星形胶质细胞在阿尔茨海默病中的功能变化及分子机制

星形胶质细胞在脑内数量最多,分布最广,对神经元有营养支持的作用,并且能够调控神经元的活性。越来越多的证据表明星形胶质细胞激活参与阿尔茨海默病(Alzheimer's disease,AD)的发生和发展。在AD病理情况下,星形胶质细胞在多种因子如β淀粉样蛋白(beta-amyloid,Aβ)和促炎细胞因子的作用下被激活,激活的星形胶质细胞进一步释放一氧化氮(Nitric oxide,NO)和多种炎性因子增强炎症级联反应。功能失常的星形胶质细胞会促进Aβ的产生,减弱对Aβ的摄取和清除,导致Aβ聚集沉积形成老年斑。激活的星形胶质细胞释放的炎症因子还能显著增加神经元内tau蛋白的异常过度磷酸化,产生神经纤维缠结。本文对星形胶质细胞在AD中参与神经变性的功能变化和分子机制进行总结,为星形胶质细胞作为靶点预防及治疗AD提供一定的理论依据。     

阿尔茨海默病与神经炎症:TNF-α的调控作用

阿尔茨海默病(AD)是一种神经退行性疾病,其相关病变包括淀粉样蛋白β在脑内沉积形成老年斑、过度磷酸化的Tau蛋白在神经细胞内聚集形成的神经原纤维缠结、轴突变性等。越来越多的证据表明, AD的发病机制并不局限于神经元,也与脑组织的神经胶质细胞密切相关。神经胶质细胞中的小胶质细胞和星型胶质细胞在神经炎症过程中发挥多方面的作用,因此影响AD病理变化的发生、发展和转归。小胶质细胞和星型胶质细胞在神经炎症过程中分泌众多细胞因子和趋化因子,其中TNF-α可特异性结合细胞表面受体TNF-R1和TNF-R2,激活NF-κB、JNK(cJun)等信号通路,促进更多炎症细胞因子的表达,参与炎症诱导、细胞凋亡、APP和Tau蛋白的生成等病理过程。该文拟对神经胶质细胞及TNF-α调控神经炎症在阿尔茨海默病中的作用及机制进行综述。     

星形胶质细胞在阿尔茨海默病中的作用及其分子机制

阿尔茨海默病(Alzheimer’s disease,AD)是一种多因素导致的神经退行性疾病。随着社会的老龄化,阿尔茨海默病的发病率呈逐渐上升的趋势,给患者以及社会带来极大的生理痛苦和经济负担。星形胶质细胞在中枢神经系统中数量最多、分布最广,对神经元有营养支持作用,并且还能够调控神经元的活性。在AD的病理情况下,星形胶质细胞能参与Aβ代谢影响老年斑的形成,分泌多种炎症因子和趋化因子参与AD的病理进程,并且还能通过影响突触谷氨酸循环来调节神经元的活性。近年来,星形胶质细胞在AD的病理生理机制中的作用受到越来越多的关注。现就星形胶质细胞在AD发病机制中的作用进行综述。     

综述与专论: 星形胶质细胞对神经退行性疾病影响的研究进展

神经退行性疾病是常见且难以治愈的疾病,给患者的生活带来了极大的不便。星形胶质细胞在神经退行性疾病中发挥重要作用。在神经退行性疾病患者神经系统中,受损的神经胶质细胞对周围的神经元可以产生毒性作用,造成神经元功能障碍,从而死亡。同时,受疾病影响产生的一些反应性星形胶质细胞可以保护神经元,清除神经元周围的有害物质,暂缓疾病的恶化。本综述将讨论星形胶质细胞在部分常见神经退行性疾病中发挥的作用,包括肌萎缩侧索硬化（amyotrophic lateral sclerosis,ALS）、阿尔茨海默病（Alzheimer’s disease,AD）和帕金森病（Parkinson’s disease,PD）。同时总结了星形胶质细胞对这些疾病发挥的共同作用,旨在进一步促进神经退行性疾病的研究进展。     

