Multi-omics delineate growth factor network underlying exercise effects in an Alzheimer's mouse model

INTRODUCTION

Physical exercise is a primary defense against age-related cognitive decline and Alzheimer's disease (AD).

METHODS

We conducted single-nucleus transcriptomic and chromatin accessibility analyses (snRNA-seq and snATAC-seq) on the hippocampus of mice carrying mutations in the amyloid precursor protein gene (APPNL-G-F) following prolonged voluntary wheel-running exercise.

RESULTS

Exercise mitigates amyloid-induced changes in transcriptome and chromatin accessibility through cell type-specific regulatory networks converging on growth factor signaling, particularly the epidermal growth factor receptor (EGFR) signaling. The beneficial effects of exercise on neurocognition can be blocked by pharmacological inhibition of EGFR and its downstream PI3K signaling. Exercise leads to elevated levels of heparin-binding EGF (HB-EGF), and intranasal administration of HB-EGF enhances memory function in sedentary APPNL-G-F mice.

DISCUSSION

These findings offer a panoramic delineation of cell type-specific hippocampal transcriptional networks activated by exercise and suggest EGFR signaling as a druggable contributor to exercise-induced memory enhancement to combat AD-related cognitive decline.

HIGHLIGHTS

snRNA-seq and snATAC-seq analysis of APPNL-G-F mice after prolonged wheel-running. Exercise counteracts amyloid-induced transcriptomic and accessibility changes. Networks converge on the activation of EGFR and insulin signaling. Pharmacological inhibition of EGFR and PI3K blocked cognitive benefits of exercise. Intranasal HB-EGF administration enhances memory in sedentary APPNL-G-F mice.

Sociodemographic modifiers of effects of statin initiation on dementia incidence: An emulated trial design in a large health care member population with 10+ years of follow-up

INTRODUCTION

Mixed evidence on how statin use affects risk of Alzheimer's disease and related dementias (ADRD) may reflect heterogeneity across sociodemographic factors. Few studies have sufficient power to evaluate effect modifiers.

METHODS

Kaiser Permanente Northern California (KPNC) members (n = 705,061; n = 202,937 with sociodemographic surveys) who initiated statins from 2001 to 2010 were matched on age and low-density lipoprotein cholesterol (LDL-C) with non-initiators and followed through 2020 for incident ADRD. Inverse probability-weighted Cox proportional hazards models were used to evaluate effect modification by age, gender, race/ethnicity, education, marital status, income, and immigrant generation.

RESULTS

Statin initiation (vs non-initiation) was not associated with ADRD incidence in any of the 32 subgroups (p > .05). Hazard ratios ranged from 0.964 (95% CI: 0.923 to 1.006) among Asian-identified participants to 1.122 (95% CI: 0.995 to 1.265) in the highest income category.

DISCUSSION

Sociodemographic heterogeneity appears to have little to no influence on the relationship between statin initiation and dementia.

HIGHLIGHTS

The study includes a large and diverse cohort from Kaiser Permanente (N = 705,061). An emulated trial design of statin initiation on dementia incidence was used. Effect modification by sociodemographic factors was assessed. There were no significant Alzheimer's disease and related dementias (ADRD) risk differences in 32 sociodemographic subgroups (p > 0.05).

Glial 'omics in ischemia: Acute stroke and chronic cerebral small vessel disease

Vascular injury and pathologies underlie common diseases including ischemic stroke and cerebral small vessel disease (CSVD). Prior work has identified a key role for glial cells, including microglia, in the multifaceted and temporally evolving neuroimmune response to both stroke and CSVD. Transcriptional profiling has led to important advances including identification of distinct gene expression signatures in ischemia-exposed, flow cytometrically sorted microglia and more recently single cell RNA sequencing-identified microglial subpopulations or clusters. There is a reassuring degree of overlap in the results from these two distinct methodologies with both identifying a proliferative and a separate type I interferon responsive microglial element. Similar patterns were later seen using multimodal and spatial transcriptomal profiling in ischemia-exposed microglia and astrocytes. Methodological advances including enrichment of specific neuroanatomic/functional regions (such as the neurovascular unit) prior to single cell RNA sequencing has led to identification of novel cellular subtypes and generation of new credible hypotheses as to cellular function based on the enhanced cell sub-type specific gene expression patterns. A ribosomal tagging strategy focusing on the cellular translatome analyses carried out in the acute phases post stroke has revealed distinct inflammation-regulating roles for microglia and astrocytes in this setting. Early spatial transcriptomics experiments using cerebral ischemia models have identified regionally distinct microglial cell clusters in ischemic core versus penumbra. There is great potential for combination of these methods for multi-omics approaches to further elucidate glial responses in the context of both acute ischemic stroke and chronic CSVD.

