Surfactant protein A regulates surfactant phospholipid clearance after LPS-induced injury in vivo

Abstract
Previous in vitro studies have suggested that surfactant protein A (SP-A) may play a role in pulmonary surfactant homeostasis by mediating surfactant secretion and clearance. However, mice made deficient in SP-A [SP-A (−/−) animals] have relatively normal levels of surfactant compared with wild-type SP-A (+/+) animals. We hypothesize that SP-A may play a role in surfactant homeostasis after acute lung injury. Bacterial lipopolysaccharide was instilled into the lungs of SP-A (−/−) mice and SP-A (+/+) mice to induce injury. Surfactant phospholipid levels were increased 1.6-fold in injured SP-A (−/−) animals, although injury did not alter [3H]choline or [14C]palmitate incorporation into dipalmitoylphosphatidylcholine (DPPC), suggesting no change in surfactant synthesis/secretion 12 h after injury. Clearance of [3H]DPPC from the lungs of injured SP-A (−/−) animals was decreased by ∼40%. Instillation of 50 μg of exogenous SP-A rescued both the clearance defect and the increased phospholipid defect in injured SP-A (−/−) animals, suggesting that SP-A may play a role in regulating clearance of surfactant phospholipids after acute lung injury.

This publication has 63 references indexed in Scilit: