肝脏非实质细胞在脂质代谢中的作用

肝细胞在脂质代谢中的作用已有较多的论述,近来发现肝非实质细胞包括肝星状细胞,枯否细胞,窦内皮细胞,Ｐｉｔ细胞与脂质代谢也有密切的关系。本综术了近年来肝非实质细胞在脂质代谢中的作用。     

肝脏非实质细胞在脂质代谢中的作用

肝细胞在脂质代谢中的作用已有较多的论述,近来发现肝非实质细胞包括肝星状细胞、枯否细胞、窦内皮细胞、Pit细胞与脂质代谢也有密切的关系。本文综述了近年来肝非实质细胞在脂质代谢中的作用。     

肝脏缺血再灌注损伤机制及干预的研究进展

肝脏缺血再灌注损伤(HIRI)是一个多因素共同作用的过程,在一定程度上制约了肝脏外科的发展。深入研究HIRI的机制,制订合理的干预治疗策略,对提高患者预后起着积极的作用。介绍了HIRI的相关发生机制,主要涉及钙超载、Kupffer细胞、微循环障碍、活性氧的产生、补体、非编码RNA以及各种细胞因子等多种因素,各个因素共同作用,导致肝细胞的坏死、凋亡。此外,自噬作为第二类细胞死亡方式,也参与了HIRI。鉴于HIRI的机制复杂,涉及因素众多,需从多方面着手干预。指出随着缺血预处理、亚低温以及氢气等干预方法的出现,新型的治疗方法有望为临床干预HIRI治疗带来新的思路。     

肝窦内皮细胞在肝脏缺血再灌注损伤中的作用

肝脏缺血再灌注损伤是肝移植术后供肝原发性无功能的主要原因，而肝窦内皮细胞由于其所处的特殊解剖位置和生理特点，在缺血再灌注损伤的病理生理过程中发挥着重要作用。本从再灌注后活性氧的产生、白细胞的粘附迁移、血管活性因子的释放等方面阐述肝窦内皮细胞在肝脏缺血再灌注损伤中的作用，并对如何防治展开初步探讨。     

沉默信息调节因子1在肝脏缺血再灌注损伤中的作用

肝脏缺血再灌注损伤一直是肝移植及肝脏肿瘤切除等手术中面临的难题,多种机制的参与使其变得尤为复杂,其中缺血期间的能量消耗和再灌注诱导的氧化应激是导致肝脏缺血再灌注损伤的主要机制,二者共同导致细胞死亡甚至引发肝衰竭。沉默信息调节因子(Sirt)是一类具有烟酰胺腺嘌呤二核苷酸依赖性的脱乙酰化酶,可使组蛋白及非组蛋白等转录因子脱乙酰化,在细胞凋亡、炎症反应、能量平衡及氧化应激等方面发挥重要的调节作用,哺乳动物体内沉默信息调节因子有7种,包括Sirt1～Sirt7,其中,Sirt1可通过多种信号通路来减轻肝细胞应激并调控细胞代谢途径,从而达到减轻肝脏缺血再灌注损伤程度的目的,主要对Sirt1相关信号通路在肝脏缺血再灌注损伤中的作用进行了综述。     

肝窦内皮细胞在肝脏缺血再灌注损伤中的作用

肝脏缺血再灌注损伤是肝移植术后供肝原发性无功能的主要原因,而肝窦内皮细胞由于其所处的特殊解剖位置和生理特点,在缺血再灌注损伤的病理生理过程中发挥着重要作用。本文从再灌注后活性氧的产生、白细胞的粘附迁移、血管活性因子的释放等方面阐述肝窦内皮细胞在肝脏缺血再灌注损伤中的作用,并对如何防治展开初步探讨。     