Abeta-Cu 复合物与Abeta纤丝对小胶质细胞激活作用比较研究

目的：比较具有氧化还原活性的过渡金属离子Cu2+(Cu)诱导形成的A茁聚集物（Aβ-Cu 复合物）与Aβ自聚集形成的纤丝 （Fibrillar Aβ, fAβ）对小胶质细胞激活作用的差异。方法：制备Aβ-Cu复合物和fAβ,利用小鼠BV-2 小胶质细胞株,分别以不同浓 度的Aβ-Cu 复合物和fAβ于37 ℃刺激24 h,检测细胞上清液中的TNF-α（Tumor necrosis factor-α）、NO（Nitric oxide）以及H2O2 （Hydrogen Peroxide）的含量。分别收集Aβ-Cu复合物和fA茁作用24 h 后的大鼠原代小胶质细胞条件培养液,通过观察该条件培 养液对大鼠原代海马神经元细胞活力的影响,评价小胶质细胞介导的间接神经元毒性。结果：（1）在不引起直接神经毒性剂量 （2.5 uM）下,Aβ-Cu 复合物激活小胶质细胞释放TNF-alpha（P<0.01）、NO（P<0.05）以及H2O2（P<0.05）的作用强于fAβ。（2）在此剂量 下,A茁-Cu 复合物通过激活小胶质细胞引起的间接神经元毒性强于fAβ（P<0.05）。结论：与fAβ相比,非神经毒性剂量的Aβ-Cu 复合物对于小胶质细胞具有更强的激活作用,并由此引发更为明显的神经元毒性。     

Aβ25～35诱导大鼠记忆减退与星形胶质细胞及NOS阳性细胞变化

目的探讨Aβ25～35诱导模拟人类Alzheimer`s病(AD)的大鼠病理模型中星形胶质细胞变化与一氧化氮合酶神经元损伤引起的老年性记忆减退之间的关系.方法双侧海马内注射β-淀粉样多肽25～35片段(Aβ25～35)制作大鼠AD模型,注射一周后采用NOS组化染色、GFAP免疫组化染色及NOS组化和GFAP双重染色分析大鼠海马GFAP与NOS的表达.结果海马内注射Aβ25～35后出现海马星形胶质细胞增生、肥大、数目明显多于对照组(P<0.05),并出现一氧化氮阳性星形胶质细胞;海马一氧化氮神经元数量较对照组显著减少(P<0.05).结论 AD模型大鼠学习记忆功能低下与Aβ神经毒性导致NOS阳性神经元损伤、死亡直接相关,反应性星形胶质细胞参与Aβ导致NOS神经元细胞毒性损伤作用,间接导致学习记忆能力减退.     

炎症在阿尔茨海默病中作用机制的研究进展

阿尔茨海默病(Alzheimer’s disease, AD)是一种进行性神经退行性疾病,特征是认知功能下降,主要影响个体的记忆和学习能力。AD发病机制至今尚不明确,主要有β淀粉样蛋白沉积和神经原纤维缠结两大核心病理,这些蛋白质沉积可以通过持续的炎症和氧化应激致神经元功能障碍和细胞死亡,大脑中这种持续的免疫反应已经被认为是其第三大病理特点。胶质细胞的活化、其他免疫细胞的持续激活、炎症因子的产生、部分微RNA表达的上调或下调以及肠道菌群的失调,都可以通过不同的途径产生或促进神经炎症反应,造成神经元损伤,加重AD病理。本文就炎症相关的细胞、因子及影响因素在AD中的作用及相关机制进行综述。     

阿尔茨海默病中Toll样受体与小胶质细胞的关系

阿尔茨海默病(Alzheimer’s disease,AD)是老年人常见的一种神经退行性疾病。目前AD的发病机制还不是很清楚,但大多数学者认为淀粉样蛋白沉积激活神经胶质细胞所导致的炎症反应是其核心病理机制,其中小胶质细胞是主要的炎症细胞。近期研究表明Toll样受体(Toll-like receptor,TLR)在小胶质细胞的激活过程中发挥着一定的作用。本文主要就近年来AD发病过程中TLR与小胶质细胞之间关系方面的研究进行综述。     

