Pathological mechanisms and therapeutic strategies for Alzheimer's disease

The roles of pleiotrophin in brain injuries: a narrative review of the literature

BACKGROUND

Pleiotrophin (PTN), a secreted multifunctional growth factor, is highly expressed in the developing brain. Recently, many studies have indicated that PTN participates in the development of brain and plays a neuroprotection after brain injury, especially promoting neuronal survival and neurite outgrowth, stimulating oligodendrocyte maturation and myelination, modulating neuroinflammation, and so on.

OBJECTIVE

However, no reviews comprehensively summarize the roles of PTN in brain injuries. Considering this, this review focuses on the roles and related regulatory pathways of PTN in brain injuries, what is known to date.

METHODS

PubMed and Embase databases have been searched, and related studies are compiled and summarized.

RESULTS

Our review has found PTN participates in the repairment of brain injuries, including hypoxic-ischemic brain injury, preterm white matter injury, traumatic brain injury, and neurodegenerative diseases, mainly based on animal data and small sample size studies. Besides, PTN interacts with receptors, such as, Z-type protein tyrosine phosphatase receptor and syndecan-3, regulating related pathways in these events.

CONCLUSION

It suggests PTN as a promising candidate for the treatment of brain injuries clinically. However, the evidence is early in its development. Further multi-center and large-sample studies are warranted to support our findings and determine the clinical value of PTN for treating brain injuries.

The compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one alleviates neuroinflammation and cognitive impairment in a mouse model of Alzheimer's disease

JOURNAL/nrgr/04.03/01300535-202511000-00034/figure1/v/2024-12-20T164640Z/r/image-tiff Previous studies have shown that the compound (E)-2-(3,4-dihydroxystyryl)-3-hydroxy-4H-pyran-4-one (D30), a pyromeconic acid derivative, possesses antioxidant and anti-inflammatory properties, inhibits amyloid-β aggregation, and alleviates scopolamine-induced cognitive impairment, similar to the phase III clinical drug resveratrol. In this study, we established a mouse model of Alzheimer's disease via intracerebroventricular injection of fibrillar amyloid-β to investigate the effect of D30 on fibrillar amyloid-β-induced neuropathology. Our results showed that D30 alleviated fibrillar amyloid-β-induced cognitive impairment, promoted fibrillar amyloid-β clearance from the hippocampus and cortex, suppressed oxidative stress, and inhibited activation of microglia and astrocytes. D30 also reversed the fibrillar amyloid-β-induced loss of dendritic spines and synaptic protein expression. Notably, we demonstrated that exogenous fibrillar amyloid-β introduced by intracerebroventricular injection greatly increased galectin-3 expression levels in the brain, and this increase was blocked by D30. Considering the role of D30 in clearing amyloid-β, inhibiting neuroinflammation, protecting synapses, and improving cognition, this study highlights the potential of galectin-3 as a promising treatment target for patients with Alzheimer's disease.

Exploring the nexus: Sleep disorders, circadian dysregulation, and Alzheimer's disease

We reviewed the connections among Alzheimer's disease (AD), sleep deprivation, and circadian rhythm disorders. Evidence is mounting that disrupted sleep and abnormal circadian rhythms are not merely symptoms of AD, but are also involved in accelerating the disease. Amyloid-beta (Aβ) accumulates, a feature of AD, and worsens with sleep deprivation because glymphatic withdrawal is required to clear toxic proteins from the brain. In addition, disturbances in circadian rhythm can contribute to the induction of neuroinflammation and oxidative stress, thereby accelerating neurodegenerative processes. While these interactions are bidirectional, Alzheimer's pathology further disrupts sleep and circadian function in a vicious cycle that worsens cognitive decline, which is emphasized in the review. The evidence that targeting sleep and circadian mechanisms may serve as therapeutic strategies for AD was strengthened by this study through the analysis of the molecular and physiological pathways. Further work on this nexus could help unravel the neurobiological mechanisms common to the onset of Alzheimer's and disrupted sleep and circadian regulation, which could result in earlier intervention to slow or prevent the onset of the disease.

A nasally administrated reactive oxygen species-responsive carrier-free gene delivery nanosystem for Alzheimer's disease combination therapy

Combination therapies targeting multiple pathways are needed in order to improve treatment outcomes in Alzheimer's disease (AD) due to its complex pathogenesis. Amyloid-β and microglia-mediated neuroinflammation significantly contribute to AD pathogenesis. Amyloid-β-related nucleic acid drugs have demonstrated considerable potential in AD treatment; however, their clinical translation is limited by complex synthesis processes and carrier toxicity. Herein, an intranasally administrated, reactive oxygen species (ROS)-responsive, carrier-free gene delivery nanosystem (FTBR-NAC) was constructed for re-polarizing microglia and decreasing amyloid-β expression. In this nanosystem, fingolimod was conjugated with biguanide via an ROS-responsive linker to form the carrier for β-secretase 1 siRNA (siBACE1) to form FTBR nanoparticles. The electropositivity of FTBR and mucolytic activity of N-acetylcysteine (NAC) together enhanced the brain entry of FTBR. Upon reaching the brain, FTBR responded to the elevated ROS at the pathological site, releasing siBACE1 and fingolimod. Administration of FTBR-NAC improved cognitive function in AD mice, demonstrating the high therapeutic efficacy of this relatively simple nanosystem.

Role of mitogen-activated protein kinase inhibitors in Alzheimer's disease: Rouge of brain kinases

Alzheimer's disease (AD) is the chief cause of dementia and related mortality worldwide due to progressive accumulation of amyloid peptide (Aβ) and hyperphosphorylated tau protein. These neuropathological changes lead to cognitive impairment and memory dysfunction. Notably, most Food drug Administration (FDA) approved anti-AD medications such as tacrine and donepezil are engaged with symptomatic relief of cognitive impairment but do not reverse the underlying AD neuropathology. Therefore, searching for new anti-AD is advisable. It has been shown that the inflammatory signaling pathways such as mitogen-activated protein kinases (MAPK) are intricate with the Aβ and tau protein neuropathology in AD. In addition, inhibition of brain MAPK plays a critical role in mitigating cognitive dysfunction in early-onset AD. Though, the fundamental mechanisms for the beneficial effects of MAPK inhibitors were not fully explained. Therefore, this review aims to discuss the potential molecular mechanisms of MAPK inhibitors in AD.

Triple-Target Inhibition of Cholinesterase, Amyloid Aggregation, and GSK3β to Ameliorate Cognitive Deficits and Neuropathology in the Triple-Transgenic Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) poses one of the most urgent medical challenges in the 21st century as it affects millions of people. Unfortunately, the etiopathogenesis of AD is not yet fully understood and the current pharmacotherapy options are somewhat limited. Here, we report a novel inhibitor, Compound 44, for targeting cholinesterases, amyloid-β (Aβ) aggregation, and glycogen synthase kinase 3β (GSK-3β) simultaneously with the aim of achieving symptomatic relief and disease modification in AD therapy. We found that Compound 44 had good inhibitory effects on all intended targets with IC50s of submicromolar or better, significant neuroprotective effects in cell models, and beneficial improvement of cognitive deficits in the triple transgenic AD (3 × Tg AD) mouse model. Moreover, we showed that Compound 44 acts as an autophagy regulator by inducing nuclear translocation of transcription factor EB through GSK-3β inhibition, enhancing the biogenesis of lysosomes and elevating autophagic flux, thus ameliorating the amyloid burden and tauopathy, as well as mitigating the disease phenotype. Our results suggest that triple-target inhibition via Compound 44 could be a promising strategy that may lead to the development of effective therapeutic approaches for AD.

