脊髓继发性损伤中自噬和凋亡相互调节的研究现状

脊髓损伤是脊柱外科的常见病,包括原发性损伤和继发性损伤。脊髓原发性损伤在受伤后立刻发生,且神经细胞不可再生,所以阐明脊髓继发性损伤的具体分子机制,有利于探索脊髓损伤的治疗方案。目前,自噬对脊髓损伤预后的作用仍有很大争议,甚至不同研究得出完全相反的结论。这可能是由于自噬能清除细胞内受损的蛋白质和细胞器,而蛋白质和细胞器对细胞存活具有重要作用。自噬、凋亡常共同存在,相互作用,共同调节脊髓损伤。本综述总结了自噬、凋亡在脊髓继发性损伤中的相互调节机制,以期为进一步研究提供参考。     

自噬在吉西他滨诱导胰腺癌细胞凋亡中的作用

目的:研究自噬在吉西他滨(gemcitabine,Gem)诱导胰腺癌细胞SW1990凋亡中的作用,并以氯喹特异性抑制自噬,以探讨其可能机制。方法:采用CCK8法检测Gem对胰腺癌细胞增殖的影响,并用实时定量PCR检测自噬相关基因LC3的表达,以p62免疫荧光染色检测细胞内自噬泡,通过Western印迹法检测自噬相关蛋白LC3、Beclin 1的表达,并用AnnexinⅤ/PI流式细胞方法检测Gem诱导后细胞凋亡的变化。进一步通过氯喹抑制自噬,检测自噬抑制前后细胞增殖、自噬及凋亡的变化。结果:Gem对胰腺癌细胞SW1990增殖具有部分抑制作用,Gem作用能迅速激活细胞自噬从而产生耐药。LC3的mRNA表达升高1.4~2.2倍(P<0.05),LC3-Ⅱ蛋白水平升高1.5~2.7倍(P<0.05)。Gem和氯喹联合用药组较Gem单药组细胞凋亡蛋白Caspase-3表达升高,细胞存活率从64.3%±3.1%降低为35.2%±3.4%(P<0.05)。结论:自噬在Gem诱导胰腺癌细胞凋亡的过程中可能起到保护作用,氯喹抑制自噬后可增强Gem的促凋亡作用。     

蛋白激酶Cδ通过抑制自噬促进TRAIL诱导前列腺癌细胞凋亡

目的探讨蛋白激酶Cδ在去势抵抗性前列腺癌细胞中对自噬的影响,并研究其相关机制。方法使用去势抵抗性前列腺癌细胞C4-2和CWR22Rv1作为研究对象,将细胞进行分组,分别使用DMSO对照、BAF-A1、TRAIL、PKCδ激活剂PMA和PKCδ抑制剂rottlerin对细胞进行处理。用MTT检测各组药物处理后细胞存活状况;用Western blot检测各组药物处理后mTOR通路、自噬相关蛋白和凋亡相关蛋白的变化;用GFP-LC3荧光蛋白标记检测细胞内自噬作用的变化。结果 TRAIL诱导去势抵抗性前列腺癌细胞C4-2和CWR22Rv1自噬作用增强。PMA可以通过激活mTOR通路抑制自噬并提高细胞对TRAIL的凋亡敏感性。PKCδ在此过程中是抑制自噬作用的关键分子。结论本研究证实在去势抵抗性前列腺癌细胞C4-2和CWR22Rv1中,PKCδ/AKT/mTOR通路对细胞自噬的负向调节作用,激活该通路可以促进TRAIL诱导的细胞凋亡现象。     

