Immunotherapy for Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia worldwide. In AD the normal soluble amyloid β (sAβ) peptide is converted into oligomeric/fibrillar Aβ. The oligomeric forms of Aβ are thought to be the most toxic, while fibrillar Aβ becomes deposited as amyloid plaques and congophilic angiopathy, which serve as neuropathological markers of the disease. In addition the accumulation of abnormally phosphorylated tau as soluble toxic oligomers and as neurofibrillary tangles is a critical part of the pathology. Numerous therapeutic interventions are under investigation to prevent and treat AD. Among the more exciting and advanced of these approaches is vaccination. Active and passive Immunotherapy targeting only Aβ has been successful in many AD model animal trials; however, the more limited human data has shown much less benefit so far, with encephalitis occurring in a minority of patients treated with active immunization and vasogenic edema or amyloid-related imaging abnormalities (ARIA) being a complication in some passive immunization trials. Therapeutic intervention targeting only tau has been tested only in mouse models; and no approaches targeting both pathologies concurrently has been attempted, until very recently. The immune approaches tried so far were targeting a self-protein, albeit in an abnormal conformation; however, effective enhanced clearance of the disease associated conformer has to be balanced with the potential risk of stimulating excessive toxic inflammation. The design of future more effective immunomodulatory approaches will need to target all aspects of AD pathology, as well as specifically targeting pathological oligomeric conformers, without the use of any self-antigen.     

Apolipoprotein E and Alzheimer's disease

Genetic variation in apolipoprotein E (APOE) influences Alzheimer's disease (AD) risk. APOE ε4 alleles are the strongest genetic risk factor for late onset sporadic AD. The AD risk is dose dependent, as those carrying one APOE ε4 allele have a 2–3-fold increased risk, while those carrying two ε4 alleles have a 10–15-fold increased risk. Individuals carrying APOE ε2 alleles have lower AD risk and those carrying APOE ε3 alleles have neutral risk. APOE is a lipoprotein which functions in lipid transport, metabolism, and inflammatory modulation. Isoform specific effects of APOE within the brain include alterations to Aβ, tau, neuroinflammation, and metabolism. Here we review the association of APOE with AD, the APOE isoform specific effects within brain and periphery, and potential therapeutics.     

Novel lipid signaling pathways in Alzheimer's disease pathogenesis

Alzheimer's disease (AD) is the most common cause of dementia in the elderly. With an increasing longevity and the absence of a cure, AD has become not only a major health problem but also a heavy social and economic burden worldwide. In addition to the presence of abundant intra- and extra-cellular neurotoxic amyloid β (Aβ) peptides, which form the amyloid plaques, and intracellular hyperphosphorylated tau protein, the main component of neurofibrillary tangles, consistent evidence indicates that the AD brain is characterized by extensive neuroinflammatory processes. The 5-lipoxygenase (5LO) is a pro-inflammatory enzymatic pathway widely distributed within the central nervous system and is up-regulated in AD. In the last five years our group has been involved in unraveling the neurobiology of this protein and investigating its relationship with cellular and molecular events of functional importance in AD pathogenesis. By using a combination of in vitro and in vivo experimental tools and implementing genetic as well as pharmacological approaches today we know that 5LO is likely an endogenous regulator of Aβ formation via the modulation of the γ-secretase complex, and tau metabolism by modulating its phosphorylation state at specific epitopes via the cyclin-dependent kinase-5 (cdk-5). In addition, 5LO influences synaptic function and integrity and by doing so significantly affects learning and memory in the Tg2576 and 3xTg AD transgenic mouse models. Taken together our data establish this protein as a pleiotropic contributor to the development of the full spectrum of the AD-like phenotype in these mouse models of the disease, making it a viable therapeutic target for the treatment of AD in humans.     

