Neuropathological alterations in Alzheimer disease

Modulation of the Nogo signaling pathway to overcome amyloid-β-mediated neurite inhibition in human pluripotent stem cell-derived neurites

JOURNAL/nrgr/04.03/01300535-202509000-00026/figure1/v/2024-11-05T132919Z/r/image-tiff Neuronal cell death and the loss of connectivity are two of the primary pathological mechanisms underlying Alzheimer's disease. The accumulation of amyloid-β peptides, a key hallmark of Alzheimer's disease, is believed to induce neuritic abnormalities, including reduced growth, extension, and abnormal growth cone morphology, all of which contribute to decreased connectivity. However, the precise cellular and molecular mechanisms governing this response remain unknown. In this study, we used an innovative approach to demonstrate the effect of amyloid-β on neurite dynamics in both two-dimensional and three-dimensional culture systems, in order to provide more physiologically relevant culture geometry. We utilized various methodologies, including the addition of exogenous amyloid-β peptides to the culture medium, growth substrate coating, and the utilization of human-induced pluripotent stem cell technology, to investigate the effect of endogenous amyloid-β secretion on neurite outgrowth, thus paving the way for potential future applications in personalized medicine. Additionally, we also explore the involvement of the Nogo signaling cascade in amyloid-β-induced neurite inhibition. We demonstrate that inhibition of downstream ROCK and RhoA components of the Nogo signaling pathway, achieved through modulation with Y-27632 (a ROCK inhibitor) and Ibuprofen (a Rho A inhibitor), respectively, can restore and even enhance neuronal connectivity in the presence of amyloid-β. In summary, this study not only presents a novel culture approach that offers insights into the biological process of neurite growth and inhibition, but also proposes a specific mechanism for reduced neural connectivity in the presence of amyloid-β peptides, along with potential intervention points to restore neurite growth. Thereby, we aim to establish a culture system that has the potential to serve as an assay for measuring preclinical, predictive outcomes of drugs and their ability to promote neurite outgrowth, both generally and in a patient-specific manner.

PPM1D ameliorates Alzheimer's disease by promoting mitophagy

Mitochondrial autophagy (mitophagy) plays an essential role in the maintenance of mitochondrial homeostasis. Defective mitophagy triggered by amyloid beta (Aβ) is linked to neuronal deterioration and neurodegeneration in Alzheimer's disease (AD). However, the molecular mechanism underlying the defective mitophagy in AD is still not fully illustrated. Protein phosphatase Mn2+/Mg2+-dependent 1D (PPM1D) triggers autophagy in mouse embryonic fibroblasts. Downregulated PPM1D was shown in the hippocampus of APP/PS1 mice. This study aims to investigate the role of PPM1D in the progression of AD. Here, APP/PS1 mice were used to mimic AD, and rAAV2 vectors expressing PPM1D were injected into the bilateral hippocampus. In vitro, the mouse hippocampal neuron cell line HT22 was stimulated by Aβ1-42 to trigger neuronal damage. High PPM1D expression alleviated the impairments of spatial cognition and memory in APP/PS1 mice. Additionally, PPM1D enhanced autophagosome formation, lysosomal degradation of impaired mitochondria, amyloid plaque deposition, and neuronal degeneration and apoptosis in the hippocampus of APP/PS1 mice. Similar effects of PPM1D on neuronal apoptosis and mitophagy were observed in Aβ1-42-treated HT22 cells, and the effects could be reversed by the mitophagy inhibitor cyclosporine A. In conclusion, PPM1D facilitates mitophagy to inhibit the progression of AD-like disease. Taken together, the present work uncovers defective mitophagy in AD may be associated with down-regulated PPM1D, and PPM1D may be a potential therapeutic target for AD treatment.

Neuroprotective effects of empagliflozin against scopolamine-induced memory impairment and oxidative stress in rats

Alzheimer's disease (AD) is one of the most common age-related neurodegenerative disorders. The main medicinal theory for the management of AD belongs to the acetyl-cholinesterase-inhibition pathway and NMDA antagonism. Recent investigation proposed memory improvement by sodium-glucose co-transporter 2 (SGLT2) inhibitors which indicated to improve glycemic control in adults with type 2 diabetes mellitus. According to the lack of sufficient evidence about the efficacy of empagliflozin (EMPA) for memory improvement, in comparison with donepezil (DON), the present research was carried out in order to investigate this hypothesis towards scopolamine-induced neurotoxicity on experimental male Wistar rats. The animals divided into two sets, each included 4 groups: The first set of Healthy animals [Control, EMPA (4 or 10 mg/kg), DON (1 mg/kg)]. The second set of rat Alzheimer model, which received 2 mg/kg Scopolamine by intraperitoneal route for 10 days followed by other treatments [AD, AD+ EMPA (4 or 10 mg/kg) and AD+DON]. Normal rats and AD rats, with each group receiving different substances for 8 consecutive days and 24 h after the accomplishment of the drug administrations, the memory functions assessed through Morris water maze (MWM) paradigm. This task was followed by decapitation of rats in order to evaluate the biochemical oxidative stress parameters in brain tissue. Our data indicated that EMPA significantly improved animals' performance in the behavioral test with a significant decrease in oxidative stress and antioxidant imbalance. In addition, EMPA (4 mg/kg) significantly reduced both cellular malondialdehyde and protein carbonyl content while conversely increased the total reduced glutathione content. Besides, the levels of total as well as endogenous antioxidants in the ferric reducing antioxidant power assay reported to be augmented. It seems that EMPA significantly improved both cellular biochemical aspects and memory performance in animal models in accordance with histopathological assessments. Conclusively, 4 mg/kg EMPA demonstrated better results in all aspects that were evaluated during this research.

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.

Towards a better diagnosis and treatment of dementia: Identifying common and distinct neuropathological mechanisms in Alzheimer's and vascular dementia

Alzheimer's disease (AD) and vascular dementia (VaD) together contribute to almost 90 % of all dementia cases leading to major health challenges of our time with a substantial global socioeconomic burden. While in AD, the improved understanding of Amyloid beta (Aß) mismetabolism and tau hyperphosphorylation as pathophysiological hallmarks has led to significant clinical breakthroughs, similar advances in VaD are lacking. After comparing the clinical presentation, including risk factors, disease patterns, course of diseases and further diagnostic parameters for both forms of dementia, we highlight the importance of shared pathomechanisms found in AD and VaD: Endothelial damage, blood brain barrier (BBB) breakdown and hypoperfusion inducing oxidative stress and inflammation and thus trophic uncoupling in the neurovascular unit. A dysfunctional endothelium and BBB lead to the accumulation of neurotoxic molecules and Aß through impaired clearance, which in turn leads to neurodegeneration. In this context we discuss possible neuropathological parameters, which might serve as biomarkers and thus improve diagnostic accuracy or reveal targets for novel therapeutic strategies for both forms of dementia.

Basic approach on the protective effects of hesperidin and naringin in Alzheimer's disease

OBJECTIVES

Alzheimer's disease (AD) is a neurodegenerative disease characterized by cognitive impairment. This situation imposes a great burden on individuals, both economically and socially. Today, an effective method for treating the disease and protective approach to tau accumulation has not been developed yet. Studies have been conducted on the effects of hesperidin and naringin flavonoids found in citrus fruits on many diseases.

METHODS

In this review, the pathophysiology of AD is defined, and the effects of hesperidin and naringin on these factors are summarized.

RESULTS

Studies have shown that both components may potentially affect AD due to their antioxidative and anti-inflammatory properties. Based on these effects of the components, it has been shown that they may have ameliorative effects on Aβ, α-synuclein aggregation, tau pathology, and cognitive functions in the pathophysiology of AD.

DISCUSSION

There are studies suggesting that hesperidin and naringin may be effective in the prevention/treatment of AD. When these studies are examined, it is seen that more studies should be conducted on the subject.

Lecanemab-Associated Amyloid-β Protofibril in Cerebrospinal Fluid Correlates with Biomarkers of Neurodegeneration in Alzheimer's Disease

OBJECTIVE

The Clarity AD phase III trial showed that lecanemab reduced amyloid markers in early Alzheimer's disease (AD) and resulted in less decline on measures of cognition and function than placebo. Herein, we aimed to characterize amyloid-β (Aβ) protofibril (PF) captured by lecanemab in human cerebrospinal fluid (CSF) from living participants with different stages in AD, which enable an enhanced understanding of the dynamic changes of lecanemab-associated Aβ-PF (Lec-PF) in vivo.

METHODS

We newly developed a unique and highly sensitive immunoassay method using lecanemab that selectively captures Lec-PF. The CSF level of Lec-PF, Aβ42, Aβ40, p-tau181, p-tau 217, total tau, and neurogranin were measured in Japanese participants (n = 163). The participants in this study consisted of 48 cognitively unimpaired Aβ-negative (CU-), 8 cognitively impaired diagnosed as suspected non-Alzheimer's disease pathophysiology, 9 cognitively unimpaired Aβ-positive (CU+), 34 Aβ-positive with mild cognitive impairment (MCI+), and 64 Aβ-positive with AD dementia (AD+).

RESULTS

The CSF Lec-PF levels significantly increased in the groups of MCI+ and AD+ compared with CU- group. Notably, CSF Lec-PF showed modest correlation with plaque-associated biomarkers in Aβ-positive participants and stronger correlation with neurodegeneration biomarkers, such as CSF total tau and neurogranin, suggesting that CSF Lec-PF levels proximally reflect neurodegeneration as well as the amount of senile amyloid plaques.

