趋化因子参与阿尔茨海默病的研究进展

趋化因子在阿尔茨海默病(Alzheimer's disease,AD)的发病机制中发挥多重作用。AD是一种中枢神经系统的慢性炎症性疾病,其神经病理学特征包括神经原纤维缠结(neurofibrillary tangles,NFT)、β淀粉样蛋白(amyloid beta protein,Aβ)斑块、神经炎症和神经元突触丢失。趋化因子通过激活或调节炎症细胞和神经胶质细胞参与AD的病理机制,发挥了促炎和抗炎双重作用。AD患者血清、脑脊液和脑组织中的趋化因子水平发生相应的变化。该综述总结了趋化因子及其受体在AD中的生物活性以及变化规律,为临床治疗AD提供新的策略。     

G蛋白偶联受体/分泌酶复合体调节阿尔兹海默症发病进程的新机制

目的目前对于特异性调控分泌酶剪切淀粉样蛋白前体蛋白的分子机制尚不十分清楚,而临床上抗阿尔兹海默症(A lzhe im ers′D isease,AD)药物的疗效也不足以从根本上缓解病理症状的恶化。对G-蛋白偶联受体(G-prote in coup led receptors,GPCR s)在AD疾病进程的调节机制相关研究进展予以总结,对于以GPCR作为药物靶点的潜在可能性进行讨论。方法对于特异性调控分泌酶剪切淀粉样蛋白前体蛋白的分子机制相关的细胞生物学领域以及AD疾病模型上对于发病机制的研究进展进行总结归纳,并针对该领域的几个重要科学问题进行讨论。结果与结论GPCR对于AD疾病进程的调节机制,尤其是其与分泌酶形成的复合体对于β-淀粉样蛋白(amyloid-,βAβ)产生以及AD发病的调节机制,具有理想的特异性,可成为抗AD药物的新型潜在靶点。     

硫氧还蛋白的生物学及其与阿尔茨海默病和帕金森病的关系

硫氧还蛋白(thioredoxin，Trx)是一种具有氧化还原活性的小分子蛋白质，具有抗氧化、抗凋亡、调节转录因子活性等功能，在氧化还原调节和细胞信号转导中发挥重要作用。本文对哺乳动物的Trx及其与阿尔茨海默病(AD)和帕金森病(PD)的关系的研究进展进行综述。基于Trx的神经保护活性，增加Trx的表达可望成为AD和PD防治的新靶点。     

进入临床试验Ⅲ期以β淀粉样蛋白为靶标的抗阿尔采末病药物

阿尔采末病(AD)是一种常见的神经退行性疾病,目前尚无有效的治疗药物。随着AD发病机制研究的深入,β淀粉样蛋白(amyloid beta-peptide,Aβ)被认为是AD发病重要因素之一。因此,很多药物设计选择以Aβ为靶标,但这类药物的临床研究却受到不同程度的挫折,tramiprosate和semagacestat的临床试验已经提前终止。本文对目前进入临床试验Ⅲ期以Aβ为靶标的药物进行综述,以期为研究者提供参考。     

匹伐他汀对阿尔兹海默症作用机制的研究进展

阿尔兹海默症(AD)的主要病理学特征为β淀粉样蛋白(Aβ)沉积和tau蛋白过度磷酸化致神经纤维缠结,因此Aβ和tau是开发阿尔兹海默症药物的两大靶点。近些年的基础和临床研究,已证实他汀类药物对阿尔兹海默症有疗效。其中,匹伐他汀是他汀类新一代药,对AD的药理作用机制有:以Aβ为靶点的降胆固醇降脂作用、缓解氧化应激造成的细胞损伤作用、减少炎症反应作用、以及对神经血管和神经细胞及突触的保护作用,和以tau为靶点的减少tau蛋白总水平及其磷酸化水平,这些基础研究为相关临床研究提供了充分的依据。目前已有大量关于他汀类药物对AD疗效的临床报道,而对于匹伐他汀改善AD等神经疾病的相关研究还处于探索阶段,因此还未见具体匹伐他汀相关临床报道。     

