Collateral lessons from recent acute ischemic stroke trials

Abstract

Numerous acute ischemic stroke trials have recently published detailed results, providing an opportunity to consider the role of collaterals in stroke pathophysiology and their influential effect on patient outcomes. Safety and Efficacy of NeuroFlo Technology in Ischemic Stroke (SENTIS), the largest randomized controlled trial of device therapy to date, tested the potential augmentation of collateral perfusion. SYNTHESIS Expansion, Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE), and Interventional Management of Stroke (IMS) III chronicled the saga of endovascular therapy trialed against medical treatment for acute ischemic stroke. These recent randomized studies, however, largely neglect current device technology available for endovascular therapy as advanced by the TREVO2 and SOLITAIRE?^TM FR With the Intention For Thrombectomy (SWIFT) studies. Such exhaustive efforts in recent trials have failed to introduce a new treatment for stroke that unequivocally improves patient outcomes. Collateral perfusion is widely recognized to vary across individuals in any population and exerts a dramatic effect on baseline variables including the time course of ischemic injury, stroke severity, imaging findings, and therapeutic opportunities. Similarly, collaterals have been recognized to influence recanalization, reperfusion, hemorrhagic transformation, and subsequent neurological outcomes after stroke. Collateral lessons may be gleaned from these trials, to expand consideration of overall study results and perhaps most importantly, alter ongoing and new trials in development. Detailed analyses of available information on collaterals from these trials demonstrate that collaterals may be more influential than the choice of treatment modality or intervention.     

The monoacylglycerol lipase inhibitor JZL184 is neuroprotective and alters glial cell phenotype in the chronic MPTP mouse model

Changes in cannabinoid receptor expression and concentration of endocannabinoids have been described in Parkinson's disease; however, it remains unclear whether they contribute to, or result from, the disease process. To evaluate whether targeting the endocannabinoid system could provide potential benefits in the treatment of the disease, the effect of a monoacylglycerol lipase inhibitor that prevents degradation of 2-arachidonyl-glycerol was tested in mice treated chronically with probenecid and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTPp). Chronic administration of the compound, JZL184 (8 mg/kg), prevented MPTPp-induced motor impairment and preserved the nigrostriatal pathway. Furthermore, none of the hypokinetic effects associated with cannabinoid receptor agonism were observed. In the striatum and substantia nigra pars compacta, MPTPp animals treated with JZL184 exhibited astroglial and microglial phenotypic changes that were accompanied by increases in TGFβ messenger RNA expression and in glial cell-derived neurotrophic factor messenger RNA and protein levels. JZL184 induced an increase in β-catenin translocation to the nucleus, implicating the Wnt/catenin pathway. Together, these results demonstrate a potent neuroprotective effect of JZL184 on the nigrostriatal pathway of parkinsonian animals, likely involving restorative astroglia and microglia activation and the release of neuroprotective and antiinflammatory molecules.     

大鼠脑缺血损伤后锂盐治疗对海马CA1区的影响

目的探讨大鼠局灶脑缺血损伤后锂盐治疗对海马CA1神经元形态学变化的影响。方法将SD大鼠随机分为假手术组(SH组)、缺血-再灌注组(IR组)和缺血损伤后氯化锂治疗组(LI组),按处死时间不同,将各组再分为三个亚组:SH1d、SH2d、SH3d组;IR1dI、R2dI、R3d组;LI1d、LI2d、LI3d组。线栓法制作大鼠大脑中动脉闭塞(MCAO)局灶脑缺血模型,1.5 h后再灌注。LI组于脑缺血后1 h,氯化锂(3 mmol/kg)腹腔注射,每天一次至处死。SH组和IR组以生理盐水替代。HE染色比较各组缺血损伤后1、2、3 d海马CA1区神经元损伤程度。结果虽然LI组与IR组的CA1区存活锥体细胞数存在类似下降趋势,但LI2d组、LI3d组分别较IR2d组I、R3d组存活锥体细胞数明显增多(P<0.01)。结论大鼠局灶脑缺血后氯化锂的治疗能减轻海马神经元的损伤程度。     

CDP-c、硫酸镁联用对大鼠短暂脑缺血的神经保护作用

目的 研究胞二磷胆碱（CDP-c）、硫酸镁联用对大鼠试验性短暂局灶脑缺血的神经保护作用.方法 用大脑中动脉栓塞（MCAO）法制作短暂性（90min）局部脑缺血模型,观察CDP-c、硫酸镁单用及不同剂量联用7d后,Caspase-3阳性细胞数、神经功能缺损及脑梗死体积的变化.结果 和对照组相比,CDP-c、硫酸镁单用及两药联用组脑梗死体积较小,Caspase-3表达细胞数较少,并有统计学意义.两药联用组脑梗死体积均比单用组小,Caspase-3表达细胞数亦较两药单用组少（P＜0.05）.两药联用组相比各项指标均无显著意义（P＞0.05）.结论 CDP-c和硫酸镁单用对试验性短暂脑缺血模型可能具有神经保护作用.CDP-c与硫酸镁合用对短暂性试验性局灶脑缺血的神经保护可能有协同作用,并且可以减少各药的用量.     

