Amyloid Beta in Aging and Alzheimer's Disease

Emerging Trends: Neurofilament Biomarkers in Precision Neurology

Neurofilaments are structural proteins found in the cytoplasm of neurons, particularly in axons, providing structural support and stability to the axon. They consist of multiple subunits, including NF-H, NF-M, and NF-L, which form long filaments along the axon's length. Neurofilaments are crucial for maintaining the shape and integrity of neurons, promoting axonal transport, and regulating neuronal function. They are part of the intermediate filament (IF) family, which has approximately 70 tissue-specific genes. This diversity allows for a customizable cytoplasmic meshwork, adapting to the unique structural demands of different tissues and cell types. Neurofilament proteins show increased levels in both cerebrospinal fluid (CSF) and blood after neuroaxonal damage, indicating injury regardless of the underlying etiology. Precise measurement and long-term monitoring of damage are necessary for determining prognosis, assessing disease activity, tracking therapeutic responses, and creating treatments. These investigations contribute to our understanding of the importance of proper NF composition in fundamental neuronal processes and have implications for neurological disorders associated with NF abnormalities along with its alteration in different animal and human models. Here in this review, we have highlighted various neurological disorders such as Alzheimer's, Parkinson's, Huntington's, Dementia, and paved the way to use neurofilament as a marker in managing neurological disorders.

A systematic review of salivary biomarkers in Parkinson's disease

The search for reliable and easily accessible biomarkers in Parkinson's disease is receiving a growing emphasis, to detect neurodegeneration from the prodromal phase and to enforce disease-modifying therapies. Despite the need for non-invasively accessible biomarkers, the majority of the studies have pointed to cerebrospinal fluid or peripheral biopsies biomarkers, which require invasive collection procedures. Saliva represents an easily accessible biofluid and an incredibly wide source of molecular biomarkers. In the present study, after presenting the morphological and biological bases for looking at saliva in the search of biomarkers for Parkinson's disease, we systematically reviewed the results achieved so far in the saliva of different cohorts of Parkinson's disease patients. A comprehensive literature search on PubMed and SCOPUS led to the discovery of 289 articles. After screening and exclusion, 34 relevant articles were derived for systematic review. Alpha-synuclein, the histopathological hallmark of Parkinson's disease, has been the most investigated Parkinson's disease biomarker in saliva, with oligomeric alpha-synuclein consistently found increased in Parkinson's disease patients in comparison to healthy controls, while conflicting results have been reported regarding the levels of total alpha-synuclein and phosphorylated alpha-synuclein, and few studies described an increased oligomeric alpha-synuclein/total alpha-synuclein ratio in Parkinson's disease. Beyond alpha-synuclein, other biomarkers targeting different molecular pathways have been explored in the saliva of Parkinson's disease patients: total tau, phosphorylated tau, amyloid-β1-42 (pathological protein aggregation biomarkers); DJ-1, heme-oxygenase-1, metabolites (altered energy homeostasis biomarkers); MAPLC-3beta (aberrant proteostasis biomarker); cortisol, tumor necrosis factor-alpha (inflammation biomarkers); DNA methylation, miRNA (DNA/RNA defects biomarkers); acetylcholinesterase activity (synaptic and neuronal network dysfunction biomarkers); Raman spectra, proteome, and caffeine. Despite a few studies investigating biomarkers targeting molecular pathways different from alpha-synuclein in Parkinson's disease, these results should be replicated and observed in studies on larger cohorts, considering the potential role of these biomarkers in determining the molecular variance among Parkinson's disease subtypes. Although the need for standardization in sample collection and processing, salivary-based biomarkers studies have reported encouraging results, calling for large-scale longitudinal studies and multicentric assessments, given the great molecular potentials and the non-invasive accessibility of saliva.

Evidence for a role of human blood-borne factors in mediating age-associated changes in molecular circadian rhythms

Aging is associated with a number of physiologic changes including perturbed circadian rhythms; however, mechanisms by which rhythms are altered remain unknown. To test the idea that circulating factors mediate age-dependent changes in peripheral rhythms, we compared the ability of human serum from young and old individuals to synchronize circadian rhythms in culture. We collected blood from apparently healthy young (age 25-30) and old (age 70-76) individuals at 14:00 and used the serum to synchronize cultured fibroblasts. We found that young and old sera are equally competent at initiating robust ~24 hr oscillations of a luciferase reporter driven by clock gene promoter. However, cyclic gene expression is affected, such that young and old sera promote cycling of different sets of genes. Genes that lose rhythmicity with old serum entrainment are associated with oxidative phosphorylation and Alzheimer's Disease as identified by STRING and IPA analyses. Conversely, the expression of cycling genes associated with cholesterol biosynthesis increased in the cells entrained with old serum. Genes involved in the cell cycle and transcription/translation remain rhythmic in both conditions. We did not observe a global difference in the distribution of phase between groups, but found that peak expression of several clock-controlled genes (PER3, NR1D1, NR1D2, CRY1, CRY2, and TEF) lagged in the cells synchronized ex vivo with old serum. Taken together, these findings demonstrate that age-dependent blood-borne factors affect circadian rhythms in peripheral cells and have the potential to impact health and disease via maintaining or disrupting rhythms respectively.

Phytoactive drugs used in the treatment of Alzheimer's disease and dementia

The prevalence of Alzheimer's disease and other forms of dementia is increasing worldwide, and finding effective treatments for these conditions is a major public health challenge. Natural bioactive drugs have been identified as a promising source of potential treatments, due to their ability to target multiple pathways and their low toxicity. This paper reviews the current state of research on natural bioactive drugs used in the treatment of Alzheimer's disease and other dementias. The paper summarizes the findings of studies on various natural compounds, including curcumin, resveratrol, caffeine, genistein, quercetin, GinkoBiloba, Withaniasomnifera, Ginseng Brahmi, Giloy, and huperzine, and their effects on cognitive function, neuroinflammation, and amyloid-beta accumulation. In this review, we discuss the mechanism of action involved in the treatment of Alzheimer's disease. The paper also discusses the challenges associated with developing natural bioactive drugs for dementia treatment, including issues related to bioavailability and standardization. Finally, the paper suggests directions for future research in this area, including the need for more rigorous clinical trials and the development of novel delivery systems to improve the efficacy of natural bioactive drugs. Overall, this review highlights the potential of natural bioactive drugs as a promising avenue for the development of safe and effective treatments for Alzheimer's disease and other dementias.

14-3-3 protein and its isoforms: A common diagnostic marker for Alzheimer's disease, Parkinson's disease and glaucomatous neurodegeneration

There is a molecular coupling between neurodegenerative diseases, including glaucomatous neurodegeneration (GN), Alzheimer's disease (AD), and Parkinson's disease (PD). Many cells in the eye and the brain have the right amount of 14-3-3 proteins (14-3-3s) and their isoforms, such as β, ε, γ, η, θ, π, and γ. These cells include keratocytes, endothelial cells, corneal epithelial cells, and primary conjunctival epithelial cells. 14-3-3s regulate autophagy and mitophagy, help break down built-up proteins, and connect to other proteins to safeguard against neurodegeneration in AD, PD, GN, and glioblastoma. By interacting with these proteins, 14-3-3s stop Bad and Bax proteins from entering mitochondria and make Bcl-2 less effective. These interactions inhibit neuronal apoptosis. They play many important roles in managing the breakdown of lysosomal proteins, tau, and Aβ, which is why the 14-3-3s could be used as therapeutic targets in AD. Furthermore, researchers have discovered 14-3-3s in Lewy bodies, which are associated with various proteins like LRRK2, ASN, and Parkin, all of which play a role in developing Parkinson's disease (PD). The 14-3-3s influence the premature aging and natural wrinkles of human skin. Studies have shown that lowering 14-3-3s in the brain can lead to an increase in cell-death proteins like BAX and ERK, which in turn causes excitotoxicity-induced neurodegeneration. This review aimed to clarify the role of 14-3-3s in the neuropathology of AD, PD, and GN, as well as potential diagnostic markers for improving neuronal survival and repair.

The Role of Exercise in the Prevention and Treatment of Alzheimer's Disease and Mild Cognitive Impairments

Large retrospective cohort studies have consistently shown that people who exercise regularly are at a markedly reduced risk of dementias such as Alzheimer's Disease (AD). Animal studies have also found that exercise can prevent cognitive decline, and recent studies have identified possible mechanisms. However, randomized controlled trials of exercise interventions in AD and mild cognitive impairment have not reached a consensus regarding the efficacy of this treatment, hampering clinical adoption of this technique. This review examines these randomized controlled trials to assess potential causes for the variability in the measured outcomes. We posit that great variance in the methods used in these studies may account for some of the differences seen in outcomes. We determined that aerobic exercise led to the most benefits, that many cognitive domains improve with exercise, and that aerobic exercise enhances the ability for independent living. However, cognitive improvements were more pronounced and consistent in patients with mild cognitive impairment than AD, suggesting a narrow window of opportunity for exercise intervention.

