A critical appraisal of amyloid-β-targeting therapies for Alzheimer disease

Multi-target macrocycles: pyrogallol derivatives to control multiple pathological factors associated with Alzheimer's disease

Designing multi-target chemical tools is a vital approach to understanding the pathology of Alzheimer's disease (AD), which involves a complex network of pathological factors, such as free organic radicals, amyloid-β (Aβ), and metal-bound Aβ (metal-Aβ). The pyrogallol moiety, known for its ability to lower redox potentials and interact with both Aβ and metal ions, presents a promising framework for this molecular design. Here we show how simple structural variations of pyrogallol can be used to enhance its ability to scavenge free organic radicals and regulate the aggregation of both metal-free Aβ and metal-Aβ. By incorporating multiple pyrogllol units into a macrocyclic scaffold via methylene bridges, we achieve synergistic reactivity against several pathological targets. Our structure-reactivity relationship studies also reveal that the macrocyclic structure noticeably improves antioxidant activity as well as interactions with both Aβ and metal ions, leading to oxidation of Aβ peptides and influencing their conformation and aggregation in both the absence and presence of metal ions. This work demonstrates the potential of simple redox-active structural entities in developing multifunctional chemical reagents that effectively manage the pathological components associated with AD.

Association between the platelet/high-density lipoprotein cholesterol ratio and depression: A cross-sectional analysis in United States adults

BACKGROUND

The primary objective of this study was to elucidate the relationship between the platelet/high-density lipoprotein cholesterol ratio (PHR) and the risk of depression in adults in the US.

METHODS

We conducted a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2016. Depression was assessed using the PHQ-9 questionnaire. Weighted multivariable logistic regression models and restricted cubic spline (RCS) models were used to study the relationship between PHR and the risk of depression. Subgroup and interaction analyses were performed to further understand these associations.

RESULTS

A total of 21,454 participants were included in this study. After full adjustment, PHR was significantly positively correlated with depression (OR = 1.33, 95%CI: 1.03-1.73). When PHR was converted into a categorical variable based on quartiles (Q1-Q4), the highest quartile of PHR was associated with an increased risk of depression compared to the lowest reference group (OR = 1.22, 95%CI: 1.01-1.48). There was a linear dose-response relationship between PHR and the risk of depression (P-non-linear = 0.8038). The association remained significant in several subgroup analyses. However, the interaction test showed that none of the stratified variables were significant (all P for interaction >0.05).

LIMITATION

Using self-assessment scales and inability to assess causality.

CONCLUSION

This population-based cross-sectional study elucidated that PHR is significantly associated with an increased prevalence of depression in adults in the US.

Chaotic recurrent neural networks for brain modelling: A review

Even in the absence of external stimuli, the brain is spontaneously active. Indeed, most cortical activity is internally generated by recurrence. Both theoretical and experimental studies suggest that chaotic dynamics characterize this spontaneous activity. While the precise function of brain chaotic activity is still puzzling, we know that chaos confers many advantages. From a computational perspective, chaos enhances the complexity of network dynamics. From a behavioural point of view, chaotic activity could generate the variability required for exploration. Furthermore, information storage and transfer are maximized at the critical border between order and chaos. Despite these benefits, many computational brain models avoid incorporating spontaneous chaotic activity due to the challenges it poses for learning algorithms. In recent years, however, multiple approaches have been proposed to overcome this limitation. As a result, many different algorithms have been developed, initially within the reservoir computing paradigm. Over time, the field has evolved to increase the biological plausibility and performance of the algorithms, sometimes going beyond the reservoir computing framework. In this review article, we examine the computational benefits of chaos and the unique properties of chaotic recurrent neural networks, with a particular focus on those typically utilized in reservoir computing. We also provide a detailed analysis of the algorithms designed to train chaotic RNNs, tracing their historical evolution and highlighting key milestones in their development. Finally, we explore the applications and limitations of chaotic RNNs for brain modelling, consider their potential broader impacts beyond neuroscience, and outline promising directions for future research.

Nuclear respiratory factor-1 (NRF1) induction drives mitochondrial biogenesis and attenuates amyloid beta-induced mitochondrial dysfunction and neurotoxicity

Mitochondrial dysfunction is an important driver of neurodegeneration and synaptic abnormalities in Alzheimer's disease (AD). Amyloid beta (Aβ) in mitochondria leads to increased reactive oxygen species (ROS) production, resulting in a vicious cycle of oxidative stress in coordination with a defective electron transport chain (ETC), decreasing ATP production. AD neurons exhibit impaired mitochondrial dynamics, evidenced by fusion and fission imbalances, increased fragmentation, and deficient mitochondrial biogenesis, contributing to fewer mitochondria in brains of AD patients. Nuclear respiratory factor-1 (NRF1) is a regulator of mitochondrial biogenesis through its activation of mitochondrial transcription factor A (TFAM). Our hypothesis posited that NRF1 induction in neuronal cells exposed to amyloid β1-42 (Aβ1-42) would increase de novo mitochondrial synthesis and improve mitochondrial function, restoring neuronal survival. Following NRF1 messenger RNA (mRNA) transfection of Aβ1-42-treated SH-SY5Y cells, a marked increase in mitochondrial mass was observed. Metabolic programming toward enhanced oxidative phosphorylation resulted in increased ATP production. Oxidative stress in the form of mitochondrial ROS accumulation was reduced and mitochondrial membrane potential preserved. Mitochondrial homeostasis was maintained, evidenced by balanced fusion and fission processes. Ultimately, improvement of mitochondrial function was associated with significant decreases in Aβ1-42-induced neuronal death and neurite disruption. Our findings highlight the potential of NRF1 upregulation to counteract Aβ1-42-associated mitochondrial dysfunction and neurodegenerative cell processes, opening avenues for innovative therapeutic approaches aimed at safeguarding mitochondrial health in AD neurons.

Hearing modulation affects Alzheimer's disease progression linked to brain inflammation: a study in mouse models

BACKGROUND

Recent studies have identified hearing loss (HL) as a primary risk factor for Alzheimer's disease (AD) onset. However, the mechanisms linking HL to AD are not fully understood. This study explored the effects of drug-induced hearing loss (DIHL) on the expression of proteins associated with AD progression in mouse models.

METHODS

DIHL was induced in 5xFAD and Tg2576 mice aged 3 to 3.5 weeks using kanamycin (700 mg/kg, subcutaneous) and furosemide (600 mg/kg, intraperitoneal). The accumulation and expression of beta-amyloid (Aβ), ionized calcium-binding adaptor molecule 1 (Iba1), and glial fibrillary acidic protein (GFAP) were measured through immunohistochemistry and immunoblotting. Additionally, the expression of proteins involved in the mammalian target of rapamycin (mTOR) pathway, including downstream effectors p70 ribosomal S6 kinase (p70S6K) and S6, as well as proinflammatory cytokines, was analyzed.

RESULTS

Compared to control conditions, HL led to a significant increase in the accumulation of Aβ in the hippocampus and cortex. Elevated levels of neuroinflammatory markers, including Iba1 and GFAP, as well as proinflammatory cytokines such as interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α), were observed. Moreover, DIHL enhanced phosphorylation of mTOR, p70S6K, and S6, indicating activation of the mTOR pathway.

CONCLUSIONS

HL significantly increases Aβ accumulation in the brain. Furthermore, HL activates astrocytes and microglia, leading to increased neuroinflammation and thereby accelerating AD progression. These findings strongly suggest that HL contributes autonomously to neuroinflammation, highlighting the potential for early intervention in HL to reduce AD risk.

Carboxylated Zn-phthalocyanine attenuates brain Aβ in AD model mouse

The deposition of aggregated amyloid β (Aβ) is considered as a key factor for Alzheimer's Disease (AD). Previously, we demonstrated that a carboxylated Zn-phthalocyanine (ZnPc) inhibits Aβ fibril formation, consequently protects neurons in culture. This study evaluated the effects of ZnPc on pathological changes in an AD mouse model (J20). Nine-month-old J20 mice received weekly intraperitoneal injection of ZnPc (2 and 4 mg/kg) for 12 weeks. Cognitive performance was assessed using Y-maze and open field tests. ZnPc levels in the tissues were evaluated using near-infrared microscopy and spectroscopy. ZnPc accumulated primarily in the liver and kidney. A considerable amount was also detected in brain tissue, where it co-localized with neurons, microglia, and extracellularly deposited Aβ. ZnPc treatment (2 mg/kg) significantly improved cognitive functions of J20 mice. Immunostaining results showed that Aβ was positive intracellularly in neurons, and extracellularly around the vessels and parenchyma in the cortex and hippocampus of PBS-treated J20 mice, which was significantly decreased in ZnPc-treated J20 mice in a dose-dependent manner. Nissl staining demonstrated that neuronal numbers were increased both in the cortex and hippocampus. GFAP-positive astrocytes and Iba-1 positive microglia were decreased by ZnPc treatment. Also, vessel numbers were increased in ZnPc-treated groups. In PBS-treated group, aquaporin 4 immunopositive area extended beyond STL-positive vessels into the parenchyma, which was confined primarily around the vessels in the ZnPc-treated group. Claudin 5 levels were increased in ZnPc-treated group. Therefore, ZnPc can decrease brain Aβ deposition in J20 mice, suggesting it as a potential therapeutic agent for AD.

