肝缺血再灌注损伤对肿瘤增殖、转移的影响

肝缺血再灌注损伤(hepatic ischemia/reperfusion injury,HIRI)是肝脏外科常见的病理生理过程.HIRl通过引起趋化因子、黏附分子、基质金属蛋白酶、血管内皮细胞生长因子等细胞因子表达改变,对血液中残留肿瘤细胞的迁移、黏附、定植、生长等步骤有着重要的影响.与肝癌术后的复发、转移关系密切.     

Requirement for interleukin-12 in the pathogenesis of warm hepatic ischemia/reperfusion injury in mice

Hepatic ischemia and reperfusion causes neutrophil-dependent liver injury. Although the mechanisms of ischemia/reperfusion-induced liver neutrophil recruitment are somewhat understood, less is known regarding the early events that initiate the inflammatory injury. Using a murine model of partial hepatic ischemia and reperfusion, we evaluated the role of endogenous interleukin (IL)-12 in this inflammatory response. Hepatic ischemia for 90 minutes and reperfusion for up to 4 hours resulted in hepatocyte expression of IL-12. By 8 hours of reperfusion there were large increases in serum levels of interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha). In addition, hepatic ischemia/reperfusion caused significant increases in liver neutrophil recruitment, hepatocellular injury, and liver edema, as defined by liver myeloperoxidase content, serum alanine aminotransferase, and liver wet to dry weight ratios, respectively. In mice treated with neutralizing antibody to IL-12 and in mice deficient in the IL-12 p40 gene, ischemia/reperfusion-induced increases in IFNgamma and TNFalpha were greatly diminished. These conditions also caused significant reductions in liver myeloperoxidase content and attenuated the parameters of liver injury. The data suggest that IL-12 is required for the full induction of injury after hepatic ischemia and reperfusion.     

Effects of Wy14643 on hepatic ischemia reperfusion injury in rats

AIM： To investigate the effects and possible mechanisms of Wy14643 on hepatic ischemiareperfusion （I/R） injury in rats. METHODS： Thirty male Sprague-Dawley rats weighing 220-280 g were randomly divided into five experimental groups： sham group （G1, n = 6）： a sham operation was performed （except for liver I/R）, I/R-untreated group （G2, n = 6）： rats underwent liver ischemia for 90 min followed by reperfusion for 4h; and I/R ＋ Wy14643 groups （G3, G4, G5; n = 6）： after the same surgical procedure as in group 2, animals were pretreated with Wy14643 at the dose of 1, 5 and 10 mg/kg 1 h before ischemia, respectively. Hepatic ischemia-reperfusion （I/R） was induced by clamping blood supply to the left lateral and median lobes of the liver for 90 min, and atraumatic clamp was removed for 4 h reperfusion. Blood samples and liver tissues were obtained at the end of reperfusion to assess serum and hepatic tissue homogenate aminotransferase （ALT）, aspartate aminotransferase （AST）, myeloperoxidase （MPO）, serum interleukin- 1β（IL-1β） and tumor necrosis factor alpha （TNF-α）, as well as activity of superoxide dismutase （SOD） and content of malondialdehyde （MDA） in the hepatic tissue homogenate. RESULTS： Hepatic I/R induced a significant increase in the serum levels of ALT, AST, TNF-α, IL-1β and MPO, as well as the levels of ALT, AST and MDA in the liver tissue homogenate, which were reduced by pretreatment with Wy14643 at the dose of 1, 5 and 10 mg/kg, respectively. The activity of SOD in the liver tissue homogenate was decreased after hepatic I/R, which was enhanced by Wy14643 pretreatment. In addition, serum and liver tissue homogenate ALT and AST in the Wy14643 10 mg/kg group were lower than in the Wy14643 1 mg/kg and 5 mg/kg groups, respectively. CONCLUSION： Wy14643 pretreatment exerts significant protection against hepatic I/R injury in rats. The protective effects are possibly associated with enhancement of anti-oxidant and inhibition inflammation res     

