The amyloid hypothesis of Alzheimer's disease at 25 years

Systematic review of amyloid-beta clearance proteins from the brain to the periphery: implications for Alzheimer's disease diagnosis and therapeutic targets

Amyloid-beta clearance plays a key role in the pathogenesis of Alzheimer's disease. However, the variation in functional proteins involved in amyloid-beta clearance and their correlation with amyloid-beta levels remain unclear. In this study, we conducted meta-analyses and a systematic review using studies from the PubMed, Embase, Web of Science, and Cochrane Library databases, including journal articles published from inception to June 30, 2023. The inclusion criteria included studies comparing the levels of functional proteins associated with amyloid-beta clearance in the blood, cerebrospinal fluid, and brain of healthy controls, patients with mild cognitive impairment, and patients with Alzheimer's disease. Additionally, we analyzed the correlation between these functional proteins and amyloid-beta levels in patients with Alzheimer's disease. The methodological quality of the studies was assessed via the Newcastle‒Ottawa Scale. Owing to heterogeneity, we utilized either a fixed-effect or random-effect model to assess the 95% confidence interval (CI) of the standard mean difference (SMD) among healthy controls, patients with mild cognitive impairment, and patients with Alzheimer's disease. The findings revealed significant alterations in the levels of insulin-degrading enzymes, neprilysin, matrix metalloproteinase-9, cathepsin D, receptor for advanced glycation end products, and P-glycoprotein in the brains of patients with Alzheimer's disease, patients with mild cognitive impairment, and healthy controls. In cerebrospinal fluid, the levels of triggering receptor expressed on myeloid cells 2 and ubiquitin C-terminal hydrolase L1 are altered, whereas the levels of TREM2, CD40, CD40L, CD14, CD22, cathepsin D, cystatin C, and α2 M in peripheral blood differ. Notably, TREM2 and cathepsin D showed changes in both brain (SMD = 0.31, 95% CI: 0.16-0.47, P < 0.001, I2 = 78.4%; SMD = 1.24, 95% CI: 0.01-2.48, P = 0.048, I2 = 90.1%) and peripheral blood (SMD = 1.01, 95% CI: 0.35-1.66, P = 0.003, I2 = 96.5%; SMD = 7.55, 95% CI: 3.92-11.18, P < 0.001, I2 = 98.2%) samples. Furthermore, correlations were observed between amyloid-beta levels and the levels of TREM2 ( r = 0.16, 95% CI: 0.04-0.28, P = 0.009, I2 = 74.7%), neprilysin ( r = -0.47, 95% CI: -0.80-0.14, P = 0.005, I2 = 76.1%), and P-glycoprotein ( r = -0.31, 95% CI: -0.51-0.11, P = 0.002, I2 = 0.0%) in patients with Alzheimer's disease. These findings suggest that triggering receptor expressed on myeloid cells 2 and cathepsin D could serve as potential diagnostic biomarkers for Alzheimer's disease, whereas triggering receptor expressed on myeloid cells 2, neprilysin, and P-glycoprotein may represent potential therapeutic targets.

Decoding molecular mechanisms: brain aging and Alzheimer's disease

The complex morphological, anatomical, physiological, and chemical mechanisms within the aging brain have been the hot topic of research for centuries. The aging process alters the brain structure that affects functions and cognitions, but the worsening of such processes contributes to the pathogenesis of neurodegenerative disorders, such as Alzheimer's disease. Beyond these observable, mild morphological shifts, significant functional modifications in neurotransmission and neuronal activity critically influence the aging brain. Understanding these changes is important for maintaining cognitive health, especially given the increasing prevalence of age-related conditions that affect cognition. This review aims to explore the age-induced changes in brain plasticity and molecular processes, differentiating normal aging from the pathogenesis of Alzheimer's disease, thereby providing insights into predicting the risk of dementia, particularly Alzheimer's disease.

Phytocompounds of Senecio candicans as potential acetylcholinesterase inhibitors targeting Alzheimer's disease: A structure-based virtual screening and molecular dynamics simulation study

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by cognitive decline due to the accumulation of amyloid-beta plaques, neurofibrillary tangles, and decreased acetylcholine levels caused by acetylcholinesterase (AChE) activity. Current treatments using synthetic acetylcholinesterase inhibitors (AChEIs) provide only symptomatic relief and are associated with adverse effects, highlighting the need for safer and more effective alternatives. This study investigates the potential of phytoconstituents from the plant Senecio candicans as natural AChE inhibitors for AD treatment. Using structure-based virtual screening, molecular docking, and molecular dynamics simulations, we evaluated several compounds from Senecio candicans for their binding affinity, stability, and inhibitory activity against AChE. The findings identified compounds such as Estra-135(10)-trien-17β-ol and Vulgarone A, which demonstrated strong binding affinities and stable interactions with AChE, comparable to or surpassing the clinically used drug Donepezil. These phytoconstituents exhibited potential as effective AChEIs with potentially fewer side effects. The results underscore the therapeutic potential of plant-based molecules for drug discovery, offering a promising avenue for developing new treatments for neurodegenerative diseases. Combining phytochemical studies with computational methods provides a powerful approach to identifying novel therapeutic agents. This study suggests that phytoconstituents from Senecio candicans could serve as safer alternatives for managing AD. Further experimental validation and clinical studies are necessary to confirm these compounds' efficacy and safety, paving the way for innovative, plant-derived treatments for Alzheimer's disease.

An approach to predict and inhibit Amyloid Beta dimerization pattern in Alzheimer's disease

Alzheimer's Disease (AD) is one of the leading neurodegenerative diseases that affect the human population. Several hypotheses are in the pipeline to establish the commencement of this disease; however, the amyloid hypothesis is one of the most widely accepted ones. Amyloid plaques are rich in Amyloid Beta (Aβ) proteins, which are found in the brains of Alzheimer's patients. They are the spliced product of a transmembrane protein called Amyloid Precursor Protein (APP); when they enter into the amylogenic pathway, they get cleaved simultaneously by Beta and Gamma Secretase and produce Aβ protein. Appearances of Amyloid plaques are the significant clinical hallmarks of this disease. AD is mainly present in two genetically distinct forms; sporadic and familial AD. Sporadic Alzheimer's Disease (sAD) is marked by a later clinical onset of the disease, whereas, familial Alzheimer's Disease (fAD) is an early onset of the disease with mendelian inheritance. Several mutations have been clinically reported in the last decades that have shown a direct link with fAD. Many of those mutations are reported to be present in the APP. In this study, we selected a few significant mutations present in the Aβ stretch of the APP and tried to differentiate the wild-type Aβ dimers formed in sAD and the mutant dimers formed in fAD through molecular modelling as there are no structures available from wet-lab studies till date. We analysed the binding interactions leading to formations of the dimers. Our next aim was to come up with a solution to treat AD using the method of drug repurposing. For that we used virtual screening and molecular docking simulations of the already existing anti-inflammatory drugs and studied their potency in resisting the formation of Aβ dimers. This is the first such report of drug repurposing for the treatment of AD, which might pave new pathways in therapy.

Lipidopathy disrupts peripheral and central amyloid clearance in Alzheimer's disease: Where are our knowledge

Amyloid-beta (Aβ) production is a normal physiological process, essential for neuronal function. However, an imbalance in Aβ production and clearance is the central pathological feature of Alzheimer's disease (AD), leading to the accumulation of Aβ plaques in the brain. Low-density lipoprotein receptor-related protein 1 (LRP1) plays a critical role in both the central clearance of Aβ from the brain and its peripheral transport to visceral organs. Disruptions in these processes contribute to the accumulation of Aβ in the central nervous system (CNS) and the progression of AD. Recent research emphasizes the need for a broader focus on the systemic effects of organs outside the brain, particularly in the context of AD prevention and treatment. The contribution of peripheral systems, such as the liver, in Aβ clearance, is vital, given that Aβ levels in the plasma correlate closely with those in the brain. Consequently, targeting systemic processes, rather than focusing solely on the CNS, may offer promising therapeutic approaches. Furthermore, high-density lipoprotein (HDL) facilitates the formation of lipoprotein-amyloid complexes, which are important for Aβ transport and clearance, using proteins such as apolipoproteins E and J (ApoE and ApoJ) to form complexes that help manage Aβ accumulation. On the other hand, low-density lipoprotein (LDL) facilitates Aβ efflux from the brain by binding to LRP1, promoting its clearance. Given the relationship between lipid profiles and Aβ levels, along with lipid-modifying drugs, may be effective in managing Aβ accumulation and mitigating AD progression.