Aβ325～35诱导大鼠记忆减退与星形胶质细胞及NOS阳性细胞变化

目的　探讨Aβ2 5～ 3 5诱导模拟人类Alzheimer‘s病 (AD)的大鼠病理模型中星形胶质细胞变化与一氧化氮合酶神经元损伤引起的老年性记忆减退之间的关系。方法　双侧海马内注射 β-淀粉样多肽 2 5～ 3 5片段 (Aβ2 5～ 3 5 )制作大鼠AD模型 ,注射一周后采用NOS组化染色、GFAP免疫组化染色及NOS组化和GFAP双重染色分析大鼠海马GFAP与NOS的表达。结果　海马内注射Aβ2 5～ 3 5后出现海马星形胶质细胞增生、肥大、数目明显多于对照组 (P <0 0 5 ) ,并出现一氧化氮阳性星形胶质细胞 ;海马一氧化氮神经元数量较对照组显著减少 (P <0 0 5 )。结论　AD模型大鼠学习记忆功能低下与Aβ神经毒性导致NOS阳性神经元损伤、死亡直接相关 ,反应性星形胶质细胞参与Aβ导致NOS神经元细胞毒性损伤作用 ,间接导致学习记忆能力减退     

阿尔茨海默病的脑神经元凋亡机制

阿尔茨海默病（AD）是一种中枢神经系统退行性疾病,临床主要表现为认知功能障碍、行为异常及日常生活能力下降,主要神经病理改变有神经元变性、丢失引起的脑萎缩,细胞外的老年斑（senile plaque,SP）和细胞内的神经元纤维缠结（neurofibrillary tangle,NFT）.细胞凋亡与AD有密切的关系,β淀粉样蛋白（Aβ）在此过程中可能有重要的作用.近年来的研究还指出,细胞周期的异常可能是AD发生的较早期事件,这种异常的细胞周期也可导致细胞的凋亡,最终引发AD.该文介绍细胞周期异常和Aβ介导的细胞凋亡机制作一综述.     

Ccr2 deficiency impairs microglial accumulation and accelerates progression of Alzheimer-like disease

Microglia are the principal immune cells of the brain. In Alzheimer disease, these brain mononuclear phagocytes are recruited from the blood and accumulate in senile plaques. However, the role of microglia in Alzheimer disease has not been resolved. Microglia may be neuroprotective by phagocytosing amyloid-beta (Abeta), but their activation and the secretion of neurotoxins may also cause neurodegeneration. Ccr2 is a chemokine receptor expressed on microglia, which mediates the accumulation of mononuclear phagocytes at sites of inflammation. Here we show that Ccr2 deficiency accelerates early disease progression and markedly impairs microglial accumulation in a transgenic mouse model of Alzheimer disease (Tg2576). Alzheimer disease mice deficient in Ccr2 accumulated Abeta earlier and died prematurely, in a manner that correlated with Ccr2 gene dosage, indicating that absence of early microglial accumulation leads to decreased Abeta clearance and increased mortality. Thus, Ccr2-dependent microglial accumulation plays a protective role in the early stages of Alzheimer disease by promoting Abeta clearance.     

Identification of BACE1 cleavage sites in human voltage-gated sodium channel beta 2 subunit

Microglia cells are the brain counterpart of macrophages and function as the first defense in the brain. Although they are neuroprotective in the young brain, microglia cells may be primed to react abnormally to stimuli in the aged brain and to become neurotoxic and destructive during neurodegeneration. Aging-induced immune senescence occurs in the brain as age-associated microglia senescence, which renders microglia to function abnormally and may eventually promote neurodegeneration. Microglia senescence is manifested by both morphological changes and alterations in immunophenotypic expression and inflammatory profile. These changes are likely caused by microinvironmental factors, but intrinsic factors cannot yet be completely excluded. Microglia senescence appears to underlie the switching of microglia from neuroprotective in the young brain to neurotoxic in the aged brain. The hypothesis of microglia senescence during aging offers a novel perspective on their roles in aging-related neurodegeneration. In Parkinson's disease and Alzheimer's disease, over-activation of microglia may play an active role in the pathogenesis because microglia senescence primes them to be neurotoxic during the development of the diseases.     

