End-Ischemic Hypothermic Oxygenated Perfusion Attenuates Ischemia Reperfusion Injury to Rat Livers Donated After Cardiac Death Through the Regulation of Protein Phosphatase 2A Related Apoptosis and Autophagy.

BACKGROUND: Hypothermic oxygenated perfusion (HOPE) is a promising technology to improve donated after cardiac death (DCD) liver graft. It was found that protein phosphatase 2A (PP2A) could regulate autophagy and apoptosis, which play a pivotal role in hepatic ischemia reperfusion injury (IRI). In this study, we aim to explore whether PP2A take part in the mechanism that reduces organ damage after HOPE.

METHOD: Adult male Sprague Dawley rats were divided into four groups at random. DCD livers of HOPE group were preserved in a HOPE system after 23 hours of cold storage (CS). All groups' livers were reperfused in an isolated perfused rat liver (IPRL) system for 1 hour at 37°C. After reperfusion, markers related to IRI and protein expression of PP2A related pathway were examined. BRL-3A cells were cultured and incubated with different concentrations H2O2 (0, 50 μM and100 μM). The cellular production of Reactive Oxygen Species (ROS) was detected via the fluorescent intensity of 2,7-Dichlorodihydrofluorescein diacetate (DCFH-DA), and PP2A related pathway protein expression was measured.

RESULTS: HOPE group suffered the lighter IRI when compared with CS group, evidenced by the lower hepatocytes injury degree, apoptosis rate, and oxidative stress. Further, compared with CS group, the PP2A and ERK1/2 related autography pathway activation of HOPE group was higher, while the JNK and p38 related apoptosis pathway was down-regulated. Cellular experiment showed that mild oxidative stress (50 μM H2O2) could activate the expression of PP2A and autography pathway protein. Severe oxidative stress (100 μM H2O2) shown the opposite regulation effect.

CONCLUSION: Through reducing oxidative stress, HOPE attenuates IRI to rat DCD livers via activating PP2A related autography pathway and inhibiting apoptosis pathway.