HO-1对醋酸铅诱导肾小管上皮细胞氧化应激的保护机制

目的:探讨血红素氧合酶-1(HO-1)对醋酸铅(LA)诱导的肾小管上皮细胞损伤的保护机制,为铅性肾病的治疗提供一定的理论依据。方法:采用醋酸铅孵育人肾小管上皮细胞48 h建立细胞损伤模型,原卟啉氯化钴(Co PP)诱导HO-1表达,自噬抑制剂(3-MA)抑制自噬,CCK-8方法检测细胞活性;流式细胞术检测细胞凋亡率; Western blot检测自噬标志蛋白LC3Ⅱ/LC3Ⅰ、p62及氧化应激相关蛋白超氧化物歧化酶(SOD2)、过氧化氢酶(CAT)、丙二醛(MDA)含量。结果:醋酸铅处理48 h后细胞活性、HO-1及自噬水平较Control组均明显下降,在补充Copp激活HO-1后细胞自噬水平上升,细胞活性明显恢复; Copp可明显改善细胞抗氧化酶CAT、SOD2表达,降低MDA,降低细胞凋亡率; 3-MA抑制自噬导致细胞CAT、SOD2表达进一步降低,MDA含量增加,细胞凋亡率升高,并且补充Copp后细胞CAT和MDA水平仅部分改善,SOD2表达未见明显恢复,提示抑制自噬减弱了HO-1的抗氧化作用。结论:HO-1可通过上调自噬减轻醋酸铅诱导的肾小管上皮细胞氧化应激损伤,减少细胞凋亡,HO-1可能可以作为治疗铅性肾病的一个干预靶点。     

自噬及其在中枢神经系统损伤修复中作用的研究进展

近年来自噬在脑损伤如脑缺血、脑外伤等方面有较多研究,但在脊髓损伤方面却刚刚起步。笔者对中枢神经系统损伤修复中自噬的主要调节机制、自噬与凋亡关系以及自噬与脑损伤、脊髓损伤关系的研究进展进行综述,以期为今后更加深入探索自噬在中枢神经系统损伤尤其是脊髓损伤中的作用提供参考。     

脊髓损伤中钙蛋白酶的作用

脊髓损伤后可发生不同程度的神经坏死和组织变性,导致脊髓神经功能障碍。脊髓继发性损伤过程中钙蛋白酶(calpain)在脊髓损伤中发挥重要作用。Calpain为一Ca2+依赖性半胱氨酸蛋白酶,该酶包括2种同分异构体μ-calpain和m-calpain,分别由微摩尔和毫摩尔浓度的Ca2+激活。细胞内calpain以非活性酶原形式存在,细胞内游离Ca2+浓度升高后,calpain酶原被活化,引起calpain活化后一系列分子生物化学的改变,在脊髓引起细胞凋亡或损伤。应用calpain的特异性抑制剂进行干预后,脊髓calpain的表达和活性受到抑制,脊髓的病理改变和细胞凋亡得到缓解,神经功能得以保护。该文将calpain在脊髓损伤发展过程中的作用作一综述。     

环孢素A在急性脊髓损伤中的作用与研究进展

环孢素A(cyclosporine A,CsA)作为免疫抑制剂在器官移植患者中广泛应用,最近的研究表明在急性脊髓损伤中,CsA能发挥明确的神经保护作用,其主要机制是通过抑制损伤脊髓的脂质过氧化反应、抗细胞凋亡、阻断小神经胶质细胞的激活、神经营养、抗炎、促进轴突再生等发挥神经保护作用.     

细胞自噬与骨关节炎软骨退变

软骨细胞能感受关节内微环境变化而作出应答,以调整细胞基质代谢,维持关节软骨生物学功能。软骨细胞所处低氧环境是引起细胞自噬的重要因素。细胞自噬不同于细胞凋亡和细胞坏死,可调节软骨细胞适应低氧环境,提高软骨细胞生存能力,可能是阻止或延缓软骨退变的重要机制之一。有效调控细胞自噬、细胞凋亡在骨关节炎形成和发展中的作用,可能对骨关节炎防治研究具有重要意义。     

锂剂治疗脊髓损伤机制的研究进展

脊髓损伤是由一系列内外因素所造成的骨科及神经科学领域严重的致残性疾病,是目前医学界的一大难题.锂剂作为治疗双相情感障碍的主要药物已有100多年的历史.研究证实锂剂对脑神经元有保护作用,其对脊髓损伤的治疗作用也渐渐被观察到.锂剂能够通过保护神经元完整、减少损伤后炎症反应、促进神经营养因子的生成和释放、刺激神经发生以及促进自噬、抑制凋亡等机制达到治疗脊髓损伤的目的.通过回顾有关锂剂对神经系统作用的研究,总结分析了锂剂治疗脊髓损伤作用机制的研究进展,以锂剂为基础的综合治疗具有良好的应用前景.     