Unveiling the Potential of Tetrahedral DNA Frameworks in Clinical Medicine: Mechanisms, Advances, and Future Perspectives

As deoxyribonucleic acis (DNA) nanotechnology advances, DNA, a fundamental biological macromolecule, has been employed to treat various clinical diseases. Among the advancements in this field, tetrahedral frameworks nucleic acids (tFNAs) have gained significant attention due to their straightforward design, structural simplicity, low cost, and high yield since their introduction by Turberfield in the early 2000s. Due to its stable spatial structure, tFNAs can resist the impact of innate immune responses on DNA and nuclease activity. Meanwhile, structural programmability of tFNAs allows for the development of static tFNA-based nanomaterials through the engineering of functional oligonucleotides or therapeutic molecules and dynamic tFNAs through the attachment of stimuli-responsive DNA apparatuses. This review first summarizes the key merits of tFNAs, including natural biocompatibility, biodegradability, structural stability, unparalleled programmability, functional diversity, and efficient cellular internalization. Based on these strengths, this review comprehensively analyzes applications of tFNAs in different clinical settings, including orthopedics, stomatology, urinary system diseases, liver-related diseases, tumors, infection, neural system diseases, ophthalmic diseases, and immunoprophylaxis. We also discuss the limitations of tFNAs and the challenges encountered in preclinical studies. This review provides new perspectives for future research and valuable guidance for researchers working in this field.

Can brain network connectivity facilitate the clinical development of disease-modifying anti-Alzheimer drugs?

The preclinical phase of Alzheimer's disease represents a crucial time window for therapeutic intervention but requires the identification of clinically relevant biomarkers that are sensitive to the effects of disease-modifying drugs. Amyloid peptide and tau proteins, the main histological hallmarks of Alzheimer's disease, have been widely used as biomarkers of anti-amyloid and anti-tau drugs. However, these biomarkers do not fully capture the multiple biological pathways of the brain. Indeed, robust amyloid-target engagement by anti-amyloid monoclonal antibodies has recently translated into modest cognitive and clinical benefits in Alzheimer's disease patients, albeit with potentially life-threatening side effects. Moreover, targeting the tau pathway has yet to result in any positive clinical outcomes. Findings from computational neuroscience have demonstrated that brain regions do not work in isolation but are interconnected within complex network structures. Brain connectivity studies suggest that misfolded proteins can spread through these connections, leading to the hypothesis that Alzheimer's disease is a pathology of network disconnectivity. Based on these assumptions, here we discuss how incorporating brain connectivity outcomes could better capture global brain functionality and, in conjunction with traditional Alzheimer's disease biomarkers, could facilitate the clinical development of new disease-modifying anti-Alzheimer's disease drugs.

Network Pharmacology, Molecular Docking, and In Vitro Insights into the Potential of Mitragyna speciosa for Alzheimer's Disease

Mitragyna speciosa Korth. Havil (MS) has a traditional use in relieving pain, managing hypertension, treating cough, and diarrhea, and as a morphine substitute in addiction recovery. Its potential in addressing Alzheimer's disease (AD), a neurodegenerative condition with no effective treatments, is under investigation. This study aims to explore MS mechanisms in treating AD through network pharmacology, molecular docking, and in vitro studies. Using network pharmacology, we identified 19 MS components that may affect 60 AD-related targets. The compound-target network highlighted significant interactions among 60 nodes and 470 edges, with an average node degree of 15.7. The KEGG enrichment analysis revealed Alzheimer's disease (hsa05010) as a relevant pathway. We connected 20 targets to tau and β-amyloid proteins through gene expression data from the AlzData database. Docking studies demonstrated high binding affinities of MS compounds like acetylursolic acid, beta-sitosterol, isomitraphylline, and speciophylline to AD-related proteins, such as AKT1, GSK3B, NFκB1, and BACE1. In vitro studies showed that ethanolic (EE), distilled water (DWE), and pressurized hot water (PHWE) extracts of MS-treated 100 μM H2O2-induced SH-SY5Y cells significantly reduced oxidative damage. This research underscores the multi-component, multi-target, and multi-pathway effects of MS on AD, providing insights for future research and potential clinical applications.

PDE4D inhibitors: Opening a new era of PET diagnostics for Alzheimer's disease

As the incidence of Alzheimer's disease (AD) continues to rise, the need for an effective PET radiotracer to facilitate early diagnosis has become more pressing than ever before in modern medicine. Phosphodiesterase (PDE) is closely related to cognitive impairment and neuroinflammatory processes in AD. Current research progress shows that specific PDE4D inhibitors radioligands can bind specifically to the PDE4D enzyme in the brain, thereby showing pathology-related signal enhancement in AD animal models, indicating the potential of these ligands as effective radiotracers. At the same time, we need to pay attention to the important role computer aided drug design (CADD) plays in advancing AD drug design and PET imaging. Future research will verify the potential of these ligands in clinical applications through computer simulation techniques, providing patients with timely intervention and treatment, which is of great significance.

Covalent organic framework-based ratiometric electrochemical sensing platform for ultrasensitive determination of amyloid-β 42 oligomer

Accurate and sensitive detection of amyloid-β 42 oligomer (Aβ42O) is of great significance for early diagnosis of Alzheimer's disease (AD). Herein, a signal on-off ratiometric electrochemical immunosensor was developed for highly selective and quantitative determination of Aβ42O by using novel covalent organic frameworks (COFs) composites as the sensing platform. This immunosensor produced two independent electrochemical signals from the [Fe(CN)6]3-/4- and methylene blue (MB) probes at different potentials based on the electrocatalytic activity of gold nanoparticle-functionalized porphyrinyl COFs nanocomposites toward [Fe(CN)6]3-/4- and the signal probe of MB encapsulated in the aptamer-modified alkynyl COFs. Because the two signals of [Fe(CN)6]3-/4- and MB changed in opposite directions, a signal on-off mode was generated which can correct the results by introducing a reference signal and effectively eliminate background interference. Under optimal experimental conditions, the current ratio (IMB/I[Fe(CN)6]3-/4-) was well linearly related to the logarithmic value of Aβ42O concentrations in the range of 10 pM to 1 μM, and the detection limit was 5.1 pM (S/N = 3). Additionally, the immunosensor exhibited satisfactory performance in case of real cerebrospinal fluid samples. The designed ratiometric electrochemical immunosensor provides a valuable route for early diagnosis of AD and our results also pave the way for designing of sensing platforms using COF-based nanomaterials and extending their functions and applications to bioanalysis.

Euonymus hamiltonianus Extract Improves Amnesia in APPswe/Tau Transgenic and Scopolamine-Induced Dementia Models

Dementia is a syndrome exhibiting progressive impairments on cognition and behavior beyond the normal course of aging, and Alzheimer's disease (AD) is one of the neurodegenerative diseases known to cause dementia. We investigated the effect of KGC07EH, the 30% ethanol extract of Euonymus hamiltonianus, against amyloid-β (Aβ) production and cognitive dysfunction in dementia models. KGC07EH was treated on Hela cells expressing the Swedish mutant form of amyloid precursor protein (APP), and the AD triple transgenic (3× TG) mice were given KGC07EH orally during 11-14 months of age (100 and 300 mg/kg/day). SH-SY5Y cell line was used to test KGC07EH on scopolamine-induced elevation of acetylcholinesterase (AChE) activity. ICR mice were intraperitoneally injected with scopolamine, and KGC07EH was administered orally (50, 100, and 200 mg/kg/day) for 4 weeks. KGC07EH treatment decreased Aβ, sAPPβ-sw, and sAPPβ-wt levels and APP protein expressions while sAPPα was increased in Swedish mutant-transfected HeLa cells. KGC07EH treatment also significantly reduced the accumulation of Aβ plaques and tau tangles in the brain of 3× TG mice as well as improving the cognitive function. In SH-SY5Y cells cultured with scopolamine, KGC07EH dose-dependently attenuated the increase of AChE activity. KGC07EH also improved scopolamine-induced learning and memory impairment in scopolamine-injected mice, and in their cerebral cortex and hippocampus, the expression levels of p-ERK, p-CREB, p-Akt, and BDNF were attenuated. KGC07EH inhibits APP processing and Aβ production both in vitro and in vivo, while enhancing acetylcholine signaling and cognitive dysfunction which are the major symptoms of dementia.