Amyloid β fragments that suppress oligomers but not fibrils are cytoprotective

Neurotoxic aggregates of amyloid beta (Aβ) peptide contribute to the etiology of Alzheimer's disease (AD). In this work, we examined how seven overlapping fragments derived from Aβ1-42 affect the oligomerization and toxicity of the full-length peptide. Four fragments inhibited the toxicity of oligomeric Aβ1-42 to various degrees, two others conferred no cellular protection against Aβ1-42 toxicity, and one fragment enhanced both Aβ1-42 oligomerization and toxicity. The structural and aggregation propensities of the peptides that support strong inhibition of Aβ1-42 toxicity have been identified. Data analysis allowed elucidation of the mechanisms of action of each of the seven peptide fragments on Aβ1-42 cytotoxicity. Our work establishes the potential therapeutic value of four Aβ fragments and supports the notion that agents directed to disruption of Aβ oligomers may be more effective AD drug candidates than those targeting Aβ fibrils.

Comparing levetiracetam and zonisamide effects on rivastigmine anti-Alzheimer's activity in aluminum chloride-induced Alzheimer's-like disease in rats: Impact on α7 nicotinic acetylcholine receptors and amyloid β

BACKGROUND AND AIM

Alzheimer's disease (AD) is the most progressive form of neurodegenerative disease, which severely impairs cognitive function. The leading class of drugs used to treat AD is acetylcholinesterase inhibitors (AChE-Is) as Rivastigmine (RIVA), partially ameliorate its cognitive symptoms. Since epilepsy is a common comorbidity with AD, we explored the potential that new the antiepileptic drugs; Levetiracetam (LEV) and Zonisamide (ZNS) may possess an additional therapeutic benefit to RIVA in AlCl3-induced AD rat model.

MATERIALS AND METHODS

AlCl3 was used to provoke AD in rats which were then supplemented with treatment drugs for 2 weeks. Treated groups were: Control, AlCl3, RIVA, LEV, RIVA + LEV, ZNS and RIVA + ZNS. Then, the behavioral tests; passive avoidance (PA), Morris water maze (MWM) and novel object recognition (NOR) were conducted to assess cognitive behavior and memory. The Hippocampal Aβ assembly was thoroughly examined by histopathology and ELISA. α7 Nicotinic ACh receptors' (α7nAChRs) expression was assessed immunohistochemically and by real-time quantitative polymerase chain reaction (qPCR). Caspase 3 expression was also assessed by real-time qPCR in hippocampal tissues.

RESULTS

AlCl3 administration impaired memory and cognitive functions in rats, augmented hippocampal Aβ deposition, with subsequent neurodegeneration and α7nAChRs down-regulation. LEV, but not ZNS, administration significantly mitigated AlCl3-induced cognitive impairment probably through suppression of amyloid β (Aβ) deposition, enhancement of neurogenesis and α7nAChRs expression. When combined to RIVA, ZNS treatment negatively affected cognition possibly through its impact on hippocampal Aβ and subsequent neuronal damage.

CONCLUSION

Although our results indicated that neither LEV nor ZNS provided any extra benefit to cognitive enhancements in AD rats receiving rivastigmine, LEV demonstrated positive effects individually while ZNS had negative effects when combined with RIVA. As a result, this study suggests the use of LEV rather than ZNS for managing epilepsy in patients with AD given that Alzheimer's and epilepsy can coexist.

Refining the interactions between microglia and astrocytes in Alzheimer's disease pathology

Microglia and astrocytes are central to the pathogenesis and progression of Alzheimer's Disease (AD), working both independently and collaboratively to regulate key pathological processes such as β-amyloid protein (Aβ) deposition, tau aggregation, neuroinflammation, and synapse loss. These glial cells interact through complex molecular pathways, including IL-3/IL-3Ra and C3/C3aR, which influence disease progression and cognitive decline. Emerging research suggests that modulating these pathways could offer therapeutic benefits. For instance, recombinant IL-3 administration in mice reduced Aβ plaques and improved cognitive functions, while C3aR inhibition alleviated Aβ and tau pathologies, restored synaptic function, and corrected immune dysregulation. However, the effects of these interactions are context-dependent. Acute C3/C3aR activation enhances microglial Aβ clearance, whereas chronic activation impairs it, highlighting the dual roles of glial signaling in AD. Furthermore, C3/C3aR signaling not only impacts Aβ clearance but also modulates tau pathology and synaptic integrity. Given AD's multifactorial nature, understanding the specific pathological environment is crucial when investigating glial cell contributions. The interplay between microglia and astrocytes can be both neuroprotective and neurotoxic, depending on the disease stage and brain region. This complexity underscores the need for targeted therapies that modulate glial cell activity in a context-specific manner. By elucidating the molecular mechanisms underlying microglia-astrocyte interactions, this research advances our understanding of AD and paves the way for novel therapeutic strategies aimed at mitigating neurodegeneration and cognitive decline in AD and related disorders.

A Ginsenoside Composition Ameliorated Aβ and Tau Aggregation via Autophagy Lysosome Pathway

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by the abnormal deposition of amyloid-beta (Aβ) peptides and neurofibrillary tangles (NFTs). Ginsenosides, the primary active constituents in ginseng, exhibit potential in combating AD. In our previous work, the ginsenoside SumI was demonstrated to have superior anti-AD activity compared to other ginsenosides when used alone. This study revealed that SumI effectively decreased the lysosomal pH, promoted autophagosome formation, increased autophagic flux, and facilitated the transport of misfolded proteins to lysosomes for degradation in Caenorhabditis elegans. SumI activated the HLH-30 transcription factor by triggering a lipid-catabolic response akin to starvation. bec-1 RNAi significantly abrogated the anti-AD effect of SumI. Our findings indicate that SumI mitigated protein aggregation by activating the autophagy-lysosome pathway in C. elegans and provide scientific evidence that ginsenoside composition could be a potential therapeutic agent for treating or preventing AD.

Advancements in Stem Cell Research for Effective Therapies Against Alzheimer's Disease: Current Investigation and Future Insight

Alzheimer's disease (AD) is the most prevalent cause of dementia in the elderly, affecting approximately 50 million individuals globally with significant impose in health and financial burdens. Despite extensive research, no current treatment effectively halts the progression of AD, primarily due to its complex pathophysiology of the disease and the limitations of available therapeutic approaches. In this context, stem cell transplantation has emerged as a promising treatment strategy, harnessing the regenerative capabilities of various stem cell types, including neural stem cells (NSCs), embryonic stem cells (ESCs), and mesenchymal stem cells (MSCs). This review explores the potential of stem cell-based therapies in AD, emphasizing the necessity for continued innovation to overcome existing challenges and enhance therapeutic efficacy. Briefly, NSCs have shown potential in improving cognitive function and reducing AD pathology through targeted transplantation and neuroprotection; however, challenges such as optimizing transplantation protocols and ensuring effective cell integration persist. Concurrently, ESCs, with their pluripotent nature, present opportunities for modulating AD and generating therapeutic neurons, but ethical concerns and immunogenicity present significant obstacles to clinical application. Moreover, MSCs have demonstrated potential in ameliorating AD-related pathology and promoting neurogenesis, offering a more accessible alternative with fewer ethical constraints. The review concludes that the combinatory approaches of different stem cells may provide synergistic benefits in addressing AD-related pathophysiology, warranting further exploration in future research.

Hyperphosphorylated tau-based Alzheimer's Disease drug discovery: Identification of inhibitors of tau aggregation and cytotoxicity

Alzheimer's disease (AD) is a neurodegenerative disorder that affects more than 30 million people worldwide. Underlying the progressive decline of cognitive functions are the neurofibrillary tangles (NFTs) in neurons of the brain. The spatiotemporal distribution of NFTs predicts the progression of cognitive symptoms. In contrast, the senile plaques of amyloid-β aggregates, another major biomarker for AD, do not correlate with the clinical symptom development, consistent with the negligible benefits to cognitive functions in patients receiving anti-Aβ immunotherapies. A new drug discovery avenue targeting tau pathologies is therefore urgently needed. Using a recombinant hyperphosphorylated tau (p-tau) that presents characters key to the disease, e.g., formation of neurotoxic aggregates, we conducted a fluorescence p-tau aggregation assay and completed a 100K-compound high-throughput screen (HTS) and identified inhibitors of p-tau aggregation and cytotoxicity. This dual functional screen resulted in several potent compounds that effectively curbed both p-tau aggregation and cytotoxicity. Results presented in this work are the first HTS for small-molecule compounds that target the cellular toxicity of hyperphosphorylated tau. Top hits found in this screen and their analogues to be developed in the near future may lead to breakthroughs in the therapeutic development for Alzheimer's disease and other neurodegenerative tauopathies.