QSP Modeling Shows Pathological Synergism Between Insulin Resistance and Amyloid-Beta Exposure in Upregulating VCAM1 Expression at the BBB Endothelium

Type 2 diabetes mellitus (T2DM), characterized by insulin resistance, is closely associated with Alzheimer's disease (AD). Cerebrovascular dysfunction is manifested in both T2DM and AD, and is often considered as a pathological link between the two diseases. Insulin signaling regulates critical functions of the blood-brain barrier (BBB), and endothelial insulin resistance could lead to BBB dysfunction, aggravating AD pathology. However, insulin signaling is intrinsically dynamic and involves interactions among numerous molecular mediators. Hence, a mechanistic systems biology model is needed to understand how insulin regulates BBB physiology and the consequences of its impairment in T2DM and AD. In this study, we investigated the pharmacodynamic effect of insulin on the expression of vascular cell adhesion molecule 1 (VCAM1), a marker of cerebrovascular inflammation. Intriguingly, normal insulin concentrations selectively activated the PI3K-AKT pathway, leading to decreased VCAM1 expression. However, exposure to supraphysiological insulin levels, which is present in insulin resistance, activated both PI3K-AKT and MEK-ERK pathways, and increased VCAM1 expression. We developed a mathematical model that adequately described the dynamics of various insulin signaling nodes and VCAM1 expression. Further, the model was integrated with in vitro proteomics and transcriptomics data from AD patients to simulate VCAM1 expression under pathological conditions. This approach allowed us to establish a quantitative systems pharmacology framework to investigate BBB dysfunction in AD and metabolic syndrome, thereby offering opportunities to identify specific disruptions in molecular networks that will enable us to identify novel therapeutic targets.

Exercise alleviates cognitive decline of natural aging rats by upregulating Notch-mediated autophagy signaling

Notch signaling, a classical signaling pathway of neurogenesis, is downregulated during the aging and age-related neurodegenerative diseases. Exercise has been proposed as an effective lifestyle intervention for delaying cognitive decline. However, it remains unclear whether exercise intervention could alleviate cognitive decline by modulating neurogenesis in naturally aging rats. In this study, 21-month-old natural aging rats were used to study brain aging. The natural aging rats underwent different forms of exercise training (aerobic exercise or strength training or comprehensive exercise with aerobic exercise and strength training) for 12 consecutive weeks. The cognitive function of natural aging rats was determined by Morris Water Maze. Notch signaling, autophagy-related proteins and hippocampal neurogenesis were examined by immunofluorescence, qRT-PCR and Western blot. Results showed that natural aging rats exhibited cognitive decline, accumulation of AD pathological proteins (APP and Aβ), and decreased neurogenesis (decreased DCX, Ki67 and GFAP), compared with the young control rats. Moreover, a significant decline in Notch signaling and autophagy was found in the hippocampus of natural aging rats. However, different forms of exercise upregulated Notch signaling and its downstream target genes, as well as autophagy-related proteins, including LC3, Beclin1, and p62. In summary, our data suggest that different forms of exercise can mitigate brain aging by upregulating Notch signaling and autophagy, thereby increasing hippocampal neurogenesis and improves spatial learning and memory abilities.

Reduced Functional Connectivity in Nucleus Accumbens Subregions Associates With Cognitive Changes in Alzheimer's Disease

BACKGROUND AND PURPOSE

The nucleus accumbens (NAc), an important component of the reward circuit, is believed to play an indispensable role in Alzheimer's disease (AD). This study aimed to explore alterations in the functional connectivity (FC) of NAc subregions in AD patients and to explore their associations with neuropsychological profiles.

