Riehle Kimberly J, Hoagland Vicki, Benz Whitney, Campbell Jean S, Liggitt Denny H, Langdale Lorrie A
*Department of Surgery, Veterans Administration; and Departments of †Surgery, ‡Pathology, and §Comparative Medicine, University of Washington, Seattle, Washington.
Shock. 2014 Nov;42(5):424-31. doi: 10.1097/SHK.0000000000000231.
Hepatic ischemia-reperfusion (IR) results in progressive injury; initiated by oxidative stress during ischemia and compounded by cytokine-mediated inflammation during reperfusion. Recovery requires strict regulation of these events. Recombinant human erythropoietin (rhEPO) is thought to mitigate hepatocellular IR injury by altering the nonparenchymal liver microenvironment. This study sought to identify additional mechanisms whereby rhEPO is protective after liver IR injury. Mice were treated with rhEPO (4 units/g s.c.) at the onset of partial liver ischemia and assessed for transaminase and histologic injury at intervals after reperfusion. Induction of cytokines, activation of signal transducers and activators of transcription (STATs), suppressors of cytokine signaling (Socs1, Socs3, Cis), caspase-3 activation, and heme oxygenase-1 (HO-1) expression were assessed in postischemic liver. Effects of rhEPO stimulation were further characterized in whole-liver lysates from mice undergoing rhEPO injection alone and in cultured AML-12 hepatocytes. Recombinant human erythropoietin treatment at the onset of severe (90 min) hepatic IR confirmed commensurate biochemical and histological protection without affecting tissue cytokine levels. Although Socs3 and STAT5 activation were induced in normal liver after in vivo rhEPO injection, this treatment did not augment expression beyond that seen with IR alone, and neither was induced in cultured hepatocytes treated with rhEPO. Recombinant human erythropoietin inhibited caspase-3 activation in nonparenchymal cells, whereas hepatocellular HO-1 was rapidly induced both in vivo and in vitro with rhEPO treatment. These data suggest HO-1 as a potent mechanism of rhEPO-mediated protection after liver IR, which involves both direct hepatocellular and nonparenchymal mechanisms.
肝缺血再灌注（IR）会导致进行性损伤，这种损伤始于缺血期间的氧化应激，并在再灌注期间因细胞因子介导的炎症而加剧。恢复需要对这些事件进行严格调控。重组人促红细胞生成素（rhEPO）被认为可通过改变肝脏非实质细胞微环境来减轻肝细胞IR损伤。本研究旨在确定rhEPO在肝IR损伤后发挥保护作用的其他机制。在部分肝缺血开始时，用rhEPO（4单位/克，皮下注射）对小鼠进行治疗，并在再灌注后的不同时间间隔评估转氨酶和组织学损伤情况。对缺血后肝脏中细胞因子的诱导、信号转导和转录激活因子（STATs）的激活、细胞因子信号抑制因子（Socs1、Socs3、Cis）、半胱天冬酶-3激活以及血红素加氧酶-1（HO-1）的表达进行评估。在单独接受rhEPO注射的小鼠的全肝裂解物以及培养的AML-12肝细胞中，进一步研究rhEPO刺激的作用。在严重（90分钟）肝IR开始时给予重组人促红细胞生成素治疗，证实了其在生化和组织学方面具有相应的保护作用，且不影响组织细胞因子水平。虽然在体内注射rhEPO后，正常肝脏中会诱导Socs3和STAT5激活，但这种治疗并未使表达增加超过单独IR时的水平，在用rhEPO处理的培养肝细胞中也未诱导这两种因子的激活。重组人促红细胞生成素抑制非实质细胞中的半胱天冬酶-3激活，而rhEPO治疗在体内和体外均可迅速诱导肝细胞中的HO-1。这些数据表明，HO-1是rhEPO介导的肝IR损伤后保护作用的一种有效机制，这涉及直接的肝细胞机制和非实质细胞机制。
