TNF-α与G-CSF在脑缺血-再灌注损伤中的研究

再灌注损伤是由多种原因引起的复杂的病理生理过程,而级联的炎症反应是导致脑细胞损伤的重要病理环节。脑缺血再灌注后,浸润的炎性细胞产生的大量炎性介质,在再灌注损伤中占有重要地位。肿瘤坏死因子α(TNF-α)是一种具有广泛生物学功能的细胞因子,参与机体免疫应答和炎症反应TNF-α是细胞间粘附分子-1(ICAM-1)表达的强诱导剂,抑制细胞粘附分子(ICAM-1)表达可显著减低再灌注时白细胞粘附活化,减少损伤脑面积起保护作用。粒细胞集落刺激因子(G-CSF)能通过STAT途径减少缺血区肿瘤坏死因子-α等的释放,引起人们对其在脑缺血-再灌注损伤中的作用的极大关注。     

TNF-α与G—CSF在脑缺血-再灌注损伤中的研究

再灌注损伤是由多种原因引起的复杂的病理生理过程,而级联的炎症反应是导致脑细胞损伤的重要病理环节。脑缺血再灌注后,浸润的炎性细胞产生的大量炎性介质,在再灌注损伤中占有重要地位。肿瘤坏死因子α（TNF-α）是一种具有广泛生物学功能的细胞因子,参与机体免疫应答和炎症反应TNF-α是细胞间粘附分子-1（ICAM-1）表达的强诱导剂,抑制细胞粘附分子（ICAM-1）表达可显著减低再灌注时白细胞粘附活化,减少损伤脑面积起保护作用。粒细胞集落刺激因子（G-CSF）能通过STAT途径减少缺血区肿瘤坏死因子-α等的释放,引起人们对其在脑缺血-再灌注损伤中的作用的极大关注。     

白藜芦醇减轻脑缺血再灌注损伤与激活Wnt/β-catenin相关

研究白藜芦醇对脑缺血再灌注损伤的作用及机制。利用结扎大脑中动脉的方法制备局灶脑缺血再灌注损伤模型。将实验大鼠随机分为假手术组,脑缺血再灌注损伤组,白藜芦醇组和尼莫地平组,观察白藜芦醇对大鼠肿瘤坏死因子α(TNF-α)、单核细胞趋化因子-1(MCP-1)、白介素-6(IL-6)、Wnt、β-catenin、Bax和BCL-2的表达以及对大鼠神经行为和脑梗死面积的影响。结果显示白藜芦醇可明显改善大鼠神经功能缺陷和减少脑梗死面积,并可上调Wnt、β-catenin、cyclin D1、survivin、和BCL-2的表达,下调促炎症细胞因子TNF-α、MCP-1和IL-6的表达。说明白藜芦醇可激活Wnt/β-catenin信号通路发挥对脑缺血再灌注损伤的保护作用。     

MEK/ERK信号通路与脑缺血再灌注损伤

在脑缺血病灶中,中心区神经元坏死为主,周围以缺血半暗带凋亡为主,抑制半暗带细胞的凋亡,可以减少细胞的死亡和脑梗死的面积,因此改善半暗带是治疗脑卒中的关键环节.目前发现MAPK分布于整个中枢神经系统中,MEK/ERK信号通路参与细胞生长、发育、细胞抗凋亡等过程,在脑缺血再灌注损伤过程中有MEK/ERK信号通路的参与,MEK/ERK通路通过影响Bcl-2家族成员的活化和表达调控内源性凋亡途径,ERK通过对细胞周期的调控,抑制胶质细胞大量活化和过度增殖,减少了有害因子并改善局部微循环,从而减少神经元的凋亡.可能为脑血管的防治开辟一条新的途径.本文就MEK/ERK信号通路的结构特点与脑缺血再灌注损伤相关作用机制作一综述.     

