细胞凋亡与肝移植缺血再灌注损伤

背景：肝脏缺血再灌注损伤是影响肝脏移植效果的重要因素,细胞凋亡是移植肝缺血再灌注损伤的重要机制之一。 目的：就近年来细胞凋亡与移植肝缺血再灌注损伤的研究做一综述,为抗细胞凋亡在减轻器官缺血再灌注损伤的临床应用提供参考依据。 方法：由第一作者检索1990/2010 PubMed数据库及中国期刊全文数据库有关细胞凋亡及器官移植缺血再灌注损伤的关系的文献,检索词为“apoptosis,organ transplantation,ischemia-reperfusion injury”。排除重复性研究。计算机初检得到339篇文献,最终纳入39篇文献进行下一步分析。 结果与结论：文章从肝脏移植缺血再灌注损伤中的细胞凋亡,移植肝缺血再灌注损伤中细胞凋亡发生的机制,移植肝缺血再灌注损伤中细胞凋亡的基因表达变化,抗凋亡治疗与防治肝移植缺血再灌注损伤几方面进行了叙述。细胞凋亡与移植肝缺血再灌注损伤有着密切的关系。而抑制细胞凋亡可以有效的减轻移植肝的缺血再灌注损伤,对提高移植物的存活率有着重要的意义。     

缺血预处理预防肝细胞分离过程中的缺血再灌注损伤

背景：缺血预处理能否减轻肝细胞分离过程中的缺血再灌注损伤及改善供体残留肝脏功能? 经检索国内外罕见这方面的研究。 目的：探讨缺血预处理对分离肝细胞及供鼠残肝缺血再灌注损伤的防治作用。 方法：12 只SD大鼠随机分为2组：单纯肝部分切除组和缺血预处理组,各6只。采用改良四步胶原酶灌注法分离上述切除肝脏肝细胞,同时收集术前和术后1 d大鼠的血清。 结果与结论：缺血预处理组切除肝脏分离肝细胞成活率、增殖活性及白蛋白合成、超氧化物歧化酶水平显著高于单纯肝部分切除组(P < 0.05),而乳酸脱氢酶、谷丙转氨酶、丙二醛水平显著减少(P < 0.05);与单纯肝部分切除组比较,缺血预处理组大鼠血清白蛋白、乳酸脱氢酶、谷丙转氨酶、超氧化物歧化酶、丙二醛水平差异无显著性意义(P均> 0.05)。结果表明缺血预处理能减轻肝细胞分离过程中的缺血再灌注损伤,其机制可能与其自身缺血性预适应、抗氧化、清除氧自由基的能力相关,但对供鼠肝部分切除后残肝功能的影响不明显。     

小鼠肠缺血再灌注时肝组织一氧化氮的变化

目的：观察小鼠肠缺血再灌注时肝组织一氧化氮含量的变化,探讨一氧化氮在肠缺血再灌注时的作用。方法：动物分对照组,缺血60 min、再灌注30 min、再灌注60 min组。检测肝组织匀浆一氧化氮代谢产物NO₂^-的变化。结果：肝组织匀浆一氧化氮水平在缺血60 min时明显高于对照组,再灌注30min、再灌注60 min组与对照组相比无显著差异。结论：小鼠肠缺血时肝组织一氧化氮水平升高,提示一氧化氮可能参与小鼠肠缺血再灌注时肝组织损伤过程,对肠缺血再灌注损伤时的肝脏可能有保护作用。     

预处置对急性缺血再灌注肝脏

目的:探讨预处置对缺血再灌注损伤肝脏的防护及其机制。方法:随机将家兔分为对照组、缺血再灌注组和预处置组,复制肝缺血再灌注损伤(HIRI)模型,观察反复3次缺血5 min再灌注5 min(预处置)后再缺血45 min再灌注45 min,对血浆、肝组织一氧化氮(NO)和丙二醛(MDA)水平、谷丙转氨酶(ALT)值及肝细胞形态学改变的影响。结果:肝缺血再灌注期间,预处置组血浆及肝组织NO水平明显高于缺血再灌注组(P＜0.05);而MDA水平和血浆ALT均显著低于缺血再灌注组(P＜0.05和P＜0.01);且与仅行游离、不阻断肝血流的对照组比较均无明显差异;肝细胞形态学异常改变也明显减轻。结论:预处置可通过提高体内NO水平及降低体内氧自由基水平而减轻HIRI。     

