Cholinesterase inhibition: is there evidence for disease-modifying effects?

Impacts of oxidants and antioxidants on the emergence and progression of Alzheimer's disease

The brain shows a high sensitivity to oxidative stress (OS). Thus, the maintenance of homeostasis of the brain regarding the reduction-oxidation (redox) situation is crucial for the regular function of the central nervous systems (CNS). The imbalance between the reactive oxygen species (ROS) and the cellular mechanism might lead to the emergence of OS, causing profound cell death as well as tissue damages and initiating neurodegenerative disorders (NDDs). Characterized by the cytoplasmic growth of neurofibrillary tangles and extracellular β-amyloid plaques, Alzheimer's disease (AD) is a complex NDD that causes dementia in adult life with severe manifestations. Nuclear factor erythroid 2-related factor 2 (NRF2) is a key transcription factor that regulates the functional expression of OS-related genes and the functionality of endogenous antioxidants. In the case of oxidative damage, NRF2 is transferred to the nucleus and attached to the antioxidant response element (ARE) that enhances the sequence to initiate transcription of the cell-protecting genes. This review articulates various mechanisms engaged with the generation of active and reactive species of endogenous and exogenous oxidants and focuses on the antioxidants as a body defense system regarding the NRF2-ARE signaling path in the CNS.

A mechanistic survey of Alzheimer's disease

Alzheimer's disease (AD) is the most common, age-dependent neurodegenerative disorder. While AD has been intensively studied from different aspects, there is no effective cure for AD, largely due to a lack of a clear mechanistic understanding of AD. In this mini-review, we mainly focus on the discussion and summary of mechanistic causes of Alzheimer's disease (AD). While different AD mechanisms illustrate different molecular and cellular pathways in AD pathogenesis, they do not necessarily exclude each other. Instead, some of them could work together to initiate, trigger, and promote the onset and development of AD. In a broader viewpoint, some AD mechanisms (e.g., amyloid aggregation mechanism, microbial infection/neuroinflammation mechanism, and amyloid cross-seeding mechanism) could also be applicable to other amyloid diseases including type II diabetes, Parkinson's disease, and prion disease. Such common mechanisms for AD and other amyloid diseases explain not only the pathogenesis of individual amyloid diseases, but also the spreading of pathologies between these diseases, which will inspire new strategies for therapeutic intervention and prevention for AD.

Cholinesterase Inhibitory Potential of Quercetin towards Alzheimer's Disease - A Promising Natural Molecule or Fashion of the Day? - A Narrowed Review

Natural substances are known to have strong protective effects against neurodegenerative diseases. Among them, phenolic compounds, especially flavonoids, come to the fore with their neuroprotective effects. Since quercetin, which is found in many medicinal plants and foods, is also taken through diet, its physiological effects on humans are imperative. Many studies have been published up to date on the neuroprotective properties of quercetin, a flavanol derivative. However, there is no review published so far summarizing the effect of quercetin on the cholinesterase (ChE) enzymes related to the cholinergic hypothesis, which is one of the pathological mechanisms of Alzheimer's Disease (AD). However, ChE inhibitors, regardless of natural or synthetic, play a vital role in the treatment of AD. Although the number of studies on the ChE inhibitory effect of quercetin is limited, it deserves to be discussed in a review article. With this sensitivity, the neuroprotective effect of quercetin against AD through ChE inhibition was scrutinized in the current review study. In addition, studies on the bioavailability of quercetin and its capacity to cross the blood-brain barrier and how this capacity and bioavailability can be increased were given. Generally, studies containing data published in recent years were obtained from search engines such as PubMed, Scopus, and Medline and included herein. Consequently, quercetin should not be considered as a fashionable natural compound and should be identified as a promising compound, especially with increased bioavailability, for the treatment of AD.