INTERPRETATION

This is the first report describing Aβ-PF species captured by lecanemab in human CSF and supporting that Lec-PF is correlated with neurodegeneration in AD and may explain the mechanism of the clinical effect of lecanemab. ANN NEUROL 2025;97:993-1006.

Gastrointestinal Dysfunction and Low-Grade Inflammation Associate With Enteric Neuronal Amyloid-β in a Model for Amyloid Pathology

BACKGROUND

Patients suffering from Alzheimer's disease, a progressive neurodegenerative disorder involving cognitive decline and memory impairment, often present with gastrointestinal comorbidities. Accumulating data also indicate that alterations in the gut can modulate Alzheimer's disease pathology, highlighting the need to better understand the link between gastrointestinal abnormalities and neurodegeneration in the brain.

METHODS

To disentangle the pathophysiology of gastrointestinal dysfunction in Alzheimer's disease, we conducted a detailed pathological characterization of the gastrointestinal tract of 5xFAD mice by performing histological analyses, gene expression studies, immunofluorescence labeling and gut function assays.

RESULTS

We found that 5xFAD mice have elevated levels of intestinal amyloid precursor protein and accumulate amyloid-β in enteric neurons. Histopathology revealed that this is associated with mild intestinal inflammation and fibrosis and accompanied by increased expression of proinflammatory cytokines. While overall enteric nervous system composition and organization appeared unaffected, 5xFAD mice have faster gastrointestinal transit.

CONCLUSION

Our findings indicate that amyloid-β accumulation in enteric neurons is associated with low-grade intestinal inflammation and altered motility and suggest that peripheral pathology may cause gastrointestinal dysfunction in Alzheimer's disease patients.

Common Variants in PLXNA4 and Correlation to Neuroimaging Phenotypes in Healthy, Mild Cognitive Impairment, and Alzheimer's Disease Cohorts

A comprehensive genome-wide association study (GWAS) has validated the identification of the Plexin-A 4 (PLXNA4) gene as a novel susceptibility factor for Alzheimer's disease (AD). Nonetheless, the precise role of PLXNA4 gene polymorphisms in the pathophysiology of AD remains to be established. Consequently, this study is aimed at exploring the relationship between PLXNA4 gene polymorphisms and neuroimaging phenotypes intimately linked to AD. This study encompassed 812 subjects with PLXNA4 genotype data, procured from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Employing a tagging strategy, we identified five common variant sites within the PLXNA4 gene and assessed their associations with glucose metabolism, atrophy in AD-related brain regions (including the medial temporal lobe, hippocampus, and parahippocampal gyrus), and intracerebral Aβ deposition. We conducted a comprehensive analysis using a multiple linear regression model, with neuroimaging phenotypes as the dependent variable and PLXNA4 gene polymorphisms as the independent variable while incorporating APOE e4 carrier status, education level, age, and gender as covariates. The subjects were stratified into three groups based on their disease status: the Alzheimer's disease (AD) group, the mild cognitive impairment (MCI) group, and the cognitively normal healthy control (CN) group. Within each group, we examined the associations between PLXNA4 gene polymorphisms and various neuroimaging phenotypes. Our study identified significant associations between the rs156676-A and rs78036292-G alleles and the baseline volumes of the anterior cingulate and middle temporal gyrus, respectively, across the entire population. After 1 year of follow-up, a significant correlation was observed between the rs6467431-G allele and accelerated volumetric atrophy of the parahippocampal gyrus in the overall population. Additionally, at the 2-year follow-up, significant correlations were observed between three PLXNA4 loci (rs1863015, rs6467431, rs67468325) and volumetric atrophy in the anterior cingulate, middle temporal gyrus, and hippocampus across the entire population. Specifically, the rs1863015-G allele notably accelerated atrophy of the left middle temporal gyrus and bilateral hippocampus, whereas the A alleles of rs6467431 and rs67468325 markedly accelerated atrophy specifically in the bilateral hippocampus. Subgroup analysis further validated these findings. Additionally, in the baseline CN group, the rs78036292 allele showed a significant correlation with intracerebral Aβ deposition, while in the 2-year follow-up CN group, rs67468325 was significantly associated with alterations in glucose metabolism rates in the right cingulate gyrus. Our findings indicate that PLXNA4 genotypes may modulate the development of AD through their regulation of intracerebral Aβ deposition. Additionally, PLXNA4 genotypes are strongly associated with AD-related brain atrophy and glucose metabolism, suggesting that they may alter susceptibility to AD by modulating neurodegenerative biomarkers.

The nuclear-mitochondrial crosstalk in aging: From mechanisms to therapeutics

Aging is a complex physiological process characterized by an irreversible decline in tissue and cellular functions, accompanied by an increased risk of age-related diseases, including neurodegenerative, cardiovascular, and metabolic disorders. Central to this process are epigenetic modifications, particularly DNA methylation, which regulate gene expression and contribute to aging-related epigenetic drift. This drift is characterized by global hypomethylation and localized hypermethylation, impacting genomic stability and cellular homeostasis. Simultaneously, mitochondrial dysfunction, a hallmark of aging, manifests as impaired oxidative phosphorylation, excessive reactive oxygen species production, and mitochondrial DNA mutations, driving oxidative stress and cellular senescence. Emerging evidence highlights a bidirectional interplay between epigenetics and mitochondrial function. DNA methylation modulates the expression of nuclear genes governing mitochondrial biogenesis and quality control, while mitochondrial metabolites, such as acetyl-CoA and S-adenosylmethionine, reciprocally influence epigenetic landscapes. This review delves into the intricate nuclear-mitochondrial crosstalk, emphasizing its role in aging-related diseases and exploring therapeutic avenues targeting these interconnected pathways to counteract aging and promote health span extension.

The ER protein CANX (calnexin)-mediated autophagy protects against alzheimer disease

Although the relationship between macroautophagy/autophagy and Alzheimer disease (AD) is widely studied, the underlying mechanisms are poorly understood, especially the regulatory role of the initiation signaling of autophagy on AD. Here, we find that the ER transmembrane protein CANX (calnexin) is a novel interaction partner of the autophagy-inducing kinase ULK1 and is required for ULK1 recruitment to the ER under basal or starved conditions. Loss of CANX results in the inactivity of ULK1 kinase and inhibits autophagy flux. In the brains of people with AD and APP-PSEN1 mice, the interaction of CANX and ULK1 declines. In mice, the lack of CANX in hippocampal neurons causes the accumulation of autophagy receptors and neuron damage, which affects the cognitive function of C57BL/6 mice. Conversely, overexpression of CANX in hippocampal neurons enhances autophagy flux and partially contributes to improving cognitive function of APP-PSEN1 mice, but not the CANX variant lacking the interaction domain with ULK1. These findings reveal a novel role of CANX in autophagy activity and cognitive function by cooperating with ULK1.Abbreviation: AD: Alzheimer disease; APEX: ascorbate peroxidase; APP: amyloid beta precursor protein; APP-PSEN1 mice: amyloid beta precursor protein-presenilin 1 transgenic mice; ATG: autophagy related; Aβ: amyloid-β; BiFC: bimolecular fluorescence complementation; CANX: calnexin; EBSS: Earle's balanced salt solution; EM: electron microscopy; IP: immunopurification; KO: knockout; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MWM: Morris water maze; PLA: proximity ligation assay; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol-3-phosphate; SQSTM1/p62, sequestosome 1.

APOE deficiency inhibits amyloid-facilitated (A) tau pathology (T) and neurodegeneration (N), halting progressive ATN pathology in a preclinical model

In AD, amyloid pathology (A) precedes progressive development of tau pathology (T) and neurodegeneration (N), with the latter (T/N) processes associated with symptom progression. Recent anti-amyloid beta (Aβ) clinical trials raise hope but indicate the need for multi-targeted therapies, to effectively halt clinical AD and ATN pathology progression. APOE-related putative protective mutations (including APOE3Christchurch, RELN-COLBOS) were recently identified in case reports with exceptionally high resilience to autosomal dominant AD. In these cases, Nature provided proof of concept for halting autosomal dominant AD and ATN progression in humans, despite a high amyloid load, and pointing to the APOE pathway as a potential target. This is further supported by the recent identification of APOE4 homozygosity as genetic AD. Here we studied the role of APOE in a preclinical model that robustly mimics amyloid-facilitated (A) tau pathology (T) and subsequent neurodegeneration (N), denoted as ATN model, generated by crossing 5xFAD (F +) and TauP301S (T +) mice. We show that APOE deficiency, markedly inhibited progression to tau pathology and tau-induced neurodegeneration in this ATN model, despite a high Aβ load, reminiscent of the high resilience ADAD case reports. Further study identified, despite increased Aβ load (W02 stained), a significant decrease in compacted, dense core plaques stained by ThioS in APOE deficient ATN mice. Furthermore, single-cell RNA sequencing (scRNA-seq) showed a crucial role of APOE in microglial conversion beyond homeostatic microglia to reactive and disease associated microglia (DAM) in this ATN preclinical model. Microglial elimination significantly decreased amyloid-driven tau pathology, in the presence of APOE, but not in APOE deficient mice. Together the data demonstrate that APOE deficiency inhibits amyloid-driven tau pathology and subsequent neurodegeneration, by pleiotropic effects including prevention of dense core plaque formation and halting conversion of homeostatic microglia. We here present a model recapitulating inhibition of amyloid-facilitated tau pathology by APOE deficiency despite high Aβ load, important for understanding the role of APOE, and APOE-dependent processes in ATN progression and its therapeutic exploitation in AD.