硫化氢对抗脑缺血再灌注损伤的机制研究进展

硫化氢（H2S）是一种新型内源性气体信使分子,在许多生理和病理生理过程中,尤其在神经保护中,扮演重要角色,既是神经调节剂, 也是神经保护剂。近年来的研究发现,H2S对于脑缺血再灌注损伤具有积极的防治作用,它可通过抗氧化应激、抗炎及抗细胞凋亡等多个途径, 对脑缺血再灌注损伤起保护作用,具有良好的临床应用前景。简介脑内H2S生成途径,综述H2S在中枢神经系统中的生物学效应及其对脑 缺血再灌注损伤的保护作用与机制研究进展,以期为脑缺血再灌注损伤的临床防治提供新思路。     

转基因鼠在脑缺血氧化应激研究中的应用

活性氧自由基作为脑内一类重要的病理因素直接或间接地参与脑缺血/再灌注的损伤过程。氧自由基不仅受到脑内促氧化酶与抗氧化酶间平衡的调节,同时也参与了细胞内信号转导通路,在神经元死亡中发挥着决定性作用。近年来,转基因及基因敲除鼠已广泛应用于这些影响活性氧自由基的形成和清除过程的酶类物质及各种介导细胞死亡与凋亡过程的蛋白质的研究中,为脑缺血/再灌注损伤治疗的基础及应用提供了必要条件。     

银杏叶提取物缓释剂穴位埋药线对局灶性脑缺血再灌注大鼠脑组织损伤及Nrf2/HO-1信号通路的影响

银杏叶提取物缓释剂穴位埋药线对局灶性脑缺血再灌注损伤大鼠脑组织损伤及其对Nrf2/HO-1信号通路的影响。采用改良线栓法制备脑缺血再灌注大鼠模型,银杏叶提取物缓释剂穴位埋药线后进行神经缺失症状评分,测定神经细胞病理学,检测丙二醛(MDA)、一氧化氮(NO)、超氧化物歧化酶(SOD)和谷胱甘肽(GSH)及脑组织Nrf2和HO-1 mRNA和蛋白的表达。结果表明银杏叶提取物缓释剂穴位埋药线可显著改善脑缺血再灌注模型动物的神经功能,提高神经细胞存活率,显著降低MDA、NO含量,升高总SOD活性和GSH含量,调节Nrf2/HO-1 mRNA和蛋白的表达水平。银杏叶提取物缓释剂穴位埋药线具有抗脑缺血再灌注损伤作用,其机制可能与与激活Nrf2/HO-1途径,促进了Nrf2的核转位,使HO-1等抗氧化物质表达上调,提高了机体对氧化损伤的抗性有关。     

硫化氢对脑缺血再灌注损伤的保护作用

脑是人体对缺氧最敏感的器官,脑缺氧后会导致局部脑组织受损,当缺血脑组织恢复血流供应后,其损伤反而加重,即脑缺血再灌注损伤。硫化氢(hydrogen sulfide, H2S)是一种气体信号分子,同时也是新型的内源性神经调节物。不同浓度的H2S对神经元的作用有所不同。低浓度的H2S可通过抗氧化应激损伤、抑制炎症反应、抑制细胞凋亡、减轻脑血管内皮细胞损伤、调节细胞自噬等多种途径,在脑缺血再灌注损伤中发挥重要的保护作用,为临床诊治相关疾病提供了新思路。本文就脑缺血再灌注损伤时H2S对损伤脑组织保护作用的最新研究进展作一综述。     

长链非编码RNA、焦亡和心肌缺血-再灌注损伤

急性心肌梗死后的再灌注是挽救缺血心肌的唯一方法,但是血流的恢复可能导致心肌缺血-再灌注损伤. 长链非编码RNA(lncRNA)和焦亡都参与了心肌缺血-再灌注损伤的病理过程并发挥重要作用. lncRNA能直接或者间接作用于焦亡信号通路相关蛋白质,对包括心肌缺血-再灌注损伤在内的多种病理过程进行调控. 本文就lncRNA和焦亡在心肌缺血-再灌注损伤中的作用做一综述,以进一步探索两者关系,为防治心肌缺血-再灌注损伤提供新思路.     

