肝移植相关的缺血再灌注损伤

随着新型免疫抑制剂的临床应用和血管吻合技术的提高,临床肝移植成功率大大提高,而严重肝脏缺血再灌注损伤所引起的移植肝功能受损始终未能解决,影响肝移植的效果。因此本文对肝脏缺血再灌注损伤的分类、机制、预防及治疗等方面予以综述。     

肝脏缺血再灌注损伤发生机制及药物干预研究进展

缺血再灌注损伤是许多因子参与的复杂的病理生理过程,是影响肝移植、肝脏叶段切除术后肝功能的一个多因素过程。本文主要阐述肝脏缺血再灌注损伤的发病机制及药物预处理对其的防治。     

The role of matrix metalloproteinase inhibitors in ischemia-reperfusion injury in the liver

Liver ischemia-reperfusion injury is characterized by cell necrosis and apoptosis and by profound modifications in the extracellular matrix (ECM). During the complex series of events that take place both during ischemia and when normal blood flow is restored (reperfusion), a concerted regulation of release and activation of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) mainly by stellate cells, Kupffer cells and inflammatory cells leads first to endothelial cell injury and subsequent infiltration of neutrophils into the wounded area. Later, MMP activation causes degradation of extracellular matrix components of the liver, mainly collagen and fibronectin, altering tissue architecture. The fibrosis that can result after liver injury is also dependent on the imbalance between MMPs and TIMPs and to new collagen deposition. Several experimental models of liver ischemia-reperfusion injury have demonstrated protective effects of MMP inhibitors in terms of cell necrosis, apoptosis and rearrangement of the extracellular matrix. This review summarizes current knowledge of MMP biology, with particular attention to the most recent evidence of novel, non-extracellular matrix MMP substrates involved in inflammation and cell cycle regulation. An overview of MMP and TIMP expression and activation in hepatic ischemia-reperfusion injury is provided. The analysis of such provides a rational basis for MMP inhibition as a viable strategy to prevent liver injury.     

血小板活化因子在肝损伤中的作用

血小板活化因子 (PAF)在肝脏中主要表现为增加肝脏血管阻力及糖原分解两大作用 ,同时还可介导超氧化物的释放、花生四烯酸的代谢、细胞因子的生成等。此外 ,PAF与肝缺血 再灌注损伤及内毒素损伤肝脏有着极密切的关系。     

Effect of intraportal verapamil infusion on hepatic ischemia-reperfusion injury.

Removal of free oxygen radicals, generated during reperfusion of an ischemic organ by scavengers protects the tissue from reperfusion injury. The calcium channel blocker verapamil is an effective cytoprotective agent, preventing against reperfusion injury. The effects of verapamil were investigated previously using hepatic, renal or cardiac ischemia-reperfusion injury models. We investigated the effects of intravenous and intraportal administration of verapamil in prevention from the injury caused by free oxygen radicals generated during hepatic ischemia-reperfusion in rats. Thirty six male Sprague-Dawley rats after laparotomy were subjected to hepatic ischemia for 30 and 45 min followed by 60 min of reperfusion. Two minutes before ischemia the rats were pretreated by intravenous or intraportal administration of verapamil. The levels of glutathione and thiobarbituric acid reacting substances (TBARs) referred to as malonyldialdehyde (MDA) and the serum levels of transaminases were measured in liver tissue 1 and 24 h after the onset of reperfusion. Statistical analysis of the data by Student's t-test showed statistically significant differences between the group pretreated intraportally with verapamil and the other groups. Verapamil given intraportally exerted more beneficial effect. Therefore, we conclude that intraportal verapamil administration reduces the ischemia-reperfusion injury caused by free oxygen radicals.     

肝移植患者术中氧自由基相关指标的变化

目的：研究在肝移植术中氧自由基对肝脏缺血再灌注损伤的作用。方法：测定比较18例肝移植患者术前、无肝期、再灌注后1h血浆中脂质过氧化物(LPO)、超氧化物歧化酶(SOD)、总抗氧化能力(TAC)、一氧化氮水平(NO)，分析其变化。结果：再灌注后LPO和TAC下降，SOD和NO升高。结论：氧自由基在肝移植缺血再灌注损伤中有重要作用，再灌注后，激活了保护机制，手术中输血及某些药物的使用也可以减轻自由基损害，对机体具有保护作用。     