Targeting of PP2 A/GSK3β/PTEN Axis in Alzheimer Disease: The Mooting Evidence, Divine, and Devil

Alzheimer disease (AD) is a progressive neurodegenerative disease of the brain due to extracellular accumulation of Aβ. In addition, intracellular accumulation of hyperphosphorlyated tau protein which form neurofibrillary tangle (NFT) is associated with progressive neuronal injury and the development of AD. Aβ and NFTs interact together to induce inflammation and oxidative stress which further induce neurodegeneration in AD. The exact relationship between Aβ and tau, the two proteins that accumulate within these lesions, has proven elusive. A growing body of work supports the notion that Aβ may directly or indirectly interact with tau to accelerate NFTs formation. Aβ can adversely affect distinct molecular and cellular pathways, thereby facilitating tau phosphorylation, aggregation, mislocalization, and accumulation. Aβ may drive tau pathology by activating specific kinases, providing a straightforward mechanism by which Aβ may enhance tau hyperphosphorylation and NFT formation. Many cellular signaling pathways such as protein phosphatase 2A (PP2A), glycogen synthase kinase 3β (GSK3β), and phosphatase and tensin homologue (PTEN) are intricate in AD neuropathology. PP2A which involved in the dephosphorylation of tau protein is deregulated in AD, and correlated with cognitive impairment. PTEN is a critical regulator of neuronal growth, survival, and development, improving synaptic plasticity and axonal regeneration. Nevertheless, mutated PTEN is associated with the development of cognitive impairment by inhibiting the expression and the activity of PP2A. Furthermore, dysregulation of GSK3β affects Aβ, tau protein phosphorylation, synaptic plasticity and other signaling pathways involved in the pathogenesis of AD. Therefore, there is a close interaction among GSK3β, PTEN, and PP2A. GSK3β exaggerates AD neuropathology by inhibiting PP2A and activates the expression of PTEN. These findings specified a related interaction among GSK3β, PTEN, and PP2A, and modulation of the single component of this axis may not produce an effective effect against AD neuropathology. Modulation of this axis by metformin and statins can reduce AD neuropathology. Therefore, this review aims to discuss the role of GSK3β/PTEN/PP2A axis in AD neuropathology and how targeting of this axis by metformin and statins can produce effective therapeutic strategy in the management of AD. In conclusion, inhibition of GSK3β and PTEN and activation of PP2A may be more suitable than modulation of single signaling pathway. Metformin and statins by activating PP2A and inhibiting of GSK3β and PTEN attenuate the development and progression of AD.

Integrating NLP and LLMs to discover biomarkers and mechanisms in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurological condition characterized by cognitive decline, memory loss, and aberrant behaviour. It affects millions of people globally and is one of the main causes of dementia. The neurodegenerative condition known as AD has intricate, multifaceted mechanisms that make it difficult to comprehend and identify in its early stages. Conventional diagnostic techniques frequently fail to detect the disease in its early stages. By combining Natural Language Processing (NLP) and Large Language Models (LLMs), this research suggests a novel approach for identifying potential biomarkers and underlying mechanisms of AD. Clinical data is gathered from publicly accessible databases and healthcare facilities, including genetic information, neuroimaging scans, and medical records. The pre-processing of unstructured clinical notes involves tokenization and genetic profiles and neuroimaging data are normalized by Z-score normalization for consistency. Multi-Input Convolutional Neural Networks (MI-CNN) are employed to efficiently fuse diverse data sources, allowing for a thorough analysis. Key biomarkers linked to AD are identified and categorized using the Genetic Algorithm combined with Bidirectional Encoder Representations from Transformers (BERT) (GenBERT). By fine-tuning BERT's hyperparameters using genetic optimization approaches, GenBERT enables the effective analysis of large medical datasets, such as patient histories, genetic data, and clinical notes. The combination strategy increases feature selection and the model's capacity to identify minute genomic and linguistic patterns suggestive of AD. The goal of this integrated strategy is to provide early diagnostic tools and new insights into the pathogenesis of the disease, which could transform methods for detecting and treating AD. As it concerns early AD prediction, the GenBERT model performs better than current techniques, obtaining the highest accuracy (98.30%) and F1-score (0.97), as well as greater precision (0.95) and recall (0.92). Additionally, it demonstrates its capacity to reliably identify both positive and negative AD cases with sensitivity (98.65%) and specificity (99.73%). Overall, GenBERT offers a trustworthy and useful tool for AD early diagnosis.

Albumin antagonizes Alzheimer's disease-related Tau pathology and enhances cognitive performance by inhibiting aberrant Tau aggregation

Alzheimer's disease (AD) is a neurodegenerative disorder primarily characterized by cognitive impairment, for which effective treatments remain lacking. Albumin (ALB) is an essential carrier protein found in various body fluids, playing crucial roles in anti-inflammatory processes, antioxidation, and signal transduction. Recent research indicates that ALB may play a significant role in the development and progression of AD, though its specific function is not yet fully understood. In this study, we observed a link between serum ALB levels and cognitive performance in the elderly. Administration of ALB intranasally was shown to enhance learning and memory in MAPT/P301S transgenic mice, markedly decreasing hyperphosphorylation of Tau protein and reducing neuronal apoptosis. In a neuronal cell model overexpressing Tau, ALB administration in vitro attenuated Tau-induced toxicity and reduced the production of phosphorylated Tau. Additionally, co-incubation of Tau with ALB significantly reduced the formation of neurofibrillary tangles. These results suggest that ALB improves AD-related cognitive function by preventing the pathological aggregation of Tau and reducing its abnormal phosphorylation. Furthermore, ALB's neuroprotective effect helps prevent neuronal apoptosis in the cortex and hippocampus, providing potential targets for AD prevention and treatment.

The neuroprotective role of Humanin in Alzheimer's disease: The molecular effects

Humanin (HN) is an endogenous micropeptide also known as a mitochondria-derived peptide. It has a neuroprotective effect against Alzheimer's disease (AD) and other neurodegenerative diseases by improving hippocampal acetylcholine and attenuating the development of oxidative stress and associated neurotoxicity. HN protects the neuron from the toxic effects of amyloid beta (Aβ). HN is regarded as a biomarker of mitochondrial stress. Interestingly, aging reduces brain expression of HN, leading to cognitive impairment and elevating the risk of neurodegeneration, including AD. However, in old subjects and AD patients, circulating HN levels increase as a compensatory mechanism to reduce neurodegeneration and mitochondrial dysfunction in AD. Conversely, other studies demonstrated a reduction in circulating HN levels in AD. These findings indicated controversial points regarding the precise mechanistic role of HN in AD. Therefore, the aim of this review was to discuss the exact role of HN in AD neuropathology and also to discuss the molecular mechanisms of HN in AD.

Triple-mode sensing platform for acetylcholinesterase activity monitoring and anti-Alzheimer's drug screening based on a highly stable Cu (I) compound

Acetylcholinesterase (AChE) and AChE inhibitors play critical roles in the early diagnosis and treatment of Alzheimer's disease (AD). Herein, a fluorescence/colorimetry/smartphone triple-mode sensing platform was constructed for both AChE activity monitoring and AChE inhibitor screening by exploring a Cu (I) compound, Cu3I (SR)2 (R = CH2CH2NH2), as a fluorescent probe. In comparison of most other fluorescent probes, Cu3I (SR)2 presented exceptional stability against pH, temperature, UV irradiation, redox agents, and metal ions, as well as good recyclability due to its unique chemical structure. We further found the fluorescence emission of Cu3I (SR)2 could be quenched by MnO2 nanosheet (NS) via inner filter effect, and restored by thiocholine (TCh) generated from the hydrolysis of acetylthiocholine iodide (ATCh) in the catalysis of AChE. On this basis, a fluorescence "turn-on" assay was developed for monitoring AChE activity with a detection limit of 0.03 U/L and a detection range of 0.25-50 U/L. This method demonstrates great potential for real-time detection of AChE activity in biological samples and screening of AChE inhibitors obtained from herbal extracts as anti-AD agents. Additionally, Cu3I (SR)2/MnO2 NS sensing system also exhibited a color change from brown to colorless as the increasing AChE activity, which allowed the colorimetric and smartphone detection of AChE activity.

Nanoarchitecture of CaV2.1 channels and GABAB receptors in the mouse hippocampus: Impact of APP/PS1 pathology

Voltage-gated CaV2.1 (P/Q-type) Ca2+ channels play a crucial role in regulating neurotransmitter release, thus contributing to synaptic plasticity and to processes such as learning and memory. Despite their recognized importance in neural function, there is limited information on their potential involvement in neurodegenerative conditions such as Alzheimer's disease (AD). Here, we aimed to explore the impact of AD pathology on the density and nanoscale compartmentalization of CaV2.1 channels in the hippocampus in association with GABAB receptors. Histoblotting experiments showed that the density of CaV2.1 channel was significantly reduced in the hippocampus of APP/PS1 mice in a laminar-dependent manner. CaV2.1 channel was enriched in the active zone of the axon terminals and was present at a very low density over the surface of dendritic tree of the CA1 pyramidal cells, as shown by quantitative SDS-digested freeze-fracture replica labelling (SDS-FRL). In APP/PS1 mice, the density of CaV2.1 channel in the active zone was significantly reduced in the strata radiatum and lacunosum-moleculare, while it remained unaltered in the stratum oriens. The decline in Cav2.1 channel density was found to be associated with a corresponding impairment in the GABAergic synaptic function, as evidenced by electrophysiological experiments carried out in the hippocampus of APP/PS1 mice. Remarkably, double SDS-FRL showed a co-clustering of CaV2.1 channel and GABAB1 receptor in nanodomains (~40-50 nm) in wild type mice, while in APP/PS1 mice this nanoarchitecture was absent. Together, these findings suggest that the AD pathology-induced reduction in CaV2.1 channel density and CaV2.1-GABAB1 de-clustering may play a role in the synaptic transmission alterations shown in the AD hippocampus. Therefore, uncovering these layer-dependent changes in P/Q calcium currents associated with AD pathology can benefit the development of future strategies for AD management.

