Alzheimer's Disease: Past, Present, and Future

Characterization of Alzheimer's Disease-Associated Excitatory Neurons via Single-Cell RNA Sequencing Analysis

The detailed characteristics of neuronal cell populations in Alzheimer’s disease (AD) using single-cell RNA sequencing have not been fully elucidated. To explore the characterization of neuronal cell populations in AD, this study utilized the publicly available single-nucleus RNA-sequencing datasets in the transgenic model of 5X familial Alzheimer’s disease (5XFAD) and wild-type mice to reveal an AD-associated excitatory neuron population (C3:Ex.Neuron). The relative abundance of C3:Ex.Neuron increased at 1.5 months and peaked at 4.7 months in AD mice. Functional pathways analyses showed that the pathways positively related to neurodegenerative disease progression were downregulated in the C3:Ex.Neuron at 1.5 months in AD mice. Based on the differentially expressed genes among the C3:Ex.Neuron, four subtypes (C3.1–4) were identified, which exhibited distinct abundance regulatory patterns during the development of AD. Among these subtypes, the C3.1 neurons [marked by netrin G1 (Ntng1)] exhibited a similar regulatory pattern as the C3:Ex.Neuron in abundance during the development of AD. In addition, our gene set variation analysis (GSEA) showed that the C3.1 neurons, instead of other subtypes of the C3:Ex.Neuron, possessed downregulated AD pathways at an early stage (1.5 months) of AD mice. Collectively, our results identified a previously unidentified subset of excitatory neurons and provide a potential application of these neurons to modulate the disease susceptibility.

The Emerging Scenario of the Gut-Brain Axis: The Therapeutic Actions of the New Actor Kefir against Neurodegenerative Diseases

The fact that millions of people worldwide suffer from Alzheimer’s disease (AD) or Parkinson’s disease (PD), the two most prevalent neurodegenerative diseases (NDs), has been a permanent challenge to science. New tools were developed over the past two decades and were immediately incorporated into routines in many laboratories, but the most valuable scientific contribution was the “waking up” of the gut microbiota. Disturbances in the gut microbiota, such as an imbalance in the beneficial/pathogenic effects and a decrease in diversity, can result in the passage of undesired chemicals and cells to the systemic circulation. Recently, the potential effect of probiotics on restoring/preserving the microbiota was also evaluated regarding important metabolite and vitamin production, pathogen exclusion, immune system maturation, and intestinal mucosal barrier integrity. Therefore, the focus of the present review is to discuss the available data and conclude what has been accomplished over the past two decades. This perspective fosters program development of the next steps that are necessary to obtain confirmation through clinical trials on the magnitude of the effects of kefir in large samples.

The effect and underlying mechanisms of garlic extract against cognitive impairment and Alzheimer's disease: A systematic review and meta-analysis of experimental animal studies

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) is the main cause of dementia, and according to traditional Chinese medicine (TCM), it is leaded by the deficiency of essence, qi, and blood. Allii sativi bulbus, acrid and warm, is traditionally used as the important adjuvant and conductant drug to distribute essence-qi throughout the body, fortify the spleen and harmonize the stomach. Garlic (Allium sativum L., Alliaceae) has also been reported to display potential anti-AD effect both in vitro and in vivo studies, while no systematic review of these studies has been conducted.

AIM OF THE STUDY

This review aims to provide a comprehensive evaluation of the effect and underlying mechanism of garlic extract against cognitive impairment and AD neuropathology through meta-analysis and sensitivity analysis.

MATERIALS AND METHODS

Eligible studies were searched from PubMed, Web of Science and EMBASE from February to March in 2020, and 13 studies describing the effect of garlic extract in AD animal models (551 mice and 88 rats) were identified.

RESULTS

Analysis of these studies showed that garlic extract could reduce cerebral Aβ levels [Aβ₄₀: SMD -8.62(-11.75, -5.49), p < 0.00001 and Aβ₄₂: SMD -11.70(-18.01, -5.39), p=0.0003], and increase the number of right crossings in MWM [SMD 2.87(1.48, 4.26), p < 0.0001] in AD animals. However, moderate risk of bias (quality score ranged from 40% to 60%) is revealed by SYRCLE's checklist, mainly because of the lacks of sample size calculation, random allocation and blind assessment.

CONCLUSIONS

This review shows that garlic extract may be effective in alleviating cognitive impairment and neuropathology in AD animal models. High quality AD animal studies with enough sample size and more comprehensive evaluation of outcomes are needed to further confirm the results.

The largest isoform of Ankyrin-G is required for lattice structure of the axon initial segment

Alzheimer's disease (AD) is the most frequent neurodegenerative disease and a common dementia in elderly individuals. Previous studies found a strong correlation between axon initial segment (AIS) defects and AD, but it remains unclear whether AD itself changes the arrangement of AIS components, and the mechanisms by which adaptor proteins and ion channels in the AIS are disturbed in AD are not well understood. With super-resolution structured illumination microscopy (SIM) revealing axonal structures, here we imaged the lattice structure of completely assembled AIS in APP/PS1 neurons. By analyzing the images with Gaussian fitting and 1D mean autocorrelation, we found dual spacings (∼200 nm and ∼370 nm) of Ankyrin-G (AnkG), Na_v1.2 and βIV-spectrin in AD model APP/PS1 mice due to the low-expressed 480-kDa AnkG. To identify the roles of each AnkG isoform, two isoforms were separately expressed in neurons from AnkG conditional knockout mice. Mice rescued with 270-kDa AnkG displayed dual spacings of AnkG components in cultured neurons and impaired in spatial memory, while transgenic mice expressing 480-kDa AnkG showed a normal molecular distribution in the AIS and normal cognitive performance. Our findings provide new insight into the mechanisms underlying impaired cognition associated with neurodegenerative diseases such as AD.

Nanoparticle-Guided Brain Drug Delivery: Expanding the Therapeutic Approach to Neurodegenerative Diseases

Neurodegenerative diseases (NDs) represent a heterogeneous group of aging-related disorders featured by progressive impairment of motor and/or cognitive functions, often accompanied by psychiatric disorders. NDs are denoted as 'protein misfolding' diseases or proteinopathies, and are classified according to their known genetic mechanisms and/or the main protein involved in disease onset and progression. Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD) are included under this nosographic umbrella, sharing histopathologically salient features, including deposition of insoluble proteins, activation of glial cells, loss of neuronal cells and synaptic connectivity. To date, there are no effective cures or disease-modifying therapies for these NDs. Several compounds have not shown efficacy in clinical trials, since they generally fail to cross the blood-brain barrier (BBB), a tightly packed layer of endothelial cells that greatly limits the brain internalization of endogenous substances. By engineering materials of a size usually within 1-100 nm, nanotechnology offers an alternative approach for promising and innovative therapeutic solutions in NDs. Nanoparticles can cross the BBB and release active molecules at target sites in the brain, minimizing side effects. This review focuses on the state-of-the-art of nanoengineered delivery systems for brain targeting in the treatment of AD, PD and HD.

Alzheimer's Disease-Related Metabolic Pattern in Diverse Forms of Neurodegenerative Diseases

Dementia is broadly characterized by cognitive and psychological dysfunction that significantly impairs daily functioning. Dementia has many causes including Alzheimer’s disease (AD), dementia with Lewy bodies (DLB), and frontotemporal lobar degeneration (FTLD). Detection and differential diagnosis in the early stages of dementia remains challenging. Fueled by AD Neuroimaging Initiatives (ADNI) (Data used in preparation of this article were obtained from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. As such, the investigators within ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report.), a number of neuroimaging biomarkers for AD have been proposed, yet it remains to be seen whether these markers are also sensitive to other types of dementia. We assessed AD-related metabolic patterns in 27 patients with diverse forms of dementia (five had probable/possible AD while others had atypical cases) and 20 non-demented individuals. All participants had positron emission tomography (PET) scans on file. We used a pre-trained machine learning-based AD designation (MAD) framework to investigate the AD-related metabolic pattern among the participants under study. The MAD algorithm showed a sensitivity of 0.67 and specificity of 0.90 for distinguishing dementia patients from non-dementia participants. A total of 18/27 dementia patients and 2/20 non-dementia patients were identified as having AD-like patterns of metabolism. These results highlight that many underlying causes of dementia have similar hypometabolic pattern as AD and this similarity is an interesting avenue for future research.