丙泊酚对大鼠肠缺血再灌注损伤时肝细胞凋亡及Caspase-3的影响

目的探讨丙泊酚对大鼠肠缺血再灌注损伤时肝细胞凋亡及Caspase-3的影响。方法成年健康Wistar大鼠42只,随机分为3组:实验对照组(C组,6只)、肠缺血再灌注组(IR组,18只)、丙泊酚干预组(P组,18只)。各组根据再灌注时间分为1,3,6h三个时相。通过夹闭肠系膜上动脉制作肠缺血再灌注损伤模型,实验结束后即刻取肝左叶做标本。用免疫组织化学法检测Caspase-3蛋白表达量,末端转移酶标记技术(TUNEL)法检测肝细胞凋亡指数(AI)。结果与C组比较,IR组和P组肝组织Caspase-3蛋白含量、AI均增加(P<0.05);与IR组比较,P组Caspase-3蛋白表达减少、AI减少(P<0.05)。结论丙泊酚可以下调大鼠肠缺血再灌注时Cas-pase-3蛋白表达,使肝细胞凋亡减轻,从而对肝损伤有一定的保护作用。     

Role of kupffer cells in cold/warm ischemia-reperfusion injury of rat liver

The mechanisms of liver injury from cold storage and reperfusion are not completely understood. The aim of the present study was to investigate whether the inactivation of Kupffer cells (KCs) by gadolinium chloride (GdCl3) modulates ischemia-reperfusion injury in the rat liver. Hepatic function was assessed using an isolated perfused rat liver model. In livers subjected to cold storage at 4 degees C in University of Wisconsin solution for 24 hrs and to 20 min rewarm-ing ischemia, oxygen uptake was markedly decreased, Kupffer cell phagocytosis was stimulated, releases of purine nucleoside phosphorylase and lactate dehydrogenase were increased as compared with control livers. Pretreatment of rats with GdCl3, a selective KC toxicant, suppressed Kupffer cell activity, and reduced the grade of hepatic injury induced by ischemia-reperfusion. While the initial mixed function oxidation of 7-ethoxycoumarin was not different from that found in the control livers, the subsequent conjugation of its meta-bolite to sulfate and glucuronide esters was suppressed by ischemia-reperfusion. GdCl3 restored sulfation and glucuronidation capacities to the level of the control liver. Our findings suggest that Kupffer cells could play an important role in cold/warm ischemia-reperfusion hepatic injury.     

The protecting effects and mechanism of betaine hydrochloride on hepatic ischemia-reperfusion injury in rats

Objective To study the protecting effects and mechanism of betaine hydrochloride on hepatic ischemia-reperfusion injury in rats.Methods Fourty SD rats were randomly divided into 5 groups(8 animals in each group):sham-operated control group(A),hepatic ischemia-reperfusion group(B),200 mg·kg-1 400 mg·kg-1 800 mg·kg-1 betaine hydrochloride+hepatic ischemia-reperfusion group(C、D、E).betaine hydrochloride was administered to animals byoral route in group C、D、E for 7 days before ischemia.A、B group was administered with NS.Made the animal model of part hepatic ischemia-reperfusion.Serum alanine aminotransferase(ALT),aspartate aminotransferase(AST)levels in the blood and themalondialdehyde(MDA),superoxide dismutase(SOD),protein content in hepatic tissue were determined after the liver had been reperfused for 24 hours;the hepatic tissue was examined under lightmicroscope and the cell apoptosis was demonstrated with flow cytometry.Results ALT,AST,MDA increased and SOD decreased significantly in B group when compared those in the A group(P<0.05),Hepatic apoptosis was significantly increased;ALT,AST,MDA decreased and SOD increased significantly in betaine hydrochloride 200 mg·kg-1(C)group when compared those in the B group(P<0.05).Hepatic apoptosis was significantly lower,The histologic changes of the liver tissue under lightmicroscope in the C group was more easer than in the I/R group(B).Conclusions Betaine hydrochloride has the ability to scavenge oxygen free radical(OFR),reduce lipid peroxidation and inhibition of apoptosis.So it can protect the rats liver damaged by ischemia-reperfusion.     