Therapeutic effects of stiripentol against ischemia-reperfusion injury in gerbils focusing on cognitive deficit,neuronal death,astrocyte damage and blood brain barrier leakage in the hippocampus

Stiripentol is an anti-epileptic drug for the treating of refractory status epilepticus. It has been reported that stiripentol can attenuate seizure severity and reduce seizure-induced neuronal damage in animal models of epilepsy. The objective of the present study was to investigate effects of post-treatment with stiripentol on cognitive deficit and neuronal damage in the cornu ammonis 1 (CA1) region of the hippocampus proper following transient ischemia in the forebrain of gerbils. To evaluate ischemia-induced cognitive impairments, passive avoidance test and 8-arm radial maze test were performed. It was found that post-treatment with stiripentol at 20 mg/kg, but not 10 or 15 mg/kg, reduced ischemia-induced memory impairment. Transient ischemia-induced neuronal death in the CA1 region was also significantly attenuated only by 20 mg/kg stiripentol treatment after transient ischemia. In addition, 20 mg/kg stiripentol treatment significantly decreased ischemia-induced astrocyte damage and immunoglobulin G leakage. In brief, stiripentol treatment after transient ischemia ameliorated transient ischemia-induced cognitive impairment in gerbils, showing that pyramidal neurons were protected and astrocyte damage and blood brain barrier leakage were significantly attenuated in the hippocampus. Results of this study suggest stiripentol can be developed as a candidate of therapeutic drug for ischemic stroke.     

基于PI3K/Akt通路探讨氯吡格雷对脑缺血再灌注损伤大鼠的神经保护作用

目的基于磷酯酰激醇3-激酶/蛋白激酶B(PI3K/Akt)通路探讨氯吡格雷对脑缺血再灌注损伤大鼠的神经保护作用.方法建立脑缺血再灌注大鼠模型,随机分为模型组、氯吡格雷组、LY294002(PI3K抑制剂)组、氯吡格雷+LY294002组,每组12只,另取12只SD大鼠设为假手术组.分组处理后,所有大鼠进行神经功能缺损评分并尾静脉取血,处死大鼠,HE染色检测各组大鼠神经元病理情况;三苯基氯化四氮唑(TTC)染色检测各组大鼠脑组织梗死面积;ELISA检测血清中中枢神经特异性蛋白(S100β)、神经元特异性烯醇化酶(NSE)、白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)水平;蛋白免疫印迹法检测脑组织中PI3K/Akt通路蛋白表达情况.结果与假手术组相比,模型组大鼠脑组织神经元出现坏死、核收缩变小等病理变化,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均明显升高(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt明显降低(P<0.05);与模型组相比,氯吡格雷组大鼠神经元病理损伤减轻,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均降低(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt升高(P<0.05);LY294002组大鼠神经元病理损伤加重,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均升高(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt降低(P<0.05).与LY294002组相比,氯吡格雷+LY294002组大鼠神经元病理损伤减轻,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均降低(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt升高(P<0.05).与氯吡格雷组相比,氯吡格雷+LY294002组大鼠神经元病理损伤加重,神经功能缺损评分、脑梗死面积、血清中S100β、NSE、IL-6及TNF-α水平均升高(P<0.05),脑组织中p-PI3K/PI3K、p-Akt/Akt降低(P<0.05).结论氯吡格雷可通过激活PI3K/Akt通路减轻大鼠脑缺血再灌注损伤,保护脑组织.     