心肌缺血后处理胞内信号转导研究进展

缺血后处理对心肌再灌注损伤的保护是多因素参与的复杂过程。后处理对心肌的保护除了通过减少活性氧类物质的产生、抑制线粒体内钙超载、减轻内皮功能失调等被动作用外,还可主动激活再灌注损伤补救激酶（reperfusion injury salvage kinase,RISK）途径及其他蛋白激酶而实现。本文将对心肌缺血后处理中RISK通路的研究进展作一综述。     

Cerebral ischemia-reperfusion is modulated by macrophage-stimulating 1 through the MAPK-ERK signaling pathway

Cerebral ischemia-reperfusion (IR) injury is associated with mitochondrial damage. Macrophage-stimulating 1 (MST1) reportedly stimulates mitochondrial apoptosis by suppressing BCL-2. We investigated whether MST1 promotes the progression of cerebral IR injury by inducing mitochondrial dysfunction in vivo and in vitro. Western blot analysis, quantitative polymerase chain reaction, immunofluorescence, and mitochondrial function assays were conducted in cells from wild-type and Mst1-knockout mice subjected to cerebral IR injury. MST1 expression in wild-type glial cells increased following cerebral IR injury. Cerebral IR injury reduced the mitochondrial membrane potential and mitochondrial metabolism in glial cells, while it enhanced mitochondrial reactive oxygen species generation and mitochondrial calcium levels in these cells. The deletion of Mst1 attenuated cerebral IR injury by improving mitochondrial function and reducing mitochondrial damage. The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway was suppressed in wild-type glial cell upon cerebral IR injury but was reactivated in Mst1-knockout glial cell. Accordingly, blocking the MAPK/ERK pathway abolished the beneficial effects of Mst1 deletion during cerebral IR injury by inducing mitochondrial damage in glial cells. Our results suggest that cerebral IR injury is associated with MST1 upregulation in the brain, while the genetic ablation of Mst1 can attenuate mitochondrial damage and sustain brain function following cerebral IR injury.     

活性氮自由基:脑缺血再灌注损伤过程中引起血脑屏障破坏及调节神经修复的双刃剑(英文)

在脑缺血再灌注损伤中,自由基发挥着重要作用。脑缺血及再灌注可产生大量的自由基,随着这些自由基的聚集,会引发一系列的分子级联反应,从而增加血脑屏障的通透性,诱发脑水肿、出血、炎症反应及细胞死亡。以一氧化氮(NO)及过氧亚硝基阴离子(ONOO-)为代表的活性氮(reactive nitrogen species,RNS),是自由基的重要组成部分,它们在脑缺血再灌注损伤中作用显著。一方面,活性氮能激活基质金属蛋白酶(MMPs),破坏血脑屏障。MMPs作为一大类含2价锌离子的水解酶,其激活可以降解脑血管及神经元细胞外基质。脑缺血再灌注损伤产生NO和ONOO-,它们均可以通过激活MMPs,降解紧密连接蛋白,从而破坏血脑屏障。另一方面,近期研究发现,活性氮也参与了脑缺血后神经再生及修复的调节过程。因此,了解这些活性小分子在血脑屏障破坏及神经再生中的复杂生物活性将很有意义。小窝蛋白1(Caveolin-1)就是活性氮自由基的重要靶分子,它是一种细胞表面的穴样内陷(caveolae)中的膜蛋白,可以通过抑制MMPs的激活保护血脑屏障的完整性。下调Caveolin-1的表达将引起血脑屏障的破坏。脑缺血所产生的NO能下调Caveolin-1的表达,而Caveolin-1的下调,能引起NO合酶的增加,促进生成更多的NO。活性氮与Caveolin-1互相作用,形成了一个反馈回路,通过激活MMPs而造成血脑屏障的不断破坏。此外,Caveolin-1通过调节不同的信号通路,抑制神经干细胞的增长及向神经元分化。因此,活性氮也很可能通过调节Caveolin-1及其他信号通路调控神经再生。在这篇文章中,我们对活性氮在血脑屏障及神经再生中的近期研究进展进行了综述。我们认为,活性氮可能在脑缺血再灌注中起双重作用,既是细胞毒性分子,亦可能是神经再生中的重要信号分子,其作用与其在神经元、内皮细胞及其微环境中产生的量有重要的关系。     

