促红细胞生成素预处理对缺血-再灌注心脏保护作用的研究进展

促红细胞生成素(EPO)原本是机体缺氧状态下分泌的刺激骨髓造血细胞,促进红系祖细胞增生分化的糖蛋白激素.近年来的研究表明,EPO尚具有多种非血液系统生理效应,是一种多功能的组织保护因子,其中包括对心脑等重要脏器缺血-再灌注损伤的保护作用.本文就EPO及其受体的结构,对缺血-再灌注心肌的保护作用及可能的机制等作一综述.     

低氧诱导因子-1/低氧反应元件通路在心肌保护中的研究进展

背景 低氧诱导因子-1 (hypoxia inducible factor-1,HIF-1)是目前公认的在缺氧状态下发挥重要作用的核转录因子,其活化后可介导低氧反应保护作用,在一定程度上能够减轻心肌的缺血/再灌注损伤(ischemic reperfusion injury,I/RI).目的 探究HIF-1/低氧反应元件(hypoxia response element,HRE)通路是如何被激活并发挥心肌保护的作用. 内容 从HIF-I的概述、调节以及HIF-1/HRE通路的激活机制及其心肌保护作用方面进行综述,并以HIF-1为靶点探究后处理的心肌保护作用的机制,对其在心肌保护作用中与其他关键性的转录因子之间的内在联系作一简要综述. 趋向 后处理能否激活HIF-1/HRE通路诱导红细胞生成素(erythropoietin,EPO)、血红素加氧酶1(hemeoxygenase1,HO-1)、诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)和血管内皮生长因子(vascular endothelial growth factor,VEGF)等保护性蛋白的表达,以减轻心肌I/RI,尚需进一步探讨.     

促红细胞生成素心肌保护作用的研究进展

促红细胞生成素（erythropoietin，EPO）是一种造血细胞生长因子，主要用于治疗多种原因所致的贫血。近年来其非造血生物作用逐渐引起关注，EPO具有组织保护作用，这一作用涉及多种不同组织和细胞，心肌保护一直是心血管病研究领域重要、关键的课题。EPO对心肌保护的作用近两年已渐有报道，这无疑为临床心肌保护的研究提供了新的思路和方向。现就EPO心肌保护作用的相关研究成果、发现以及有待解决的问题作一综述。     

促红细胞生成素与缺氧性脑损伤

促红细胞生成素(erythropoietin,EPO)是神经系统的一种神经营养因子和神经保护因子.EPO及其受体(erythro-poietin receptor,EPOR)在神经元、星形胶质细胞、少突胶质细胞、小胶质细胞和血管内皮细胞都可表达.脑组织缺氧缺血性损伤首先激活低氧诱发因子-1(HIF-1).后者促进EPO的分泌和表达,EPO和EPOR结合引发下游信号的级联反应表现出脑保护作用,其脑保护作用体现在抗凋亡、抗氧化、抗炎症等方面.众多动物实验和临床应用都证实重组人红细胞生成素(recombi-nant human erythmpoietin,rhEPO)对脑缺氧缺血性疾病具有脑保护作用.     

促红细胞生长素对神经保护作用及其机制

促红细胞生长素(erythropoietin,EPO)目前临床上治疗肾性贫血的主要药物。近来研究发现EPO在中枢神经系统内有大量分布及其受体的广泛表达,对中枢神经系统的发育起着重要的调节作用并对各种中枢神经系统损伤有很好的保护作用。本文针对EPO作为一个神经保护剂,对其神经保护作用和其保护机制作简要综述。     

七氟醚对心肌缺血/再灌注损伤的临床研究进展

背景 七氟醚的心肌保护作用得到广泛关注,大量基础研究表明七氟醚对心肌缺血/再灌注损伤(myocardial ischemia/reperfusion injury,MI/RI)具有确切的保护作用.然而,临床中关于七氟醚具有心肌保护作用的结论尚未完全统一.目的 通过总结近年的研究进展对七氟醚的心肌保护作用进行阐述.内容 不同心脏手术及非心脏手术中七氟醚药物处理的心肌保护效果.趋向 今后仍需加强对七氟醚心肌保护作用的临床研究,为围手术期患者的心肌保护提供更为可靠的理论依据.     