线粒体自噬在肾缺血-再灌注损伤中的作用

线粒体自噬是机体选择性清除受损线粒体的防御性过程,对维持细胞生存有重要意义。一般情况下线粒体自噬阈值较低,当处在能量耗竭、缺血、缺氧等环境中时,线粒体自噬可被激活。肾脏的缺血-再灌注损伤(IRI)是临床中较为常见的病理生理过程,是导致急性肾损伤的主要原因。目前认为IRI与氧化应激、线粒体功能紊乱、自噬和凋亡等密切相关。本文就线粒体自噬的概述、线粒体自噬在肾IRI中的作用以及线粒体自噬的调控进行综述,为临床中防治肾IRI提供新的研究思路。     

Rapamycin promotes autophagy and reduces neural tissue damage and locomotor impairment after spinal cord injury in mice

The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that negatively regulates autophagy. Rapamycin, an inhibitor of mTOR signaling, can promote autophagy and exert neuroprotective effects in several diseases of the central nervous system (CNS). In the present study, we examined whether rapamycin treatment promotes autophagy and reduces neural tissue damage and locomotor impairment after spinal cord injury (SCI) in mice. Our results demonstrated that the administration of rapamycin significantly decreased the phosphorylation of the p70S6K protein and led to higher expression levels of LC3 and Beclin 1 in the injured spinal cord. In addition, neuronal loss and cell death in the injured spinal cord were significantly reduced in the rapamycin-treated mice compared to the vehicle-treated mice. Furthermore, the rapamycin-treated mice showed significantly higher locomotor function in Basso Mouse Scale (BMS) scores than did the vehicle-treated mice. These results indicate that rapamycin promoted autophagy by inhibiting the mTOR signaling pathway, and reduced neural tissue damage and locomotor impairment after SCI. The administration of rapamycin produced a neuroprotective function at the lesion site following SCI. Rapamycin treatment may represent a novel therapeutic strategy after SCI.     

Review of current evidence for apoptosis after spinal cord injury

The initial mechanical tissue disruption of spinal cord injury (SCI) is followed by a period of secondary injury that increases the size of the lesion. The secondary injury has long been thought to be due to the continuation of cellular destruction through necrotic (or passive) cell death. Recent evidence from brain injury and ischemia suggested that cellular apoptosis, an active form of programmed cell death seen during development, could play a role in CNS injury in adulthood. Here, we review the evidence that apoptosis may be important in the pathophysiology of SCI. There is now strong morphological and biochemical evidence from a number of laboratories demonstrating the presence of apoptosis after SCI. Apoptosis occurs in populations of neurons, oligodendrocytes, microglia, and, perhaps, astrocytes. The death of oligodendrocytes in white matter tracts continues for many weeks after injury and may contribute to post-injury demyelination. The mediators of apoptosis after SCI are not well understood, but there is a close relationship between microglia and dying oligodendrocytes, suggesting that microglial activation may be involved. There is also evidence for the activation of important intracellular pathways known to be involved in apoptosis in other cells and systems. For example, some members of the caspase family of cysteine proteases are activated after SCI. It appears that the evolution of the lesion after SCI involves both necrosis and apoptosis. It is likely that better understanding of apoptosis after SCI will lead to novel strategies for therapeutic interventions that can diminish secondary injury.     

