A rise of MMP-2 and MMP-9 in bronchoalveolar lavage fluid is associated with acute lung injury after cardiopulmonary bypass in a swine model

Abstract

Postoperative acute lung injury (ALI) contributes to the morbidity and mortality following cardiopulmonary bypass (CPB). To determine whether the presence of matrix metalloproteinases (MMPs) is associated with ALI after CPB, MMP-2 and MMP-9 activities in bronchoalveolar lavage fluid (BALF) were compared with parameters indicating impaired gas exchange. In a prospective study, 17 minipigs were subjected to CPB for 60 min. Before and at five and 180 min after CPB, MMP-2 and MMP-9 were assayed in BALF and the arterial-alveolar gradient of oxygen tension (AaDO₂), the pulmonary capillary wedge pressure (PCWP) and the water content of lung tissue samples (Wt) were evaluated and compared with baseline values. MMP-2 and MMP-9 increased significantly 5 minutes (2.1- and 6.2-fold, respectively) and 180 minutes (3.4- and 14.3-fold, respectively) post-CPB. AaDO₂ and Wt, but not PCWP, increased significantly 180 minutes after CPB and only AaDO₂, but not PCWP or Wt, was significantly correlated with MMP-2 (r /0.66, p /0.006) and MMP-9 (r /0.62, p /0.01). In conclusion, high levels of MMP-2 and MMP-9 in the pulmonary compartment are associated with ALI after CPB.