Activations of mitogen-activated protein kinases and regulation of their downstream molecules after rat lung transplantation from donors after cardiac death

Accepting organs donated after cardiac death (DCD) is an effective approach to the donor shortage. However, lung transplantations from DCD donors show severe rapid pulmonary graft dysfunction (PGD) followed by warm ischemiareperfusion injury (IRI). This study sought to clarify the molecular mediators in warm IRI, including activation of mitogen-activated protein kinase (MAPK) and the downstream cascades. We performed single left lung transplantation using organs from male Sprague-Dawley rats after 0 (CIT group), 30 (30WIT group), or 180 (180WIT group) minutes of warm ischemia time. Pulmonary graft functions were estimated by blood gas analysis. At 1 hour after reperfusion, the phosphorylation status of MAPKs (ERK, p38, and JNK) and the gene expression levels of transcription factors (Egr-1 and ATF-3) and immune mediators (MCP-1, MIP-2, PAI-1, ICAM-1, TNF-α, IL-1β, IL-6, and COX-2) in the grafts were examined using Western blotting and real-time polymerase chain reaction assays. Severe PGD was observed in the 180WIT group compared with transplanted lungs in the other groups, which exhibited good pulmonary graft function. ERK and JNK activations, as well as mRNA levels of transcription factors (Egr-1 and ATF3) significantly increased with greater warm ischemic times. The pattern of JNK activation correlated with the severity of PGD. MCP-1, ICAM-1, IL-1β, IL-6, and COX-2 were also up-regulated among the 180WIT group, although MIP-2 and PAI-1 showed no significant differences among the groups. We suggest that the ERK and JNK pathways may play important roles to induce the injury caused by prolonged warm ischemia followed by reperfusion in the setting of lung transplantation from DCD donors.