苦参碱通过调节Bcl-2/Bax的平衡抑制大鼠缺血再灌注引起的肝细胞凋亡

目的肝脏缺血再灌注损伤是肝脏切除手术中最常见的并发症,由于激发细胞异常凋亡,常导致肝功能不全甚至引起死亡。本研究旨在揭示肝脏缺血再灌注损伤发生过程中苦参碱参与调节凋亡蛋白Bcl-2/Bax平衡的分子机制。方法健康成年SD大鼠45只,随机分为3组:一组作为空白对照组(SO组,n=15),不阻断肝脏血流;另外2组大鼠行夹闭门静脉和肝动脉缺血70 min后进行再灌注方法建立HIRI模型(缺血再灌注损伤模型),以缺血/再灌注+生理盐水组为对照组(NS组),缺血/再灌注+苦参碱组为实验组(MT组)。MT组在夹闭门静脉和肝动脉前经门静脉主干注入苦参碱。NS组注入生理盐水,阻断供血1h后恢复灌注,在恢复灌注2 h后采集标本行mRNA及Western blot检测。结果 qRT-PCR结果显示,正常对照SO组Bcl-2 mRNA表达水平显著高于Bax,在肝脏缺血再灌注模型组NS组中,高Bcl-2表达水平受到抑制,Bax表达水平显著高于Bcl-2。当行苦参碱干预后,Bax mRNA水平显著下降(MT组),基本接近SO组Bax水平。Western blot验证结果与mRNA水平结果相似。结论苦参碱显著抑制大鼠缺血再灌注引起的肝细胞凋亡,该途径可能由于苦参碱参与调节Bcl-2/Bax的平衡所致。     

量子氧合血对肝缺血再灌注损伤的保护作用

作者建立了兔肝脏缺血再灌注模型,于阻断入肝血流前输注量子氧合血(QOB),与对照组比较,观察肝脏缺血前后肝静脉、下腔静脉血气变化及组织SOD、MDA含量变化.结果表明,对照肝脏缺血25min时肝静脉血表现为极严重的酸中毒,肝脏几乎处于无氧状态,而QOB组仅表现为轻度酸中毒,肝组织内仍维持足够的氧供.另外,QOB组肝组织内SOD总活力明显提高,肝组织内MDA的生成也明显得到抑制,与对照组比较差异极显著(P<0.01).本研究认为,肝切除前或手术中应用QOB,具有较强的抗肝脏缺血再灌注损伤的防治效应.     

肝缺血再灌注损伤和氯丙嗪的保护作用—黄嘌呤脱氢酶活性的组化观察

本文用组织化学方法观察大鼠肝脏缺血不同时间后再灌注时对黄嘌呤脱氢酶(Xanthlne Dehydrogenase简称XDase)活性的影响,同时观察氯丙嗪的保护作用。结果表明,短时间(0.5小时)肝缺血后再灌注,XDase活性和HE染色都无异常改变。长时间(2小时)肝缺血,达到不可逆性损伤后再灌注3小时,可使XDase活性明显减低,再灌注24小时后,HE染色有大面积肝细胞凝固性坏死,氯丙嗪对这种改变有明显的保护作用。     

常温肝脏缺血再灌注损伤防治的实验研究

目的和方法：配制一种肝保护液，１００ｍＬ主要含有果糖７５ｇ、谷胱苷肽１５ｇ、别嘌呤醇２５ｇ、维生素Ｅ０３ｇ、地塞米松１０ｍｇ、川芎嗪０４ｇ、山莨菪碱１０ｍｇ和丹参２０ｍＬ。采用大鼠常温肝缺血６０ｍｉｎ－再灌注模型，治疗组４０只大鼠于缺血前１０ｍｉｎ和再灌注前１０ｍｉｎ，静注肝保护液１ｍＬ／ｋｇ，对照组４０只大鼠静注平衡液１ｍｌ／ｋｇ。结果：治疗组术后７ｄ存活率为６０％（１２／２０），而对照组为１５％（３／２０）；治疗组术后血清水平和再灌注后肝坏死范围明显低于对照组（Ｐ＜００５）。结论：肝保护液对大鼠肝常温缺血再灌注损伤具有明显的防治作用，这与减轻肝血窦阻力、增加肝血流，改善肝脏微循环障碍有关。     