Misregulation of Wnt Signaling Pathways at the Plasma Membrane in Brain and Metabolic Diseases

Wnt signaling pathways constitute a group of signal transduction pathways that direct many physiological processes, such as development, growth, and differentiation. Dysregulation of these pathways is thus associated with many pathological processes, including neurodegenerative diseases, metabolic disorders, and cancer. At the same time, alterations are observed in plasma membrane compositions, lipid organizations, and ordered membrane domains in brain and metabolic diseases that are associated with Wnt signaling pathway activation. Here, we discuss the relationships between plasma membrane components-specifically ligands, (co) receptors, and extracellular or membrane-associated modulators-to activate Wnt pathways in several brain and metabolic diseases. Thus, the Wnt-receptor complex can be targeted based on the composition and organization of the plasma membrane, in order to develop effective targeted therapy drugs.

Rethinking modeling Alzheimer's disease progression from a multi-task learning perspective with deep recurrent neural network

Alzheimer's disease (AD) is a severe neurodegenerative disorder that usually starts slowly and progressively worsens. Predicting the progression of Alzheimer's disease with longitudinal analysis on the time series data has recently received increasing attention. However, training an accurate progression model for brain network faces two major challenges: missing features, and the small sample size during the follow-up study. According to our analysis on the AD progression task, we thoroughly analyze the correlation among the multiple predictive tasks of AD progression at multiple time points. Thus, we propose a multi-task learning framework that can adaptively impute missing values and predict future progression over time from a subject's historical measurements. Progression is measured in terms of MRI volumetric measurements, trajectories of a cognitive score and clinical status. To this end, we propose a new perspective of predicting the AD progression with a multi-task learning paradigm. In our multi-task learning paradigm, we hypothesize that the inherent correlations exist among: (i). the prediction tasks of clinical diagnosis, cognition and ventricular volume at each time point; (ii). the tasks of imputation and prediction; and (iii). the prediction tasks at multiple future time points. According to our findings of the task correlation, we develop an end-to-end deep multi-task learning method to jointly improve the performance of assigning missing value and prediction. We design a balanced multi-task dynamic weight optimization. With in-depth analysis and empirical evidence on Alzheimer's Disease Neuroimaging Initiative (ADNI), we show the benefits and flexibility of the proposed multi-task learning model, especially for the prediction at the M60 time point. The proposed approach achieves 5.6%, 5.7%, 4.0% and 11.8% improvement with respect to mAUC, BCA and MAE (ADAS-Cog13 and Ventricles), respectively.

Neuroprotective Potential of Mung Bean (Vigna radiata L.) Polyphenols in Alzheimer's Disease: A Review

Mung bean contains various neuroprotective polyphenols, so it might be a healthy food for Alzheimer's disease (AD) prevention. Totally, 19 major phenolic compounds were quantified in mung bean, including 10 phenolic acids and 9 flavonoids. After summarizing their contents and effective doses in rodent AD models, it was speculated that vitexin, isovitexin, sinapic acid, and ferulic acid might be the major bioactive compounds for mung bean-mediated neuroprotection. The mechanisms involved inhibition of β-amyloidogenesis, tau hyperphosphorylation, oxidative stress, and neuroinflammation, and promotion of autophagy and acetylcholinesterase enzyme activity. Notably, the neuroprotective phenolic profile in mung bean changed after germination, with decreased vitexin and isovitexin, and increased rutin, isoquercitrin, isorhamnetin, and caffeic acid detected. However, only studies of individual phenolic compounds in mung bean are published at present. Hence, further studies are needed to elucidate the neuroprotective activities and mechanisms of extractions of mung bean seeds and sprouts, and the synergism between different phenolic compounds.

Amyloids as Building Blocks for Macroscopic Functional Materials: Designs, Applications and Challenges

Amyloids are self-assembled protein aggregates that take cross-β fibrillar morphology. Although some amyloid proteins are best known for their association with Alzheimer’s and Parkinson’s disease, many other amyloids are found across diverse organisms, from bacteria to humans, and they play vital functional roles. The rigidity, chemical stability, high aspect ratio, and sequence programmability of amyloid fibrils have made them attractive candidates for functional materials with applications in environmental sciences, material engineering, and translational medicines. This review focuses on recent advances in fabricating various types of macroscopic functional amyloid materials. We discuss different design strategies for the fabrication of amyloid hydrogels, high-strength materials, composite materials, responsive materials, extracellular matrix mimics, conductive materials, and catalytic materials.

Using stable isotope labeling to advance our understanding of Alzheimer's disease etiology and pathology

Stable isotope labeling with mass spectrometry (MS)-based proteomic analysis has become a powerful strategy to assess protein steady-state levels, protein turnover, and protein localization. Applying these analyses platforms to neurodegenerative disorders may uncover new aspects of the etiology of these devastating diseases. Recently, stable isotopes-MS has been used to investigate early pathological mechanisms of Alzheimer's disease (AD) with mouse models of AD-like pathology. In this review, we summarize these stable isotope-MS experimental designs and the recent application in the context of AD pathology. We also describe our current efforts aimed at using nuclear magnetic resonance (NMR) analysis of stable isotope-labeled amyloid fibrils from AD mouse model brains. Collectively, these methodologies offer new opportunities to study proteome changes in AD and other neurodegenerative diseases by elucidating mechanisms to target for treatment and prevention.

MicroRNA-132-3p alleviates neuron apoptosis and impairments of learning and memory abilities in Alzheimer's disease by downregulation of HNRNPU stabilized BACE1

Alzheimer's disease (AD) is a progressive neuro-degenerative disease characterized by dementia. MicroRNAs (miRNAs) are involved in many diseases, including AD. MiR-132-3p has been identified to be downregulated in AD. In this study, we explored the effects of miR-132-3p on neuron apoptosis and impairments of learning and memory abilities. Aβ1-42-stimulated SH-SY5Y cells were used as in vitro models of AD. An AD-like homocysteine (Hcy) rat model was established to evaluate the effects of miR-132-3p on AD pathogenesis in vivo. RIP, RNA pull down and luciferase reporter assays were conducted to investigate the relationship between miR-132-3p and its downstream target genes. The viability and apoptosis of SH-SY5Y cells were measured by CCK-8 and TUNEL assays. The rat spatial learning and memory abilities were accessed using Morris water maze test. Results indicated that miR-132-3p was downregulated in SH-SY5Y cells after Aβ1-42 treatment and promoted cell apoptosis. Mechanistically, miR-132-3p targeted heterogeneous nuclear ribonucleoprotein U (HNRNPU). HNRNPU acted as an RNA binding protein (RBP) to regulate the mRNA stability of β-site amyloid precursor protein cleaving enzyme 1 (BACE1). Overexpression of HNRNPU or BACE1 reversed the effects of miR-132-3p overexpression on the viability and apoptosis of Aβ1-42-treated SH-SY5Y cells. In vivo experiments revealed the downregulation of miR-132-3p in the hippocampus of Hcy-treated rats. MiR-132-3p suppressed levels of apoptotic genes in hippocampus and reduced impairments of learning and memory abilities in Hcy-treated rats. In conclusion, miR-132-3p reduces apoptosis of SH-SY5Y cells and alleviates impairments of learning and memory abilities in AD rats by modulating the HNRNPU/BACE1 axis.