酪氨酸磷酸化调节激酶1A在阿尔茨海默病中的作用和机制

阿尔茨海默病(Alzheimer’s disease, AD)是一种以学习记忆减退和认知功能障碍为特征的中枢神经系统退行性疾病,主要病理学改变为β-淀粉样蛋白(amyloid β-protein, Aβ)沉积和Tau蛋白异常磷酸化,但其病因及发病机制目前尚未完全阐明。双底物特异性酪氨酸磷酸化调节激酶1A(dual specificity tyrosine-phosphorylation-regulated kinase 1A,DYRK1A)是一种在进化中高度保守的蛋白激酶,与大脑发育异常、神经退行性改变、认知障碍和早发性AD相关。DYRK1A可通过磷酸化多种底物的丝氨酸或苏氨酸残基促进AD疾病中老年斑形成、神经纤维缠结、氧化应激和神经炎症反应,因此DYRK1A可能是防治AD的重要靶点。本文将对DYRK1A的结构、分布、功能及其在AD发病中的作用进行综述,旨在为AD的研究和治疗提供新的思路。     

阿托伐他汀对体外培养皮层神经元Rho-GTP酶家族的影响

阿托伐他汀 (atorvastatin, Ato) 属于他汀类调血脂类药物.许多研究表明他汀类药物可以降低AD的患病风险[1],但机制尚不完全清楚.另有很多证据显示他汀类药物有不依赖于其降脂作用的神经细胞保护作用[2-3].他汀类药物防治AD的机制除了与降低血清胆固醇有关外,可能还涉及其他许多机制:如他汀类药物可能通过减少细胞膜中胆固醇含量,从而改变淀粉样蛋白前体代谢途径,使β-淀粉样蛋白生成减少[4];他汀类药物可能通过抑制甲羟戊酸的合成,来抑制载脂蛋白E分泌,进而阻止老年斑块的形成[5];此外,他汀类药物具有神经保护作用可能与Rho/Rho激酶信号转导通路有关[6-7],如能明确该部分机制则至少可部分解释他汀类药物调脂作用以外的更广泛的药理活性.他汀类药物除抑制甲羟戊酸 (mevalonic acid, MVA) 合成,从而阻断角鲨烯生成胆固醇的体内过程外,还可抑制类异戊二烯如焦磷酸法尼基 (FPP) 和焦磷酸栊牛儿基栊牛儿基酯 (GGPP) 的生成.本实验拟从阿托伐他汀是否通过影响Rho-GTP蛋白的活性间接促进神经元树突发育的作用,为抗脑衰老及临床老年性痴呆的预防和治疗提供更多的分子生物学资料.     

阿尔茨海默病发病机制研究进展

阿尔茨海默病(AD)病因及发病机制尚未完全阐明,有关其发病机制有β-淀粉样蛋白级联假说、Tau蛋白假说、神经血管学说和氧化应激学说等多种.本文就现有较公认的发病机制研究进展作一综述.     

低分子多糖在阿尔茨海默病防治中的研究进展

β淀粉样蛋白(Aβ)级联学说揭示了Aβ在阿尔茨海默病(AD)的发病过程中起到了关键作用。越来越多的研究发现硫酸乙酰肝素蛋白聚糖及其糖链硫酸乙酰肝素(HS)能够与Aβ相结合并促进Aβ的产生与聚积,因此硫酸乙酰肝素蛋白聚糖和HS已成为研究AD防治方法的重要靶点。此文主要介绍了近年来低分子多糖尤其是HS类似物在AD防治中的研究进展。     

他汀类药物对于阿尔茨海默病的疗效

流行病学和药理学研究结果显示，胆固醇在阿尔茨海默病(Alzheimer’s disease．AD)的发生中起着重要作用，他汀类药物对于AD具有潜在的治疗作用，今后这类药物可能被用来治疗AD。本综述了目前他汀类药物对AD的研究报道，并对他汀类药物、胆固醇、AD之间的作用机制进行了探讨，为AD的治疗和他汀类药物的新应用提供参考。     