Functional Specificity of Astrocyte Subtypes in Alzheimer's Disease: Decoding Disease Mechanisms Through Network-based Analysis of Integrated Single-Nuclei Multi-Omic Data

Alzheimer's disease (AD) is the most common cause of dementia. Recent studies have revealed incontrovertible roles of astrocytes in the pathology of AD. Considering the conflicting behaviours of astrocytes in AD brain, they have been proposed to have subtypes. In this study, astrocytes from two publicly available single-nuclei transcriptome datasets were integrated to provide in-depth characterization of astrocyte subtypes in AD. Differentially expressed genes within each astrocyte subtype were analyzed by mapping them onto a human protein-protein interaction network to discover subnetworks with biologically relevant genes. Integrating single-nuclei datasets and using network-based analysis approach led to higher sensitivity in capturing AD-related genes compared to traditional approaches. One of the identified subtypes was highly representative of neurotoxic reactive astrocytes in AD. The results show that A1 reactive astrocytes could have an enhancing role for the amyloid beta and neurofibrillary tangle accumulation through MAPK10, MAPT, and TMED10, which were all found to be differentially expressed in this subtype during AD in our analysis. Moreover, single-nuclei ATAC-Seq data from the same tissue was re-analyzed to evaluate astrocyte subtypes at multi-omic level. It was found that astrocyte subtypes underwent epigenetic reprogramming during AD. Potential transcription factors were also identified for the regulation of the genes that exhibited alterations in both promoter accessibility and gene expression in AD. Comparative analysis of single-nuclei RNA-Seq and ATAC-Seq datasets showed that PTN gene, which was reported to be important for AD pathology, is likely regulated by ATF3 transcription factor in subtype-specific manner in astrocytes.

Targeting hypoxia-related pathobiology in Alzheimer's disease: strategies for prevention and treatment

INTRODUCTION

Alzheimer's Disease (AD) is a neurodegenerative condition characterised by cognitive decline and memory impairment. Recent research highlights the important role of hypoxia, a state of insufficient oxygen availability, in exacerbating AD pathogenesis.

MATERIALS AND METHODS

Through the use of a number of different search engines like Scopus, PubMed, Bentham, and Elsevier databases, a literature review was carried out for investigating the role of hypoxia mediated pathobiology in AD. Only peerreviewed articles published in reputable journals in English language were included. Conversely, non-peer-reviewed articles, conference abstracts, and editorials were excluded, along with studies lacking experimental or clinical relevance or those unavailable in full text.

CONCLUSION

Hypoxia exacerbates core pathological features such as oxidative stress, neuroinflammation, mitochondrial dysfunction, amyloid-beta (Aβ) dysregulation, and hyperphosphorylation of tau protein. These interlinked mechanisms establish a self-perpetuating cycle of neuronal damage, accelerating disease progression. Addressing hypoxia as a modifiable risk factor offers potential for both prevention and treatment of AD. Exploring hypoxia and the HIF signalling pathway may help counteract the neuropathological and symptomatic effects of neurodegeneration.

Glial changes and gene expression in Alzheimer's disease from snRNA-Seq and spatial transcriptomics

BackgroundAlzheimer's disease (AD) is characterized by cortical atrophy, glutamatergic neuron loss, and cognitive decline. However, large-scale quantitative assessments of cellular changes during AD pathology remain scarce.ObjectiveThis study aims to integrate single-nuclei sequencing data from the Seattle Alzheimer's Disease Cortical Atlas (SEA-AD) with spatial transcriptomics to quantify cellular changes in the prefrontal cortex and temporal gyrus, regions vulnerable to AD neuropathological changes (ADNC).MethodsWe mapped differentially expressed genes (DEGs) and analyzed their interactions with pathological factors such as APOE expression and Lewy bodies. Cellular proportions were assessed, focusing on neurons, glial cells, and immune cells.ResultsRORB-expressing L4-like neurons, though vulnerable to ADNC, exhibited stable cell numbers throughout disease progression. In contrast, astrocytes displayed increased reactivity, with upregulated cytokine signaling and oxidative stress responses, suggesting a role in neuroinflammation. A reduction in synaptic maintenance pathways indicated a decline in astrocytic support functions. Microglia showed heightened immune surveillance and phagocytic activity, indicating their role in maintaining cortical homeostasis.ConclusionsThe study underscores the critical roles of glial cells, particularly astrocytes and microglia, in AD progression. These findings contribute to a better understanding of cellular dynamics and may inform therapeutic strategies targeting glial cell function in AD.

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.

Tau aggregation induces cell death in iPSC-derived neurons

Abnormal accumulation of tau proteins in the brain is a hallmark of neurodegenerative diseases such as Alzheimer's disease and is closely linked with neuronal cell death. Tau accumulation is a prominent therapeutic target for Alzheimer's disease, since tau accumulation correlates well with the disease progression, and tau-targeting drugs hold potentials to halt the disease progression. Given the differential response of human and mouse neuronal cells, there is a critical need for a human cellular platform to quickly screen for tau-related neurodegenerative disease therapeutics. However, inducing rapid, tau-dependent neuronal cell death in human models remains challenging. In this study, we established a human cellular model capable of inducing tau aggregation-dependent neuronal cell death within two weeks via tau overexpression. Additionally, we demonstrated the neuroprotective efficacy of known tau-targeting compounds within this system. These findings suggest that our cellular model recapitulates the molecular pathogenesis of tau-induced neurodegeneration and could serve as a valuable platform for drug screening in tauopathies.

Baseline habitual dietary nitrate intake and Alzheimer's Disease related neuroimaging biomarkers in the Australian Imaging, Biomarkers and Lifestyle study of ageing

BACKGROUND

Dietary nitrate, as a nitric oxide (NO) precursor, may support brain health and protect against dementia.

OBJECTIVE

Our primary aim was to investigate whether dietary nitrate is associated with neuroimaging markers of brain health linked with Alzheimer's disease (AD).

PARTICIPANTS

Study participants were cognitively unimpaired individuals from the Australian Imaging, Biomarkers and Lifestyle Study of Ageing (AIBL) who had β-amyloid positron emission tomography (PET) scans (n = 554) and magnetic resonance imaging (MRI) scans (n = 335) and had completed a Food Frequency Questionnaire at baseline.

METHODS

Source-specific nitrate intakes were estimated using comprehensive nitrate food composition databases. Rates of cerebral β-amyloid (Aβ) deposition, measured using PET, and rates of brain atrophy, measured using MRI, were assessed between baseline and 126-months follow-up, at intervals of 18 months. Multivariable-adjusted linear mixed effect models were used to examine associations between baseline source-specific nitrate intake and rates of (i) cerebral Aβ deposition and (ii) brain atrophy, over the 126 months of follow-up. Analyses were carried out following stratification of the sample by established dementia Alzheimer's disease (AD) risk factors including sex and presence or absence of the apolipoprotein E (APOE) ε4 allele.

RESULTS

In women carriers of the APOE ε4 allele, higher plant sourced nitrate intake (median intake 121 mg/day), was associated with a slower rate of cerebral Aβ deposition [β: 4.47 versus 8.99 Centiloid (CL) /18 months, p < 0.05] and right hippocampal atrophy [-0.01 versus -0.03 mm3 /18 months, p < 0.01], after multivariable adjustments. Moderate intake showed protective associations in men carriers and in both men and women non-carriers of APOE ε4.

CONCLUSIONS

Associations were observed between plant-derived nitrate intake and cerebral Aβ deposition, particularly in high-risk populations (women and APOE ε4 carriers). Associations were also observed for brain volume atrophy, however these exhibited subgroup variability without clear patterns relative to sex and APOE ε4 allele carriage. These findings suggest a potential link between plant-sourced nitrate and AD related neuroimaging markers of brain health improved brain health, but further validation in larger studies is required.

Novel Phenoselenazines as Amyloid-β Aggregation Inhibitors

A novel library of N-benzylphenoselenazine derivatives 8a-j were designed, synthesized, and evaluated as inhibitors of amyloid-beta (Aβ42) aggregation. In the thioflavin T-based fluorescence aggregation kinetics assay, compounds 8i and 8j exhibited excellent inhibition of Aβ42 aggregation (∼91% inhibition at 25 μM), and the activity was comparable to that of reference agents resveratrol (∼88%) and methylene blue (∼95% inhibition). Both compounds also demonstrated Aβ42 disaggregation properties (58% and 76% respectively at 25 μM) and antioxidant activity (80.5% and 59% respectively at 25 μM). In the cell culture studies, both 8i and 8j were able to reduce Aβ42-mediated cytotoxicity. Computational studies suggest that these compounds interact in a narrow channel formed by the N- and C-termini in the Aβ42 pentamer model to stabilize the assembly and prevent further aggregation. These results demonstrate the viability of the N-benzylphenoselenazines as promising candidates to target the amyloid cascade in Alzheimer's disease.

Intranasal insulin in Alzheimer disease (diabetes in situ?): a systematic review and meta-analysis

Alzheimer disease (AD) is a neurodegenerative disorder. Evidence suggests that AD shares pathophysiological similarities with type 2 diabetes. Intranasal insulin (INI) has emerged as a potential therapeutic approach for AD by directly targeting the brain and modulating insulin signaling pathways.

Objective

To evaluate the efficacy and safety of INI therapy for AD through a systematic review and meta-analysis of randomized controlled trials.