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.

Surface engineered nano architectonics: An evolving paradigm for tackling Alzheimer's disease

As per the World Health Organization (WHO) estimation, Alzheimer's disease (AD) will affect 100 million population across the globe by 2050. AD is an incurable neurodegenerative disease that remains a mystery for neurologists owing to its complex pathophysiology. Currently, available therapeutic regimens will only cause symptomatic relief by improving the cognitive and behavioral functions of AD. However, the major pitfalls in managing AD include tight junctions in the endothelial cells of the blood-brain barrier (BBB), diminished neuronal bioavailability, enzymatic degradation and reduced stability of the therapeutic moiety. In an effort to surmount the drawbacks mentioned above, researchers shifted their focus toward nanocarriers (NCs). Nevertheless, non-specific targeting of NCs imparts toxicity to the peripheral organs, thereby reducing the bioavailability of therapeutic moiety at the target site. To unravel this unmet clinical need, scientists came up with the idea of a novel intriguing strategy of surface engineering by targeting ligands. Surface-decorated NCs provide targeted drug delivery, controlled drug release, enhanced penetration and bioavailability. In this state-of-the-art review, we have highlighted in detail various molecular signalling pathways involved in AD pathogenesis. The significance of surface functionalization and its application in AD management have been deliberated. We have elaborated on the regulatory bottlenecks and clinical hurdles faced during lab-to-industrial scale translation along with possible solutions.

The role of sirtuin 1 in ageing and neurodegenerative disease: A molecular perspective

Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, has emerged as a key regulator of cellular processes linked to ageing and neurodegeneration. SIRT1 modulates various signalling pathways, including those involved in autophagy, oxidative stress, and mitochondrial function, which are critical in the pathogenesis of neurodegenerative diseases. This review explores the therapeutic potential of SIRT1 in several neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic Lateral Sclerosis (ALS). Preclinical studies have demonstrated that SIRT1 activators, such as resveratrol, SRT1720, and SRT2104, can alleviate disease symptoms by reducing oxidative stress, enhancing autophagic flux, and promoting neuronal survival. Ongoing clinical trials are evaluating the efficacy of these SIRT1 activators, providing hope for future therapeutic strategies targeting SIRT1 in neurodegenerative diseases. This review explores the role of SIRT1 in ageing and neurodegenerative diseases, with a particular focus on its molecular mechanisms, therapeutic potential, and clinical applications.

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.

Pentacyclic triterpenes as bioactive compounds isolated from Mauritia flexuosa L. f. acting against the Alzheimer's disease

Alzheimer's disease is a significant concern due to its high prevalence and the limitations of current treatments. In our research, we investigated Mauritia flexuosa, a medicinal plant traditionally used for headaches, to identify active compounds with potential anti-Alzheimer's effects. Three pentacyclic triterpenes were isolated through column chromatography and characterised from the dichloromethane/methanol extract from Mauritia flexuosa (DCMEMf), with (3β)-3-hydroxy-11-oxours-12-en-28-oic acid (3) showing the highest in vitro activity in the HMC3 and SVG p12 cell lines. Compound 3 inhibited the pharmacological targets NF-κB, PGE2, IDO1, and EGFR with IC50 values of 9.83, 3.86, 1.63 μM, and 49.57 nM, respectively, attributed to a hydroxyl group at the C-3 position of its structure. These findings suggest the potential of these compounds in treating neurological diseases, including headaches, and offer promising prospects for the development of new therapies against Alzheimer's.

METTL14 inhibits Aβ1-42-induced neuronal injury through regulating the stability of CBLN4 mRNA in Alzheimer's disease

Previous studies have suggested that N6-methyladenosine (mA) modification of RNA affects fundamental aspects of RNA metabolism, and mA dysregulation is implicated in various human diseases, including Alzheimer's disease (AD). This study is designed to explore the role and mechanism of methyltransferase-like 14 (METTL14) in the pathogenesis of AD. SK-N-SH cells were treated with Aβ1-42 to establish an in vitro model of AD. Cerebellin 4 (CBLN4) and METTL14 expression levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell viability and apoptosis were analyzed using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry assay. B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), C-caspase-3, total-caspase-3, C/EBP homologous protein (CHOP), and glucose-related protein 78 (GRP78) protein levels were determined using Western blot. Interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α) levels were analyzed using ELISA. Reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD) products were examined using special assay kits. Interaction between CBLN4 and METTL14 was verified using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assays. CBLN4 and METTL14 expression was decreased in Aβ1-42-treated SK-N-SH cells. Upregulation of CBLN4 relieved Aβ1-42-induced SK-N-SH cell apoptosis, inflammation, oxidative stress, and endoplasmic reticulum (ER) stress in vitro. At the molecular level, METTL14 could improve the stability and expression of CBLN4 mRNA via m6A methylation. Our findings indicated that m6A methylase METTL14-mediated upregulation of CBLN4 mRNA stability could repress Aβ1-42-triggered SK-N-SH cell injury, providing a promising therapeutic target for AD treatment.

Type 2 diabetes mellitus and neurodegenerative disorders: The mitochondrial connection

The incidence of type 2 diabetes mellitus (T2DM) has increased in our society in recent decades as the population ages, and this trend is not expected to revert. This is the same for the incidence of the main neurodegenerative disorders, including the two most common ones, which are, Alzheimer's and Parkinson's disease. Currently, no pharmacological therapies have been developed to revert or cure any of these pathologies. Interestingly, in recent years, an increased number of studies have shown a high co-morbidity between T2DM and neurodegeneration, as well as some common molecular pathways that are affected in both types of diseases. For example, while the etiopathology of T2DM and neurodegenerative disorders is highly complex, mitochondrial dysfunction has been broadly described in the early steps of both diseases; accordingly, this dysfunction has emerged as a plausible molecular link between them. In fact, the prominent role played by mitochondria in the mammalian metabolism of glucose places the physiology of the organelle in a central position to regulate many cellular processes that are affected in both T2DM and neurodegenerative disorders. In this collaborative review, we critically describe the relationship between T2DM and neurodegeneration; making a special emphasis on the mitochondrial mechanisms that could link these diseases. A better understanding of the role of mitochondria on the etiopathology of T2DM and neurodegeneration could pave the way for the development of new pharmacological therapies focused on the regulation of the physiology of the organelle. These therapies could, ultimately, contribute to increase healthspan.

Evaluating the safety and efficiency of nanomaterials: A focus on mitochondrial health

Nanomaterials (NMs) have extensive application potential in drug delivery, tissue engineering, and various other domains, attributable to their exceptional physical and chemical properties. Nevertheless, an increasing body of literature underscores the diverse safety risks are associated with NMs upon interaction with the human body, including oxidative stress and programmed cell death. Mitochondria, serving as cellular energy factories, play a pivotal role in energy metabolism and the regulation of cell fate. Organs with substantial energy demands, including the heart and brain, are highly sensitive to mitochondrial integrity, with mitochondrial impairment potentially resulting in significant dysfunction and pathologies such as as heart failure and neurodegenerative disease. This review elucidates the pathways by which NMs translocate into mitochondria, their intracellular dynamics, and their impact on mitochondrial morphology, respiratory chain activity, and metabolic processes. We further investigate associated molecular mechanisms, including mitochondrial dynamic imbalance, calcium overload, and oxidative stress, and elucidate the pivotal roles of mitochondria in different forms of programmed cell death such as apoptosis and autophagy. Finally, we offer recommendations regarding the safety and efficacy of NMs for medical applications. By systematically analyzing the interactions and molecular mechanisms between NMs and mitochondria, this paper aims to enhance the toxicological evaluation framework of NMs and provide a foundational reference and theoretical basis for their clinical utilization.

Exploring cuproptosis-related molecular clusters and immunological characterization in ischemic stroke through machine learning

Objective

Ischemic stroke (IS) is a significant health concern with high disability and fatality rates despite available treatments. Immune cells and cuproptosis are associated with the onset and progression of IS. Investigating the interaction between cuproptosis-related genes (CURGs) and immune cells in IS can provide a theoretical basis for IS treatment.

Methods

We obtained IS datasets from the Gene Expression Omnibus (GEO) and employed machine learning to identify CURGs. The diagnostic efficiency of the CURGs was evaluated using receiver operating characteristic (ROC) curves. KEGG and gene set enrichment analysis (GSEA) were also conducted to identify biologically relevant pathways associated with CURGs in IS patients. Single-cell analysis was used to confirm the expression of 19 CURGs, and pathway activity calculations were performed using the AUCell package. Additionally, a risk prediction model for IS patients was developed, and core modules and hub genes related to IS were identified using weighted gene coexpression network analysis (WGCNA). We classified IS patients using a method of consensus clustering.