Comparative Analysis of Egg Yolk Phospholipid Unsaturation and Its Impact on Neural Health in Alzheimer Disease Mice

The mechanism of egg yolk phosphatidylcholine (PC) in alleviating Alzheimer's disease (AD) has not yet been clear. The fatty acid composition of PC, especially the ratio of polyunsaturated fatty acids (PUFA), may be a critical determinant of their structural and functional roles. This study aimed to conduct a comparative analysis of the unsaturation levels of egg yolk PC and their impact on neurological health in a murine model of AD. The results showed that oral administration of high and low unsaturation PC (HUP, LUP) enhanced learning and memory abilities in AD mice, with the HUP intervention demonstrating superior efficacy compared to the LUP. Follow-up biochemical analysis of the brain tissue also suggested that HUP intervention effectively mitigated oxidative-stress damage and inhibited tau hyperphosphorylation in AD mice. Meanwhile, lipidomic analyses of the mouse hippocampus revealed that HUP intervention substantially increased the levels of phospholipids, such as PEt (phosphatidylethanol) and BisMePA (bis(methylthio)phenylacetic acid), which are recognized as vital components of neuronal cell membranes. Furthermore, HUP intervention markedly elevated the levels of phospholipids incorporating PUFAs in the hippocampus. These results revealed a mitigating role for unsaturated egg yolk PC in AD prevention and offer new insights into AD prevention from a lipidomic perspective.

Unlocking the Therapeutic Potential of Natural Products for Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative condition marked by memory loss and cognitive decline. With current treatments offering limited effectiveness, researchers are turning to natural products that can target various aspects of AD pathology. Clinically approved natural products, such as galantamine and huperzine A, have shown success in AD treatments. Furthermore, compounds such as epigallocatechin gallate, quercetin, and resveratrol are in clinical trials. This Perspective examines nearly 100 natural compounds with promising neuroprotective effects in preclinical and clinical studies. These compounds exhibit diverse pharmacological actions that help to prevent neurodegeneration while improving cognitive functions. Their unique structures further enhance their biological activities, making them promising candidates for drug discovery. This Perspective stresses the importance of further clinical research to maximize the medical benefits of these compounds and highlights their potential as innovative remedies for AD. Continued exploration of these compounds is crucial to fully leverage their capabilities in combating AD.

Therapeutic Role of Heterocyclic Compounds in Neurodegenerative Diseases: Insights from Alzheimer's and Parkinson's Diseases

Alzheimer's and Parkinson's are the most common neurodegenerative diseases (NDDs). The development of aberrant protein aggregates and the progressive and permanent loss of neurons are the major characteristic features of these disorders. Although the precise mechanisms causing Alzheimer's disease (AD) and Parkinson's disease (PD) are still unknown, there is a wealth of evidence suggesting that misfolded proteins, accumulation of misfolded proteins, dysfunction of neuroreceptors and mitochondria, dysregulation of enzymes, and the release of neurotransmitters significantly influence the pathophysiology of these diseases. There is no effective protective medicine or therapy available even with the availability of numerous medications. There is an urgent need to create new and powerful bioactive compounds since the number of people with NDDs is rising globally. Heterocyclic compounds have consistently played a pivotal role in drug discovery due to their exceptional pharmaceutical properties. Many clinically approved drugs, such as galantamine hydrobromide, donepezil hydrochloride, memantine hydrochloride, and opicapone, feature heterocyclic cores. As these heterocyclic compounds have exceptional therapeutic potential, heterocycles are an intriguing research topic for the development of new effective therapeutic drugs for PD and AD. This review aims to provide current insights into the development and potential use of heterocyclic compounds targeting diverse therapeutic targets to manage and potentially treat patients with AD and PD.

Postbiotics as a therapeutic tool in Alzheimer's disease: Insights into molecular pathways and neuroprotective effects

Alzheimer's disease (AD) is a progressive neurodegenerative disease, characterized by oxidative stress, neuroinflammation, mitochondrial dysfunction, neurotransmitter imbalance, tau hyperphosphorylation, and amyloid beta (Aβ) accumulation in brain regions. The gut microbiota (GM) has a major impact on brain function due to its bidirectional interaction with the gut through the gut-brain axis. The gut dysbiosis has been associated with neurological disorders, emphasizing the importance of gut homeostasis in maintaining appropriate brain function. The changes in the composition of microbiomes influence neuroinflammation and Aβ accumulation by releasing pro-inflammatory cytokines, decreasing gut and blood-brain barrier (BBB) integrity, and microglial activation in the brain. Postbiotics, are bioactive compounds produced after fermentation, have been shown to provide several health benefits, particularly in terms of neuroinflammation and cognitive alterations associated with AD. Several research studies on animal models and human have successfully proven the effects of postbiotics on enhancing cognition and memory in experimental animals. This article explores the protective effects of postbiotics on cellular mechanisms responsible for AD pathogenesis and studies highlighting the influence of postbiotics as a total combination and specific compounds, including short-chain fatty acids (SCFAs). In addition, postbiotics act as a promising option for future research to deal with AD's progressive nature and improve an individual's life quality using microbiota modulation.

Long Non-Coding RNAs: Crucial Regulators in Alzheimer's Disease Pathogenesis and Prospects for Precision Medicine

Long non-coding RNAs (LncRNAs) have emerged as pivotal regulators in the pathogenesis of Alzheimer's disease (AD), a progressive neurodegenerative disorder characterized by cognitive decline and memory loss. With the capacity to modulate gene expression at various levels, LncRNAs are implicated in multiple pathological mechanisms of AD, including amyloid-beta (Aβ) accumulation, tau protein phosphorylation, neuroinflammation, and neuronal apoptosis. Recent studies have highlighted the potential of LncRNAs as diagnostic biomarkers and therapeutic targets due to their differential expression patterns in AD patients. This review synthesizes current knowledge on the role of LncRNAs in AD, focusing on their involvement in key molecular pathways and their promise as indicators for early diagnosis and prognosis. We discuss the regulatory networks of LncRNAs in the context of AD, their interaction with miRNAs, and the implications for developing novel therapeutic strategies. Despite the complexity and variability in LncRNA function, the prospect of harnessing these molecules for precision medicine in AD is gaining momentum. The translational potential of LncRNA-based interventions offers a new frontier in the quest for effective treatments and a deeper understanding of the molecular underpinnings of AD.

Lysosome-Targeting Protein Degradation Through Endocytosis Pathway Triggered by Polyvalent Nano-Chimera for AD Therapy

The excessive up-regulation of receptor for advanced glycation end products (RAGE), a well-known pathological marker, drives the onset and progression of Alzheimer's disease. Although lysosome-targeting protein degradation has emerged as an effective therapeutic modality, the limited lysosome-sorting efficacy greatly hindered the degradation efficiency of target proteins. Herein, a lysosome-shuttle-like nano-chimera (endoTAC) is proposed based on polyvalent receptor binding mode for enhanced RAGE degradation as well as precise drug delivery. The endoTAC shows a high affinity to RAGE and enhances RAGE degradation due to its polyvalent-interaction with RAGE. Additionally, endoTAC features increased accumulation in diseased brain and shows promise as a precise brain delivery system. After loading with simvastatin, the SV@endoTAC proves to successfully reverse pathological features both in vitro and in vivo. The work proposes that the combination of a lysosome-targeting chimera and an effective drug delivery system can be promising in Alzheimer's disease therapy.

Globular-shaped Aβ oligomers have diverse mechanisms for promoting Aβ aggregations with the facilitation of fibril elongation

The accumulation of amyloid β-proteins (Aβ) in the extracellular space, forming insoluble plaques, is a primary pathological process underlying Alzheimer's disease (AD). Among the various Aβ species that appear during Aβ aggregation, Aβ oligomers are considered the most neurotoxic form. However, the precise mechanisms of their molecular functions within the Aβ aggregation cascade have not been clarified so far. This research aimed to uncover the structural and functional characteristics of globular-shaped Aβ oligomers (gAβO) under in vitro conditions. We performed thioflavin T (ThT) assays on low-molecular-weight (LMW) Aβ42, testing different concentrations of Aβ42 mature fibril (MF) seeds and gAβO. Fibril formation was continuously observed using high-speed atomic force microscopy (HS-AFM) in LMW Aβ42 with different sample conditions. Conformational changes of Aβ42 aggregates in the presence of gAβO was also evaluated using circular dichroism spectroscopy. The results of the ThT analysis and HS-AFM observation indicated that gAβO promoted fibril formation of LMW Aβ42 while gAβO itself did not form fibrous aggregates, indicating that gAβO would have a catalytic effects on LMW Aβ42 aggregation. We also showed that the molecular interaction of gAβO was altered by the presence and amount of MF seeds in the reaction buffers, indicating that complex interactions would exist among different Aβ species. The results of our present research demonstrated that gAβO would have significant roles to accelerate Aβ aggregation in AD pathogenesis. 225 < 250 words.