A biomimetic upconversion nanoreactors for near-infrared driven H2 release to inhibit tauopathy in Alzheimer's disease therapy

Abnormal hyperphosphorylation of tau protein is a principal pathological hallmark in the onset of neurodegenerative disorders, such as Alzheimer's disease (AD), which can be induced by an excess of reactive oxygen species (ROS). As an antioxidant, hydrogen gas (H2) has the potential to mitigate AD by scavenging highly harmful ROS such as •OH. However, conventional administration methods of H2 face significant challenges in controlling H2 release on demand and fail to achieve effective accumulation at lesion sites. Herein, we report artificial nanoreactors that mimic natural photosynthesis to realize near-infrared (NIR) light-driven photocatalytic H2 evolution in situ. The nanoreactors are constructed by biocompatible crosslinked vesicles (CVs) encapsulating ascorbic acid and two photosensitizers, chlorophyll a (Chla) and indoline dye (Ind). In addition, platinum nanoparticles (Pt NPs) serve as photocatalysts and upconversion nanoparticles (UCNP) act as light-harvesting antennas in the nanoreacting system, and both attach to the surface of CVs. Under NIR irradiation, the nanoreactors release H2 in situ to scavenge local excess ROS and attenuate tau hyperphosphorylation in the AD mice model. Such NIR-triggered nanoreactors provide a proof-of-concept design for the great potential of hydrogen therapy against AD.

Dual inhibition of butyrylcholinesterase and p38α mitogen-activated protein kinase: A new approach for the treatment of Alzheimer's disease

The simultaneous targeting of neuroinflammation and cholinergic hypofunction, the key pathological changes in Alzheimer's disease (AD), is not addressed by drugs currently in clinical trials, highlighting a critical therapeutic gap. We propose that dual-acting small molecules that inhibit butyrylcholinesterase (BChE) and mitogen-activated protein kinase p38α (p38α MAPK) represent a novel strategy to combat AD. This hypothesis is supported by cellular and animal studies as well as in silico modelling showing that it is possible to act simultaneously on both enzymes. Amyloid beta (Aβ) plaques trigger a pro-inflammatory microglial response that overactivates p38α MAPK, leading to increased Aβ synthesis, tau hyperphosphorylation, and altered synaptic plasticity. Overactivated microglia exacerbate neuroinflammation and cholinergic degeneration, ultimately leading to cognitive impairment. Structural similarities between the binding sites of BChE and p38α MAPK provide a promising basis for the development of dual inhibitors that could alleviate AD symptoms and address the underlying pathology.

The new perspective of Alzheimer's Disease Research: Mechanism and therapeutic strategy of neuronal senescence

Alzheimer's disease (AD), commonly known as senile dementia, is a neurodegenerative disease with insidious onset and gradually worsening course. The brain is particularly sensitive to senescence, and neuronal senescence is an important risk factor for the occurrence of AD. However, the exact pathogenesis between neuronal senescence and AD has not been fully elucidated so far. Neuronal senescence is characterized by the permanent stagnation of the cell cycle, and the changes in its structure, function, and microenvironment are closely related to the pathogenesis and progression of AD. In recent years, studies such as the Aβ cascade hypothesis and Tau protein phosphorylation have provided new strategies for the therapy of AD, but due to the complexity of the etiology of AD, there are still no effective treatment measures. This article aims to deeply analyze the pathogenesis between AD and neuronal senescence, and sort out various existing therapeutic methods, to provide new ideas and references for the clinical treatment of AD.

Dimerization of the Aβ42 under the Influence of the Gold Nanoparticle: A REMD Study

Advances in Alzheimer's disease (AD) are related to the oligomerization of Amyloid β (Aβ) peptides. Therefore, alteration of the process can prevent AD. We investigated the Aβ42 dimerization under the effects of gold nanoparticles using temperature replica-exchange molecular dynamics (REMD) simulations. The structural change of dimers in the presence and absence of the gold nanoparticle, Au55, was monitored over stable intervals. Physical insights into the oligomerization of Aβ were thus clarified. The computed metrics indicate that Au55 affects the progress of oligomerization. Specifically, the presence of the gold nanoparticle significantly modifies the structure of dimeric Aβ42. The β-content experienced a substantial decrease with the induction of Au55. The turn and coil-contents are also decreased under the effects of the gold nanoparticle. However, the α-content of the dimer exhibited a rigid increase. The influence of gold nanoparticles on the dimeric Aβ42 differs significantly from that of silver nanoparticles, which reduce β-content but increase coil-, turn-, and α-contents. The nature of inhibition will be discussed, in which the vdW interaction plays a driving force for the interaction between the Aβ42 dimer and the gold nanoparticle.

Eplingiella fruticosa leaf essential oil complexed with β-cyclodextrin exerts a neuroprotective effect in an Alzheimer's disease animal model induced by Streptozotocin

Alzheimer's Disease (AD) is physiopathologically marked by an accumulation of beta-amyloid peptide (Aβ), hyperphosphorylation of tau protein, inflammation, and oxidative stress in the brain tissue. While new drugs for AD have been approved, novel treatments are still needed. Eplingiella fruticosa (EF) has demonstrated anti-inflammatory and antioxidant properties, which may be beneficial against AD. This study aimed to evaluate the effects of EF leaf essential oil complexed with β-cyclodextrin in a sporadic AD model induced by streptozotocin (STZ). Male Wistar rats (5-6 months old) received an intracerebroventricular STZ injection (3 mg/kg) or vehicle, and were orally treated with vehicle, EF (5 mg/kg), or donepezil (5 mg/kg) for 14 days. Behavioral tests included olfactory discrimination, open field, novel object recognition, sucrose preference, and spontaneous alternation. Upon completion, rats were euthanatized, and their brains were analyzed for Aβ, tau, and IL-1β via immunohistochemistry, and for oxidative stress markers. STZ-treated rats showed memory deficits and anhedonia, accompanied by increased Aβ, tau, and IL-1β immunoreactivity in the olfactory bulb, cortex, hippocampus, and increased TBARS levels in the hippocampus. On the other hand, EF treatment improved short-term and working memory (p < 0.001), and reduced depressive-like behavior (p = 0.02). Additionally, EF treatment decreased Aβ, tau, and IL-1β immunoreactivity in the olfactory bulb, hippocampus and cortex (p < 0.05), and reduced TBARS levels (p = 0.04) and total oxidant status in the hippocampus (p = 0.03), and increased total antioxidant status in the cortex (p = 0.04). These findings suggest EF has neuroprotective effects against STZ-induced damage, indicating its potential as a novel compound for AD treatment.

Calcium balance through mutual orchestrated inter-organelle communication: A pleiotropic target for combating Alzheimer's disease

Dysfunctional intraneuronal organelles in Alzheimer's Disease (AD) propel aberrant calcium handling, triggering molecular miscommunication within organelles such as mitochondria, endoplasmic reticulum, and lysosomes. This disruption in organelle function not only impairs cellular homeostasis but also exacerbates neurodegenerative processes involving the accumulation of amyloid-β (Aβ) and hyperphosphorylated tau, amplifying the disease's vicious cycle. In this review, the concept of Mutual Orchestrated Inter-organelle Communication (MOIC) proposes potential therapeutic avenues for restoring Ca2+ homeostasis in AD, offering a theoretical framework for developing disease-modifying treatments. The intricate nature of AD necessitates a shift towards combination therapies targeting MOIC-associated pathways, presenting a more effective approach than monotherapy.