Results

We established a precise diagnostic model for IS. Enrichment analysis revealed major pathways, including oxidative phosphorylation, the NF-kappa B signaling pathway, the apoptosis pathway, and the Wnt signaling pathway. At the single-cell level, compared to those in non-IS samples, 19 CURGs were primarily overexpressed in the immune cells of IS samples and exhibited high activity in natural killer cell-mediated cytotoxicity, steroid hormone biosynthesis, and oxidative phosphorylation. Two clusters were obtained through consensus clustering. Notably, immune cell types including B cells, plasma cells, and resting NK cells, varied between the two clusters. Furthermore, the red module and hub genes associated with IS were uncovered. The expression patterns of CURGs varied over time.

Conclusion

This study developed a precise diagnostic model for IS by identifying CURGs and evaluating their interaction with immune cells. Enrichment analyses revealed key pathways involved in IS, and single-cell analysis confirmed CURG overexpression in immune cells. A risk prediction model and core modules associated with IS were also identified.

From Brain to Muscle: The Role of Muscle Tissue in Neurodegenerative Disorders

Neurodegenerative diseases (NDs), like amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and Parkinson's disease (PD), primarily affect the central nervous system, leading to progressive neuronal loss and motor and cognitive dysfunction. However, recent studies have revealed that muscle tissue also plays a significant role in these diseases. ALS is characterized by severe muscle wasting as a result of motor neuron degeneration, as well as alterations in gene expression, protein aggregation, and oxidative stress. Muscle atrophy and mitochondrial dysfunction are also observed in AD, which may exacerbate cognitive decline due to systemic metabolic dysregulation. PD patients exhibit muscle fiber atrophy, altered muscle composition, and α-synuclein aggregation within muscle cells, contributing to motor symptoms and disease progression. Systemic inflammation and impaired protein degradation pathways are common among these disorders, highlighting muscle tissue as a key player in disease progression. Understanding these muscle-related changes offers potential therapeutic avenues, such as targeting mitochondrial function, reducing inflammation, and promoting muscle regeneration with exercise and pharmacological interventions. This review emphasizes the importance of considering an integrative approach to neurodegenerative disease research, considering both central and peripheral pathological mechanisms, in order to develop more effective treatments and improve patient outcomes.

Use and Reuse of Animal Behavioral, Molecular, and Biochemical Data in Alzheimer's Disease Research: Focus on 3Rs and Saving People's Tax Dollars

Several decades of research on cell and animal models contributed tremendously to understanding human diseases. Particularly, research on rodents and non-human primates revealed that animal research is a major and important component in biomedical research in learning complex pathophysiological processes. Further, animal research helped us to understand human diseases, such as Alzheimer's disease. In addition, animal research has also helped us to test hundreds of drugs and develop treatments for human use. Researchers can gain a better understanding of key biological and physiological processes in humans by comparing them to laboratory animals. Based on their relevance and resemblance to people, or even usual living conditions, scientists rationalize the use of particular animal models in their studies. It is suggested that in the National Institutes of Health and other agencies-funded research, animal models should be carefully selected to study the biology and pathophysiology of human health and diseases such as Alzheimer's disease and other dementias. However, it is critical to use a minimum number of animals for human research. Further, it is also noted that the use and reuse of behavioral,  molecular, and biochemical data from wild-type (WT) control mice with mutant lines of disease models, as long as the genetic background is the same in both WT and disease mice. On the other hand, anonymous readers have challenged the use and reuse of WT mice data for comparison. In the current article, we discuss the minimum utility of animals, covering the 3Rs, Replacement, Reduction, and Refinement, and also discuss the use and reuse of behavioral, molecular, and biochemical data.

Taming neuroinflammation in Alzheimer's disease: The protective role of phytochemicals through the gut-brain axis

Alzheimer's disease (AD) is a progressive degenerative neurological condition characterized by cognitive decline, primarily affecting memory and logical thinking, attributed to amyloid-β plaques and tau protein tangles in the brain, leading to neuronal loss and brain atrophy. Neuroinflammation, a hallmark of AD, involves the activation of microglia and astrocytes in response to pathological changes, potentially exacerbating neuronal damage. The gut-brain axis is a bidirectional communication pathway between the gastrointestinal and central nervous systems, crucial for maintaining brain health. Phytochemicals, natural compounds found in plants with antioxidant and anti-inflammatory properties, such as flavonoids, curcumin, resveratrol, and quercetin, have emerged as potential modulators of this axis, suggesting implications for AD prevention. Intake of phytochemicals influences the gut microbial composition and its metabolites, thereby impacting neuroinflammation and oxidative stress in the brain. Consumption of phytochemical-rich foods may promote a healthy gut microbiota, fostering the production of anti-inflammatory and neuroprotective substances. Early dietary incorporation of phytochemicals offers a non-invasive strategy for modulating the gut-brain axis and potentially reducing AD risk or delaying its onset. The exploration of interventions targeting the gut-brain axis through phytochemical intake represents a promising avenue for the development of preventive or therapeutic strategies against AD initiation and progression.

Mechanisms, consequences and role of interventions for sleep deprivation: Focus on mild cognitive impairment and Alzheimer's disease in elderly

Sleep is established as an essential physiological need that impacts physical, emotional, and cognitive functions profoundly. Physiologically, inadequate sleep weakens immune function, heightening susceptibility to infections and chronic illnesses such as obesity, diabetes, and cardiovascular diseases. Hormonal disruptions due to sleep loss further exacerbate metabolic dysregulation, contributing to weight gain and other health complications. Emotionally, sleep deprivation leads to mood disturbances, including increased irritability, heightened stress responses, and a greater likelihood of mood disorders like depression and anxiety. These effects are compounded by cognitive impairments such as reduced alertness, impaired memory consolidation, and compromised decision-making abilities, akin to the impairments caused by alcohol consumption. Motor skills and coordination also suffer, elevating the risk of accidents, particularly in high-stress environments. For older adults, sleep quality is closely linked to cognitive function and overall longevity. Optimal sleep patterns are associated with slower brain aging and improved health outcomes. However, sleep disorders exacerbate existing conditions such as epilepsy and asthma, necessitating interventions like cognitive behavioral therapy (CBT) and medications such as melatonin to mitigate their impact. Education emerges as a crucial tool in promoting healthier sleep habits across all age groups. Addressing misconceptions about sleep and integrating sleep health into public health policies are essential steps toward improving overall well-being. Additionally, lifestyle factors such as diet and physical activity play significant roles in regulating sleep patterns, further emphasizing the interconnectedness of sleep with broader health outcomes. In summary, the articles underscore the intricate mechanisms through which sleep influences physiological functions and advocate for comprehensive approaches to enhance sleep hygiene and mitigate the adverse effects of sleep deprivation on human health.

MicroRNA-455-3P as a peripheral biomarker and therapeutic target for mild cognitive impairment and Alzheimer's disease

MicroRNAs are small non-coding RNAs evolutionary conserved molecules. They regulate cellular processes, including RNA silencing, post-translational gene expression and neurodegeneration. MicroRNAs are involved with human diseases such as cancer, Alzheimer's disease (AD) and others. Interestingly, cerebrospinal fluids (CSF) and the blood of AD patients have altered expressions of many RNAs, which may serve as potential peripheral biomarkers. The intensive investigation from our lab revealed that microRNA-455-3 P (miR-455-3p) is a strong candidate as a potential biomarker and therapeutic target for AD. Several genes implicated in the pathogenesis of AD are directly targeted by miR-455-3p. Several years of our lab research revealed that miR-455-3p regulates important physiological processes associated with AD, such as the processing of the amyloid precursor protein (APP), TGF-β signaling, the regulation of oxidative stress, mitochondrial biogenesis, and synaptic damages. The expression of miR-455-3p in mild cognitive impaired subjects and AD patients pointed out its involvement in AD progression. Recently, our lab generated both transgenic and knockout mice for miR-455-3p. Interestingly miR-455-3p transgenic mice showed superior cognitive learning, improved memory and extended lifespan compared to age matched wild-type mice, whereas miR-455-3-p knockout mice showed cognitive decline and reduced lifespan. Information derived from mouse models further demonstrated the advantageous impact of miR-455-3p on dendritic growth, synaptogenesis, and mitochondrial biogenesis in preventing the onset and progression of AD. The identification of miR-455-3p as a biomarker was suggested by its presence in postmortem AD brains, B-lymphocytes, and fibroblasts. Our hypothesis that miR-455-3p could be a peripheral biomarker and therapeutic target for AD.

