线粒体功能障碍与心肌缺血再灌注损伤

<正>近年来,随着溶栓治疗、冠状动脉旁路移植术、PCI等在临床的广泛应用,再灌注损伤越来越受到广泛的关注。心肌缺血再灌注损伤是指经历一定时间缺血的心肌组织在恢复血流灌注后损伤加重的现象,包括心律失常、心肌收缩功能下降和再灌注心肌不可逆损伤等。在再灌注损伤过程中,线粒体(mitochondria)功能障碍是一个非常重要的病理机制,包括线粒体ATP生成减少、Ca2+过荷、活性氧大量产生     

线粒体移植在心肌缺血再灌注损伤中的作用

线粒体移植是可改善线粒体功能障碍导致的心肌损伤、维持心脏稳态的新兴技术.该文总结了线粒体移植产生心肌保护的作用机制,介绍了线粒体内化、来源、移植方法以及线粒体移植在心肌缺血再灌注损伤中的应用.线粒体移植为心肌缺血再灌注损伤的临床治疗提供了新思路.     

线粒体途径保护心肌缺血再灌注损伤的研究进展

线粒体是细胞能量代谢和细胞内信号传导过程的关键细胞器,参与多种复杂信号介导的细胞生存和死亡。线粒体功能障碍及由此产生的氧化应激与心肌缺血再灌注损伤密切相关,保护线粒体功能将有助于减缓心肌损伤的严重程度或进展。最近,线粒体生物学进展启发人们研制作用于线粒体的选择性靶向药物,保护心肌缺血再灌注损伤。本文就此做一综述。     

褪黑素改善线粒体质量控制减轻心肌缺血再灌注损伤的研究进展

褪黑素具有调节昼夜节律和内分泌节律、抗炎、抗氧化等生物学功能。衰老和受损线粒体是氧化应激的主要源头, 线粒体质量控制对维持正常线粒体功能至关重要。心肌缺血再灌注损伤是冠心病再灌注治疗的重要并发症, 目前缺乏有效干预策略。线粒体功能障碍和氧化应激被认为是心肌再灌注损伤的核心机制之一, 靶向线粒体干预是再灌注损伤潜在治疗方向。近年来的研究发现, 褪黑素从多种途径改善线粒体结构和功能。该文从线粒体质量控制出发, 综述褪黑素改善心肌缺血再灌注损伤的机制, 并探讨其在心肌缺血再灌注损伤预防与治疗中的应用前景。     

硝酸甘油及线粒体乙醛脱氢酶对心肌保护作用的研究进展

缺血预处理是预防心脏缺血再灌注损伤有效的方法之一,近来发现:药物预处理也能够模拟缺血预处理的机制,减轻心肌缺血再灌注损伤。硝酸甘油预处理能保护心肌,减轻缺血再灌注损伤;其机制与预处理保护机制中线粒体内信号通路有关。线粒体乙醛脱氢酶是硝酸甘油的主要代谢酶,其本身活性的增高也能减轻心肌缺血再灌注损伤。     

微小RNA参与心肌缺血再灌注损伤的作用机制及研究进展

心肌缺血再灌注损伤是影响冠心病尤其是急性心肌梗死血运重建治疗效果的重要原因之一,近年来,众多研究发现微小RNA在心肌缺血再灌注过程中发挥调控作用,上调或者下调靶微小RNA的表达可减轻心肌缺血再灌注损伤,为临床上心肌保护提供了新的治疗靶点,现将围绕微小RNA在心肌缺血再灌注损伤中的调控机制及临床应用等方面的新进展进行综述。     

微小核糖核酸对缺血再灌注损伤心肌线粒体调节及临床应用的探讨

缺血性心脏病是目前全球首位致病和致残的疾病之一,给公共卫生系统和病人生活都带来巨大的负担,缺血/再灌注损伤是其中最常见的病理生理机制.微小核糖核酸(miRNAs)是近年来心肌缺血再灌注损伤中研究较多的调控因子,对于线粒体的功能有重要的调节作用,尤其是定位于线粒体中的miRNAs (mitomiRNAs)可通过改变关键信...     