Blood Triglyceride and High-Density Lipoprotein Levels Are Associated with Plasma Amyloid-β Transport: A Population-Based Cross-Sectional Study

BACKGROUND

Studies have found that blood lipids are associated with plasma amyloid-β (Aβ) levels, but the underlying mechanism is still unclear. Two Aβ transporters, soluble form of low-density lipoprotein receptor related protein-1 (sLRP1) and soluble receptor of advanced glycation end products (sRAGE), are crucial in peripheral Aβ transport.

OBJECTIVE

The aim was to investigate the effects of lipids on the relationships between plasma Aβ and transporter levels.

METHODS

This study included 1,436 adults aged 40 to 88 years old. Blood Aβ, sLRP1, sRAGE, and lipid levels were measured. Univariate and multivariate analyses were used to analyze the relationships between lipids and plasma Aβ, sLRP1, and sRAGE.

RESULTS

After adjusting for all possible covariates, high-density lipoprotein (HDL-c) was positively associated with plasma Aβ42 and sRAGE (β= 6.158, p = 0.049; β= 121.156, p < 0.001, respectively), while triglyceride (TG) was negatively associated with plasma Aβ40, Aβ42, and sRAGE (β= -48.389, p = 0.017; β= -11.142, p = 0.020; β= -147.937, p = 0.003, respectively). Additionally, positive correlations were found between plasma Aβ and sRAGE in the normal TG (Aβ40: β= 0.034, p = 0.005; Aβ42: β= 0.010, p = 0.001) and HDL-c groups (Aβ40: β= 0.023, p = 0.033; Aβ42: β= 0.008, p = 0.002) but not in the high TG and low HDL-c groups.

CONCLUSION

Abnormal levels of TG and HDL-c are associated with decreased Aβ and sRAGE levels. Positive correlations between plasma Aβ and sRAGE were only found in the normal TG and HDL-c groups but not in the high TG and low HDL-c groups. These results indicated that dyslipidemia contributing to plasma Aβ levels might also be involved in peripheral Aβ clearance.

Design, synthesis, and bio-evaluation of new isoindoline-1,3-dione derivatives as possible inhibitors of acetylcholinesterase

Background and purpose:

Alzheimer’s disease is considered one of the lead causes of elderly death around the world. A significant decrease in acetylcholine level in the brain is common in most patients with Alzheimer’s disease, therefore acetylcholinesterase (AChE) inhibitors such as donepezil and rivastigmine are widely used for patients with limited therapeutic results and major side effects.

Experimental approach:

A series of isoindoline-1,3-dione -N-benzyl pyridinium hybrids were designed, synthesized and evaluated as anti-Alzheimer agents with cholinesterase inhibitory activities. The structure of the compounds were confirmed by various methods of analysis such as HNMR, CNMR, and FT-IR. Molecular modeling studies were also performed to identify the possible interactions between neprilysin and synthesized compounds.

Findings/Results:

The biological screening results indicated that all synthesized compounds displayed potent inhibitory activity with IC₅₀ values ranging from 2.1 to 7.4 μM. Among synthesized compounds, para-fluoro substituted compounds 7a and 7f exhibited the highest inhibitory potency against AChE (IC₅₀ = 2.1 μM). Molecular modeling studies indicated that the most potent compounds were able to interact with both catalytic and peripheral active sites of the enzyme. Also, some of the most potent compounds (7a, 7c, and 7f) demonstrated a neuroprotective effect against H₂O₂-induced cell death in PC12 neurons.

Conclusion and implications:

The synthesized compounds demonstrated moderate to good AChE inhibitory effect with results higher than rivastigmine.

The Economic Burden of Alzheimer's Disease in Zhejiang Province

BACKGROUND

The World Alzheimer Report has described and predicted the economic burden of Alzheimer's disease (AD) patients in detail for four consecutive years. There was a large-scale national survey in China launched by Professor Jianping Jia in 2015, but it did not adequately represent the average economic burden of AD patients in Zhejiang Province.

OBJECTIVE

To investigate the economic burden and main factors influencing Alzheimer's disease (AD) in Zhejiang Province.

METHODS

We recruited 830 patients from 10 cities in Zhejiang Province, evaluated their per capita and total cost related to AD treatment and care in 2017, and analyzed the main factors affecting economic burden from the perspective of demographic characteristics and disease severity.

RESULTS

In 2017, per capita cost of AD was 114,343.7 yuan, while the total cost was 27.53 billion yuan, accounting for 0.77% of Zhejiang Province's GDP (5176.8 billion yuan). Total cost, direct medical cost, and indirect cost have different correlations with age, education level, type of work, marital status, comorbidity, and disease severity.

CONCLUSION

The economic burden of AD in Zhejiang Province is heavy, similar to the national burden, and interventions based on demographic characteristics and disease severity can help reduce it.

Living with the enemy: from protein-misfolding pathologies we know, to those we want to know

Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.

The emerging possibility of the use of geniposide in the treatment of cerebral diseases: a review

With the advanced discoveries in the field of pathogenesis, a series of cerebral diseases, such as cerebral ischaemia, Alzheimer's disease, and depression, have been found to have multiple signalling targets in the microenvironment. Only a few existing agents have been shown to have curative effects due to this specific circumstance. In recent decades, active ingredients isolated from natural plants have been shown to be crucial for original drug development. Geniposide, mainly extracted from Gardenia jasminoides Ellis, is representative of these natural products. Geniposide demonstrates various biological activities in the treatment of cerebral, cardiovascular, hepatic, tumorous, and other diseases. The multiple protective effects of geniposide on the brain have especially drawn increasing attention. Thus, this article specifically reviews the characteristics of current models of cerebral ischaemia and illustrates the possible effects of geniposide and its pathogenetic mechanisms on these models. Geniposide has been shown to significantly reduce the area of cerebral infarction and alleviate neuronal damage and necrosis mainly by inhibiting inflammatory signals, including NLRP3, TNF-α, IL-6, and IL-1β. Neuronal protection was also involved in activating the PI3K/Akt and Wnt/catenin pathways. Geniposide was able to increase autophagy and inhibit apoptosis by regulating the function of mTOR in treating Alzheimer's disease. Geniposide has also been shown to act as a glucagon-like peptide-1 receptor (GLP-1R) agonist to reduce amyloid plaques and inhibit oxidative stress to alleviate memory impairment as well as synaptic loss. Moreover, geniposide has been shown to exert antidepressant effects primarily by regulating the hypothalamic-pituitary-adrenal (HPA) axis. Detailed explorations have shown that the biological activities of inhibiting inflammatory cytokine secretion, alleviating oxidative stress, and suppressing mitochondrial damage are also involved in the mechanism of action of geniposide. Therefore, geniposide is a promising agent awaiting further exploration for the treatment of cerebral diseases via various phenotypes or signalling pathways.

Novel Tracers and Radionuclides in PET Imaging

The use of PET imaging agents in oncology, cardiovascular disease, and neurodegenerative disease shows the power of this technique in evaluating the molecular and biological characteristics of numerous diseases. These agents provide crucial information for designing therapeutic strategies for individual patients. Novel PET tracers are in continual development and many have potential use in clinical and research settings. This article discusses the potential applications of tracers in diagnostics, the biological characteristics of diseases, the ability to provide prognostic indicators, and using this information to guide treatment strategies including monitoring treatment efficacy in real time to improve outcomes and survival.