大鼠脊髓损伤中的细胞凋亡及甲基强的松龙的干预作用

目的：探讨脊髓损伤（SCI）继发损伤机制,研究损伤脊髓细胞的凋亡及其意义,观察甲基强的松龙（MP）对细胞凋亡的影响。方法：使用改良Allen法制作大鼠急性SCI模型,实验分3组,假损伤（脊髓未受打击）,损伤组及MP治疗组,采用HE,荧光Hoechst 33342,TUNEL(末端脱氧核苷转移酶介导的脱氧尿苷三磷酸生物素缺口末端标记技术）等技术观察SCI后4h,8h,3d,7d,14d,21d及28d时损伤中心及邻近节段脊髓细胞的凋亡,治疗组损伤后30min给予大剂量MP,比较MP治疗组与损伤组脊髓细胞凋亡的变化,同时平行观察大鼠神经学和组织学恢复情况及两组神经丝蛋白（NF）含量的变化。结果：假损伤组各检测方法未见脊髓细胞凋亡,损伤组大鼠急性SCI后1d开始出现脊髓细胞凋亡,3d达高峰,自损伤中心向头尾端递减分布,持续21d,MP治疗组在伤后3d及7d凋亡脊髓细胞较损伤组显著减少,神经学恢复及组织学评分较损伤组有显著性提高,结论：凋亡是SCI后脊髓神经元死亡的一种重要方式,在继发性损伤中起极为重要的作用。MP的治疗作用可能与其干预SCI后细胞凋亡有关。     

Overexpression of SOD1 in transgenic rats attenuates nuclear translocation of endonuclease G and apoptosis after spinal cord injury

Spinal motor neurons are selectively vulnerable after spinal cord injury (SCI). Recent studies suggest they undergo apoptosis after caspase activation through a mitochondria-dependent apoptosis pathway, and that oxidative stress after SCI is likely to play a role. However, other signaling pathways of apoptosis that involve mitochondria have not been thoroughly studied after SCI. Apoptosis-inducing factor (AIF) and endonuclease G (EndoG) are mitochondrial apoptogenic proteins that are capable of inducing neuronal apoptosis when translocated from mitochondria to nuclei through a caspase-independent pathway. In this study, we examined translocation of these proteins and apoptotic cell death of motor neurons. The role of oxidative stress was also studied using transgenic (Tg) rats that overexpress the intrinsic antioxidant copper/zinc-superoxide dismutase (SOD1). Western blots and an activity assay demonstrated that a greater amount of SOD1 and higher activity of SOD presented in mitochondria of Tg rats compared with wild-type (Wt) rats. Immunohistochemistry and Western blots showed translocation of EndoG and AIF from mitochondria to nuclei in motor neurons 1 day after SCI in both groups of rats. However, there was significantly less translocation of EndoG in the Tg rats compared with the Wt rats. Less apoptotic cell death was detected in the Tg rats than in the Wt rats 3 days after SCI. These results suggest that translocation of EndoG and AIF from mitochondria to nuclei may initiate a caspase-independent pathway of apoptosis. An increased level of SOD1 in mitochondria conceivably reduces oxidative stress, thereby attenuating EndoG translocation, and resulting in reduction of caspase-independent apoptosis.     

The role of excitotoxicity in secondary mechanisms of spinal cord injury: a review with an emphasis on the implications for white matter degeneration

Following an initial impact after spinal cord injury (SCI), there is a cascade of downstream events termed 'secondary injury', which culminate in progressive degenerative events in the spinal cord. These secondary injury mechanisms include, but are not limited to, ischemia, inflammation, free radical-induced cell death, glutamate excitotoxicity, cytoskeletal degradation and induction of extrinsic and intrinsic apoptotic pathways. There is emerging evidence that glutamate excitotoxicity plays a key role not only in neuronal cell death but also in delayed posttraumatic spinal cord white matter degeneration. Importantly however, the differences in cellular composition and expression of specific types of glutamate receptors in grey versus white matter require a compartmentalized approach to understand the mechanisms of secondary injury after SCI. This review examines mechanisms of secondary white matter injury with particular emphasis on glutamate excitotoxicity and the potential link of this mechanism to apoptosis. Recent studies have provided new insights into the mechanisms of glutamate release and its potential targets, as well as the downstream pathways associated with glutamate receptor activation in specific types of cells. Evidence from molecular and functional expression of glutamatergic AMPA receptors in white matter glia (and possibly axons), the protective effects of AMPA/kainate antagonists in posttraumatic white matter axonal function, and the vulnerability of oligodendrocytes to excitotoxic cell death suggest that glutamate excitotoxicity is associated with oligodendrocyte apoptosis. The latter mechanism appears key to glutamatergic white matter degeneration after SCI and may represent an attractive therapeutic target.     