METHODS

Total 45 AD patients and 41 healthy controls (HCs) were recruited for this study. Four subregions of the NAc were used as regions of interest for whole-brain FC analysis. Correlation analyses were conducted to explore the relationships between the changed FC of brain regions with significant differences and neuropsychological profiles.

RESULTS

Compared with HCs, decreased FC was observed between NAc subregions and regions of the orbitofrontal cortex (OFC), precuneus (PCUN), insula (INS), cerebellum 8, and putamen in AD patients (Gaussian random field [GRF] corrected, voxel-level p < 0.001, cluster-level p < 0.05). Furthermore, the FC between the left core and left PCUN was correlated with the score of the auditory verbal learning test immediate recall task in AD patients (r = 0.441, p = 0.003, Bonferroni corrected).

CONCLUSION

Disruptions in connectivity between the NAc subregions and important cognitive-related areas may be related to the cognitive deficits observed in AD patients, especially episodic memory function.

Hippocampal neurogenesis in adult primates: a systematic review

It had long been considered that no new neurons are generated in the primate brain beyond birth, but recent studies have indicated that neurogenesis persists in various locations throughout the lifespan. The dentate gyrus of the hippocampus is of particular interest due to the postulated role played by neurogenesis in memory. However, studies investigating the presence of adult hippocampal neurogenesis (AHN) have reported contradictory findings, and no systematic review of the evidence has been conducted to date. We searched MEDLINE, Embase and PsycINFO on 27th June 2023 for studies on hippocampal neurogenesis in adult primates, excluding review papers. Screening, quality assessment and data extraction was done by independent co-raters. We synthesised evidence from 112 relevant papers. We found robust evidence, primarily supported by immunohistochemical examination of tissue samples and neuroimaging, for newly generated neurons, first detected in the subgranular zone of the dentate gyrus, that mature over time and migrate to the granule cell layer, where they become functionally integrated with surrounding neuronal networks. AHN has been repeatedly observed in both humans and other primates and gradually diminishes with age. Transient increases in AHN are observed following acute insults such as stroke and epileptic seizures, and following electroconvulsive therapy, and AHN is diminished in neurodegenerative conditions. Markers of AHN correlate positively with measures of learning and short-term memory, but associations with antidepressant use and mood states are weaker. Heterogeneous outcome measures limited quantitative syntheses. Further research should better characterise the neuropsychological function of neurogenesis in healthy subjects.

Blood-brain barrier water permeability across the adult lifespan: A multi-echo ASL study

An emerging biomarker of blood-brain barrier (BBB) permeability is the time of exchange (Tex) of water from the blood to tissue, as measured by multi-echo arterial spin labeling (ASL) MRI. This new non-invasive sequence, already tested in mice, has recently been adapted to humans and optimized for clinical scanning time. In this study, we studied the normal variability of Tex over age and sex, which needs to be established as a reference for studying changes in neurological disease. We evaluated Tex, cerebral blood flow (CBF) and arterial transit time (ATT) in 209 healthy adults between 26 and 87 years, over age and sex, using general linear models in gray matter, white matter, and regionally in cerebral lobes. After QC, 194 participants were included in the main analysis, and the results demonstrated that both gray matter (GM) and white matter (WM) BBB permeability was higher with higher age (Tex lower by 0.47 ms per year in GM [p < 0.05], and by 0.49 ms in WM, for females; no significant for males), with the largest Tex difference in the frontal lobes (0.64 ms decrease per year, p = 0.011, population average). CBF was lower with higher age in the GM (-0.71 mL/min/100g per year, p < 0.001, for females; -0.31 mL/min/100g per year, p < 0.05, for males). When correcting Tex models for CBF and ATT, effect of age on Tex disappears in the GM, but not in the WM (β=-0.28, p = 0.08). The CBF findings of this study are in line with previous studies, demonstrating the validity of the new sequence. The BBB water permeability variation over age and sex described in this study provides a reference for future BBB research.