Inhibition of CXCR4: A perspective on miracle fruit seed for Alzheimer's disease treatment

Alzheimer's disease (AD) is the most prevalent type of dementia, and its causes are currently diverse and not fully understood. In a previous study, we discovered that short-term treatment with miracle fruit seed (MFS) had a therapeutic effect on AD model mice, however, the precise mechanism behind the effect remains unclear. In this research, we aimed to establish the efficacy and safety of long-term use of MFS in AD model mice. A variety of cytokines and chemokines have been implicated in the development of AD. Previous studies have validated a correlation between the expression levels of C-X-C chemokine receptor type 4 (CXCR4) and disease severity in AD. In this research, we observed an upregulation of CXCR4 expression in hippocampal tissues in the AD model group, which was then reversed after MFS treatment. Moreover, CXCR4 knockout led to improving cognitive function in AD model mice, and MFS showed the ability to regulate CXCR4 expression. Finally, our findings indicate that CXCR4 knockout and long-term MFS treatment produce comparable effects in treating AD model mice. In conclusion, this research demonstrates that therapeutic efficacy and safety of long-term use of MFS in AD model mice. MFS treatment and the subsequent reduction of CXCR4 expression exhibit a neuroprotective role in the brain, highlighting their potential as therapeutic targets for AD.

Interplay between the glymphatic system and neurotoxic proteins in Parkinson's disease and related disorders: current knowledge and future directions

Parkinson's disease is a common neurodegenerative disorder that is associated with abnormal aggregation and accumulation of neurotoxic proteins, including α-synuclein, amyloid-β, and tau, in addition to the impaired elimination of these neurotoxic protein. Atypical parkinsonism, which has the same clinical presentation and neuropathology as Parkinson's disease, expands the disease landscape within the continuum of Parkinson's disease and related disorders. The glymphatic system is a waste clearance system in the brain, which is responsible for eliminating the neurotoxic proteins from the interstitial fluid. Impairment of the glymphatic system has been proposed as a significant contributor to the development and progression of neurodegenerative disease, as it exacerbates the aggregation of neurotoxic proteins and deteriorates neuronal damage. Therefore, impairment of the glymphatic system could be considered as the final common pathway to neurodegeneration. Previous evidence has provided initial insights into the potential effect of the impaired glymphatic system on Parkinson's disease and related disorders; however, many unanswered questions remain. This review aims to provide a comprehensive summary of the growing literature on the glymphatic system in Parkinson's disease and related disorders. The focus of this review is on identifying the manifestations and mechanisms of interplay between the glymphatic system and neurotoxic proteins, including loss of polarization of aquaporin-4 in astrocytic endfeet, sleep and circadian rhythms, neuroinflammation, astrogliosis, and gliosis. This review further delves into the underlying pathophysiology of the glymphatic system in Parkinson's disease and related disorders, and the potential implications of targeting the glymphatic system as a novel and promising therapeutic strategy.

Quercetin ameliorates neuroinflammatory and neurodegenerative biomarkers in the brain and improves neurobehavioral parameters in a repeated intranasal amyloid-beta exposed model of Alzheimer's disease

Objectives: The aim of the present study was to study the potential therapeutic effects of quercetin in protection against repeated intranasal exposure of an amyloid-beta-induced mouse model. Methods: Mice received intranasal Aβ1-42 (5 μg/10 μL) exposure once daily for seven consecutive days. Quercetin was orally administered to them at 30 mg kg-1 and 100 mg kg-1 doses for one week starting from day five following Aβ1-42 peptide administration. Following this, the animals were evaluated for neurobehavioral parameters using a Morris water maze test and a novel object recognition test. Further to this, the biomarkers for neuroinflammation and neurodegeneration were evaluated in the hippocampus and cortex regions of the brain in these animals. Results: Multiple exposures to intranasal Aβ led to a significant decline in the learning and cognitive memory of the animals, whereas oral treatment with quercetin at dosages of 30 and 100 mg kg-1 alleviated Aβ-induced effects. Quercetin treatment significantly reduced Aβ accumulation, oxidative stress and proinflammatory cytokine biomarkers in the brain. In addition, it also alleviated the activation of astrocytic biomarkers, amyloid precursor protein and phosphorylated-tau proteins in the brain. Conclusion: Quercetin was found to be a potent antioxidant, anti-inflammatory compound with protection against neurodegenerative damage and improved learning and cognitive memory in a repeated Aβ-exposure model of AD.

Anthocyanin-Rich Fraction of Black Rice Bran Extract Protects against Amyloid β-Induced Oxidative Stress, Endoplasmic Reticulum Stress, and Neuronal Apoptosis in SK-N-SH Cells

Alzheimer's disease (AD) is the most common neurodegenerative disorder in the aging population. An accumulation of amyloid plaques and neurofibrillary tangles causes degeneration of neurons, leading to neuronal cell death. The anthocyanin-rich fraction of black rice (Oryza sativa L. variety "Luem Pua") bran (AFBRB), extracted using a solution of ethanol and water and fractionated using Amberlite XAD7HP column chromatography, contains a high anthocyanin content (585 mg of cyanidin-3-O-glucoside and 24 mg of peonidin-3-O-glucoside per gram of the rich extract), which has been found to reduce neurodegeneration. This study focused on the neuroprotective effects of AFBRB in Aβ25-35-induced toxicity in the human neuroblastoma cell line (SK-N-SH). SK-N-SH was exposed to Aβ25-35 (10 µM) to induce an AD cell model in vitro. Pretreatment with AFBRB (0.1, 1, or 10 µg/mL) or C3G (20 µM) was conducted for 2 h prior to the treatment with Aβ25-35 (10 µM) for an additional 24 h. The results indicate that AFBRB can protect against the cytotoxic effect of Aβ25-35 through attenuation of intracellular ROS production, downregulation of the expression of the proteins Bax, cytochrome c, cleaved caspase-9, and cleaved caspase-3, upregulation of the expression of Bcl-2 in the mitochondrial death pathway, and reduction in the expression of the three major markers of ER stress pathways in similar ways. Interestingly, we found that pretreatment with AFBRB significantly alleviated Aβ-induced oxidative stress, ER stress, and apoptosis in SK-N-SH cells. This suggests that AFBRB might be a potential therapeutic agent in preventing neurodegenerative diseases.

TDP-43 Promotes Amyloid-Beta Toxicity by Delaying Fibril Maturation via Direct Molecular Interaction

Amyloid-β (Aβ) is a peptide that undergoes self-assembly into amyloid fibrils, which compose the hallmark plaques observed in Alzheimer's disease (AD). TAR DNA-binding protein 43 (TDP-43) is a protein with mislocalization and aggregation implicated in amyotrophic lateral sclerosis and other neurodegenerative diseases. Recent work suggests that TDP-43 may interact with Aβ, inhibiting the formation of amyloid fibrils and worsening AD pathology, but the molecular details of their interaction remain unknown. Using all-atom discrete molecular dynamics simulations, we systematically investigated the direct molecular interaction between Aβ and TDP-43. We found that Aβ monomers were able to bind near the flexible nuclear localization sequence of the N-terminal domain (NTD) of TDP-43, adopting β-sheet rich conformations that were promoted by the interaction. Furthermore, Aβ associated with the nucleic acid binding interface of the tandem RNA recognition motifs of TDP-43 via electrostatic interactions. Using the computational peptide array method, we found the strongest C-terminal domain interaction with Aβ to be within the amyloidogenic core region of TDP-43. With experimental evidence suggesting that the NTD is necessary for inhibiting Aβ fibril growth, we also simulated the NTD with an Aβ40 fibril seed. We found that the NTD was able to strongly bind the elongation surface of the fibril seed via extensive hydrogen bonding and could also diffuse along the lateral surface via electrostatic interactions. Our results suggest that TDP-43 binding to the elongation surface, thereby sterically blocking Aβ monomer addition, is responsible for the experimentally observed inhibition of fibril growth. We conclude that TDP-43 may promote Aβ toxicity by stabilizing the oligomeric state and kinetically delaying fibril maturation.

Monomeric and oligomeric amyloid-β cause distinct Alzheimer's disease pathophysiological characteristics in astrocytes in human glymphatics-on-chip models

Alzheimer's disease (AD) is marked by the aggregation of extracellular amyloid-β (Aβ) and astrocyte dysfunction. For Aβ oligomers or aggregates to be formed, there must be Aβ monomers present; however, the roles of monomeric Aβ (mAβ) and oligomeric Aβ (oAβ) in astrocyte pathogenesis are poorly understood. We cultured astrocytes in a brain-mimicking three-dimensional (3D) extracellular matrix and revealed that both mAβ and oAβ caused astrocytic atrophy and hyper-reactivity, but showed distinct Ca2+ changes in astrocytes. This 3D culture evolved into a microfluidic glymphatics-on-chip model containing astrocytes and endothelial cells with the interstitial fluid (ISF). The glymphatics-on-chip model not only reproduced the astrocytic atrophy, hyper-reactivity, and Ca2+ changes induced by mAβ and oAβ, but recapitulated that the components of the dystrophin-associated complex (DAC) and aquaporin-4 (AQP4) were properly maintained by the ISF, and dysregulated by mAβ and oAβ. Collectively, mAβ and oAβ cause distinct AD pathophysiological characteristics in the astrocytes.