肝移植缺血再灌注损伤与细胞粘附分子

自本世纪80年代以来,伴随着手术技巧的提高、新型免疫抑制剂和UW保存液的相继问世,临床肝移植取得了长足的进步。然而,缺血再灌注损伤依然是困扰着肝移植的研究难点,它是引发术后原发性移植物无功能(primary graftnonfunction)的重要原因。而随着近年来对细胞粘附分子研究的不断深入,表明细胞粘附分子恰恰参与并介导了缺血再灌注损伤过程中的各个步骤。本文综述近年来在此领域的研究进展。 一、细胞粘附分子的种类、结构与功能 细胞粘附分子分布极其广泛,涉及生命活动的许多现象,包括细胞分裂、分化以及细胞凋亡的调控等等。根据结构与功能,粘附分子可初步分为5类,即整合素家族、免疫球蛋白超家族、选择素家族、钙粘附蛋白家族和其它粘附分子。前三者是参与肝移植过程中缺血再灌注等炎症反应和免疫应答的重要家族。     

CDc25c在肝脏缺血再灌注损伤中的保护作用

目的探讨Cdc25c对肝脏缺血再灌注半脘氨酸蛋白酶(Caspase)-3蛋白表达的影响及与肝细胞凋亡的内在联系。方法健康30只SD大鼠随机分为空白对照组(S组);缺血再灌注+生理盐水组(I/R组);pAdEasy-Cdc25c+缺血再灌注组(C组),每组10只。Western印迹方法检测CDc25c、Caspase-3在肝脏组织中的表达;TUNEL法检测肝细胞凋亡。结果 I/R组中Caspase-3的蛋白表达及肝细胞凋亡明显多于S组(P<0.05);S和C组中Cdc25c的蛋白表达高于I/R组,而细胞凋亡低于I/R组(P<0.05)。结论 Cdc25c的表达降低Caspase-3蛋白的表达,抑制肝细胞凋亡,保护缺血再灌注肝损伤。     

肝血窦在内毒素致肝损伤中的作用

内毒素是革兰阴性菌细胞壁中的特有成分,又称脂多糖(LPS)。肝脏既是清除细菌和内毒素的场所,又是最易受损的器官。肝损伤最初发生在肝血窦。主要介绍了LPS对Kupffer细胞、肝窦内皮细胞、肝血窦中氧化/抗氧化平衡及肝脏血流的影响。认为肝血窦在LPS所造成的肝损伤中的作用不容忽视,研究其对防治LPS致肝损伤有重要意义。     

Glycine maintains mitochondrial activity and bile composition following warm liver ischemia-reperfusion injury

Background and Aim: Experimental studies have shown protective effect by the non‐essential amino acid glycine to liver ischemia‐reperfusion (I/R) injury but the mechanism of action is unknown. Methods: A rabbit model of hepatic lobar I/R was used. Three groups of animals (n = 6) were studied: Sham group (laparotomy alone), ischemia reperfusion (I/R) group (1 h of liver lobar ischemia and 6 h of reperfusion), and a glycine I/R group (intravenous glycine 5 mg/kg prior to the I/R protocol). Systemic and hepatic hemodynamics, degree of liver injury (bile flow, transaminases), hepatic microcirculation, mitochondrial activity (redox state of cytochrome oxidase), bile composition and cytokines (tumor necrosis factor‐α and interleukin‐8) were measured during the experiment. Results: Glycine administration increased portal blood flow, bile production, hepatic microcirculation and maintained cytochrome oxidase activity as compared with the I/R group during reperfusion. Glycine also reduced bile lactate surge and stimulated acetoacetate release in bile during reperfusion versus the I/R group. Cytokine levels (tumor necrosis factor‐α, interleukin‐8) and hepatocellular injury (aspartate aminotransferase and alanine aminotransferase) were significantly reduced by glycine administration. Conclusion: Intravenous glycine administration reduces liver warm I/R injury by reducing the systemic inflammatory response, and maintaining cellular energy production.     

