The role of amyloid β in the pathogenesis of Alzheimer's disease

Murine Non-Transgenic Models of Alzheimer's Disease Pathology: Focus on Risk Factors

Alzheimer's disease (AD) represents a significant challenge among neurodegenerative disorders, as effective treatments and therapies remain largely undeveloped. Despite extensive research efforts employing various methodologies and diverse genetic models focused on amyloid-β (Aβ) pathology, the research for effective therapeutic strategies remains inconclusive. The key pathological features of AD include Aβ senile plaques, neurofibrillary tangles (NFTs), and the activation of neuroinflammatory pathways. Presently, investigations into AD and assessing potential treatments predominantly utilize Aβ transgenic models. Conversely, non-transgenic models may provide valuable insights into the multifaceted pathological states associated with AD. Thus, these models may serve as practical complementary tools for evaluating therapeutic and intervention strategies, since the primary AD risk factors are most frequently modeled. This review aims to critically assess the existing literature on AD non-transgenic models induced by streptozotocin, scopolamine, aging, mechanical stress, metals, and dietary patterns to enhance their application in AD research.

The Cerebrospinal Fluid Free-Glycans Hex1 and HexNAc1Hex1Neu5Ac1 as Potential Biomarkers of Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting a growing number of elderly people. In order to improve the early and differential diagnosis of AD, better biomarkers are needed. Glycosylation is a protein post-translational modification that is modulated in the course of many diseases, including neurodegeneration. Aiming to improve AD diagnosis and differential diagnosis through glycan analytics methods, we report the glycoprotein glycome of cerebrospinal fluid (CSF) isolated from a total study cohort of 262 subjects. The study cohort consisted of patients with AD, healthy controls and patients suffering from other types of dementia. CSF free-glycans were also isolated and analyzed in this study, and the results reported for the first time the presence of 19 free glycans in this body fluid. The free-glycans consisted of complete or truncated N-/O-glycans as well as free monosaccharides. The free-glycans Hex1 and HexNAc1Hex1Neu5Ac1 were able to discriminate AD from controls and from patients suffering from other types of dementia. Regarding CSF N-glycosylation, high proportions of high-mannose, biantennary bisecting core-fucosylated N-glycans were found, whereby only about 20% of the N-glycans were sialylated. O-Glycans and free-glycan fragments were less sialylated in AD patients than in controls. To conclude, this comprehensive study revealed for the first time the biomarker potential of free glycans for the differential diagnosis of AD.

Dose-dependent binding behavior of anthraquinone derivative purpurin interacting with tau-derived peptide protofibril

Alzheimer's disease is hallmarked by microtubule-associated protein tau tangles and amyloid-β plaques. The β-structure propensity of tau inclusions is closely related to the hexapeptide motif VQIVYK (termed PHF6), and disruption of this motif prevents tau aggregation. Small-molecule inhibitors are considered a promising therapeutic strategy, but the molecular mechanisms underlying the correlation between dose and inhibitory effects are still unclear. In this work, we investigated the dose-induced influence of purpurin, an anthraquinone derivative, on the structural stability of the PHF6 fibrillar nucleus by performing microsecond all-atom molecular dynamics simulations in explicit water. The stability of PHF6 protofibrils of different sizes was first examined, and it was found that the structural stability of fibrillar oligomers increases with oligomer size, and that the octamer is the minimal stable nucleus for fibril formation. When purpurin molecules were added to the protofibril octamer at a low purpurin/peptide ratio, they bound to the octamer with different coupling states, and the different states may transition to each of the other states through an uncoupling state or directly through a short-time transition. With increasing purpurin/peptide ratio, purpurins tend to self-aggregate rather than bind to the protein surface. Interestingly, the contacts between individual purpurins and the octamer as a function of the purpurin number show a power-law behavior, which may serve as a useful indicator to reflect the binding efficiency of ligands to proteins in drug screening. The interaction analysis reveals that purpurin prefers to bind to the hydrophilic and aromatic Tyr and has the lowest probability with the hydrophobic Val located in the middle of PHF6. Aromatic stacking plays a key role in the octamer-purpurin interaction, in which the three aromatic rings of purpurin have different contributions. In addition, purpurin shows a remarkable disruptive effect on the protofibril octamer when the molar ratio of purpurin to peptide is 1 : 2; above this ratio, the binding mode and disruption effect of purpurin do not change significantly. Our work provides a detailed picture of the dynamics and interactions of purpurin binding to the PHF6 protofibril and expands the understanding of the dose-induced inhibitory mechanism.

Effect of β-amyloid on blood-brain barrier properties and function

The deposition of beta-amyloid (Aβ) aggregates in the brain, accompanied by impaired cognitive function, is a characteristic feature of Alzheimer's disease (AD). An important role in this process is played by vascular disorders, in particular, a disturbance of the blood-brain barrier (BBB). The BBB controls the entry of Aβ from plasma to the brain via the receptor for advanced glycation end products (RAGE) and the removal of brain-derived Aβ via the low-density lipoprotein receptor-related protein (LRP1). The balance between the input of Aβ to the brain from the periphery and its output is disturbed during AD. Aβ changes the redox-status of BBB cells, which in turn changes the functioning of mitochondria and disrupts the barrier function of endothelial cells by affecting tight junction proteins. Aβ oligomers have the greatest toxic effect on BBB cells, and oligomers are most rapidly transferred by transcytosis from the brain side of the BBB to the blood side. Both the cytotoxic effect of Aβ and the impairment of barrier function are partly due to the interaction of Aβ monomers and oligomers with membrane-bound RAGE. AD therapies based on the disruption of this interaction or the creation of decoys for Aβ are being developed. The question of the transfer of various Aβ isoforms through the BBB is important, since it can influence the development of AD. It is shown that the rate of input of Aβ40 and Aβ42 from the blood into the brain is different. The actual question of the transfer of pathogenic Aβ isoforms with post-translational modifications or mutations through the BBB still remains open.

Emphasizing roles of BDNF promoters and inducers in Alzheimer's disease for improving impaired cognition and memory

Brain-derived neurotrophic factor (BDNF) is a crucial neurotrophic factor adding to neurons' development and endurance. The amount of BDNF present in the brain determines susceptibility to various neurodegenerative diseases. In Alzheimer's disease (AD), often it is seen that low levels of BDNF are present, which primarily contributes to cognition deficit by regulating long-term potentiation (LTP) and synaptic plasticity. Molecular mechanisms underlying the synthesis, storage and release of BDNF are widely studied. New molecules are found, which contribute to the signal transduction pathway. Two important receptors of BDNF are TrkB and p75NTR. When BDNF binds to the TrkB receptor, it activates three main signalling pathways-phospholipase C, MAPK/ERK, PI3/AKT. BDNF holds an imperative part in LTP and dendritic development, which are essential for memory formation. BDNF supports synaptic integrity by influencing LTP and LTD. This action is conducted by modulating the glutamate receptors; AMPA and NMDA. This review paper discusses the aforesaid points along with inducers of BDNF. Drugs and herbals promote neuroprotection by increasing the hippocampus' BDNF level in various disease-induced animal models for neurodegeneration. Advancement in finding pertinent molecules contributing to the BDNF signalling pathway has been discussed, along with the areas that require further research and study.