JNK mediates hepatic ischemia reperfusion injury

BACKGROUND/AIMS: Hepatic ischemia followed by reperfusion (I/R) is a major clinical problem during transplantation, liver resection for tumor, and circulatory shock, producing apoptosis and necrosis. Although several intracellular signal molecules are induced following I/R including NF-kappaB and c-Jun N terminal kinase (JNK), their roles in I/R injury are largely unknown. The aim of this study is to assess the role of JNK during warm I/R injury using novel selective JNK inhibitors. METHODS: Male Wistar rats (200+/-25 g) are pretreated with vehicle or with one of three compounds (CC0209766, CC0223105, and CC-401), which are reversible, highly selective, ATP-competitive inhibitors of JNK. In the first study, rats are assessed for survival using a model of ischemia to 70% of the liver for 90 min followed by 30% hepatectomy of the non-ischemic lobes and then reperfusion. In the second study, rats are assessed for liver injury resulting from 60 or 90 min of ischemia followed by reperfusion with analysis over time of hepatic histology, serum ALT, hepatic caspase-3 activation, cytochrome c release, and lipid peroxidation. RESULTS: In the I/R survival model, vehicle-treated rats have a 7-day survival of 20-40%, while rats treated with the three different JNK inhibitors have survival rates of 60-100% (P<0.05). The decrease in mortality correlates with improved hepatic histology and serum ALT levels. Vehicle treated rats have pericentral necrosis, neutrophil infiltration, and some apoptosis in both hepatocytes and sinusoidal endothelial cells, while JNK inhibitors significantly decrease both types of cell death. JNK inhibitors decrease caspase-3 activation, cytochrome c release from mitochondria, and lipid peroxidation. JNK inhibition transiently blocks phosphorylation of c-Jun at an early time point after reperfusion, and AP-1 activation is also substantially blocked. JNK inhibition blocks the upregulation of the pro-apoptotic Bak protein and the degradation of Bid. CONCLUSIONS: Thus, JNK inhibitors decrease both necrosis and apoptosis, suggesting that JNK activity induces cell death by both pathways.     

Ascorbate inhibits apoptosis of Kupffer cells during warm ischemia/reperfusion injury

BACKGROUND/AIMS: This study sought to determine whether ascorbate (Asc), a scavenger of reactive oxygen species, inhibits apoptosis of hepatic cells consisting of hepatocytes, Kupffer cells, and sinusoidal endothelial cells (SECs) in the rat liver after warm ischemia/reperfusion (I/R) injury. METHODOLOGY: Hepatic warm ischemia (69% of the total liver) was induced for 30 min, followed by reperfusion for 60 min. In some animals, ascorbate (at 1 or 10 mg/kg) was infused intravenously immediately before the onset of reperfusion. Hepatic cell apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). Mitochondrial release of cytochrome c into the cytoplasm was assessed by Western blot analysis, and the activation of caspase-3 in liver tissue was determined by colorimetric assays. RESULTS: Assays of cytochrome c release and caspase-3 showed increased levels of these apoptotic related proteins and enzyme activity. While few apoptotic hepatocytes or SECs were detected in the ischemic group by TUNEL staining, the number of TUNEL-positive Kupffer cells was approximately 4.5-fold greater than that seen in the sham-treatment group. Ascorbate treatment reduced this increase in apoptotic Kupffer cells. CONCLUSION: The hepatic cells most vulnerable to oxidative stress in the first hour of reperfusion were Kupffer cells. These may play a key role in hepatic warm I/R injury.     

Inhibitory effects of safe and novel SOD derivatives, galactosylated-SOD, on hepatic warm ischemia/reperfusion injury in pigs

