ABSTRACT
The c-Jun N-terminal kinase (JNK) pathway enhances graft injury after liver transplantation (LT). We hypothesized that the JNK2 isoform promotes graft injury via the mitochondrial permeability transition (MPT). Livers of C57BL/6J (wild-type, WT) and JNK2 knockout (KO) mice were transplanted into WT recipients after 30 h of cold storage in UW solution. Injury after implantation was assessed by serum ALT, histological necrosis, TUNEL, Caspase 3 activity, 30-day survival, and cytochrome c and 4-hydroxynonenal immunostaining. Multiphoton microscopy after LT monitored mitochondrial membrane potential in vivo. After LT, ALT increased three times more in WT compared to KO (p < 0.05). Necrosis and TUNEL were more than two times greater in WT than KO (p < 0.05). Immunostaining showed a >80% decrease of mitochondrial cytochrome c release in KO compared to WT (p < 0.01). Lipid peroxidation was similarly decreased. Every KO graft but one survived longer than all WT grafts (p < 0.05, Kaplan-Meier). After LT, depolarization of mitochondria occurred in 73% of WT hepatocytes, which decreased to 28% in KO (p < 0.05). In conclusion, donor JNK2 promotes injury after mouse LT via the MPT. MPT inhibition using specific JNK2 inhibitors may be useful in protecting grafts against adverse outcomes from ischemia/reperfusion injury.
Subject(s)
Liver Transplantation/adverse effects , Mitochondria/metabolism , Mitogen-Activated Protein Kinase 9/metabolism , Reperfusion Injury/etiology , Transplants/adverse effects , Alanine Transaminase/blood , Aldehydes/metabolism , Animals , Apoptosis , Caspase 3/metabolism , Immunohistochemistry , Isoenzymes/genetics , Isoenzymes/metabolism , Lipid Peroxidation , Liver Transplantation/pathology , Male , Membrane Potential, Mitochondrial/physiology , Mice , Mice, Inbred C57BL , Mice, Knockout , Necrosis/pathology , Permeability , Prospective Studies , Random Allocation , Reperfusion Injury/metabolism , Reperfusion Injury/pathologyABSTRACT
Endothelial nitric oxide synthase (eNOS) plays a role in microcirculatory and immunomodulatory responses after warm ischemia/reperfusion. We hypothesized that eNOS is essential to maintain microcirculation, attenuate macrophage infiltration and decrease graft injury after liver transplantation. Liver transplantation was performed after 18 hours of cold storage in University of Wisconsin (UW) solution from wildtype and eNOS-deficient (B6.129P2-Nos3(tm/Unc)/J) donor mice into wildtype mice. Serum ALT, necrosis by histology, apoptosis by TUNEL, and macrophage infiltration by immunostaining against F4/80 antigen were determined 2 to 8 hours after implantation. Hepatic microcirculation was investigated after 4 hours by intravital confocal microscopy following injection of fluorescein-labeled erythrocytes. After sham operation, livers of wildtype and eNOS-deficient mice were not different in ALT, necrosis, apoptosis, macrophage infiltration, and microcirculation. After transplantation, ALT increased >3 times more after transplantation of eNOS-deficient livers than wildtype livers. Necrosis was >4 times greater, and TUNEL and F4/80 immunostaining in nonnecrotic areas were 2 and 1.5 times greater in eNOS-deficient donor livers, respectively. Compared with wildtype and eNOS sham-operated mice, sinusoidal blood flow velocity increased 1.6-fold after wildtype transplantation, but sinusoidal diameter was not changed. After transplantation of eNOS-deficient livers, blood flow velocity and sinusoidal diameter decreased compared with transplanted wildtype livers. These results indicate that donor eNOS attenuates storage/reperfusion injury after mouse liver transplantation. Protection is associated with improved microcirculation and decreased macrophage infiltration. Thus, eNOS-dependent graft protection may involve both vasodilatory and innate immunity pathways.