心肌缺血再灌注损伤中的线粒体相关细胞器串扰

细胞器损伤是导致心肌缺血再灌注损伤的重要因素。这种损伤会导致线粒体及相关细胞器的功能改变。线粒体与其他细胞器的串扰同样影响心脏缺血再灌注损伤的发生发展,例如线粒体相关内质网膜使得线粒体和内质网“无缝连接”,调节线粒体和内质网之间的细胞器和代谢物(包括离子、脂质和蛋白质)交换,从而影响心肌缺血再灌注损伤。然而,线粒体与相关细胞器串扰是触发心肌缺血再灌注损伤的关键因素,目前相关报道有限。因此,该文阐述了线粒体与内质网、溶酶体和细胞核串扰在心肌缺血再灌注损伤中的作用,旨在为靶向线粒体与其他细胞器的串扰治疗心肌缺血再灌注损伤的研究提供一定的理论依据。     

心肌缺血再灌注损伤研究进展

正心肌缺血本质是心肌的氧供需求平衡失调,缺血心肌可呈现功能、形态及代谢等方面的损伤[1,2],减少心肌缺血后损伤的最有效办法就是恢复组织灌注。但是,目前遇到的问题是缺血心肌在恢复血液再灌注后,出现了心律失常、心肌能量代谢障碍、心肌细胞超微结构的变化及微血管内皮细胞(VEC)损伤和功能障碍等一系列的功能、结构、代谢及心肌细胞电生理特性等各个方面的损伤进一步加重的现象,即心肌缺血/再灌     

线粒体、线粒体三磷酸腺苷敏感性钾通道与心肌保护

线粒体是真核细胞中重要和独特的细胞器，在细胞凋亡和坏死过程中都发挥着关犍作用。对心肌缺血再灌注(ischemia—reperfusion，I／R)损伤机制的研究也表明，线粒体的功能损害是导致I／R心肌不可逆损伤的重要原因之一。本文综述了线拉体友线粒体KATP通道在缺血心肌保护方面的重要意义。     

Protection of the Myocardium with Sodium-Hydrogen Exchange Inhibitors: A Cardiac Surgical Perspective

Strategies for myocardial protection in cardiac surgery are directed at the prevention of procedure-induced ischemia/reperfusion injury as well as metabolic resuscitation in acute ischemic syndromes. Postreperfusion myocardial dysfunction remains a significant clinical problem, most importantly in certain high-risk patient groups. The large body of experimental evidence demonstrating a significant role for sodium-hydrogen exchange activation in myocardial ischemia/reperfusion injury suggests that the ability to pharmacologically inhibit the exchanger presents a promising new approach to current myocardial preservation techniques.     

Inhibition of N-ethylmaleimide-sensitive factor protects against myocardial ischemia/reperfusion injury

Exocytosis of endothelial granules promotes thrombosis and inflammation and may contribute to the pathophysiology of early reperfusion injury following myocardial ischemia. TAT-NSF700 is a novel peptide that reduces endothelial exocytosis by inhibiting the ATPase activity and disassembly activity of N-ethylmaleimide-sensitive factor (NSF), a critical component of the exocytic machinery. We hypothesized that TAT-NSF700 would limit myocardial injury in an in vivo murine model of myocardial ischemia/reperfusion injury. Mice were subjected to 30 minutes of ischemia followed by 24 hours of reperfusion. TAT-NSF700 or the scrambled control peptide TAT-NSF700scr was administered intravenously 20 minutes before the onset of ischemia. Myocardial ischemia/reperfusion caused endothelial exocytosis, myocardial infarction, and left ventricular dysfunction. However, TAT-NSF700 decreased von Willebrand factor levels after myocardial ischemia/reperfusion, attenuated myocardial infarct size by 47%, and preserved left ventricular structure and function. These data suggest that drugs targeting endothelial exocytosis may be useful in the treatment of myocardial injury following ischemia/reperfusion.     

Stunning: Damaging or protective to the myocardium?

