapping
Phagocytosis*
Protein Binding / genetics
Protein Structure, Tertiary / genetics
Pulmonary Surfactant-Associated Protein A / genetics,  metabolism*
Grant Support
ID/Acronym/Agency:
HL071522/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Integrin alphaXbeta2; 0/Macrophage-1 Antigen; 0/Pulmonary Surfactant-Associated Protein A; 7440-70-2/Calcium
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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