Semaglutide promotes the transition of microglia from M1 to M2 type to reduce brain inflammation in APP/PS1/tau mice

A growing number of studies show that the diabetes drug Semaglutide is neuroprotective in Alzheimer's disease (AD) animal models, but its mode of action is not fully understood. In order to explore the mechanism of Semaglutide, 7-month-old APP/PS1/tau transgenic (3xTg) mice and wild-type (WT) mice were randomly divided into four groups: control group (WT + PBS), AD model group (3xTg + PBS), Semaglutide control group (WT + Semaglutide) and Semaglutide treatment group (3xTg + Semaglutide). Semaglutide (25 nmol/kg) or PBS was administered intraperitoneally once every two days for 30 days, followed by behavioral and molecular experiments. The results show that Semaglutide can improve working memory and spatial reference memory of 3xTg-AD mice, promote the release of anti-inflammatory factors and inhibit the production of pro-inflammatory factors in the cortex and hippocampus, and reduce Aβ deposition in the hippocampal CA1 region of 3xTg mice. Semaglutide can inhibit the apoptosis of BV2 cells induced by Aβ1-42 in a dose-dependent manner and promote the transformation of microglia from M1 to M2, thereby exerting anti-inflammatory and neuroprotective effects. Therefore, we speculate that Semaglutide shows an anti-inflammatory effect by promoting the transformation of microglia from M1 to M2 type in the brain of 3xTg mice, and thus exerts a neuroprotective effect.

Protective effects of L-carnitine against beta-amyloid-induced memory impairment and anxiety-like behavior in a rat model of Alzheimer's disease

Alzheimer's disease (AD), the most common cause of dementia, leads to neurodegeneration and cognitive decline. We investigated the therapeutic effects of L-carnitine on cognitive performance and anxiety-like behavior in a rat model of AD induced by unilateral intracerebroventricular injection of β-amyloid1-42 (Aβ1-42). L-carnitine (100 mg/kg/day) was administered intraperitoneally for 28 consecutive days. Following this, the open-field test, novel object recognition test, elevated plus-maze test, Barnes maze test, and passive avoidance learning test were used to assess locomotor activity, recognition memory, anxiety-like behavior, spatial memory, and passive avoidance memory, respectively. Plasma and hippocampal oxidative stress markers, including total oxidant status (TOS) and total antioxidant capacity (TAC), were examined. In addition, histological investigations were performed in the dentate gyrus of the hippocampus using Congo red staining and hematoxylin and eosin staining. The injection of Aβ1-42 resulted in cognitive deficits and increased anxiety-like behavior. These changes were associated with an imbalance of oxidants and antioxidants in plasma and the hippocampus. Also, neuronal death and Aβ plaque accumulation were increased in the hippocampal dentate gyrus region. However, injection of L-carnitine improved recognition memory, spatial memory, and passive avoidance memory in AD rats. These findings provide evidence that L-carnitine may alleviate anxiety-like behavior and cognitive deficits induced by Aβ1-42 through modulating oxidative-antioxidant status and preventing Aβ plaque accumulation and neuronal death.

Multi Targeted Therapy for Alzheimer's Disease by Guanidinium-Modified Calixarene and Cyclodextrin Co-Assembly Loaded with Insulin

Amyloid-β (Aβ) is considered a primary therapeutic target for Alzheimer's disease (AD). However, just eliminating Aβ in patients with AD has exhibited restricted clinical efficacy, possibly failing to address the metabolic abnormalities caused by AD, such as insulin resistance. To address this concern, our research has employed two types of macrocyclic amphiphiles, guanidinium-modified calixarene and cyclodextrin coassembly (GCD), as delivery systems for insulin. This approach aimed to tackle the metabolic dysregulation characteristic of AD in an innovative manner by exploring beyond the conventional strategy of Aβ removal. As a result, GCD and insulin coassembly could effectively improve plaque deposition and insulin resistance. The coassembly could also reduce abnormal neuronal apoptosis and synaptic damage and improve cognitive impairment in 5xFAD mice. Therefore, the GCD and insulin coassembly shows promise as a viable therapeutic option for AD.

Microbiota-derived lysophosphatidylcholine alleviates Alzheimer's disease pathology via suppressing ferroptosis

Alzheimer's disease (AD) is a pervasive neurodegenerative disorder, and new approaches for its prevention and therapy are critically needed. Here, we elucidate a gut-microbiome-brain axis that offers actionable perspectives for achieving this objective. Using the 5xFAD mouse model, we identify increased Clostridium abundance and decreased Bacteroides abundance as key features associated with β-amyloid (Aβ) burden. Treatment with Bacteroides ovatus, or its associated metabolite lysophosphatidylcholine (LPC), significantly reduces Aβ load and ameliorates cognitive impairment. Mechanistically, LPC acts through the orphan receptor GPR119, inhibiting ACSL4 expression, thereby suppressing ferroptosis and ameliorating AD pathologies. Analysis of fecal and serum samples from individuals with AD also reveals diminished levels of Bacteroides and LPC. This study thus identifies a B.ovatus-triggered pathway regulating AD pathologies and indicates that the use of single gut microbiota, metabolite, or small molecule compound may complement current prevention and treatment approaches for AD.

Structural and functional remodeling of neural networks in β-amyloid driven hippocampal hyperactivity

Early detection of Alzheimer's disease (AD) is essential for improving the patients outcomes and advancing our understanding of disease, allowing for timely intervention and treatment. However, accurate biomarkers are still lacking. Recent evidence indicates that hippocampal hyperexcitability precedes the diagnosis of AD decades ago, can predict cognitive decline. Thus, could hippocampal hyperactivity be a robust biomarker for early-AD, and what drives hippocampal hyperactivity in early-AD? these critical questions remain to be answered. Increasing clinical and experimental studies suggest that early hippocampal activation is closely associated with longitudinal β-amyloid (Aβ) accumulation, Aβ aggregates, in turn, enhances hippocampal activity. Therefore, in this narrative review, we discuss the role of Aβ-induced altered intrinsic neuronal properties as well as structural and functional remodeling of glutamatergic, GABAergic, cholinergic, noradrenergic, serotonergic circuits in hippocampal hyperactivity. In addition, we analyze the available therapies and trials that can potentially be used clinically to attenuate hippocampal hyperexcitability in AD. Overall, the present review sheds lights on the mechanism behind Aβ-induced hippocampal hyperactivity, and highlights that hippocampal hyperactivity could be a robust biomarker and therapeutic target in prodromal AD.

Serum Lipoprotein Profiling by NMR Spectroscopy Reveals Alterations in HDL-1 and HDL-2 Apo-A2 Subfractions in Alzheimer's Disease

Identifying biomarkers for Alzheimer's disease (AD) is crucial, due to its complex pathology, which involves dysfunction in lipid transport, contributing to neuroinflammation, synaptic loss, and impaired amyloid-β clearance. Nuclear magnetic resonance (NMR) is able to quantify and stratify lipoproteins. The study investigated lipoproteins in blood from AD patients, aiming to evaluate their diagnostic potential. Serum and plasma were collected from AD patients (n = 25) and healthy individuals (n = 25). We conducted a comprehensive lipoprotein profiling on serum samples using NMR spectroscopy, analysing 112 lipoprotein subfractions. In plasma, we measured unspecific markers of neuronal damage and AD hallmark proteins using single molecule array technology. Additionally, clinical data and cerebrospinal fluid biomarker levels were also collected to enrich our data. Our findings, after adjusting for age and sex differences, highlight significant alterations in two specific lipoproteins; high-density lipoprotein (HDL)-1 Apo-A2 (H1A2) and HDL-2 Apo-A2 (H2A2), both with area under the curve (AUC) values of 0.67, 95% confidence interval (CI) = 0.52-0.82). These results indicate that these lipoprotein subfractions may have potential as indicators of AD-related metabolic changes.

From Plaques to Pathways in Alzheimer's Disease: The Mitochondrial-Neurovascular-Metabolic Hypothesis

Alzheimer's disease (AD) presents a public health challenge due to its progressive neurodegeneration, cognitive decline, and memory loss. The amyloid cascade hypothesis, which postulates that the accumulation of amyloid-beta (Aβ) peptides initiates a cascade leading to AD, has dominated research and therapeutic strategies. The failure of recent Aβ-targeted therapies to yield conclusive benefits necessitates further exploration of AD pathology. This review proposes the Mitochondrial-Neurovascular-Metabolic (MNM) hypothesis, which integrates mitochondrial dysfunction, impaired neurovascular regulation, and systemic metabolic disturbances as interrelated contributors to AD pathogenesis. Mitochondrial dysfunction, a hallmark of AD, leads to oxidative stress and bioenergetic failure. Concurrently, the breakdown of the blood-brain barrier (BBB) and impaired cerebral blood flow, which characterize neurovascular dysregulation, accelerate neurodegeneration. Metabolic disturbances such as glucose hypometabolism and insulin resistance further impair neuronal function and survival. This hypothesis highlights the interconnectedness of these pathways and suggests that therapeutic strategies targeting mitochondrial health, neurovascular integrity, and metabolic regulation may offer more effective interventions. The MNM hypothesis addresses these multifaceted aspects of AD, providing a comprehensive framework for understanding disease progression and developing novel therapeutic approaches. This approach paves the way for developing innovative therapeutic strategies that could significantly improve outcomes for millions affected worldwide.