心肌缺血/再灌注损伤治疗新策略——迷走神经电刺激

背景 虽然缺血预处理(ischemic precondition,IPC)仍然是目前已知的最强大内源性心肌保护措施,但是因时机选择等原因其临床应用受到了极大的限制.大量动物实验证明,刺激迷走神经能够通过激活“胆碱能抗炎通路”、降低心肌交感神经兴奋性和抑制氧自由基的产生等作用机制,来减轻心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI).另外,也有少数随机对照临床研究证实了迷走神经刺激的心肌保护作用.目的 评价迷走神经刺激对心肌I/RI的保护作用.内容 包括迷走神经刺激的发现、发展,心肌保护作用的机制及其临床应用价值. 趋向 这一现象的发现为降低心肌I/RI提供了一个简单易行且费用低廉的措施.然而,在将迷走神经刺激推荐作为临床工作的常规措施之前,仍需进行更多大规模的临床研究,以评估和优化迷走神经刺激措施的保护作用.     

miRNA在缺血预处理保护心肌缺血/再灌注损伤中的研究进展

背景microRNAs(miRNAs)是一类由动物、 植物和病毒基因组编码的约由22个核苷酸组成的小分子单链RNA.近年来发现它在缺血预处理(ischemic preconditioning,IPC)中发挥着重要作用,有望成为研究治疗心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)的新靶点.目的 阐述不同miRNA在IPC保护心肌I/RI中的作用及其可能机制.内容IPC是经典的保护心肌I/RI的方法,IPC后心肌中miRNA表达谱发生改变,其中miR-1、miR-21、miR-133b-5p、miR-199a、miR-144/451可能通过不同的基因调节机制影响IPC保护心肌I/RI.趋向将miRNA与靶基因、 信号调节通路相结合将是未来研究miRNA调节IPC保护心肌I/RI的重要趋势.     

远隔后处理心肌保护的基础研究和临床应用转化

背景 在远离靶器官的组织(如肢体)实施后处理产生保护性信号(即远隔后处理)是提供内源性组织保护的一种措施.目的 综述远隔后处理的心肌保护效应、作用机制和临床应用转化现状.内容 在包括鼠、兔和猪在内的多个种属动物实验研究中,远隔后处理能够明显减轻心肌缺血/再灌注(ischemia/reperfusion,I/R)损伤、组织坏死和细胞凋亡.与远隔预处理一样,远隔后处理需要通过体液或神经信号转导通路传递或交流保护性因子或信号.靶器官保护机制的触发子包括G蛋白耦联受体配体、缺血代谢物和小分子热敏物质.有关远隔后处理改善临床结果或生物标记的临床研究结果令人鼓舞.趋向 与经典缺血预处理和后处理不同,有关远隔后处理心肌保护作用生理或分子机制的研究目前仍显不足.如果进一步的临床研究证实远隔后处理可改善患者的转归,其实践价值将是巨大的.     

红细胞生成素在脊髓损伤中抑制细胞凋亡的作用

红细胞生成素(erythropoietin;EPO)是细胞因子超家族的成员之一,除具有促进祖红细胞的增生、分化和成熟的功能外,还具有抗血管痉挛、抗凋亡和抗炎等多种功能。EPO及其受体不仅存在于造血系统中,还存在于中枢和周围神经系统中,EPO除对多种原因引起的脑损伤具有保护作用外,对急性脊髓损伤及其继发性损伤也具有保护作用。近期研究发现其中最主要的保护机制是抑制细胞的凋亡。目前研究认为,抑制神经元细胞凋亡是EPO短期神经保护作用的基础,而EPO的神经营养作用则具有长期保护效果。但其抑制细胞凋亡的细胞内信号传导途径、对神经细胞的营养作用需要进一步的研究。     

Erythropoietin‐mediated protection in kidney transplantation: nonerythropoietic EPO derivatives improve function without increasing risk of cardiovascular events

The protective, nonerythropoietic effects of erythropoietin (EPO) have become evident in preclinical models in renal ischaemia/reperfusion injury and kidney transplantation. However, four recently published clinical trials using high‐dose EPO treatment following renal transplantation did not reveal any protective effect for short‐term renal function and even reported an increased risk of thrombosis. This review focusses on the current status of protective pathways mediated by EPO, the safety concerns using high EPO dosage and discusses the discrepancies between pre‐clinical and clinical studies. The protective effects are mediated by binding of EPO to a heteromeric receptor complex consisting of two β‐common receptors and two EPO receptors. An important role for the activation of endothelial nitric oxide synthase is proposed. EPO‐mediated cytoprotection still has enormous potential. However, only nonerythropoietic EPO derivatives may induce protection without increasing the risk of cardiovascular events. In preclinical models, nonerythropoietic EPO derivatives, such as carbamoylated EPO and ARA290, have been tested. These EPO derivatives improve renal function and do not affect erythropoiesis. Therefore, nonerythropoietic EPO derivatives may be able to render EPO‐mediated cytoprotection useful and beneficial for clinical transplantation.     

