Stabilizing mast cells improves acute lung injury after orthotopic liver transplantation via promotion of apoptosis in polymorphonuclear neutrophils.

AIMS Postoperative pulmonary complications including acute lung injury (ALI) and acute respiratory distress syndrome have contributed to the mortality and morbidity of orthotopic liver transplantation (OLT) with unclear mechanisms. Mast cells (MCs) and polymorphonuclear neutrophils (PMNs) are the main inflammatory cells and participants in the process of ALI. The present study was designed to investigate the role of MCs and PMNs and their potential relation to ALI following OLT. MAIN METHODS Rat orthotopic autologous liver transplantation (OALT) model was designed to determine lung injury at different time points after liver reperfusion. We also evaluated the function of MCs and the effect of TNF-α and tryptase on ALI and PMN apoptosis in rats subjected to OALT. Histological scores and inflammatory factor levels as well as PMN apoptosis were measured. KEY FINDINGS Rats suffered from ALI after OALT, which was demonstrated with collapse of pulmonary architecture, pulmonary edema, and infiltration of inflammatory cells in alveolar and interstitial spaces, as well as increased levels of pro-inflammatory cytokines. ALI maximized at 8 h after OALT. However, PMN apoptosis lagged behind the pulmonary injury and maximized at 16 h after OALT, when the acute inflammation resolution initiated. MC stabilization, and tryptase and TNF-α inhibitors could significantly decrease the lung pathophysiologic scores accompanied with an increase in PMN apoptosis. SIGNIFICANCE ALI after OLT was associated with MC activation and PMN apoptosis. The ALI progression might be affected by delayed PMN apoptosis, which was related to MC activation. Induction of PMN apoptosis might alleviate ALI after OALT.