The thermodynamic hypothesis of protein aggregation

Protein misfolding and aggregation drive some of the most prevalent and lethal disorders of our time, including Alzheimer's and Parkinson's diseases, now affecting tens of millions of people worldwide. The complexity of these diseases, which are often multifactorial and related to age and lifestyle, has made it challenging to identify the causes of the accumulation of aberrant protein deposits. An insight into the origins of these deposits comes from reports of a widespread presence of protein aggregates even under normal cellular conditions. This observation is best accounted for by the thermodynamic hypothesis of protein aggregation. According to this hypothesis, many proteins are expressed at levels close to their supersaturation limits, so that their native states are metastable against aggregation. Here we integrate the evidence behind this hypothesis and outline actionable therapeutic strategies that could halt protein aggregation at its source.

Knowing the enemy: strategic targeting of complement to treat Alzheimer disease

The complement system protects against infection, positively responds to tissue damage, clears cell debris, directs and modulates the adaptive immune system, and functions in neuronal development, normal synapse elimination and intracellular metabolism. However, complement also has a role in aberrant synaptic pruning and neuroinflammation - processes that lead to a feedforward loop of inflammation, injury and neuronal death that can contribute to neurodegenerative and neurological disorders, including Alzheimer disease. This Review provides justification, largely from preclinical mouse models but also from correlates with human tissue and biomarkers, for targeting specific complement components for therapeutic intervention in Alzheimer disease. We discuss promising strategies to slow the progression of cognitive loss with minimal undesired effects. The diverse interactions and functions of complement system components can influence biological processes in the healthy and diseased brain; here, these functions are described as a prerequisite to selecting appropriate, safe and effective therapeutic targets for translation to the clinic.

Effects of sleep on the glymphatic functioning and multimodal human brain network affecting memory in older adults

Understanding how sleep affects the glymphatic system and human brain networks is crucial for elucidating the neurophysiological mechanism underpinning aging-related memory declines. We analyzed a multimodal dataset collected through magnetic resonance imaging (MRI) and polysomnographic recording from 72 older adults. A proxy of the glymphatic functioning was obtained from the Diffusion Tensor Image Analysis along the Perivascular Space (DTI-ALPS) index. Structural and functional brain networks were constructed based on MRI data, and coupling between the two networks (SC-FC coupling) was also calculated. Correlation analyses revealed that DTI-ALPS was negatively correlated with sleep quality measures [e.g., Pittsburgh Sleep Quality Index (PSQI) and apnea-hypopnea index]. Regarding human brain networks, DTI-ALPS was associated with the strength of both functional connectivity (FC) and structural connectivity (SC) involving regions such as the middle temporal gyrus and parahippocampal gyrus, as well as with the SC-FC coupling of rich-club connections. Furthermore, we found that DTI-ALPS positively mediated the association between sleep quality and rich-club SC-FC coupling. The rich-club SC-FC coupling further mediated the association between DTI-ALPS and memory function in good sleepers but not in poor sleepers. The results suggest a disrupted glymphatic-brain relationship in poor sleepers, which underlies memory decline. Our findings add important evidence that sleep quality affects cognitive health through the underlying neural relationships and the interplay between the glymphatic system and multimodal brain networks.

The reverse sequence of Aβ amyloid self-triggers isolated nano-fibers and oligomers in lipid environment

Nanostructured lipid/peptide film at air/water interface allow to build different molecular arrangements depending of peptide sequence, peptide proportion and type of lipid. We studied the surface properties of Aβ(1 -42) and its retro-isomer Aβ(42 -1) amyloid peptides mixed with 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) lipid at the air/water interface. In absence of lipids, pure form of both Aβ(1 -42) and Aβ(42 -1) form insoluble monolayer films without appreciable fibril-like structures despite the high interfacial confinement. We show the lipid/peptide interfacial organization depends on the reversing sequence peptide in lipid enriched environment. In POPC/Aβ(1 -42) mixed film we have observed network fibril-like structures. However, using Aβ(42 -1) retro-isomer peptide to form the mixed film, the induced structuration acquired an isolated fibers arrangement associated with oligomers. The above structures are clearly visualized at the interface by using Brewster Angle Microscopy. In the same way, the isolate fibers and oligomers become Thioflavin T positive when they are observed by Fluorescence Microscopy. Thus, we attributed an amyloid behavior at the air/water interface that was also evidenced by Scanning Electron Microscopy when the mixed film was transferred to mica support. Changes from an exclusive β-sheet in pure peptide to a notable increase in α-helix/unordered conformations were induced by the presence of the lipid keeping with fibril-like structures. We postulated that the amyloid fibril formation at the membrane interface not only depends on the interfacial lipid environment and the low amyloid peptide content but also by the reversing sequencing that imposed a differential lipid/peptide interaction at the interface. Despite the retro-isomer peptide has not impact nor the overall molecular hydrophobicity neither on the interfacial behavior although perform a "conformational selective process" that depends on the β-sheet and α-helix contents.

PET Imaging of Neurofluids

Following a brief review of brain neurofluid pathways and the general PET technique, we introduce PET imaging of cerebrospinal fluid and interstitial fluid dynamics. Our summary includes both our published and unpublished observations on the modeling of PET imaging for neurofluid quantification in aging, Alzheimer's disease, and in the presence of amyloid lesions. We identify the limitations of PET imaging and point to validations and potential future directions.

Unraveling the mystery of citrate transporters in Alzheimer's disease: An updated review

A key molecule in cellular metabolism, citrate is essential for lipid biosynthesis, energy production, and epigenetic control. The etiology of Alzheimer's disease (AD), a progressive neurodegenerative illness marked by memory loss and cognitive decline, may be linked to dysregulated citrate transport, according to recent research. Citrate transporters, which help citrate flow both inside and outside of cells, are becoming more and more recognized as possible participants in the molecular processes underlying AD. Citrate synthase (CS), a key enzyme in the tricarboxylic acid (TCA) cycle, supports mitochondrial function and neurotransmitter synthesis, particularly acetylcholine (ACh), essential for cognition. Changes in CS activity affect citrate availability, influencing energy metabolism and neurotransmitter production. Choline, a precursor for ACh, is crucial for neuronal function. Lipid metabolism, oxidative stress reactions, and mitochondrial function can all be affected by aberrant citrate transport, and these changes are linked to dementia. Furthermore, the two main pathogenic characteristics of AD, tau hyperphosphorylation and amyloid-beta (Aβ) aggregation, may be impacted by disturbances in citrate homeostasis. The goal of this review is to clarify the complex function of citrate transporters in AD and provide insight into how they contribute to the development and course of the illness. We aim to provide an in-depth idea of which particular transporters are dysregulated in AD and clarify the functional implications of these dysregulated transporters in brain cells. To reduce neurodegenerative processes and restore metabolic equilibrium, we have also discussed the therapeutic potential of regulating citrate transport. Gaining insight into the relationship between citrate transporters and the pathogenesis of AD may help identify new indicators for early detection and creative targets for treatment. This study offers hope for more potent ways to fight this debilitating illness and is a crucial step in understanding the metabolic foundations of AD.

Advancing Alzheimer's disease pharmacotherapy: efficacy of glucocorticoid modulation with dazucorilant (CORT113176) in preclinical mouse models

BACKGROUND AND PURPOSE

Exposure to chronic stress and high levels of glucocorticoid hormones in adulthood has been associated with cognitive deficits and increased risk of Alzheimer's disease (AD). Dazucorilant has recently emerged as a selective glucocorticoid receptor (NR3C1) modulator, exhibiting efficacy in counteracting amyloid-β toxicity in an acute model of AD. We aim to assess the therapeutic potential of dazucorilant in reversing amyloid and tau pathologies through the inhibition of glucocorticoid receptor pathological activity, and providing additional evidence for its consideration in AD treatment.

EXPERIMENTAL APPROACH

The efficacy of dazucorilant was evaluated in two transgenic mouse models of amyloid pathology. The slowly progressing J20 and the aggressively pathological 5xFAD mice. Behavioural analysis was conducted to evaluate welfare, cognitive performances and anxiety levels. The activity of the glucocorticoid receptor system, neuroinflammation, amyloid burden and tau phosphorylation were examined in hippocampi.