FasL, Fas, and death-inducing signaling complex (DISC) proteins are recruited to membrane rafts after spinal cord injury

The Fas/CD95 receptor-ligand system plays an essential role in apoptosis that contributes to secondary damage after spinal cord injury (SCI), but the mechanism regulating the efficiency of FasL/Fas signaling in the central nervous system (CNS) is unknown. Here, FasL/Fas signaling complexes in membrane rafts were investigated in the spinal cord of adult female Fischer rats subjected to moderate cervical SCI and sham operation controls. In sham-operated animals, a portion of FasL, but not Fas was present in membrane rafts. SCI resulted in FasL and Fas translocation into membrane raft microdomains where Fas associates with the adaptor proteins Fas-associated death domain (FADD), caspase-8, cellular FLIP long form (cFLIPL ), and caspase-3, forming a death-inducing signaling complex (DISC). Moreover, SCI induced expression of Fas in clusters around the nucleus in both neurons and astrocytes. The formation of the DISC signaling platform leads to rapid activation of initiator caspase-8 and effector caspase-3, and the modification of signaling intermediates such as FADD and cFLIP(L) . Thus, FasL/Fas-mediated signaling after SCI is similar to Fas expressing Type I cell apoptosis.     

microRNAs在脊髓损伤中的研究进展

脊髓损伤(spinal cord injury,SCI)的继发性病变如氧化应激、凋亡等会进一步加重神经功能损害.microRNAs(miRNAs)是一类新型的小非编码RNAs,其通过沉默翻译或干扰靶mRNAs的表达调控蛋白质的产生和细胞功能.SCI改变了氧化应激、炎症和凋亡等许多继发性损伤相关的miRNAs的表达.本综...     

Neuroprotective effects of recombinant thrombomodulin in controlled contusion spinal cord injury implicates thrombin signaling

Although the central nervous system (CNS) of mammals has had poor prospects for regeneration, recent studies suggest this might improve from blocking "secondary cell loss" or apoptosis. In this regard, intravenous activated protein C (aPC) improved neurologic outcomes in a rat compression spinal cord injury (SCI) model. Protein C activation occurs when the serine protease thrombin binds to the cell surface proteoglycan thrombomodulin (TM) forming a complex that halts coagulation. In culture, rTM blocks thrombin's activation of protease-activated receptors (PARs), that mediate thrombin killing of neurons and glial reactivity. Both PAR1 and prothrombin are rapidly upregulated after contusion SCI in rats, prior to peak apoptosis. We now report neuroprotective effects of intraperitoneal soluble recombinant human rTM on open-field locomotor rating scale (BBB) and spinal cord lesion volume when given 1 h after SCI. BBB scores from four separate experiments showed a 7.6 +/- 1.4 absolute score increase (p < 0.05) at 3 days, that lasted throughout the time course. Histological sections at 14 days were even more dramatic where a twofold reduction in lesion volume was quantified in rTM-treated rats. Thionin staining revealed significant preservation of motor neuronal profiles both at, and two segments below, the lesion epicenter. Activated caspase-3 immunocytochemistry indicated apoptosis was quite prominent in motor neurons in vehicle (saline) controls, but was dramatically reduced by rTM. Microglia, increased and activated after injury, were reduced with rTM treatment. Taken together, these and previous results support a prominent role for coagulation-inflammation signaling cascades in the subacute changes following SCI. They identify a neuroprotective role for rTM by its inhibition of thrombin generation and blockade of PAR activation.     