An update on the utility and safety of cholinesterase inhibitors for the treatment of Alzheimer's disease

Introduction: Alzheimer's disease (AD) is the most common cause of major neurocognitive disorders with a prevalence in the US of about 5.7 million in 2018. With the disease burden projected to increase dramatically in the coming years, it is imperative to review the current available treatment regimens for their safety and utility. The cholinesterase inhibitors (ChEIs) have continued to play a pivotal role in managing the symptoms and possibly slowing the rate of progression of AD since 1993. Owing to their being a mainstay in the treatment of AD, the safety and efficacy of prescribing these drugs needs to be reviewed often, especially with the approval of new formulations and doses.Areas covered: The three ChEIs currently approved by the FDA are donepezil, rivastigmine and galantamine. This article will review the safety and tolerability of these ChEIs and analyze the potential disease modifying properties of these drugs. The authors have reviewed all recent literature including review articles, meta-analyzes, clinical trials and more.Expert opinion: These ChEIs differ subtly in their mechanisms of action, in their tolerability and safety and FDA-approved indications. All are considered first-line, symptomatic treatments of the various phases of AD and may even have potentially disease-modifying effects.

Design, synthesis, characterization of peripherally tetra-pyridine-triazole-substituted phthalocyanines and their inhibitory effects on cholinesterases (AChE/BChE) and carbonic anhydrases (hCA I, II and IX)

In this study, phthalocyanine precursors (5and9) and 1,2,3-triazole-substituted metal-free and metallo phthalocyanines (9a–c) were designed and synthesized for the first time and evaluatedin vitrofor key molecular targets.

Recent Progress in the Pharmacotherapy of Alzheimer's Disease

Alzheimer's disease is the most common major neurocognitive disorder with substantial social and economic impacts. This article is an update on current pharmacotherapy, advancements in biomarker use, and drugs in the pipeline for this disease. To date, no new drug has qualified to be added to the current therapeutic arsenal comprising cholinesterase inhibitors and the NMDA receptor antagonist memantine. Drugs in the pipeline include symptomatic therapies that are neurotransmitter-based, but mostly disease-modifying therapies. The latter have yielded disappointing results by focusing mainly on the two pathophysiological hallmarks of Alzheimer's disease: Aβ amyloid deposits and tau protein aggregates forming neurofibrillary tangles. These unsuccessful trials may have resulted from studying these drugs 'too late' relative to Alzheimer's disease onset, in addition to focusing only on the amyloid cascade. In fact, Alzheimer's disease is a complex multifactorial disease. Combining different biomarkers might enhance our ability to identify those patients most at risk of developing the disease, and better predict their conversion rates. Furthermore, adopting an integrative treatment approach by targeting additional pathophysiological pathways in Alzheimer's disease such as inflammation and oxidative stress could be the key to better outcomes in Alzheimer's disease pharmacotherapy research.

Coumarin derivatives bearing benzoheterocycle moiety: synthesis, cholinesterase inhibitory, and docking simulation study

Objective(s):

To investigate the efficiency of a novel series of coumarin derivatives bearing benzoheterocycle moiety as novel cholinesterase inhibitors.

Materials and Methods:

Different 7-hydroxycoumarin derivatives were synthesized via Pechmann or Knoevenagel condensation and conjugated to different benzoheterocycle (8-hydroxyquinoline, 2-mercaptobenzoxazole or 2-mercaptobenzimidazole) using dibromoalkanes 3a-m: Final compounds were evaluated against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) by Ellman’s method. Kinetic study of AChE inhibition and ligand-protein docking simulation were also carried out for the most potent compound 3b.

Results:

Some of the compounds revealed potent and selective activity against AChE. Compound 3b containing the quinoline group showed the best activity with an IC₅₀ value of 8.80 μM against AChE. Kinetic study of AChE inhibition revealed the mixed-type inhibition of the enzyme by compound 3b. Ligand-protein docking simulation also showed that the flexibility of the hydrophobic five carbons linker allows the quinoline ring to form π-π interaction with Trp279 in the PAS.

Conclusion:

We suggest these synthesized compounds could become potential leads for AChE inhibition and prevention of AD symptoms.

New tacrine-derived AChE/BuChE inhibitors: Synthesis and biological evaluation of 5-amino-2-phenyl-4H-pyrano[2,3-b]quinoline-3-carboxylates

A series of poly-functionalized tacrine-derived compounds namely 5-amino-2-phenyl-4H-pyrano[2,3-b]quinoline-3-carboxylates were designed and synthesized as cholinesterases inhibitors. The in vitro inhibition assay against AChE and BuChE demonstrated that most of compounds had potent AChE inhibitory with reserving potential of BuChE inhibition. Among them, compound 6i bearing a 4-(3-bromophenyl) moiety showed the most potent activity against AChE/BuChE (IC₅₀s values of 0.069 and 1.35 μM, respectively). The anti-AChE activity of 6i was five times more than that of tacrine. The SAR study revealed that chloro/bromo substituent at ortho or meta position of the 4-phenyl ring can improve the anticholinesterase activity.

