Enhanced clearance of surfactant protein D during LPS-induced acute inflammation in rat lung.
Pulmonary surfactant participates in the regulation of alveolar compliance and lung host defense. Surfactant homeostasis is regulated through a combination of synthesis, secretion, clearance, recycling, and degradation of surfactant components. The extracellular pool size of surfactant protein (SP) D fluctuates significantly during acute inflammation. We hypothesized that changes in SP-D levels are due, in part, to altered clearance of SP-D. Clearance pathways in rats were assessed with fluorescently labeled SP-D that was instilled into control lungs or lungs that had been treated with lipopolysaccharide (LPS) 16 h earlier. SP-D clearance from lavage into lung tissue was time dependent from 5 min to 1 h and 1.7-fold greater in LPS-treated lungs than in control lungs. Analysis of cells isolated by enzymatic digestion of lung tissue revealed differences in the SP-D-positive cell population between groups. LPS-treated lungs had 28.1-fold more SP-D-positive tissue-associated neutrophils and 193.6-fold greater SP-D association with those neutrophils compared with control lungs. These data suggest that clearance of SP-D into lung tissue is increased during inflammation and that tissue-associated neutrophils significantly contribute to this process.
Herbein
J F
JF
Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Wright
J R
JR
D000208:Acute Disease; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D002452:Cell Count; D006023:Glycoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009504:Neutrophils / Q000378:metabolism; D011014:Pneumonia / Q000139:chemically induced* / Q000378:metabolism* / Q000473:pathology; D011510:Proteolipids / Q000378:metabolism; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013954:Thyroglobulin / Q000378:metabolism
D006023:Glycoproteins; D008070:Lipopolysaccharides; D011510:Proteolipids; D037663:Pulmonary Surfactant-Associated Protein D; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D013954:Thyroglobulin