Methods

A search of electronic databases, including PubMed, Web of Science, Scopus, and Embase, was conducted to identify relevant studies published up to June 2024. Inclusion criteria encompassed peer-reviewed original research articles focused on humans, investigating the therapeutic effects of INI administration on cognitive impairment associated with AD, and reporting quantitative data on cognitive outcomes, biomarkers, or pathological markers relevant to AD. A meta-analysis was conducted to quantitatively synthesize the effects of INI on cognitive outcomes.

Results

A total of 647 articles were identified, and eight studies met the inclusion criteria. The overall odds ratio was 3.75 (95%CI 1.49-9.40). The test for overall effect showed a statistically significant difference (p<0.05). However, the I2 value indicated a high level of heterogeneity (85.5%), suggesting significant variability among the studies.

Conclusion

While the current data is not yet conclusive enough to definitively establish INI as a standard treatment for AD, the evidence supporting its safety, efficacy, and reduced risk of systemic side effects suggests potential cognitive benefits for improving global cognition in patients with AD.

A Brain-Penetrating Foldamer Rescues Aβ Aggregation-Associated Alzheimer's Disease Phenotypes in In Vivo Models

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is the leading cause of dementia, affecting nearly 55 million people across the world. One of the central pathological factors associated with AD is the aggregation of Aβ42, a peptide product cleaved through pathological processes in AD. Under pathological conditions, Aβ42 aggregates into insoluble plaques in the brain and impairs the function of neurons, which contributes to the cognitive decline associated with AD. Therefore, the modulation of Aβ42 aggregation is considered a potential therapeutic intervention for AD. Using an Oligoquinoline-based foldamer library, we have identified a potent foldamer antagonist (SK-131) of Aβ42 aggregation. SK-131 inhibits the aggregation by inducing a α-helical structure in monomeric Aβ42. Here, we demonstrated that SK-131 rescues Aβ42 aggregation-associated phenotypes in AD cellular and multiple Caenorhabditis elegans AD models, including intracellular inhibition of Aβ42 aggregation, rescue of behavioral deficits, and attenuation of reactive oxygen species. It efficiently crosses the blood-brain barrier and demonstrates favorable pharmaceutical properties. It also potently inhibits Zn2+-mediated Aβ42 aggregation by potentially displacing Zn2+ from Aβ42. In summary, we have identified a potent brain-penetrating foldamer that efficiently rescues AD phenotypes in in vivo models. Unlike most of the therapeutic approaches that target Aβ aggregates, we have identified and validated a novel therapeutic pathway by inducing structural change in Aβ and rescuing AD phenotypes in in vivo models. This study will further aid in the quest to identify lead therapeutics to slow or stop the progression of AD.

Identification and Characterization of the Structure and Size of Aβ42 Oligomers Targeting the Receptor FcγRIIb

Kam and colleagues discovered that FcγRIIb can specifically bind to Aβ42 oligomers (AβOs). The N-terminal residues F4 and D7 of Aβ42, as well as the W115 residue in domain D2 of FcγRIIb, are involved in this binding. However, the specificity of the FcγRIIb receptor's binding sites for AβOs and their dependence on different AβO species, including dimers (D/DT), trimers (T/TT), tetramers (Te/TeT), and pentamers (P/PT) during both the primary (P1) and secondary nucleation phases (P2), remains unknown. To address this, we employed molecular dynamics (MD) simulations to investigate the interactions between the extracellular domains D1 and D2 (FDD) of FcγRIIb and AβOs of varying sizes in the two different phases. We discovered that three specific fragments (f1, f2, and f3) of domain D2 in FDD are the primary binding sites for AβO species. Furthermore, among AβOs of the same molecular weight, those from the P2 phase exhibit a stronger binding affinity for FDD than those from the P1 phase. The distinction is ascribed to the stronger dependence on the hydrophobic residues in the β1 and β2 regions for the binding of AβOs in P2 (including TT, TeT, and PT) than that (including D, Te, and P) in the P1 phase. In the P1 phase, these AβOs prefer to achieve binding to FDD through their N-terminal residues; however, by this, we identified that the species observed in Kam's experiment to bind FcγRIIb should probably be the tetrameric AβO (Te) in the P1 phase. Moreover, within both the P1 and P2 phases, we predicted that the trimeric AβO species in either the P1 or P2 phase is the strongest binding ligand for the FcγRIIb receptor. This study provides a comprehensive molecular perspective on the interaction between FcγRIIb and AβO in P2, which is of significant importance for the development of therapeutic strategies targeting Alzheimer's disease (AD) and autoimmune diseases.

Morphological and Molecular Profiling of Amyloid-β Species in Alzheimer's Pathogenesis

Alzheimer's disease (AD) is the most common form of dementia around the world (~ 65%). Here, we portray the neuropathology of AD, biomarkers, and classification of amyloid plaques (diffuse, non-cored, dense core, compact). Tau pathology and its involvement with Aβ plaques and cell death are discussed. Amyloid cascade hypotheses, aggregation mechanisms, and molecular species formed in vitro and in vivo (on- and off-pathways) are described. Aβ42/Aβ40 monomers, dimers, trimers, Aβ-derived diffusible ligands, globulomers, dodecamers, amylospheroids, amorphous aggregates, protofibrils, fibrils, and plaques are characterized (structure, size, morphology, solubility, toxicity, mechanistic steps). An update on AD-approved drugs by regulatory agencies, along with new Aβ-based therapies, is presented. Beyond prescribing Aβ plaque disruptors, cholinergic agonists, or NMDA receptor antagonists, other therapeutic strategies (RNAi, glutaminyl cyclase inhibitors, monoclonal antibodies, secretase modulators, Aβ aggregation inhibitors, and anti-amyloid vaccines) are already under clinical trials. New drug discovery approaches based on "designed multiple ligands", "hybrid molecules", or "multitarget-directed ligands" are also being put forward and may contribute to tackling this highly debilitating and fatal form of human dementia.

Potential benefits of marine-derived compounds for slowing the advancement of Alzheimer's disease

The incidence of Alzheimer's is increasing and poses a significant social and economic burden. The pathogenesis involved in the expansion of AD includes neuronal oxidative damage, tau phosphorylation, amyloid beta aggregation, neuroinflammation, etc. Despite enormous efforts, there is currently no effective treatment or cure for this condition in the allopathic system. Marine compounds are appealing options and have a strong neuroprotective impact. Marine-derived compounds from sponges, algae, and marine invertebrates can be used for neuroprotection, with fewer adverse effects than synthetic drugs. Various compounds such as bryostatin-1, docosahexaenoic acid, spirolides, and astaxanthin, GV-971, have demonstrated outstanding activity and bioavailability.

Utilization of precision medicine digital twins for drug discovery in Alzheimer's disease

Alzheimer's disease (AD) presents significant challenges in drug discovery and development due to its complex and poorly understood pathology and etiology. Digital twins (DTs) are recently developed virtual real-time representations of physical entities that enable rapid assessment of the bidirectional interaction between the virtual and physical domains. With recent advances in artificial intelligence (AI) and the growing accumulation of multi-omics and clinical data, application of DTs in healthcare is gaining traction. Digital twin technology, in the form of multiscale virtual models of patients or organ systems, can track health status in real time with continuous feedback, thereby driving model updates that enhance clinical decision-making. Here, we posit an additional role for DTs in drug discovery, with particular utility for complex diseases like AD. In this review, we discuss salient challenges in AD drug development, including complex disease pathology and comorbidities, difficulty in early diagnosis, and the current high failure rate of clinical trials. We also review DTs and discuss potential applications for predicting AD progression, discovering biomarkers, identifying new drug targets and opportunities for drug repurposing, facilitating clinical trials, and advancing precision medicine. Despite significant hurdles in this area, such as integration and standardization of dynamic medical data and issues of data security and privacy, DTs represent a promising approach for revolutionizing drug discovery in AD.

Pathological Characterisation of Posterior Cortical Atrophy in Comparison With Amnestic Alzheimer's Disease

AIMS

Posterior cortical atrophy (PCA) is a predominantly young-onset neurodegenerative syndrome, typically caused by Alzheimer's disease (PCA-AD). PCA-AD presents with visual and spatial dysfunction attributed to occipito-parietal or 'posterior' brain regions rather than memory difficulties characteristic of typical amnestic-led Alzheimer's disease (a-AD) attributed to medial temporal regions. Imaging and neuropathological studies suggest that PCA-AD is associated with a more posterior distribution of tau neurofibrillary tangles (NFTs), whereas β-amyloid pathology (Aβ) is diffusely deposited throughout the cortex. This study characterised the neuropathological substrates of PCA-AD in comparison with a-AD, to further understanding of the biological basis of phenotypical heterogeneity in AD.

METHODS

Immunohistochemistry for Aβ; tau; the microglial markers CD68, CR3-43 and Iba1; α-synuclein; and TDP-43 was carried out on 26 PCA-AD and 27 age and gender-matched a-AD cases at the Queen Square Brain Bank. Aβ, tau and the three microglial markers were quantified in the superior frontal, superior temporal, superior parietal and occipital (primary visual cortex) cortices, with α-synuclein and TDP-43 assessed using formal staging criteria. In addition, microglial circularity, a morphological indicator of microglial activation state, was calculated.

RESULTS

There was a higher load of Aβ and tau in the parietal region of PCA-AD compared to a-AD. In the PCA-AD compared to the a-AD group, there were significant increases in tau load in parietal and frontal relative to temporal regions. There was no difference in cerebral amyloid angiopathy (CAA) severity between PCA-AD and a-AD. There was a significantly lower temporal CD68 load in a-AD compared with PCA-AD. In a-AD, CD68 load was lowest and tau load highest in the temporal relative to all other regions.

