The Study Of Matrix Metalloproteinases-9 In Lung Injury During Cardiopulmonary Bypass

Objectives: To explore the relationship between the plasma levels of MMP-9 and the acute lung injury during CPB in the perioperative time.Methods: Male SD rats (450-550g,n=30) were anaesthetized, mechanically ventilated, and used to establish the full-flow CPB model. Plasma levels of MMP-9 were detected 0min, 15min, 30min, 60min after the beginning of CPB, and 30min post CPB. The expression of MMP-9 in the lung before and post CPB was detected by electron microscope and immunohistochemistry. Human plasma twenty patients undergoing CPB was obtained and collected at the beginning of CPB, 5 minutes after the initiation of CPB, the termination of CPB, 1 hour and 6 hours post CPB. Plasma levels of MMP-9 and TNF-α were analyzed by standard enzyme-linked immunosorbent assay (ELISA).Results: Plasma MMP-9 levels in the rat model were significantly increased after the start of CPB and peaked at the end of CPB. The expression of MMP-9 in the lung tissue was also significantly increased. Plasma MMP-9 and TNF-a in the patients significantly increased after the start of CPB and peaked at the end. There was obvious positive correlation between plasma MMP-9 and TNF-a perioperatively.Conclusion: MMP-9 is released and synthesized obviously during and after CPB. CPB can induce the expression of MMP-9 in the lung significantly. The releasing and activation of MMP-9 may contribute to alterations in tissue homeostasis in the early postoperative period of acute lung injury.