Age-Related Neurodegenerative Diseases: A Stem Cell's Perspective

Neurodegenerative diseases encompass a number of very heterogeneous disorders, primarily characterized by neuronal loss and a concomitant decline in neurological function. Examples of this type of clinical condition are Alzheimer's Disease, Parkinson's Disease, Huntington's Disease and Amyotrophic Lateral Sclerosis. Age has been identified as a major risk in the etiology of these disorders, which explains their increased incidence in developed countries. Unfortunately, despite continued and intensive efforts, no cure has yet been found for any of these diseases; reliable markers that allow for an early diagnosis of the disease and the identification of key molecular events leading to disease onset and progression are lacking. Altered adult neurogenesis appears to precede the appearance of severe symptoms. Given the scarcity of human samples and the considerable differences with model species, increasingly complex human stem-cell-based models are being developed. These are shedding light on the molecular alterations that contribute to disease development, facilitating the identification of new clinical targets and providing a screening platform for the testing of candidate drugs. Moreover, the secretome and other promising features of these cell types are being explored, to use them as replacement cells of high plasticity or as co-adjuvant therapy in combinatorial treatments.

Engrams across diseases: Different pathologies - unifying mechanisms?

Memories are our reservoir of knowledge and thus, are crucial for guiding decisions and defining our self. The physical correlate of a memory in the brain is termed an engram and since decades helps researchers to elucidate the intricate nature of our imprinted experiences and knowledge. Given the importance that memories have for our lives, their impairment can present a tremendous burden. In this review we aim to discuss engram malfunctioning across diseases, covering dementia-associated pathologies, epilepsy, chronic pain and psychiatric disorders. Current neuroscientific tools allow to witness the emergence and fate of engram cells and enable their manipulation. We further suggest that specific mechanisms of mnemonic malfunction can be derived from engram cell readouts. While depicting the way diseases act on the mnemonic component - specifically, on the cellular engram - we emphasize a differentiation between forms of amnesia and hypermnesia. Finally, we highlight commonalities and distinctions of engram impairments on the cellular level across diseases independent of their pathogenic origins and discuss prospective therapeutic measures.

Behavioral and pathological characteristics of 5xFAD female mice in the early stage

Alzheimer's disease (AD) is a central nervous system degenerative disease with insidious onset and gradual development caused by selective and progressive loss of neurons. The 5xFAD mouse is a relatively mature disease model of AD. However, the behavioral research on 5xFAD female mouse is more focused on the changes of late memory function, and the exploration of its early behavioral and pathological changes is still incomplete. This research aims to explore the changes in memory function, emotional function (including anxiety and depression), motor ability, amyloid plaques, glial cell response and neurogenesis in the hippocampus of female 5xFAD mice in the early stage, laying a foundation for a comprehensive exploration of the disease mechanism of AD. The results of this study found that early 4-month-old female 5xFAD mice mainly showed a decline in memory function without other dysfunction. Accompanied by a large amount of amyloid protein plaques deposited in the hippocampus, it induced the response of microglia and astrocytes, and neurogenesis decreased significantly with age, especially in early female 5xFAD mice, which resulted in a decrease in the number of new neurons. This may be an important reason for the decline in memory function of female 5xFAD mice in the early stage.

Dual recombinase-mediated intersectional genetics defines the functional heterogeneity of neural stem cells in adult hippocampus

The Cre-lox site-specific recombinase system is one of the most powerful and versatile technology platforms for studying neural stem cells (NSCs) in adult brain, which is now challenged due to the complex and dynamic nature of in vivo gene expression. In this study, we develop an inducible dual recombinase-mediated intersectional genetics by combining Dre-rox and Cre-lox recombination technologies to specifically target two subpopulations of NSCs (α- and β-NSCs). By visiting their cell lineage and functionality, we find that α- and β-NSCs display distinct self-renewal and differentiation potential, as well as differential responses to external stimuli. Notably, in contrast to α-NSCs, the number of β-NSCs is not affected in aged mice and an APP/PS1 mouse model of Alzeimer's disease. Single cell transcriptome analysis reveals divergent molecular signatures between type α- and β-NSCs and identifies PRMT1 as an important regulatory element to differentially regulate the neurogenic potential of α- and β-NSCs. Inhibition of PRMT1 specifically enhances the neurogenic capacity of β-NSCs and promotes the cognition functions in aged mice. Importantly, PRMT1 inhibition combined with increased BDNF levels pharmacologically ameliorates the cognitive impairments in APP/PS1 mice. Together, our study suggests that understanding the functional heterogeneity of NSCs might pave the way for harnessing the specific subpopulation of NSCs to treat brain disorders.