Small extracellular vesicles derived from human induced pluripotent stem cell-differentiated neural progenitor cells mitigate retinal ganglion cell degeneration in a mouse model of optic nerve injury

JOURNAL/nrgr/04.03/01300535-202502000-00034/figure1/v/2024-05-28T214302Z/r/image-tiff Several studies have found that transplantation of neural progenitor cells (NPCs) promotes the survival of injured neurons. However, a poor integration rate and high risk of tumorigenicity after cell transplantation limits their clinical application. Small extracellular vesicles (sEVs) contain bioactive molecules for neuronal protection and regeneration. Previous studies have shown that stem/progenitor cell-derived sEVs can promote neuronal survival and recovery of neurological function in neurodegenerative eye diseases and other eye diseases. In this study, we intravitreally transplanted sEVs derived from human induced pluripotent stem cells (hiPSCs) and hiPSCs-differentiated NPCs (hiPSC-NPC) in a mouse model of optic nerve crush. Our results show that these intravitreally injected sEVs were ingested by retinal cells, especially those localized in the ganglion cell layer. Treatment with hiPSC-NPC-derived sEVs mitigated optic nerve crush-induced retinal ganglion cell degeneration, and regulated the retinal microenvironment by inhibiting excessive activation of microglia. Component analysis further revealed that hiPSC-NPC derived sEVs transported neuroprotective and anti-inflammatory miRNA cargos to target cells, which had protective effects on RGCs after optic nerve injury. These findings suggest that sEVs derived from hiPSC-NPC are a promising cell-free therapeutic strategy for optic neuropathy.

MRI Radiomics Nomogram for Predicting Disease Transition Time and Risk Stratification in Preclinical Alzheimer's Disease

RATIONALE AND OBJECTIVES

Accurate prediction of the progression of preclinical Alzheimer's disease (AD) is crucial for improving clinical management and disease prognosis. The objective of this study was to develop and validate clinical-radimoics integrated model to predict the time to progression (TTP) and disease risk stratification of preclinical AD.

MATERIALS AND METHODS

A total of 244 cases (mean age: 73.8 ± 5.5 years, 120 women) from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database were randomly divided into the training cohort (n = 172) and validation cohort (n = 72) using a 7:3 ratio. Clinical factors were identified by univariate and multivariate COX regression. Radiomics features were extracted from GM, WM and CSF of T1WI images and selected by Spearman correlation analysis and least absolute shrinkage and selection operator (LASSO). Using selected clinical factors and radiomics features, the clinical, radimocis and clinical-radiomics nomogram models were developed for predicting the TTP. The performance of each model was assessed by C-index. The risk stratification ability and predicting efficacy of the clinical-radiomics model were utilizing the Kaplan-Meier curve and receiver operator characteristic (ROC) curve.

RESULTS

The C-index of clinical, radimocis and clinical-radiomics models were 0.852 (95% confidence interval[CI]:0.810-0.893), 0.863 (95%CI:0.816-0.910) and 0.903 (95%:0.870-0.936) in the training cohort and 0.725 (95%CI:0.630-0.820), 0.788 (95%CI:0.678-0.898), 0.813(95%CI:0.734-0.892) in the validation cohort. The AUCs of the multi-predictor nomogram at 1-, 3-, 5- and 7-year were 0.894, 0.908, 0.930, 0.979 in the training cohort and 0.671, 0.726, 0.839, 0.931 in the validation cohort.

CONCLUSION

In this study, we constructed a clinical-radimoics integrated model to predict the progression of preclinical AD and stratified the risk of disease progression in preclinical AD.

GC/MS and LC-ESI-MS Analysis of Conocarpus erectus Leaves Extract via Regulating Amyloid-β-Peptide, Tau Protein, Neurotransmitters, Inflammation and Oxidative Stress against AlCl3-Induced Alzheimer's Disease in Rats

This study investigated the therapeutic effect of Conocarpus erectus leaves methanolic extract against AlCl3 -induced Alzheimer's disease (AD) in rats comparing with Donepezil-hydrochloride as a reference drug. The bioactive compounds of C. erectus leaves were isolated and identified by GC/MS and LC-ESI-MS analysis. Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), amyloid-β-peptide (Aβ-peptide), tau protein, acetylcholinesterase (AChE), serotonin (5-HT), dopamine (DA) and nor-adrenaline (NE) levels were estimated. The neuromuscular strength, memory behavior and histopathological examination of cerebral cortex region were also conducted. Forty-three compounds were characterized from the non-polar fraction of C. erectus L. leaves extract and nineteen compounds were identified from the defatted extract. AlCl3- induction caused significant elevation of brain oxidative stress, Aβ-peptide, tau protein, IL-6, TNF-α and AChE levels. A significant decrease in 5-HT, ND and DA levels were noticed. Additionally, AlCl3 reduced neuromuscular strength and compromised memory function. Treatment of AlCl3- induced rats with C. erectuse extract ameliorated these selected parameters by variable degrees. In conclusion, C. erectus protects against AlCl3- induced AD in rats through its antioxidant, anti-inflammatory, and antineural damage. [Correction added on 3 December 2024, after first online publication: The term "antineutron" was corrected to "antineural" in the preceding sentence.]. It could be considered as a new nutraceutical agent for attenuating symptoms associated with Alzheimer's disease.

Pharmacophore-based virtual screening of the chromone derivatives as potential therapeutic for Alzheimer's disease

Alzheimer's disease is one of the most complex neurological disorders and millions of people are suffering from this disease all over the world. In the past two decades acetylcholinesterase (AChE) has been the most explored pathological hallmark. The generation of potent AChE inhibitors has grown as a rapid pathological tool for the efficacious treatment of the disease. Hence, AChE enzyme is extensively explored as a drug discovery tool for the development of potent therapeutics. We have used chromone derivatives with known biological activities for developing a Gaussian field-based 3D QSAR pharmacophore model using PHASE module of Schrodinger with statistically significant R2 and Q2 values of 0.92 and 0.9209, respectively. ChEMBL and MCULE databases were screened using the best pharmacophore hypothesis model (AAHHRR_4) with features of two hydrogen bond acceptors (A1, A2), two hydrophobic regions (H1, H2), and two aromatic regions (R1, R2). These were subjected to structure-based virtual screening using extra precision, MM/GBSA and ADME calculations for calculating the binding free energies and pharmacokinetic properties, respectively. Subsequently, two hit molecules i.e. CHEMBL1319989 and MCULE-2246633290 were identified. The leads exhibited higher docking score (-8.859 and -9.984 kcal/mol) and ΔGbinding (-57.63 and -56.45 kcal/mol) as compared to the reference (ΔGbinding= -53.79 kcal/mol). MD simulation study exhibited stable interactions with the binding free energy (ΔGMMPBSA) of -27.29 and -21.26 kcal/mol for CHEMBL1319989 and MCULE-2246633290, respectively. So, the generated pharmacophore model may be considered as a valuable tool for the development of potent AChE inhibitors for the treatment of AD.

Current Status of Plant-Based Bioactive Compounds as Therapeutics in Alzheimer's Diseases

Alzheimer's disease (AD) is a common central neurodegenerative disease disorder characterized primarily by cognitive impairment and non-cognitive neuropsychiatric symptoms that significantly impact patients' daily lives and behavioral functioning. The pathogenesis of AD remains unclear and current Western medicines treatment are purely symptomatic, with a singular pathway, limited efficacy, and substantial toxicity and side effects. In recent years, as research into AD has deepened, there has been a gradual increase in the exploration and application of medicinal plants for the treatment of AD. Numerous studies have shown that medicinal plants and their active ingredients can potentially mitigate AD by regulating various molecular mechanisms, including the production and aggregation of pathological proteins, oxidative stress, neuroinflammation, apoptosis, mitochondrial dysfunction, neurogenesis, neurotransmission, and the brain-gut microbiota axis. In this review, we analyzed the pathogenesis of AD and comprehensively summarized recent advancements in research on medicinal plants for the treatment of AD, along with their underlying mechanisms and clinical evidence. Ultimately, we aimed to provide a reference for further investigation into the specific mechanisms through which medicinal plants prevent and treat AD, as well as for the identification of efficacious active ingredients derived from medicinal plants.