Curcumin Alleviates Aβ42-Induced Neuronal Metabolic Dysfunction via the Thrb/SIRT3 Axis and Improves Cognition in APPTG Mice

Curcumin has been reported to have a therapeutic effect on Alzheimer's disease (AD), but the specific mechanism remains to be elucidated. In the present research, we aimed to investigate the effect and molecular mechanism of curcumin on AD. Mouse primary hippocampal neuron cells were treated with various concentrations of beta-amyloid 42 (Aβ₄₂) and the results found that Aβ₄₂ inhibited cell viability in a dose-dependent manner. Compared with 50 ng/mL Aβ₄₂, 500 ng/mL Aβ₄₂ could further promote cell apoptosis, reduce the ratio of Nicotinamide adenine dinucleotide (NAD(+))/Nicotinamide adenine diphosphate hydride (NADH) and Adenosine 5'-triphosphate (ATP) level, and inhibit Sirtuins 3 (SIRT3) deacetylation activity and protein expression of Thyroid hormone receptor beta (Thrb) and SIRT3. Hence, 500 ng/mL Aβ₄₂ was used to establish a cell model of AD. Curcumin significantly reversed the inhibitory effects of Aβ₄₂ on cell viability, SIRT3 deacetylation activity, the ratio of NAD⁺/NADH, ATP level and the protein expression of Thrb and SIRT3, and the promotive effect on apoptosis. ChIPBase was used to predict the binding region of Thrb and SIRT3. Dual luciferase reporter gene and Chromatin immune precipitation (ChIP) assays were employed to verify the relationship between Thrb and promoter of SIRT3 mRNA. Overexpression of Thrb recovered Aβ₄₂ induced metabolic dysfunction, while Thrb silence aggravated Aβ₄₂ induced metabolic dysfunction. Moreover, Thrb silence or 3-TYP (a selective inhibitor of SIRT3) treatment abolished the amelioration of curcumin on Aβ₄₂ induced metabolic dysfunction. Additionally, curcumin attenuated memory deficits in Amyloid precursor protein transgenic (APP_TG) mice. Collectively, curcumin alleviated Aβ₄₂-induced neuronal metabolic dysfunction through increasing Thrb expression and SIRT3 activity and improved cognition in APP_TG mice.

Alzheimer's disease neuropathology is exacerbated following traumatic brain injury. Neuroprotection by co-administration of nanowired mesenchymal stem cells and cerebrolysin with monoclonal antibodies to amyloid beta peptide

Military personnel are prone to traumatic brain injury (TBI) that is one of the risk factors in developing Alzheimer's disease (AD) at a later stage. TBI induces breakdown of the blood-brain barrier (BBB) to serum proteins into the brain and leads to extravasation of plasma amyloid beta peptide (ΑβP) into the brain fluid compartments causing AD brain pathology. Thus, there is a need to expand our knowledge on the role of TBI in AD. In addition, exploration of the novel roles of nanomedicine in AD and TBI for neuroprotection is the need of the hour. Since stem cells and neurotrophic factors play important roles in TBI and in AD, it is likely that nanodelivery of these agents exert superior neuroprotection in TBI induced exacerbation of AD brain pathology. In this review, these aspects are examined in details based on our own investigations in the light of current scientific literature in the field. Our observations show that TBI exacerbates AD brain pathology and TiO₂ nanowired delivery of mesenchymal stem cells together with cerebrolysin-a balanced composition of several neurotrophic factors and active peptide fragments, and monoclonal antibodies to amyloid beta protein thwarted the development of neuropathology following TBI in AD, not reported earlier.

1,5-Benzoxazepines as a unique and potent scaffold for activity drugs: A review

Benzoxazepines constitute a huge number of organic compounds widely described in the literature. Many of them are distinguished by their biological properties. Among them, our attention was drawn to 1,5-benzoxazepine derivatives due to their interesting pharmacological properties. As is reported in the literature, these compounds are not only good building blocks in organic synthesis but also have interesting biological and pharmacological properties. This article is the first review publication to describe the synthesis methods and unique properties of 1,5-benzoxazepines. Literature reports widely describe the biological properties of 1,5-benzoxazepine, like anticancer, antibacterial, or antifungal activities. 1,5-Benzoxazepine derivatives can also interact with G-protein-coupled receptors and could be incorporated into new potential drugs, among others, in treating neuronal disorders like Alzheimer's and Parkinson's disease.

Mitigation of oxidative stress with dihydroactinidiolide, a natural product against scopolamine-induced amnesia in Swiss albino mice

The present work describes the neuroprotective efficacy of DHAc under escalated oxidative stress condition in scopolamine-induced amnesic mice. During the toxicity test of DHAc in mice, the acute dose (LD₅₀) is found to be 3.468 mg/kg bw and the sub-acute dose is 0.68 mg/kg bw. Improved cognitive and learning abilities are observed in Morris water maze and Y-maze test in 10 days DHAc (0.68 mg/kg bw) treated scopolamine-induced male Swiss albino mice. In the molecular level these changes are monitored as reduced oxidative load followed by significantly lower lipid peroxidation and protein carbonylation, increased superoxide dismutase, catalase, acetylcholinesterase, caspase-3 activity and glutathione content followed by higher expression of anti apoptotic protein bcl-2 in mice brain as compared to scopolamine (1 mg/kg bw) treated mice. Meanwhile real time PCR shows higher expression of brain derived neurotrophic factor (BDNF) and synaptophysin in DHAc pretreated scopolamine treated mice brain. HPLC analysis suggested its possible blood brain barrier crossing ability. Overall DHAc reversed behavioral anomalies in the scopolamine treated mice via oxidative stress quenching, enhancing antioxidative enzyme activity, enhancing BDNF and synaptophysin mRNA levels and reducing expression of apoptotic protein Bax.

Association of Dietary Habits with Mild Cognitive Impairment among Elderly in Rural Area of North China

BACKGROUND

Recent findings suggest a possible role of diet, particularly nutrient intakes and dietary patterns, in the prevalence of mild cognitive impairment (MCI); few studies, however, have been explicitly devoted to the relationship between dietary habits and MCI.

OBJECTIVES

We aimed to explore the association between dietary habits, including meal timing, and MCI among older Chinese adults.

METHODS

This cross-sectional study involved data collected at the baseline of the Tianjin Elderly Nutrition and Cognition Cohort (TENCC) study, in which 3,111 community-dwelling older adults (326 MCI patients and 2,785 non-MCIs) from a rural area of Tianjin, China, were recruited. In March 2018 to June 2019, all participants underwent a detailed neuropsychological evaluation that allowed for psychometric MCI classification. Information on self-reported dietary behaviors was gathered via face-to-face interviews. Crude and multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression models.

RESULTS

In the multivariable-adjusted models, eating breakfast 4 to 6 times per week (vs. ≤3 times per week, OR: 0.45; 95% CI: 0.26, 0.75), drinking water before breakfast (yes vs. no, OR: 0.64; 95% CI: 0.51, 0.82), consuming water ≥1.5L per day (vs. <1.5L per day, OR: 0.64; 95% CI: 0.51, 0.82), and having lunch after 12:00 (vs. before 12:00, OR: 0.59; 95% CI: 0.47, 0.75) were associated with decreased risk of MCI. Participants who consumed higher amounts of cooking oil were at a higher risk of MCI (moderate vs. low, OR: 1.42; 95% CI: 1.04, 1.92; high vs. low, OR: 1.40; 95% CI: 1.07-1.83).

CONCLUSION

This study suggests that dietary habits, including breakfast frequency, daily water consumption, cooking oil consumption, and meal timing, may be associated with the risk of MCI. If replicated, these findings would open new possibilities of dietary interventions for MCI.

Lighting and Alzheimer's Disease and Related Dementias: Spotlight on Sleep and Depression

Alzheimer's disease and related dementias is the collective term for a progressive neurodegenerative disease for which there is presently no cure. This paper focuses on two symptoms of the disease, sleep disturbances and depression, and discusses how light can be used as a non-pharmacological intervention to mitigate their negative effects. Bright days and dark nights are needed for health and well-being, but the present components of the built environment, especially those places where older adults spend most of their days, are too dimly illuminated during the day and too bright at night. To be effective light needs to be correctly specified, implemented, and measured. Yet without the appropriate specification and measurement of the stimulus, researchers will not be able to successfully demonstrate positive results in the field, nor will lighting designers and specifiers have the confidence to implement lighting solutions for promoting better sleep and mood in this population.