The end of Alzheimer's disease—From biochemical pharmacology to ecopsychosociology: A personal perspective

The future of the Alzheimer's disease (AD) field involves a more complete understanding not only the state of current scientific approaches, but also the linguistic and cultural context of preclinical and clinical research and policy activities. The challenges surrounding dementia are large and growing but are only part of broader social and health concerns. In this latter context, the current state of research in the AD area is reviewed together with necessary priorities in moving forward. Creating a more optimistic future will depend less on genetic and reductionist approaches and more on environmental and intergenerative approaches that will aid in recalibrating the study of AD from an almost exclusive focus on biochemical, molecular and genetic aspects to better encompass “real world” ecological and psychosocial models of health.     

In vivo type 1 cannabinoid receptor availability in Alzheimer's disease

The endocannabinoid system (ECS) is an important modulatory and potentially neuroprotective homeostatic system in the brain. In Alzheimer's disease (AD), the role of type 1 cannabinoid receptor (CB₁R) is unclear, with contradictory findings in post-mortem studies showing upregulation, downregulation or unchanged CB₁R status. We have investigated CB₁R availability in vivo in patients with AD, in relation to amyloid deposition, cognitive functioning and apolipoprotein E (ApoE) genotype. Eleven AD patients and 7 healthy volunteers (HV) underwent combined [¹⁸F]MK-9470 PET and [¹¹C]PIB PET scans to assess CB₁R availability and amyloid deposition, respectively, and T1 volumetric MRI for partial volume correction. We found no difference in CB₁R availability between AD and HV, VOI-based fractional uptake values (FUR) were 0.043±0.01 for AD and 0.045±0.01 for controls (p=0.9). CB₁R availability did not correlate with neuropsychological test scores and was not modulated by ApoE genotype. As expected, global [¹¹C]PIB SUVR (standardized uptake value ratio) was increased in AD (SUVR 1.9±0.3) compared to HV (1.2±0.1) with p<0.001, but no correlation was found between amyloid β (Aβ) deposition and CB₁R availability. In conclusion, we found no in vivo evidence for a difference in CB₁R availability in AD compared to age-matched controls. Taken together with recently reported in vivo CB₁R changes in Parkinson's and Huntington's disease, these data suggest that the CB₁R is differentially involved in neurodegenerative disorders.     

New and emerging treatments for Alzheimer's disease

Introduction: Alzheimer's disease and other dementias represent a significant and increasing clinical challenge. Dementia is also associated with a substantial economic cost and burden to health service provision. Existing treatments slow the progression of symptoms of the disease, but their efficacy does not extend to all patients and is not sustained beyond an average of 6 months. It is, therefore, critical to address the current lack of effective treatments to target the underlying pathology and disease process in Alzheimer's disease.

Areas covered: This review aims to highlight the main areas of new therapeutic development and discuss some of the main therapies currently being evaluated in clinical trials. Despite a number of promising rationales for therapeutic treatments in Alzheimer's disease, very few of these avenues have been developed beyond preclinical studies. The predominant focus of the current article is on treatments currently in Phase II and Phase III clinical trials, but some other promising areas of development are also discussed. There are currently only three therapeutics being investigated in Phase III clinical trials. This emphasizes the substantial caution and underinvestment in treatment development in this area.

Expert opinion: There is a distinct lack of novel approaches in the pipeline, and whether there is a new disease-modifying therapy for Alzheimer's disease in the next 5 years almost entirely depends on the success of currently ongoing immunotherapy studies. Importantly, there is potential benefit in exploring existing licensed treatments alongside novel drug development to increase the focus on novel targets within this time frame.     