KEY RESULTS

In both AD models, chronic treatment with dazucorilant improved working and long-term spatial memories along with the inhibition of glucocorticoid receptor-dependent pathogenic processes and the normalization of plasma glucocorticoid levels. Dazucorilant treatment also resulted in a reduction in tau hyperphosphorylation and amyloid production and aggregation. Additionally, dazucorilant seemed to mediate a specific re-localization of activated glial cells onto amyloid plaques in J20 mice, suggesting a restoration of physiological neuroinflammatory processes.

CONCLUSION AND IMPLICATIONS

Dazucorilant exhibited sustained disease-modifying effects in two AD models. Given that this compound has demonstrated safety and tolerability in human subjects, our results provide pre-clinical support for conducting clinical trials to evaluate its potential in AD.

Alzheimer disease seen through the lens of sex and gender

Alzheimer disease (AD) is a life-limiting neurodegenerative disorder that disproportionately affects women. Indeed, sex and gender are emerging as crucial modifiers of diagnostic and therapeutic pathways in AD. This Review provides an overview of the interactions of sex and gender with important developments in AD and offers insights into priorities for future research to facilitate the development and implementation of personalized approaches in the shifting paradigm of AD care. In particular, this Review focuses on the influence of sex and gender on important advances in the treatment and diagnosis of AD, including disease-modifying therapies, fluid-based biomarkers, cognitive assessment tools and multidomain lifestyle interventional studies.

Aβ impairs the LTP-related movement of endogenous CaMKII but not of exogenous GFP-CaMKII

Amyloid β (Aβ) inhibits hippocampal long-term potentiation (LTP; a form of synaptic plasticity thought to underly learning and memory) by inhibiting the stimulation-induced synaptic accumulation of the Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII). Notably, CaMKII inhibition rescues both CaMKII movement and LTP, indicating that CaMKII mediates both LTP and the Aβ-induced LTP impairment. Somewhat counterintuitively, we found here that overexpression of GFP-CaMKII also rescued the Aβ-induced impairment of CaMKII movement. For endogenous CaMKII, we confirmed that Aβ indeed induced impairment of movement, and that previous results with live-imaging approaches were not due to Aβ-induced dissociation of the CaMKII intrabody. For exogenous GFP-CaMKII, the effect did not depend on the expression level and was thus likely caused by the N-terminal GFP label. Surprisingly, placing the GFP label instead at the C-terminus (near the association domain) still allowed CaMKII holoenzyme formation and still protected from the Aβ-induced impairment of CaMKII movement. Thus, while our method allows replacing endogenous CaMKII with similar amounts of GFP-CaMKII, our results provide a rare example for GFP-CaMKII not recapitulating the function of endogenous CaMKII.

Synthesis of 18F-Labeled FC-119S and Its Tosyl Precursor

Animal models of Alzheimer's disease (AD) are essential for developing therapeutics and evaluating the efficacy of new drug candidates. Positron emission tomography (PET) is a useful method to monitor a major hallmark of the onset of AD, namely, the deposition of amyloid β peptide (Aβ) in the brain. [18F]FC-119S (1), a 2-pyridylbenzothiazole analog, has been applied as a radiotracer for PET visualization of Aβ plaques in an AD model, the 5xFAD mouse. Here, we present an alternative method for the automated synthesis of 18F-labeled 1 as a radiotracer for our animal PET studies. The first attempt at synthesizing 18F-labeled 1 using a mesyl precursor afforded desired product 1, although a nonfluorinated mesyl byproduct was eluted prior to 1 during purification by semipreparative high-performance liquid chromatography. An alternative synthesis using a tosyl precursor was applied to delay the elution of a nonfluorinated byproduct during chromatographic purification. As a result, 18F-labeled 1 was eluted without proximate byproducts during chromatographic purification, and routine production of 18F-labeled 1 was achieved for our AD studies using animal models.

Aquaporin 4 modulation drives amyloid burden and cognitive abilities in an APPPS1 mouse model of Alzheimer's disease

INTRODUCTION

Deficiency in the aquaporin-4 (AQP4) water channel has been linked to impaired amyloid beta (Aβ) clearance. However, a detailed morphopathological analysis of amyloid deposition following AQP4 therapeutic modulation remains unexplored.

METHODS

Two-month-old amyloid precursor protein presenilin 1 (APPPS1) mice were treated daily for 28 days with either the AQP4 facilitator N-(3-(Benzyloxy)pyridin-2-yl) benzene-sulfonamide (TGN-073) or the AQP4 inhibitor N-(1,3,4-thiadiazol-2-yl)pyridine-3-carboxamide dihydrochloride (TGN-020) (both at 200 mg/kg). Controls included vehicle-treated APPPS1 and WT C57BL/6J mice. Comprehensive histopathological, biochemical, and behavioral analyses were conducted.

RESULTS

Mice treated with AQP4 facilitator showed a significant reduction in total Aβ, fibrillar deposits, and soluble Aβ, while the AQP4 inhibitor caused a substantial increase in brain Aβ. AQP4-facilitator treatment also reduced Aβ40 levels and Aβ40/Aβ42 ratio, whereas the inhibitor treatment increased both Aβ40 and Aβ42. Additionally, facilitator-treated mice demonstrated reduced anxiety and improved memory performance.

DISCUSSION

These findings suggest that AQP4 modulation is a promising strategy to enhance Aβ clearance and a potential therapeutic target in Alzheimer's disease.

HIGHLIGHTS

Intramural periarterial drainage of the interstitial fluid mediated by aquaporin-4 (AQP4) is a key element that ensures clearance of catabolites/Aβ peptide from within the brain parenchyma. Inhibition of AQP4 in an APPPS1 mouse model of AD leads to increased amyloid deposition and deficient behavior compared to untreated transgenic animals. Pharmaceutical facilitation of AQP4 in the same APPPS1 mouse model leads to a massive decrease in amyloid burden and improves the behavioral performance of the animals compared to untreated control APPPS1 mice.

Functionalized carbon dots with guanidine salt ionic liquid regulate oxidative damage and amyloid aggregation

An imbalance in the brain microenvironment, involving oxidative stress and β-amyloid (Aβ) accumulation, is thought to be one of the primary characteristics of early Alzheimer's disease (AD). To address the intricate pathophysiology of AD, therapeutic approaches that can concurrently control several diseases in the AD microenvironment are desperately needed. This study created a guanidine salt ionic liquid functionalized carbon dots (CDs@TGM-IL) to mitigate Aβ aggregation-induced cytotoxicity and scavenge reactive oxygen species (ROS) simultaneously. In vitro studies have shown that CDs@TGM-IL can effectively inhibit Aβ42 protein aggregation, disaggregate mature Aβ42 fibrils, and effectively remove ROS. In vivo studies have found that CDs@TGM-IL can cross the blood-brain barrier (BBB) and improve cognitive performance in AD mice. Just as importantly, CDs@TGM-IL has been shown to have unparalleled biocompatibility. This means that CDs@TGM-IL is expected to be a possible treatment for AD.

The neuroinflammatory role of microRNAs in Alzheimer's disease: pathological insights to therapeutic potential

Alzheimer's disease (AD) is a neurodegenerative disease and the most common cause of dementia, contributing to around 60-80% of cases. The main pathophysiology of AD is characterized by an abnormal accumulation of protein aggregates extracellularly (beta-amyloid plaques) and intracellularly (neurofibrillary tangles of hyperphosphorylated tau). However, an increasing number of studies have also suggested neuroinflammation may have a crucial role in precipitating the cascade reactions that result in the development of AD neuropathology. In particular, several studies indicate microRNAs (miRNAs) can act as regulatory factors for neuroinflammation in AD, with potential to affect the occurrence and/or progression of AD inflammation by targeting the expression of multiple genes. Therefore, miRNAs may have potential as therapeutic targets for AD, which requires more research. This article will review the existing studies on miRNAs that have been identified to regulate neuroinflammation, aiming to gain further insights into the specific regulatory processes of miRNAs, highlight the diagnostic and therapeutic potential of miRNAs as biomarkers in AD, as well as current challenges, and suggest the further work to bridge the gap in knowledge to utilize miRNAs as therapeutic targets for AD.