Does the liver facilitate aging-related cognitive impairment: Conversation between liver and brain during exercise?

Liver, an important regulator of metabolic homeostasis, is critical for healthy brain function. In particular, age-related neurodegenerative diseases seriously reduce the quality of life for the elderly. As population aging progresses rapidly, unraveling the mechanisms that effectively delay aging has become critical. Appropriate exercise is reported to improve aging-related cognitive impairment. Whereas current studies focused on exploring the effect of exercise on the aging brain itself, ignoring the persistent effects of peripheral organs on the brain through the blood circulation. The aim of this paper is to summarize the communication and aging processes of the liver and brain and to emphasize the metabolic mechanisms of the liver-brain axis about exercise ameliorating aging-related neurodegenerative diseases. A comprehensive understanding of the potential mechanisms about exercise ameliorating aging is critical for improving adaptation to age-related brain changes and formulating effective interventions against age-related cognitive decline.

Effect of Sacubitril/Valsartan on Cognitive Function in Patients With Heart Failure With Preserved Ejection Fraction: A Prespecified Analysis of PARAGON-HF

BACKGROUND

A hypothetical concern has been raised that sacubitril/valsartan might cause cognitive impairment because neprilysin is one of several enzymes degrading amyloid-β peptides in the brain, some of which are neurotoxic and linked to Alzheimer-type dementia. To address this, we examined the effect of sacubitril/valsartan compared with valsartan on cognitive function in patients with heart failure with preserved ejection fraction in a prespecified substudy of PARAGON-HF (Prospective Comparison of Angiotensin Receptor Neprilysin Inhibitor With Angiotensin Receptor Blocker Global Outcomes in Heart Failure With Preserved Ejection Fraction).

METHODS

In PARAGON-HF, serial assessment of cognitive function was conducted in a subset of patients with the Mini-Mental State Examination (MMSE; score range, 0-30, with lower scores reflecting worse cognitive function). The prespecified primary analysis of this substudy was the change from baseline in MMSE score at 96 weeks. Other post hoc analyses included cognitive decline (fall in MMSE score of ≥3 points), cognitive impairment (MMSE score <24), or the occurrence of dementia-related adverse events.

RESULTS

Among 2895 patients included in the MMSE substudy with baseline MMSE score measured, 1453 patients were assigned to sacubitril/valsartan and 1442 to valsartan. Their mean age was 73 years, and the median follow-up was 32 months. The mean±SD MMSE score at randomization was 27.4±3.0 in the sacubitril/valsartan group, with 10% having an MMSE score <24; the corresponding numbers were nearly identical in the valsartan group. The mean change from baseline to 96 weeks in the sacubitril/valsartan group was -0.05 (SE, 0.07); the corresponding change in the valsartan group was -0.04 (0.07). The mean between-treatment difference at week 96 was -0.01 (95% CI, -0.20 to 0.19; P=0.95). Analyses of a ≥3-point decline in MMSE, decrease to a score <24, dementia-related adverse events, and combinations of these showed no difference between sacubitril/valsartan and valsartan. No difference was found in the subgroup of patients tested for apolipoprotein E ε4 allele genotype.

CONCLUSIONS

Patients with heart failure with preserved ejection fraction in PARAGON-HF had relatively low baseline MMSE scores. Cognitive change, measured by MMSE, did not differ between treatment with sacubitril/valsartan and treatment with valsartan in patients with heart failure with preserved ejection fraction.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01920711.

Computational Design of Novel Tau-Tubulin Kinase 1 Inhibitors for Neurodegenerative Diseases

The tau-tubulin kinase 1 (TTBK1) protein is a casein kinase 1 superfamily member located at chromosome 6p21.1. It is expressed explicitly in the brain, particularly in the cytoplasm of cortical and hippocampal neurons. TTBK1 has been implicated in the phosphorylation and aggregation of tau in Alzheimer's disease (AD). Considering its significance in AD, TTBK1 has emerged as a promising target for AD treatment. In the present study, we identified novel TTBK1 inhibitors using various computational techniques. We performed a virtual screening-based docking study followed by E-pharmacophore modeling, cavity-based pharmacophore, and ligand design techniques and found ZINC000095101333, LD7, LD55, and LD75 to be potential novel TTBK1 lead inhibitors. The docking results were complemented by Molecular Mechanics/Generalized Born Surface Area (MMGBSA) calculations. The molecular dynamics (MD) simulation studies at a 500 ns scale were carried out to monitor the behavior of the protein toward the identified ligands. Pharmacological and ADME/T studies were carried out to check the drug-likeness of the compounds. In summary, we identified a new series of compounds that could effectively bind the TTBK1 receptor. The newly designed compounds are promising candidates for developing therapeutics targeting TTBK1 for AD.

The role of AMPKα subunit in Alzheimer's disease: In-depth analysis and future prospects

The AMP-activated protein kinase α (AMPKα) subunit is the catalytic subunit in the AMPK complex, playing a crucial role in AMPK activation. It has two isoforms: AMPKα1 and AMPKα2. Emerging evidence suggests that the AMPKα subunit exhibits subtype-specific effects in Alzheimer's disease (AD). This review discusses the role of the AMPKα subunit in the pathogenesis of AD, including its impact on β-amyloid (Aβ) pathology, Tau pathology, metabolic disorders, inflammation, mitochondrial dysfunction, inflammasome and pyroptosis. Additionally, it reviews the distinct roles of its isoforms, AMPKα1 and AMPKα2, in AD, which may provide more precise targets for future drug development in AD.

Unraveling the Potential Underlying Mechanisms of Mild Behavioral Impairment: Focusing on Amyloid and Tau Pathology

The emergence of sustained neuropsychiatric symptoms (NPS) among non-demented individuals in later life, defined as mild behavioral impairment (MBI), is linked to a higher risk of cognitive decline. However, the underlying pathophysiological mechanisms remain largely unexplored. A growing body of evidence has shown that MBI is associated with alterations in structural and functional neuroimaging studies, higher genetic predisposition to clinical diagnosis of Alzheimer's disease (AD), as well as amyloid and tau pathology assessed in the blood, cerebrospinal fluid, positron-emission tomography (PET) imaging and neuropathological examination. These findings shed more light on the MBI-related potential neurobiological mechanisms, paving the way for the development of targeted pharmacological approaches. In this review, we aim to discuss the available clinical evidence on the role of amyloid and tau pathology in MBI and the potential underlying pathophysiological mechanisms. Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, disruption of neurotrophic factors, such as the brain-derived neurotrophic factor (BDNF), abnormal neuroinflammatory responses including the kynurenine pathway, dysregulation of transforming growth factor beta (TGF-β1), epigenetic alterations including micro-RNA (miR)-451a and miR-455-3p, synaptic dysfunction, imbalance in neurotransmitters including acetylcholine, dopamine, serotonin, gamma-aminobutyric acid (GABA) and norepinephrine, as well as altered locus coeruleus (LC) integrity are some of the potential mechanisms connecting MBI with amyloid and tau pathology. The elucidation of the underlying neurobiology of MBI would facilitate the design and efficacy of relative clinical trials, especially towards amyloid- or tau-related pathways. In addition, we provide insights for future research into our deeper understanding of its underlying pathophysiology of MBI, and discuss relative therapeutic implications.

Cognitive integrity in Non-Demented Individuals with Alzheimer's Neuropathology is associated with preservation and remodeling of dendritic spines

INTRODUCTION

Individuals referred to as Non-Demented with Alzheimer's Neuropathology (NDAN) exhibit cognitive resilience despite presenting Alzheimer's disease (AD) histopathological signs. Investigating the mechanisms behind this resilience may unveil crucial insights into AD resistance.

METHODS

DiI labeling technique was used to analyze dendritic spine morphology in control (CTRL), AD, and NDAN post mortem frontal cortex, particularly focusing on spine types near and far from amyloid beta (Aβ) plaques.

RESULTS

NDAN subjects displayed a higher spine density in regions distant from Aβ plaques versus AD patients. In distal areas from the plaques, NDAN individuals exhibited more immature spines, while AD patients had a prevalence of mature spines. Additionally, our examination of levels of Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1), a protein associated with synaptic plasticity and AD, showed significantly lower expression in AD versus NDAN and CTRL.

DISCUSSION

These results suggest that NDAN individuals undergo synaptic remodeling, potentially facilitated by Pin1, serving as a compensatory mechanism to preserve cognitive function despite AD pathology.

HIGHLIGHTS

Spine density is reduced near Aβ plaques compared to the distal area in CTRL, AD, and NDAN dendrites. NDAN shows higher spine density than AD in areas far from Aβ plaques. Far from Aβ plaques, NDAN has a higher density of immature spines, AD a higher density of mature spines. AD individuals show significantly lower levels of Pin1 compared to NDAN and CTRL.