Recent Advances in Therapeutics for the Treatment of Alzheimer's Disease

The most prevalent chronic neurodegenerative illness in the world is Alzheimer's disease (AD). It results in mental symptoms including behavioral abnormalities and cognitive impairment, which have a substantial financial and psychological impact on the relatives of the patients. The review discusses various pathophysiological mechanisms contributing to AD, including amyloid beta, tau protein, inflammation, and other factors, while emphasizing the need for effective disease-modifying therapeutics that alter disease progression rather than merely alleviating symptoms. This review mainly covers medications that are now being studied in clinical trials or recently approved by the FDA that fall under the disease-modifying treatment (DMT) category, which alters the progression of the disease by targeting underlying biological mechanisms rather than merely alleviating symptoms. DMTs focus on improving patient outcomes by slowing cognitive decline, enhancing neuroprotection, and supporting neurogenesis. Additionally, the review covers amyloid-targeting therapies, tau-targeting therapies, neuroprotective therapies, and others. This evaluation specifically looked at studies on FDA-approved novel DMTs in Phase II or III development that were carried out between 2021 and 2024. A thorough review of the US government database identified clinical trials of biologics and small molecule drugs for 14 agents in Phase I, 34 in Phase II, and 11 in Phase III that might be completed by 2028.

Thyroid Hormone Supplementation Restores Cognitive Deficit, Insulin Signaling, and Neuroinflammation in the Hippocampus of a Sporadic Alzheimer's-like Disease Rat Model

Thyroid hormones play a crucial role in the development of the central nervous system and are considered pivotal to cognitive functions in the adult brain. Recently, thyroid dysfunction has been associated with Alzheimer's disease. The aim of this study was to assess the neuroprotective effects of triiodothyronine (T3) on insulin signaling, neuroinflammation, apoptosis, and cognitive function in a streptozotocin (STZ)-induced sporadic Alzheimer's disease-like model. Male Wistar rats underwent stereotaxic surgery for intracerebroventricular injections of streptozotocin (STZ; 2 mg/kg) or vehicle in the lateral ventricles to induce an AD-like model. The animals received a daily dose of 1.5 μg of T3/100 g body weight or the same volume of vehicle for 30 days and were subdivided into four experimental groups: (1) animals receiving citrate treated with saline (Control = CTL); (2) animals receiving citrate treated with T3 (T3); (3) animals receiving STZ treated with saline (STZ); and (4) animals receiving STZ treated with T3 (STZ + T3). The novel object recognition test was used to measure cognitive function. Serum analysis, real-time RT-PCR, immunohistochemistry, and immunoblotting analyses were also carried out. Our results demonstrated that T3 treatment reversed cognitive impairment and increased Akt and GSK3 phosphorylation in the treated group, while also reducing microglial activation (Iba-1) and GFAP expression (reactive astrocytes), along with TNF-α, IL-6, and IL-1β levels in the hippocampus. Additionally, T3 treatment increased levels of the anti-apoptotic protein Bcl-2 and reduced the expression of the pro-apoptotic protein BAX in the hippocampus. Our study demonstrated that T3 could potentially protect neurons in an AD model induced by STZ.

ABTrans: A Transformer-based Model for Predicting Interaction between Anti-Aβ Antibodies and Peptides

Antibodies against Aβ peptide have been recently approved to treat Alzheimer's disease, underscoring the importance of understanding their interactions for developing more potent treatments. Here we investigated the interaction between anti-Aβ antibodies and various peptides using a deep learning model. Our model, ABTrans, was trained on dodecapeptide sequences from phage display experiments and known anti-Aβ antibody sequences sourced from public sources. It classified the binding ability between anti-Aβ antibodies and dodecapeptides into four levels: not binding, weak binding, medium binding, and strong binding, achieving an accuracy of 0.83. Using ABTrans, we examined the cross-reaction of anti-Aβ antibodies with other human amyloidogenic proteins, revealing that Aducanumab and Donanemab exhibited the least cross-reactivity. Additionally, we systematically screened interactions between eleven selected anti-Aβ antibodies and all human proteins to identify potential off-target candidates.

Critical assessment of anti-amyloid-β monoclonal antibodies effects in Alzheimer's disease: a systematic review and meta-analysis highlighting target engagement and clinical meaningfulness

Despite most monoclonal antibodies against Aβ in Alzheimer's failed to demonstrate efficacy, the newest antibodies showed statistically significant clinical effects. We conducted a systematic review and meta-analysis to assess the efficacy, target engagement, and safety of anti-Aβ antibodies in sporadic AD including phase III RCTs published up to November 28, 2023. Antibodies as a drug class, attenuated worsening on the clinical scales CDR-SB and ADAS-Cog by very small effect sizes and reduced amyloid on PET by a very large effect size. Reduction of amyloid on PET was moderately correlated with CDR-SB and ADAS-Cog reductions. However, antibodies increased risk of ARIA-E and ARIA-H by a very large and moderate effect size, respectively. In subgroup analyses by individual drug, Donanemab and Lecanemab induced the largest benefits. In subgroup analyses by binding affinity, antibodies without binding to monomers were associated with the most favorable effects. Despite statistical significance for improvement on clinical measures, antibody effects were below the threshold of clinically meaningful change during the period they were studied. However, the newest antibodies demonstrably interfere with the underlying ΑD pathophysiology and therefore their benefit could be cumulative over time leading to larger clinical effects in subsequent years. PROSPERO registration no. CRD42022381334.

Identification of tauopathy-associated lipid signatures in Alzheimer's disease mouse brain using label-free chemical imaging

There is cumulative evidence that lipid metabolism plays a key role in the pathogenesis of various neurodegenerative disorders including Alzheimer's disease (AD). Visualising lipid content in a non-destructive label-free manner can aid in elucidating the AD phenotypes towards a better understanding of the disease. In this study, we combined multiple optical molecular-specific methods, Fourier transform infrared (FTIR) spectroscopic imaging, synchrotron radiation-infrared (SR-IR) microscopy, Raman and stimulated Raman scattering (SRS) microscopy, and optical-photothermal infrared (O-PTIR) microscopy with multivariate data analysis, to investigate the biochemistry of brain hippocampus in situ using a mouse model of tauopathy (rTg4510). We observed a significant difference in the morphology and lipid content between transgenic (TG) and wild type (WT) samples. Immunohistochemical staining revealed some degree of microglia co-localisation with elevated lipids in the brain. These results provide new evidence of tauopathy-related dysfunction in a preclinical study at a subcellular level.

The Relationship Between Alzheimer's Disease and Pyroptosis and the Intervention Progress of Traditional Chinese Medicine

Alzheimer's disease (AD) is a progressive neurodegenerative disease caused by multiple causes. The main pathological features of AD are β-amyloid (Aβ) deposition, hyperphosphorylation of Tau protein, and progressive neuronal loss. Pyroptosis is one of the main forms of neuronal death, which is mainly caused by the activation of Gasdermin protein by upstream signals and the release of its N-terminal domain on the cell membrane. Studies have shown that there is a close relationship between Alzheimer's disease (AD) and pyroptosis. Therefore, this paper summarizes the relationship between pyroptosis and its molecular mechanism and AD, as well as the related research of traditional Chinese medicine in the treatment of AD by regulating pyroptosis, in order to provide a new direction for the study of AD pathogenesis based on pyroptosis pathway.

Safety, tolerability, pharmacokinetics and pharmacodynamics of a single intravenous dose of SHR-1707 in healthy adult subjects: two randomized, double-blind, single-ascending-dose, phase 1 studies

BACKGROUND

SHR-1707 is a novel humanized anti-Aβ IgG1 monoclonal antibody that binds to Aβ fibrils and monomers to block the formation of Aβ plaques or to promote the microglial phagocytosis of Aβ. Preclinical studies showed that SHR-1707 reduced brain Aβ deposition in 5xFAD transgenic mice. Herein, we conducted two phase 1 studies to evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of a single intravenous dose of SHR-1707 in healthy adult subjects.

METHODS

Two randomized, double-blind, single-ascending-dose, phase 1 studies were conducted in China (Study CHN) and Australia (Study AUS). Study CHN consisted of 2 parts. In Part 1, eligible healthy young adults (18-45 years) were sequentially randomized 8:2 to receive SHR-1707 (five cohorts: 2, 6, 20, 40, and 60 mg/kg) or placebo in each cohort; in Part 2, elderly subjects (55-80 years) were randomized 8:4 to receive SHR-1707 (20 mg/kg) or placebo. A similar design was used in Study AUS, but with only healthy young adults enrolled across three dosing cohorts (2, 20, and 60 mg/kg).