CONCLUSIONS

This study demonstrates differences in the distribution of Aβ and tau and variations in regional neuroinflammatory response in PCA-AD and a-AD. These findings extend our understanding of the biological substrates underpinning PCA-AD and highlight the potential for exploring phenotypic variants to understand selective vulnerability in neurodegenerative diseases.

Perivascular brain clearance as a therapeutic target in cerebral amyloid angiopathy and Alzheimer's disease

Although distinct diseases, both cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD) are characterized by the aggregation and accumulation of amyloid-β (Aβ). This is thought to be due, in part, to impaired perivascular Aβ clearance from the brain. This shared failure in both diseases presents a common opportunity for therapeutic intervention. In this review we discuss the idea that promoting perivascular brain clearance could be an effective strategy for safely reducing Aβ levels in CAA and AD thereby improving clinical outcomes, most notably hemorrhagic stroke and cognitive decline. We will explore the evidence for the different forces that are thought to drive perivascular brain clearance, review the literature on potential strategies for potentiating these driving forces, and finally we will discuss the substantial translational challenges and considerations that would accompany such an intervention.

Current amyloid inhibitors: Therapeutic applications and nanomaterial-based innovations

Amyloid proteins have long been in the spotlight for being involved in many degenerative diseases including Alzheimer´s, Parkinson´s or type 2 diabetes, which currently cannot be prevented and for which there is no effective treatment or cure. Here we provide a comprehensive review of inhibitors that act directly on the amyloidogenic pathway (at the monomer, oligomer or fibril level) of key pathological amyloids, focusing on the most representative amyloid-related diseases. We discuss the latest advances in preclinical and clinical trials, focusing on cutting-edge developments, particularly on nanomaterials-based inhibitors, which offer unprecedented opportunities to address the complexity of protein misfolding disorders and are revolutionizing the landscape of anti-amyloid therapeutics. Notably, nanomaterials are impacting critical areas such as bioavailability, penetrability and functionality of compounds currently used in biomedicine, paving the way for more specific therapeutic solutions tailored to various amyloid-related diseases. Finally, we highlight the window of opportunity opened by comparative analysis with so-called functional amyloids for the development of innovative therapeutic approaches for these devastating diseases.

Associations of moderate alcohol intake with cerebrospinal fluid biomarkers of Alzheimer's disease: data from the ALBION study

PURPOSE

According to a WHO statement, it has been asserted that there is no safe level of alcohol consumption regarding human health. Nevertheless, the relationship between alcohol consumption and Alzheimer's disease (AD) pathology remains unclear. Therefore, we examined whether the frequency and patterns of alcohol consumption could predict neurodegeneration biomarkers in a cohort of middle-aged adults without dementia.

METHODS

A total of 195 participants without dementia were included from the ALBION study. Multivariate logistic regression analyses were conducted using drinking frequency subgroups (abstainers, occasional drinkers, and light-to-moderate drinkers) and Mediterranean-Alcohol Dietary Pattern (MADP) adherence subgroups along with cerebrospinal fluid (CSF) AD biomarkers (Tau, phosphorylated tau (PTau) and amyloid beta (Aβ). In these analyses, the abstinence was used as the reference category.

RESULTS

Of the 195 individuals without dementia, 66% were female, with an average age of 65 ± 9.4 years, and they had 13.8 ± 3.6 years of education. Logistic regression analyses revealed that light-to-moderate drinkers (n = 51) were associated with higher Aβ positivity [OR: 2.98 (1.29-6.90)] compared to the abstinence (n = 117). Additionally, high adherence to the MADP was significantly associated with higher Aβ, Tau/Aβ42, and PTau/Aβ42 ratios positivity compared to the abstinence.

CONCLUSION

Light-to-moderate alcohol intake was associated with higher Aβ deposition in middle-aged individuals without dementia, compared to abstinence. High adherence to the MADP, which indicates low-to-moderate red wine consumption distributing over the week with meals, was associated with a higher Aβ and Tau/Aβ and PTau/Aβ positivity. Therefore, the management of alcohol consumption may help improve AD outcomes even at the preclinical stage.

Visualizing Intracellular Localization of Natural-Product-Based Chemical Probes Using Click-Correlative Light and Electron Microscopy

Flavonoids such as sterubin and fisetin─and derivatives thereof─show strong neuroprotective effects in vitro as well as in vivo, combined with negligible toxicity and can therefore be considered novel treatment options for neurodegenerative diseases such as Alzheimer's disease. However, their subcellular locations responsible for neuroprotection and exact modes of action still remain unclear. Here, we present chemical probes based on both flavonoids sterubin and fisetin that were utilized in fluorescence microscopy and click-correlative light and electron microscopy to detect and visualize the localization of specific intracellular targets. We successfully adapted the workflow of correlative light and electron microscopy to a click-chemistry-based approach in a murine hippocampal cell line (HT22) on ultrathin resin sections making visualization of a small molecule for the first time possible in this setup. Utilizing this newly adapted technique, we could demonstrate that sterubin and fisetin show specific enrichment in the endoplasmic reticulum.

Multimodal MRI accurately identifies amyloid status in unbalanced cohorts in Alzheimer's disease continuum

Amyloid-β (Aβ) plaques in conjunction with hyperphosphorylated tau proteins in the form of neurofibrillary tangles are the two neuropathological hallmarks of Alzheimer's disease. It is well-known that the identification of individuals with Aβ positivity could enable early diagnosis. In this work, we aim at capturing the Aβ positivity status in an unbalanced cohort enclosing subjects at different disease stages, exploiting the underlying structural and connectivity disease-induced modulations as revealed by structural, functional, and diffusion MRI. Of note, due to the unbalanced cohort, the outcomes may be guided by those factors rather than amyloid accumulation. The partial views provided by each modality are integrated in the model, allowing to take full advantage of their complementarity in encoding the effects of the Aβ accumulation, leading to an accuracy of 0.762 ± 0.04. The specificity of the information brought by each modality is assessed by post hoc explainability analysis (guided backpropagation), highlighting the underlying structural and functional changes. Noteworthy, well-established biomarker key regions related to Aβ deposition could be identified by all modalities, including the hippocampus, thalamus, precuneus, and cingulate gyrus, witnessing in favor of the reliability of the method as well as its potential in shedding light on modality-specific possibly unknown Aβ deposition signatures.

Medial septum deep brain stimulation enhances memory and hippocampal neurogenesis in the D-galactose induced rat model of aging: behavioral and immunohistochemical study

One of the cardinal features of aging is brain aging, which manifests itself in impaired cognitive functions. Experimental data suggest that deep brain stimulation (DBS) can improve memory functions when stimulating specific brain regions. In present study we tested the hypothesis that medial septum (MS) DBS enhances memory function by modulating the hippocampal neurogenesis in the D-galactose (D-gal) induced rat model of aging. Rats were randomly assigned to four experimental groups: (1) control, (2) administration of D-gal, (3) administration of D-gal and electrode implantation and (4) administration of D-gal, electrode implantation and stimulation. Our results showed that MS DBS significantly enhanced the memory functions in an animal model of aging induced by D-gal administration, which impaired long-term spatial memory in the Morris water maze and impaired spatial and object novelty recognition memory in the open field. The immunohistochemical studies showed that in the Dentate Gyrus (DG) of rats with D-gal administration or D-gal combined with electrode implantation, the number of NeuN (neuronal nuclear antigen) or Doublecortin-immunopositive cells decreased (Doublecortin - a biomarker for the post-mitotic phase of cells); MS stimulation increases the number of these cells in the DG to levels comparable to the control group. Thus, MS-DBS restores the level of hippocampal neurogenesis. The present data demonstrate for the first time that chronic DBS of the MS restores memory functions in a D-gal-induced animal model of aging, and that one of the important underlying mechanisms is mediated by enhanced neurogenesis in the hippocampus.

Explore peptides extracted from gliadin hydrolysates suppressing BACE1 activity and restraining Aβ protein deposition

Alzheimer's Disease (AD) constitutes approximately 70 % of dementia cases and is the most prevalent form of dementia. Current therapeutic options, including acetylcholinesterase inhibitors and N-methyl d-aspartate (NMDA) receptor antagonists, provide symptomatic relief but do not cure the disease and often come with side effects. The primary pathological features of AD are amyloid plaques and neurofibrillary tangles, with amyloid plaques formed by the abnormal accumulation of Amyloid-β (Aβ). BACE1 (β-site APP-cleaving enzyme 1), a β-secretase, is a key initiator in amyloidosis. Previous research has shown that G-Bro hydrolysate, produced from the bromelain hydrolysis of gliadin, has optimal BACE1 inhibitory efficiency. This study employs G-Bro hydrolysate for nano UHPLC-ESI Q-TOF mass spectrometry to identify peptide fragment sequences and conducts BACE1 inhibition assays to isolate the most effective peptide, VR-peptide. Using the N2a/PS/APP cell model, we explored the impact of chemically synthesized VR-peptide on BACE1 protein expression, the secretion of soluble APP (sAPP), and levels of Aβ and intracellular Aβ1-42. Results demonstrate that VR-peptide achieves a BACE1 inhibitory rate of 63.8 % and reduces BACE1 expression by over 90 % in comparison with untreated N2a/PS/APP cells. It shifts the balance between extracellular Aβ monomers and aggregates, favoring monomer formation and decreasing intracellular Aβ1-42 levels by over 56 %, underscoring its neuroprotective potential. In conclusion, VR-peptide exhibits promise as a BACE1 inhibitor and a preventive agent against Alzheimer's disease. Derived from hydrolyzed cereal foods, it could be effectively paired with a suitable drug delivery system for enhanced neuronal penetration, paving the way for neuroprotective peptide products targeting Alzheimer's disease.