3D Models as an Adjunct for Models in Studying Alzheimer’s Disease

Alzheimer’s disease (AD) is one of the most common causes of dementia. Disease progression is marked by cognitive decline and memory impairment due to neurodegenerative processes in the brain stemming from amyloid-β (Aβ) deposition and formation of neurofibrillary tangles. Pathogenesis in AD is dependent on two main neurological processes: formation of intracellular neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau protein and deposition of extracellular senile Aβ peptides. Given the nature of the disease, the pathology and progression of AD in vivo in humans have been difficult to study in vivo. To this degree, models can help to study the disease pathogenesis, biochemistry, immunological functions, genetics, and potential pharmacotherapy. While animal and two-dimensional (2D) cell culture models have facilitated significant progress in studying the disease, more recent application of novel three-dimensional (3D) culture models has exhibited several advantages. Herein, we describe a brief background of AD, and how current animal, 2D, and 3D models facilitate the study of this disease and associated therapeutics.

Prediction of the progression from mild cognitive impairment to Alzheimer's disease using a radiomics-integrated model

Objective:

This study aimed to build and validate a radiomics-integrated model with whole-brain magnetic resonance imaging (MRI) to predict the progression of mild cognitive impairment (MCI) to Alzheimer’s disease (AD).

Methods:

357 patients with MCI were selected from the ADNI database, which is an open-source database for AD with multicentre cooperation, of which 154 progressed to AD during the 48-month follow-up period. Subjects were divided into a training and test group. For each patient, the baseline T₁WI MR images were automatically segmented into white matter, gray matter and cerebrospinal fluid (CSF), and radiomics features were extracted from each tissue. Based on the data from the training group, a radiomics signature was built using logistic regression after dimensionality reduction. The radiomics signatures, in combination with the apolipoprotein E4 (APOE4) and baseline neuropsychological scales, were used to build an integrated model using machine learning. The receiver operating characteristics (ROC) curve and data of the test group were used to evaluate the diagnostic accuracy and reliability of the model, respectively. In addition, the clinical prognostic efficacy of the model was evaluated based on the time of progression from MCI to AD.

Results:

Stepwise logistic regression analysis showed that the APOE4, clinical dementia rating, AD assessment scale, and radiomics signature were independent predictors of MCI progression to AD. The integrated model was constructed based on independent predictors using machine learning. The ROC curve showed that the accuracy of the model in the training and the test sets was 0.814 and 0.807, with a specificity of 0.671 and 0.738, and a sensitivity of 0.822 and 0.745, respectively. In addition, the model had the most significant diagnostic efficacy in predicting MCI progression to AD within 12 months, with an AUC of 0.814, sensitivity of 0.726, and specificity of 0.798.

Conclusion:

The integrated model based on whole-brain radiomics can accurately identify and predict the high-risk population of MCI patients who may progress to AD. Radiomics biomarkers are practical in the precursory stage of such disease.

Group 2 innate lymphoid cells are numerically and functionally deficient in the triple transgenic mouse model of Alzheimer's disease

Background

The immune pathways in Alzheimer’s disease (AD) remain incompletely understood. Our recent study indicates that tissue-resident group 2 innate lymphoid cells (ILC2) accumulate in the brain barriers of aged mice and that their activation alleviates aging-associated cognitive decline. The regulation and function of ILC2 in AD, however, remain unknown.

Methods

In this study, we examined the numbers and functional capability of ILC2 from the triple transgenic AD mice (3xTg-AD) and control wild-type mice. We investigated the effects of treatment with IL-5, a cytokine produced by ILC2, on the cognitive function of 3xTg-AD mice.

Results

We demonstrate that brain-associated ILC2 are numerically and functionally defective in the triple transgenic AD mouse model (3xTg-AD). The numbers of brain-associated ILC2 were greatly reduced in 7-month-old 3xTg-AD mice of both sexes, compared to those in age- and sex-matched control wild-type mice. The remaining ILC2 in 3xTg-AD mice failed to efficiently produce the type 2 cytokine IL-5 but gained the capability to express a number of proinflammatory genes. Administration of IL-5, a cytokine produced by ILC2, transiently improved spatial recognition and learning in 3xTg-AD mice.

Conclusion

Our results collectively indicate that numerical and functional deficiency of ILC2 might contribute to the cognitive impairment of 3xTg-AD mice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02202-2.

Recent Trends in the Management of Alzheimer's Disease: Current Therapeutic Options and Drug Repurposing Approaches

Alzheimer's disease is one of the most progressive forms of dementia, ultimately leading to death in aged populations. The major hallmarks of Alzheimer's disease include deposition of extracellular amyloid senile plaques and intracellular neurofibrillary tangles in brain neuronal cells. Although there are classical therapeutic options available for the treatment of the diseases, however, they provide only a symptomatic relief and do not modify the molecular pathophysiological course of the disease. Recent research advances in Alzheimer's disease have highlighted the potential role of anti-amyloid, anti-tau, and anti-inflammatory therapies. However, these therapies are still in different phases of pre-clinical/clinical development. In addition, drug repositioning/repurposing is another interesting and promising approach to explore rationalized options for the treatment of Alzheimer's disease. This review discusses the different aspects of the pathophysiological mechanism involved in the progression of Alzheimer's disease along with the limitations of current therapies. Furthermore, this review also highlights emerging investigational drugs along with recent drug repurposing approaches for Alzheimer's disease.

The Application of Convolutional Neural Network Model in Diagnosis and Nursing of MR Imaging in Alzheimer's Disease

The disease Alzheimer is an irrepressible neurologicalbrain disorder. Earlier detection and proper treatment of Alzheimer's disease can help for brain tissue damage prevention. The study was intended to explore the segmentation effects of convolutional neural network (CNN) model on Magnetic Resonance (MR) imaging for Alzheimer's diagnosis and nursing. Specifically, 18 Alzheimer's patients admitted to Indira Gandhi Medical College (IGMC) hospital were selected as the experimental group, with 18 healthy volunteers in the Ctrl group. Furthermore, the CNN model was applied to segment the MR imaging of Alzheimer's patients, and its segmentation effects were compared with those of the fully convolutional neural network (FCNN) and support vector machine (SVM) algorithms. It was found that the CNN model demonstrated higher segmentation precision, and the experimental group showed a higher clinical dementia rating (CDR) score and a lower mini-mental state examination (MMSE) score (P < 0.05). The size of parahippocompalgyrus and putamen was bigger in the Ctrl (P < 0.05). In experimental group, the amplitude of low-frequency fluctuation (ALFF) was positively correlated with the MMSE score in areas of bilateral cingulum gyri (r = 0.65) and precuneus (r = 0.59). In conclusion, the grey matter structure is damaged in Alzheimer's patients, and hippocampus ALFF and regional homogeneity (ReHo) is involved in the neuronal compensation mechanism of hippocampal damage, and the caregivers should take an active nursing method.

Insomnia Burden and Future Perspectives

Insomnia is an important but widely ignored health problem in modern society. Despite unequivocal evidence on its large prevalence, health and social impacts, comorbidities, and various pharmacologic and nonpharmacologic (behavioral and device-based) approaches, its effective management is still difficult and often incomplete. This article discusses the role of insomnia in modern societies, newer complicating factors, and its overall social and public health burden. Acute insomnia and sleep difficulties during pandemic and confinement are reviewed. The article also focuses on newer developments accumulating in the field of insomnia and possible future trends.

Effects of far infrared light on Alzheimer's disease-transgenic mice

Far infrared light has been used in many medical procedures. However, the detailed biological mechanisms of infrared light's effects have not yet been elucidated. Many researchers have pointed out the thermal effects of treatments such as infrared saunas, which are known to increase blood flow. Alzheimer's disease (AD) is associated with gradual decreases in brain blood flow and resulting dementia. In this study, we attempted to clarify the beneficial effects of far infrared light using the 5xFAD mouse, a transgenic model of AD. We exposed 5xFAD mice to far infrared light for 5 months. Among the far infrared-exposed AD mice, body weights were significantly decreased, and the levels of nerve growth factor and brain-derived neurotrophic factor protein were significantly increased in selected brain areas (compared to those in non-irradiated AD mice). However, cognition and motor function (as assessed by Morris water maze and Rota Rod tests, respectively) did not differ significantly between the irradiated and non-irradiated AD mouse groups. These results indicated that exposure to far infrared light may have beneficial biological effects in AD mice. However, the experimental schedule and methods may need to be modified to obtain clearer results.