库普弗细胞在内毒素血症致肝损伤中的作用

内毒素血症是导致肝损伤的一个重要因素。近年来研究证实,内毒素血症所致肝损伤与内毒素(LPS)引起库普弗细胞的过度活化密切相关,LPS导致库普弗细胞合成及分泌大量炎症介质和细胞因子,从而导致肝损伤。现就库普弗细胞在内毒素血症所致肝损伤中的作用作一综述。     

Neutrophil-mediated liver injury during hepatic ischemia-reperfusion in rats

BACKGROUND: Neutrophil plays an important role in hepatic ischemia-reperfusion injury. We investigated neutrophil infiltration in liver tissue, Kupffer cells' role in neutrophil accumulation, and apoptosis and regeneration of hepatocytes in liver ischemia-reperfusion injury. METHODS: Vascular microclamps were placed across the pedicles of the median and left lateral lobes for 90 minutes after 30% hepatectomy with the resection of caudate, right lateral and quadrate lobes and papillary process. Gadolinium chloride (GdCl3) was used to destroy Kupffer cells. Neutrophil activity was inhibited with Urge-8, a monoclonal antibody against neutrophil produced in our laboratory. GdCl3 (10 mg/kg) and Urge-8 (50 mg/kg) were given intravenously in respective groups. Ischemia control, GdCl3 and Urge-8 groups were compared. RESULTS: Following hepatic reperfusion, serum interleukin-8 (IL-8) levels and hepatic neutrophil counts peaked at 3 hours, and peak concentrations of alanine aminotransferase (ALT) occurred at 6 hours. Animals of the control group showed increases in neutrophil infiltration in liver tissue, liver enzyme levels, and apoptosis index of hepatocytes and decreases in overall survival rate and proliferating cell nuclear antigen (PCNA) expression of hepatocytes. The survival rates and PCNA proportion of hepatocytes were higher and the levels of hepatic neutrophil infiltration, liver enzymes, and hepatocyte apoptosis after reperfusion were lower in the GdCl3 and Urge-8 groups than those in the ischemia control group. CONCLUSIONS: Blockades of Kupffer cells' activity and neutrophil infiltration by GdCl3 and Urge-8 eliminate neutrophil-mediated hepatic injury and enhance subsequent hepatic regeneration during liver ischemiareperfusion.     

乌司他丁联合缺血预处理对大鼠肝缺血再灌注损伤的影响

目的探讨乌司他丁(UTI)预处理和缺血预处理(IPC)联合应用对大鼠肝缺血再灌注损伤的影响及可能的作用机制。方法选择雄性SD大鼠50只,随机分为5组,分别为对照(sham)组、缺血再灌注(IR)组、IPC组、UTI组、UTI联合缺血预处理(UCI)组。术后采集下腔静脉血并取肝组织标本,检测血清AST、ALT、TNFɑ,肝组织髓过氧化物酶(MPO)、NF-κB、肝组织湿干比(W/D)及光镜观察肝组织病理形态学变化。计量资料组间比较采用单因素方差分析,进一步两两比较采用LSD-t检验。结果所检测的血清ALT、AST、TNFα水平和肝组织MPO、NF-κB、W/D值,IR组、IPC组、UTI组、UCI组均明显高于sham组(P值均<0.05),而IPC组、UTI组、UCI组均明显低于IR组(P值均<0.05),UTI组明显低于IPC组(P值均<0.05),UCI组明显低于IPC组、UTI组(P值均<0.05)。肝脏病理学检查示IR组、IPC组、UTI组、UCI组与sham组比较,肝组织损伤明显(P值均<0.05),而IPC组、UTI组、UCI组均比IR组肝组织损伤程度轻(P值均<0.05),UTI组肝组织损伤轻于IPC组(P值均<0.05),UCI组肝组织损伤轻于IPC组、UTI组(P值均<0.05)。结论 UTI和UCI对肝脏缺血再灌注损伤均有保护作用,二者联合应用时,明显增强了对肝脏缺血再灌注损伤的保护效应。其发生机制可能与抑制了NF-κB表达,减少TNFɑ、MPO的释放,减轻了肝脏的炎症反应有关。     

Physiological role of sinusoidal endothelial cells and Kupffer cells and their implication in the pathogenesis of liver injury