RESULTS

Sixty-two (part 1/2, n = 50/12; age range, 18-42/55-63 years) and 30 subjects (age range, 18-42 years) received SHR-1707 or placebo in Study CHN and Study AUS, respectively. In Study CHN, all treatment-related adverse events (TRAEs) were mild, with the most common being transient laboratory abnormalities. In Study AUS, TRAEs were mostly mild (1 moderate event each with SHR-1707/placebo); the most common TRAEs with SHR-1707 were dysgeusia and fatigue (8.3% each). In both studies, the exposure of SHR-1707 increased in a slightly greater than dose-proportional manner over the dose range of 2-60 mg/kg in young adults; there was a dose-dependent increase in plasma Aβ42 concentration following SHR-1707 administration compared with the placebo group. The safety and PK and PD profiles of SHR-1707 in the elderly subjects were consistent with the younger counterpart at the same dose level. No ethnic difference in safety, PK and PD of SHR-1707 was observed.

CONCLUSIONS

A single intravenous dose of SHR-1707 at 2-60 mg/kg was safe and well tolerated in healthy young adult and elderly subjects. The PK and PD profiles are supportive for further clinical development.

TRIAL REGISTRATION

NCT04973189 (retrospectively registered on Jul.21, 2021) and NCT04745104 (registered on Feb.6, 2021) on clinicaltrials.gov.

Hiding in plain sight: Do recruited dendritic cells surround amyloid plaques in Alzheimer's disease?

Over the past decade, human genome-wide association and expression studies have strongly implicated dysregulation of the innate immune system in the pathogenesis of Alzheimer's disease (AD). Single cell mRNA sequencing studies have identified innate immune cell subtypes that are minimally present in normal healthy brain, but whose numbers greatly increase in association with AD pathology. These AD pathology-associated immune cells are putatively the locus for the immune-related AD risk. While the prevailing view is that these immune cells arise from transformation of resident brain microglia, studies across several decades and using multiple techniques and strategies suggest instead that the pathology-associated immune cells are bone-marrow derived hematopoietic cells that are recruited into brain. We critically review this translational literature, emphasizing the strengths and limitations of techniques used to address recruitment and the experimental designs employed. We conclude that the aggregate evidence points toward recruitment into brain of innate immune cells of the myeloid dendritic cell lineage. Recruitment of dendritic cells and their role in AD pathogenesis has broad implications for our understanding of the etiology and pathobiology of AD that impact the strategies to develop new, immune system-targeted therapeutics for this devastating disease.

4D-QSAR, ADMET properties, and molecular dynamics simulations for designing N-substituted urea/thioureas as human glutaminyl cyclase inhibitors

Human glutaminyl cyclase (hQC) inhibitors have great potential to be used as anti- Alzheimer's disease (AD) agents by reducing the toxic pyroform of β-amyloid in the brains of AD patients. The four-dimensional quantitative structure activity relationship (4D-QSAR) model of N-substituted urea/thioureas was established with satisfying predictive ability and statistical reliability (Q2 = 0.521, R2 = 0.933, R2prep = 0.619). By utilizing the developed 4D-QSAR model, a set of new N-substituted urea/thioureas was designed and evaluated for their Absorption Distribution Metabolism Excretion and Toxicity (ADMET) properties. The results of molecular dynamics (MD) simulations, Principal component analysis (PCA), free energy landscape (FEL), dynamic cross-correlation matrix (DCCM) and molecular mechanics generalized Born Poisson-Boltzmann surface area (MM-PBSA) free energy calculations, revealed that the designed compounds were remained stable in protein binding pocket and compounds b ∼ f (-35.1 to -44.55 kcal/mol) showed higher binding free energy than that of compound 14 (-33.51 kcal/mol). The findings of this work will be a theoretical foundation for further research and experimental validation of urea/thiourea derivatives as hQC inhibitors.

Ovariectomy and High Fat-Sugar-Salt Diet Induced Alzheimer's Disease/Vascular Dementia Features in Mice

While the vast majority of Alzheimer's disease (AD) is non-familial, the animal models of AD that are commonly used for studying disease pathogenesis and development of therapy are mostly of a familial form. We aimed to generate a model reminiscent of the etiologies related to the common late-onset Alzheimer's disease (LOAD) sporadic disease that will recapitulate AD/dementia features. Naïve female mice underwent ovariectomy (OVX) to accelerate aging/menopause and were fed a high fat-sugar-salt diet to expose them to factors associated with increased risk of development of dementia/AD. The OVX mice fed a high fat-sugar-salt diet responded by dysregulation of glucose/insulin, lipid, and liver function homeostasis and increased body weight with slightly increased blood pressure. These mice developed AD-brain pathology (amyloid and tangle pathologies), gliosis (increased burden of astrocytes and activated microglia), impaied blood vessel density and neoangiogenesis, with cognitive impairment. Thus, OVX mice fed on a high fat-sugar-salt diet imitate a non-familial sporadic/environmental form of AD/dementia with vascular damage. This model is reminiscent of the etiologies related to the LOAD sporadic disease that represents a high portion of AD patients, with an added value of presenting concomitantly AD and vascular pathology, which is a common condition in dementia. Our model can, thereby, provide a valuable tool for studying disease pathogenesis and for the development of therapeutic approaches.

Magnetic stirring with iron oxide nanospinners accretes neurotoxic Aβ42 oligomers into phagocytic clearable plaques for Alzheimer's disease treatment

An increasing number of medications have been explored to treat the progressive and irreversible Alzheimer's disease (AD) that stands as the predominant form of dementia among neurodegenerative ailments. However, assertions about toxic side effects of these drugs are a significant hurdle to overcome, calling for drug-free nanotherapeutics. Herein, a new therapeutic strategy devoid of conventional drugs or other cytotoxic species was developed. The constructed superparamagnetic iron oxide nanoparticles (SPIONs) nanospinners can accrete neurotoxic β-amyloid 42 oligomers (oAβ42) into aggregated magnetic plaques (mpAβ) by mechanical rotating force via remote interaction between nanoparticles and the applied magnetic field. While the cellular uptake of mpAβ attained from the magnetic stirring treatment by neuronal cells is severely limited, the facile phagocytic uptake of mpAβ by microglial cells leads to the polarization of the brain macrophages to M2 phenotype and thus the increased anti-inflammatory responses to the treatment. The SPION stirring treatment protects the AD mice from memory deterioration and maintain cognitive ability as evidenced from both nesting and Barnes maze tests. The examination of the oAβ42 injected brain tissues with the stirring treatment showed significant amelioration of functional impairment of neurons, microglia, astrocytes and oligodendrocytes alongside no obvious tissue damage caused by stirring meanwhile complete degradation of SPION was observed at day 7 after the treatment. The in vitro and animal data of this work strongly corroborate that this new modality of undruggable stirring treatment with SPIONs provides a new feasible strategy for developing novel AD treatments.

Lost in translation: Inconvenient truths on the utility of mouse models in Alzheimer's disease research

The recent, controversial approval of antibody-based treatments for Alzheimer's disease (AD) is fueling a heated debate on the molecular determinants of this condition. The discussion should also incorporate a critical revision of the limitations of preclinical mouse models in advancing our understanding of AD. We critically discuss the limitations of animal models, stressing the need for careful consideration of how experiments are designed and results interpreted. We identify the shortcomings of AD models to recapitulate the complexity of the human disease. We dissect these issues at the quantitative, qualitative, temporal, and context-dependent levels. We argue that these models are based on the oversimplistic assumptions proposed by the amyloid cascade hypothesis (ACH) of AD and fail to account for the multifactorial nature of the condition. By shedding light on the constraints of current experimental tools, this review aims to foster the development and implementation of more clinically relevant tools. While we do not rule out a role for preclinical models, we call for alternative approaches to be explored and, most importantly, for a re-evaluation of the ACH.

Therapeutic Efficacy of Extracellular Vesicles Derived from Stem Cell for Alzheimer's Disease: A Meta-Analysis Study

BACKGROUND

Alzheimer's disease (AD) poses a significant public health challenge, increasingly affecting patients' finances, mental health, and functional abilities as the global population ages. Stem cell-derived extracellular vesicles (SC-EVs) have emerged as a promising cell-free therapeutic approach for AD, although their precise mechanisms remain unclear. This meta-analysis aims to evaluate the effectiveness of SC-EVs in treating AD.