Alzheimer's disease and age-related macular degeneration: Shared and distinct immune mechanisms

Alzheimer's disease (AD) and age-related macular degeneration (AMD) represent the leading causes of dementia and vision impairment in the elderly, respectively. The retina is an extension of the brain, yet these two central nervous system (CNS) compartments are often studied separately. Despite affecting cognition vs. vision, AD and AMD share neuroinflammatory pathways. By comparing these diseases, we can identify converging immune mechanisms and potential cross-applicable therapies. Here, we review immune mechanisms highlighting the shared and distinct aspects of these two age-related neurodegenerative conditions, focusing on responses to hallmark disease manifestations, the opposite role of overlapping immune risk loci, and potential unified therapeutic approaches. We also discuss unique tissue requirements that may dictate different outcomes of conserved immune mechanisms and how we can reciprocally utilize lessons from AD therapeutics to AMD. Looking forward, we suggest promising directions for research, including the exploration of regenerative medicine, gene therapies, and innovative diagnostics.

Subtle Alterations in Hippocampal Neuronal Activity Coincide With Early Sex-Specific Differences in Amyloidosis and Microglia in a Pre-Symptomatic Mouse Model of Alzheimer-Like Pathology

Growing evidence highlights sex-related differences in the pathogenesis of Alzheimer's disease (AD). Yet, early impact of sex on neuronal activity and microglia in the hippocampus, a main site of memory formation and one of the most vulnerable brain areas in AD, remains poorly understood. We thus assessed these issues by using APPPS1 mouse model of AD-like amyloid pathology at a pre-symptomatic stage (5-6 months). Our electrophysiological data point to opposite alterations in hippocampal CA1 neurons' basal glutamatergic neurotransmission and response to excitatory inputs between male and female APPPS1 mice. These complex changes in neuronal activity are likely to precede plasticity impairments, which do not yet translate into sexual dimorphism of Long-Term Potentiation (LTP) at the studied age. Alteration in synaptic transmission in males coincides with an increased number and coverage of microglia, together with increased plaque coverage, as compared to the female hippocampus. Such increased microgliosis in males is accompanied by complex sex-related differences in the expression of specific transcriptomic markers Disease-Associated Microglia (DAM)/Microglial neurodegenerative phenotype (MGnD), whereas homeostatic (M0) markers were unaffected. Our data show for the first time that subtle alterations in hippocampal neuronal activity coincide with early sex-related differences in amyloidosis and microglia already at the pre-symptomatic stage of AD-like pathology.

Alzheimer's disease knowledge graph enhances knowledge discovery and disease prediction

OBJECTIVE

To construct an Alzheimer's Disease Knowledge Graph (ADKG) by extracting and integrating relationships among Alzheimer's disease (AD), genes, variants, chemicals, drugs, and other diseases from biomedical literature, aiming to identify existing treatments, potential targets, and diagnostic methods for AD.

METHODS

We annotated 800 PubMed abstracts (ADERC corpus) with 20,886 entities and 4935 relationships, augmented via GPT-4. A SpERT model (SciBERT-based) trained on this data extracted relations from PubMed abstracts, supported by biomedical databases and entity linking refined via abbreviation resolution/string matching. The resulting knowledge graph trained embedding models to predict novel relationships. ADKG's utility was validated by integrating it with UK Biobank data for predictive modeling.

RESULTS

The ADKG contained 3,199,276 entity mentions and 633,733 triplets, linking >5K unique entities and capturing complex AD-related interactions. Its graph embedding models produced evidence-supported predictions, enabling testable hypotheses. In UK Biobank predictive modeling, ADKG-enhanced models achieved higher AUROC of 0.928 comparing to 0.903 without ADKG enhancement.

CONCLUSION

By synthesizing literature-derived insights into a computable framework, ADKG bridges molecular mechanisms to clinical phenotypes, advancing precision medicine in Alzheimer's research. Its structured data and predictive utility underscore its potential to accelerate therapeutic discovery and risk stratification.

Early involvement of D-serine in β-amyloid-dependent pathophysiology

The N-methyl-D-aspartate subtype of glutamate receptors (NMDAR) is a key regulator of brain plasticity encoding learning and memory. In addition to glutamate, NMDAR activation requires the binding of the co-agonist D-serine. The beta-amyloid (Aß) peptide which accumulates in Alzheimer's disease (AD), affects the D-serine-dependent NMDAR activation in vitro, but whether this alteration would significantly contribute to AD-related pathophysiology and memory deficits remains unclear. Herein, we report a decrease in the maximal pool of recruitable NMDAR and in the expression of NMDAR-dependent long-term potentiation together with impaired basal neurotransmission at CA3/CA1 synapses from hippocampal slices of 5xFAD mouse, an AD-related model with elevated Aß levels. The NMDAR synaptic impairments develop from 1.5 to 2 months of age with the initial rise of Aß and is correlated to a transient increase in D-serine levels. Deficits in working and spatial memories as well as cognitive flexibility then occurred in 10-12 months-old animals. Importantly, the NMDA-related synaptic deregulations (but not the altered basal neurotransmission) and behavioral impairments (working and cognitive flexibility) are prevented or reduced (spatial memory) in 5xFAD mice devoid of D-serine after genetic deletion of its synthesis enzyme serine racemase. Altogether, these results therefore provide in vivo evidence for the implication of D-serine at least in the early pathogenic signatures of AD driven by the increase in amyloid load suggesting that the recent proposal of preventive therapy of AD by administration of the precursor L-serine remains questionable.

Advancing Nanomaterial-Based Strategies for Alzheimer's Disease: A Perspective

Alzheimer's disease (AD) is a complex neurodegenerative disorder and the most common cause of dementia. By 2050, the number of AD cases is projected to exceed 131 million, placing significant strain on healthcare systems and economies worldwide. The pathogenesis of AD is multifactorial, involving hypotheses/mechanisms, such as amyloid-β (Aβ) plaques, tau protein hyperphosphorylation, cholinergic neuron damage, oxidative stress, and inflammation. Despite extensive research, the complexity of these potentially entangled mechanisms has hindered the development of treatments that can reverse disease progression. Nanotechnology, leveraging the unique physical, electrical, magnetic, and optical properties of nanomaterials, has emerged as a promising approach for AD treatment. In this Perspective, we first outlined the major current pathogenic hypotheses of AD and then reviewed recent advances in nanomaterials in addressing these hypotheses. We have also discussed the challenges in translating nanomaterials into clinical applications and proposed future directions, particularly the development of multifunctional and multitarget nanomaterials, to enhance their therapeutic efficacy and clinical applicability in AD treatment.

Discovery of an ApoE4-targeted small-molecule SirT1 enhancer for the treatment of Alzheimer's disease

Decreased expression of sirtuin 1 (SirT1) has been implicated in Alzheimer's disease (AD), and as we previously reported, is related to transcriptional repression by the major risk factor for sporadic AD, apolipoprotein E4 (ApoE4). Herein we describe the discovery of an orally brain-permeable small-molecule, DDL-218, that enhanced SirT1 in ApoE4-expressing neuronal cells and a murine AD model. DDL-218 increased the transcription factor NFYb resulting in upregulation of PRMT5. Mechanistic and modeling studies show that binding of ApoE4 to the SirT1 gene promoter can be displaced by PRMT5 leading to increased SirT1 transcription. DDL-218 treatment elicited improvement in memory in the AD model, suggesting that DDL-218 enhancement of neurotrophic SirT1 in the brain has potential to modulate neuronal activity that may clinically provide an improvement in cognitive function and complement the current anti-Aβ antibody monotherapy. Our findings support further development of DDL-218 as a novel ApoE4-targeted therapeutic candidate for AD.

Emerging nano-derived therapy for the treatment of dementia: a comprehensive review

Dementia includes a variety of neurodegenerative diseases that affect and target the brain's fundamental cognitive functions. It is undoubtedly one of the diseases that affects people globally. The ameliorating the disease is still not known; the symptoms, however, can be prevented to an extent. Dementia encompasses Alzheimer's disease, Parkinson's disease, Huntington's disease, Lewy body dementia, mixed dementia, and various other diseases. The aggregation of β-amyloid protein plaques and the formation of neurofibrillary tangles have been concluded as the foremost cause for the onset of the disease. As the cases climb, new neuroprotective methods are being developed in the form of new drug delivery systems that provide targeted delivery. Herbal drugs like Ashwagandha, Brahmi, and Cannabis have shown satisfactory results by not only treating the symptoms but have also been shown to reduce and ameliorate the formation of amyloid plaque formation. This article explores the intricate possibilities of drug delivery and the absolute use of herbal drugs to target neurodegenerative diseases. The various possibilities of nanotechnology currently available with new emerging techniques are also discussed.