The potential pharmacological mechanisms of β-hydroxybutyrate for improving cognitive functions

β-Hydroxybutyl acid (βOHB), the most prevalent type of ketone in the human body, is involved in the pathogenesis of cognitive disorders, especially Alzheimer’s dementia (AD), through a variety of mechanisms, such as enhancing mitochondrial metabolism, regulating signaling molecule, increasing histone acetylation, affecting the metabolism of Aβ and Tau proteins, inhibiting inflammation and lipid metabolism, and regulating intestinal microbes. Based on the above findings, clinical drug development in AD has begun to focus on βOHB.     

Thyroid hormone prevents cognitive deficit in a mouse model of Alzheimer's disease

This study aimed to examine the feasibility of using thyroid hormone (TH) as a therapeutic agent for Alzheimer's disease (AD). Mice were injected intra-hippocampally aggregated amyloid β-peptide (Aβ) to produce AD animal model. Intraperitoneal administration of l-thyroxine (L-T4) into Aβ-induced AD model mice prevented their cognitive impairment and improved their memory function. The mechanisms of L-T4 treating AD might be associated with regulating cholinergic function, protecting the brains of AD model mice against damage from free radicals, and rescuing hippocampal neurons from apoptosis. The results of the present study indicate that the use of TH has some therapeutic potential in AD.     

Fucoidan, a sulfated polysaccharide from brown algae, improves cognitive impairment induced by infusion of Aβ peptide in rats

Fucoidan is a complex sulfated polysaccharide, derived from marine brown seaweed. In the present study, we investigated the effects of fucoidan on improving learning and memory impairment in rats induced by infusion of Aβ (1-40), and its possible mechanisms. The results indicated that fucoidan could ameliorate Aβ-induced learning and memory impairment in animal behavioral tests. Furthermore, fucoidan reversed the decreased activity of choline acetyl transferase (ChAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and content of acetylcholine (Ach), as well as the increased activity of acetylcholine esterase (AchE) and content of malondialdehyde (MDA) in hippocampal tissue of Aβ-injected rats. Moreover, these were accompanied by an increase of Bcl-2/Bax ratio and a decrease of caspase-3 activity. These results suggested that fucoidan could ameliorate the learning and memory abilities in Aβ-induced AD rats, and the mechanisms appeared to be due to regulating the cholinergic system, reducing oxidative stress and inhibiting the cell apoptosis.     

Metformin inhibits Aβ25‐35‐induced apoptotic cell death in SH‐SY5Y cells

Metformin, a first‐line drug for type‐2 diabetes, plays a potentially protective role in preventing Alzheimer's disease (AD), but its underlying mechanism is unclear. In this study, Aβ_25‐35‐treated SH‐SY5Y cells were used as a cell model of AD to investigate the neuroprotective effect of metformin, as well as its underlying mechanisms. We found that metformin decreased the cell apoptosis rate and death, ratio of Bcl‐2/Bax, and expression of NR2A and NR2B, and increased the expression of LC3 in Aβ_25‐35‐treated SH‐SY5Y cells. Metformin also reduced intracellular and extracellular Glu concentrations, as well as the intracellular concentration of Ca²⁺ and ROS in Aβ_25‐35‐treated SH‐SY5Y cells. These findings suggest that metformin inhibits Aβ_25‐35‐treated SH‐SY5Y cell death by inhibiting apoptosis, decreasing intracellular Ca²⁺ and ROS by reducing neurotoxicity of excitatory amino acids, and by possibly reversing autophagy disorder via regulating autophagy process.     

