缺血或药物预处理对大鼠供肝缺血再灌注损伤的抑制作用

Both ischemic and pharmacological preconditioning decrease leukocyte/endothelial cell interactions in donor liver in rats

目的 探讨缺血预处理 (IPC)或阿霉素预处理 (DPC ,模拟IPC)对大鼠供肝延迟性保护作用的发生机制。方法 将供鼠分为 3组。IPC组 :供鼠采用肝脏预先缺血 10min后再开放 ;DPC组 :供鼠经静脉注射阿霉素 (1mg/kg体重 ) ;对照组 :供鼠用等量生理盐水注射。观察各组预处理后血红素氧化酶 1(HO 1)和热休克蛋白 70 (HSP70 )含量 ;建立上述各组大鼠原位肝移植模型 ,并设假手术对照组 ,观察肝移植后各组对供肝缺血再灌注损伤的影响。结果 IPC组HO 1、HSP70含量分别于预处理 12h和 2 4h达到高峰 ;IPC和DPC组预处理 2 4h ,诱导的HSP70、HO 1含量差异无显著性 (P >0 .0 5 )。对照组肝移植后 6h ,肝组织中ICAM 1mRNA表达和内皮细胞ICAM 1分子表达明显增强 ,髓过氧化物酶 (MPO)活性增高 ,血清中天冬氨酸转氨酶 (AST)、丙氨酸转氨酶 (ALT)、乳酸脱氢酶 (LDH)及肝组织湿重 /干重 (W/D)水平明显升高 ,和假手术组相比 ,差异有显著性 (P <0 .0 1)。IPC或DPC组肝移植后减弱了ICAM 1mRNA和蛋白表达及MPO活性 ,AST、ALT、LDH及W/D的水平亦明显降低 ,与对照组比较 ,差异有显著性 (P <0 .0 5 )。结论 IPC的延迟保护作用是通过降低中性粒细胞的粘附浸润来实现的 ,这与IPC诱导生成HSP70和HO 1有关。DPC可以模拟IPC的延迟性保护?

Objective To investigate the molecular mechanisms of delayed ischemic preconditioning (IPC) and doxorubicin preconditioning (DPC) to induce ischemic tolerance. Methods The models of sham-operation and orthotopic liver transplantation in the Wistar rats was used. IPC was administered with a 10-min ischemia followed by a 10-min reperfusion. Animals in the DPC group were pretreatd with Doxorubicin (1?mg/kg, iv). The control rats were subjected to saline treatment. The induction of HSP70 and HO-1 protein ( Western blot), the expression of ICAM-1 transcripts (RT-PCR)and ICAM-1 protein (immunohistochemistry), the activities of serum AST, ALT, LDH, and liver myeloperoxidase (MPO) , liver wet-to-dry weight ratios (W/D) were assessed.Results HO-1 expression was maximally induced at 12?h after IPC, and hardly changed until 48?h. A strong induction of HSP70 was detected at about 24 to 72?h after IPC. The levels of HO-1 and HSP70 were obviously elevated at 24?h after IPC or DPC as compared with the control ( P < 0.05 ), whereas no significant difference was found between IPC group and DPC group ( P > 0.05 ). In the control group, the transcription of ICAM-1 was significantly increased 6?h after reperfusion. Capillary endothelial cells of the livers strongly expressed ICAM-1. Activities of liver MPO were obviously elevated. IPC and DPC could significantly decrease the transcription of ICAM-1 in the livers in concurrence with the expression of ICAM-1 protein as well as the activity of MPO at 6?h after reperfusion ( P < 0.05 ). The levels of liver enzymes and W/D were significantly reduced in the IPC and DPC goups ( P < 0.05 ). Conclusion IPC and DPC protect against hepatic ischemia-reperfusion injury by suppressing endothelial/leukocyte interaction. Induction of HO-1 and HSP70 in delayed IPC and DPC may play an critical role for the protection.