Dissecting genetic links between Alzheimer’s disease and type 2 diabetes mellitus in a systems biology way

Background: Alzheimer’s disease (AD) and Type 2 Diabetes Mellitus (T2DM) are two of the most common diseases for older adults. Accumulating epidemiological studies suggest that T2DM is a risk factor for cognitive dysfunction in the elderly. In this study, we aimed to dissect the genetic links between the two diseases and identify potential genes contributing the most to the mechanistic link.

Methods: Two AD (GSE159699 and GSE28146) and two T2DM (GSE38642 and GSE164416) datasets were used to identify the differentially expressed genes (DEGs). The datasets for each disease were detected using two platforms, microarray and RNA-seq. Functional similarity was calculated and evaluated between AD and T2DM DEGs considering semantic similarity, protein-protein interaction, and biological pathways.

Results: We observed that the overlapped DEGs between the two diseases are not in a high proportion, but the functional similarity between them is significantly high when considering Gene Ontology (GO) semantic similarity and protein-protein interactions (PPIs), indicating that T2DM shares some common pathways with AD development. Moreover, we constructed a PPI network consisting of AD and T2DM DEGs, and found that the hub gene SLC2A2 (coding transmembrane carrier protein GLUT2), which connects the most DEGs in both AD and T2DM, plays as a key regulator in linking T2DM and AD via glucose metabolism related pathways.

Conclusion: Through functional evaluation at the systems biology level, we demonstrated that AD and T2DM are similar diseases sharing common pathways and pathogenic genes. SLC2A2 may serve as a potential marker for early warning and monitoring of AD for the T2DM patients.

Systemic Inflammation Predicts Alzheimer Pathology in Community Samples without Dementia

Neuroinflammation and oxidative stress (OS) are implicated in the pathophysiology of Alzheimer’s disease (AD). However, it is unclear at what stage of the disease process inflammation first becomes manifest. The aim of this study was to investigate the associations between specific plasma markers of inflammation and OS, tau, and Amyloid-β 38, 40, and 42 levels in cognitively unimpaired middle-age and older individuals. Associations between inflammatory states identified through principal component analysis and AD biomarkers were investigated in middle-age (52–56 years, n = 335, 52% female) and older-age (72–76 years, n = 351, 46% female) participants without dementia. In middle-age, a component reflecting variation in OS was most strongly associated with tau and to a lesser extent amyloid-β levels. In older-age, a similar component to that observed in middle-age was only associated with tau, while another component reflecting heightened inflammation independent of OS, was associated with all AD biomarkers. In middle and older-age, inflammation and OS states are associated with plasma AD biomarkers.

Diet Patterns, the Gut Microbiome, and Alzheimer's Disease

Given the complex bidirectional communication system that exists between the gut microbiome and the brain, there is growing interest in the gut microbiome as a novel and potentially modifiable risk factor for Alzheimer's disease (AD). Gut dysbiosis has been implicated in the pathogenesis and progression of AD by initiating and prolonging neuroinflammatory processes. The metabolites of gut microbiota appear to be critical in the mechanism of the gut-brain axis. Gut microbiota metabolites, such as trimethylamine-n-oxide, lipopolysaccharide, and short chain fatty acids, are suggested to mediate systemic inflammation and intracerebral amyloidosis via endothelial dysfunction. Emerging data suggest that the fungal microbiota (mycobiome) may also influence AD pathology. Importantly,  60% of variation in the gut microbiome is attributable to diet, therefore modulating the gut microbiome through dietary means could be an effective approach to reduce AD risk. Given that people do not eat isolated nutrients and instead consume a diverse range of foods and combinations of nutrients that are likely to be interactive, studying the effects of whole diets provides the opportunity to account for the interactions between different nutrients. Thus, dietary patterns may be more predictive of real-life effect on gut microbiome and AD risk than foods or nutrients in isolation. Accumulating evidence from experimental and animal studies also show potential effects of gut microbiome on AD pathogenesis. However, data from human dietary interventions are lacking. Well-designed intervention studies are needed in diverse populations to determine the influence of diet on gut microbiome and inform the development of effective dietary strategies for prevention of AD.

Severe tauopathy and axonopathy in the medulla oblongata in Alzheimer's disease implicate the changes in autonomic nervous function

The autonomic dysfunctions in Alzheimer's disease (AD) have been identified from many clinical studies, however, there is still a lack of evidence directly verifying the structural abnormalities of the autonomic nervous system in AD. Human medulla oblongatas from four AD patients or five non-AD subjects were obtained and observed by using immunohistochemical staining of hyperphosphorylated tau and Aβ amyloid, and post-mortem tracing techniques. We found distinct axonal and somatic immunoreactivities for the tau markers AT8 and Tau-5 in the different areas of the medulla oblongata in AD patients, which was particularly obvious in the dorsal nucleus of the vagus nerve, the nucleus of the solitary tract and the reticular nucleus. The swollen axons, which are a typical feature of axonopathy, were not only identified in the axons with immunohistochemical labeling of AT8 and Tau-5 in the different nuclei of the medulla oblongata, but also in the tracer-labeled afferent and efferent fibres of the vagus nerve in AD patients. Such changes in tauopathy and axonopathy were only occasionally found in the non-AD aged subjects. Interestingly, we did not observe any intra- or extracellular Aβ deposits in the medulla oblongatas of the AD patients or of the non-AD subjects. These results in small samples suggest that occurrence of tauopathy and axonopathy in the parasympathetic nuclei of the medulla oblongata in AD patients may implicate the change of autonomic nervous function.

Advanced Biomaterials for Cell-Specific Modulation and Restore of Cancer Immunotherapy

The past decade has witnessed the explosive development of cancer immunotherapies. Nevertheless, low immunogenicity, limited specificity, poor delivery efficiency, and off-target side effects remain to be the major limitations for broad implementation of cancer immunotherapies to patient bedside. Encouragingly, advanced biomaterials offering cell-specific modulation of immunological cues bring new solutions for improving the therapeutic efficacy while relieving side effect risks. In this review, focus is given on how functional biomaterials can enable cell-specific modulation of cancer immunotherapy within the cancer-immune cycle, with particular emphasis on antigen-presenting cells (APCs), T cells, and tumor microenvironment (TME)-resident cells. By reviewing the current progress in biomaterial-based cancer immunotherapy, here the aim is to provide a better understanding of biomaterials' role in targeting modulation of antitumor immunity step-by-step and guidelines for rationally developing targeting biomaterials for more personalized cancer immunotherapy. Moreover, the current challenge and future perspective regarding the potential application and clinical translation will also be discussed.