DL0410, a novel dual cholinesterase inhibitor, protects mouse brains against Aβ-induced neuronal damage via the Akt/JNK signaling pathway

AIM

1,1'-([1,1'-Biphenyl]-4,4'-diyl)bis(3-(piperidin-1-yl)propan-1-one)dihydrochloride (DL0410) is a novel synthetic dual acetylcholinesterase (AChE)/butyrocholinesterase (BuChE) inhibitor, which has shown a potential therapeutic effect on Alzheimer's disease (AD). In this study we examined whether DL0410 produced neuroprotective effects in an AD cellular model and an Aβ1-42-induced amnesia mouse model.

METHODS

The in vitro inhibitory activities against AChE and BuChE were estimated using Ellman's assay. Copper-induced toxicity in APPsw-SY5Y cells was used as AD cellular model, the cell viability was assessed using MTS assay, and cell apoptosis was evaluated based on mitochondrial membrane potential detection. Aβ1-42-induced amnesia mouse model was made in male mice by injecting aggregated Aβ1-42 (2 μg in 2 μL 0.1% DMSO) into the right cerebral ventricle. Before and after Aβ1-42 injection, the mice were orally administered DL0410 (1, 3, 9 mg·kg-1·d-1) or rivastigmine (2 mg·kg-1·d-1) for 3 and 11 d, respectively. Memory impairments were examined using Morris water maze (MWM) test and passive avoidance test. The expression levels of APP, CREB, BDNF, JNK and Akt in the mouse brains were measured with either immunohistochemistry or Western blotting.

RESULTS

DL0410 exhibited in vitro inhibitory abilities against AChE and BuChE with IC50 values of 0.286±0.004 and 3.962±0.099 μmol/L, respectively, which were comparable to those of donepezil and rivastigmine. In APPsw-SY5Y cells, pretreatment with DL0410 (1, 3, and 10 μmol/L) decreased the phosphorylation of JNK and increased the phosphorylation of Akt, markedly decreased copper-stimulated Aβ1-42 production, reversed the loss of mitochondrial membrane potential, and dose-dependently increased the cell viability. In Aβ1-42-treated mice, DL0410 administration significantly ameliorated learning and memory deficits in MWM test and passive avoidance test. Furthermore, DL0410 administration markedly decreased Aβ1-40/42 deposits in mouse cerebral cortices, and significantly up-regulated neurotrophic CREB/BDNF. Meanwhile, Akt/JNK signaling pathway may play a key role in the neuroprotective effect of DL0410.

CONCLUSION

DL0410 ameliorates cognitive deficit and exerts neuronal protection in AD models, implicating this compound as a candidate drug for the prevention and therapy of AD.

Antioxidative Properties and Effect of Quercetin and Its Glycosylated Form (Rutin) on Acetylcholinesterase and Butyrylcholinesterase Activities

This study sought to investigate the anticholinesterase and antioxidative properties of quercetin and its glycosylated conjugate, rutin. The in vitro inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities, inhibition of Fe2+-induced lipid peroxidation in rat’s brain homogenates, radicals scavenging, and Fe2+-chelating abilities of the flavonoids were investigated in vitro with concentrations of the samples ranging from 0.06 to 0.6 mM. Quercetin had significantly higher AChE and BChE inhibitory abilities than rutin. Quercetin also had stronger inhibition of Fe2+-induced lipid peroxidation in rat’s brain homogenates. Similarly, quercetin had higher radical scavenging abilities than rutin. Quercetin also had stronger Fe2+-chelating ability than rutin. The inhibition of cholinesterases and antioxidative properties are possible mechanisms by which the flavonoids can be used in the management of oxidative stress–induced neurodegeneration.

