Surfactant protein-A enhances ureaplasmacidal activity in vitro.
BACKGROUND
Persistent respiratory tract colonization with Ureaplasma spp. in preterm infants is a significant risk factor for the development of the chronic lung disorder, bronchopulmonary dysplasia (BPD). Surfactant protein-A (SP-A), a lung collectin critical for bacterial clearance and regulating inflammation, is deficient in the preterm lung. In an experimental Ureaplasma-pneumonia model, infected SP-A deficient mice exhibited delayed bacterial clearance and an exaggerated inflammatory response compared to infected wild-type mice. The objective was to analyze the role of SP-A in Ureaplasma clearance in vitro.


METHODS
We analyzed SP-A binding to Ureaplasma isolates and SP-A-mediated ureaplasmal phagocytosis and killing by cultured RAW 264.7 macrophages.


RESULTS
Calcium-dependent SP-A binding was similar among Ureaplasma isolates tested. Pre-incubation of RAW 264.7 cells with SP-A (10-50 μg/ml) enhanced phagocytosis of fluorescein-isothiocyanate (FITC)-labeled Ureaplasma. Surfactant protein-A also increased ureaplasmacidal activity of RAW 264.7 cells by 2.1-fold over 4 h. Pre-incubation of RAW 264.7 cells with 10 μg/ml SP-A reduced lipopolysaccharide (LPS) (100 ng/ml) and Ureaplasma (10(6) color changing units/ml)-stimulated release of tumor necrosis factor-α (TNF-α) by 46% and 43%, respectively, but did not affect transforming growth factor β(1) (TGFβ(1)) release.


CONCLUSIONS
These in vitro data confirm that SP-A is important in host defense to perinatally-acquired Ureaplasma infection.
Okogbule-Wonodi
Adora C
AC
Department of Pediatrics, School of Medicine, University of Maryland-Baltimore (UMB), 29 S. Greene St., Baltimore, MD 21201, USA.
Chesko
Kirsty L
KL
Famuyide
Mobolaji E
ME
Viscardi
Rose M
RM
D000818:Animals; D002460:Cell Line; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D006801:Humans; D007231:Infant, Newborn; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism / Q000382:microbiology / Q000473:pathology; D051379:Mice; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology; D037662:Pulmonary Surfactant-Associated Protein A / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014509:Ureaplasma / Q000276:immunology* / Q000472:pathogenicity; D016869:Ureaplasma Infections / Q000188:drug therapy* / Q000276:immunology
D037662:Pulmonary Surfactant-Associated Protein A; D014409:Tumor Necrosis Factor-alpha