JAK2-STAT3信号通路在树鼩脑缺血后适应中的作用机制

 目的：观察JAK2-STAT3信号转导通路在树鼩缺血后适应（ischemic postconditioning,IPoC）神经保护中的调控作用,探讨阻断JAK2-STAT3通路后脑损伤加重的机制。方法：通过光化学反应建立树鼩血栓性脑缺血模型;于缺血后4 h夹闭患侧颈总动脉3次（每次5 min）实施IPoC。于IPoC前10 min侧脑室注射AG490（JAK2抑制剂）后,采用TTC染色观察树鼩脑梗死面积的变化,通过HE染色和电镜观察脑皮层神经元形态改变及超微结构变化,应用Western blot检测IPoC及AG490处理后皮层t-STAT3和p-STAT3蛋白水平的变化。结果：缺血24 h,皮层神经元固缩,线粒体肿胀,嵴溶解;脑梗死面积占半脑面积的（24.78±3.30）%;此时皮层神经元STAT3磷酸化水平明显增高（P<0.01）。IPoC后皮层神经元损伤减轻,线粒体肿胀改善,脑梗死面积占半脑面积的百分比减小为（17.67±1.83）%（P<0.01）,STAT3磷酸化水平进一步增高（P<0.01）。然而,给予AG490处理后,皮层神经元损伤加重,脑梗死面积再次增大为（23.85±2.77）%（P<0.05）,STAT3磷酸化水平则明显降低（P<0.05）。结论：IPoC可能通过调控STAT3的磷酸化而减轻树鼩缺血性脑损伤,抑制JAK2-STAT3信号通路可抵消IPoC的保护效应而加重脑损伤。     

缺血后适应对树鼩脑缺血信号转导及转录激活因子3过磷酸化的调控作用

目的观察信号转导及转录激活因子3(STAT3)磷酸化在树鼩脑缺血后适应(PC)神经保护中的作用,并探讨其可能机制。方法将50只健康成年树鼩随机分为对照组、脑缺血4 h组、脑缺血24 h组、后适应4 h组和后适应24 h组(每组n=5),其中10只动物做HE染色(n=5)及电子显微镜观察(n=5)。本实验通过光化学反应建立树鼩血栓性脑缺血模型;于缺血后4 h夹闭患侧颈总动脉3次(每次5 min)实施缺血PC。采用TTC染色观察树鼩脑梗死面积的变化,通过HE和电子显微镜观察脑皮质和海马组织学改变及其超微结构变化,应用Western blotting检测皮层总STAT3(t-STAT3)及磷酸化STAT3(p-STAT3)蛋白表达变化。结果脑缺血后皮层血管内皮细胞肿胀,皮层及海马神经元损伤,线粒体肿胀、嵴溶解,以缺血24 h损伤最为明显,脑梗死面积达到(24.78±2.06)%。而皮层p-STAT3蛋白表达随缺血时间延长呈增高趋势,缺血4 h p-STAT3蛋白表达明显增高(0.24±0.1,P<0.01),缺血24 h p-STAT3蛋白表达则持续增高(0.32±0.1,P<0.01)。缺血PC处理后皮层血管内皮细胞水肿好转,皮层及海马神经元损伤减轻,脑梗死面积减小为(17.67±1.90)%(P<0.01)。与缺血组相比,缺血PC 4 h p-STAT3蛋白表达进一步升高(0.41±0.09,P<0.01),缺血PC 24 h p-STAT3蛋白表达增高更加显著(0.70±0.11,P<0.01)。结论树鼩脑缺血可导致STAT3磷酸化代偿性增强,缺血PC的脑保护作用可能与其促进STAT3过磷酸化有关。     

Aβ induces its own prion protein N-terminal fragment (PrPN1)–mediated neutralization in amorphous aggregates

Plasma membrane cellular prion protein (PrP^C) is a high-affinity receptor for toxic soluble amyloid-β (Aβ) oligomers that mediates synaptic dysfunction. Secreted forms of PrP^C resulting from PrP^C α-cleavage (PrPN1) or shedding (shed PrP^C) display neuroprotective activity in neuronal cultures and in mouse models of Aβ-induced neuronal dysfunction. In vitro, recombinant PrPN1 and PrP inhibit Aβ fibrillization. However, the mechanism by which PrPN1 and shed PrP^C neutralize Aβ oligomers is unclear, and evidence of such neuroprotective activity in Alzheimer's disease (AD) patients is lacking. Here, we show that PrPN1 association with Aβ causes a conformational change resulting in the formation of amorphous and insoluble aggregates that are not compatible with the assembly of Aβs. Using postmortem brain tissues of AD patients, we were able to coimmunoprecipitate Aβ with PrP^C molecules and observed a coaggregation of Aβ and PrPN1 in the guanidine-extractable fraction presumably representing insoluble amyloid plaques. Furthermore, PrP^C α-cleavage is increased in AD brains, and we noticed a significant positive correlation between the levels of α-cleavage and of guanidine-extractable Aβ. These data strongly support the hypothesis that PrP^C α-cleavage is an endogenous neuroprotective mechanism in AD and support the development of PrP^C-derived peptides as therapeutic molecules for AD.