Discovery of PT-65 as a highly potent and selective Proteolysis-targeting chimera degrader of GSK3 for treating Alzheimer's disease

GSK3 is a promising target for the treatment of Alzheimer's disease. Here, we describe the design and synthesize of a series of GSK3 degraders based on a click chemistry platform. A series of highly potent GSK3 degraders were obtained. Among them, PT-65 exhibited most potent degradation potency against GSK3α (DC₅₀ = 28.3 nM) and GSK3β (DC₅₀ = 34.2 nM) in SH-SY5Y cells. SPR assay confirmed that PT-65 binds to GSK3β with high affinity (K_D = 12.41 nM). The proteomic study indicated that PT-65 could selectively induced GSK3 degradation. Moreover, PT-65 could effectively suppress GSK3β and Aβ mediated tau hyperphosphorylation in a dose-dependent manner and protect SH-SY5Y cells from Aβ caused cell damage. We also confirmed that PT-65 could suppress OA induced tau hyperphosphorylation and ameliorate learning and memory impairments in vivo model of AD. In summary, PT-65 might be a promising candidate for the treatment of AD.

Lactobacillus plantarum PS128 prevents cognitive dysfunction in Alzheimer's disease mice by modulating propionic acid levels, glycogen synthase kinase 3 beta activity, and gliosis

Background

According to recent evidence, psychobiotics exert beneficial effects on central nervous system-related diseases, such as mental disorders. Lactobacillus plantarum PS128 (PS128), a novel psychobiotic strain, improves motor function, depression, and anxiety behaviors. However, the psychobiotic effects and mechanisms of PS128 in Alzheimer’s disease (AD) remain to be explored.

Objectives

The goal of the current study was to evaluate the beneficial effects of PS128 and to further elucidate its mechanism in AD mice.

Methods

PS128 (10¹⁰ colony-forming unit (CFU)/ml) was administered via oral gavage (o.g.) to 6-month-old male wild-type B6 and 3 × Tg-AD mice (harboring the PS1M146V, APPswe and TauP30IL transgenes) that received an intracerebroventricular injection of streptozotocin (icv-STZ, 3 mg/kg) or vehicle (saline) for 33 days. After serial behavioral tests, fecal short-chain fatty acid levels and AD-related pathology were assessed in these mice.

Results

Our findings show that intracerebroventricular injection of streptozotocin accelerated cognitive dysfunction associated with increasing levels of glycogen synthase kinase 3 beta (GSK3β) activity, tau protein phosphorylation at the T231 site (pT231), amyloid-β (Aβ) deposition, amyloid-β protein precursor (AβPP), β-site AβPP-cleaving enzyme (BACE1), gliosis, fecal propionic acid (PPA) levels and cognition-related neuronal loss and decreasing postsynaptic density protein 95 (PSD95) levels in 3 × Tg-AD mice. PS128 supplementation effectively prevented the damage induced by intracerebroventricular injection of streptozotocin in 3 × Tg-AD mice.

Conclusions

Based on the experimental results, intracerebroventricular injection of streptozotocin accelerates the progression of AD in the 3 × Tg-AD mice, primarily by increasing the levels of gliosis, which were mediated by the propionic acid and glycogen synthase kinase 3 beta pathways. PS128 supplementation prevents damage induced by intracerebroventricular injection of streptozotocin by regulating the propionic acid levels, glycogen synthase kinase 3 beta activity, and gliosis in 3 × Tg-AD mice. Therefore, we suggest that PS128 supplementation is a potential strategy to prevent and/or delay the progression of AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03426-8.

Brain energy metabolism in intracerebroventricularly administered streptozotocin mouse model of Alzheimer's disease: A 1H-[13C]-NMR study

Alzheimer's disease (AD) is a very common neurodegenerative disorder. Although a majority of the AD cases are sporadic, most of the studies are conducted using transgenic models. Intracerebroventricular (ICV) administered streptozotocin (STZ) animals have been used to explore mechanisms in sporadic AD. In this study, we have investigated memory and neurometabolism of ICV-STZ-administered C57BL6/J mice. The neuronal and astroglial metabolic activity was measured in ¹H-[¹³C]-NMR spectrum of cortical and hippocampal tissue extracts of mice infused with [1,6-¹³C₂]glucose and [2-¹³C]acetate, respectively. STZ-administered mice exhibited reduced (p = 0.00002) recognition index for memory. The levels of creatine, GABA, glutamate and NAA were reduced (p ≤ 0.04), while that of myo-inositol was increased (p < 0.05) in STZ-treated mice. There was a significant (p ≤ 0.014) reduction in aspartate-C3, glutamate-C4/C3, GABA-C2 and glutamine-C4 labeling from [1,6-¹³C₂]glucose. This resulted in decreased rate of glucose oxidation in the cerebral cortex (0.64 ± 0.05 vs. 0.77 ± 0.05 µmol/g/min, p = 0.0008) and hippocampus (0.60 ± 0.04 vs. 0.73 ± 0.07 µmol/g/min, p = 0.001) of STZ-treated mice, due to similar reductions of glucose oxidation in glutamatergic and GABAergic neurons. Additionally, reduced glutamine-C4 labeling points towards compromised synaptic neurotransmission in STZ-treated mice. These data suggest that the ICV-STZ model exhibits neurometabolic deficits typically observed in AD, and its utility in understanding the mechanism of sporadic AD.

Microenvironment-tailored nanoassemblies for the diagnosis and therapy of neurodegenerative diseases

Neurodegenerative disorder is an illness involving neural dysfunction/death attributed to complex pathological processes, which eventually lead to the mortality of the host. It is generally recognized through features such as mitochondrial dysfunction, protein aggregation, oxidative stress, metal ions dyshomeostasis, membrane potential change, neuroinflammation and neurotransmitter impairment. The aforementioned neuronal dysregulations result in the formation of a complex neurodegenerative microenvironment (NME), and may interact with each other, hindering the performance of therapeutics for neurodegenerative disease (ND). Recently, smart nanoassemblies prepared from functional nanoparticles, which possess the ability to interfere with different NME factors, have shown great promise to enhance the diagnostic and therapeutic efficacy of NDs. Herein, this review highlights the recent advances of stimuli-responsive nanoassemblies that can effectively combat the NME for the management of ND. The first section outlined the NME properties and their interrelations that are exploitable for nanoscale targeting. The discussion is then extended to the controlled assembly of functional nanoparticles for the construction of stimuli-responsive nanoassemblies. Further, the applications of stimuli-responsive nanoassemblies for the enhanced diagnosis and therapy of ND are introduced. Finally, perspectives on the future development of NME-tailored nanomedicines are given.

Alzheimer’s disease and type 2 diabetes mellitus: Pathophysiologic and pharmacotherapeutics links

At present, Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2DM) are two highly prevalent disorders worldwide, especially among elderly individuals. T2DM appears to be associated with cognitive dysfunction, with a higher risk of developing neurocognitive disorders, including AD. These diseases have been observed to share various pathophysiological mechanisms, including alterations in insulin signaling, defects in glucose transporters (GLUTs), and mitochondrial dysfunctions in the brain. Therefore, the aim of this review is to summarize the current knowledge regarding the molecular mechanisms implicated in the association of these pathologies as well as recent therapeutic alternatives. In this context, the hyperphosphorylation of tau and the formation of neurofibrillary tangles have been associated with the dysfunction of the phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways in the nervous tissues as well as the decrease in the expression of GLUT-1 and GLUT-3 in the different areas of the brain, increase in reactive oxygen species, and production of mitochondrial alterations that occur in T2DM. These findings have contributed to the implementation of overlapping pharmacological interventions based on the use of insulin and antidiabetic drugs, or, more recently, azeliragon, amylin, among others, which have shown possible beneficial effects in diabetic patients diagnosed with AD.