锌对肝缺血再灌注损伤的对抗作用及其机制研究

目的:观察外源性锌对缺血再灌注肝脏(HIR)的防护作用并探讨其机制,包括对粘附分子表达的影响。方法:复制大鼠HIRI模型,灌胃给锌,观察实验动物肝组织形态、血清转氨酶活性、血清丙二醛(MDA)含量及粘附分子表达的改变。结果:在肝脏缺血30min,再灌注90min时,大鼠血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)活性增高,肝细胞结构受损,血清MDA含量升高,肝组织中细胞间粘附分子-1(ICAM-1)和血管细胞粘附分子-1(VCAM-1)两种粘附分子表达增强;锌+缺血再灌注组大鼠血清GPT、GOT活性及血清MDA含量均明显低于缺血再灌注组,肝组织粘附分子表达亦较弱,肝细胞的结构基本正常。结论:外源给锌可以明显减轻肝脏缺血再灌注损伤,抗脂质过氧化和抑制粘附分子表达是其作用的重要机制。     

缺血预处理通过抑制白三烯C4生成减轻大鼠肝缺血再灌注损伤

 目的：研究缺血预处理（IP）减轻大鼠肝脏缺血再灌注（I/R）损伤是否涉及前炎症因子白三烯C4(LTC4)。方法：健康成年雄性SD大鼠随机分为3组(每组6只)。I/R组： 采用大鼠部分（70%左右）肝脏缺血60 min再灌注5 h模型,缺血前15 min开始至复灌5 h经颈外静脉输注生理盐水（3 mL·kg-1·min-1）;假手术组：只麻醉开腹,不阻断肝脏血流;IP组：在I/R前先阻断肝左、中叶血流10 min,然后开放血流10 min,余步骤同I/R模型组。应用反相高效液相色谱法（RP-HPLC）检查肝组织LTC4含量,同时生化检测血清丙氨酸氨基转移酶（ALT）、天冬氨酸氨基转移酶（AST）活性和肝组织谷胱甘肽（GSH）含量,以及HE染色法检查肝组织学损伤。结果：肝脏IP处理完全逆转了再灌注5 h所致肝组织LTC4含量增加（P<0.05）;同时增加肝组织GSH含量,明显降低血清ALT和AST活性（P<0.05）,并减轻肝脏组织结构损伤。结论：IP处理减少肝脏I/R期间LTC4堆积,同时伴随血清肝酶释放减少和肝组织结构损伤降低,以及保护肝组织氧化还原状态,表明IP的有利影响可能涉及其在肝脏I/R损伤期间抑制LTC4生成。     

Mechanism of liver injury following ischemia.

To clarify whether ischemic liver injury is due to ischemia itself or reperfusion, histopathological and functional changes in the liver were examined before and after liver ischemia in rats with porto-systemic collateral channels. Effects of oxygen-derived free radical scavengers or an inhibitor of platelet aggregation on development of ischemic liver injury were also examined. Liver ischemia was produced by ligation of the portal vein and hepatic artery at liver hilum for 1 hr. The primary lesion of ischemic liver injury was cloudy swelling of liver cells in the periportal and midzonal regions; it developed during ischemia. The cloudy swelling of liver cells induced uneven distribution of sinusoidal blood flow after reperfusion, and consequently individual liver cell necrosis and focal hepatocellular necrosis in the midzonal regions developed later. Elevation of cytoplasmic enzyme activities in the serum after reperfusion was due to leakage across the damaged plasma membrane of liver cells. The treatment with superoxide dismutase, catalase, or heparin had not altered the liver injury that was attributed to ischemia, biochemically and histologically. These results suggest that ischemic liver injury is due to liver cell damage developed during ischemia, and that the ischemic liver injury is not alleviated or prevented by superoxide dismutase, catalase, or heparin.     

IL-13 Activates STAT6 and Inhibits Liver Injury Induced by Ischemia/Reperfusion

Hepatic ischemia/reperfusion injury is initiated by the activation of Kupffer cells and their subsequent release of proinflammatory mediators, including tumor necrosis factor-alpha (TNFalpha). These mediators stimulate a cascade of events including up-regulation of CXC chemokines and vascular endothelial adhesion molecules, leading to hepatic neutrophil recruitment and tissue injury. Interleukin-13 (IL-13) is a cytokine that has been shown to suppress macrophage production of proinflammatory mediators. The objective of the current study was to determine whether IL-13 could regulate the liver inflammatory injury induced by ischemia and reperfusion. C57BL/6 mice underwent 90 minutes of partial hepatic ischemia followed by reperfusion with or without intravenous administration of recombinant murine IL-13. Hepatic ischemia/reperfusion increased expression of TNFalpha and macrophage inflammatory protein-2 (MIP-2), leading to hepatic neutrophil recruitment, hepatocellular injury, and liver edema. Administration of IL-13 reduced the production of TNFalpha and MIP-2 mRNA and protein. IL-13 suppressed liver neutrophil recruitment by up to 72% and hepatocellular injury and liver edema were each reduced by >60%. Administration of IL-13 had no effect on liver NFkappaB activation, but greatly increased the activation of STAT6. The data suggest that the hepatoprotective effects of IL-13 may be a result of STAT6 activation.     