Phagocytosis of Microglia in the Central Nervous System Diseases

Microglia, the resident macrophages of the central nervous system, rapidly activate in nearly all kinds of neurological diseases. These activated microglia become highly motile, secreting inflammatory cytokines, migrating to the lesion area, and phagocytosing cell debris or damaged neurons. During the past decades, the secretory property and chemotaxis of microglia have been well-studied, while relatively less attention has been paid to microglial phagocytosis. So far there is no obvious concordance with whether it is beneficial or detrimental in tissue repair. This review focuses on phagocytic phenotype of microglia in neurological diseases such as Alzheimer’s disease, multiple sclerosis, Parkinson’s disease, traumatic brain injury, ischemic and other brain diseases. Microglial morphological characteristics, involved receptors and signaling pathways, distribution variation along with time and space changes, and environmental factors that affecting phagocytic function in each disease are reviewed. Moreover, a comparison of contributions between macrophages from peripheral circulation and the resident microglia to these pathogenic processes will also be discussed.     

小胶质细胞的神经递质受体在阿尔茨海默病中的作用

阿尔茨海默病(Alzheimer’s disease,AD)是一种因蛋白错误折叠、聚积影响神经细胞功能,从而导致认知功能下降、行为异常的神经退行性疾病。小胶质细胞是中枢神经系统(central nervous system,CNS)中重要的免疫细胞之一,在AD病理过程中,根据其激活状态的不同小胶质细胞发挥神经保护或神经毒性作用。小胶质细胞上表达各类神经递质受体,这些受体参与介导小胶质细胞与神经细胞的双向沟通,在AD的病理进程中起到了不同的作用。该文重点介绍了小胶质细胞表面的γ-氨基丁酸(GABA)能、谷氨酸能、大麻素、胆碱能和肾上腺素能受体,以及它们与AD之间的关系,即小胶质细胞上的神经递质受体可以介导或影响小胶质细胞产生的神经保护或毒性作用,从而影响AD病理。阐明小胶质细胞上的神经递质受体在AD中的作用机制将会为探索合适的AD治疗靶点提供重要思路。     

Vimentin participates in microglia activation and neurotoxicity in cerebral ischemia

Microglia are the 'immune cells' of the brain and their activation plays a vital role in the pathogenesis of many neurodegenerative diseases. Activated microglia produce high levels of pro-inflammatory factors, such as TNFα, causing neurotoxicity. Here we show that vimentin played a key role in controlling microglia activation and neurotoxicity during cerebral ischemia. Deletion of vimentin expression significantly impaired microglia activation in response to LPS in vitro and transient focal cerebral ischemia in vivo. Reintroduction of the functional vimentin gene back into vimentin knockout microglia restored their response to LPS. More importantly, impairment of microglia activation significantly protected brain from cerebral ischemia-induced neurotoxicity. Collectively, we demonstrate a previously unknown function of vimentin in controlling microglia activation.     

RAGE与阿尔茨海默病关系的研究进展

阿尔茨海默病属于神经系统退行性疾病,该类疾病给社会和家庭带来了沉重的负担,且目前尚无一疗效突破性药物,已经成为一个严重的社会问题和经济问题。Aβ是阿尔茨海默病的重要发病机制之一,通过多种途径介导神经损伤,其中与细胞表面的结合位点结合而引发的病理损害成为当今的前沿认识。一方面,它们可以使Aβ聚集,造成细胞膜的直接损伤;另一方面,它们可以以受体的形式,参与细胞内的信号传导;另外,还可以激活细胞内吞作用,通过溶酶体途径造成细胞损伤。关于与Aβ结合的细胞表面结合位点,晚期糖基化终末产物受体备受瞩目。它是一种多功能受体,属于细胞表面免疫球蛋白家族成员,在神经元、小胶质细胞以及血管内皮细胞上都有表达,Aβ是它的配体之一。研究已证实,它与Aβ相互作用,通过激活细胞内不同的信号通路,对阿尔茨海默病的发生发展发挥重要作用。随着对它的不断深入研究,有望在防治退行性疾病方面产生新的治疗策略与措施。     