Summary There are several potential outcomes of myocardial ischemia. When ischemia is severe and prolonged, irreversible damage occurs and there is no recovery of contractile function. Interventions aimed at reducing mechanical activity and oxygen demand, either before ischemia or during reperfusion, have been shown to delay the onset of ischemic damage and to improve recovery on reperfusion.When myocardial ischemia is less severe but still prolonged, myocytes may remain viable but exhibit depressed contractile function. Under these conditions, reperfusion restores complete contractile performance. This type of ischemia, leading to a reversible, chronic left ventricular dysfunction, has been termed hibernating myocardium. Depression of mechanical activity is, actually, a protective mechanism whereby the hibernating cells reduce their oxygen demands in the setting of reduced oxygen supply.A third possible outcome after a short period of myocardial ischemia is a transient postischemic ventricular dysfunction, a situation termed stunned myocardium. As in the case of hibernating myocardium, the depressed contractile function occurring during stunning could be a protective mechanism, allowing the reperfused cells to gradually recover their metabolism and function.     

Down’s syndrome and myocardial reperfusion injury

Down syndrome is known to be an independent risk factor for mortality after surgical repair of congenital heart anomalies. It is also associated with neurodegenerative disease and accelerated aging. The mechanism of the latter features has been attributed to abnormal handling of oxygen-free radicals as well as mitochondrial dysfunction. These properties also place the child with Down syndrome at a risk of an exaggerated myocardial ischemia/reperfusion injury.A 6 month old child with Down syndrome is reported who suffered from obvious clinical ischemia/reperfusion injury following an uncomplicated repair of complete AV canal. Both intraoperative as well as postoperative echocardiography documented a satisfactory technical repair. After resting the heart on ECMO the child’s myocardial function returned to normal.The mechanisms by which patients with Down syndrome are at risk of ischemia/reperfusion injury are reviewed. Future studies should focus on specific approaches for myocardial protection in the child with Down syndrome undergoing cardiac surgery.     

缺血后处理的研究现状

心肌缺血后长时间的冠状动脉再灌注前对缺血心肌进行反复、短暂的再缺血干预,以减轻再灌注损伤,称为缺血后处理。它是缺血心脏有效的内源性保护现象,可以减轻缺血-再灌注后心肌坏死与功能障碍,减少恶性心律失常的发生。人们对其发生机理、信号通路以及潜在的临床应用等方面已作了较多研究。现对缺血后处理的研究现状做一综述。     

Mitochondrial Involvement in Cardiac Apoptosis During Ischemia and Reperfusion: Can We Close the Box?

Myocardial ischemia is the main cause of death in the Western societies. Therapeutic strategies aimed to protect the ischemic myocardium have been extensively studied. Reperfusion is the definitive treatment for acute coronary syndromes, especially acute myocardial infarction; however, reperfusion has the potential to exacerbate tissue injury, a process termed reperfusion injury. Ischemia/reperfusion (I/R) injury may lead to cardiac arrhythmias and contractile dysfunction that involve apoptosis and necrosis in the heart. The present review describes the mitochondrial role on cardiomyocyte death and some potential pharmacological strategies aimed at preventing the opening of the box, i.e., mitochondrial dysfunction and membrane permeabilization that result into cell death. Data in the literature suggest that mitochondrial disruption during I/R can be avoided, although uncertainties still exist, including the fact that the optimal windows of treatment are still fairly unknown. Despite this, the protection of cardiac mitochondrial function should be critical for the patient survival, and new strategies to avoid mitochondrial alterations should be designed to avoid cardiomyocyte loss.     

Ischemia/reperfusion injury and cardioprotective mechanisms: Role of mitochondria and reactive oxygen species

Reperfusion therapy must be applied as soon as possible to attenuate the ischemic insult of acute myocardial infarction(AMI).However reperfusion is responsible for additional myocardial damage,which likely involves opening of the mitochondrial permeability transition pore(mPTP).In reperfusion injury,mitochondrial damage is a determining factor in causing loss of cardiomyocyte function and viability.Major mechanisms of mitochondrial dysfunction include the long lasting opening of mPTPs and the oxidative stress resulting from formation of reactive oxygen species(ROS).Several signaling cardioprotective pathways are activated by stimuli such as preconditioning and postconditioning,obtained with brief intermittent ischemia or with pharmacological agents.These pathways converge on a common target,the mitochondria,to preserve their function after ischemia/reperfusion.The present review discusses the role of mitochondria in cardioprotection,especially the involvement of adenosine triphosphate-dependent potassium channels,ROS signaling,and the mPTP.Ischemic postconditioning has emerged as a new way to target the mitochondria,and to drastically reduce lethal reperfusion injury.Several clinical studies using ischemic postconditioning during angioplasty now support its protective effects,and an interesting alternative is pharmacological postconditioning.In fact ischemic postconditioning and the mPTP desensitizer,cyclosporine A,have been shown to induce comparable protection in AMI patients.     