姜黄素通过抑制GSK-3β的活性防治AD的体外研究

目的探讨姜黄素(Curcumin)通过调节糖原合成激酶-3β(GSK-3β)的活性防治AD的机制。方法体外培养SHSY5Y细胞,转染pBACE1-mychis和pAPPswe,姜黄素处理细胞后,通过RT-PCR和Westernblot分别检测GSK-3β、β-链蛋白(β-catenin)和核内转录因子CyclinD1 mRNA水平和蛋白水平的表达情况,免疫荧光法检测GSK-3β和β-catenin的定位和阳性表达的变化,ELISA检测淀粉样蛋白(Aβ40/42)水平。结果Curcumin处理后,细胞内GSK-3β mRNA表达水平和蛋白水平都明显减弱;而GSK-3β的磷酸化形式GSK-3β-Ser9蛋白却明显增加,具有浓度-时间依赖性(P<0.05)。β-catenin和CyclinD1 mRNA表达水平和蛋白水平增加,呈浓度-时间依赖性(P<0.05)。免疫荧光染色结果不但证实了GSK-3β、β-catenin在细胞质内量的变化,而且还发现随着药物浓度的增加,β-catenin逐渐向细胞核内转移。Aβ40/42生成水平明显降低,呈浓度-时间依赖性(P<0.05)。结论GSK-3β是一个潜在性的AD治疗靶点,Curcumin能够通过抑制GSK-3β的活性来发挥防治AD的作用。     

Emerging amyloid beta (Ab) peptide modulators for the treatment of Alzheimer's disease (AD)

Background: According to the ‘amyloid cascade hypothesis’ of Alzheimer's disease (AD), abnormal processing of beta-amyloid precursor protein (βAPP) into toxic amyloid beta (Aβ)-peptides is central to the etiopathology of this uniquely human brain disorder. Objective: To review current AD drugs, pharmacological approaches and strategies aimed at modulating Aβ-peptide generation and/or aggregation in the treatment of AD. Methods: Data searches at various websites: Alzheimer Research Forum; individual drug company databases; Medline; Pharmaprojects database; unpublished research; inter-University research communications. Results/conclusion: Considerable research effort has focused on secretase-mediated mechanisms of βAPP processing, and the latest pharmacological strategies have used selective Aβ-peptide-lowering agents (SALA) to provide therapeutic benefit against Aβ-initiated neurodegenerative pathology. Currently, dedicated anticholinesterase, glutamatergic agonist and Aβ-peptide immunization have had little impact in the clinical treatment of AD. One unexpected benefit of statins (HMG-CoA inhibitors), besides their cholesterol lowering abilities, has been their ancillary effects in potentiating the enzymatic mechanisms that generate Aβ-peptides. The long-term benefits or complications of statin-based therapies for use in the clinical management of AD are not known.     

Potential beneficial effects of low molecular weight heparin on cognitive impairment in elderly patients on haemodialysis

Vascular cognitive impairment or mixed vascular cognitive impairment and Alzheimer's disease (AD) appear to be much more common in elderly patients than AD alone. Furthermore, vascular dementia (VaD) and AD are more prevalent in elderly patients receiving haemodialysis (HD), leading to a loss of independence and a poor quality of life. Hypotensive episodes in patients receiving HD contribute to vascular changes in the brain, with consequent progression of VaD and AD. The use of the lowest individually optimized bolus dose of low molecular weight heparin (LMWH) during HD, with fewer hypotensive episodes during and between HD procedures, may exert a sparing effect on changes in microvascular circulation and decrease the incidence of VaD and AD. We believe that long-term use of LMWH, with its direct effect on amyloid β protein (Aβ) in the blood and on Aβ accumulation in the brain and indirect effects on prevention of complement activation, may delay the progression of cognitive impairment in patients receiving HD. There is a need for a robustly designed, prospective trial to evaluate the effects of long-term treatment with LMWH on mild cognitive impairment, VaD and AD in elderly patients receiving maintenance HD.     