Cornus officinalis Sieb. Et Zucc. attenuates Aβ25-35-induced mitochondrial damage and neuroinflammation in mice by modulating the ERK pathway

BACKGROUND

Cornus officinalis Sieb. Et Zucc. has the efficacy of tonifying the marrow and filling up the essence, breaking up the accumulation and opening up the orifices. Our research team found that CoS extracts were protective against Aβ25-35-induced memory impairment in mice. However, the pharmacodynamic components and mechanisms by which CoS improves AD have yet to be thoroughly explored and investigated.

PURPOSE

This study focused on exploring the bioactive components and pharmacodynamic mechanisms of CoS aqueous extract underlying mitochondrial damage and neuroinflammation to improve Aβ25-35-induced AD.

METHODS

AD mouse models were generated using Aβ25-35 brain injections. Different doses of CoS aqueous extract were orally administered to mice for 28 days. The cognitive function, neuronal and synaptic damage, mitochondrial damage (mitochondrial length, mitochondrial fusion fission-related protein expression), neuroglial activation, and immune inflammatory factor and ERK pathway-related protein levels of mice were assessed. The CoS aqueous extracts components were identified using UPLC-TQ/MS and screened for cellular activity. Midivi-1 (Drp1 inhibitor) or PD98059 (ERK inhibitor) was added to Aβ25-35-exposed PC12 cells to assess whether CoS and its active compounds mMorB and CorE regulate mitochondrial fission through ERK/Drp1. PC12-N9 cells were cocultured to investigate whether mMorB and CorE could regulate mitochondrial division through the ERK pathway to modulate neuroinflammation.

RESULTS

CoS improved exploration and memory in AD mice, reduced synaptic and mitochondrial damage in their hippocampus, and modulated disturbed mitochondrial dynamics. Moreover, CoS inhibited ERK pathway signaling and attenuated abnormal activation of glial cells and secondary immune inflammatory responses. Additionally, in vitro experiments revealed that CoS and its compounds 7β-O-methylmorroniside (mMorB) and Cornusdiridoid E (CorE) ameliorated mitochondrial injury caused by Aβ25-35 in PC12 cells through inhibition of the ERK/Drp1 pathway. Meanwhile, mMorB and CorE ameliorated cellular inflammation by inhibiting the Ras/ERK/CREB signaling pathway.

CONCLUSION

CoS aqueous extract ameliorates behavioral deficits and brain damage in Aβ25-35-induced AD mice by modulating the ERK pathway to attenuate mitochondrial damage and neuroinflammation, and the compounds mMorB and CorE are the therapeutically active ingredients.

Revisiting the focal role of endostatin and environmental factors in Alzheimer's disease

Alzheimer's disease (AD) is a condition initiated by the assimilation of β-amyloid plaques (Aβ) and tau tangles, leading to neurodegeneration. It involves frequently cognitive decline as well as memory impairment in patients. Efforts in therapeutic interventions are currently facing challenges in identifying targets within this scaffold that can significantly alter the clinical course for individuals with AD. Moreover, in AD, neurons release a protein called endostatin, which accumulates in Aβ plaques and enhances AD. This accumulation of Aβ in the triggers a cascade of events leading to synaptic dysfunction, neuroinflammation, and ultimately neuronal death. Environmental factors nowadays increase the risk of AD with prolonged exposure of heavy metals such as copper (Cu), lead (Pb), mercury (Hg), cadmium (Cd), and other pesticides. It has been observed that these factors can cause the aggregation of Aβ and tau which initiates the plaque formation and hence leads to enhanced pathogenesis of AD. This review summarizes the interlinking between heavy metals, environmental factors, pesticides, endostatin, and progression of AD has been deliberated with recent findings.

Evidence for a role of human blood-borne factors in mediating age-associated changes in molecular circadian rhythms

Aging is associated with a number of physiologic changes including perturbed circadian rhythms; however, mechanisms by which rhythms are altered remain unknown. To test the idea that circulating factors mediate age-dependent changes in peripheral rhythms, we compared the ability of human serum from young and old individuals to synchronize circadian rhythms in culture. We collected blood from apparently healthy young (age 25-30) and old (age 70-76) individuals at 14:00 and used the serum to synchronize cultured fibroblasts. We found that young and old sera are equally competent at initiating robust ~24h oscillations of a luciferase reporter driven by clock gene promoter. However, cyclic gene expression is affected, such that young and old sera promote cycling of different sets of genes. Genes that lose rhythmicity with old serum entrainment are associated with oxidative phosphorylation and Alzheimer's Disease as identified by STRING and IPA analyses. Conversely, the expression of cycling genes associated with cholesterol biosynthesis increased in the cells entrained with old serum. Genes involved in the cell cycle and transcription/translation remain rhythmic in both conditions. We did not observe a global difference in the distribution of phase between groups, but found that peak expression of several clock-controlled genes (PER3, NR1D1, NR1D2, CRY1, CRY2, and TEF) lagged in the cells synchronized ex vivo with old serum. Taken together, these findings demonstrate that age-dependent blood-borne factors affect circadian rhythms in peripheral cells and have the potential to impact health and disease via maintaining or disrupting rhythms respectively.

Diversity of amyloid beta peptide actions

Fibril formation by amyloidogenic proteins and peptides is considered the cause of a number of incurable diseases. One of the most known amyloid diseases is Alzheimer's disease (AD). Traditionally, amyloidogenic beta peptides Aβ40 and Aβ42 (Aβs) are considered as main causes of AD and the foremost targets in AD fight. The main efforts in pharmacology are aimed at reducing Aβs concentration to prevent their accumulation, aggregation, formation of senile plaques, neuronal death, and neurodegeneration. However, a number of publications have demonstrated certain beneficial physiological effects of Aβs. Simultaneously, it is indicated that the effects of Aβs turn into pathological due to the development of certain diseases in the body. The accumulation of C- and N-terminal truncated Aβs under diverse conditions is supposed to play a role in AD development. The significance of transformation of glutamate residue at positions 3 or 11 of Aβs catalyzed by glutaminyl cyclase making them more degradation resistant, hydrophobic, and prone to aggregation, as well as the participation of dipeptidyl peptidase IV in these transformations are discussed. The experimental data presented confirm the maintenance of physiological, nonaggregated state of Aβs by plant preparations. In conclusion, this review suggests that in the fight against AD, instead of removing Aβs, preference should be given to the treatment of common diseases. Glutaminyl cyclase and dipeptidyl peptidase IV can be considered as targets in AD treatment. Flavonoids and plant preparations that possess antiamyloidogenic propensity are proposed as beneficial neuroprotective, anticancer, and antidiabetic food additives.

Heat-Killed Lactococcus Lactis KC24 Ameliorates Scopolamine-Induced Memory Impairment in ICR Mice

Heat-killed Lactococcus lactis KC24 (H-KC24) has been examined for its neuroprotective effects in SH-SY5Y cells. We hypothesized that H-KC24 could alleviate memory impairment through the gut-brain axis. Scopolamine (1 mg/kg/day) was administered to ICR mice to induce memory impairment. Low- and high-dose H-KC24 cells (1 × 109 and 2 × 109 CFU/day, respectively) or donepezil (DO, 2 mg/kg) were administered for 14 days. H-KC24 treatment alleviated the deleterious scopolamine-induced memory effects on the recognition index and object recognition ability in the novel object recognition test and the Y-maze test. Changes in neurotransmitters and synaptic plasticity were confirmed by measuring acetylcholine, acetylcholinesterase, choline acetyltransferase, brain-derived neurotrophic factor, cyclic AMP response element-binding protein, and phosphorylated cyclic AMP response element-binding protein expression in brain tissues. In the H-KC24 and DO groups, β-secretase levels increased, whereas amyloid β levels decreased, demonstrating that H-KC24 can improve memory impairment caused by oxidative stress. This study demonstrated the positive effects of H-KC24 in a scopolamine-induced memory impairment mouse model.

Nanodisc Reconstitution and Characterization of Amyloid-β Precursor Protein C99

Amyloid precursor protein (APP) plays a pivotal role in the pathology of Alzheimer's disease (AD). Since the fragmentation of the membrane-bound APP that results in the production of amyloid-β peptides is the starting point for amyloid toxicity in AD, it is important to investigate the structure and dynamics of APP in a near-native lipid-bilayer environment. However, the reconstitution of APP into a stable and suitable membrane-mimicking lipid environment is a challenging task. In this study, the 99-residue C-terminal domain of APP is successfully reconstituted into polymer nanodiscs and characterized using size-exclusion chromatography, mass spectrometry, solution NMR, and magic-angle spinning solid-state NMR. In addition, the feasibility of using lipid-solubilizing polymers for isolating and characterizing APP in the native Escherichia. coli membrane environment is demonstrated.