Erythropoietin and progression of CKD

In patients with primary as well as secondary chronic kidney disease (CKD), anemia has been identified as an independent risk factor for progression. In these patients anemia is thought to be a surrogate parameter for tissue hypoxia that perpetuates preexisting renal tissue injury, and treatment of anemia with recombinant human erythropoietin (rHuEPO) was therefore expected to retard progression. However, results of recently published large trials in patients with CKD did not fulfill these expectations. The reason for the discrepant findings may be distinct molecular pathways and/or EPO tissue receptor affinities that mediate the effect of EPO on erythropoiesis and tissue protection by EPO. A pivotal intracellular pathway is the activation of Akt (i.e., serine/threonine protein kinase B), but further potential pathways have been identified that may play an important role in tissue protection. In this study, we review data on the non-hematological effects of rHuEPO in different experimental settings of acute and chronic kidney injury, and discuss clinical renoprotective strategies with rHuEPO or analogue substances that are not related to anemia correction.     

Kardiale Protektion und Regeneration

Erythropoietin (EPO) is a hypoxia-inducible growth factor with a pleiotropic profile. Following myocardial ischemia, EPO-mediated main effects include inhibition of apoptosis, modification of inflammation, angiogenesis, and reverse remodeling. Furthermore, synergism with stem cell-related cardiac repair and the induction of intracardiac proliferation might exert therapeutic potency. As a result of repeated reports of therapeutic efficiency, EPO has increasingly been the focus of clinical interest. Possible indications, translational guidelines, and risks during preclinical and clinical trials are summarized. Dosing, timing, and routes of application as well as EPO derivatives were evaluated using the data from a systematic review (database: Medline) and our own investigations.     

The brain erythropoietin system and its potential for therapeutic exploitation in brain disease

The discovery of the broad neuroprotective potential of erythropoietin (EPO), an endogenous hematopoietic growth factor, has opened new therapeutic avenues in the treatment of brain diseases. EPO expression in the brain is induced by hypoxia. Practically all brain cells are capable of production and release of EPO and expression of its receptor. EPO exerts multifaceted protective effects on brain cells. It protects neuronal cells from noxious stimuli such as hypoxia, excess glutamate, serum deprivation or kainic acid exposure in vitro by targeting a variety of mechanisms and involves neuronal, glial and endothelial cell functions. In rodent models of ischemic stroke, EPO reduces infarct volume and improves functional outcome, but beneficial effects have also been observed in animal models of subarachnoid hemorrhage, intracerebral hemorrhage, traumatic brain injury, and spinal cord injury. EPO has a convenient therapeutic window upon ischemic stroke and favorable pharmacokinetics. Results from first therapeutic trials in humans are promising, but will need to be validated in larger trials. The safety profile and effectiveness of EPO in a wide variety of neurologic disease models make EPO a candidate compound for a potential first-line therapeutic for neurologic emergencies.     

A role for erythropoietin in the attenuation of radiocontrast-induced acute renal failure in rats

BACKGROUND: Radiocontrast-induced nephropathy (CIN) remains an important iatrogenic cause of acute renal failure in high-risk patients, despite the development of safer contrast media, the improvement of hydration protocols, and the introduction of additional preventive strategies. Erythropoietin (EPO) pretreatment may confer protection against acute renal failure through the induction of stress response genes. METHODS: The effect of EPO has been evaluated in a rat model of CIN, induced by iothalamate, following the inhibition of nitric oxide- and prostaglandin-synthesis with indomethacin and N(omega) nitro-L-arginine methyl ester (L-NAME). Twenty-two male Sprague-Dawley rats were subjected to saline (CTR) or EPO injections (3000 U/kg and 600 U/kg, 24 and 2 h before the induction of CIN, respectively). RESULTS: The decline in creatinine clearance in CTR animals from 0.38 +/- 0.03 to 0.28 +/- 0.03 mL/min/100 g (p < 0.005), was prevented by EPO pretreatment (from 0.34 +/- 0.02 to 0.32 +/- 0.03 mL/min/100 g, NS). The extent of medullary thick ascending limb- and S3-tubular damage in the outer medulla, however, was comparable in the two experimental groups. CONCLUSIONS: EPO pretreatment prevents renal dysfunction in a rat model of CIN. Further experimental and clinical studies are required to confirm these preliminary conclusions regarding a potential protective potency of EPO against CIN.     