Resilience mechanisms underlying Alzheimer's disease

Alzheimer's disease (AD) consists of two main pathologies, which are the deposition of amyloid plaque as well as tau protein aggregation. Evidence suggests that not everyone who carries the AD-causing genes displays AD-related symptoms; they might never acquire AD as well. These individuals are referred to as non-demented individuals with AD neuropathology (NDAN). Despite the presence of extensive AD pathology in their brain, it was found that NDAN had better cognitive function than was expected, suggesting that they were more resilient (better at coping) to AD due to differences in their brains compared to other demented or cognitively impaired patients. Thus, identification of the mechanisms underlying resilience is crucial since it represents a promising therapeutic strategy for AD. In this review, we will explore the molecular mechanisms underpinning the role of genetic and molecular resilience factors in improving resilience to AD. These include protective genes and proteins such as APOE2, BDNF, RAB10, actin network proteins, scaffolding proteins, and the basal forebrain cholinergic system. A thorough understanding of these resilience mechanisms is crucial for not just comprehending the development of AD but may also open new treatment possibilities for AD by enhancing the neuroprotective pathway and targeting the pathogenic process.

Water-Soluble Ginseng Oligosaccharides Prevent Scopolamine-Induced Cholinergic Dysfunction and Inflammatory Cytokine Overexpression

Cholinergic deficiency and neuroinflammation are the two main factors of Alzheimer's disease. Recent studies have shown that water-soluble ginseng oligosaccharides (WGOS) derived from Panax ginseng roots can protect against scopolamine-induced impairments in learning and memory. However, the fundamental mechanisms remain unclear for the most part. The purpose of this study was to examine the effect of WGOS on cholinergic function and protein levels of proinflammatory cytokines in the hippocampus of mice. Mice were first pretreated with WGOS or saline, and then treated with scopolamine to establish an Alzheimer's disease model. The cognition memory of the mice was assessed through the behavioral test. The effect of WGOS on the cholinergic system was evaluated by measuring acetylcholine (ACh) neurotransmitter concentration and acetylcholinesterase (AChE) activity in the hippocampus. Using ELISA, the inflammatory cytokines IL-1β and TNF-α in the hippocampus were identified. This study found that WGOS treatment prevented the scopolamine-induced impairment of mice's recognition memory, as seen by their enhanced object recognition. In addition, WGOS prevented the scopolamine-induced decrease in ACh concentration and increase in AChE activity. Moreover, WGOS treatment inhibited scopolamine-induced upregulation of the inflammatory proteins IL-1β and TNF-α. These findings suggest that the amelioration of scopolamine-induced cognitive impairment in mice by WGOS was a consequence of the control of cholinergic function and inflammatory response in the hippocampus. Our findings suggest that WGOS should be investigated as a dietary supplement or medication for the treatment of learning and memory disorders in humans.

Data Mining Approach to Melatonin Treatment in Alzheimer's Disease: New Gene Targets MMP2 and NR3C1

Melatonin is a hormone released by the pineal gland that regulates the sleep-wake cycle. It has been widely studied for its therapeutic effects on Alzheimer's disease (AD), particularly through the amyloidosis, oxidative stress, and neuroinflammation pathways. Nevertheless, the mechanisms through which it exerts its neuroprotective effects in AD are still largely unknown. Data mining was used to identify potential gene targets that link melatonin's effects to AD pathways, yielding a comprehensive view of the underlying molecular mechanisms. We identified 3397 genes related to AD from DisGeNet and 329 melatonin gene targets from ChEMBL, which revealed 223 overlapping genes and the potential shared pathways. These genes were used to construct a protein-protein interaction (PPI) network comprising 143 nodes and 823 edges, which demonstrated significant PPI enrichment. A cluster analysis highlighted two key clusters centered on MMP2 and NR3C1, with both genes playing crucial roles in steroid hormone signaling, apoptosis, and monoamine neurotransmission. Gene Ontology (GO) enrichment and KEGG pathway analyses further elucidated their involvement in critical pathways, for instance, steroid hormone signaling and apoptosis regulation, significantly influencing AD pathology through mechanisms such as extracellular matrix remodeling, epigenetic modifications, and neuroinflammation. Our findings emphasize MMP2 and NR3C1 as important gene targets for future research on melatonin treatment in AD, paving the way for further investigations into their roles in AD pathophysiology.

The Neuroprotective Effect of Rooibos Herbal Tea Against Alzheimer's Disease: A Review

The world is experiencing a demographic shift toward an increasing proportion of elderly persons. Alzheimer's disease (AD) and other neurological disorders are far more likely to develop as people age. AD is a gradual, irreversible, and degenerative brain disorder that progressively deteriorates memory and cognitive function, eventually leading to death. Treatment for AD is the most significant unmet clinical need in neurology. There are no effective treatment options to prevent or reverse the degenerative process. The current medical management focuses primarily on temporarily easing symptoms, with little or no overall improvement. Although genetic predisposition and lifestyle factors influence the risk of neurodegenerative disorders, recent research suggests that dietary polyphenols with solid antioxidant capacities play crucial roles in determining brain health and aging. Aspalathus linearis is used to produce Rooibos, a popular South African herbal tea, which may modulate neurodegenerative mechanisms such as oxidative stress, tau protein, amyloid plaques, inflammation, and metals, all of which have been associated with AD. We reviewed the literature to evaluate the potential neuroprotective effects of Rooibos and its major flavonoids and to understand the underlying molecular mechanisms.

Ultraflexible Neural Electrodes Enabled Synchronized Long-Term Dopamine Detection and Wideband Chronic Recording Deep in Brain

Ultraflexible neural electrodes have shown superior stability compared with rigid electrodes in long-term in vivo recordings, owing to their low mechanical mismatch with brain tissue. It is desirable to detect neurotransmitters as well as electrophysiological signals for months in brain science. This work proposes a stable electronic interface that can simultaneously detect neural electrical activity and dopamine concentration deep in the brain. This ultraflexible electrode is modified by a nanocomposite of reduced graphene oxide (rGO) and poly(3,4-ethylenedioxythiophene):poly(sodium 4-styrenesulfonate) (rGO/PEDOT:PSS), enhancing the electrical stability of the coating and increasing its specific surface area, thereby improving the sensitivity to dopamine response with 15 pA/μM. This electrode can detect dopamine fluctuations and can conduct long-term, stable recordings of local field potentials (LFPs), spiking activities, and amplitudes with high spatial and temporal resolution across multiple regions, especially in deep brain areas. The electrodes were implanted into the brains of rodent models to monitor the changes in neural and electrochemical signals across different brain regions during the administration of nomifensine. Ten minutes after drug injection, enhanced neuronal firing activity and increased LFP power were detected in the motor cortex and deeper cortical layers, accompanied by a gradual rise in dopamine levels with 192 ± 29 nM. The in vivo recording consistently demonstrates chronic high-quality neural signal monitoring with electrochemical signal stability for up to 6 weeks. These findings highlight the high quality and stability of our electrophysiological/electrochemical codetection neural electrodes, underscoring their tremendous potential for applications in neuroscience research and brain-machine interfaces.

Integrated application of target-based and ligand-based drug-designing approaches for the identification of novel caspase-6 inhibitors

Caspase-6 (CASP6) is an effector caspase that has been marked to possess various pathological attributes associated with neurodegeneration. It is widely expressed in the neurodegenerative brain and peripheral tissues. It plays a vital role in apoptotic cell death and also performs non-apoptotic functions like axon pruning which contribute to the degeneration of neurons. Increment in active CASP6 levels in the cerebrospinal fluid has been observed during inflammation and has been linked to the early onset of Alzheimer's disease (AD). In the current study, a novel CASP6 inhibitor was identified with the help of integrated target-based and ligand-based drug-designing approaches. Various molecular features of US9 (PDB ID 8EG6) were used to generate models. The pharmacophore models were evaluated using the EF value, GH score, and percentage yield to select the best-suited model. The best model was used to screen the ZINC-15 database to obtain virtual hits. The undesirable compounds were eliminated using various nodes in KNIME workflow. The resulting compounds were further subjected to docking-based virtual screening (DBVS) to find the lead compounds. Further, the molecular docking studies were carried out in three stages, followed by pharmacokinetic property prediction and toxicity studies. The top two virtual hits, i.e. ZINC000012563650 and ZINC000069415222, were considered for molecular dynamics simulation studies. Compound ZINC000069415222 was found to possess better stability, drug-like properties, and lower toxicity under simulated conditions. Thus, ZINC000069415222 was identified as a potential CASP6 inhibitor that could be further explored experimentally as an anti-AD drug.