Polymeric nanoparticles: A promising strategy for treatment of Alzheimer's disease

Alzheimer's disease (AD), is characterised by two major hallmarks: the formation of extracellular β-amyloid (Aβ) plaques and the hyperphosphorylation of tau protein, thus leading to the formation of neurofibrillary tangles. These hallmarks cause synaptic loss, neuronal damage, and the development of neuroinflammation and oxidative stress, which promote AD progression. Thus, the goal of treating AD is eliminating these hallmarks, to prevent AD progression and decrease symptoms. However, current available therapies provide symptomatic relief rather than treating the underlying cause of the disease, because the restrictive nature of the blood brain barrier (BBB) impedes the entry of drugs, thereby affecting drug efficacy and bioavailability. Researchers are focusing on developing new therapeutic approaches to bypass the BBB, for achieving site-specific drug delivery with the highest possible bioavailability and the lowest adverse effects. Recently explored therapeutic strategies include use of biologic agents such as monoclonal antibodies. Aducanumab, a strong candidate for treating AD, has been granted accelerated Food and Drug Administration approval; however, safety concerns may hinder its future use. Thus, nanotechnological approaches have led to a new era of AD treatment. Nanoparticles (NPs), because of their small particle size, can cross the BBB, thus enhancing drug pharmacokinetic properties and enabling targeted drug delivery. Polymeric NPs have been extensively studied, because of their simple production, biodegradability, biocompatibility, and unique architecture. These NPs provide a flexible vesicle that can be easily tailored to achieve desired physicochemical features. In this review, various types of polymer-based-NPs are discussed, highlighting the properties of fabricated NPs, which have multiple benefits in AD treatment, including anti-amyloid, antioxidant, and anti-inflammatory effects.

Roles of astrocytes and prions in Alzheimer's disease: insights from mathematical modeling

We present a mathematical model that explores the progression of Alzheimer's disease, with a particular focus on the involvement of disease-related proteins and astrocytes. Our model consists of a coupled system of differential equations that delineates the dynamics of amyloid beta plaques, amyloid beta protein, tau protein, and astrocytes. Amyloid beta plaques can be considered fibrils that depend on both the plaque size and time. We change our mathematical model to a temporal system by applying an integration operation with respect to the plaque size. Theoretical analysis including existence, uniqueness, positivity, and boundedness is performed in our model. We extend our mathematical model by adding two populations, namely prion protein and amyloid beta-prion complex. We characterize the system dynamics by locating biologically feasible steady states and their local stability analysis for both models. The characterization of the proposed model can help inform in advancing our understanding of the development of Alzheimer's disease as well as its complicated dynamics. We investigate the global stability analysis around the interior equilibrium point by constructing a suitable Lyapunov function. We validate our theoretical analysis with the aid of extensive numerical illustrations.

Potential Application of MicroRNAs and Some Other Molecular Biomarkers in Alzheimer's Disease

Alzheimer's disease (AD) is the world's most common neurodegenerative disease, expected to affect up to one-third of the elderly population in the near future. Among the major challenges in combating AD are the inability to reverse the damage caused by the disease, expensive diagnostic tools, and the lack of specific markers for the early detection of AD. This paper highlights promising research directions for molecular markers in AD diagnosis, including the diagnostic potential of microRNAs. The latest molecular methods for diagnosing AD are discussed, with particular emphasis on diagnostic techniques prior to the appearance of full AD symptoms and markers detectable in human body fluids. A collection of recent studies demonstrates the promising potential of molecular methods in AD diagnosis, using miRNAs as biomarkers. Up- or downregulation in neurodegenerative diseases may not only provide a new diagnostic tool but also serve as a marker for differentiating neurodegenerative diseases. However, further research in this direction is needed.

A comprehensive bibliometric analysis of global research on the role of acrolein in Alzheimer's disease pathogenesis: involvement of amyloid-beta

Background

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive and behavioral decline. Acrolein, an environmental pollutant and endogenous compound, is implicated in AD development. This research employs bibliometric analysis to assess current trends and key areas concerning acrolein-AD interaction.

Methods

The Web of Science was used to extensively review literature on acrolein and AD. Relevant data were systematically gathered and analyzed using VOSviewer, CiteSpace, and an online bibliometric tool.

Results

We identified 120 English publications in this specialized field across 19 journals. The Journal of Alzheimer's Disease was the most prominent. The primary contributors, both in terms of scientific output and influence, were the USA, the University of Kentucky, and Ramassamy C, representing countries/regions, institutions, and authors, respectively. In this field, the primary focus was on thoroughly studying acrolein, its roles, and its mechanisms in AD utilizing both in vivo and in vitro approaches. A significant portion of the research was based on proteomics, revealing complex molecular processes. The main focuses in the field were "oxidative stress," "lipid peroxidation," "amyloid-beta," and "cognitive impairment." Anticipated future research trajectories focus on the involvement of the internalization pathway, covering key areas such as synaptic dysfunction, metabolism, mechanisms, associations, neuroinflammation, inhibitors, tau phosphorylation, acrolein toxicity, brain infarction, antioxidants, chemistry, drug delivery, and dementia. Our analysis also supported our previous hypothesis that acrolein can interact with amyloid-beta to form a protein adduct leading to AD-like pathology and altering natural immune responses.

Conclusion

This study provides a broad and all-encompassing view of the topic, offering valuable insights and guidance to fellow researchers. These emerging directions underscore the continuous exploration of the complexities associated with AD. The analyses and findings aim to enhance our understanding of the intricate relationship between acrolein and AD for future research.

Clinical and Neuroimaging Predictors of Alzheimer's Dementia Conversion in Patients with Mild Cognitive Impairment Using Amyloid Positron Emission Tomography by Quantitative Analysis over 2 Years

Patients with mild cognitive impairment (MCI) have a relatively high risk of developing Alzheimer's dementia (AD), so early identification of the risk for AD conversion can lessen the socioeconomic burden. In this study, 18F-Florapronol, newly developed in Korea, was used for qualitative and quantitative analyses to assess amyloid positivity. We also investigated the clinical predictors of the progression from MCI to dementia over 2 years. From December 2019 to December 2022, 50 patients with MCI were recruited at a single center, and 34 patients were included finally. Based on visual analysis, 13 (38.2%) of 34 participants were amyloid-positive, and 12 (35.3%) were positive by quantitative analysis. Moreover, 6 of 34 participants (17.6%) converted to dementia after a 2-year follow-up (p = 0.173). Among the 15 participants who were positive for amyloid in the posterior cingulate region, 5 (33.3%) patients developed dementia (p = 0.066). The Clinical Dementia Rating-Sum of Boxes (CDR-SOB) at baseline was significantly associated with AD conversion in multivariate Cox regression analyses (p = 0.043). In conclusion, these results suggest that amyloid positivity in the posterior cingulate region and higher CDR-SOB scores at baseline can be useful predictors of AD conversion in patients with MCI.

Nanodisc reconstitution and characterization of amyloid-β precursor protein C99

Amyloid precursor protein (APP) plays a pivotal role in the pathology of Alzheimer's disease. Since the fragmentation of the membrane-bound APP that results in the production of amyloid-beta peptides is the starting point for amyloid toxicity in AD, it is important to investigate the structure and dynamics of APP in a near-native lipid-bilayer environment. However, the reconstitution of APP into a stable/suitable membrane-mimicking lipid environment is a challenging task. In this study, the 99-residue C-terminal domain of APP is successfully reconstituted into polymer nanodiscs and characterized using size-exclusion chromatography, mass spectrometry, solution NMR, and magic-angle spinning solid-state NMR. In addition, the feasibility of using lipid-solubilizing polymers for isolating and characterizing APP in native E. coli membrane environment is demonstrated.

SuanZaoRen decoction alleviates neuronal loss, synaptic damage and ferroptosis of AD via activating DJ-1/Nrf2 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

SuanZaoRen Decoction (SZRD), a famous herbal prescription, and has been widely proven to have positive therapeutic effects on insomnia, depression and Alzheimer's disease (AD). However, the anti-AD molecular mechanism of SZRD remains to be further investigated.

AIM OF THE STUDY

To elucidate the molecular mechanism of SZRD's improvement in AD's neuronal loss, synaptic damage and ferroptosis by regulating DJ-1/Nrf2 signaling pathway.

MATERIALS AND METHODS

LC-MS/MS was used to detect the active ingredients from SZRD. APP/PS1 mice was treated with SZRD and a ferroptosis inhibitor (Liproxstatin-1), respectively. Upon the completion of behavioral tests, Nissl staining, FJB staining, Golgi staining, immunofluorescence, immunohistochemistry, and transmission electron microscopy were preformed to evaluate the effects of SZRD on neuronal loss, synaptic damage, Aβ deposition. Iron staining, transmission electron microscopy, and iron assay kit was performed to estimate the effects of SZRD on ferroptosis. SOD kit, MDA kit, GSH kit, and GSH/GSSG kit were utilized to measure the oxidative stress levels in the hippocampus. The protein expression of TfR1, FTH1, FTL, FPN1, DJ-1, Nrf2, GPX4, SLC7A11, and ACSL4 were detected by Western blot.