METHODS

We systematically searched PubMed, EMBASE, and Web of Science databases up to December 31, 2023, identifying studies investigating SC-EVs therapy in AD rodent models. Outcome measures included Morris water maze and Y maze tests, β-amyloid pathology, and inflammatory markers. Statistical analyses utilized Stata 15.1 and R software.

RESULTS

This meta-analysis of 16 studies (2017-2023, 314 animals) demonstrates significant efficacy of SC-EVs therapy in AD models. Pooled analyses demonstrated that SC-EVs therapy significantly increased the learning function as measured by Morris water maze tests (MWM) by -1.83 (95% CI = -2.51 to -1.15, p < 0.0001), Y maze test by 1.66 (95% CI = 1.03 to 2.28, p < 0.0001), decreased Aβ plaques in the hippocampal by -2.10 (95% CI = -2.96 to -1.23, p < 0.0001), and proinflammatory cytokines Tumor necrosis factor alpha (TNFα) by -2.61 (95% CI = -4.87 to -0.35, p < 0.05), Interleukin-1 beta (IL-1β) by -2.37 (95% CI = -3.68 to -1.05, p < 0.001).

CONCLUSIONS

SC-EVs therapy shows promise in enhancing cognitive function and mitigating AD progression in preclinical models. Future research should focus on standardizing methodologies and comparing SC-EVs isolation techniques and dosing strategies to facilitate clinical translation.

The mechanism and consequences of amyloid-β modulating thiamine pyrophosphokinase-1 expression in microglia

Ample studies attribute cognitive decline in Alzheimer's disease to amyloid-β deposition 1-6 . However, brain amyloid-β accumulation that saturates years before the manifestation of clinical symptoms is dissociated with cognitive decline of the disease 7 . It is unknown how these two processes are mechanistically linked. In this and our accompanied study, we report that thiamine pyrophosphokinase-1 (TPK) deficiency plays essential roles in both processes via distinct mechanisms. Here we describe that diminished microglia Tpk controls the propagation of amyloid-β plaques. In APP/PS1 transgenic mice, microglia showed elevated Tpk expression at 2-month-old, but reduction in a plaque-centric manner at 8-month-old. Interestingly, lipopolysaccharide, but not amyloid-β, induceed Tpk reduction in cultured microglia. Tpk reduction led to microglia dysfunction, showing volatile motility but reduced phagocytosis and weak response to focal tissue injury, with accumulation of intracellular lipid droplets and abnormal mitochrondria. In Alzheimer's disease mice, microglia-specific knockout of Tpk caused diminished plaque coverage, exacerbated plaque burden and synaptic loss. However, increased plaques were not accompanied by the development of neurofibrillary tangles or brain atrophy, in contrast to the phenotype described in our accompanied paper with neuronal Tpk deletion. In conclusion, plaque-induced inflammation reduces Tpk in microglia, selectively exacerbating the spread of amyloid pathology.

Modulation of Amyloid and Tau Aggregation to Alleviate Cognitive Impairment in a Transgenic Mouse Model of Alzheimer's Disease

Aggregation of misfolded amyloid-β (Aβ) and hyperphosphorylated tau proteins to plaques and tangles, respectively, is the major drug target of Alzheimer's disease (AD), as the former is an onset biomarker and the latter is associated with neurodegeneration. Thus, we report a small molecule drug candidate, DN5355, with a dual-targeting function toward aggregates of both Aβ and tau. DN5355 was selected through a series of four screenings assessing 52 chemicals for their functions to inhibit and reverse the aggregation of Aβ and tau by utilizing thioflavin T. When orally administered to AD transgenic mouse model 5XFAD, DN5355 significantly reduced cerebral Aβ plaques and hyperphosphorylated tau tangles. In Y-maze spontaneous alteration and contextual fear conditioning tests, 5XFAD mice showed amelioration of cognitive deficits upon the oral administration of DN5355.

In 2024, the amyloid-cascade-hypothesis still remains a working hypothesis, no less but certainly no more

The amyloid-cascade-hypothesis of the pathogenesis of Alzheimer's disease (AD) was introduced 32 years ago, in 1992. From early on, this clear and straight forward hypothesis received a lot of attention, but also a lot of substantial criticism. Foremost, there have always been massive doubts that a complex age-associated disorder of the most intricate organ of the human body, the brain, can be explained by a linear, one-dimensional cause-and-effect model. The amyloid-cascade defines the generation, aggregation, and deposition of the amyloid beta peptide as the central pathogenic mechanism in AD, as the ultimate trigger of the disease, and, consequently, as the key pharmacological target. Certainly, the original 1992 version of this hypothesis has been refined by various means, and the 'formulating fathers' followed up with a few reappraisals and partly very open reflections in 2002, 2006, 2009, and 2016. However, up until today, for the supporters of this hypothesis, the central and initial steps of the cascade are believed to be driven by amyloid beta-even if now displayed somewhat more elaborate. In light of the recently published clinical results achieved with anti-amyloid antibodies, the controversy in the field about (1) the clinical meaningfulness of this approach, (2) the significance of clearance of the amyloid beta peptide, and last but not least (3) the relevance of the amyloid-cascade-hypothesis is gaining momentum. This review addresses the interesting manifestation of the amyloid-cascade-hypothesis as well as its ups and downs over the decades.

Potential therapeutic natural compounds for the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated neurodegenerative disease with cognitive impairment occurring in the older people, in which extracellular accumulation of β-amyloid and intracellular aggregation of hyperphosphorylated tau are regarded as the prevailing theories. However, the exact AD mechanism has not been determined. Moreover, there is no effective treatment available in phase III trials to eradicate AD, which is imperative to explore novel treatments.

PURPOSE

A number of up-to-date pre-clinical studies on cognitive impairment is beneficial to clarify the pathology of AD. This review recapitulates several advances in AD pathobiology and discusses the neuroprotective effects of natural compounds, such as phenolic compounds, natural polysaccharides and oligosaccharides, peptide, and lipids, underscoring the therapeutic potential for AD.

METHODS

Electronic databases involving PubMed, Web of Science, and Google Scholar were searched up to October 2023. Articles were conducted using the keywords like Alzheimer's disease, pathogenic mechanisms, natural compounds, and neuroprotection.

RESULT

This review summarized several AD pathologies and the neuroprotective effects of natural compounds such as natural polysaccharides and oligosaccharides, peptide, and lipids.

CONCLUSION

We have discussed the pathogenic mechanisms of AD and the effect natural products on neurodegenerative diseases particularly in treating AD. Specifically, we investigated the molecular pathways and links between natural compounds and Alzheimer's disease such as through NF-κB, Nrf2, and mTOR pathway. Further investigation is necessary in exploring the bioactivity and effectiveness of natural compounds in clinical trials, which may provide a promising treatment for AD patients.

The reciprocal relationship between amyloid precursor protein and mitochondrial function

Amyloid precursor protein (APP), secretase enzymes, and amyloid beta (Aβ) have been extensively studied in the context of Alzheimer's disease (AD). Despite this, the function of these proteins and their metabolism is not understood. APP, secretase enzymes, and APP processing products (Aβ and C-terminal fragments) localize to endosomes, mitochondria, endoplasmic reticulum (ER), and mitochondrial/ER contact sites. Studies implicate significant relationships between APP, secretase enzyme function, APP metabolism, and mitochondrial function. Mitochondrial dysfunction is a key pathological hallmark of AD and is intricately linked to proteostasis. Here, we review studies examining potential functions of APP, secretase enzymes, and APP metabolites in the context of mitochondrial function and bioenergetics. We discuss implications and limitations of studies and highlight knowledge gaps that remain in the field.

Alzheimer's disease approaches - Focusing on pathology, biomarkers and clinical trial candidates

The strategy for the development of new drugs for Alzheimer's disease (AD) recognizes that an effective therapy requires early therapeutic intervention and a multifactorial approach that considers the individual initiators of AD development. Current knowledge of AD includes the understanding of pathophysiology, risk factors, biomarkers, and the evolving patterns of biomarker abnormalities. This knowledge is essential in identifying potential molecular targets for new drug development. This review summarizes promising AD drug candidates, many of which are currently in phase 2 or 3 clinical trials. New agents are classified according to the Common Alzheimer's Disease Research Ontology (CADRO). The main targets of new drugs for AD are processes related to amyloid beta and tau neurotoxicity, neurotransmission, inflammation, metabolism and bioenergetics, synaptic plasticity, and oxidative stress. These interventions are aimed at preventing disease onset and slowing or eliminating disease progression. The efficacy of pharmacotherapy may be enhanced by combining these drugs with other treatments, antioxidants, and dietary supplements. Ongoing research into AD pathophysiology, risk factors, biomarkers, and the dynamics of biomarker abnormalities may contribute to the understanding of AD and offer hope for effective therapeutic strategies in the near future.