丙泊酚的作用机制及临床新应用

作为一种静脉全麻药,丙泊酚因起效迅速、作用时间短、清醒快而完全、副作用少等优点自上世纪80年代进入临床以来应用广泛。但近年研究发现,除了麻醉作用外,丙泊酚还有许多其他非麻醉效应。丙泊酚具有减少脑缺血时神经元的损伤,保护缺血器官,抑制血小板聚集,减少术后呕吐,免疫调节,止痛等效应。这些麻醉外效应将来可能进一步扩大丙泊酚的临床应用范围。本文对近年来对丙泊酚的药理学研究机制及新的临床应用进行综述。     

HSP70在经热应激预处理后减少大鼠肝脏缺血再灌注损伤过程中的作用

目的　探讨热应激预处理能够减少肝脏缺血再灌注损伤的机制,以期寻找减轻肝脏缺血再灌注损伤的有效措施。方法　建立大鼠肝脏缺血再灌注损伤模型。将42只大鼠随机分为6组:①正常对照组(N);②槲皮素组(Q):腹腔注射槲皮素(quercetin, 7mg·kg-1 );③肝脏缺血再灌注(ischemi areperfusion,I/R)组(I);④热应激预处理组(H+I):缺血再灌注前16h给予热应激预处理;⑤槲皮素+热应激预处理组(Q+H+I):缺血再灌注前16h先给予槲皮素腹腔注射(7mg·kg-1 )再给予热应激处理;⑥槲皮素+缺血组(Q+I):缺血再灌注前16h给予槲皮素腹腔注射(7mg·kg-1 )。观察以上各组大鼠在肝脏缺血再灌注6h后热休克蛋白70(Heatshockprotein70, HSP70 )的表达,血清谷丙转氨酶(ALT)、谷草转氨酶(AST)的活性及肝脏组织形态学改变。结果　大鼠肝脏HSP70表达由高到低依次为:H+I组、I组、Q+H+I组、I+Q组、Q组、N组;而检测血清ALT、AST含量由高到低依次为:Q+I组、I组、Q+H+I组、H+I组、Q组、N组;肝脏组织形态学的改变显示与上述血中ALT、AST含量变化相对应。结论　HSP70在经热应激预处理后减少肝脏缺血再灌注损伤的过程中起重要的作用。     

Serotonin activity and liver dysfunction following hepatic ischemia and reperfusion

Serotonin (5-hydroxytriptamine; 5-HT), which is stored in platelets, is known to induce vasoconstriction and promote platelet aggregation. More recent studies suggest that serotonin also plays a role in organ injury after ischemia and reperfusion. The purpose of this study was to characterize the role of 5-HT and platelet function in the pathogenesis of hepatic ischemia-reperfusion injury. Under the portocaval shunt, 60 or 90 min of complete warm ischemia of canine liver was induced by Pringle's maneuver, followed by reperfusion for 120 min. Time-matched, sham-operated animals served as controls. Hepatic tissue blood flow and various parameters of hepatic vein blood (ALT, LDH, platelet count and platelet aggregation) were measured before and after reperfusion. 5-HT levels in portal vein and hepatic vein were also assayed. Hepatic ischemia and reperfusion resulted in liver hypoperfusion, hepatocellular dysfunction, increased platelet aggregation, increased 5-HT levels, and hepatic microcirculation injury. These results suggest that the endogenous 5-HT released from platelet may contribute to liver tissue hypoperfusion following hepatic ischemia-reperfusion.     

The biology of exhaled nitric oxide (NO) in ischemia-reperfusion-induced lung injury: a tale of dynamism of NO production and consumption

The main objective of this paper is to review the potential diagnostic roles of exhaled nitric oxide (NO) in evaluating ischemia-reperfusion-induced lung injury associated with cardiac surgery. We shall start by elaborating on current clinical practice of cardiac surgery and to arrive at the conclusion that clinically important ischemia-reperfusion injury is a common scenario of many forms of these surgical procedures. We shall conclude this part by establishing the clinical need for biomarkers of inflammation in cardiothoracic surgery and by proposing that exhaled NO could be an important new addition to our anaesthetic monitoring repertoire based on our expertise with exhaled breath monitoring. We shall then take a closer look at mechanisms of ischemia-reperfusion injury and will propose the role of reactive oxygen and nitrogen species as mediators and biomarkers of acute lung injury. This analysis will provide a good opportunity to highlight major potential mechanisms of altered NO production and bioactivity of NO. We shall conclude that multiple relevant mechanisms may either lead to increased production of NO or enhance consumption of NO, leaving us with the paradigm that NO maybe used either as a positive or negative biomarker of inflammation. In order to explore this dilemma further, we will investigate the predominant effect of oxidative stress on NO bioactivity in cell culture models of ischemia-reperfusion injury. We will then turn to animal models of ischemia-reperfusion injury to elucidate the ultimate effects of this condition on lung NO production and concentrations of NO in the lung. Finally, we shall complete this journey by highlighting the human relevance of these observations by reviewing our own experience at Harefield Hospital, UK, and that of others, regarding exhaled NO in ischemia-reperfusion injury associated with cardiac surgery and lung transplantation.     