RESULTS

A total of 16 active ingredients were identified from SZRD extract. SZRD SZRD significantly alleviated learning and memory impairment in APP/PS1 mice. SZRD improved the hippocampal neuronal loss and degenerated neurons in APP/PS1 mice via inhibiting the Aβ deposit. SZRD mitigated the hippocampal synaptic damage in APP/PS1 mice. SZRD inhibited iron accumulation, and alleviated the oxidative stress level in the hippocampus of APP/PS1 mice. Meanwhile, SZRD could up-regulate the protein expression level of FPN1, DJ-1, Nrf2, GPX4 and SLC7A11 in the hippocampus, and inhibit TfR1, FTH1, FTL, and ACSL4 protein expression.

CONCLUSION

SZRD alleviated neuronal loss, synaptic damage and ferroptosis in AD via activating DJ-1/Nrf2 signaling pathway.

Role of Serotonylation and SERT Posttranslational Modifications in Alzheimer's Disease Pathogenesis

The neurotransmitter serotonin (5-hydroxytryptamine, 5-HT) is implicated mainly in Alzheimer's disease (AD) and reported to be responsible for several processes and roles in the human body, such as regulating sleep, food intake, sexual behavior, anxiety, and drug abuse. It is synthesized from the amino acid tryptophan. Serotonin also functions as a signal between neurons to mature, survive, and differentiate. It plays a crucial role in neuronal plasticity, including cell migration and cell contact formation. Various psychiatric disorders, such as depression, schizophrenia, autism, and Alzheimer's disease, have been linked to an increase in serotonin-dependent signaling during the development of the nervous system. Recent studies have found 5-HT and other monoamines embedded in the nuclei of various cells, including immune cells, the peritoneal mast, and the adrenal medulla. Evidence suggests these monoamines to be involved in widespread intracellular regulation by posttranslational modifications (PTMs) of proteins. Serotonylation is the calcium-dependent process in which 5-HT forms a long-lasting covalent bond to small cytoplasmic G-proteins by endogenous transglutaminase 2 (TGM2). Serotonylation plays a role in various biological processes. The purpose of our article is to summarize historical developments and recent advances in serotonin research and serotonylation in depression, aging, AD, and other age-related neurological diseases. We also discussed several of the latest developments with Serotonin, including biological functions, pathophysiological implications and therapeutic strategies to treat patients with depression, dementia, and other age-related conditions.

Agmatine as a novel intervention for Alzheimer's disease: Pathological insights and cognitive benefits

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by progressive cognitive decline and a significant societal burden. Despite extensive research and efforts of the multidisciplinary scientific community, to date, there is no cure for this debilitating disease. Moreover, the existing pharmacotherapy for AD only provides symptomatic support and does not modify the course of the illness or halt the disease progression. This is a significant limitation as the underlying pathology of the disease continues to progress leading to the deterioration of cognitive functions over time. In this milieu, there is a growing need for the development of new and more efficacious treatments for AD. Agmatine, a naturally occurring molecule derived from L-arginine, has emerged as a potential therapeutic agent for AD. Besides this, agmatine has been shown to modulate amyloid beta (Aβ) production, aggregation, and clearance, key processes implicated in AD pathogenesis. It also exerts neuroprotective effects, modulates neurotransmitter systems, enhances synaptic plasticity, and stimulates neurogenesis. Furthermore, preclinical and clinical studies have provided evidence supporting the cognition-enhancing effects of agmatine in AD. Therefore, this review article explores the promising role of agmatine in AD pathology and cognitive function. However, several limitations and challenges exist, including the need for large-scale clinical trials, optimal dosing, and treatment duration. Future research should focus on mechanistic investigations, biomarker studies, and personalized medicine approaches to fully understand and optimize the therapeutic potential of agmatine. Augmenting the use of agmatine may offer a novel approach to address the unmet medical need in AD and provide cognitive enhancement and disease modification for individuals affected by this disease.

Data-driven Stochastic Model for Quantifying the Interplay Between Amyloid-beta and Calcium Levels in Alzheimer's Disease

The abnormal aggregation of extracellular amyloid-β ( A β ) in senile plaques resulting in calcium C a + 2 dyshomeostasis is one of the primary symptoms of Alzheimer's disease (AD). Significant research efforts have been devoted in the past to better understand the underlying molecular mechanisms driving A β deposition and C a + 2 dysregulation. Importantly, synaptic impairments, neuronal loss, and cognitive failure in AD patients are all related to the buildup of intraneuronal A β accumulation. Moreover, increasing evidence show a feed-forward loop between A β and C a + 2 levels, i.e. A β disrupts neuronal C a + 2 levels, which in turn affects the formation of A β . To better understand this interaction, we report a novel stochastic model where we analyze the positive feedback loop between A β and C a + 2 using ADNI data. A good therapeutic treatment plan for AD requires precise predictions. Stochastic models offer an appropriate framework for modelling AD since AD studies are observational in nature and involve regular patient visits. The etiology of AD may be described as a multi-state disease process using the approximate Bayesian computation method. So, utilizing ADNI data from 2-year visits for AD patients, we employ this method to investigate the interplay between A β and C a + 2 levels at various disease development phases. Incorporating the ADNI data in our physics-based Bayesian model, we discovered that a sufficiently large disruption in either A β metabolism or intracellular C a + 2 homeostasis causes the relative growth rate in both C a + 2 and A β , which corresponds to the development of AD. The imbalance of C a + 2 ions causes A β disorders by directly or indirectly affecting a variety of cellular and subcellular processes, and the altered homeostasis may worsen the abnormalities of C a + 2 ion transportation and deposition. This suggests that altering the C a + 2 balance or the balance between A β and C a + 2 by chelating them may be able to reduce disorders associated with AD and open up new research possibilities for AD therapy.

Monoclonal antibody therapy for Alzheimer's disease focusing on intracerebral targets

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Due to the complexity of the disorder and the presence of the blood-brain barrier (BBB), its drug discovery and development are facing enormous challenges, especially after several failures of monoclonal antibody (mAb) trials. Nevertheless, the Food and Drug Administration's approval of the mAb aducanumab has ushered in a new day. As we better understand the disease's pathogenesis and identify novel intracerebral therapeutic targets, antibody-based therapies have advanced over the past few years. The mAb drugs targeting β-amyloid or hyperphosphorylated tau protein are the focus of the current research. Massive neuronal loss and glial cell-mediated inflammation are also the vital pathological hallmarks of AD, signaling a new direction for research on mAb drugs. We have elucidated the mechanisms by which AD-specific mAbs cross the BBB to bind to targets. In order to investigate therapeutic approaches to treat AD, this review focuses on the promising mAbs targeting intracerebral dysfunction and related strategies to cross the BBB.

DDQ anti-aging properties expressed with improved mitophagy in mutant tau HT22 neuronal cells

The purpose of our study is to develop age-related phosphorylated tau (p-tau) inhibitors, for Alzheimer's disease (AD). There are wide-ranging therapeutic molecules available in the market and tested for age-related p-tau inhibition to enhance phosphatase activity and microtubule stability in AD neurons. Until now there are no such small molecules claimed to show promising results to delay the disease process of AD. However, a recently developed molecule, DDQ, has been shown to reduce abnormal protein-protein interactions and protect neurons from mutant protein-induced toxicities in the disease process. In addition, DDQ reduced age- and Aβ-induced oxidative stress, mitochondrial dysfunction, and synaptic toxicity. To date, there are no published reports on the p-tau interaction of DDQ and Sirt3 upregulation with CREB-mediated mitophagy activation in AD neurons. In the current study, HT22 cells were transfected with mutant Tau (mTau) cDNA and treated with the novel molecule DDQ. Cell survival, immunoblotting, and immunofluorescence analysis were conducted to assess cell viability and synaptic and mitophagy proteins in treated and untreated cell groups. As expected, we found cell survival was decreased in mTau-HT22 cells when compared with control HT22 cells. However, cell survival was increased in DDQ-treated mTau-HT22 cells when compared with mTau HT22 cells. P-tau and total tau proteins were significantly reduced in DDQ-treated mTau-HT22 cells, and MAP2 levels were increased. Anti-aging proteins like Sirt3, and CREB levels were increased in DDQ-treated HT22 cells and also in mTau-HT22 cells treated DDQ. Mitophagy proteins were decreased in mTau-HT22 cells and these were increased in DDQ-treated mTau-HT22 cells. These observations strongly suggest that DDQ has anti-p-tau and anti-aging properties, via Sirt3 overexpression and increased mitophagy proteins. Our study findings may have implications for healthy aging to the development of p-tau targeted therapeutics in AD and tauopathies.