Neuroprotective properties of a thiazolidine-2,4-dione derivative as an inhibitory agent against memory impairment and phosphorylated tau: In vitro and in vivo investigations

Alzheimer's disease (AD) is the most common form of neurodegeneration that results in memory disorders and cognitive impairment. The present study investigated the neuroprotective effects of the synthesized thiazolidine-2,4-dione derivative, (E)-5-(4-chlorobenzylidene)-3-(2-oxo-2-phenylethyl)thiazolidine-2,4-dione (TZ4C), an inhibitor of p-Tau and memory impairment, using a SH-SY5Y cell model of methamphetamine-induced tauopathy and a scopolamine-induced memory impairment model in Wistar rats. In the present study, the neuroprotective effect of TZ4C was studied in a SH-SY5Y cellular model of methamphetamine-induced (2 mM) tauopathy and a scopolamine-induced (1.5 mg/kg/day) memory impairment model in male Wistar rats (n = 48). The memory functions and learning abilities of the rats were evaluated using the Morris water maze (MWM) and passive avoidance tests. Additionally, AChE activity in the rat hippocampus was quantified, and the expression of p-Tau, HSP70, and caspase-3 in both in vitro and in vivo samples was evaluated through Western blot analysis. TZ4C (0.1-1000 µM) did not exhibit significantly toxic effects on SH-SY5Y cell viability. Western blot results indicated that TZ4C led to reduced expression of p-Tau, HSP70, and cleaved caspase-3 in SH-SY5Y cells (3 and 10 µM) and the rat hippocampus (2 and 4 mg/kg). Additionally, the findings suggested that TZ4C enhanced memory function in rats with scopolamine-induced impairment and decreased acetylcholinesterase (AChE) specific activity. The comprehensive analysis of in vitro and in vivo experiments underscores the neuroprotective potential (improved neuropathology and reduced memory impairment) of TZ4C. These findings highlight the promise of TZ4C as a candidate for drug discovery programs to identify effective therapies for AD.

Modifications in the C-terminal tail of TrkC significantly alter neurotrophin-3-promoted outgrowth of neurite-like processes from PC12 cells

TrkB and TrkC are quite common neurotrophin receptors found on the same cells in CNS. In the C-terminal tail, TrkB and TrkC differ only in two amino acid residues at positions immediately preceding the tyrosine residue, which, upon phosphorylation, becomes the docking site for phospholipase Cγ1 (PLCγ1). The question arose whether such a difference near the PLCγ1 docking site might contribute to differential response to neurotrophin. PC12 clones with the following receptors were obtained: wild-type TrkC, TrkC-Y820F with a defective PLCγ1 binding site, TrkC-T817S-I819V with two amino acid residues replaced with those in the TrkB tail. The outgrowth of neurite-like processes from TrkC-Y820F-containing cells appeared to be impaired, while the TrkC-T817S-I819V variant appeared more effective than wild-type TrkC in promoting the outgrowth of neurite-like processes after neurotrophin stimulation, at least in the compared PC12 cell clones. Taken together, both the tyrosine residue at the PLCγ1 docking site and the amino acid residues immediately preceding it appear important for TrkC-supported outgrowth of neurite-like processes.

Photobiomodulation in the aging brain: a systematic review from animal models to humans

Aging is a multifactorial biological process that may be associated with cognitive decline. Photobiomodulation (PBM) is a non-pharmacological therapy that shows promising results in the treatment or prevention of age-related cognitive impairments. The aim of this review is to compile the preclinical and clinical evidence of the effect of PBM during aging in healthy and pathological conditions, including behavioral analysis and neuropsychological assessment, as well as brain-related modifications. 37 studies were identified by searching in PubMed, Scopus, and PsycInfo databases. Most studies use wavelengths of 800, 810, or 1064 nm but intensity and days of application were highly variable. In animal studies, it has been shown improvements in spatial memory, episodic-like memory, social memory, while different results have been found in recognition memory. Locomotor activity improved in Parkinson disease models. In healthy aged humans, it has been outlined improvements in working memory, cognitive inhibition, and lexical/semantic access, while general cognition was mainly enhanced on Alzheimer disease or mild cognitive impairment. Anxiety assessment is scarce and shows mixed results. As for brain activity, results outline promising effects of PBM in reversing metabolic alterations and enhancing mitochondrial function, as evidenced by restored CCO activity and ATP levels. Additionally, PBM demonstrated neuroprotective, anti-inflammatory, immunomodulatory and hemodynamic effects. The findings suggest that PBM holds promise as a non-invasive intervention for enhancing cognitive function, and in the modulation of brain functional reorganization. It is necessary to develop standardized protocols for the correct, beneficial, and homogeneous use of PBM.

Identification of novel potential cathepsin-B inhibitors through pharmacophore-based virtual screening, molecular docking, and dynamics simulation studies for the treatment of Alzheimer's disease

Cathepsin B is a cysteine protease lysosomal enzyme involved in several physiological functions. Overexpression of the enzyme enhances its proteolytic activity and causes the breakdown of amyloid precursor protein (APP) into neurotoxic amyloid β (Aβ), a characteristic hallmark of Alzheimer's disease (AD). Therefore, inhibition of the enzyme is a crucial therapeutic aspect for treating the disease. Combined structure and ligand-based drug design strategies were employed in the current study to identify the novel potential cathepsin B inhibitors. Five different pharmacophore models were developed and used for the screening of the ZINC-15 database. The obtained hits were analyzed for the presence of duplicates, interfering PAINS moieties, and structural similarities based on Tanimoto's coefficient. The molecular docking study was performed to screen hits with better target binding affinity. The top seven hits were selected and were further evaluated based on their predicted ADME properties. The resulting best hits, ZINC827855702, ZINC123282431, and ZINC95386847, were finally subjected to molecular dynamics simulation studies to determine the stability of the protein-ligand complex during the run. ZINC123282431 was obtained as the virtual lead compound for cathepsin B inhibition and may be a promising novel anti-Alzheimer agent.

Cardiovascular risk and obesity impact loss of grey matter volume earlier in males than females

BACKGROUND

It remains imperative to discover the time course that cardiovascular risk factors influence neurodegeneration in males and females and decipher whether the apolipoprotein (APOE) genotype mediates this relationship. Here we perform a large-scale evaluation of the influence of cardiovascular risk and obesity on brain volume in males and females in different age groups.

METHODS

34 425 participants between the ages of 45 and 82 years were recruited from the UK Biobank database https://www.ukbiobank.ac.uk. T1-weighted structural MR images (n=34 425) were downloaded locally for all participants, and voxel-based morphometry was performed to characterise the volumetric changes of the whole brain. The influence of Framingham cardiovascular risk (general cardiovascular risk), abdominal subcutaneous adipose tissue, and visceral adipose tissue volume (obesity) on cortical grey matter volume across different decades of life was evaluated with voxel-wise analysis.

RESULTS

In males, cardiovascular risk and obesity demonstrated the greatest influence on lower grey matter volume between 55-64 years of age. Female participants showed the greatest effect on lower grey matter volume between 65-74 years of age. Associations remained significant in APOE ε4 carriers and APOE ε4 non-carriers when evaluated separately.

CONCLUSIONS

The strongest influence of cardiovascular risk and obesity on reduced brain volume was between 55-64 years of age in males, whereas women were most susceptible to the detrimental effects of cardiovascular risk a decade later between 65-74 years of age. Here we elucidate the timing that targeting cardiovascular risk factors and obesity should be implemented in males and females to prevent neurodegeneration and Alzheimer's disease development.

Mechanism of Metal Complexes in Alzheimer's Disease

Alzheimer's disease (AD) is a kind of neurodegenerative diseases characterized by beta-amyloid deposition and neurofibrillary tangles and is also the main cause of dementia. According to statistics, the incidence of AD is constantly increasing, bringing a great burden to individuals and society. Nonetheless, there is no cure for AD, and the available drugs are very limited apart from cholinesterase inhibitors and N-Methyl-D-aspartic acid (NMDA) antagonists, which merely alleviate symptoms without delaying the progression of the disease. Therefore, there is an urgent need to develop a medicine that can delay the progression of AD or cure it. In recent years, increasing evidence suggests that metal complexes have the enormous potential to treat AD through inhibiting the aggregation and cytotoxicity of Aβ, interfering with the congregation and hyperphosphorylation of tau, regulating dysfunctional synaptic and unbalanced neurotransmitters, etc. In this review, we summarize the current metal complexes and their mechanisms of action for treating AD, including ruthenium, platinum, zinc, vanadium, copper, magnesium, and other complexes.