Role of Rho-associated coiled-coil containing protein kinase in the spinal cord injury induced neuropathic pain

BACKGROUND CONTEXTSpinal cord injury (SCI) can lead to increased phosphorylation of p38 in spinal cord microglia. This is one of the main causes for the development of persistent pain. Recently, we reported our study on the activation of p38 mitogen-activated protein kinases (MAPK) in spinal microglia, which has been considered the key molecule for the onset and maintenance of neuropathic pain after peripheral nerve injury, using a rat model. We also reported that the RhoA/Rho-associated coiled-coil containing protein kinase (ROCK) pathway mediates p38 activation in spinal microglia in peripheral nerve injury. But the precise mechanisms of neuropathic pain induced by SCI are still unclear.PURPOSEThis study aimed to examine the activation of microglia and the p38 MAPK expression in the lumbar spinal cord after thoracic SCI in rats, and the correlation to the therapeutic effect of ROCK inhibitor ripasudil in rats with SCI.STUDY DESIGNMale Sprague–Dawley rats underwent thoracic (T10) spinal cord contusion injury using an Infinite Horizon impactor device. SCI rats received ROCK inhibitor ripasudil (24 nmol/day or 240 nmol/day) from just before SCI to 3 days after SCI.METHODSThe mechanical threshold in the rat's hind paws was measured over four weeks. Morphology of microglia and phosphorylation of p38 (p-p38) in the lumbar spinal cord and were analyzed using immunohistochemistry.RESULTSThe p-p38 positive cell and Iba1 (a maker of microglia) positive area were significantly increased at the lumbar spinal dorsal horn (L4–5) 3 days and 7 days after SCI compared with the sham-control (p<.05), whereas phosphorylated p38 was co-localized with microglia. Three days after SCI, the intensity of phosphorylated p38 and Iba1 immunoreactive cells in the dorsal horn was significantly lower in the ripasudil treated groups than in the saline group. However, administration of ROCK inhibitor did not affect the numbers of microglia. Moreover, the withdrawal threshold of the ripasudil-treated rats was significantly higher than that of the saline-injected rats on 14 days and 28 days after SCI.CONCLUSIONSOur results suggest that activation of ROCK in spinal cord microglia is likely to have an important role in the activation of p38 MAPK, which has been considered as a key molecule that switches on neuropathic pain after SCI. Inhibition of ROCK signaling may offer a means in developing a novel neuropathic pain treatment after SCI. It may help patients with neuropathic pain after SCI.CLINICAL SIGNIFICANCEThe findings in the present study regarding intracellular mechanisms suggest that modulation of ROCK signaling may be a focus for novel treatment for neuropathic pain after SCI.     

Activation of complement pathways after contusion-induced spinal cord injury

Previous studies have shown that a cellular inflammatory response is initiated, and inflammatory cytokines are synthesized, following experimental spinal cord injury (SCI). In the present study, we tested the hypothesis that the complement cascade, a major component of both the innate and adaptive immune response, is also activated following experimental SCI. We investigated the pathways, cellular localization, timecourse, and degree of complement activation in rat spinal cord following acute contusion-induced SCI using the New York University (NYU) weight drop impactor. Mild and severe injuries (12.5 and 50 mm drop heights) at 1, 7, and 42 days post injury time points were evaluated. Classical (C1q and C4), alternative (Factor B) and terminal (C5b-9) complement pathways were strongly activated within 1 day of SCI. Complement protein immunoreactivity was predominantly found in cell types vulnerable to degeneration, neurons and oligodendrocytes, and was not generally observed in inflammatory or astroglial cells. Surprisingly, immunoreactivity for complement proteins was also evident 6 weeks after injury, and complement activation was observed as far as 20 mm rostral to the site of injury. Axonal staining by C1q and Factor B was also observed, suggesting a potential role for the complement cascade in demyelination or axonal degeneration. These data support the hypothesis that complement activation plays a role in SCI.