Neuroprotective effect of glutamate-substituted analog of gramicidin A is mediated by the uncoupling of mitochondria

BackgroundReactive oxygen species are grossly produced in the brain after cerebral ischemia and reperfusion causing neuronal cell death. Mitochondrial production of reactive oxygen species is nonlinearly related to the value of the mitochondrial membrane potential with significant increment at values exceeding 150 mV. Therefore, limited uncoupling of oxidative phosphorylation could be beneficial for cells exposed to deleterious oxidative stress-associated conditions by preventing excessive generation of reactive oxygen species.MethodsProtonophoric and uncoupling activities of different peptides were measured using pyranine-loaded liposomes and isolated mitochondria. To evaluate the effect of glutamate-substituted analog of gramicidin A ([Glu1]gA) administration on the brain ischemic damage, we employed the in vitro model of neuronal hypoxia using primary neuronal cell cultures and the in vivo model of cerebral ischemia induced in rats by the middle cerebral artery occlusion.Results[Glu1]gA was the most effective in proton-transferring activity among several N-terminally substituted analogs of gramicidin A tested in liposomes and rat brain and liver mitochondria. The peptides were found to be protective against ischemia-induced neuronal cell death and they lowered mitochondrial membrane potential in cultured neurons and diminished reactive oxygen species production in isolated brain mitochondria. The intranasal administration of [Glu1]gA remarkably diminished the infarct size indicated in MR-images of a brain at day 1 after the middle cerebral artery occlusion. In [Glu1]gA-treated rats, the ischemia-induced brain swelling and behavioral dysfunction were significantly suppressed.ConclusionsThe glutamate-substituted analogs of gramicidin A displaying protonophoric and uncoupling activities protect neural cells and the brain from the injury caused by ischemia/reperfusion.General significance[Glu1]gA may be potentially used as a therapeutic agent to prevent neuron damage after stroke.     

高压氧预处理对大鼠局灶性脑缺血再灌注损伤的保护作用

目的:研究高压氧预处理对大鼠脑缺血再灌注损伤的保护作用。方法:36只SD大鼠随机分为假手术组、模型组及高压氧预处理组,每组12只。高压氧预处理组大鼠在造模前5天给予高压氧预处理。采用线栓法建立大鼠脑缺血再灌注模型,观察高压氧预处理对脑缺血再灌注损伤大鼠神经功能缺损评分、脑梗死面积的影响,检测大鼠缺血脑组织COX-2 mRNA和蛋白的表达以及IL-1β、TNF-α、MDA的含量。结果:高压氧预处理可明显改善脑缺血再灌注大鼠神经功能缺损评分,减少脑梗死面积,降低COX-2m RNA和蛋白表达量,抑制IL-1β、TNF-α的表达,降低MDA水平。结论:高压氧预处理对大鼠脑缺血再灌注损伤具有明显的保护作用,其机制可能与抑制IL-1β、TNF-α、COX-2的表达以及减弱脂质过氧化反应有关。     

APE/Ref-1在中枢神经系统氧化应激反应中的保护作用

化学性质活泼的自由基（free radicals）在保持产生和清除平衡的稳衡性动态下能履行正常的生理功能,但超过生物体的清除能力则可导致多种疾病.无嘌呤/无嘧啶核酸内切酶/氧化还原因子1（apurinic/apyrimidinic endonuclease/redox-factor 1, APE/Ref-1）是一种体内分布广泛的多功能蛋白质,通过修复DNA的无嘌呤/无嘧啶（apurinic/apyrimidinic, AP）部位参与DNA的碱基切除修复(base excision repair, BER).APE/Ref-1还可通过还原许多转录因子的半胱氨酸残基使之易于与DNA结合而调控真核细胞的基因表达.APE/Ref-1的抗细胞凋亡作用使其在自由基所致中枢神经系统病变如脑缺血-再灌注损伤、神经退行性病变、脑动脉粥样硬化中发挥了重要作用.     