RTP801/REDD1 contributes to neuroinflammation severity and memory impairments in Alzheimer's disease

RTP801/REDD1 is a stress-regulated protein whose upregulation is necessary and sufficient to trigger neuronal death. Its downregulation in Parkinson's and Huntington's disease models ameliorates the pathological phenotypes. In the context of Alzheimer's disease (AD), the coding gene for RTP801, DDIT4, is responsive to Aβ and modulates its cytotoxicity in vitro. Also, RTP801 mRNA levels are increased in AD patients' lymphocytes. However, the involvement of RTP801 in the pathophysiology of AD has not been yet tested. Here, we demonstrate that RTP801 levels are increased in postmortem hippocampal samples from AD patients. Interestingly, RTP801 protein levels correlated with both Braak and Thal stages of the disease and with GFAP expression. RTP801 levels are also upregulated in hippocampal synaptosomal fractions obtained from murine 5xFAD and rTg4510 mice models of the disease. A local RTP801 knockdown in the 5xFAD hippocampal neurons with shRNA-containing AAV particles ameliorates cognitive deficits in 7-month-old animals. Upon RTP801 silencing in the 5xFAD mice, no major changes were detected in hippocampal synaptic markers or spine density. Importantly, we found an unanticipated recovery of several gliosis hallmarks and inflammasome key proteins upon neuronal RTP801 downregulation in the 5xFAD mice. Altogether our results suggest that RTP801 could be a potential future target for theranostic studies since it could be a biomarker of neuroinflammation and neurotoxicity severity of the disease and, at the same time, a promising therapeutic target in the treatment of AD.

A Primary Care Agenda for Brain Health: A Scientific Statement From the American Heart Association

A healthy brain is critical for living a longer and fuller life. The projected aging of the population, however, raises new challenges in maintaining quality of life. As we age, there is increasing compromise of neuronal activity that affects functions such as cognition, also making the brain vulnerable to disease. Once pathology-induced decline begins, few therapeutic options are available. Prevention is therefore paramount, and primary care can play a critical role. The purpose of this American Heart Association scientific statement is to provide an up-to-date summary for primary care providers in the assessment and modification of risk factors at the individual level that maintain brain health and prevent cognitive impairment. Building on the 2017 American Heart Association/American Stroke Association presidential advisory on defining brain health that included "Life's Simple 7," we describe here modifiable risk factors for cognitive decline, including depression, hypertension, physical inactivity, diabetes, obesity, hyperlipidemia, poor diet, smoking, social isolation, excessive alcohol use, sleep disorders, and hearing loss. These risk factors include behaviors, conditions, and lifestyles that can emerge before adulthood and can be routinely identified and managed by primary care clinicians.

A method for the expression of fibroblast growth factor 14 and assessment of its neuroprotective effect in an Alzheimer's disease model

Background

Fibroblast growth factor (FGF) 14 is a member of the FGF family that is mainly expressed in the central nervous system. FGF14 has a close association with the occurrence of neurodegenerative conditions; however, its significance in Alzheimer’s disease (AD) has yet to be evaluated. Therefore, we sought to obtain a large amount of exogenous FGF14 protein and explore its effect in a cellular model of AD.

Methods

FGF14 protein was expressed in an Escherichia coli system using gene recombination technology. Purified protein was obtained through washing and renaturation of inclusion bodies combined with nickel column affinity chromatography. The AD model was established via Aβ25-35-induced injury in PC12 cells. Changes in the levels of lactate dehydrogenase and malondialdehyde were detected, and the neuroprotective effect of recombinant human FGF14 (rhFGF14) was evaluated through double-fluorescence staining and flow cytometry apoptosis detection. For further exploration of rhFGF14-mediated regulation of mitogen-activated protein kinase (MAPK) signaling, western blot was employed.

Results

We successfully induced large amounts of insoluble rhFGF14. Following solubilization and refolding of the rhFGF14 from inclusion bodies, high purity rhFGF14 was purified by Nickel affinity column chromatography. The results showed that rhFGF14 alleviated Aβ25-3-induced PC12 cell injury by inhibiting the phosphorylation of p38, extracellular signal-regulated kinase 1/2, and c-Jun N-terminal kinase, thus suppressing the MAPK signaling pathway.

Conclusions

FGF14 performed a neuroprotective role in our in vitro AD model via its inhibition of MAPK signaling, highlighting its potential as a therapeutic drug for neurodegenerative conditions.

Tetramethylpyrazine Improves Cognitive Function of Alzheimer's Disease Mice by Regulating SSTR4 Ubiquitination

Purpose

Many researches have investigated the functions of tetramethylpyrazine (TMP) in Alzheimer's disease (AD). This study aimed to discuss the underlying mechanism of TMP in AD mice.

Methods

TMP (200 mg/kg) was administered to 6-month-old APP/PS1 transgenic mice, and behavioral changes and hippocampal nerve injury in AD mice were detected. Apoptosis and autophagy-related protein levels were detected. Changes in gene expression before and after TMP treatment were compared using transcriptome sequencing. The effects of Cullin 4B (CUL4B) overexpression and somatostatin receptor 4 (SSTR4) silencing on AD symptoms and SSTR4 ubiquitination in APP/PS1 mice were observed. SH-SY5Y and PC12 cells were treated with 25 μmol/L Aβ_25-35 and TMP to observe cell viability, apoptosis, and autophagy. Cell viability and apoptosis were measured again after treatment with proteasome inhibitor MG132 or lysosomal inhibitor 3-mA.

Results

TMP treatment improved the behavioral cognition of APP/PS1 mice and improved the neuronal apoptosis and damage in brain tissue. CUL4B was significantly upregulated in APP/PS1 mouse brain tissue, and SSRT4 protein was downregulated, and the levels of CUL4B and SSRT4 were negatively correlated. TMP treatment downregulated CUL4B, inhibited SSRT4 ubiquitination and upregulated SSRT4 protein level in APP/PS1 mouse brain tissue, while CUL4B overexpression or SSRT4 silencing reversed the effect of TMP. TMP and MG132 improved the decreased activity, increased apoptosis and increased SSRT4 protein in SH-SY5Y and PC12 cells treated with Aβ_25-35, but not 3-mA. CUL4B overexpression promoted the ubiquitination of SSTR4 in cells, which partially reversed the effect of TMP.

Conclusion

TMP could improve the cognitive ability of AD mice by inhibiting CUL4B expression and the ubiquitination degradation of SSTR, and alleviating neuronal apoptosis and injury. This study may offer a new therapeutic option for AD treatment.

β-Amyloid in Cerebrospinal Fluid: How to Keep It Floating (Not Sticking) by Standardization of Preanalytic Processes and Collection Tubes

BACKGROUND

Phosphorylated tau (pTau), total tau (tTau), and β-amyloid (Aβ) are established cerebrospinal fluid (CSF) biomarkers used to help diagnose Alzheimer disease. Preanalytic workups of CSF samples lack harmonization, making interlaboratory comparison of these biomarkers challenging. The Aβ adsorbs to sample tubes, yielding underestimated concentrations, and may result in false Alzheimer disease diagnosis. Our primary aim was to compare Aβ recovery across multiple polypropylene tubes and to test the stability of tTau, pTau, and Aβ in the best performing tube.