BACKGROUND/AIMS: Oxygen-derived free radicals such as superoxide play an important role in ischemia/reperfusion (IR) injury during and after extensive liver surgery or liver transplantation. Superoxide dismutase (SOD) has protective effects against hepatic IR injury. The effect of native SOD is, however, limited because of rapid elimination from the blood circulation and poor affinity for liver cells. It was reported by our collaborators that a SOD derivative modified with galactose (Gal-SOD) was selectively delivered well to hepatocytes by direct attachment to galactose receptors. In the present study, the efficacy of this agent for attenuating hepatic warm IR injury was investigated using the pig model. METHODOLOGY: After 45-min clamping of the hepatic artery and portal vein, pigs were divided into 3 groups according to the following treatments. Ten milliliters of normal saline in Group 1 (n=5), 10,000 units/kg of native SOD in Group 2 (n=5) and 10,000 units/kg of Gal-SOD in Group 3 (n=5) were given just prior to hepatic reperfusion. Liver function including clearance of total bile acid (TBA) and hyaluronic acid (HA) was investigated. Lipid peroxidase of the liver tissue (LPO) and histological findings were examined. In addition, survival rates of the pigs in each group were evaluated. RESULTS: The survival rates at the 7th day after the operation were 60%, 80%, 100% in Groups 1, 2 and 3, respectively. Liver function tests, clearance of TBA and HA, and LPO levels were significantly improved in Groups 3 over findings in Groups 1 and 2. Congestion of hepatic tissues and vacuolization of hepatocytes in Group 3 were less than those in Groups 1 and 2. These results suggested that oxygen-derived free radicals were scavenged by Gal-SOD and IR injury was attenuated. CONCLUSIONS: A safe and novel agent, Gal-SOD has a protective effect against hepatic warm IR injury.     

Apoptosis versus oncotic necrosis in hepatic ischemia/reperfusion injury

Warm and cold hepatic ischemia followed by reperfusion leads to necrotic cell death (oncosis), which often occurs within minutes of reperfusion. Recent studies also suggest a large component of apoptosis after ischemia/reperfusion. Here, we review the mechanisms underlying adenosine triphosphate depletion-dependent oncotic necrosis and caspase-dependent apoptosis, with emphasis on shared features and pathways. Although apoptosis causes internucleosomal DNA degradation that can be detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling and related assays, DNA degradation also occurs after oncotic necrosis and leads to pervasive terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining far in excess of that for apoptosis. Similarly, although apoptosis can occur in a physiological setting without inflammation, in pathophysiological settings apoptosis frequently induces inflammation because of the onset of secondary necrosis and stimulation of cytokine and chemokine formation. In liver, the mitochondrial permeability transition represents a shared pathway that leads to both oncotic necrosis and apoptosis. When the mitochondrial permeability transition causes severe adenosine triphosphate depletion, plasma membrane failure and necrosis ensue. If adenosine triphosphate is preserved, at least in part, cytochrome c release after the mitochondrial permeability transition activates caspase-dependent apoptosis. Mitochondrial permeability transition-dependent cell death illustrates the concept of necrapoptosis, whereby common pathways lead to both necrosis and apoptosis. In conclusion, oncotic necrosis and apoptosis can share features and mechanisms, which sometimes makes discrimination between the 2 forms of cell death difficult. However, elucidation of critical cell death pathways under clinically relevant conditions will show potentially important therapeutic intervention strategies in hepatic ischemia/reperfusion injury.     

Conjugated desferoxamine attenuates hepatic microvascular injury following ischemia/reperfusion

Iron-dependent oxy radicals have been implicated in reperfusion injury. Although the iron chelator desferoxamine (DFO) is beneficial, its hemodynamic effects and short vascular retention limit its use in vivo. We tested whether DFO conjugated to a high-molecular-weight starch might ameliorate in vivo hepatic microvascular injury without adverse side effects following 120 min of ischemia. Prior to reperfusion, conjugated DFO (100 mg/kg), vehicle (Veh), or saline (I/R) was administered. After 90 min of reperfusion, blood was collected for serum transaminase determination (ALT; U/liter), and fluorescein-albumin was injected to label perfused microvessels, which were quantified in frozen sections by a point-count technique. Tissue edema was estimated by wet to dry weight ratios (W/D). Reperfusion results in hepatocyte injury (rise in ALT and W/D) and a 30% loss of perfused microvessels. Intravenous administration of conjugated DFO produces no significant change in systemic hemodynamics, whereas both ALT and tissue edema were decreased by approximately 50%. Moreover, perfused microvessels were restored virtually to nonischemic control levels. Enhanced perfusion and attenuated cell injury with DFO suggest that microvascular failure and resultant cell death are mediated, at least in part, by iron-dependent mechanisms in reperfusion.     