We reviewed the morphological characteristics and physiological functions of hepatic sinusoidal endothelial cells (SECs) and Kupffer cells (KCs), both of which are major components of the hepatic sinusoid, and we showed the implication of these hepatic sinusoidal lining cells in the pathophysiology of the liver, based on our experimental studies. The most outstanding feature of SECs is that they are provided with numerous fenestrae, thereby allowing direct communication between the sinusoidal lumen and the space of Disse. Physiologically, SECs play a role in filtration function, endocytic function, and putative participation in the regulation of sinusoidal blood flow. As for KCs, they account for major portion of fixed macrophages in the entire body, and exhibit vigorous activity for phagocytosis, and produce many kinds of soluble mediators such as cytokines, prostanoids, oxygen radicals, and proteases. To determine whether these cells are implicated in pathophysiological processes in the liver we directed our attention to liver injury associated with sepsis and cold‐preservation injury of liver tissue. In a septic rat model, we found that when KCs that included hepatic macrophages were activated, they released excess tissue‐toxic mediators, probably leading to SEC damage. In the cold‐preserved liver, we demonstrated that KCs were functionally activated and that the morphology of SECs was destroyed. When the liver was reperfused with plasma and a leucocyte suspension, hypercoagulability and increased leucocyte adherence occurred. In both experimental models, we demonstrated that KC blockade ameliorated the liver injury, and this was associated with the morphological improvement of SECs. Thus, we showed the pathogenetic implication of KCs and SECs, due possibly to microcirculatory disturbance in the hepatic sinusoid, and further emphasized the involvement of activated KCs in SEC impairment.     

Effects of hypoxia-reoxygenation on isolated liver nonparenchymal cells

To clarify the relationship between Kupffer cells (KC) and hepatocytes in hepatic ischemia-reperfusion injury, isolated liver nonparenchymal cells (NPC), including a large proportion of KC, from C3H/HeN and C3H/HeJ mice were utilized in an in vitro hypoxia-reoxygenation system which enabled precise control of the oxygen concentration in the circumferential air during incubation. The viability of NPC, concentrations of cytokines and superoxides released from NPC, and the effects of antioxidants on hypoxiareoxygenation were investigated. The results were: (1) The deterioration of NPC was slow under hypoxia, but a significant decrease in their viability was observed with reoxygenation. These results were virtually identical in C3H/HeN and C3H/HeJ mice. (2) The concentration of tumor necrosis factor (TNF)-α from NPC of C3H/HeJ was much lower than that from NPC of C3H/HeN, and production of O₂^? was lower in the NPC of C3H/HeJ than in C3H/HeN, but changes in the viability of NPCs which were reoxygenated following various intervals of hypoxia were almost identical in both types of mice. (3) Viability after reoxygenation was improved by the addition of catalase or superoxide dismutase (SOD), and further improved with the combined use of catalase and SOD. These results suggested that the changes in KC function after reoxygenation decreased the viability of the cells, due predominantly to the release of reactive oxygen metabolites, not to the release of TNF-α.     

白藜芦醇对心肌微血管内皮细胞缺血再灌注损伤的保护作用

目的观察白藜芦醇对缺血再灌注损伤心肌微血管内皮细胞(cardiac microvascular endothelial cells,CMECs)的保护作用。方法培养大鼠CMECs,模拟缺血再灌注损伤,随机分为对照组、缺血再灌注组及白藜芦醇组,采用四甲基偶氮唑盐微量酶反应比色法检测细胞活性;Annexin V-FITC/PI双标记流式细胞术检测CMECs凋亡率;酶联免疫吸附法检测半胱天冬酶3(caspase-3)活性、丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性。结果与对照组比较,缺血再灌注组和白藜芦醇组吸光度值明显降低(P<0.01);CMECs凋亡率、caspase-3相对活性、MDA含量、SOD活性明显升高,差异有统计学意义(P<0.05.P<0.01);与缺血再灌注组比较,白藜芦醇组吸光度值、SOD活性明显升高[(0.47±0.06)vs(0.14±0.04),(28.9±2.9)μU/L vs(22.4+2.2)μU/L,P<0.01];CMECs凋亡率、caspase-3相对活性、MDA含量明显降低.差异有统计学意义[(15.6±0.4)%vs(38.6±0.6)%,(152.1±13.3)vs(307.2±25.3),(9.2±0.7)μmol/L vs(13.5±1.2)μmol/L,P<0.01]。结论白藜芦醇可减轻CMECs的缺血再灌注损伤,这种保护作用可能是通过抗氧化和抗调亡来实现。