新型糖原磷酸化酶抑制剂-山楂酸对小鼠脑缺血-再灌注的保护作用研究

目的：研究糖原磷酸化酶抑制剂-山楂酸对缺血性脑损伤的保护作用,初步探讨糖原磷酸化酶抑制剂的脑缺血保护机制。方法：采用合并迷走神经结扎双侧颈总动脉造成小鼠急性不完全性脑缺血-再灌注模型,测定脑组织匀浆乳酸含量、相关生化指标以及肝糖原含量。结果：山楂酸灌胃给药以后能降低脑组织乳酸、丙二醛含量,提高超氧化物歧化酶、乳酸脱氢酶活力,还能对抗缺血期间的肝糖原降解。结论：山楂酸对缺血性脑损伤具有一定保护作用,其抗脑缺血作用至少是与通过部分抑制糖酵解并进而减轻代谢性酸中毒有关。     

The role of thiols in liver ischemia-reperfusion injury

Thiol-containing compounds have an essential role in many biochemical reactions due to their ability to be easily oxidised and then quickly regenerated. Main representatives are glutathione, lipoic acid and thioredoxin which are synthesised de novo in mammalian cells. N-acetylcysteine and Bucillamine are synthetic thiols which have been administered in experimental and clinical studies for treatment of conditions associated with oxidative stress. Ischemia and reperfusion (I/R) injury is characterised by significant oxidative stress, characteristic changes in the antioxidant system and organ injury leading to significant morbidity and mortality. I/R occurs in a variety of clinical settings such as liver resection, organ transplantation, haemorrhagic shock with fluid resuscitation, heart surgery, myocardial infarction followed by reperfusion and laparoscopic surgery. In these circumstances, the administration of antioxidant agents such as thiols, could provide protection from the harmful effects of I/R injury. However, the ability of thiol compounds to reduce free radicals is associated with the formation of thiyl radicals and the rate and efficiency of removal of thiyl radicals has a critical effect on antioxidant or prooxidant actions of thiols in the cells. The aim of this review is to present the mechanisms by which thiols act as antioxidants and signalling molecules and the experimental and clinical evidence regarding their role in I/R injury with a particular emphasis on liver I/R. The current evidence suggests that thiols ameliorate I/R injury and that their clinical significance should be further evaluated in large scale randomised clinical trials.     

A novel antioxidant non-steroidal anti-inflammatory agent protects rat liver against ischemia-reperfusion injury

Liver ischemia followed by reperfusion is an important and common clinical event. A major mechanism is leukocyte adhesion to endothelium followed by release of reactive oxygen metabolites. The aim of this study was to determine the effects of a novel antioxidant ethylenediamine derivative with anti-inflammatory properties (compound IA) on an imitated clinical setting of acute hepatic ischemia-reperfusion injury. Eight groups of rats were subjected to a model of hepatic ischemia that was produced by occluding for 30 min the portal vein and hepatic artery. At the end of ischemia, compound IA was administered intravenously and the clamps were removed allowing reperfusion for 60 min or 24 h. The effect of compound IA was evaluated by histopathological examination, lipid peroxidation and plasma levels of liver enzymes. Administration of compound IA resulted in significantly less histological damage in liver tissue after 30-min ischemia followed by 60-min and 24-h reperfusion. Ischemia followed by 60 min of reperfusion increased lipid peroxidation compared to the sham-operated and the non-ischemic group. This increase was attenuated in the group treated with compound IA. Serum enzyme levels were significantly higher in the reperfusion groups compared to the non-ischemic groups and diminished after treatment. Compound IA exerted a protective effect on hepatic reperfusion injury in rats. Compound IA is believed to act by means of its potent antioxidant and anti-inflammatory activities.     