Metalloproteinase-9 deficiency protects against hepatic ischemia/reperfusion injury

Leukocyte transmigration across endothelial and extracellular matrix protein barriers is dependent on adhesion and focal matrix degradation events. In the present study we investigated the role of metalloproteinase-9 (MMP-9/gelatinase B) in liver ischemia/reperfusion (I/R) injury using MMP-9-deficient (MMP-9(-/-)) animals and mice treated with a specific anti-MMP-9 neutralizing antibody or with a broad gelatinase inhibitor for both MMP-9 and metalloproteinase-2 (MMP-2/gelatinase A). Compared to wild-type mice, MMP-9(-/-) mice and mice treated with an anti-MMP-9 antibody showed significantly reduced liver damage. In contrast, mice treated with a broad gelatinase inhibitor showed rather inferior protection against I/R injury and were characterized by persistent ongoing liver inflammation, suggesting that MMP-2 and MMP-9 may have distinct roles in this type of injury. MMP-9 was mostly detected in Ly-6G and macrophage antigen-1 leukocytes adherent to the vessel walls and infiltrating the damaged livers of wild-type mice after liver I/R injury. Leukocyte traffic and cytokine expression were markedly impaired in livers of MMP-9(-/-) animals and in livers of mice treated with anti-MMP-9 antibody after I/R injury; however, initiation of the endothelial adhesion cascades was similar in both MMP-9(-/-) and control livers. We also showed that MMP-9-specific inhibition disrupted neutrophil migration across fibronectin in transwell filters and depressed myeloperoxidase (MPO) activation in vitro. CONCLUSION: These results support critical functions for MMP-9 in leukocyte recruitment and activation leading to liver damage. Moreover, they provide the rationale for identifying inhibitors to specifically target MMP-9 in vivo as a potential therapeutic approach in liver I/R injury.     

Redox therapeutics in hepatic ischemia reperfusion injury

Ischemia-reperfusion plays a major role in the injury experienced by the liver during transplantation. Much work has been done recently investigating the role of redox species in hepatic ischemia-reperfusion. As animal models are better characterized and developed, and more insights are gained into the pathophysiology of hepatic ischemia reperfusion injury in humans the questions into exactly how oxidants participate in this injury are becoming more refined. These questions include effects of cellular location, timing of injury, and ability of therapeutics to access this site are increasing our appreciation of the complexity of ischemia reperfusion and improving attempts to ameliorate its effects. In this review, we aim to discuss the various methods to alter redox chemistry during ischemia reperfusion injury and future prospects for preventing organ injury during hepatic ischemia reperfusion.     

Redox therapeutics in hepatic ischemia reperfusion injury简

Ischemia-reperfusion plays a major role in the injury experienced by the liver during transplantation. Much work has been done recently investigating the role of redox species in hepatic ischemia-reperfusion. As animal models are better characterized and developed, and more insights are gained into the pathophysiology of hepatic ischemia reperfusion injury in humans the questions into exactly how oxidants participate in this injury are becoming more refined. These questions include effects of cellular location, timing of injury, and ability of therapeutics to access this site are increasing our appreciation of the complexity of ischemia reperfusion and improving attempts to ameliorate its effects. In this review, we aim to discuss the various methods to alter redox chemistry during ischemia reperfusion injury and future prospects for preventing organ injury during hepatic ischemia reperfusion.     

Mechanisms of reperfusion injury after warm ischemia of the liver

The review highlights recent advances in our understanding of basic mechanisms of reperfusion injury after warm hepatic ischemia. Kupffer cells play a central role as the initial cytotoxic cell type and as a source of many proinflammatory mediators. Subsequently, neutrophils are activated and recruited into the liver. Factors and conditions are outlined that determine whether neutrophils undergo apoptosis without causing damage or migrate out of the sinusoids and attack parenchymal cells. In addition to the inevitable inflammatory response during reperfusion, microcirculatory perfusion failure, due to an imbalance between the actions of vasodilators and vasoconstrictors, also has a serious impact on reperfusion injury. A better understanding of the basic pathophysiology will reveal potential targets for therapeutic interventions and will show us how to avoid risk factors that may aggravate reperfusion injury.     

