Changes in surfactant proteins A and B in dogs with acute lung injury induced by open chest wound and seawater immersion

Objective To investigate the changes in surfactant proteins A (SP-A) and B (SP-B) in dogs with acute lung injury (ALI) induced by open chest wound and seawater immersion and their underlying mechanism.Methods Open pneumothorax was made in 16 healthy dogs,which were then randomly divided into 2 groups (8 each):experimental group (ALI was induced by perfusion of 35mg/kg seawater into thoracic cavity) and control group (without seawater perfusion).All dogs were observed for 6 hours.Contents of TNF-α,IL-8,SP-A and SP-B in lung tissue and serum were detected by ELISA before perfusion (0h) and 2,4,6h after perfusion.Bronchoalveolar lavage was performed 6 hours after perfusion,and the SP-A and SP-B in bronchoalveolar lavage fluid (BALF) and lung homogenate were determined by ELISA.Moreover,histopathological changes and SP-B immunohistochemical detection in lung tissues were performed after the animals were sacrificed at the end of experiment.Results After the introduction of seawater into the pleural cavity,the levels of IL-8 and TNF-α in BALF and blood serum (4h and 6h after perfusion) were significantly higher in experimental group than in control group (P0.05).In the experimental group,SP-A and SP-B in BALF and lung homogenate decreased significantly,SP-A (4h and 6h after perfusion) and SP-B (6h after perfusion) in blood serum increased (P0.05),but no significant change was found in control group.SP-B positive typeⅡ alveolar epithelial cells deereased in number in lung tissue and SP-B protein was also decreased in experimental group than in control group (P0.05).Conclusion The levels of SP-A and SP-B in lung tissue may lower after ALI induced by open chest trauma and seawater invasion into thoracic cavity,and they which may be related to both the increased leakage of blood capillaries and the augmented local or systematic inflammatory reaction.