Melatonin attenuates myocardial ischemia‐reperfusion injury via improving mitochondrial fusion/mitophagy and activating the AMPK‐OPA1 signaling pathways

Optic atrophy 1 (OPA1)‐related mitochondrial fusion and mitophagy are vital to sustain mitochondrial homeostasis under stress conditions. However, no study has confirmed whether OPA1‐related mitochondrial fusion/mitophagy is activated by melatonin and, consequently, attenuates cardiomyocyte death and mitochondrial stress in the setting of cardiac ischemia‐reperfusion (I/R) injury. Our results indicated that OPA1, mitochondrial fusion, and mitophagy were significantly repressed by I/R injury, accompanied by infarction area expansion, heart dysfunction, myocardial inflammation, and cardiomyocyte oxidative stress. However, melatonin treatment maintained myocardial function and cardiomyocyte viability, and these effects were highly dependent on OPA1‐related mitochondrial fusion/mitophagy. At the molecular level, OPA1‐related mitochondrial fusion/mitophagy, which was normalized by melatonin, substantially rectified the excessive mitochondrial fission, promoted mitochondria energy metabolism, sustained mitochondrial function, and blocked cardiomyocyte caspase‐9‐involved mitochondrial apoptosis. However, genetic approaches with a cardiac‐specific knockout of OPA1 abolished the beneficial effects of melatonin on cardiomyocyte survival and mitochondrial homeostasis in vivo and in vitro. Furthermore, we demonstrated that melatonin affected OPA1 stabilization via the AMPK signaling pathway and that blockade of AMPK repressed OPA1 expression and compromised the cardioprotective action of melatonin. Overall, our results confirm that OPA1‐related mitochondrial fusion/mitophagy is actually modulated by melatonin in the setting of cardiac I/R injury. Moreover, manipulation of the AMPK‐OPA1‐mitochondrial fusion/mitophagy axis via melatonin may be a novel therapeutic approach to reduce cardiac I/R injury.     

Myocardium reperfusion injury

The phenomenon of ischemia/reperfusion injury is described in the experimental models of acute myocardial infarction（AMI）,causing additional functional and structural damage to the acute reperfused myocardium,and ischemic preconditioning refers to the myocardial ischemia after a long period of reperfusion before one or several shortoccasional duplication of myocardial ischemia /reperfusion1,which can increase myocardial ischemic tolerance.The therapeutic strategies for AMI have focused on myocardial ischemia /reperfusion injury,which accounts for a significant part of the final infarct size.Although experiments in the last 20 years have reported that pharmacological interventions at reperfusion might reduce myocardial reperfusion injury,this could not be confirmed in human studies.An alternative to chemical modifiers,postconditioning（brief repeated periods of ischemia applied at the onset of reperfusion） is another method proven to be efficient in animal models and to be confirmed in recent human studies.This simple method,applied in the first minute of reperfusion,reduces the final infarct size by 30%-50%.This review will focus on the mechanisms,pharmacological preconditioning,postconditioning technique,which is easily applicable in human patients in the setting of AMI.     

Cardioprotection and altered mitochondrial adenine nucleotide transport

It is becoming increasingly clear that mitochondrial dysfunction is critically important in myocardial ischemic injury, and that cardioprotective mechanisms must ultimately prevent or attenuate mitochondrial damage. Mitochondria are also essential for energy production, and therefore prevention of mitochondrial injury must not compromise oxidative phosphorylation during reperfusion. This review will focus on one mitochondrial mechanism of cardioprotection involving inhibition of adenine nucleotide transport across the outer mitochondria membrane under de-energized conditions. This slows ATP hydrolysis by the mitochondria, and would be expected to lower mitochondrial membrane potential during ischemia, to inhibit calcium uptake during ischemia, and potentially to reduce free radical generation during early reperfusion. Two interventions that similarly inhibit mitochondrial adenine nucleotide transport are Bcl-2 overexpression and GSK inhibition. A possible final common mechanism shared by both of these interventions is discussed.