P-glycoprotein and Alzheimer's Disease: Threats and Opportunities

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects more than 50 million people worldwide. One of the hallmark features of AD is the accumulation of amyloid β-peptide (Aβ) protein in the brain. P-glycoprotein (P-gp) is a membrane-bound protein expressed in various tissues, including the cerebrovascular endothelium. It plays a crucial role in the efflux of toxic substances, including Aβ, from the brain. Aberrations in P-gp levels or activity have been implicated in the pathogenesis of AD by promoting the accumulation of Aβ in the brain. Therefore, modulating the P-gp function represents a promising therapeutic strategy for treating AD. P-gp has multiple substrate binding sites, creating the potential for substrates to fall into complementation groups based on these sites; two substrates in the same complementation group may compete with one other, but two substrates in different groups may exhibit cooperativity. Thus, a given P-gp substrate may interfere with Aβ efflux whereas another may promote clearance. These threats and opportunities, as well as other aspects of P-gp relevance to AD, are discussed here.

Identification and validation of biomarkers in Alzheimer's disease based on machine learning algorithms and single-cell sequencing analysis

OBJECTIVE

Alzheimer's disease (AD) is a complicated neurodegenerative disease with unknown pathogenesis. Identifying possible diagnostic markers of AD is essential to elucidate its mechanisms and facilitate diagnosis.

METHODS

A total of 295 samples (153 AD and 142 normal) were analyzed from two datasets (GSE122063 and GSE132903) in the Gene Express Omnibus (GEO) database. Differentially expressed genes (DEGs) between groups were identified and dimensionality reduction was applied to identify feature genes (key genes) using three algorithms of machine learning including least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), and Random forest (RF). In addition, we obtained sample data from single-cell RNA datasets GSE157827, GSE167490, and GSE174367 to classify cells into different types and examined changes in gene expression and their correlation with AD progression. Immunofluorescence assay was used to verify the expression of key genes in animal experiments.

RESULTS

To identify diagnostic genes associated with AD, we analyzed two datasets and identified 379 DEGs which might be related to the onset of AD, and 115 of them were up-regulated and 264 down-regulated. Three algorithms of machine learning were adopted to reduce the dimensions of these DEGs and finally six core DEGs CD86, SCG3, VGF, PRKCG, SPP1, and TPI1 of AD were identified. Diagnostic analyses showed that SCG3 was substantially down-regulated in the AD group, and its AUC was higher in both the training and validation sets (0.845, 0.927, and 0.917, respectively). Transcriptome sequencing results further revealed that SCG3 expression was down-regulated in multiple cell types in the AD group and SCG3 expression in the hippocampus was found significantly reduced in the AD group.

CONCLUSIONS

This study systematically identified and validated the potential of SCG3 as an early diagnostic biomarker for AD through several technical strategies. The findings provided new biomarkers for early detection of AD and laid a foundation for future clinical applications.

Differential neuronal vulnerability to C9orf72 repeat expansion driven by Xbp1-induced endoplasmic reticulum-associated degradation

Neurodegenerative diseases are characterized by the localized loss of neurons. Why cell death is triggered only in specific neuronal populations and whether it is the response to toxic insults or the initial cellular state that determines their vulnerability is unknown. To understand individual cell responses to disease, we profiled their transcriptional signatures throughout disease development in a Drosophila model of C9orf72 (G4C2) repeat expansion (C9), the most common genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis. We identified neuronal populations specifically vulnerable or resistant to C9 expression and found an upregulation of protein homeostasis pathways in resistant neurons at baseline. Overexpression of Xbp1s, a key regulator of the unfolded protein response and a central node in the resistance network, rescues C9 toxicity. This study shows that neuronal vulnerability depends on the intrinsic transcriptional state of neurons and that leveraging resistant neurons' properties can boost resistance in vulnerable neurons.

Key biomarkers in Alzheimer's disease: Insights for diagnosis and treatment strategies

Alzheimer's disease (AD) remains a significant global health challenge, characterized by its progressive neurodegeneration and cognitive decline. The urgent need for early diagnosis and effective treatment necessitates the identification of reliable biomarkers that can illuminate the underlying pathophysiology of AD. This review provides a comprehensive overview of the latest advancements in biomarker research, focusing on their applications in diagnosis, prognosis, and therapeutic development. We delve into the multifaceted landscape of AD biomarkers, encompassing molecular, imaging, and fluid-based markers. The integration of these biomarkers, including amyloid-β and tau proteins, neuroimaging modalities, cerebrospinal fluid analysis, and genetic risk factors, offers a more nuanced understanding of AD's complex etiology. By leveraging the power of precision medicine, biomarker-driven approaches can enable personalized treatment strategies and enhance diagnostic accuracy. Moreover, this review highlights the potential of biomarker research to accelerate drug discovery and development. By identifying novel therapeutic targets and monitoring disease progression, biomarkers can facilitate the evaluation of experimental treatments and ultimately improve patient outcomes. In conclusion, this review underscores the critical role of biomarkers in advancing our comprehension of AD and driving the development of effective interventions. By providing a comprehensive overview of the current state-of-the-art, this work aims to inspire future research and contribute to the goal of conquering AD.

Deep Visual Proteomics maps proteotoxicity in a genetic liver disease

Protein misfolding diseases, including α1-antitrypsin deficiency (AATD), pose substantial health challenges, with their cellular progression still poorly understood1-3. We use spatial proteomics by mass spectrometry and machine learning to map AATD in human liver tissue. Combining Deep Visual Proteomics (DVP) with single-cell analysis4,5, we probe intact patient biopsies to resolve molecular events during hepatocyte stress in pseudotime across fibrosis stages. We achieve proteome depth of up to 4,300 proteins from one-third of a single cell in formalin-fixed, paraffin-embedded tissue. This dataset reveals a potentially clinically actionable peroxisomal upregulation that precedes the canonical unfolded protein response. Our single-cell proteomics data show α1-antitrypsin accumulation is largely cell-intrinsic, with minimal stress propagation between hepatocytes. We integrated proteomic data with artificial intelligence-guided image-based phenotyping across several disease stages, revealing a late-stage hepatocyte phenotype characterized by globular protein aggregates and distinct proteomic signatures, notably including elevated TNFSF10 (also known as TRAIL) amounts. This phenotype may represent a critical disease progression stage. Our study offers new insights into AATD pathogenesis and introduces a powerful methodology for high-resolution, in situ proteomic analysis of complex tissues. This approach holds potential to unravel molecular mechanisms in various protein misfolding disorders, setting a new standard for understanding disease progression at the single-cell level in human tissue.

The relationship between postoperative delirium and plasma amyloid beta oligomer

Postoperative delirium (POD) is a frequent complication in older people undergoing general anesthesia surgery. We investigated the potential link between Alzheimer's disease and POD by comparing plasma amyloid-beta oligomer levels (measured using the multimer detection system, MDS-OAβ) in patients who developed POD after general anesthesia surgery with those who did not. A total of 104 eligible participants were screened daily for delirium for three days postoperatively. After propensity score matching based on the ApoE4 allele, the final analysis included 31 patients with POD and 31 without POD. In the ICU, patients with delirium underwent immediate assessment with the Korean version of the Delirium Rating Scale-98 (K-DRS-98) and plasma MDS-OAβ levels. The control group (those without POD) received the same tests on the third postoperative day. Patients with POD had significantly higher MDS-OAβ values compared to those without POD. Within the POD group, MDS-OAβ values positively correlated with K-DRS-98 scores (both severity and total scores). These findings suggest an association between POD in older people undergoing general anesthesia surgery and elevated plasma amyloid oligomer levels. To definitively establish causality, further prospective studies are necessary.