Sustaining Brain Youth by Neural Stem Cells: Physiological and Therapeutic Perspectives

In the last two decades, stem cells (SCs) have attracted considerable interest for their research value and therapeutic potential in many fields, namely in neuroscience. On the other hand, the discovery of adult neurogenesis, the process by which new neurons are generated in the adult brain, challenged the traditional view that the brain is a static structure after development. The recent findings showing that adult neurogenesis has a significant role in brain plasticity, learning and memory, and emotional behavior, together with the fact that it is strongly dependent on several external and internal factors, have sparked more interest in this area. The mechanisms of adult neural stem cell (NSC) regulation, the physiological role of NSC-mediated neuroplasticity throughout life, and the most recent NSC-based therapeutic applications will be concisely reviewed. Noteworthy, due to their multipotency, self-renewal potential, and ability to secrete growth and immunomodulatory factors, NSCs have been mainly suggested for (1) transplantation, (2) neurotoxicology tests, and (3) drug screening approaches. The clinical trials of NSC-based therapy for different neurologic conditions are, nonetheless, mostly in the early phases and have not yet demonstrated conclusive efficacy or safety. Here, we provide an outlook of the major challenges and limitations, as well as some promising directions that could help to move toward stem cell widespread use in the treatment and prevention of several neurological disorders.

Sex-Specific Adaptations in Alzheimer's Disease and Ischemic Stroke: A Longitudinal Study in Male and Female APPswe/PS1dE9 Mice

The long-term impact of stroke on Alzheimer's disease (AD) progression, particularly regarding sex-specific differences, remains unknown. Using a longitudinal study design, we investigated transient middle cerebral artery occlusion in 3.5-month-old APPswe/PS1dE9 (APP/PS1) and wild-type mice. In vivo, we assessed behavior, cerebral blood flow (CBF), and structural integrity by neuroimaging, as well as post-mortem myelin integrity (polarized light imaging, PLI), neuroinflammation, and amyloid beta (Aβ) deposition. APP/PS1 mice exhibited cognitive decline, white matter degeneration (reduced fractional anisotropy (FA) via diffusion tensor imaging (DTI)), and decreased myelin density via PLI. Despite early hypertension, APP/PS1 mice showed only sporadic hypoperfusion. Cortical thickening and hippocampal hypertrophy likely resulted from Aβ accumulation and neuroinflammation. Stroke-operated mice retained cognition despite cortical thinning and hippocampal atrophy due to cerebrovascular adaptation, including increased CBF in the hippocampus and thalamus. Stroke did not worsen AD pathology, nor did AD exacerbate stroke outcomes. Sex differences were found: female APP/PS1 mice had more severe Aβ deposition, hyperactivity, lower body weight, and reduced CBF but less neuroinflammation, suggesting potential neuroprotection. These findings highlight white matter degeneration and Aβ pathology as key drivers of cognitive decline in AD, with stroke-related deficits mitigated by (cerebro)vascular adaptation. Sex-specific therapies are crucial for AD and stroke.

Gut microbiota: A new window for the prevention and treatment of neuropsychiatric disease

Under normal physiological conditions, gut microbiota and host mutually coexist. They play key roles in maintaining intestinal barrier integrity, absorption, and metabolism, as well as promoting the development of the central nervous system (CNS) and emotional regulation. The dysregulation of gut microbiota homeostasis has attracted significant research interest, specifically in its impact on neurological and psychiatric disorders. Recent studies have highlighted the important role of the gut- brain axis in conditions including Alzheimer's Disease (AD), Parkinson's Disease (PD), and depression. This review aims to elucidate the regulatory mechanisms by which gut microbiota affect the progression of CNS disorders via the gut-brain axis. Additionally, we discuss the current research landscape, identify gaps, and propose future directions for microbial interventions against these diseases. Finally, we provide a theoretical reference for clinical treatment strategies and drug development for AD, PD, and depression.