(-)-Meptazinol-melatonin hybrids as novel dual inhibitors of cholinesterases and amyloid-β aggregation with high antioxidant potency for Alzheimer's therapy

The multifactorial pathogenesis of Alzheimer's disease (AD) implicates that multi-target-directed ligands (MTDLs) intervention may represent a promising therapy for AD. Amyloid-β (Aβ) aggregation and oxidative stress, two prominent neuropathological hallmarks in patients, play crucial roles in the neurotoxic cascade of this disease. In the present study, a series of novel (-)-meptazinol-melatonin hybrids were designed, synthesized and biologically characterized as potential MTDLs against AD. Among them, hybrids 7-7c displayed higher dual inhibitory potency toward cholinesterases (ChEs) and better oxygen radical absorbance capacity (ORAC) than the parental drugs. Furthermore, compound 7c could effectively inhibit Aβ self-aggregation, showed favorable safety and the blood-brain barrier (BBB) permeability. Therefore, 7c may serve as a valuable candidate that is worthy of further investigations in the treatment of AD.

Multi-target tacrine-coumarin hybrids: cholinesterase and monoamine oxidase B inhibition properties against Alzheimer's disease

A series of novel tacrine-coumarin hybrids were designed, synthesized and evaluated as multi-target agents against Alzheimer's disease. The biological assays indicated that most of compounds displayed potent inhibitory activity toward AChE and BuChE, and clearly selective inhibition for MAO-B. Among these compounds, 14c exhibited strong inhibitory activity for AChE (IC50 values of 33.63 nM for eeAChE and 16.11 nM for hAChE) and BuChE (IC50 values of 80.72 nM for eqBuChE and 112.72 nM for hBuChE), and the highest inhibitory activity against hMAO-B (IC50 value of 0.24 μM). Kinetic and molecular modeling studies revealed that 14c was a mixed-type inhibitor, binding simultaneously to catalytic, peripheral and mid-gorge sites of AChE. It was also a competitive inhibitor, which covered the substrate and entrance cavities of MAO-B. Moreover, 14c could penetrate the CNS and show low cell toxicity. Overall, these results suggested that 14c might be an excellent multi-target agent for AD treatment.

Selective acetyl- and butyrylcholinesterase inhibitors reduce amyloid-β ex vivo activation of peripheral chemo-cytokines from Alzheimer's disease subjects: exploring the cholinergic anti-inflammatory pathway

Increasing evidence suggests that elevated production and/or reduced clearance of amyloid-β peptide (Aβ) drives the early pathogenesis of Alzheimer's disease (AD). Aβ soluble oligomers trigger a neurotoxic cascade that leads to neuronal dysfunction, neurodegeneration and, ultimately, clinical dementia. Inflammation, both within brain and systemically, together with a deficiency in the neurotransmitter acetylcholine (ACh) that underpinned the development of anticholinesterases for AD symptomatic treatment, are invariable hallmarks of the disease. The inter-relation between Aβ, inflammation and cholinergic signaling is complex, with each feeding back onto the others to drive disease progression. To elucidate these interactions plasma samples and peripheral blood mononuclear cells (PBMCs) were evaluated from healthy controls (HC) and AD patients. Plasma levels of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and Aβ were significantly elevated in AD vs. HC subjects, and ACh showed a trend towards reduced levels. Aβ challenge of PBMCs induced a greater release of inflammatory cytokines interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-α) from AD vs. HC subjects, with IL-10 being similarly affected. THP-1 monocytic cells, a cell culture counterpart of PBMCs and brain microglial cells, responded similarly to Aβ as well as to phytohaemagglutinin (PHA) challenge, to allow preliminary analysis of the cellular and molecular pathways underpinning Aβ-induced changes in cytokine expression. As amyloid-β precursor protein expression, and hence Aβ, has been reported regulated by particular cytokines and anticholinesterases, the latter were evaluated on Aβ- and PHA-induced chemocytokine expression. Co-incubation with selective AChE/BuChE inhibitors, (-)-phenserine (AChE) and (-)-cymserine analogues (BuChE), mitigated the rise in cytokine levels and suggest that augmentation of the cholinergic anti-inflammatory pathway may prove valuable in AD.

Long-term efficacy and toxicity of cholinesterase inhibitors in the treatment of Alzheimer disease

Though the symptoms of Alzheimer disease go on for years, the phase 3 trials of the cholinesterase inhibitors (ChEIs), the current mainstay of symptomatic pharmacotherapy for this condition, were typically of only 3- to 6-months' duration. We have limited data on long-term (that is, a year or more) therapy with these agents. In this review, we explore the available information on the biological and clinical effects of long-term ChEI therapy, what happens when these agents are discontinued, and examine what others have recommended An individualized approach to deciding on whether to carry on with a ChEI should be taken. If continued, treatment goals should be clarified and patients monitored over time, for both drug-related benefits and adverse effects.