Hippocampal Neural Stem Cell Exosomes Promote Brain Resilience against the Impact of Tau Oligomers

A promising therapeutic intervention for preventing the onset and progression of Alzheimer's disease is to protect and improve synaptic resilience, a well-established early vulnerability associated with the toxic effects of oligomers of amyloid β (AβO) and Tau (TauO). We have previously reported that exosomes from hippocampal neural stem cells (NSCs) protect synapses against AβO. Here, we demonstrate how exosomes can also shield against TauO toxicity in adult mice synapses, potentially benefiting primary and secondary tauopathies. Exosomes from hippocampal NSCs (NSCexo) or mature neurons (MNexo) were delivered intracerebroventricularly to adult wild-type male mice (C57Bl6/J). After 24 h, TauO were administered to suppress long-term potentiation (LTP) and memory, measured by electrophysiology and contextual memory deficits measured using novel object recognition test. We also assessed TauO binding to synapses using isolated synaptosomes and cultured hippocampal neurons. Furthermore, mimics of select miRNAs present in NSCexo were delivered intracerebroventricularly to mice prior to assessment of TauO-induced suppression of hippocampal LTP. Our results showed that NSC-, not MN-, derived exosomes, prevented TauO-induced memory impairment, LTP suppression, and reduced Tau accumulation and TauO internalization in synaptosomes. These findings suggest that NSC-derived exosomes can protect against synaptic dysfunction and memory deficits induced by both AβO and TauO, offering a novel therapeutic strategy for multiple neurodegenerative states.

Dynamic changes of hippocampal dendritic spines in Alzheimer's disease mice among the different stages

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β (Aβ) peptides and a progressive decline in cognitive function. Hippocampus as a crucial brain area for learning and memory, is also adversely affected by AD's pathology. The accumulation of Aβ is often associated with the loss of dendritic spines of the hippocampus. However, the dynamic alterations in dendritic spines throughout AD progression are not fully understood. To investigate it, we conducted in-vivo imaging in two mouse models representing the early and late stages of AD pathology: young mice injected with Aβ1-42 oligomers and APP/PS1 transgenic mice. In the early-stage AD model, imaging was conducted at third- and fifth- weeks post-injection. In the late-stage AD model, a four-month imaging began at 14 months old. The imaging results showed spine elimination in both models. Notably, acute Aβ exposure was linked to heightened spine loss on secondary dendrites, while in the late stage the primary effect was on tertiary dendrites. Concurrently, with the metabolism of Aβ, cognition recovered to some extent by five weeks post Aβ1-42 exposure. These findings suggested that dendritic spine plasticity was impaired during the development of AD, as evidenced by increasing spine loss at different levels. However, the cognitive recovery observed in early-stage AD model mice may indicate a compensatory structural reorganization, highlighting the potential of early intervention to mitigate disease progression. Our results provide novel insights into the neurotoxic effects of Aβ1-42 and may contribute to the development of therapeutic strategies for AD.

Presenilin, γ-Secretase, and the Search for Pathogenic Triggers of Alzheimer's Disease

Cerebral plaques of the amyloid β-peptide (Aβ) are a defining pathology in Alzheimer's disease (AD). The amyloid hypothesis of AD pathogenesis has dominated the field for over 30 years, ostensibly validated by rare AD-causing mutations in the substrate and enzyme that produce Aβ. The γ-secretase complex carries out intramembrane proteolysis of the substrate derived from the amyloid precursor protein (APP). Mutations in APP and presenilin, the catalytic component of γ-secretase, typically increase the ratio of aggregation-prone 42-residue Aβ (Aβ42) over the more soluble 40-residue form (Aβ40). Nevertheless, the inability to clarify how Aβ aggregation leads to neurodegeneration, along with poor progress in developing effective AD therapeutics that target Aβ, raises concern about whether Aβ is the primary disease driver. γ-Secretase carries out processive proteolysis on the APP substrate, producing long Aβ peptides that are generally trimmed in tripeptide intervals to shorter secreted peptides. Recent studies on effects of AD-causing mutations on the complicated proteolytic processing of the APP substrate by γ-secretase has led to the discovery that these mutations reduce─but do not abolish─processive proteolysis. Reduced proteolysis is apparently due to stabilization of enzyme-substrate complexes, and these stalled substrate-bound γ-secretase complexes can trigger synaptic degeneration even in the absence of Aβ production. Thus, the stalled process rather than the proteolytic products may be a principal initiator of AD pathogenesis. This new amyloid-independent hypothesis suggests that pharmacological agents that rescue stalled γ-secretase enzyme-substrate complexes might be effective therapeutics for AD prevention and/or treatment.

Bibliometric and Visual Analysis of Alzheimer's Disease and Herpes Simplex Virus Type 1 Infection Between 1990 and 2024

Background

Recently, some studies suggested that Herpes simplex virus type 1 (HSV-1) infection is an important environmental factor for Alzheimer's disease(AD). The literature on research about HSV-1 infection and AD is emerging. This study used the bibliometric method to investigate the relationship between HSV-1 infection and AD.

Methods

We searched the Web of Science Core Collection for relevant literature on AD and HSV-1 from 1990 to 2024. Bibliometric and visualization analyses were performed using VOSviewer and CiteSpace.

Results

From 1990 to 2024, the number of publications showed an increasing trend. The United States made the largest contributions in productivity. The University of Manchester was the most productive organization. Professor Ruth F. Itzhaki was the most influential researcher. The Journal of Alzheimer's Disease had published the most articles. Research on the mechanisms by which HSV infection contributes to AD remains a hotspot in the field, and future studies may further focus on antiviral therapeutic strategies targeting HSV-1 infection.

Conclusion

Our analysis provides basic information about research in AD and HSV-1. The current research hotspots in this field mainly include the mechanism of AD caused by HSV-1, and antiviral drugs to treat or prevent AD.

Organelle perturbation in Alzheimer's disease: do intracellular amyloid-ß and the fragmented Golgi mediate early intracellular neurotoxicity?

Alzheimer's disease is a devastating and incurable neurological disease. Most of the current research has focused on developing drugs to clear the extracellular amyloid plaques in the brain of Alzheimer's disease patients. However, this approach is limited as it does not treat the underlying cause of the disease. In this review, we highlight the evidence in the field showing that the accumulation of intracellular toxic amyloid-ß could underpin very early events in neuronal death in both familial early-onset and sporadic late-onset alzheimer's disease. Indeed, intracellular amyloid-ß, which is produced within intracellular compartments, has been shown to perturb endosomal and secretory organelles, in different neuronal models, and the brain of Alzheimer's patients, leading to membrane trafficking defects and perturbation of neuronal function associated with cognition defects. The Golgi apparatus is a central transport and signaling hub at the crossroads of the secretory and endocytic pathways and perturbation of the Golgi ribbon structure is a hallmark of Alzheimer's disease. Here, we discuss the role of the Golgi as a major player in the regulation of amyloid-β production and propose that the Golgi apparatus plays a key role in a cellular network which can seed the onset of Alzheimer's disease. Moreover, we propose that the Golgi is central in an intracellular feedback loop leading to an enhanced level of amyloid-β production resulting in early neuronal defects before the appearance of clinical symptoms. Further advances in defining the molecular pathways of this intracellular feedback loop could support the design of new therapeutic strategies to target a primary source of neuronal toxicity in this disease.

Identification of the binding site and immunoreactivity of anti-Aβ antibody 11A1: Comparison with the toxic conformation-specific TxCo-1 antibody

Since the advent of anti-amyloid β (Aβ) immunotherapy, exemplified by lecanemab, the development of effective therapeutic agents with minimal side effects has become an urgent priority. Over the past two decades, a number of antibodies have been developed that target toxic Aβ species. The 11A1 antibody is one such example, and is made from E22P-Aβ9-35, which is prone to adopt a toxic conformation with a turn at positions 22/23, as an antigen. This antibody is unique in that it stains not only extracellular but also intracellular Aβ in human AD brains. To identify its recognition domain, we performed X-ray crystallography of 11A1 in complex with E22P-Aβ10-34. We found that 11A1 is a novel N-terminal antibody that recognizes Tyr10-His14 of Aβ. Immunohistochemical studies showed that 11A1 stains senile plaques and vascular Aβ aggregates in brain samples of AD patients. On the other hand, 11A1 recognized Aβ aggregates in neurons, astrocytes, perivascular tissue, and microvesicles of non-AD patients, suggesting that 11A1 can detect a wide range of Aβ types regardless of AD pathology. In contrast, the recently developed TxCo-1 antibody, which specifically recognizes the toxic turn at positions 22/23 of Aβ42, stained only senile plaques and vascular Aβ aggregates from AD patients, but not Aβ species from non-AD patients. These results suggest that the toxic turn structure may be one of the key epitopes for achieving high affinity for pathological Aβ aggregates while minimizing nonspecific binding to aggregates unrelated to pathology.