钙通道阻滞剂抗肝缺血—再灌注损伤作用机制的实验研究

目的 探讨钙通道阻滞剂（ＣＣＥＢ）对肝缺血一再灌注损伤（ＨＩＲＩ）防治作用的机制。方法制备家兔ＨＩＲＩ模型,动态观察维拉帕米（ＶＰ）和地尔硫卓（ＤＴ）对肝组织及血中黄嘌呤氧化酶（ＸＯ）、超氧化物歧化酶（ＳＯＤ）活性及脂质过氧化物（ＬＰＯ）浓度的影响。结果 ＶＰ组和ＤＴ组ＯＸ活性及ＭＤＡ含量分别显著低于对照组（均Ｐ＜０．０１）,而ＳＯＤ活性与对照组比较均无显著性差异（均 Ｐ＞ ０．０５）。结论 ＣＣＥＢ抗 ＨＩＲＩ的机制与其降低 ＸＯ活性、抑制脂质过氧化反应密切相关。     

丙泊酚对大鼠肝脏缺血再灌注损伤Bcl-2和P53表达的影响

目的探讨丙泊酚对大鼠肝脏缺血再灌注损伤时Bcl-2和P53表达的影响及其保护作用。方法健康成年雄性SD大鼠54只,随机分为3组:假手术组(Ⅰ组)、缺血再灌注组(Ⅱ组)、丙泊酚组(Ⅲ组)。每组根据再灌注时间不同又分为3个时间段(1、2、3h)。制作70%肝脏缺血再灌注模型,实验结束后即刻取肝左叶做标本。用免疫组织化学法检测Bcl-2与P53蛋白表达量,原位细胞凋亡检测(TUNEL)法检测肝细胞凋亡指数(AI),光镜下观察肝组织的病理学变化。结果与Ⅰ组比较,Ⅱ、Ⅲ组肝组织Bcl-2、P53蛋白含量、凋亡指数差异均有统计学意义(P<0.05);与Ⅱ组比较,Ⅲ组Bcl-2蛋白表达增加、P53蛋白表达和AI减少(P<0.05);光镜下Ⅲ组的肝细胞病理学变化轻于Ⅱ组。结论丙泊酚可以通过调节Bcl-2、P53蛋白表达,使肝细胞凋亡减轻,从而对大鼠缺血再灌注肝脏有一定的保护作用。     

甜菜碱对大鼠肝脏缺血-再灌注损伤的作用

目的观察甜菜碱对大鼠肝脏缺血-再灌注损伤的作用。方法 40只SD大鼠随机分为假手术组,模型组,甜菜碱200、400、800 mg·kg^-1组(均n=8)。甜菜碱各剂量组于造模前7 d灌胃给予相应剂量甜菜碱,假手术组和模型组给予生理盐水。夹闭门静脉、肝动脉分支40 min,再灌注24 h制大鼠部分肝脏缺血-再灌损伤模型。检测血清中丙氨酸转氨酶(ALT)、天冬氨酸转氨酶(AST)水平和肝脏组织中丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性,流式细胞术检测细胞凋亡水平,Western blot法检测凋亡相关蛋白p53、cl-caspase-3和Bcl-2的表达,经HE染色观察肝脏组织病理学改变。结果与假手术组比较,模型组大鼠血清ALT和AST水平显著上升(P <0.01),肝脏组织中MDA含量显著增加、SOD活性降低(P <0.01),肝细胞凋亡率显著增高(P <0.01)。与模型组比较,甜菜碱400、800 mg·kg^-1组ALT和AST水平显著降低(P <0.05,P <0.01),肝组织中MDA含量显著降低、SOD活性显著增强(P <0.05),肝细胞凋亡率下降(P <0.05,P <0.01),p53、cl-caspase-3、Bax表达显著降低(P <0.05)。结论甜菜碱可改善肝脏缺血-再灌注损伤大鼠肝功能,可能与其抗氧化、抑制肝细胞凋亡有关。     

An injury of the liver caused by ischemia-reperfusion in rat liver

Cellular damage of various organs by ischemia following reperfusion is assumed to be at least in part due to lipid peroxidation in biomembranes, and oxygen-derived free radicals play a major role. The level of lipid peroxides in liver tissue increased during 90-min ischemia. When reflow of hepatic blood was allowed, a greater increase in the lipid peroxides was observed. Similar increases were obtained in several serum markers (GOT, GPT and LDH) during the period of ischemia or ischemia-reperfusion. In addition, levels of cytochrome p-450 and NADPH cyt. c reductase activity decreased in proportion to the decrease in microsomal proteins during ischemia or ischemia-reperfusion. On the other hand, superoxide dismutase in blood was significantly increased by ischemia-reperfusion. Rats died within 2 days after liver ischemia of 90 min, while all animals subjected to 30-min ischemia survived. Histopathological examinations indicated that extensive coagulation with erythrocytes occurred and the extent was dependent on the time of ischemia. The liver injury by ischemia-reperfusion could be a useful experimental model for studying liver injury induced by free radicals, for developing hepatoprotective drugs, or for investigating liver transplantation.