Sleep disorders and risk of alzheimer's disease: A two-way road

Substantial sleep impairment in patients with Alzheimer's disease (AD) is one of the emerging points for continued efforts to better understand the disease. Individuals without cognitive decline, an important marker of the clinical phase of AD, may show early alterations in the sleep-wake cycle. The objective of this critical narrative review is to explore the bidirectional pathophysiological correlation between sleep disturbances and Alzheimer's Disease. Specifically, it examines how the disruption of sleep homeostasis in individuals without dementia could contribute to the pathogenesis of AD, and conversely, how neurodegeneration in individuals with Alzheimer's Disease might lead to dysregulation of the sleep-wake cycle. Recent scientific results indicate that sleep disturbances, particularly those related to impaired glymphatic clearance, may act as an important mechanism associated with the genesis of Alzheimer's Disease. Additionally, amyloid deposition and tau protein hyperphosphorylation, along with astrocytic hyperactivation, appear to trigger changes in neurotransmission dynamics in areas related to sleep, which may explain the onset of sleep disturbances in individuals with AD. Disruption of sleep homeostasis appears to be a modifiable risk factor in Alzheimer's disease. Whenever possible, the use of non-pharmacological strategies becomes important in this context. From a different perspective, additional research is needed to understand and treat the dysfunction of the sleep-wake cycle in individuals already affected by AD. Early recognition and correction of sleep disturbances in this population could potentially mitigate the progression of dementia and improve the quality of life for those with AD.

Caloric restriction mimetics improve gut microbiota: a promising neurotherapeutics approach for managing age-related neurodegenerative disorders

The gut microbiota (GM) produces various molecules that regulate the physiological functionality of the brain through the gut-brain axis (GBA). Studies suggest that alteration in GBA may lead to the onset and progression of various neurological dysfunctions. Moreover, aging is one of the prominent causes that contribute to the alteration of GBA. With age, GM undergoes a shift in population size and species of microflora leading to changes in their secreted metabolites. These changes also hamper communications among the HPA (hypothalamic-pituitary-adrenal), ENS (enteric nervous system), and ANS (autonomic nervous system). A therapeutic intervention that has recently gained attention in improving health and maintaining communication between the gut and the brain is calorie restriction (CR), which also plays a critical role in autophagy and neurogenesis processes. However, its strict regime and lifelong commitment pose challenges. The need is to produce similar beneficial effects of CR without having its rigorous compliance. This led to an exploration of calorie restriction mimetics (CRMs) which could mimic CR's functions without limiting diet, providing long-term health benefits. CRMs ensure the efficient functioning of the GBA through gut bacteria and their metabolites i.e., short-chain fatty acids, bile acids, and neurotransmitters. This is particularly beneficial for elderly individuals, as the GM deteriorates with age and the body's ability to digest the toxic accumulates declines. In this review, we have explored the beneficial effect of CRMs in extending lifespan by enhancing the beneficial bacteria and their effects on metabolite production, physiological conditions, and neurological dysfunctions including neurodegenerative disorders.

The role of microglia in neurological diseases with involvement of extracellular vesicles

As a subset of mononuclear phagocytes in the central nervous system, microglia play a crucial role in immune defense and homeostasis maintenance. Microglia can regulate their states in response to specific signals of health and pathology. Microglia-mediated neuroinflammation is a pathological hallmark of neurodegenerative diseases, neurological damage and neurological tumors, underscoring its key immunoregulatory role in these conditions. Intriguingly, a substantial body of research has indicated that extracellular vesicles can mediate intercellular communication by transporting cargoes from parental cells, a property that is also reflected in microenvironmental signaling networks involving microglia. Based on the microglial characteristics, we briefly outline the biological features of extracellular vesicles and focus on summarizing the integrative role played by microglia in the maintenance of nervous system homeostasis and progression of different neurological diseases. Extracellular vesicles may engage in the homeostasis maintenance and pathological process as a medium of intercellular communication. Here, we aim to provide new insights for further exploration of neurological disease pathogenesis, which may provide theoretical foundations for cell-free therapies.

Down regulation of the c-Fos/MAP kinase signaling pathway during learning memory processes coincides with low GnRH levels in aluminum chloride-induced Alzheimer's male rats

Aluminum chloride (Al) is associated with Alzheimer's disease (AD) and reproductive disorders. But the relationship between gonadotropin-releasing hormone (GnRH) and c-Fos levels, the end product of MAP-kinase signaling, in AD is unknown, so we aimed to investigate this relationship. We exposed rats to Al dissolved in drinking water (10 and 50 mg/kg) for two and four weeks. The control group received only drinking water. At the end, the blood sample was collected under deep anesthesia and the brain was dissected on ice, and the testicular tissue was fixed in formalin. Amyloid beta (βA) plaques in brain regions and the number of CA1 neurons were evaluated by Congo red staining and cresyl violet staining. Activation of neuronal nitric oxide synthase (nNOS) was studied using NADPH-diaphorase. The levels of c-Fos and testosterone receptors in the target area were examined immunohistochemically. Brain GnRH levels were determined by blotting, and serum levels of gonadotropins and steroids were measured by enzyme-linked immunosorbent assay (ELISA). All data were analyzed using analysis of variance (ANOVA) at α = 0.05 level. The accumulation of βA plaque was observed along with a decrease in the number of CA1 pyramidal neurons and a significant decrease in the levels of c-Fos and GnRH in the brains of rats receiving Al, which was aligned with a significant decrease in serum levels of testosterone and LH. This study, for the first time, showed a link between dementia and a concomitant decrease in brain GnRH and c-Fos levels.

Corilagin improves cognitive impairment in APP/PS1 mice by reducing Aβ generation and enhancing synaptic plasticity

Alzheimer's disease (AD) is closely associated with the neurotoxic effects of amyloid-β (Aβ), leading to synaptic damage, neuronal loss and cognitive dysfunction. Previous in vitro studies have demonstrated the potential of corilagin to counteract Aβ-induced oxidative stress, inflammatory injury, and β-site amyloid precursor protein cleaving enzyme-1 (BACE1) activity in Aβ production. However, the in vivo protective effects of corilagin on Alzheimer's disease remain unexplored. The purpose of this study was to investigate the protective effects of corilagin on APP/PS1 mice and the underlying mechanisms. The cognitive function of the mice was assessed by step-through passive avoidance and Morris water maze tests. Nissl staining was used to evaluate neuronal damage in the hippocampus. ELISA and Western blotting analyses were used to determine the associated protein expression. Transmission electron microscopy was utilized to observe the synaptic ultrastructure of hippocampal neurons. Golgi staining was applied to assess dendritic morphology and dendritic spine density in hippocampal pyramidal neurons. Immunohistochemistry and Western blotting were performed to examine the expression of synaptic-associated proteins. The results showed that corilagin improves learning and memory in APP/PS1 mice, reduces hippocampal neuron damage, inhibits BACE1 and reduces Aβ generation. It also improves synaptic plasticity and the expression of synaptic-associated proteins. Corilagin effectively reduces Aβ generation by inhibiting BACE1, ultimately reducing neuronal loss and enhancing synaptic plasticity to improve synaptic transmission. This study sheds light on the potential therapeutic role of corilagin in Alzheimer's disease.

Nanomaterials that Aid in the Diagnosis and Treatment of Alzheimer's Disease, Resolving Blood-Brain Barrier Crossing Ability

As a form of dementia, Alzheimer's disease (AD) suffers from no efficacious cure, yet AD treatment is still imperative, as it ameliorates the symptoms or prevents it from deteriorating or maintains the current status to the longest extent. The human brain is the most sensitive and complex organ in the body, which is protected by the blood-brain barrier (BBB). This yet induces the difficulty in curing AD as the drugs or nanomaterials that are much inhibited from reaching the lesion site. Thus, BBB crossing capability of drug delivery system remains a significant challenge in the development of neurological therapeutics. Fortunately, nano-enabled delivery systems possess promising potential to achieve multifunctional diagnostics/therapeutics against various targets of AD owing to their intriguing advantages of nanocarriers, including easy multifunctionalization on surfaces, high surface-to-volume ratio with large payloads, and potential ability to cross the BBB, making them capable of conquering the limitations of conventional drug candidates. This review, which focuses on the BBB crossing ability of the multifunctional nanomaterials in AD diagnosis and treatment, will provide an insightful vision that is conducive to the development of AD-related nanomaterials.