METHODS

Eight polypropylene tubes were tested using 3 CSF pools with Aβ concentrations <500, 500-1000, and >1000 ng/L. All samples were analyzed in duplicate. Tubes were cut open to assess their different infrared adsorption spectra. Freshly drawn CSF from 14 patients was distributed into 4 Sarstedt 5-mL (no. 63.504.027; Sar5CSF) tubes, left at room temperature for up to 7 days, and analyzed for pTau, tTau, and Aβ by ELISA.

RESULTS

Two Sarstedt 5-mL tubes and a Sarstedt 10-mL (Sar10CSF) tube showed significantly higher Aβ recovery at all 3 concentrations compared with the 5 other tubes. The infrared adsorption spectra of Sar10CSF and Sar5CSF tubes were practically identical, unlike the other tubes. No significant loss of pTau, tTau, and Aβ was observed in CSF left at room temperature for up to 7 days (P > 0.05).

CONCLUSIONS

Recovery of Aβ from Sar5CSF tubes is equivalent to Aβ recovery from Sar10CSF tubes. Levels of pTau, tTau, and Aβ were stable for at least 7 days at room temperature but not at 37 °C.

The Impact of High Glucose or Insulin Exposure on S100B Protein Levels, Oxidative and Nitrosative Stress and DNA Damage in Neuron-Like Cells

Alzheimer’s disease (AD) is attracting considerable interest due to its increasing number of cases as a consequence of the aging of the global population. The mainstream concept of AD neuropathology based on pathological changes of amyloid β metabolism and the formation of neurofibrillary tangles is under criticism due to the failure of Aβ-targeting drug trials. Recent findings have shown that AD is a highly complex disease involving a broad range of clinical manifestations as well as cellular and biochemical disturbances. The past decade has seen a renewed importance of metabolic disturbances in disease-relevant early pathology with challenging areas in establishing the role of local micro-fluctuations in glucose concentrations and the impact of insulin on neuronal function. The role of the S100 protein family in this interplay remains unclear and is the aim of this research. Intracellularly the S100B protein has a protective effect on neurons against the toxic effects of glutamate and stimulates neurites outgrowth and neuronal survival. At high concentrations, it can induce apoptosis. The aim of our study was to extend current knowledge of the possible impact of hyper-glycemia and -insulinemia directly on neuronal S100B secretion and comparison to oxidative stress markers such as ROS, NO and DBSs levels. In this paper, we have shown that S100B secretion decreases in neurons cultured in a high-glucose or high-insulin medium, while levels in cell lysates are increased with statistical significance. Our findings demonstrate the strong toxic impact of energetic disturbances on neuronal metabolism and the potential neuroprotective role of S100B protein.

Virtual Reality-Based Cognitive Stimulation on People with Mild to Moderate Dementia due to Alzheimer's Disease: A Pilot Randomized Controlled Trial

The use of ecologically oriented approaches with virtual reality (VR) depicting instrumental activities of daily living (IADL) is a promising approach for interventions on acquired brain injuries. However, the results of such an approach on dementia caused by Alzheimer’s disease (AD) are still lacking. This research reports on a pilot randomized controlled trial that aimed to explore the effect of a cognitive stimulation reproducing several IADL in VR on people with mild-to-moderate dementia caused by AD. Patients were recruited from residential care homes of Santa Casa da Misericórdia da Amadora (SCMA), which is a relevant nonprofit social and healthcare provider in Portugal. This intervention lasted two months, with a total of 10 sessions (two sessions/week). A neuropsychological assessment was carried out at the baseline and follow-up using established neuropsychological instruments for assessing memory, attention, and executive functions. The sample consisted of 17 patients of both genders randomly assigned to the experimental and control groups. The preliminary results suggested an improvement in overall cognitive function in the experimental group, with an effect size corresponding to a large effect in global cognition, which suggests that this approach is effective for neurocognitive stimulation in older adults with dementia, contributing to maintaining cognitive function in AD.

Preparation of a CaTiO3/Al3+/Pr3+/Sm3+ nanocomposite for enrichment of exosomes in human serum

Exosomes (30-200 nm) play important roles in intercellular communication. Because their contents differ between healthy individuals and subjects diagnosed with various diseases, exosomes have been regarded as potential sources of biomarkers for clinical diagnosis. However, the accuracy of diagnosis by exosomal biomarkers is highly dependent on the extraction efficiency, yield, and the quality of exosomes. Hence, inexpensive, convenient, and fast exosome separation methods are required. In the present study, the CaTiO₃/Al³⁺/Pr³⁺/Sm³⁺ nanocomposite was synthesized and applied in highly selective and efficient separation of exosomes. Notably, the developed material exhibited higher specificity and efficiency than commercially available TiO₂. Moreover, CaTiO₃/Al³⁺/Pr³⁺/Sm³⁺ could be reused at least three times without any significant decrease in efficiency. The synthesized material was also used for the extraction of exosomes from the serums of patients with Alzheimer's disease (AD) and healthy controls. The exosomes were subjected to two-dimensional gel electrophoresis (2-DE) separation and matrix-assisted laser desorption/ionization-time of flight (MALDI TOF/TOF) mass spectrometry analysis. It was found that five proteins in the exosomes were evidently upregulated, while one protein was downregulated. Among the detected proteins, serum amyloid P-component (SAP) has been reported to be closely related to pathogenesis of AD. The obtained results indicated that the developed method involving separation and analysis of serum exosomes could be used for disease diagnosis or postoperative clinical monitoring.

Design, synthesis and evaluation of cholinesterase hybrid inhibitors using a natural steroidal alkaloid as precursor

To date, Alzheimer's disease is the most alarming neurodegenerative disorder worldwide. This illness is multifactorial in nature and cholinesterase inhibitors have been the ones used in clinical treatments. In this context, many of these drugs selectively inhibit the acetylcholinesterase enzyme interacting in both the active site and the peripheric anionic site. Besides, some agents have exhibited extensive benefits being able to co-inhibit butyrylcholinesterase. In this contribution, a strategy previously explored by numerous authors is reported; the synthesis of hybrid cholinesterase inhibitors. This strategy uses a molecule of recognized high inhibitory activity (tacrine) together with a steroidal alkaloid of natural origin using different connectors. The biological assays demonstrated the improvement in the inhibitory activity compared to the alkaloidal precursor, together with the reinforcement of the interactions in multiple sites of the enzymatic cavity. This strategy should be explored and exploited in this area. Docking and molecular dynamic studies were performed to explain enzyme-ligand interactions, assisting a structure-activity relationship analysis.

Mild Cognitive Impairment and Mild Dementia: The Role of Ginkgo biloba (EGb 761®)

Mild cognitive impairment (MCI) and dementia are clinically prevalent in the elderly. There is a high risk of cognitive decline in patients diagnosed with MCI or dementia. This review describes the effectiveness of Ginkgo biloba leaf special extract EGb 761^® for the treatment of dementia syndromes and EGb 761^® combination therapy with other medications for symptomatic dementia. This drug has shown convincing results, improving cognitive function, neuropsychiatric symptoms and consequent reduction of caregiver stress and maintenance of autonomy in patients with age-related cognitive decline, MCI and mild to moderate dementia. Currently, there is little evidence to support the combination therapy with anti-dementia drugs and, therefore, more evidence is needed to evaluate the role of EGb 761^® in mixed therapy.

Amyloid Structural Changes Studied by Infrared Microspectroscopy in Bigenic Cellular Models of Alzheimer's Disease

Alzheimer's disease affects millions of lives worldwide. This terminal disease is characterized by the formation of amyloid aggregates, so-called amyloid oligomers. These oligomers are composed of β-sheet structures, which are believed to be neurotoxic. However, the actual secondary structure that contributes most to neurotoxicity remains unknown. This lack of knowledge is due to the challenging nature of characterizing the secondary structure of amyloids in cells. To overcome this and investigate the molecular changes in proteins directly in cells, we used synchrotron-based infrared microspectroscopy, a label-free and non-destructive technique available for in situ molecular imaging, to detect structural changes in proteins and lipids. Specifically, we evaluated the formation of β-sheet structures in different monogenic and bigenic cellular models of Alzheimer's disease that we generated for this study. We report on the possibility to discern different amyloid signatures directly in cells using infrared microspectroscopy and demonstrate that bigenic (amyloid-β, α-synuclein) and (amyloid-β, Tau) neuron-like cells display changes in β-sheet load. Altogether, our findings support the notion that different molecular mechanisms of amyloid aggregation, as opposed to a common mechanism, are triggered by the specific cellular environment and, therefore, that various mechanisms lead to the development of Alzheimer's disease.