Microglial cGAS Deletion Preserves Intercellular Communication and Alleviates Amyloid-β-Induced Pathogenesis of Alzheimer's Disease

Innate immune activation plays a crucial role in the pathogenesis of Alzheimer's disease (AD) and related dementias (ADRD). The cytosolic DNA sensing pathway, involving cGAMP synthase (cGAS) and Stimulator of Interferon Genes (STING), has emerged as a key mediator of neurodegenerative diseases. However, the precise mechanisms through which cGAS activation influences AD progression remain poorly understood. In this study, we observed significant up-regulation of cGAS-STING signaling pathway in AD. Notably, this increase is primarily attributed to microglia, rather than non-microglial cell types. Using an inducible, microglia-specific cGAS knockout mouse model in the 5xFAD background, we demonstrated that deleting microglial cGAS at the onset of amyloid-β (Aβ) pathology profoundly restricts plaque accumulation and protects mice from Aβ-induced cognitive impairment. Mechanistically, our study revealed cGAS promotes plaque-associated microglia accumulation and is essential for inflammasome activation. Moreover, we showed that restricting cGAS-mediated innate immunity is crucial for preserving inter-cellular communication in the brain and induces pleiotrophin, a neuroprotective factor. These findings offer novel insights into the specific roles of the innate immune system in AD employing a cell-type-specific approach. The conclusions provide a foundation for targeted interventions to modulate the microglial cGAS-STING signaling pathway, offering promising therapeutic strategy for AD treatment.

Evolution of Human Susceptibility to Alzheimer's Disease: A Review of Hypotheses and Comparative Evidence

Primates rely on memory to navigate both physical and social environments and in humans, loss of memory function leads to devastating consequences. Alzheimer's disease (AD) is a neurodegenerative disease which begins by impacting memory functioning and is ultimately fatal. AD is common across human populations and its prevalence is predicted to rise with increases in the aging population. Despite this, the full AD phenotype has not been observed in any other nonhuman primate species. While a significant amount of research has been devoted to understanding the immediate mechanisms involved in AD pathogenesis in humans, less research has focused on why humans are particularly vulnerable to neurodegenerative diseases like AD. Here we explore hypotheses on the evolution of distinct human susceptibility to AD and place these in the context of findings from comparative neuroanatomical and molecular studies and discuss recent evidence for evolutionary changes protective against AD in the primate lineage.

Liver-X receptor β-selective agonist CE9A215 regulates Alzheimer's disease-associated pathology in a 3xTg-AD mouse model

In Alzheimer's disease (AD), tau pathology is closely associated with disease progression. Therefore, therapeutics that alleviate tau pathology are essential. Liver-X receptor (LXR) has garnered interest as a potential target for the treatment of AD. We previously investigated the potent anti-allergic and anti-inflammatory effects of inotodiol, hereafter referred to as CE9A215, in various disease models. In this study, we explored the potential of CE9A215 as a treatment for AD. CE9A215 preferentially activated LXRβ (EC50 <10 nM), with no significant activation observed for LXRα at concentrations up to 1000 nM. Pharmacokinetic analysis confirmed that CE9A215 crosses the blood-brain barrier and accumulates in the brain. Moreover, CE9A215 modulated the expression of ABCA1, APOE, SREBP-1c and AQP4 in the brains of wild-type and LXR α/β knockout mice in LXRβ-dependent manner. The efficacy of CE9A215 on AD-related pathologies was evaluated using 3xTg-AD mice. CE9A215 exerted both prophylactic and therapeutic effects on AD-associated behaviors and pathologies, including reductions in amyloid-β, phosphorylated tau, and neuroinflammation in the hippocampus. Transcriptomic analysis revealed that CE9A215 induced significant changes in genes associated with tau pathology, particularly in pathways related to protein phosphorylation and PI3K/AKT signaling. Our findings suggest that CE9A215 could be a promising therapeutic candidate for AD, particularly in mitigating tau hyperphosphorylation and related AD pathologies.

New low-dose curcumin derivative with therapeutic potential in Alzheimer's disease: Results from an in vitro and in vivo study in mice

Curcumin has been proposed as a potential treatment for Alzheimer's disease (AD) due to its ability to inhibit amyloid-β (Aβ) peptide aggregates and to destabilise pre-formed ones. Derivative 27 was synthesized to improve low-dose efficacy in the context of AD. Its anti-inflammatory, antioxidant and anti-amyloidogenic activities were evaluated in chemico, in vitro using AD and neuroinflammation cell models, and in vivo using the double-transgenic APP/PS1 mice. In vitro, this curcumin derivative significantly reduced nitric oxide (NO) production and levels of pro-inflammatory proteins, inducible NO synthase, pro-interleukin-1β (Pro-IL-1β) and cyclooxygenase-2. Furthermore, Derivative 27 activated nuclear factor erythroid 2-related factor 2 transcription factor (Nrf2) and significantly increased Nrf2 and heme-oxygenase-1 protein levels in the nucleus and in the cytoplasm, respectively. In one-year-old APP/PS1 mice, orally administered-Derivative 27 (50 mg/Kg/day) for 28 days improved spatial short-term memory and significantly decreased hippocampal Pro-IL-1β and amyloid precursor protein levels, as well as Aβ levels in the hippocampus and plasma. This study supports developing new chemical approaches to alter curcumin molecule, enabling lower doses, while increasing the effectiveness in AD treatment.

Alzheimer's disease risk ABCA7 p.A696S variant disturbs the microglial response to amyloid pathology in mice

The adenosine triphosphate-binding cassette transporter A7 (ABCA7) gene is ranked as one of the top susceptibility loci for Alzheimer's disease (AD). While ABCA7 mediates lipid transport across cellular membranes, ABCA7 loss of function has been shown to exacerbate amyloid-β (Aβ) pathology and compromise microglial function. Our family-based study uncovered an extremely rare ABCA7 p.A696S variant that was substantially segregated with the development of AD in 3 African American families. Using the knockin mouse model, we investigated the effects of ABCA7-A696S substitution on amyloid pathology and brain immune response in 5xFAD transgenic mice. Importantly, our study demonstrated that ABCA7-A696S substitution reduces amyloid plaque-associated microgliosis and increases dystrophic neurites around amyloid deposits compared to control mice. We also found increased X-34-positive amyloid plaque burden in 5xFAD mice with ABCA7-A696S substitution, while there was no evident difference in insoluble Aβ levels between mouse groups. Thus, ABCA7-A696S substitution may disrupt amyloid compaction resulting in aggravated neuritic dystrophy due to insufficient microglia barrier function. In addition, we observed that ABCA7-A696S substitution disturbs the induction of proinflammatory cytokines interleukin 1β and interferon γ in the brains of 5xFAD mice, although some disease-associated microglia gene expression, including Trem2 and Tyrobp, are upregulated. Lipidomics also detected higher total lysophosphatidylethanolamine levels in the brains of 5xFAD mice with ABCA7-A696S substitution than controls. These results suggest that ABCA7-A696S substitution might compromise the adequate innate immune response to amyloid pathology in AD by modulating brain lipid metabolism, providing novel insight into the pathogenic mechanisms mediated by ABCA7. ONE SENTENCE SUMMARY: A rare Alzheimer's disease risk ABCA7 p.A696S variant compromises microglial response to amyloid pathology.

A Peptide Motif Covering Splice Site B in Neuroligin-1 Binds to Aβ and Acts as a Neprilysin Inhibitor

The most common cause of dementia among elderly people is Alzheimer's disease (AD). The typical symptom of AD is the decline of cognitive abilities, which is caused by loss of synaptic function. Amyloid-β (Aβ) oligomers play a significant role in the development of this synaptic dysfunction. Neuroligin-(NL)1 is a postsynaptic cell-adhesion molecule located in excitatory synapses and involved in the maintenance and modulation of synaptic contacts. A recent study has found that Aβ interacts with the soluble N-terminal fragment of NL1. The present study aimed to elucidate the role of NL1 in Aβ-induced neuropathology. Employing surface plasmon resonance and competitive ELISA, we confirmed the high-affinity binding of NL1 to the Aβ peptide. We also identified a sequence motif representing the NL1-binding site for the Aβ peptide and showed that a synthetic peptide modeled after this motif, termed neurolide, binds to the Aβ peptide with high affinity, comparable to the NL1-Aβ interaction. To assess the effect of neurolide in vivo, wild-type and 5XFAD mice were subcutaneously treated with this peptide for 10 weeks. We observed an increase in Aβ plaque formation in the cortex of neurolide-treated 5XFAD mice. Furthermore, we showed that neurolide reduces the activity of neprilysin, the predominant Aβ-degrading enzyme in the brain. Accordingly, we suggest that neurolide is the NL1-binding site for Aβ peptide, and acts as an inhibitor of neprilysin activity. Based on these data, we confirm the involvement of NL1 in the development of AD and suggest a mechanism for NL1-induced Aβ plaque formation.