Catalpol protects dopaminergic neurons from LPS-induced neurotoxicity in mesencephalic neuron-glia cultures

Inflammation plays an important role in the pathogenesis of Parkinson's disease (PD). Microglia, the resident immune cells in the central nervous system, are pivotal in the inflammatory reaction. Activated microglia can induce expression of inducible nitric-oxide synthase (iNOS) and release significant amounts of nitric oxide (NO) and TNF-alpha, which can damage the dopaminergic neurons. Catalpol, an iridoid glycoside, contained richly in the roots of Rehmannia glutinosa, was found to be neuroprotective in gerbils subjected to transient global cerebral ischemia. But the effect of catalpol on inflammation-mediated neurodegeneration has not been examined. In this study, microglia in mesencephalic neuron-glia cultures were activated with lipopolysaccharide (LPS) and the aim of the study was to examine whether catalpol could protect dopaminergic neurons from LPS-induced neurotoxicity. The results showed that catalpol significantly reduced the release of reactive oxygen species (ROS), TNF-alpha and NO after LPS-induced microglial activation. Further, catalpol attenuated LPS-induced the expression of iNOS. As determined by immunocytochemical analysis, pretreatment by catalpol dose-dependently protected dopaminergic neurons against LPS-induced neurotoxicity. These results suggest that catalpol exerts its protective effect on dopaminergic neurons by inhibiting microglial activation and reducing the production of proinflammatory factors. Thus, catalpol may possess therapeutic potential against inflammation-related neurodegenerative diseases.     

The Distinct Role of ADAM17 in APP Proteolysis and Microglial Activation Related to Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disease with the symptom of cognitive impairment. The deposition of amyloid β (Aβ) peptide is believed to be the primary cause to neuronal dystrophy and eventually dementia. Aβ is the proteolytic product from its precursor amyloid precursor protein (APP) by β- and γ- secretase. An optional cleavage by α-secretase happens inside the Aβ domain. ADAM17 is supposed to be the regulated α-secretase of APP. Enhanced activity of ADAM17 leads to the increasing secretion of neuroprotective soluble APP α fragment and reduction of Aβ generation, which may be benefit to the disease. ADAM17 is then considered the potential therapeutic target for AD. Microglia activation and neuroinflammation is another important event in AD pathogenesis. Interestingly, ADAM17 also participates in the cleavage of many other membrane-bound proteins, especially some inflammatory factors related to microglia activation. The facilitating role of ADAM17 in inflammation and further neuronal damage has also been illustrated. In results, the activation of ADAM17 as the solution to AD may be a tricky task. The comprehensive consideration and evaluation has to be carried out carefully before the final treatment. In the present review, the distinct role of ADAM17 in AD-related APP shedding and neuroinflammatory microglial activation will be carefully discussed.     

小胶质细胞在帕金森病病理进展中的作用

帕金森病是中老年人常见的中枢神经系统退行性疾病,研究表明小胶质细胞的活化及其介导的神经炎症在帕金森病的病程进展中发挥重要作用,适度干预小胶质细胞的活化有望延缓帕金森病的进程。小胶质细胞是中枢神经系统固有的巨噬细胞,Notch信号途径可以调控小鼠外周巨噬细胞的分化及功能。Notch通路也参与调控小胶质细胞的激活、细胞因子的表达、吞噬活性的变化等,而这与活化的小胶质细胞介导的帕金森病等神经退行性疾病的病情进展相关。因此,本文将综述Notch信号途径与小胶质细胞介导的相关疾病的研究进展。