Phosphatidylserine: A comprehensive overview of synthesis, metabolism, and nutrition

Phosphatidylserine (PtdS) is classified as a glycerophospholipid and a primary anionic phospholipid and is particularly abundant in the inner leaflet of the plasma membrane in neural tissues. It is synthesized from phosphatidylcholine or phosphatidylethanolamine by exchanging the base head group with serine, and this reaction is catalyzed by PtdS synthase-1 and PtdS synthase-2 located in the endoplasmic reticulum. PtdS exposure on the outside surface of the cell is essential for eliminating apoptotic cells and initiating the blood clotting cascade. It is also a precursor of phosphatidylethanolamine, produced by PtdS decarboxylase in bacteria, yeast, and mammalian cells. Furthermore, PtdS acts as a cofactor for several necessary enzymes that participate in signaling pathways. Beyond these functions, several studies indicate that PtdS plays a role in various cerebral functions, including activating membrane signaling pathways, neuroinflammation, neurotransmission, and synaptic refinement associated with the central nervous system (CNS). This review discusses the occurrence of PtdS in nature and biosynthesis via enzymes and genes in plants, yeast, prokaryotes, mammalian cells, and the brain, and enzymatic synthesis through phospholipase D (PLD). Furthermore, we discuss metabolism, its role in the CNS, the fortification of foods, and supplementation for improving some memory functions, the results of which remain unclear. PtdS can be a potentially beneficial addition to foods for kids, seniors, athletes, and others, especially with the rising consumer trend favoring functional foods over conventional pills and capsules. Clinical studies have shown that PtdS is safe and well tolerated by patients.

The role of neuron-like cell lines and primary neuron cell models in unraveling the complexity of neurodegenerative diseases: a comprehensive review

Neurodegenerative diseases (NDs) are characterized by the progressive loss of neurons. As to developing effective therapeutic interventions, it is crucial to understand the underlying mechanisms of NDs. Cellular models have become invaluable tools for studying the complex pathogenesis of NDs, offering insights into disease mechanisms, determining potential therapeutic targets, and aiding in drug discovery. This review provides a comprehensive overview of various cellular models used in ND research, focusing on Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Cell lines, such as SH-SY5Y and PC12 cells, have emerged as valuable tools due to their ease of use, reproducibility, and scalability. Additionally, co-culture models, involving the growth of distinct cell types like neurons and astrocytes together, are highlighted for simulating brain interactions and microenvironment. While cell lines cannot fully replicate the complexity of the human brain, they provide a scalable method for examining important aspects of neurodegenerative diseases. Advancements in cell line technologies, including the incorporation of patient-specific genetic variants and improved co-culture models, hold promise for enhancing our understanding and expediting the development of effective treatments. Integrating multiple cellular models and advanced technologies offers the potential for significant progress in unraveling the intricacies of these debilitating diseases and improving patient outcomes.

Mitochondria-targeting Cu2-xSe-TPP with dual enzyme activity alleviates Alzheimer's disease by modulating oxidative stress

Mitochondrial dysfunction in microglia has been implicated as a key pathogenesis of most neurodegenerative diseases including Alzheimer's disease (AD). Abnormal production of reactive oxygen species (ROS) and neuroinflammation caused by mitochondrial oxidative stress are important factors leading to neuronal death in AD. Herein, a "dual brake" strategy to synergistically halt mitochondrial dysfunction and neuroinflammation targeting mitochondria in microglia is proposed. To achieve this goal, (3-carboxypropyl) triphenyl-phosphonium bromide (TPP)-modified Cu2-xSe nanozymes (Cu2-xSe-TPP NPs) with dual enzyme-like activities was designed. Cu2-xSe-TPP NPs with superoxide dismutase-mimetic (SOD) and catalase-mimetic (CAT) activities can effectively scavenge ROS in the mitochondria of microglia and relieve mitochondrial oxidative stress. In vivo studies demonstrated that Cu2-xSe-TPP NPs can alleviate oxidative stress and promote neuroprotection in the hippocampus of AD model mice. In addition, Cu2-xSe-TPP NPs can regulate the polarization of microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, promote Aβ phagocytosis and reshape the AD inflammatory microenvironment, thus effectively attenuating AD neuropathology and rescuing cognitive deficits in AD model mice. Taken together, this strategy preventing mitochondrial damage and remodeling the inflammatory microenvironment will provide a new perspective for AD therapy.

Gut microbiota metabolites: potential therapeutic targets for Alzheimer's disease?

Background

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive decline in cognitive function, which significantly increases pain and social burden. However, few therapeutic interventions are effective in preventing or mitigating the progression of AD. An increasing number of recent studies support the hypothesis that the gut microbiome and its metabolites may be associated with upstream regulators of AD pathology.

Methods

In this review, we comprehensively explore the potential mechanisms and currently available interventions targeting the microbiome for the improvement of AD. Our discussion is structured around modern research advancements in AD, the bidirectional communication between the gut and brain, the multi-target regulatory effects of microbial metabolites on AD, and therapeutic strategies aimed at modulating gut microbiota to manage AD.

Results

The gut microbiota plays a crucial role in the pathogenesis of AD through continuous bidirectional communication via the microbiota-gut-brain axis. Among these, microbial metabolites such as lipids, amino acids, bile acids and neurotransmitters, especially sphingolipids and phospholipids, may serve as central components of the gut-brain axis, regulating AD-related pathogenic mechanisms including β-amyloid metabolism, Tau protein phosphorylation, and neuroinflammation. Additionally, interventions such as probiotic administration, fecal microbiota transplantation, and antibiotic use have also provided evidence supporting the association between gut microbiota and AD. At the same time, we propose an innovative strategy for treating AD: a healthy lifestyle combined with targeted probiotics and other potential therapeutic interventions, aiming to restore intestinal ecology and microbiota balance.

Conclusion

Despite previous efforts, the molecular mechanisms by which gut microbes act on AD have yet to be fully described. However, intestinal microorganisms may become an essential target for connecting the gut-brain axis and improving the symptoms of AD. At the same time, it requires joint exploration by multiple centers and multiple disciplines.

Involvement of ubiquitination in Alzheimer's disease

The hallmark pathological features of Alzheimer's disease (AD) consist of senile plaques, which are formed by extracellular β-amyloid (Aβ) deposition, and neurofibrillary tangles, which are formed by the hyperphosphorylation of intra-neuronal tau proteins. With the increase in clinical studies, the in vivo imbalance of iron homeostasis and the dysfunction of synaptic plasticity have been confirmed to be involved in AD pathogenesis. All of these mechanisms are constituted by the abnormal accumulation of misfolded or conformationally altered protein aggregates, which in turn drive AD progression. Proteostatic imbalance has emerged as a key mechanism in the pathogenesis of AD. Ubiquitination modification is a major pathway for maintaining protein homeostasis, and protein degradation is primarily carried out by the ubiquitin-proteasome system (UPS). In this review, we provide an overview of the ubiquitination modification processes and related protein ubiquitination degradation pathways in AD, focusing on the microtubule-associated protein Tau, amyloid precursor protein (APP), divalent metal transporter protein 1 (DMT1), and α-amino-3-hyroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors. We also discuss recent advances in ubiquitination-based targeted therapy for AD, with the aim of contributing new ideas to the development of novel therapeutic interventions for AD.

Exploring advancements in early detection of Alzheimer's disease with molecular assays and animal models

Alzheimer's Disease (AD) is a challenging neurodegenerative condition, with overwhelming implications for affected individuals and healthcare systems worldwide. Animal models have played a crucial role in studying AD pathogenesis and testing therapeutic interventions. Remarkably, studies on the genetic factors affecting AD risk, such as APOE and TREM2, have provided valuable insights into disease mechanisms. Early diagnosis has emerged as a crucial factor in effective AD management, as demonstrated by clinical studies emphasizing the benefits of initiating treatment at early stages. Novel diagnostic technologies, including RNA sequencing of microglia, offer promising avenues for early detection and monitoring of AD progression. Therapeutic strategies remain to evolve, with a focus on targeting amyloid beta (Aβ) and tau pathology. Advances in animal models, such as APP-KI mice, and the advancement of anti-Aβ drugs signify progress towards more effective treatments. Therapeutically, the focus has shifted towards intricate approaches targeting multiple pathological pathways simultaneously. Strategies aimed at reducing Aβ plaque accumulation, inhibiting tau hyperphosphorylation, and modulating neuroinflammation are actively being explored, both in preclinical models and clinical trials. While challenges continue in developing validated animal models and translating preclinical findings to clinical success, the continuing efforts in understanding AD at molecular, cellular, and clinical levels offer hope for improved management and eventual prevention of this devastating disease.