Progesterone exerts neuroprotective effects against Aβ-induced neuroinflammation by attenuating ER stress in astrocytes

The deposition of amyloid-β (Aβ) and neuroinflammation are critical pathological features of Alzheimer's disease (AD). Astrocytes are considered the principal immunoregulatory cells in the brain. Neurosteroid progesterone (PG) exerts neuromodulatory properties, particularly its potential therapeutic function in ameliorating AD. However, the role of PG and the neuroprotective mechanism involving in the regulation of neuroinflammation in astrocytes warrant further investigation. In this study, we found that Aβ significantly increased the processing of neuroinflammatory responses in astrocytes. The processing is induced by an increase activity of PERK/elF2ɑ-dependent endoplasmic reticulum (ER) stress. Additionally, the inhibition of ER stress activation by Salubrinal significantly suppressed the Aβ-induced neuroinflammatory responses in astrocytes. While the treatment of astrocytes with Aβ caused an increase of neuroinflammatory responses, PG significantly inhibited Aβ-induced neuroinflammatory cytokine production by suppressing ER stress activation together with attenuating PERK/elF2ɑ signalling. Taken together, these results indicate that PG exerts a neuroprotective effect against Aβ-induced neuroinflammatory responses, and significantly suppresses ER stress activation, which is an important mediator of the neurotoxic events occurring in Aβ-induced neuroinflammatory responses in astrocytes. These neuroprotective mechanisms may facilitate the development of therapies to ameliorate AD.     

Alzheimer disease therapeutics: Focus on the disease and not just plaques and tangles

The bulk of AD research during the last 25 years has been Aβ-centric based on a strong faith in the Amyloid Cascade Hypothesis which is not supported by the data on humans. To date, Aβ-based therapeutic clinical trials on sporadic cases of AD have been negative. Although most likely the major reason for the failure is that Aβ is not an effective therapeutic target for sporadic AD, initiation of the treatment at mild to moderate stages of the disease is blamed as too late to be effective. Clinical trials on presymptomatic familial AD cases have been initiated with the logic that Aβ is a trigger of the disease and hence initiation of the Aβ immunotherapies several years before any clinical symptoms would be effective. There is an urgent need to explore targets other than Aβ. There is now increasing interest in inhibiting tau pathology, which does have a far more compelling rationale than Aβ. AD is multifactorial and over 99% of the cases are the sporadic form of the disease. Understanding of the various etiopathogenic mechanisms of sporadic AD and generation of the disease-relevant animal models are required to develop rational therapeutic targets and therapies. Treatment of AD will require both inhibition of neurodegeneration and regeneration of the brain.     

Advances in the identification of γ-secretase inhibitors for the treatment of Alzheimer's disease

INTRODUCTION: In an attempt of altering the natural history of Alzheimer's disease (AD), several compounds have been developed with the aim of inhibiting γ-secretase, the enzymatic complex generating β-amyloid (Aβ) peptides (Aβ(1 - 40) and Aβ(1 - 42)), from amyloid precursor protein (APP). APP is believed to be involved in the pathophysiological cascade of AD. AREAS COVERED: This article briefly reviews the profile of γ-secretase inhibitors that have reached the clinic. The paper reviews studies from the primary English literature on γ-secretase inhibitors published before November 2011, searching through the PubMed database of NCBI by author and the following keywords: drugs targeting β-amyloid, γ-secretase inhibitors, dementia syndromes and Alzheimer's disease. EXPERT OPINION: Studies in both transgenic and non-transgenic animal models of AD have indicated that γ-secretase inhibitors, administered by the oral route, are able to lower brain Aβ concentrations. However, scanty data are available on the effects of these compounds on brain Aβ deposition after prolonged administration. γ-Secretase inhibitors may cause significant toxicity in experimental animals and in humans believed to be associated with the inhibition of the cleavage of Notch, a transmembrane receptor involved in regulating cell-fate decisions. Unfortunately, two large Phase III clinical trials of semagacestat in mild-to-moderate AD patients were prematurely interrupted because of the observation of a detrimental cognitive and functional effects of the drug, possibly due to its lack of selectivity on APP processing. New APP-selective γ-secretase inhibitors are being developed with the hope of overcoming the previous setbacks.