白藜芦醇治疗阿尔茨海默病的研究进展

神经退行性疾病是一种慢性进展性疾病,其特点是中枢神经系统神经元的逐渐丧失。由于血脑屏障的存在,经典的抗炎药物如类固醇激素和非甾体类抗炎药,对神经系统疾病的治疗作用有限。因此,开发新的抗炎药物,对于预防和治疗神经系统疾病具有重要的意义。白藜芦醇是一种有很强活性的天然多酚类物质,目前研究已显示其具有心血管保护、神经保护、免疫调节、肿瘤的化学预防作用。近年来还发现其具有抗神经炎症作用,可用于治疗神经精神性疾病,如帕金森病、阿尔茨海默病(AD)和亨廷顿症等。综述白藜芦醇对AD的保护作用及其机制研究进展,为进一步推进白藜芦醇用于防治AD的研究提供参考。     

Plasma inositol is not elevated in Alzheimer's disease

Brain inositol levels have been previously reported as elevated in Alzheimer's disease (AD) in brain. Brain inositol levels may be reflected in plasma levels. We therefore studied plasma inositol levels in 20 AD patients and 20 controls. Plasma inositol levels in the AD patients did not differ from values found in the controls. © 1998 John Wiley & Sons, Ltd.     

Therapeutic targets for Alzheimer's disease

Background: Alzheimer's disease (AD), the most common form of degenerative dementia, represents a tremendous unmet medical need. Although AD had already been described about 100 years ago and despite enormous research efforts, at present only few symptomatic treatment options exist for the more than 25 million patients worldwide. This situation might change as many targets for therapeutic intervention have been identified based on the in-depth study of the pathology of the disease in model systems and humans, and of its underlying genetics. Objective/methods: These targets are highlighted in the context of contemporary drug discovery for the identification of new therapies. Results/conclusions: ‘Translation’ of recent discoveries into disease-modifying therapies has not yet been accomplished. The future will show whether the current drug discovery and development ‘pipelines’ of pharmaceutical companies yield efficacious new medicines for AD.     

基于网络药理学研究当归芍药散防治阿尔茨海默病的作用机制

目的 探究当归芍药散防治阿尔茨海默病的作用机制。方法 选取当归芍药散中的当归、白芍、白术、川芎、茯苓、泽泻为研究对象,应用TCMSP数据库对6味中药主要化学成分进行筛选;使用TCMSP数据库,对筛选出的化合物及阿尔茨海默病进行靶点预测,选取当归芍药散与阿茨海默病一致的6个靶点蛋白作为后续研究对象,通过生物分子功能注释系统（MAS 3.0）及KEGG通路数据库进行通路注解及分析,得到当归芍药散治疗阿茨海默病的相关靶点通路预测图及相关信号通路。结果 从当归芍药散中筛选出35个化合物,可作用于阿尔茨海默病6个潜在的蛋白靶点,找出靶点的相关通路22条。作用通路涉及阿尔茨海默病发病机制相关的钙信号途径、炎症、免疫调节、细胞与细胞之间的信号交流、肌动蛋白细胞骨架的调节等各个环节,6味中药既有共同的成分及作用靶点、通路,又各有偏重,各通路间通过共有靶点连接,显示出不同成分间的多靶点、多途径的协同作用。结论 预测出当归芍药散治疗阿尔茨海默病可能与其调节炎症、免疫系统、钙信号、细胞与细胞之间的信号交流等机制有关。     

Effects of switching from an AChE inhibitor to a dual AChE-BuChE inhibitor in patients with Alzheimer's disease

ABSTRACT

Objective: Cholinesterase (ChE) inhibitors are the only medications approved for the treatment of Alzheimer's disease (AD). The features of ChE inhibitors differ considerably. In addition to acetylcholinesterase (AChE) inhibition, rivastigmine also inhibits butyrylcholinesterase (BuChE), providing dual AChE and BuChE inhibition. An observational study was performed to determine the response in routine clinical practice to switching AD patients to rivastigmine from a selective AChE inhibitor when that treatment no longer delivered a satisfactory clinical response.

Research design and methods: A prospective, multicentre, 3‐month observational trial in patients with mild to moderately severe AD (adjusted Mini Mental State Examination [MMSE] score 10–26) deteriorating (at least 2 adjusted MMSE points in last 6 months) on selective AChE inhibitor treatment. Adjusted MMSE, activities of daily living (ADL) and instrumental activities of daily living (IADL), the Zarit caregiver burden and global function (short Clinical Global Impression of Change, CGIC) scores were noted before the switch and 3 months after the switch.