Cardioprotection

The demographic change is associated with an increasing number of elderly patients with serious comorbidities. The prevalence of coronary heart disease in particular increases with age and raises the risk of perioperative myocardial ischemia. In the last few years various interventions have been evaluated to lower the perioperative risk for serious cardiovascular events. This includes cardioprotective medical interventions, for example with β-receptor blockers and statins. Current guidelines recommend that patients who are on β-receptor blockers or statins for chronic treatment of cardiovascular diseases should continue this medication throughout the perioperative period. Myocardial conditioning has been assessed to be effective under numerous experimental conditions and clinical trials have also provided evidence for myocardial protection by conditioning. Besides ischemic and anesthetic-induced preconditioning the noninvasive technique of remote preconditioning offers interesting possibilities, especially for patients with serious comorbidities; however, large scale randomized clinical multicentre trials are still needed. Regarding cardioprotective effectiveness, the clinical data for regional anesthesia are very heterogeneous; nevertheless regional anesthesia is very effective in postoperative pain therapy. Therefore regional anesthesia should be used as a part of multimodal therapy concepts to lower the risk of perioperative cardiovascular events.     

Kardioprotektion

The demographic change is associated with an increasing number of elderly patients with serious comorbidities. The prevalence of coronary heart disease in particular increases with age and raises the risk of perioperative myocardial ischemia. In the last few years various interventions have been evaluated to lower the perioperative risk for serious cardiovascular events. This includes cardioprotective medical interventions, for example with ??-receptor blockers and statins. Current guidelines recommend that patients who are on ??-receptor blockers or statins for chronic treatment of cardiovascular diseases should continue this medication throughout the perioperative period. Myocardial conditioning has been assessed to be effective under numerous experimental conditions and clinical trials have also provided evidence for myocardial protection by conditioning. Besides ischemic and anesthetic-induced preconditioning the noninvasive technique of remote preconditioning offers interesting possibilities, especially for patients with serious comorbidities; however, large scale randomized clinical multicentre trials are still needed. Regarding cardioprotective effectiveness, the clinical data for regional anesthesia are very heterogeneous; nevertheless regional anesthesia is very effective in postoperative pain therapy. Therefore regional anesthesia should be used as a part of multimodal therapy concepts to lower the risk of perioperative cardiovascular events.     

Remote ischemic preconditioning in major vascular surgery

Remote ischemic preconditioning is a physiologic mechanism in mammalian species whereby brief exposure to nonlethal ischemia in one tissue confers protection against a prolonged ischemic insult in a distant tissue. First described almost 15 years ago, it has been slow to translate into clinical practice. Several clinical trials have recently reported that remote ischemic preconditioning reduces myocardial injury after major cardiovascular surgery. In addition, a randomized trial in patients undergoing open abdominal aortic aneurysm repair reported a significant reduction in perioperative myocardial infarctions. Remote ischemic preconditioning is easily performed and likely to prove highly cost-effective. large-scale trials of the technique are warranted in patients undergoing major vascular surgery.     

Erythropoietin ameliorates renal dysfunction during endotoxaemia.

BACKGROUND: Sepsis has a high mortality (50-80%) when associated with acute renal failure (ARF). Oxidant injury and proinflammatory cytokines and chemokines have been shown to increase with endotoxaemia-related ARF. Since erythropoietin (EPO) has been demonstrated to possess anti-oxidant and anti-inflammatory properties, EPO may have therapeutic efficacy for treating ARF associated with endotoxaemia. METHODS: Wild-type mice were given 2.5 mg/kg of intraperitoneal (i.p.) endotoxin, lipopolysaccharide (LPS), and studied 16 h later. Thirty minutes prior to LPS, the mice were given either EPO or vehicle. RESULTS: During endotoxaemia, EPO was found to significantly attenuate the renal dysfunction, as assessed by glomerular filtration rate (48.1 +/- 12.4 microl/min vs 136.7 +/- 30.2, P < 0.05). Renal blood flow and mean arterial pressure were not significantly different between the two groups. The renal dysfunction during endotoxaemia was associated with a decrease in renal superoxide dismutase (SOD). The EPO-related renal protection was associated with reversal of the effects of endotoxin on renal SOD. CONCLUSION: This is the first demonstration of a renal protective effect of EPO on endotoxin-related renal dysfunction.