Transplantation of Mesenchymal Stem Cells Improves Amyloid-β Pathology by Modifying Microglial Function and Suppressing Oxidative Stress

Mesenchymal stem cells (MSC) are increasingly being studied as a source of cell therapy for neurodegenerative diseases, and several groups have reported their beneficial effects on Alzheimer’s disease (AD). In this study using AD model mice (APdE9), we found that transplantation of MSC via the tail vein improved spatial memory in the Morris water maze test. Using electron paramagnetic resonance imaging to evaluate the in vivo redox state of the brain, we found that MSC transplantation suppressed oxidative stress in AD model mice. To elucidate how MSC treatment ameliorates oxidative stress, we focused on amyloid-β (Aβ) pathology and microglial function. MSC transplantation reduced Aβ deposition in the cortex and hippocampus. Transplantation of MSC also decreased Iba1-positive area in the cortex and reduced activated ameboid shaped microglia. On the other hand, MSC transplantation accelerated accumulation of microglia around Aβ deposits and prompted microglial Aβ uptake and clearance as shown by higher frequency of Aβ-containing microglia. MSC transplantation also increased CD14-positive microglia in vivo, which play a critical role in Aβ uptake. To confirm the effects of MSC on microglia, we co-cultured the mouse microglial cell line MG6 with MSC. Co-culture with MSC enhanced Aβ uptake by MG6 cells accompanied by upregulation of CD14 expression. Additionally, co-culture of MG6 cells with MSC induced microglial phenotype switching from M1 to M2 and suppressed production of proinflammatory cytokines. These data indicate that MSC treatment has the potential to ameliorate oxidative stress through modification of microglial functions, thereby improving Aβ pathology in AD model mice.

Evaluation of Mitochondrial Oxidative Stress in the Brain of a Transgenic Mouse Model of Alzheimer's Disease by in vitro Electron Paramagnetic Resonance Spectroscopy

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases responsible for progressive dementia. Deposition of amyloid-β (Aβ) in the brain is the most important pathophysiological hallmark of AD. In addition, recent evidence indicates that reactive oxygen species (ROS) derived from mitochondria contribute to progression of AD pathology. We thus hypothesized that Aβ accumulates and oxidative stress increases in the brain mitochondria of a transgenic mouse model of AD (APdE9). We measured the quantity of Aβ and the activity of the antioxidant enzyme superoxide dismutase (SOD) in brain mitochondrial fractions prepared from APdE9 and wild-type (WT) mice aged 6, 9, 15, and 18 months. We also quantified the age-related changes in redox status in the mitochondrial fractions obtained from both APdE9 and WT mouse brains by electron paramagnetic resonance (EPR) spectrometry using a paramagnetic nitroxide "Mito-Tempo" [(2-(2,2,6,6-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride monohydrate] as a mitochondria-targeted redox-sensitive probe. In APdE9 mice, Aβ accumulated in brain mitochondria earlier than in the non-mitochondrial fraction of the brain. Furthermore, increased oxidative stress was demonstrated in brain mitochondria of APdE9 mice by in vitro SOD assay as well as EPR spectroscopy. EPR combined with a mitochondria-targeted redox-sensitive nitroxide probe is a potentially powerful tool to elucidate the etiology of AD and facilitate the development of new therapeutic strategies for AD.

Breviscapine exerts neuroprotective effects through multiple mechanisms in APP/PS1 transgenic mice

Alzheimer's disease (AD) is one of the most serious neurodegenerative diseases and is characterized by progressive cognitive impairment and multiple neurological changes. To date, there are no effective drugs to delay or cure AD. Breviscapine (Bre) is an active ingredient of flavonoids extracted from breviscapus. Previous research suggests that Bre is an effective medicine for the prevention and treatment of AD. In the present study, we sought to explore the molecular mechanisms responsible for short-term beneficial effects of Breviscapine on Aβ burden, neuronal and synaptic, cognitive function in APP/PS1 transgenic mice at 6 months age. Our results showed that 3 months of intraperitoneal treatment with Bre rescued learning deficits, relieved memory retention, improved the ability to explore the outside world, markedly decreased Aβ burden, attenuated function of neocortical and hippocampal neuron, and increased the synaptic proteins levels in the brain of APP/PS1 mice by decreasing BACE1, promoting Aβ-degrading enzyme IDE expression, suppressing RAGE expression, and regulating p38/p53/NT4 pathway. This finding provides more evidence of neuroprotective effects and action mechanisms of Bre antagonist AD, suggesting that Bre may have potential as anti-AD agent.

Meclizine ameliorates memory deficits in streptozotocin-induced experimental dementia in mice: role of nuclear pregnane X receptors

Pregnane X receptors (PXRs) regulate the expression of ATP-binding cassette proteins transporters and organic anion transporting polypeptides responsible for influx/efflux of xenobiotics across the brain. Ligand activation of PXR augments the expression of P-gp and promotes amyloid-β clearance across the blood-brain barrier. Dementia was induced in mice by intacerebroventricular administration of streptozotocin (STZ) followed by treatment with meclizine, a PXR agonist, and subsequently exposed to the Morris water maze test and biochemical and histopathological analysis to evaluate the effect on cognition. STZ-treated mice exhibited significant enhancement in brain thiobarbituric acid reactive species, interleukin-1β, tumour necrosis factor-α, myeloperoxidase, and acetylcholinestrase activity in addition to diminution in glutathione levels and superoxide dismutase activity in comparison to untreated mice. Administration of meclizine to STZ mice recuperated cognition and biochemical alterations. Concomitant administration of ketoconazole, a PXR antagonist, with meclizine prevented the protective effects. The upshots of our study proclaim that meclizine protects cognitive deficits by virtue of its antioxidant, anticholinesterase, and antiinflammatory properties. Results also signify the potential of PXR in neuroprotective actions of meclizine in dementia.

The neuroprotective effect of agmatine against amyloid β-induced apoptosis in primary cultured hippocampal cells involving ERK, Akt/GSK-3β, and TNF-α

β-Amyloid peptide (Aβ), the major element of senile plaques in Alzheimer's disease (AD), has been found to accumulate in brain regions critical for memory and cognition. Deposits of Aβ trigger neurotoxic events which lead to neural apoptotic death. The present study examined whether agmatine, an endogenous polyamine formed by the decarboxylation of L-arginine, possesses a neuroprotective effect against Aβ-induced toxicity. Primary rat hippocampal cells extracted from the brains of 18-19-day-old embryos were exposed to 10 µM of Aβ (25-35) in the absence or presence of agmatine at 150 or 250 µM. Additionally, the involvement of Akt (Protein Kinae B), GSK-3β (glycogen synthase kinase 3-β), ERK (Extracellular Signal-Regulated Kinase) and TNF-α (Tumor necrosis factor-α) in the agmatine protection against Aβ-induced neurotoxicity was investigated. Agmatine significantly prevented the effect of Aβ exposure on cell viability and caspase-3 assays. Furthermore, agmatine considerably restored Aβ-induced decline of phospho-Akt and phospho-GSK and blocked Aβ-induced increase of phospho-ERK and TNF-alpha. Taken together, these findings might shed light on the protective effect of agmatine as a potential therapeutic agent for AD.