Multi-omics analyses of early-onset familial Alzheimer's disease and Sanfilippo syndrome zebrafish models reveal commonalities in disease mechanisms

Sanfilippo syndrome (mucopolysaccharidosis type III, MPSIII) causes childhood dementia, while Alzheimer's disease is the most common type of adult-onset dementia. There is no cure for either of these diseases, and therapeutic options are extremely limited. Increasing evidence suggests commonalities in the pathogenesis of these diseases. However, a direct molecular-level comparison of these diseases has never been performed. Here, we exploited the power of zebrafish reproduction (large families of siblings from single mating events raised together in consistent environments) to conduct sensitive, internally controlled, comparative transcriptome and proteome analyses of zebrafish models of early-onset familial Alzheimer's disease (EOfAD, psen1Q96_K97del/+) and MPSIIIB (nagluA603fs/A603fs) within single families. We examined larval zebrafish (7 days post fertilisation), representing early disease stages. We also examined the brains of 6-month-old zebrafish, which are approximately equivalent to young adults in humans. We identified substantially more differentially expressed genes and pathways in MPS III zebrafish than in EOfAD-like zebrafish. This is consistent with MPS III being a rapidly progressing and earlier onset form of dementia. Similar changes in expression were detected between the two disease models in gene sets representing extracellular matrix receptor interactions in larvae, and the ribosome and lysosome pathways in 6-month-old adult brains. Cell type-specific changes were detected in MPSIIIB brains at 6 months of age, likely reflecting significant disturbances of oligodendrocyte, neural stem cell, and inflammatory cell functions and/or numbers. Our 'omics analyses have illuminated similar disease pathways between EOfAD and MPS III indicating where efforts to find mutually effective therapeutic strategies can be targeted.

Inspecting the Triazole Scaffold as Powerful Antifibril Agents against 2N4R Tau and α-Synuclein Aggregates

Alzheimer's (AD) and Parkinson's (PD) disease are neurodegenerative disorders that are considered to be a significant global health challenge due to their increasing prevalence and profound impact on both individuals and society. These disorders are characterized by the progressive loss of neuronal function, leading to cognitive and motor impairments. A key pathological feature of AD and PD is the abnormal accumulation of misfolded proteins within the brain. In AD, amyloid-beta aggregates into plaques, while tau proteins form neurofibrillary tangles (NFTs). Parkinson's disease, on the other hand, is marked by the accumulation of α-synuclein (α-syn) in the form of Lewy bodies (LBs). These protein aggregates are involved in neuronal dysfunction and neurodegeneration, contributing to disease progression. Research efforts are increasingly focused on identifying small molecules that can simultaneously target multiple pathological processes, offering the potential to not only alleviate symptoms but also modify the progression of neurodegeneration. Herein, a novel group of triazole-based compounds was designed and synthesized to curtail the aggregation of α-syn and tau proteins, which are closely linked to the physiopathology of PD and AD, respectively. A thioflavin T (ThT) fluorescence assay was used to measure fibril formation and assess the antiaggregation effects of various compounds. To further validate these findings, transmission electron microscopy (TEM) was employed as a direct method to visualize the impact of these compounds on fibril morphology. Inhibition of oligomer formation was evaluated using photoinduced cross-linking of unmodified proteins (PICUP), enabling the detection of early protein aggregation events. During fibril formation assays, three compounds (3e, 4b, 4d) demonstrated superior inhibitory activity as assessed by ThT fluorescence and TEM imaging. Subsequent evaluations, which included tests for antioligomer, anti-inclusion, and disaggregation effects identified compound 4d as the most promising candidate overall.

Amyloid-β oligomers drive amyloid deposit and cascaded tau pathology of Alzheimer's disease in aged brains of non-human primates

Alzheimer's disease (AD), the most prevalent form of dementia, disproportionately affects the elderly population. While aging is widely recognized as a major risk factor for AD, the precise mechanisms by which aging contributes to the pathogenesis of AD remain poorly understood. In our previous work, the neuropathological changes in the brains of aged cynomolgus monkeys (≥18 years old) following parenchymal cerebral injection of amyloid-β oligomers (AβOs) have been characterized. Here, we extend our investigation to middle-aged cynomolgus monkeys (≤15 years old) to establish an AD model. Surprisingly, immunohistochemical analysis reveals no detectable AD-related pathology in the brains of middle-aged monkeys, even after AβOs injection. In a comprehensive pathological analysis of 38 monkeys, we observe that the amyloid-β (Aβ) burden increases significantly with advancing age. Notably, the density of Aβ plaques is markedly higher in the ventral regions compared to the dorsal regions of aged monkey brains. Furthermore, we demonstrate that tau phosphorylation coincides with the accumulation of extensive Aβ plaques and exhibits a positive correlation with Aβ burden in aged monkeys. Collectively, these findings underscore the critical role of the aged brain in providing the necessary conditions for AβO-induced AD pathologies in cynomolgus monkeys.

Interaction of genetic variants and methylation in transcript-level expression regulation in Alzheimer's disease by multi-omics data analysis

BACKGROUND

Alzheimer's disease (AD) presents a significant public health problem and major cause of dementia. Not only genetic but epigenetic factors contribute to complex and heterogeneous molecular mechanisms underlying AD risk; in particular, single nucleotide polymorphisms (SNPs) and DNA methylation can lead to dysregulation of gene expression in the AD brain. Each of these regulators has been independently studied well in AD progression, however, their interactive roles, particularly when they are located differently, still remains unclear. Here, we aimed to explore the interplay between SNPs and DNA methylation in regulating transcript expression levels in the AD brain through an integrative analysis of whole-genome sequencing, RNA-seq, and methylation data measured from the dorsolateral prefrontal cortex.

RESULTS

We identified 179 SNP-methylation combination pairs that showed statistically significant interactions associated with the expression of 67 transcripts (63 unique genes), enriched in functional pathways, including immune-related and post-synaptic assembly pathways. Particularly, a number of HLA family genes (HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DRB5, HLA-DPA1, HLA-K, HLA-DQB1, and HLA-DMA) were observed as having expression changes associated with the interplay.

CONCLUSIONS

Our findings especially implicate immune-related pathways as targets of these regulatory interactions. SNP-methylation interactions may thus contribute to the molecular complexity underlying immune-related pathogenies in AD patients. Our study provides a new molecular knowledge in the context of the interplay between genetic and epigenetic regulations, in that it concerns transcript expression status in AD.

Neural Mechanism of Cognitive Reserve in Acupuncture Stimulation: Protocol for a Randomized, Placebo-Controlled Functional Near-Infrared Spectroscopy Trial

BACKGROUND

Dementia is a clinical syndrome characterized by a progressive decline in various cognitive domains. Since there is still no treatment for dementia, early diagnosis and prevention are the best approaches. In this context, the cognitive reserve (CR) concept has received considerable attention in dementia research with regard to prognosis. It originates from discrepancies between the degree of brain pathology and clinical manifestations. Acupuncture, as a complementary intervention, has long been widely applied in neurological diseases in East Asia. At the macroscale level, how acupuncture stimulation affects neural activity concerning CR in normal aging and dementia is largely unknown.

OBJECTIVE

The aim of this study is to investigate the acute neural mechanisms of acupuncture stimulation concerning CR in the normal aging group and the group with cognitive impairment using neuroimaging methods.

METHODS

This study is a randomized, placebo-controlled trial. Participants without (n=30) and with cognitive impairment (n=30) will be randomly assigned to the verum or sham acupuncture groups. The verum acupuncture group will receive acupuncture stimulation at acupoints related to cognitive function and gain deqi sensation. The sham acupuncture group will receive superficial needling at nonacupoints not related to cognitive function. Each group will undergo cognitive function tests, functional near-infrared spectroscopy imaging before and after acupuncture stimulation, and an assessment of CR. The primary outcomes will be differences in resting brain activities according to disease status, differences in resting brain connectivity before and after acupuncture stimulation between the 2 groups, and changes in brain activity in relation to the CR index. The secondary outcomes will be brain connectivity or network metrics associated with CR and differences in neural activity between the cognitive task and resting states.

RESULTS

The recruitment began in August 2023; to date, there have been 50 participants, divided into 20 in the group with cognitive impairment and 30 in the unimpaired group. The recruitment process will continue until February 2025.

CONCLUSIONS

CR refers to the individual susceptibility to age-related brain changes and pathologies in cognitive impairment, and it is a factor affecting the trajectories of the disease. Although acupuncture is a widely used intervention for various neurological diseases, including dementia, its mechanism associated with CR at the macroscale has not been clearly identified. This study could contribute to identifying the neural mechanisms of acupuncture stimulation associated with CR using neuroimaging methods and provide a basis for future longitudinal research.

TRIAL REGISTRATION

Clinical Research Information Service of the Republic of Korea KCT0008719; https://tinyurl.com/ydv5537n.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/66838.

Integrative Epigenomic Landscape of Alzheimer's Disease Brains Reveals Oligodendrocyte Molecular Perturbations Associated with Tau

Alzheimer's disease (AD) brains are characterized by neuropathologic and biochemical changes that are highly variable across individuals. Capturing epigenetic factors that associate with this variability can reveal novel biological insights into AD pathophysiology. We conducted an epigenome-wide association study of DNA methylation (DNAm) in 472 AD brains with neuropathologic measures (Braak stage, Thal phase, and cerebral amyloid angiopathy score) and brain biochemical levels of five proteins (APOE, amyloid-β (Aβ)40, Aβ42, tau, and p-tau) core to AD pathogenesis. Using a novel regional methylation (rCpGm) approach, we identified 5,478 significant associations, 99.7% of which were with brain tau biochemical measures. Of the tau-associated rCpGms, 93 had concordant associations in external datasets comprising 1,337 brain samples. Integrative transcriptome-methylome analyses uncovered 535 significant gene expression associations for these 93 rCpGms. Genes with concurrent transcriptome-methylome perturbations were enriched in oligodendrocyte marker genes, including known AD risk genes such as BIN1 , myelination genes MYRF, MBP and MAG previously implicated in AD, as well as novel genes like LDB3 . We further annotated the top oligodendrocyte genes in an additional 6 brain single cell and 2 bulk transcriptome datasets from AD and two other tauopathies, Pick's disease and progressive supranuclear palsy (PSP). Our findings support consistent rCpGm and gene expression associations with these tauopathies and tau-related phenotypes in both bulk brain tissue and oligodendrocyte clusters. In summary, we uncover the integrative epigenomic landscape of AD and demonstrate tau-related oligodendrocyte gene perturbations as a common potential pathomechanism across different tauopathies.