Microglial phagocytosis of neurons in neurodegeneration, and its regulation

There is growing evidence that excessive microglial phagocytosis of neurons and synapses contributes to multiple brain pathologies. RNA-seq and genome-wide association (GWAS) studies have linked multiple phagocytic genes to neurodegenerative diseases, and knock-out of phagocytic genes has been found to protect against neurodegeneration in animal models, suggesting that excessive microglial phagocytosis contributes to neurodegeneration. Here, we review recent evidence that microglial phagocytosis of live neurons and synapses causes neurodegeneration in animal models of Alzheimer's disease and other tauopathies, Parkinson's disease, frontotemporal dementias, multiple sclerosis, retinal degeneration and neurodegeneration induced by ischaemia, infection or ageing. We also review factors regulating microglial phagocytosis of neurons, including: nucleotides, frackalkine, phosphatidylserine, calreticulin, UDP, CD47, sialylation, complement, galectin-3, Apolipoprotein E, phagocytic receptors, Siglec receptors, cytokines, microglial epigenetics and expression profile. Some of these factors may be potential treatment targets to prevent neurodegeneration mediated by excessive microglial phagocytosis of live neurons and synapses.

Lacidipine Prevents Scopolamine-Induced Memory Impairment by Reducing Brain Oxido-nitrosative Stress in Mice

Cholinergic deficits and oxido-nitrosative stress are consistently associated with Alzheimer's disease (AD). Previous findings indicate that acetylcholine subdues Ca²⁺ current in the brain. Cholinergic antagonists (e.g., scopolamine) can instigate Ca²⁺-induced redox imbalance, inflammation, and cell-death pathways leading to AD-type memory impairment. Earlier, several Ca²⁺-channel blockers (CCB, e.g., dihydropyridine type) or cholinergic enhancers showed promising results in animal models of AD. In the present research, pretreatment effects of lacidipine (L-type CCB) on learning and memory functions were investigated using the scopolamine mouse model of AD. Swiss albino mice (20-25 g) were administered lacidipine (1 and 3 mg/kg) for 14 days. Scopolamine, an anti-muscarinic drug, was given (1 mg/kg) from days 8 to 14. The mice were subjected to elevated plus maze (EPM) and passive-avoidance (PA) paradigms. Bay-K8644 (a Ca²⁺-channel agonist) was administered before behavioral studies on days 13 and 14. Biochemical parameters of oxidative stress and acetylcholinesterase (AChE) activity were quantified using the whole brain. Behavioral studies showed an increase in transfer latency (TL) in the EPM test and a decrease in step-through latency (STL) in the PA test in scopolamine-administered mice. Scopolamine enhanced the AChE activity and oxidative stress in the brain of mice which resulted in memory impairment. Lacidipine prevented the amnesia against scopolamine and reduced the oxidative stress and AChE activity in the brain of mice. Bay-K8644 attenuated the lacidipine-induced improvement in memory and redox balance in scopolamine-administered mice. Lacidipine can prevent the oxidative stress and improve the cholinergic function in the brain. These properties of lacidipine can mitigate the pathogenesis of AD-type dementia.

Cardiovascular risk and midlife cognitive decline in the Study of Women's Health Across the Nation

INTRODUCTION

Cardiovascular risk factors in midlife have been linked to late life risk for Alzheimer's disease and related dementias (ADRD). The relation of vascular risk factors on cognitive decline within midlife has been less studied.

METHODS

Using data from the Study of Women's Health Across the Nation, we examined associations of midlife hypertension, elevated lipid levels, diabetes, fasting glucose, central adiposity, and Framingham heart age with rates of cognitive decline in women who completed multiple cognitive assessments of processing speed, and working and verbal memory during midlife.

RESULTS

Diabetes, elevated fasting glucose, central obesity, and heart age greater than chronological age were associated with rate of decline in processing speed during midlife. Vascular risk factors were not related to rate of decline in working or verbal memory.

DISCUSSION

Midlife may be a critical period for intervening on cardiovascular risk factors to prevent or delay later life cognitive impairment and ADRD.

Molecular Mechanism of Vitamin K2 Protection against Amyloid-β-Induced Cytotoxicity

The pathological role of vitamin K2 in Alzheimer's disease (AD) involves a definite link between impaired cognitive functions and decreased serum vitamin K levels. Vitamin K2 supplementation may have a protective effect on AD. However, the mechanism underlying vitamin K2 protection has not been elucidated. With the amyloid-β (Aβ) cascade hypothesis, we constructed a clone containing the C-terminal fragment of amyloid precursor protein (β-CTF/APP), transfected in astroglioma C6 cells and used this cell model (β-CTF/C6) to study the protective effect of vitamin K2 against Aβ cytotoxicity. Both cellular and biochemical assays, including cell viability and reactive oxygen species (ROS), assays assay, and Western blot and caspase activity analyses, were used to characterize and unveil the protective role and mechanism of vitamin K2 protecting against Aβ-induced cytotoxicity. Vitamin K2 treatment dose-dependently decreased the death of neural cells. The protective effect of vitamin K2 could be abolished by adding warfarin, a vitamin K2 antagonist. The addition of vitamin K2 reduced the ROS formation and inhibited the caspase-3 mediated apoptosis induced by Aβ peptides, indicating that the mechanism underlying the vitamin K2 protection is likely against Aβ-mediated apoptosis. Inhibitor assay and Western blot analyses revealed that the possible mechanism of vitamin K2 protection against Aβ-mediated apoptosis might be via regulating phosphatidylinositol 3-kinase (PI3K) associated-signaling pathway and inhibiting caspase-3-mediated apoptosis. Our study demonstrates that vitamin K2 can protect neural cells against Aβ toxicity.

A novel small-molecule PROTAC selectively promotes tau clearance to improve cognitive functions in Alzheimer-like models

Intracellular accumulation of tau is a hallmark pathology in Alzheimer disease (AD) and the related tauopathies, thus targeting tau could be promising for drug development. Proteolysis Targeting Chimera (PROTAC) is a novel drug discovery strategy for selective protein degradation from within cells. Methods: A novel small-molecule PROTAC, named as C004019 with a molecular mass of 1,035.29 dalton, was designed to simultaneously recruite tau and E3-ligase (Vhl) and thus to selectively enhance ubiquitination and proteolysis of tau proteins. Western blotting, immunofluoresence and immunohistochemical staining were employed to verify the effects of C004019 in cell models (HEK293 and SH-SY5Y) and mouse models (hTau-transgenic and 3xTg-AD), respectively. The cognitive capacity of the mice was assessed by a suite of behavior experiments. Electrophysiology and Golgi staining were used to evaluate the synaptic plasticity. Results: C004019 induced a robust tau clearance via promoting its ubiquitination-proteasome-dependent proteolysis in HEK293 cells with stable or transient overexpression of human tau (hTau), and in SH-SY5Y that constitutively overexpress hTau. Furthermore, intracerebral ventricular infusion of C004019 induced a robust tau clearance in vivo. Most importantly, both single-dose and multiple-doses (once per 6 days for a total 5 times) subcutaneous administration of C004019 remarkably decreased tau levels in the brains of wild-type, hTau-transgenic and 3xTg-AD mice with improvement of synaptic and cognitive functions. Conclusions: The PROTAC (C004019) created in the current study can selectively and efficiently promote tau clearance both in vitro and in vivo, which provides a promising drug candidate for AD and the related tauopathies.