Membrane-Modulating Drugs can Affect the Size of Amyloid-β25-35 Aggregates in Anionic Membranes

The formation of amyloid-β plaques is one of the hallmarks of Alzheimer's disease. The presence of an amphiphatic cell membrane can accelerate the formation of amyloid-β aggregates, making it a potential druggable target to delay the progression of Alzheimer's disease. We have prepared unsaturated anionic membranes made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS) and added the trans-membrane segment Aβ_25-35. Peptide plaques spontaneously form in these membranes at high peptide concentrations of 20 mol%, which show the characteristic cross-β motif (concentrations are relative to the number of membrane lipids and indicate the peptide-to-lipid ratio). We used atomic force microscopy, fluorescence microscopy, x-ray microscopy, x-ray diffraction, UV-vis spectroscopy and Molecular Dynamics (MD) simulations to study three membrane-active molecules which have been speculated to have an effect in Alzheimer's disease: melatonin, acetylsalicyclic acid (ASA) and curcumin at concentrations of 5 mol% (drug-to-peptide ratio). Melatonin did not change the structural parameters of the membranes and did not impact the size or extent of peptide clusters. While ASA led to a membrane thickening and stiffening, curcumin made membranes softer and thinner. As a result, ASA was found to lead to the formation of larger peptide aggregates, whereas curcumin reduced the volume fraction of cross-β sheets by ~70%. We speculate that the interface between membrane and peptide cluster becomes less favorable in thick and stiff membranes, which favors the formation of larger aggregates, while the corresponding energy mismatch is reduced in soft and thin membranes. Our results present evidence that cross-β sheets of Aβ_25-35 in anionic unsaturated lipid membranes can be re-dissolved by changing membrane properties to reduce domain mismatch.

Stability analysis of a steady state of a model describing Alzheimer's disease and interactions with prion proteins

Alzheimer's disease (AD) is a neuro-degenerative disease affecting more than 46 million people worldwide in 2015. AD is in part caused by the accumulation of A[Formula: see text] peptides inside the brain. These can aggregate to form insoluble oligomers or fibrils. Oligomers have the capacity to interact with neurons via membrane receptors such as prion proteins ([Formula: see text]). This interaction leads [Formula: see text] to be misfolded in oligomeric prion proteins ([Formula: see text]), transmitting a death signal to neurons. In the present work, we aim to describe the dynamics of A[Formula: see text] assemblies and the accumulation of toxic oligomeric species in the brain, by bringing together the fibrillation pathway of A[Formula: see text] peptides in one hand, and in the other hand A[Formula: see text] oligomerization process and their interaction with cellular prions, which has been reported to be involved in a cell-death signal transduction. The model is based on Becker-Döring equations for the polymerization process, with delayed differential equations accounting for structural rearrangement of the different reactants. We analyse the well-posedness of the model and show existence, uniqueness and non-negativity of solutions. Moreover, we demonstrate that this model admits a non-trivial steady state, which is found to be globally stable thanks to a Lyapunov function. We finally present numerical simulations and discuss the impact of model parameters on the whole dynamics, which could constitute the main targets for pharmaceutical industry.

Application of nanodiagnostics and nanotherapy to CNS diseases

Alzheimer's disease, Parkinson's disease and stroke are the most common CNS diseases, all characterized by progressive cellular dysfunction and death in specific areas of the nervous system. Therapeutic development for these diseases has lagged behind other disease areas due to difficulties in early diagnosis, long disease courses and drug delivery challenges, not least due to the blood-brain barrier. Over recent decades, nanotechnology has been explored as a potential tool for the diagnosis, treatment and monitoring of CNS diseases. In this review, we describe the application of nanotechnology to common CNS diseases, highlighting disease pathogenesis and the underlying mechanisms and promising functional outcomes that make nanomaterials ideal candidates for early diagnosis and therapy. Moreover, we discuss the limitations of nanotechnology, and possible solutions.

Design of Diarylheptanoid Derivatives as Dual Inhibitors Against Class IIa Histone Deacetylase and β-amyloid Aggregation

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder with multiple etiologies. Beta-amyloid (Aβ) self-aggregation and overexpression of class IIa histone deacetylases (HDACs) are strongly implicated with AD pathogenesis. In this study, a series of novel diarylheptanoid derivatives were designed, synthesized and evaluated for use as dual Aβ self-aggregation and class IIa HDAC inhibitors. Among these compounds, 4j, 5c, and 5e displayed effective inhibitions for Aβ self-aggregation, HDAC5 activity and HDAC7 activity with IC₅₀ values of <10 μM. The compounds contain three common features: (1) a catechol or pyrogallol moiety, (2) a carbonyl linker and (3) an aromatic ring that can function as an HDAC cap and create hydrophobic interactions with Aβ_1-42. Furthermore, compounds 4j, 5c, and 5e showed no significant cytotoxicity to human neuroblastoma SH-SY5Y cells and also exhibited neuroprotective effect against H₂O₂-induced toxicity. Overall, these promising in vitro data highlighted compounds 4j, 5c, and 5e as lead compounds that are worthy for further investigation.

Protective Effects of Fibroblast Growth Factor 21 Against Amyloid-Beta1-42-Induced Toxicity in SH-SY5Y Cells

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the progressive loss of cholinergic neurons. Amyloid beta is a misfolded protein that represents one of the key pathological hallmarks of AD. Numerous studies have shown that Aβ_1-42 induces oxidative damage, neuroinflammation, and apoptosis, leading to cognitive decline in AD. Recently, fibroblast growth factor 21 (FGF21) has been suggested to be a potential regulator of oxidative stress in mammalian cells. FGF21 has been shown to improve insulin sensitivity, reduce hyperglycemia, increase adipose tissue glucose uptake and lipolysis, and decrease body fat and weight loss by enhancing energy expenditure. In this study, we investigated the effect of FGF21 Aβ_1-42 toxicity in SH-SY5Y neuroblastoma cells. Our data shows that FGF21 significantly decreased Aβ_1-42-induced toxic effects and repressed oxidative stress and apoptosis in cells exposed to Aβ_1-42 peptide. Our investigation also confirmed that FGF21 pretreatment favorably affects HSP90/TLR4/NF-κB signaling pathway. Therefore, FGF21 represents a viable therapeutic strategy to abrogate Aβ_1-42-induced cellular inflammation and apoptotic death in the SH-SY5Y neuroblastoma cells.