Results: 225 patients entered the study. The switches made were from donepezil to rivastigmine (D‐R) in 188 patients, galantamine to rivastigmine (G‐R) in 33 patients and donepezil to galantamine (D‐G) in four patients. Ten patients discontinued due to adverse events and eight for other reasons. More than half of the switches were within 36 hours of a patient's first treatment visit. In the D‐R and G‐R groups, 67.7% and 66.7% of patients responded (CGIC score ≤ 4), respectively. In non-responders, worsening (CGIC score 5–7) was mild in approximately 80% or more of patients. Adjusted MMSE improved after the switch from both donepezil and galantamine to rivastigmine (+0.69 ± 3.2, p = 0.008 and +0.6 ± 1.6, p = 0.05, respectively). Mean ADL, IADL and Zarit scores remained stable. The proportion of patients on concomitant antipsychotic therapy diminished by 30.5% and benzodiazepines were discontinued in all patients, except one.

Conclusions: AD patients deteriorating on selective AChE inhibitor treatment can benefit from switching to a dual AChE-BuChE inhibitor, such as rivastigmine, in terms of stabilization of disease, improvement in cognitive function and reduction in the burden of concomitant psychoactive treatment. The switch was well tolerated. Confirmation of these results is required in a controlled study.     

槲皮素对阿尔茨海默病的作用机制研究新进展

阿尔茨海默病是老年人最常见的神经退行性疾病,由于世界人口老龄化的加快,阿尔茨海默病的发病率随之持续增长,中药或中药提取物对神经保护作用的研究不断增多.槲皮素是一种黄酮类化合物,能够保护神经元免受氧化损伤,减少脂质过氧化,抑制淀粉样蛋白的原丝形成.本文对槲皮素的来源、药代动力学、对阿尔茨海默病的作用机制的新进展进行了综述...     

Mitochondrial abnormalities: A primary basis for oxidative damage in Alzheimer's disease

The most striking feature of Alzheimer's disease (AD) is the number of abnormalities affecting essentially every aspect of brain homeostasis. Recent work suggests that increased oxidative stress that damages lipids, proteins, and nucleic acids and results in the accumulation of redox‐active metals may be responsible for the diversity of systems involved. Interestingly, all of the genetic factors, β‐protein precursor, presenilins, and apolipoprotein E, have been linked to reactive oxygen species production or apoptosis, a process intimately associated with oxidative stress. This leaves open the question of why oxidative damage is increased in AD. In studies of mitochondria, we demonstrated increased mitochondrial DNA specifically in vulnerable neurons in cases of AD, suggesting that AD is marked by a fundamental abnormality in neuronal metabolism. Oxidative stress, therefore, seems to be the element linking the multitude of changes in Alzheimer's disease to a fundamental metabolic deficiency. Drug Dev. Res. 46:26–33, 1999. © 1999 Wiley‐Liss, Inc.     

Reasons that prevent the inclusion of Alzheimer's disease patients in clinical trials

Aim

To assess reasons that prevent Alzheimer''s disease (AD) patients from being included in clinical trials.

Methods

In 2009, we reviewed the Lille Memory Clinic''s case database to identify patients suitable for inclusion in four AD clinical trials. An initial selection was made on the basis of four criteria: (i) a diagnosis of AD (with or without white matter lesions [WML]), (ii) age, (iii) mini mental state examination (MMSE) score and (iv) symptomatic treatment of AD (cholinesterase inhibitors/memantine). Next, data on patients fulfilling these criteria were reviewed against all the inclusion/exclusion criteria for four clinical trials performed in 2009 at the Memory Clinic. Reasons for non-inclusion were analyzed.