Splenectomy-reduced hepatic injury induced by ischemia/reperfusion in the rat

Abstract: In the present study, we investigated the role of the spleen in experimental hepatic ischemia/reperfusion in the rat. After a 90-min period of ischemia in the left and middle hepatic lobes, the ischemia was released and the liver was reperfused for up to 24 h. Plasma alanine aminotransferase reached a peak 3 h after the onset of reperfusion, and gradually decreased thereafter. A histological examination revealed evidence of hepatocellular necrosis and degeneration, especially 24 h after the onset of reperfusion. In addition, there was a noticeable accumulation of polymorphonuclear cells in the liver following ischemia/reperfusion. A splenectomy performed just prior to ischemia/reperfusion reduced both biochemical and histological hepatocellular injury. The number of polymorphonuclear cells in the liver following ischemia/reperfusion was significantly reduced in rats subjected to splenectomy, suggesting that the increase in polymorphonuclear cells may contribute to liver injury. The number of mononuclear cells also increased in the marginal zones of the spleen following ischemia/reperfusion, and appeared to be derived from the splenic monocyte/macrophage population, based on immunohistochemical studies. The spleen plays an important role in the pathogenesis of hepatic ischemia/reperfusion injury and the splenic monocyte/macrophage population contributes to liver damage.     

Effect of N—desulfated heparin on hepatic／renal ischemia reperfusion injury in rats

AIM：To invesigate the effect of N-desulfated heparin on hepatic/renal ischemia and reperfusion injury in rats.METHODS:Using rat models of 60minutes hepatic of renal ischemia followed by 1h,3h,6hand24h reperfusion.animals were randomly divided into following groups,the sham operated controls,ischemic group receiving only normal saline,and treated group receiving N-desulfated heparin at a dose of 12mg/kg at 5minutes before reperfusion.P-selectin expression was detected in hepatic/renal tissues with immunohistochemistry method.RESULTS:P-selectin expression,serumALT,AST,BUNand Cr levels were significantly increased during60minute ischemia and 1h,3h,6hand24hreperfusion.while the increment was significantly inhibited,and hepatic/renal pathology observed by light microscopy was remarkably improved by treatment with the N-desulfated heparin.Furthermore.the heparin was found no effects on PT and KPTT.CONCLUSION:P-selectin might mediate neutrophil infitration and contribute to hepatic/renai ischemia and reperfusion.THe N-desulfated heparin might prevent hepatic/renal admage induced by ischemia and reperfusion injury without significant anticoagulant activity.     

缺血期急性高血糖对大鼠心肌缺血/再灌注损伤的影响

目的 探讨缺血期急性高血糖对大鼠心肌缺血/再灌注(MI/R)后心肌损伤的影响,并分析血糖水平与心肌损伤之间的关系.方法 在制备急性大鼠MI/R(缺血30min,再灌注6h)模型的基础上,静脉输注高浓度的葡萄糖溶液,造成2个不同浓度的缺血期急性高血糖动物模型.将32只SD大鼠随机平均分配为4组:(1)假手术组(SHAM),(2)生理盐水对照组(CON),(3)高糖1组(HG1)和(4)高糖2组(HG2).术中监测血糖水平,再灌注结束后检测心肌酶谱水平和心肌梗死面积(IS).结果 (1)与CON组相比较,HG1组和HG2组缺血期血糖水平均显著升高,分别为(10.5±1.0)、(18.0±1.2)mmol/L vs(4.7±0.7)mmol/L(P<0.05).(2)HG1组和HG2组的血肌酸激酶和乳酸脱氢酶水平明显升高,且心肌酶谱与血糖水平存在正相关(r分别为0.80和0.73,P<0.01).(3)HG1组的IS较CON组有扩大趋势,但差异无统计学意义[(40.8±5.2)%vs(37.6±5.8)%,P>0.05),HG2组的IS明显扩大[(45.6±8.5)%v8(37.6±5.8)%,P<0.05],且IS与血糖水平存在正相关(r=0.57,P<0.01).结论 缺血期急性高血糖加重大鼠MI/R损伤,且血糖水平与心肌酶谱和IS之间存在正相关.     

心肌缺血再灌注损伤研究进展

急性心肌梗死是主要的致死致残原因,再灌注治疗是其标准的治疗方案,然而再灌注治疗伴随着再灌注损伤,再灌注损伤的机理目前还未完全清楚,分子、细胞、组织上的改变均与参与再灌注损伤,本文就心肌缺血再灌注损伤的研究进展作一综述。