Improved synaptic and cognitive function in aged 3 × Tg-AD mice with reduced amyloid-β after immunotherapy with a novel recombinant 6Aβ15-TF chimeric vaccine

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder impairing memory and cognition. In this study, we describe the immunogenicity and protective efficacy of the novel recombinant 6Aβ15-TF chimeric antigen as a subunit protein vaccine for AD. Recombinant 6Aβ15-TF chimeric vaccine induced strong Aβ-specific humoral immune responses without Aβ-specific T cell immunity in C57/BL6 and 3 × Tg-AD mice at different ages. As an early immunotherapy model for AD, this vaccine induced high titers of long-lasting anti-Aβ42 antibodies in aged 3 × Tg-AD mice, which led to improve behavioral performance and markedly reduced the levels of insoluble and soluble Aβ and Aβ oligomers. In agreement with these findings, immunotherapy with 6Aβ15-TF prevented the Aβ-induced decrease of presynaptic and postsynaptic proteins in aged 3 × Tg-AD mice. Our results suggest that this novel and highly immunogenic recombinant 6Aβ15-TF chimeric vaccine provides neuroprotection in AD mice and can be considered an effective AD candidate vaccine.

1,2,4-trihydroxynaphthalene-2-O-β-D-glucopyranoside delays amyloid-β42 aggregation and reduces amyloid cytotoxicity

Presently, misfolding and aggregation of amyloid-β₄₂ (Aβ₄₂ ) are considered early events in Alzheimer's disease (AD) pathogenesis. The use of natural products to inhibit the aggregation process and to protect cells from cytotoxicity of early aggregate grown at the onset of the aggregation path is one of the promising strategies against AD. Recently, we have purified a new powerful antioxidant and inhibitor of Aβ₄₂ aggregation from the leaves of Lawsonia inermis. The new compound was identified as a new Lawsoniaside; 1,2,4-trihydroxynaphthalene-2-O-β-D-glucopyranoside (THNG). Herein, we show that THNG interferes with Aβ₄₂ aggregation, inhibits its conformational change to a β-sheet-rich structure, decreases its polymerization into large fibrillar species, reduces oxidative stress, and aggregate cytotoxicity. These results indicate that THNG has great potential as a neuroprotective and therapeutic agent against AD. © 2018 BioFactors, 44(3):272-280, 2018.

Nutraceuticals: An emerging therapeutic approach against the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is regarded as a progressive and devastating neurodegenerative disorder. In aged individuals, it is the most prevalent cause of dementia and is characterized by gradual loss of cognitive functions. In the last decade, numerous research works were undertaken to investigate the pathogenesis of AD. Although the etiology of AD is still not clear, several histopathological studies confirm prominent changes in the AD affected brains. The major changes include the formation of senile plaques and neurofibrillary tangles primarily owing to the deposition of amyloid β plaques (Aβ) and hyper-phosphorylation of tau protein. Disruption of the redox homeostasis in the brain is a major triggering factor for the development of such pathophysiological conditions. Chemical formulations usually act by inhibiting activities of the enzymes responsible for the development of AD. But with time, these pharmacotherapies develop many side effects including toxicity in different organs. Recent researches are henceforth focused on the identification of novel therapeutic molecules from the nature's basket. This review aims to emphasize the therapeutic effects and regulation of molecular targets of different natural products such as curcumin, resveratrol, genistein and others. These prophylactic multipotent natural compounds have the potency to interfere with the formation as well as deposition of the Aβ peptides. These natural compounds have also been found in modulating different intracellular signalling molecules and enzymes including β-secretase and γ-secretase. This review article is expected to be helpful in understanding the recent progress in natural product research as a therapeutic approach in amelioration and/or delaying the detrimental effects of AD.

The pro-apoptotic protein Bmf co-operates with Bim and Puma in neuron death induced by β-amyloid or NGF deprivation

The pro-apoptotic Bcl-2 homology 3 domain only (BH3-only) proteins are central regulators of cell death in various physiological and pathological conditions, including Alzheimer's disease (AD). Bcl-2 modifying factor (Bmf) is one such BH3-only protein that is implicated in various death paradigms such as anoikis, seizures, cancer and autoimmunity. It also co-operates with other BH3-only proteins such as Bim in various death paradigms. However, its role in neurodegeneration is under-investigated. Here, we report for the first time the essential role of Bmf and its co-operativity with direct activator BH3-only proteins Bim and Puma in neuron death induced by beta-amyloid (Aβ) toxicity or NGF deprivation. Oligomeric Aβ is main pathologic species in AD and NGF deprivation is relevant for both developmental as well as pathologic neuron death. We find that Bmf over-expression causes cell death and Bmf knockdown protects neurons against death evoked by Aβ or NGF deprivation. We also find that Bmf co-operates with other important BH3-only proteins such as Bim and Puma in neuron death induced by Aβ or NGF deprivation. Simultaneous knocking down of these molecules by their respective shRNAs provide enhanced protection against Aβ. Taken together, our results elucidate the essential role of Bmf and its co-operative effects with already known neuron death inducers, Bim and Puma, in neuron death evoked by Aβ treatment or NGF deprivation.

Tau-Targeted Multifunctional Nanocomposite for Combinational Therapy of Alzheimer's Disease

Alzheimer's disease (AD) remains an incurable disease and lacks efficient diagnostic methods. Most AD treatments have focused on amyloid-β (Aβ) targeted therapy; however, it is time to consider the alternative theranostics due to accumulated findings of weak correlation between Aβ deposition and cognition, as well as the failures of Phase III clinical trial on Aβ targeted therapy. Recent studies have shown that the tau pathway is closely associated with clinical development of AD symptoms, which might be a potential therapeutic target. We herein construct a methylene blue (MB, a tau aggregation inhibitor) loaded nanocomposite (CeNC/IONC/MSN-T807), which not only possesses high binding affinity to hyperphosphorylated tau but also inhibits multiple key pathways of tau-associated AD pathogenesis. We demonstrate that these nanocomposites can relieve the AD symptoms by mitigating mitochondrial oxidative stress, suppressing tau hyperphosphorylation, and preventing neuronal death both in vitro and in vivo. The memory deficits of AD rats are significantly rescued upon treatment with MB loaded CeNC/IONC/MSN-T807. Our results indicate that hyperphosphorylated tau-targeted multifunctional nanocomposites could be a promising therapeutic candidate for Alzheimer's disease.

A Common Variant in the MC1R Gene (p.V92M) is associated with Alzheimer's Disease Risk

Despite the recent identification of some novel risk genes for Alzheimer's disease (AD), the genetic etiology of late-onset Alzheimer's disease (LOAD) remains largely unknown. The inclusion of these novel risk genes to the risk attributable to the APOE gene accounts for roughly half of the total genetic variance in LOAD. The evidence indicates that undiscovered genetic factors may contribute to AD susceptibility. In the present study, we sequenced the MC1R gene in 525 Spanish LOAD patients and in 160 controls. We observed that a common MC1R variant p.V92M (rs2228479), not related to pigmentation traits, was present in 72 (14%) patients and 15 (9%) controls and confers increased risk of developing LOAD (OR: 1.99, 95% CI: 1.08-3.64, p = 0.026), especially in those patients whose genetic risk could not be explained by APOE genotype. This association remains and even increased in the subset of 69 patients with typical AD cerebrospinal fluid profile (OR: 3.40 95% CI: 1.40-8.27, p = 0.007). We did not find an association between p.V92M and age of onset of AD. Further studies are necessary to elucidate the role of MC1R in brain cells through the different MC1R pathways.