Hepatic microcirculatory perfusion failure is a determinant of liver dysfunction in warm ischemia-reperfusion.

Hepatic ischemia-reperfusion (I/R) is characterized by circulatory and metabolic derangements, liver dysfunction, and tissue damage. However, little is known about the causative role of I/R-induced microcirculatory disturbance on the manifestation of postischemic reperfusion injury. Therefore, the intention of the study was to assess changes of hepatic microvascular perfusion (intravital fluorescence microscopy) as related to hepatic morphology (light/electron microscopy), hepatocellular integrity (serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities), and excretory function (bile flow). Sprague-Dawley rats were subjected to 20 minutes (group B, n = 9) and 60 minutes (group C, n = 9) of left hepatic lobar ischemia followed by 60 minutes of reperfusion. Sham-operated animals without ischemia served as controls (group A, n = 10). Lobar ischemia for 20 minutes followed by reperfusion resulted in a significant reduction of sinusoidal perfusion rate (93.9 +/- 1.4%; P < 0.05) and a decrease in erythrocyte flux (90.0 +/- 5.6%) when compared with controls (99.4 +/- 0.2 and 97.9 +/- 2.7%). This was accompanied by a significant increase of serum AST and ALT activities (P < 0.05) and a reduction of bile flow (P < 0.05). Prolongation of lobar ischemia (group C, 60 minutes) aggravated postischemic reperfusion injury (sinusoidal perfusion rate: 87.4 +/- 2.9%; erythrocyte flux: 62.1 +/- 8.4%) and was paralleled by severed hepatocellular damage. Electron microscopy of postischemic tissue demonstrated alteration of nonparenchymal cells (swelling of sinusoidal lining cells and widening of Disse's space) and substantial parenchymal cell damage (swelling of mitochondria, disarrangement of rough endoplasmatic reticulum, vacuolization, complete cytoplasmic degeneration). Initial postischemic increase in serum AST and ALT activities and reduction of bile flow directly correlated with the extent of microcirculatory failure (P < 0.01), ie, impairment of sinusoidal perfusion and decrease of erythrocyte flux, indicating the decisive role of microvascular perfusion failure for the manifestation of hepatic tissue damage and liver dysfunction.     

缺血-再灌注肝脏组织中ICAM-1基因的表达

目的：探讨肝脏缺血-再灌注过程中肝窦内皮细胞ICAM-1 mRNA的表达规律及其意义。方法：应用分子杂交技术,观察缺血时间分别15、30及45 min的3组兔肝脏于再灌注60 min时ICAM-1 mRNA的表达情况,并对肝窦腔内的白细胞数量进行计数。结果：3组肝脏缺血前及缺血末组织内仅有少量ICAM-1 mRNA表达于肝窦内皮细胞浆内,且肝窦腔内的白细胞数量也无明显改变;但于再灌注60 min时,ICAM-1 mRNA表达程度则显著增强,且缺血时间越长的肝脏,其表达强度越大。此外,组织内ICAM-1 mRNA含量越高的肝脏,肝窦腔内白细胞数量越多,两者呈显著的正相关关系。结论：肝脏的缺血能明显诱导再灌注期间肝窦内皮细胞表达ICAM-1,增强肝窦内皮细胞的粘附力,促进再灌注血流中的白细胞在肝窦内滞留,进而引发一系列病理生理改变。     

Bioelectrical Impedance May Predict Cell Viability During Ischemia and Reperfusion in Rat Liver