Retinal ganglion cell vulnerability to pathogenic tau in Alzheimer's disease

Pathological tau isoforms, including hyperphosphorylated tau at serine 396 (pS396-tau) and tau oligomers (Oligo-tau), are elevated in the retinas of patients with mild cognitive impairment (MCI) due to Alzheimer's disease (AD) and AD dementia. These patients exhibit significant retinal ganglion cell (RGC) loss, however the presence of tau isoforms in RGCs and their impact on RGC integrity, particularly in early AD, have not been studied. Here, we analyzed retinal superior temporal cross-sections from 25 MCI or AD patients and 16 age- and sex-matched cognitively normal controls. Using the RGC marker ribonucleic acid binding protein with multiple splicing (RBPMS) and Nissl staining, we found a 46-56% reduction in RBPMS+ RGCs and Nissl+ neurons in the ganglion cell layer (GCL) of MCI and AD retinas (P < 0.05-0.001). RGC loss was accompanied by soma hypertrophy (10-50% enlargement, P < 0.05-0.0001), nuclear displacement, apoptosis (30-50% increase, P < 0.05-0.01), and prominent expression of granulovacuolar degeneration (GVD) bodies and GVD-necroptotic markers. Both pS396-tau and Oligo-tau were identified in RGCs, including in hypertrophic cells. PS396-tau+ and Oligo-tau+ RGC counts were significantly increased by 2.1-3.5-fold in MCI and AD retinas versus control retinas (P < 0.05-0.0001). Tauopathy-laden RGCs strongly inter-correlated (rP=0.85, P < 0.0001) and retinal tauopathy associated with RGC reduction (rP=-0.40-(-0.64), P < 0.05-0.01). Their abundance correlated with brain pathology and cognitive deficits, with higher tauopathy-laden RGCs in patients with Braak stages (V-VI), clinical dementia ratings (CDR = 3), and mini-mental state examination (MMSE ≤   26) scores. PS396-tau+ RGCs in the central and mid-periphery showed the closest associations with disease status, while Oligo-tau+ RGCs in the mid-periphery exhibited the strongest correlations with brain pathology (NFTs, Braak stages, ABC scores; rS=0.78-0.81, P < 0.001-0.0001) and cognitive decline (MMSE; rS=-0.79, P = 0.0019). Overall, these findings identify a link between pathogenic tau in RGCs and RGC degeneration in AD, involving apoptotic and GVD-necroptotic cell death pathways. Future research should validate these results in larger and more diverse cohorts and develop RGC tauopathy as a potential noninvasive biomarker for early detection and monitoring of AD progression.

Novel Soluble Epoxide Hydrolase Inhibitor: Toward Regulatory Preclinical Studies

Neuroinflammation is widely recognized as a key pathological hallmark of Alzheimer's disease (AD). Recently, inhibiting soluble epoxide hydrolase (sEH) has emerged as a promising therapeutic strategy for AD. sEH plays a pivotal role in neuroinflammation by hydrolyzing epoxyeicosatrienoic acids (EETs), which have anti-inflammatory and neuroprotective properties, into pro-inflammatory dihydroepoxyeicosatrienoic acids (DHETs). Furthermore, the overexpression of the enzyme in the brains of AD patients and animal models of the disease highlights its relevance as a therapeutic target. Our previous studies, using the inhibitor UB-SCG-51 demonstrated that sEH inhibition regulates neuroinflammation and other mechanisms, such as the unfolded protein response pathway, while reducing autophagy, apoptosis, and neuronal death, thereby promoting neuroprotection. Building on these findings, we evaluated the arginine salt of the compound, designated UB-SCG-74, which offers improved oral absorption compared to that of UB-SCG-51 while retaining high permeability, potency, and selectivity. In experiments using 5XFAD mice, UB-SCG-74 treatment significantly improved cognition and synaptic plasticity, outperforming donepezil, a standard AD drug, and ibuprofen, an anti-inflammatory drug. Remarkably, these benefits persisted for 4 weeks after administration cessation, suggesting lasting therapeutic effects. Safety pharmacology studies showed no toxicity, supporting the advancement of UB-SCG-74 into preclinical regulatory evaluation. Our findings further indicate that sEH inhibition engages multiple neuroprotective pathways, potentially modifying both AD symptoms and disease progression, thus reinforcing its therapeutic potential.

Efficacy of acetylcholinesterase inhibitors on reducing hippocampal atrophy rate: a systematic review and meta-analysis

BACKGROUND

Neurodegenerative diseases (NDs) are conditions characterized by irreversible progressive degeneration to the nervous tissue and are usually associated with cognitive decline and functional deficits, especially in elderly. Acetylcholinesterase inhibitors (AChEIs) like donepezil, rivastigmine, and galantamine are commonly prescribed to alleviate cognitive symptoms associated with NDs. However, their long-term impact on slowing structural brain degeneration, particularly hippocampal atrophy, remains unclear.

OBJECTIVE

This systematic review and meta-analysis assess the efficacy of AChEIs in reducing hippocampal atrophy in patients with NDs or clinical syndromes that lead to cognitive decline.

METHODS

A systematic search of PubMed, Scopus, Web of Science, and Cochrane databases, since inception till 20th August 2024, identified randomized controlled trials (RCTs) and comparative studies that measured hippocampal volume changes in elderly patients with NDs and other clinical syndromes. Random effect model was employed to estimate the pooled atrophy rates. Subgroup analysis was conducted by disease, dosage, and side of the measurement.

RESULTS

From 5,943 initially screened studies, nine were included in the review, and six were analyzed in the meta-analysis, encompassing a total of 2,179 participants. The meta-analysis showed that donepezil at a 10 mg dose significantly reduced hippocampal atrophy compared to placebo (SMD = 0.44, 95% CI [0.08 to 0.81], p = 0.01), whereas the 5 mg dose showed no significant effect on hippocampal volume. Overall, pooled results favored donepezil in reducing hippocampal atrophy (SMD = 0.33, p = 0.04), indicating that higher doses are more effective. Among patients with mild cognitive impairment (MCI), both donepezil and vitamin E were associated with a significant reduction in hippocampal atrophy compared to placebo (SMD = 0.27, p = 0.01). In contrast, galantamine did not significantly reduce hippocampal atrophy in the overall analysis, but it was associated with reduced whole brain atrophy in APOE ε4 carriers. Further analysis revealed no significant difference in the reduction of right or left hippocampal atrophy in donepezil-treated patients. These findings suggest that donepezil, particularly at higher doses, may have a protective effect against hippocampal atrophy in patients with AD and MCI, while galantamine's effect may be more limited, especially in certain genetic subgroups.

CONCLUSION

Higher doses of donepezil (10 mg) significantly reduce hippocampal atrophy in Alzheimer's disease and mild cognitive impairment, suggesting potential neuroprotective effects. In contrast, lower doses (5 mg) and galantamine showed no significant impact on hippocampal volume, though galantamine reduced whole brain atrophy in APOE ε4 carriers. Dosage and genetic factors are crucial in determining the efficacy of acetylcholinesterase inhibitors in slowing neurodegeneration.

The impact of apolipoprotein E, type ∊4 allele on Alzheimer's disease pathological biomarkers: a comprehensive post-mortem pilot-analysis

The apolipoprotein E type ∊4 allele (ApoE4) is known as the strongest genetic risk factor for Alzheimer's Disease (AD). Meanwhile, many aspects of its impact on AD pathology remain underexplored. This study conducts a systematic data analysisof donor data from the Seattle Alzheimer's Disease Brain Cell Atlas. Our investigation delves into the intricate interplay between identified biomarkers and their correlation with ApoE4 across all severities of AD. Employing Pearson R correlation, and one-way and two-way ANOVA tests, we elucidate the pathological changes in biomarkers and the altering effects of ApoE4. Remarkably, the phosphorylation of tau observed in neurofibrillary tangles (NFTs) marked by the AT8 antibody, emerges as the most correlated factor with other pathological biomarkers. This correlation is mediated by both tau and amyloid pathology, suggesting a higher hierarchical role in determining AD pathological effects than other biomarkers. However, non-ApoE4 carriers exhibit a more significant correlation with disease progression severity compared to ApoE4 carriers, though ApoE4 carriers demonstrate significance in exacerbating the effect of accumulating phosphorylated tau and amyloid plaques assessed by AT8 and 6E10 antibodies. Furthermore, our analysis does not observe dramatic neuronal changes in grey matter across the span of AD pathology. Glia activation, measured by Iba1 and GFAP, demonstrates an amyloid-specific correlation. This research marks the first human post-mortem analysis providing a comprehensive examination of prevailing AD biomarkers and their interconnectedness with pathology and ApoE4 genetic factor. Limitations in the study are acknowledged, underscoring the need for further exploration and refinement in future research endeavors.