Regulation of ADAM10 by miR-140-5p and potential relevance for Alzheimer's disease

Recent reports in Alzheimer's disease (AD) research suggest that alterations in microRNA (miRNA) expression are associated with disease pathology. Our previous studies suggest that A Disintegrin and Metalloproteinase 10 (ADAM10) expression is important in AD and could be modulated by an extended regulatory region that includes the 3' untranslated region. In this study, we have investigated the role of trans-acting factors in ADAM10 gene regulation. Our study shows that miRNA-140-5p has enhanced expression in the AD postmortem brain hippocampus using high-throughput miRNA arrays and quantitative real-time polymerase chain reaction. Interestingly, we have also seen that miRNA-140-5p seed sequence is present on 3' untranslated region of both ADAM10 and its transcription factor SOX2. The specific interaction of miRNA-140-5p with both ADAM10 and SOX2 signifies high regulatory importance of this miRNA in controlling ADAM10 expression. Thus, this investigation unravels mechanisms underlying ADAM10 downregulation by miR-140-5p and suggests that dysfunctional regulation of ADAM10 expression is exacerbated by AD-related neurotoxic effects. These findings underscore the importance of understanding the impact of trans-acting factors in the modulation of AD pathophysiology.

Erythrocyte membrane-encapsulated celecoxib improves the cognitive decline of Alzheimer's disease by concurrently inducing neurogenesis and reducing apoptosis in APP/PS1 transgenic mice

Alzheimer's disease (AD) is characterized by the loss of neurogenesis and excessive induction of apoptosis. The induction of neurogenesis and inhibition of apoptosis may be a promising therapeutic approach to combating the disease. Celecoxib (CB), a cyclooxygenase-2 specific inhibitor, could offer neuroprotection. Specifically, the CB-encapsulated erythrocyte membranes (CB-RBCMs) sustained the release of CB over a period of 72 h in vitro and exhibited high brain biodistribution efficiency following intranasal administration, which resulted in the clearance of aggregated β-amyloid proteins (Aβ) in neurons. The high accumulation of the CB-RBCMs in neurons resulted in a decrease in the neurotoxicity of CB and an increase in the migratory activity of neurons, and alleviated cognitive decline in APP/PS1 transgenic (Tg) mice. Indeed, COX-2 metabolic products including prostaglandin E2 (PGE₂) and PGD₂, PGE₂ induced neurogenesis by enhancing the expression of SOD2 and 14-3-3ζ, and PGD₂ stimulated apoptosis by increasing the expression of BIK and decreasing the expression of ARRB1. To this end, the CB-RBCMs achieved better effects on concurrently increasing neurogenesis and decreasing apoptosis than the phospholipid membrane-encapsulated CB liposomes (CB-PSPD-LPs), which are critical for the development and progression of AD. Therefore, CB-RBCMs provide a rational design to treat AD by promoting the self-repairing capacity of the brain.

Tribbles Pseudokinase 3 Induces Both Apoptosis and Autophagy in Amyloid-β-induced Neuronal Death

Amyloid-β (Aβ)-induced neuron death is considered central to the pathogenesis of Alzheimer's disease (AD). Among several death modalities, autophagy and apoptosis play important roles in Aβ-induced neuron death suggesting that there may be regulatory mechanisms that initiate both cell death pathways. However, molecules that govern both pathways have not been identified. Here, we report that, upon Aβ treatment, tribbles pseudokinase 3 (Trib3, an ortholog of Drosophila Tribbles) is up-regulated in neurons both in vivo and in vitro Increased Trib3 levels inhibited the activity of the kinase Akt by interacting with it. As a result, forkhead box O1 (FoxO1), a transcription factor that is negatively regulated by Akt, was activated, translocated to the nucleus, and induced the pro-apoptotic gene BCL2-like 11 (Bim). Conversely, FoxO1 responded to Aβ insult by binding to the Trib3 gene promoter, enhancing its expression. Our investigations further revealed that Trib3 also induces autophagy. We found that Trib3 indirectly activates unc-51-like autophagy-activating kinase1 (Ulk1) by impeding phosphorylation of, and thus inactivating, a negative regulator of Ulk1, mechanistic target of rapamycin. Ulk1 activation augmented autophagosome formation and reduced autophagy flux. Thus, Trib3 was required for formation of autophagosomes, which accumulated in neurons as autophagic flux was thwarted. Most importantly, silencing endogenous Trib3 strongly protected neurons from Aβ insult. Our results suggest that a self-amplifying feed-forward loop among Trib3, Akt, and FoxO1 in Aβ-treated neurons induces both apoptosis and autophagy, culminating in neuron death. Thus, Trib3 may serve as a potential therapeutic target for AD.

Yi-Zhi-Fang-Dai Formula Protects against Aβ1-42 Oligomer Induced Cell Damage via Increasing Hsp70 and Grp78 Expression in SH-SY5Y Cells

Yi-Zhi-Fang-Dai formula (YZFDF) is an experiential prescription used to cure dementia cases like Alzheimer's disease (AD). In this study, the main effective compounds of YZFDF have been identified from this formula, and the neuroprotective effect against Aβ_1–42 oligomer of YZFDF has been tested in SH-SY5Y cells. Our results showed that YZFDF could increase cell viability and could attenuate endothelial reticula- (ER-) mediated apoptosis. Evidence indicated that protein folding and endothelial reticula stress (ERS) played an important role in the AD pathological mechanism. We further explored the expression of Hsp70, an important molecular chaperon facilitating the folding of other proteins, and Grp78, the marker protein of ERS in SH-SY5Y cells. Data told us that YZFDF pretreatment could influence the mRNA and protein expression of these two proteins. At last, we also found that YZFDF pretreatment could activate Akt in SH-SY5Y cells. All these above indicate that YZFDF could be a potent therapeutic candidate for AD treatment.

In vitro antiaggregation and deaggregation potential of Rhizophora mucronata and its bioactive compound (+)- catechin against Alzheimer's beta amyloid peptide (25-35)

OBJECTIVE

Amyloid hypothesis states that endogenous β-amyloid peptides (Aβ), especially its aggregated oligomers and fibrils are the key pathogenic factors leading to Alzheimer's disease (AD). Therefore, inhibition of Aβ fibrillation rather than blocking its production is considered promising therapeutic intervention. Hence, the present study was carried out to assess the effect of methanolic leaf extract of R. mucronata (MERM) and its bioactive compound catechin on in vitro fibrillation of Aβ (25-35).