Protective effect of a sesamin derivative, 3-bis (3-methoxybenzyl) butane-1, 4-diol on Aβ-stressed PC12 cells

Amyloid beta-protein (Aβ) is involved in the pathogenesis of Alzheimer's disease (AD). Aβ induces free radical production in neuronal cells, leading to oxidative stress and up-regulation of c-Jun N-terminal kinases (JNK), extracellular-signal-regulated kinases (ERK), p38 mitogen-activated protein kinase (MAPK) pathways and pro-apoptotic Bax expression. Sesamin has been shown to have protection to several models of neurodegenerative diseases by its antioxidant and anti-inflammatory properties. In the present study, we examined the neuroprotective effect of a sesamin derivative, 3-bis (3-methoxybenzyl) butane-1,4-diol (BBD) on Aβ1-42 induced cytotoxicity of PC12 cells. Aβ1-42 induced lipid peroxidation, calcium, reactive oxygen species from the PC12 cells. The effect of BBD on these harmful factors and the related signaling pathways were examined by biochemical and western blot assays. The result showed that BBD protected PC12 cells from Aβ1-42 induced cytotoxicity with the increased cell viability and acetylcholine release, and the decreased lactate dehydrogenase, malondialdehyde and calcium release. BBD significantly reduced Aβ-induced JNK, ERK, p38 MAPK pathways and Bax expression in PC12 cells. Therefore the neuroprotective effect of BBD on Aβ-induced cytotoxicity was involved with antioxidant and anti-inflammatory effects. The result would help the development of new CNS drug for protection of AD.

Effect of cholinergic signaling on neuronal cell bioenergetics

Alzheimer's disease (AD) patients have reduced brain acetylcholine and reversing this deficit yields clinical benefits. In this study we explored how increased cholinergic tone impacts cell bioenergetics, which are also perturbed in AD. We treated SH-SY5Y neuroblastoma cells with carbachol, a cholinergic agonist, and tested for bioenergetic flux and bioenergetic infrastructure changes. Carbachol rapidly increased both oxidative phosphorylation and glycolysis fluxes. ATP levels rose slightly, as did cell energy demand, and AMPK phosphorylation occurred. At least some of these effects depended on muscarinic receptor activation, ER calcium release, and ER calcium re-uptake. Our data show that increasing cholinergic signaling enhances cell bioenergetics, and reveal mechanisms that mediate this effect. Phenomena we observed could potentially explain why cholinesterase inhibitor therapy increases AD brain glucose utilization and N-acetyl aspartate levels. The question of whether cholinesterase inhibitors have a disease modifying effect in AD has long been debated; our data suggest a theoretical mechanism through which such an effect could potentially arise.

3-[3-(3-florophenyl-2-propyn-1-ylthio)-1, 2, 5-thiadiazol-4-yl]-1, 2, 5, 6-tetrahydro-1- methylpyridine oxalate, a novel xanomeline derivative, improves neural cells proliferation and survival in adult mice

The present study analyzed the influence of 3-[3-(3-florophenyl-2-propyn-1-ylthio)-1, 2, 5-thiadiazol-4-yl]-1, 2, 5, 6-tetrahydro-1-methylpyridine oxalate (EUK1001), a novel xanomeline derivative of the M₁/M₄ receptor agonist, on hippocampal neurogenesis in adult C57BL6 mice. Results showed that 15-day EUK1001 treatment via intraperitoneal injection promoted neural cell proliferation in the dentate gyrus, although cell differentiation did not change. The majority of bromodeoxyuridine-positive cells co-expressed the immature neuronal marker doublecortin. In addition, the level of neurogenesis in the subventricular zone was not altered. Brain-derived neurotrophic factor mRNA expression was up-regulated following EUK1001 treatment, but no change was observed in expression of camp-responsive element binding protein 1, paired box gene 6, vascular endothelial growth factor alpha, neurogenic differentiation factor 1, and wingless-related mouse mammary tumor virus integration site 3A mRNA. These experimental findings indicated that EUK1001 enhanced proliferation and survival of hippocampal cells, possibly by increasing brain-derived neurotrophic factor expression.