Reactive oxygen and ischemia/reperfusion injury of the liver

Pharmacological experiments suggested that reactive oxygen species contribute to ischemia-reperfusion injury of the liver. Since there is no evidence that quantitatively sufficient amounts of reactive oxygen are generated intracellularly to overwhelm the strong antioxidant defense mechanisms in the liver and cause parenchymal cell injury, the role of reactive oxygen in the pathogenesis remains controversial. This paper reviews the data and conclusions obtained with pharmacological intervention studies in vivo, the sources of reactive oxygen in the liver as well as the growing evidence for the importance of liver macrophages (Kupffer cells) and infiltrating neutrophils in the pathogenesis. A comprehensive hypothesis is presented that focuses on the extracellular generation of reactive oxygen in the hepatic sinusoids, where Kupffer cell-derived reactive oxygen species seem to be involved in the initial vascular and parenchymal cell injury and indirectly also in the recruitment of neutrophils into the liver. Reactive oxygen species may also contribute to the subsequent neutrophil-dependent injury phase as one of the toxic mediators released by these inflammatory cells.     

The role of free radicals in asbestos-induced diseases.

Asbestos exposure causes pulmonary fibrosis and malignant neoplasms by mechanisms that remain uncertain. In this review, we explore the evidence supporting the hypothesis that free radicals and other reactive oxygen species (ROS) are an important mechanism by which asbestos mediates tissue damage. There appears to be at least two principal mechanisms by which asbestos can induce ROS production; one operates in cell-free systems and the other involves mediation by phagocytic cells. Asbestos and other synthetic mineral fibers can generate free radicals in cell-free systems containing atmospheric oxygen. In particular, the hydroxyl radical often appears to be involved, and the iron content of the fibers has an important role in the generation of this reactive radical. However, asbestos also appears to catalyze electron transfer reactions that do not require iron. Iron chelators either inhibit or augment asbestos-catalyzed generation of the hydroxyl radical and/or pathological changes, depending on the chelator and the nature of the asbestos sample used. The second principal mechanism for asbestos-induced ROS generation involves the activation of phagocytic cells. A variety of mineral fibers have been shown to augment the release of reactive oxygen intermediates from phagocytic cells such as neutrophils and alveolar macrophages. The molecular mechanisms involved are unclear but may involve incomplete phagocytosis with subsequent oxidant release, stimulation of the phospholipase C pathway, and/or IgG-fragment receptor activation. Reactive oxygen species are important mediators of asbestos-induced toxicity to a number of pulmonary cells including alveolar macrophages, epithelial cells, mesothelial cells, and endothelial cells. Reactive oxygen species may contribute to the well-known synergistic effects of asbestos and cigarette smoke on the lung, and the reasons for this synergy are discussed. We conclude that there is strong evidence supporting the premise that reactive oxygen species and/or free radicals contribute to asbestos-induced and cigarette smoke/asbestos-induced lung injury and that strategies aimed at reducing the oxidant stress on pulmonary cells may attenuate the deleterious effects of asbestos.     

4-hydroxynonenal contributes to NGF withdrawal-induced neuronal apoptosis

Reactive oxygen species are a necessary triggering event for apoptosis of sympathetic neurons after nerve growth factor (NGF) withdrawal. Reactive oxygen species can lead to the generation of 4-hydroxynonenal (HNE), a highly reactive aldehyde that forms adducts with proteins. This covalent modification can activate or inhibit signal transduction pathways involved in the induction of apoptosis. This process may be clinically relevant because HNE-adduct immunoreactivity increases in several disease states. Here we evaluate the role of HNE-adducts in sympathetic neurons undergoing NGF-deprivation-induced apoptosis, a model of developmental programmed cell death. We show that HNE-adduct immunoreactivity is dramatically increased after NGF-withdrawal in an NADPH oxidase-dependent manner. Moreover, HNE-adducts appear to contribute to NGF-deprivation-induced apoptotic signal transduction because microinjected HNE-adduct antiserum protects sympathetic neurons from NGF withdrawal. In conclusion, this report suggests the direct contribution of endogenously generated HNE in the stimulation of apoptotic signal transduction in neurons.