Results

Two hundred and five patients were selected according to the four initial criteria. Reasons for subsequently not including some of patients in clinical trials were abnormalities on MRI (56.9%, 88.9% of which were WML), unauthorized medication (37.3%), the lack of a study partner/informant (37.1%), the presence of a non-authorized disease (24.4%), contraindication to MRI (9%), a change in diagnosis over time (3.9%), visual/auditory impairments (2.9%), alcohol abuse (2%) and an insufficient educational level (1%).

Conclusion

A high proportion of AD patients presented with vascular abnormalities on MRI. This was not unexpected, since the patients were selected from the database and, as shown in epidemiologic studies, cerebrovascular diseases are frequently associated with AD. The presence of a study partner is essential for enabling a patient to participate in clinical trials because of the need to record reliably primary and secondary outcomes.     

Impact of donepezil treatment for Alzheimer's disease on caregiver time

SUMMARY

Objective: To assess the impact of donepezil treatment compared with placebo on caregiver time spent assisting patients with Alzheimer's disease (AD).

Research design and methods: Patient and caregiver data were collected as part of a 1-year, prospective, double-blind, randomized, placebo-controlled trial. The Resource Utilization in Dementia (RUD) questionnaire was used to record caregiver time at study baseline and at Weeks 12, 24, 36, and 52. This analysis focuses solely on those caregivers who were actively (> 0?h/day reported on the RUD) providing care at study baseline.

Main outcome measures: The change in time relative to baseline that caregivers spent assisting patients over the course of the study.

Results: The active caregiver population was composed of 96 caregivers of donepezil-treated patients and 94 caregivers of patients receiving placebo. Over the course of the 1-year study, and as the condition of the AD patients deteriorated, it was expected that caregiver time would increase. As expected, after 52?weeks, caregivers of placebo patients were providing almost 2?h each day (106.8?min) more care than they had done at study baseline. For those caregivers of donepezil-treated patients, although they were spending more time caring than they had done at study baseline, their time burden had only increased by 42.6?min more each day. This difference in caring time between the 2 groups, relative to baseline at Week 52, was 1.1?h (64.2?min) each day, and was significant (?p = 0.03).

Conclusion: Caregiver time devoted to helping an AD patient typically increases with the severity of the disease. By helping the patient maintain his/her ability to perform activities of daily living for longer, treatment with donepezil is not only beneficial to the patient, but also has positive time-burden implications for the caregiver.     

Muscarinic and nicotinic acetylcholine receptor agonists: current scenario in Alzheimer's disease therapy

Objectives

Alzheimer's disease (AD ) has become the primary cause of dementia. It shows a progressive cognitive dysfunction with degenerating neurons. Acetylcholine receptors (AC hRs) propagate the cognitive ability and it consists of two primary members namely muscarinic (mAChR s) and nicotinic receptors (nAChR s). Where mAChR s is G‐protein coupled receptor, (nAChR s) are ligand‐gated ion channels. The conventional therapeutic regimen for AD consists of three acetylcholinestearse inhibitors while a single NMDA receptor antagonist. Researchers around the globe are developing new and modifying the existing AC hRs agonists to develop lead candidates with lower risk to benefit ratio where benefits clearly outweigh the adverse events.

Key findings

We have searched PubMed, MEDLINE , Google scholar, Science Direct and, Web of Science with keywords “Muscarinic/Nicotinic acetylcholine receptor, agonists and, AD ”. The literature search included articles written in English. Scientific relevance for clinical studies, basic science studies is eligibility criteria for articles referred in this paper. M1 is the primary muscarinic subtype while α7 is the primary nAChR subtype that is responsible for cognition and memory and these two have been the major recent experimental targets for mAChR agonist strategy.

Summary

The last cholinergic receptor agonist to enter phase 3 trial was EVP ‐6124 (Enceniclin) but was withdrawn due to severe gastrointestinal adverse effects. We aim to present an overview of the efforts and achievements in targeting Muscarinic and Nicotinic acetylcholine receptor in the current review for development of better AD therapeutics.