Ischemia and reperfusion (I/R) injury is a major cause of hepatic failure after liver surgery, but no method could monitor or predict it real-time during surgery. We measured bioelectrical impedance (BEI) and cell viability to assess the usefulness of BEI during I/R in rat liver. A 70% partial liver ischemia model was used. BEI was measured at various frequencies. Adenosine triphosphate (ATP) content, and palmitic acid oxidation rate were measured, and histological changes were observed in order to quantify liver cell viability. BEI changed significantly during ischemia at low frequency. In the ischemia group, BEI increased gradually during 60 min of ischemia and had a tendency to plateau thereafter. The ATP content decreased below 20% of the baseline level. In the I/R group, BEI recovered to near baseline level. After 24 hr of reperfusion, the ATP contents decreased to below 50% in 30, 60 and 120 min of ischemia and the palmitic acid metabolic rates decreased to 91%, 78%, and 74%, respectively, compared with normal liver. BEI may be a good tool for monitoring I/R during liver surgery. The liver is relatively tolerant to ischemia, however after reperfusion, liver cells may be damaged depending upon the duration of ischemia.     

IL-8单抗保护兔肝脏免受中性粒细胞介导的再灌注损伤

通过建立新西兰家兔的肝缺血再灌注损伤模型 ,观察抗IL 8中和性单克隆抗体对缺血再灌注 (IR )损伤肝脏的保护作用。肝缺血再灌注 4h后 ,外周血中各种肝功能指标酶活性与假手术组相比显著升高 (P <0 0 5 ) ,同时肝脏出现大量散点状中性粒细胞的浸润 ,此时肝细胞明显肿胀 ,细胞呈散乱状排列 ,细胞壁结构不完整并出现液化现象。而使用抗IL 8抗体后可明显阻断再灌注过程中中性粒细胞对肝脏的浸润 ,肝细胞虽仍有肿胀现象 ,但细胞呈正常的规则排列 ,细胞壁结构完整。其外周血肝功能指标酶活性与对照组相比无显著差别。该结果显示在肝再灌注损伤过程中 ,IL 8是趋化中性粒细胞浸润的关键因子 ,抗IL 8单克隆抗体对肝缺血再灌损伤肝脏有保护作用。     

HMGB1 translocation and expression is caused by warm ischemia reperfusion injury, but not by partial hepatectomy in rats

Mechanical injury or ischemia/reperfusion (I/R) injury induces high mobility of group box 1 (HMGB1) translocation and release. However, the surgical procedure itself can initiate pathophysiologic processes causing damage to the respective organ. A liver resection, as an example, leads to portal hyperperfusion injury of the remnant liver. Therefore, we aimed to elucidate the impact of different hepatic surgical injury models on cellular localization and expression of HMGB1. Focal warm I/R injury was induced by clamping the vascular blood supply to the median and left lateral liver lobes for 90 min followed by 0.5 h, 6 h and 24 h reperfusion, as reported previously. Liver injury by PH was induced by subjecting rats to 30%, 70% or 90% partial hepatectomy (PH) followed by a 24 h observation period. Additional 12 rats were subjected to 90% PH and sacrificed at 1 h and 6 h to investigate the expression and release pattern of HMGB1. Elevation of serum liver enzymes indicating hepatic injury peaked at 6 h and recovered thereafter in models, warm I/R injury and PH. Liver injury was confirmed by liver histology. HMGB1 was translocated from the nucleus to the cytoplasm in livers subjected to warm I/R; but not in livers subjected to PH. Both protein and mRNA expression of HMGB1 were significantly up-regulated in livers subjected to warm I/R. In contrast, neither 30% PH, 70% PH nor 90% PH caused an elevation of hepatic HMGB1 mRNA and protein expression. High serum levels of HMGB1 (30 ng/ml) were measured at 0.5 h reperfusion period after warm I/R, much lower levels thereafter (< 5 ng/ml). Similar low serum levels were measured at all time points after 90% PH. Subsequently expression levels of TNF-a should be changed to tumor necrosis factor-alpha (TNF-α) reached a peak (26-fold elevation) at 6 h and decreased down to 5-fold at 24 h after warm I/R. TNF-α expression levels after PH never exceeded a 5-fold elevation. In conclusion, HMGB1 translocation and expression depends on the type of liver injury as it is induced by ischemia, but not by liver resection/hyperperfusion. These results suggest that HMGB1 may be used as molecular marker to visualize ischemic damage. Mechanic injury in hepatic surgery is associated with focal warm ischemia, and thereby HMGB1 translocation reflects surgical quality in experimental PH. Expression of hepatic TNF-α follows the kinetic pattern of HMGB1, pointing to a muss less pronounced inflammatory response after successful PH compared to warm I/R injury.