Biomimetic engineering of a neuroinflammation-targeted MOF nanozyme scaffolded with photo-trigger released CO for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is one of the most fatal and irreversible neurodegenerative diseases, which causes a huge emotional and financial burden on families and society. Despite the progress made with recent clinical use of inhibitors of acetylcholinesterase and amyloid-β (Aβ) antibodies, the curative effects of AD treatment remain unsatisfactory, which is probably due to the complexity of pathogenesis and the multiplicity of therapeutic targets. Thus, modulating complex pathological networks could be an alternative approach to treat AD. Here, a neutrophil membrane-coated MOF nanozyme (denoted as Neu-MOF/Fla) is biomimetically engineered to disturb the malignant Aβ deposition-inflammation cycle and ameliorate the pathological network for effective AD treatment. Neu-MOF/Fla could recognize the pathological inflammatory signals of AD, and deliver the photo-triggered anti-inflammatory CO and MOF based hydrolytic nanozymes to the lesion area of the brain in a spontaneous manner. Based on the in vitro and in vivo studies, Neu-MOF/Fla significantly suppresses neuroinflammation, mitigates the Aβ burden, beneficially modulates the pro-inflammatory microglial phenotypes and improves the cognitive defects of AD mice models. Our work presents a good example for developing biomimetic multifunctional nanotherapeutics against AD by means of amelioration of multiple symptoms and improvement of cognitive defects.

Discovery of novel coumarin triazolyl and phenoxyphenyl triazolyl derivatives targeting amyloid beta aggregation-mediated oxidative stress and neuroinflammation for enhanced neuroprotection

This study involved designing, synthesizing, and evaluating the protective potential of compounds on microglial cells (BV-2 cells) and neurons (SH-SY5Y cells) against cell death induced by Aβ1-42. It aimed to identify biologically specific activities associated with anti-Aβ aggregation and understand their role in oxidative stress initiation and modulation of proinflammatory cytokine expression. Actively designed compounds CE5, CA5, PE5, and PA5 showed protective effects on BV-2 and SH-SY5Y cells, with cell viability ranging from 60.78 ± 2.32% to 75.38 ± 2.75% for BV-2 cells and 87.21% ± 1.76% to 91.55% ± 1.78% for SH-SY5Y cells. The transformation from ester in CE5 to amide in CA5 resulted in significant antioxidant properties. Molecular docking studies revealed strong binding of CE5 to critical Aβ aggregation regions, disrupting both intra- and intermolecular formations. TEM assessment supported CE5's anti-Aβ aggregation efficacy. Structural variations in PE5 and PA5 had diverse effects on IL-1β and IL-6, suggesting further specificity studies for Alzheimer's disease. Log P values suggested potential blood-brain barrier permeation for CE5 and CA5, indicating suitability for CNS drug development. In silico ADMET and toxicological screening revealed that CE5, PA5, and PE5 have favorable safety profiles, while CA5 shows a propensity for hepatotoxicity. According to this prediction, coumarin triazolyl derivatives are likely to exhibit mutagenicity. Nevertheless, CE5 and CA5 emerge as promising lead compounds for Alzheimer's therapeutic intervention, with further insights expected from subsequent in vivo studies.

Revolutionizing Alzheimer's treatment: Harnessing human serum albumin for targeted drug delivery and therapy advancements

Alzheimer's disease (AD) is a neurodegenerative disorder initiated by amyloid-beta (Aβ) accumulation, leading to impaired cognitive function. Several delivery approaches have been improved for AD management. Among them, human serum albumin (HSA) is broadly employed for drug delivery and targeting the Aβ in AD owing to its biocompatibility, Aβ inhibitory effect, and nanoform, which showed blood-brain barrier (BBB) crossing ability via glycoprotein 60 (gp60) receptor and secreted protein acidic and rich in cysteine (SPARC) protein to transfer the drug molecules in the brain. Thus far, there is no previous review focusing on HSA and its drug delivery system in AD. Hence, the reviewed article aimed to critically compile the HSA therapeutic as well as drug delivery role in AD management. It also delivers information on how HSA-incorporated nanoparticles with surfaced embedded ligands such as TAT, GM1, and so on, not only improve BBB permeability but also increase neuron cell targetability in AD brain. Additionally, Aβ and tau pathology, including various metabolic markers likely BACE1 and BACE2, etc., are discussed. Besides, the molecular interaction of HSA with Aβ and its distinctive forms are critically reviewed that HSA can segregate Zn(II) and Cu(II) metal ions from Aβ owing to high affinity. Furthermore, the BBB drug delivery challenges in AD are addressed. Finally, the clinical formulation of HSA for the management of AD is critically discussed on how the HSA inhibits Aβ oligomer and fibril, while glycated HSA participates in amyloid plaque formation, i.e., β-structure sheet formation. This review report provides theoretical background on HSA-based AD drug delivery and makes suggestions for future prospect-related work.

Design of amyloidogenic peptide traps

Segments of proteins with high β-strand propensity can self-associate to form amyloid fibrils implicated in many diseases. We describe a general approach to bind such segments in β-strand and β-hairpin conformations using de novo designed scaffolds that contain deep peptide-binding clefts. The designs bind their cognate peptides in vitro with nanomolar affinities. The crystal structure of a designed protein-peptide complex is close to the design model, and NMR characterization reveals how the peptide-binding cleft is protected in the apo state. We use the approach to design binders to the amyloid-forming proteins transthyretin, tau, serum amyloid A1 and amyloid β1-42 (Aβ42). The Aβ binders block the assembly of Aβ fibrils as effectively as the most potent of the clinically tested antibodies to date and protect cells from toxic Aβ42 species.

Nomination of a novel plasma protein biomarker panel capable of classifying Alzheimer's disease dementia with high accuracy in an African American cohort

Introduction

African Americans (AA) are widely underrepresented in plasma biomarker studies for Alzheimer's disease (AD) and current diagnostic biomarker candidates do not reflect the heterogeneity of AD.

Methods

Untargeted proteome measurements were obtained using the SomaScan 7k platform to identify novel plasma biomarkers for AD in a cohort of AA clinically diagnosed as AD dementia (n=183) or cognitively unimpaired (CU, n=145). Machine learning approaches were implemented to identify the set of plasma proteins that yields the best classification accuracy.

Results

A plasma protein panel achieved an area under the curve (AUC) of 0.91 to classify AD dementia vs CU. The reproducibility of this finding was observed in the ANMerge plasma and AMP-AD Diversity brain datasets (AUC=0.83; AUC=0.94).

Discussion

This study demonstrates the potential of biomarker discovery through untargeted plasma proteomics and machine learning approaches. Our findings also highlight the potential importance of the matrisome and cerebrovascular dysfunction in AD pathophysiology.

Computational identification of potential tau tubulin kinase 1 (TTBK1) inhibitors: a structural analog approach

Abnormal deposition or aggregation of protein alpha-synuclein and tau in the brain leads to neurodegenerative disorders. Excessive hyperphosphorylation of tau protein and aggregations destroys the microtubule structure resulting in neurofibrillary tangles in neurons and affecting cytoskeleton structure, mitochondrial axonal transport, and loss of synapses in neuronal cells. Tau tubulin kinase 1 (TTBK1), a specific neuronal kinase is a potential therapeutic target for neurodegenerative disorders as it is involved in hyperphosphorylation and aggregation of tau protein. TTBK inhibitors are now the subject of intense study, but limited numbers are found. Hence, this study involves structure-based virtual screening of TTBK1 inhibitor analogs to obtain efficient compounds targeting the TTBK1 using docking, molecular dynamics simulation and protein-ligand interaction profile. The initial analogs set containing 3884 compounds was subjected to Lipinski rule and the non-violated compounds were selected. Docking analysis was done on 2772 compounds through Autodock vina and Autodock 4.2. Data Warrior and SwissADME was utilized to filter the toxic compounds. The stability and protein-ligand interaction of the docked complex was analyzed through Gromacs and VMD. Molecular simulation results such as RMSD, Rg, and hydrogen bond interaction along with pharmacokinetic properties showed CID70794974 as the potential hit targeting TTBKl prompting the need for further experimental investigation to evaluate their potential therapeutic efficacy in Alzheimer's disease.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00242-z.