Recent advances in the multitarget-directed ligands approach for the treatment of Alzheimer's disease

With 27 million cases worldwide documented in 2006, Alzheimer's disease (AD) constitutes an overwhelming health, social, economic, and political problem to nations. Unless a new medicine capable to delay disease progression is found, the number of cases will reach 107 million in 2050. So far, the therapeutic paradigm one-compound-one-target has failed. This could be due to the multiple pathogenic mechanisms involved in AD including amyloid β (Aβ) aggregation to form plaques, τ hyperphosphorylation to disrupt microtubule to form neurofibrillary tangles, calcium imbalance, enhanced oxidative stress, impaired mitochondrial function, apoptotic neuronal death, and deterioration of synaptic transmission, particularly at cholinergic neurons. Approximately 100 compounds are presently been investigated directed to single targets, namely inhibitors of β and γ secretase, vaccines or antibodies that clear Aβ, metal chelators to inhibit Aβ aggregation, blockers of glycogen synthase kinase 3β, enhancers of mitochondrial function, antioxidants, modulators of calcium-permeable channels such as voltage-dependent calcium channels, N-methyl-D-aspartate receptors for glutamate, or enhancers of cholinergic neurotransmission such as inhibitors of acetylcholinesterase or butyrylcholinesterase. In view of this complex pathogenic mechanisms, and the successful treatment of chronic diseases such as HIV or cancer, with multiple drugs having complementary mechanisms of action, the concern is growing that AD could better be treated with a single compound targeting two or more of the pathogenic mechanisms leading to neuronal death. This review summarizes the current therapeutic strategies based on the paradigm one-compound-various targets to treat AD. A treatment that delays disease onset and/or progression by 5 years could halve the number of people requiring institutionalization and/or dying from AD. 

Abhorring the vacuum: use of Alzheimer’s disease medications in frontotemporal dementia

There is no dedicated therapy for frontotemporal dementia (FTD). In order to treat the often devastating behavioral disturbances that interfere with both normal social functioning and the ability of caregivers to provide needed support, off-label medication usage is frequent. In addition to antidepressant and antipsychotic medications, which afford some benefits, US FDA-approved treatments for Alzheimer's disease are often used, including both cholinesterase inhibitors and memantine. Here, we review the various clinical manifestations of FTD, a general approach to treatment and the goals of any potential therapies. We review all of the existing literature on the use of cholinesterase inhibitors and memantine in FTD. While cholinesterase inhibitors do not currently have a place in FTD treatment, memantine may be helpful, although the results of two placebo-controlled trials with this agent are not yet available. Finally, we discuss our view that such approaches will probably become supplanted by rational, molecularly-based therapies currently in development.

Glycogen synthase kinase 3 inhibitors in the next horizon for Alzheimer's disease treatment

Glycogen synthase kinase 3 (GSK-3), a proline/serine protein kinase ubiquitously expressed and involved in many cellular signaling pathways, plays a key role in the pathogenesis of Alzheimer's disease (AD) being probably the link between β-amyloid and tau pathology. A great effort has recently been done in the discovery and development of different new molecules, of synthetic and natural origin, able to inhibit this enzyme, and several kinetics mechanisms of binding have been described. The small molecule called tideglusib belonging to the thiadiazolidindione family is currently on phase IIb clinical trials for AD. The potential risks and benefits of this new kind of disease modifying drugs for the future therapy of AD are discussed in this paper.

A 24-week, randomized, double-blind, placebo-controlled study to evaluate the efficacy, safety and tolerability of the rivastigmine patch in Japanese patients with Alzheimer's disease

Background

As of 2010, the rivastigmine patch was licensed for the treatment of Alzheimer's disease (AD) in 64 countries.

Methods

This 24-week, multicenter, randomized, double-blind, placebo-controlled study evaluated the efficacy, safety and tolerability of the 5-cm² (9-mg loading dose; 4.6 mg/24 h delivery rate) and 10-cm² (18-mg loading dose; 9.5 mg/24 h delivery rate) rivastigmine patch in Japanese patients with AD.