METHODOLOGY

Antiaggregation and disaggregation effect by MERM and (+)- catechin against Aβ (25-35) were assessed in three different phases by thioflavin T (ThT) fluorescence assay and confocal microscopic analysis. The conformational changes in the aggregated Aβ fibrils in the presence and absence of MERM and catechin were analysed by Fourier transform infrared (FTIR), transmission electron microscopy (TEM) and CD spectroscopy.

RESULTS

Results of ThT and confocal microscopic studies showed decrease in fluorescence intensity in MERM and catechin-treated groups illustrating that both MERM and catechin effectively inhibited fibril aggregation as well as destabilized preformed Aβ fibril. TEM revealed that MERM incubated samples were virtually devoid of structured fibrils but had an amorphous-like consistency, whereas the control contained structured fibrils of various width and length. FTIR analysis showed decrease in absorbance at 1630 cm^-1 (amide I region) in MERM-treated groups substantiating the results of ThT assay. Circular dichroism data indicate that catechin prevents the formation of β-structured aggregates of Aβ peptide.

CONCLUSION

Results suggest that MERM and catechin might have direct interaction with Aβ peptide preventing its fibrillation.

Prophylactic immunotherapy of Alzheimer's disease using recombinant amyloid-β B-cell epitope chimeric protein as subunit vaccine

Alzheimer's disease (AD) is a neurodegenerative disorder that impairs memory and cognition. The neuropathological features of the disease include senile plaques (SPs), neurofibrillary tangles (NFTs) and neuronal loss in affected brain regions. The amyloid cascade hypothesis suggests that production and accumulation of excessive amyloid-β (Aβ) may be the main cause in the onset and progression of Alzheimer's disease. Active and passive immunotherapy targeting Aβ may be the most promising strategy to prevent or treat AD. This commentary focuses on the prophylactic immunotherapy of Alzheimer's disease using recombinant Aβ B-cell epitope chimeric protein as subunit vaccine targeting amyloid-β. We discuss the efficiency and perspective of this type of recombinant subunit protein vaccine and suggest a novel direction on the path to a successful AD immunotherapy. This novel chimeric protein immunogen as subunit vaccine of AD may be designed to mimic the assembly states of Aβ42 or oligomers using multivalent foldable Aβ1-15 (B cell epitopes of Aβ42) and foreign T helper (Th) epitopes (as the T cell epitopes of Aβ42) constructs.

A novel recombinant 6Aβ15-THc-C chimeric vaccine (rCV02) mitigates Alzheimer's disease-like pathology, cognitive decline and synaptic loss in aged 3 × Tg-AD mice

Alzheimer's disease (AD) is a neurodegenerative disorder that impairs memory and cognition. Targeting amyloid-β (Aβ) may be currently the most promising immunotherapeutic strategy for AD. In this study, a recombinant chimeric 6Aβ15-THc-C immunogen was formulated with alum adjuvant as a novel Aβ B-cell epitope candidate vaccine (rCV02) for AD. We examined its efficacy in preventing the cognitive deficit and synaptic impairment in 3 × Tg-AD mice. Using a toxin-derived carrier protein, the rCV02 vaccine elicited robust Aβ-specific antibodies that markedly reduced AD-like pathology and improved behavioral performance in 3 × Tg-AD mice. Along with the behavioral improvement in aged 3 × Tg-AD mice, rCV02 significantly decreased calpain activation concurrent with reduced soluble Aβ or oligomeric forms of Aβ, probably by preventing dynamin 1 and PSD-95 degradation. Our data support the hypothesis that reducing Aβ levels in rCV02-immunized AD mice increases the levels of presynaptic dynamin 1 and postsynaptic PSD-95 allowing functional recovery of cognition. In conclusion, this novel and highly immunogenic rCV02 shows promise as a new candidate prophylactic vaccine for AD and may be useful for generating rapid and strong Aβ-specific antibodies in AD patients with pre-existing memory Th cells generated after immunization with conventional tetanus toxoid vaccine.

Estimation from moments measurements for amyloid depolymerisation

Estimating reaction rates and size distributions of protein polymers is an important step for understanding the mechanisms of protein misfolding and aggregation, a key feature for amyloid diseases. This study aims at setting this framework problem when the experimental measurements consist in the time-dynamics of a moment of the population (i.e. for instance the total polymerised mass, as in Thioflavin T measurements, or the second moment measured by Static Light Scattering). We propose a general methodology, and we solve the problem theoretically and numerically in the case of a depolymerising system. We then apply our method to experimental data of depolymerising oligomers, and conclude that smaller aggregates of ovPrP protein should be more stable than larger ones. This has an important biological implication, since it is commonly admitted that small oligomers constitute the most cytotoxic species during prion misfolding process.

A Novel Aβ B-Cell Epitope Vaccine (rCV01) for Alzheimer's Disease Improved Synaptic and Cognitive Functions in 3 × Tg-AD Mice

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive amyloid-β accumulation, loss of cognitive abilities, and synaptic alterations. Given the remarkable recovery of cognition in AD models of targeting-Aβ immunotherapy, we sought to determine the molecular correlate(s) associated with improvement. We evaluated the efficacy of a recombinant chimeric 6Aβ15-T antigen formulated with alum adjuvant as a novel Aβ B-cell epitope vaccine (rCV01) in 3 × Tg-AD mice. rCV01 elicited robust Th2-polarized Aβ-specific antibodies without autoimmune T cell responses in 3 × Tg-AD mice. The long-lasting anti-Aβ42 antibodies were associated with markedly reduced AD-like pathology, enhanced synaptic function, and improved cognitive performance in aged 3 × Tg-AD mice. This is the first report to provide one hypothesis for the improved outcomes following vaccination is a reduction in the levels of active calpain in rCV01-immunized AD mice, which is likely attributable to preventing dynamin 1 and PSD-95 degradation allowing functional recovery of cognition. rCV01 is a highly immunogenic recombinant chimeric 6Aβ15-T vaccine that shows clear neuroprotective properties in preclinical mouse models of AD and is a candidate for an effective AD vaccine.

Amyloid status imputed from a multimodal classifier including structural MRI distinguishes progressors from nonprogressors in a mild Alzheimer's disease clinical trial cohort

INTRODUCTION

Mild-Alzheimer's disease (AD) subjects without significant Aβ pathology represent a confounding finding for clinical trials because they may not progress clinically on the expected trajectory, adding variance into analyses where slowing of progression is being measured.

METHODS

A prediction model based on structural magnetic resonance imaging (MRI) in combination with baseline demographics and clinical measurements was used to impute Aβ status of a placebo-treated mild-AD sub-cohort (N = 385) of patients participating in global phase 3 trials. The clinical trajectories of this cohort were evaluated over 18 months duration of the trial, stratified by imputed Aβ status within a mixed-model repeated measures statistical framework.

RESULTS

In the imputed Aβ-positive cohort, both cognitive (ADAS-Cog14 and MMSE) and functional (ADCS-iADL) measures declined more rapidly than in the undifferentiated population.

DISCUSSION

Our results demonstrate imputing Aβ status from MRI scans in mild-AD subjects may be a useful screening tool in global clinical trials if amyloid measurement is not available.