Interactions between daily sleep-wake rhythms, γ-secretase, and amyloid-β peptide pathology point to complex underlying relationships

Disrupted or insufficient sleep is a well-documented risk factor for Alzheimer's disease (AD) and related dementias. Previous studies in our lab and others have shown that chronic fragmentation of the daily sleep-wake rhythm in mice can accelerate the development of AD-related neuropathology in the brain, including increases in the levels of amyloid-β (Aβ). Although sleep is known to increase clearance of Aβ via the glymphatic system, little is known about the effect of sleep on Aβ production and the role this might play in amyloid deposition. To examine the relationship of Aβ production and its interaction with sleep and sleep dysfunction, we treated mice from an APP × PS1 mutant knock-in line (APPΔNLh/ΔNLh × PS1P264L/P264L) with an inhibitor of γ-secretase (LY-450,139; Semagacestat®) during a protocol of mild sleep fragmentation (SF). Compared to the male mice, the female mice slept less, and had more Aβ pathology. Semagacestat treatment reduced Aβ, but only in the most soluble extractable fraction. Although the female mice showed an increase in the amount of Aβ following SF, this effect was blocked by Semagacestat, an effect that was not seen in the male mice. SF also led to a significant, sex-dependent changes in the relative amounts of C-terminal fragments of the amyloid precursor protein, the immediate substrate of the γ-secretase enzyme. These findings indicate that the relationship between disruption of the daily sleep-wake rhythm and the development of AD-related pathology is complex, and may involve unappreciated interactions with biological sex. Consideration of these factors is necessary for a better understanding of AD risk, especially the elevated risk in women.

In Vivo Seeding of Amyloid-β Protein and Implications in Modeling Alzheimer's Disease Pathology

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by extracellular plaques containing amyloid β-protein (Aβ) and intracellular neurofibrillary tangles formed by tau. Cerebral Aβ accumulation initiates a noxious cascade that leads to irreversible neuronal degeneration and memory impairment in older adults. Recent advances in Aβ seeding studies offer a promising avenue for exploring the mechanisms underlying amyloid deposition and the complex pathological features of AD. However, the extent to which inoculated Aβ seeds can induce reproducible and reliable pathological manifestations remains unclear due to significant variability across studies. In this review, we will discuss several factors that contribute to the induction or acceleration of amyloid deposition and consequent pathologies. Specifically, we focus on the diversity of host animals, sources and recipe of Aβ seeds, and inoculating strategies. By integrating these key aspects, this review aims to offer a comprehensive perspective on Aβ seeding in AD and provide guidance for modeling AD pathogenesis through the exogenous introduction of Aβ seeds.

Selective imaging probes for differential detection of pathological tau polymorphs in tauopathies

Tauopathies, including Alzheimer's disease (AD), Pick's disease (PiD), progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), are characterized by the misfolding and pathological aggregation of the tau protein, leading to neurodegeneration. Although the pathogenesis of these diseases is still a matter for debate, the formation of amyloid inclusions still represents the only histopathological hallmark available. Tau inclusions are not the same in terms of structure and morphology, and different tauopathies are characterized by different polymorphs. Remarkably, the selective detection of these polymorphs is crucial for differential diagnosis, disease monitoring and evaluation of the potential harmfulness of polymorphs, with a significant impact on drug discovery. This review discusses recent advances in the development of imaging probes designed for the selective detection of pathological tau forms associated with specific tauopathies. We explore the application of compounds that can target tau polymorphs characteristic of AD, PiD, PSP and CBD. In particular, we focus on discussing the probes' selectivity and sensitivity in distinguishing between the different tauopathy-associated polymorphs in preclinical settings. The progress and the weaknesses in this field are discussed, to guide the researchers in identifying accurate and potent probes for the selective diagnosis of these different neurodegenerative diseases.

Polyoxometalates as effective inhibitors of insulin amyloid fibrils: a promising therapeutic avenue

Insulin is listed on the WHO model list of essential medicines for a basic healthcare system. Due to its usage at regular intervals on diabetic patients, a disease condition called injection amyloidosis exists due to the propensity of insulin to form fibrils. Hence, it is essential to understand the aggregation of the protein insulin and understand the role of fibrillation of the protein insulin and possible inhibition. In this particular investigation, insulin fibrils were produced in a controlled environment. The study focused on exploring the potential of a special class of inorganic nanomaterials known as polyoxometalates (POMs) to inhibit the formation of these insulin amyloid fibrils. Four specific POMs-phosphomolybdic acid (PMA), silicomolybdic acid (SMA), tungstosilicic acid (TSA), and phosphotungstic acid (PTA)-were selected for assessing the inhibition of fibril formation by POMs using the Thioflavin T (ThT) assay. The molecular docking study also shows the binding sites of POMs with insulin. The results provided promising insights into the inhibitory effects of POMs on insulin amyloid fibrils. This investigation opens up potential avenues for exploring the application of Keggin POMs in the context of neurodegeneration.

Unique N-glycosylation signatures in human iPSC derived microglia activated by Aβ oligomer and lipopolysaccharide

Microglia are the immune cells in the central nervous system (CNS) and become pro-inflammatory/activated in Alzheimer's disease (AD). Cell surface glycosylation plays an important role in immune cells; however, the N-glycosylation and glycosphingolipid (GSL) signatures of activated microglia are poorly understood. Here, we study comprehensively combined transcriptomic and glycomic profiles using human induced pluripotent stem cells-derived microglia (hiMG). Distinct changes in N-glycosylation patterns in amyloid-β oligomer (AβO) and LPS-treated hiMG were observed. In AβO-treated cells, the relative abundance of bisecting N-acetylglucosamine (GlcNAc) N-glycans decreased, corresponding with a downregulation of MGAT3. The sialylation of N-glycans increased in response to AβO, accompanied by an upregulation of genes involved in N-glycan sialylation (ST3GAL4 and 6). Unlike AβO-induced hiMG, LPS-induced hiMG exhibited a decreased abundance of complex-type N-glycans, aligned with downregulation of mannosidase genes (MAN1A1, MAN2A2, and MAN1C1) and upregulation of ER degradation related-mannosidases (EDEM1-3). Fucosylation increased in LPS-induced hiMG, aligned with upregulated fucosyltransferase 4 (FUT4) and downregulated alpha-L-fucosidase 1 (FUCA1) gene expression, while sialofucosylation decreased, aligned with upregulated neuraminidase 4 (NEU4). Inhibition of sialylation and fucosylation in AβO- and LPS-induced hiMG alleviated pro-inflammatory responses. However, the GSL profile did not exhibit significant changes in response to AβO or LPS activation, at least in the 24-hour stimulation timeframe. AβO- and LPS- specific glycosylation changes could contribute to impaired microglia function, highlighting glycosylation pathways as potential therapeutic targets for AD.

Danggui Shaoyao San ameliorates Alzheimer's disease by regulating lipid metabolism and inhibiting neuronal ferroptosis through the AMPK/Sp1/ACSL4 signaling pathway

Introduction

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive decline; recent studies suggest that neuronal ferroptosis plays a key role in its pathogenesis. Danggui Shaoyao San (DSS), a traditional Chinese medicine formula, has shown demonstrated neuroprotective effects, but its precise mechanisms in AD treatment remain unclear. This study aims to investigate the mechanism of DSS in treating AD by inhibiting neuronal ferroptosis, explore whether DSS alleviates AD by suppressing neuronal ferroptosis via the AMPK/Sp1/ACSL4 pathway.

Methods

Chemical composition of DSS was identified by LC-MS/MS, followed by network pharmacology to predict targets and pathways. Molecular docking assessed binding affinities between DSS compounds and key proteins (AMPK, Sp1, ACSL4). In vivo experiments on APP/PS1 mice evaluated DSS effects on cognitive function, oxidative stress markers, lipid peroxidation, and ferroptosis-related proteins.

Results

Network pharmacology analysis suggested that DSS regulates lipid metabolism and inhibits neuronal ferroptosis via the AMPK pathway. Molecular docking revealed strong binding affinities between DSS compounds and AMPK downstream proteins, Sp1 and ACSL4. In vivo experiments showed that DSS improved cognitive function, enhanced antioxidant capacity, reduced lipid peroxide accumulation, and decreased Fe2+ content in brain tissue. Furthermore, DSS increased the expression of FTH, p-AMPK, and GPX4 while decreasing Sp1 and ACSL4 levels, thereby inhibiting ferroptosis.

Conclusion

DSS alleviates AD symptoms by suppressing neuronal ferroptosis via the AMPK/Sp1/ACSL4 axis, representing a novel lipid metabolism-targeted therapeutic strategy.