Results

In the primary analysis population (intent-to-treat last observation carried forward) at week 24, delayed deterioration was seen with the 10-cm² patch versus placebo on the Japanese version of the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-J cog; p = 0.005) and the Japanese version of the Clinician's Interview-Based Impression of Change plus Caregiver Input (CIBIC plus-J; p = 0.067). Participants receiving the rivastigmine patch showed numerically less decline versus placebo at week 24 on the CIBIC plus-J, although this did not reach statistical significance. Statistical significance for the CIBIC plus-J was met following adjustment for body weight and baseline Mini-Mental State Examination score as dynamic allocation factors (p = 0.042) and on the Disability Assessment for Dementia (DAD; p = 0.024) and Mental Function Impairment (MENFIS; p = 0.016) subscales. Serious adverse events were rare and were consistent with the known safety profile of the rivastigmine patch. Conclusion: The rivastigmine patch has a favorable efficacy and tolerability profile in Japanese patients with AD.

BMP9 protects septal neurons from axotomy-evoked loss of cholinergic phenotype

Background

Cholinergic projection from the septum to the hippocampus is crucial for normal cognitive function and degeneration of cells and nerve fibers within the septohippocampal pathway contributes to the pathophysiology of Alzheimer's disease. Bone morphogenetic protein (BMP) 9 is a cholinergic differentiating factor during development both in vivo and in vitro.

Methodology/Principal Findings

To determine whether BMP9 could protect the adult cholinergic septohippocampal pathway from axotomy-evoked loss of the cholinergic phenotype, we performed unilateral fimbria-fornix transection in mice and treated them with a continuous intracerebroventricular infusion of BMP9 for six days. The number of choline acetyltransferase (CHAT)-positive cells was reduced by 50% in the medial septal nucleus ipsilateral to the lesion as compared to the intact, contralateral side, and BMP9 infusion prevented this loss in a dose-dependent manner. Moreover, BMP9 prevented most of the decline of hippocampal acetylcholine levels ipsilateral to the lesion, and markedly increased CHAT, choline transporter CHT, NGF receptors p75 (NGFR-p75) and TrkA (NTRK1), and NGF protein content in both the lesioned and unlesioned hippocampi. In addition, BMP9 infusion reduced bilaterally hippocampal levels of basic FGF (FGF2) protein.

Conclusions/Significance

These data indicate that BMP9 administration can prevent lesion-evoked impairment of the cholinergic septohippocampal neurons in adult mice and, by inducing NGF, establishes a trophic environment for these cells.

Using MRI neuroimaging methods to detect treatment responses in Alzheimer’s disease

SUMMARY The rapid development of neuroimaging outcome measures for monitoring treatment effects and disease progression in neurological disorders presents both opportunities and hazards. An overview of functional MRI studies of regional brain activation using cognitive activation and resting state paradigms in mild cognitive impairment and Alzheimer’s disease indicates that this method can detect group treatment responses in the absence of overt behavioral change, as well as the kinetic and dynamic effects of the available symptomatic treatment compounds. Structural and spectroscopic MRI methods offer the prospect of objective and clinically meaningful assessment of progressive neuropathological changes and their modification through intervention. Including imaging parameters adequately powers small group studies of drug effects with additional advantages for more robust patient characterization and staging. These techniques should play an increasingly important role at an earlier stage of treatment evaluation, but the need for expert implementation and analysis means that clinical applications in individual cases are still in development.

Bapineuzumab

IMPORTANCE OF THE FIELD

Alzheimer's disease is the leading cause of dementia in the elderly, and there is no disease-modifying therapy yet available. Immunotherapy directed against the beta-amyloid peptide may be capable of slowing the rate of disease progression. Bapineuzumab, an anti-beta-amyloid monoclonal antibody, will be the first such agent to emerge from Phase III clinical trials.

AREAS COVERED IN THIS REVIEW

The primary literature on bapineuzumab from 2009 and 2010 is reviewed in its entirety, along with the literature on AN1792, a first-generation anti-beta-amyloid vaccine, from 2003 to 2009. Other Alzheimer's disease immunotherapeutics currently in development, according to www.clinicaltrials.gov , are also discussed.

WHAT THE READER WILL GAIN

In addition to a critical appraisal of the Phase II trial results for bapineuzumab, this review considers the broader field of immunotherapy for Alzheimer's disease as a whole, including the challenges ahead.

TAKE HOME MESSAGE

Bapineuzumab appears capable of reducing the cerebral beta-amyloid peptide burden in patients with Alzheimer's disease. However, particularly in APOE 4 carriers, its ability to slow disease progression remains uncertain, and vasogenic edema - a dose-limiting and potentially severe adverse reaction - may limit its clinical applicability.