Optineurin-facilitated axonal mitochondria delivery promotes neuroprotection and axon regeneration

Optineurin (OPTN) mutations are linked to amyotrophic lateral sclerosis (ALS) and normal tension glaucoma (NTG), but a relevant animal model is lacking, and the molecular mechanisms underlying neurodegeneration are unknown. We find that OPTN C-terminus truncation (OPTN∆C) causes late-onset neurodegeneration of retinal ganglion cells (RGCs), optic nerve (ON), and spinal cord motor neurons, preceded by a decrease of axonal mitochondria in mice. We discover that OPTN directly interacts with both microtubules and the mitochondrial transport complex TRAK1/KIF5B, stabilizing them for proper anterograde axonal mitochondrial transport, in a C-terminus dependent manner. Furthermore, overexpressing OPTN/TRAK1/KIF5B prevents not only OPTN truncation-induced, but also ocular hypertension-induced neurodegeneration, and promotes robust ON regeneration. Therefore, in addition to generating animal models for NTG and ALS, our results establish OPTN as a facilitator of the microtubule-dependent mitochondrial transport necessary for adequate axonal mitochondria delivery, and its loss as the likely molecular mechanism of neurodegeneration.

Inhibition of repulsive guidance molecule A ameliorates diabetes-induced cognitive decline and hippocampal neurogenesis impairment in mice

Although diabetes mellitus is strongly associated with dementia, the mechanism underlying diabetes-induced cognitive dysfunction has not been clarified. Here, we demonstrate the vital role of repulsive guidance molecule A (RGMa) in the regulation of adult hippocampal neurogenesis and cognitive impairment under diabetic conditions. In type 2 diabetic db/db mice and streptozotocin-mediated type 1 diabetic mice, RGMa is upregulated in the granular cell layer of the dentate gyrus. Additionally, both neural stem cells (NSCs) and immature neurons express its receptor, neogenin. In vitro experiments revealed that high glucose-conditioned hippocampal neurons inhibited the differentiation of NSCs, and the application of an anti-RGMa antibody restored it. The treatment with an anti-RGMa antibody ameliorated diabetes-induced cognitive decline and impairment of hippocampal neurogenesis. These findings suggest that the RGMa negatively regulates hippocampal neurogenesis and is involved in diabetes mellitus-induced cognitive decline.

Caveolin and oxidative stress in cardiac pathology

Caveolins interact with signaling molecules within caveolae and subcellular membranes. Dysregulation of caveolin function and protein abundance contributes to cardiac pathophysiological processes, driving the development and progression of heart disease. Reactive oxygen species (ROS) play a critical role in maintaining cellular homeostasis and are key contributors to the pathophysiological mechanisms of cardiovascular disorders. Caveolins have been shown to modulate oxidative stress and regulate redox homeostasis. However, the specific roles of caveolins, particularly caveolin-1 and caveolin-3, in regulating ROS production during cardiac pathology remain unclear. This mini-review article highlights the correlation between caveolins and oxidative stress in maintaining cardiovascular health and modulating cardiac diseases, specifically in myocardial ischemia, heart failure, diabetes-induced metabolic cardiomyopathy, and septic cardiomyopathy. A deeper understanding of caveolin-mediated mechanisms may pave the way for innovative therapeutic approaches to treat cardiovascular diseases.

Newer Therapeutic Approaches in Treating Alzheimer's Disease: A Comprehensive Review

Alzheimer's disease (AD) is an aging-related irreversible neurodegenerative disease affecting mostly the elderly population. The main pathological features of AD are the extracellular Aβ plaques generated by APP cleavage through the amyloidogenic pathway, the intracellular neurofibrillary tangles (NFT) resulting from the hyperphosphorylated tau proteins, and cholinergic neurodegeneration. However, the actual causes of AD are unknown, but several studies suggest hereditary mutations in PSEN1 and -2, APOE4, APP, and the TAU genes are the major perpetrators. In order to understand the etiology and pathogenesis of AD, various hypotheses are proposed. These include the following hypotheses: amyloid accumulation, tauopathy, inflammation, oxidative stress, mitochondrial dysfunction, glutamate/excitotoxicity, cholinergic deficiency, and gut dysbiosis. Currently approved therapeutic interventions are donepezil, galantamine, and rivastigmine, which are cholinesterase inhibitors (ChEIs), and memantine, which is an N-methyl-d-aspartate (NMDA) antagonist. These treatment strategies focus on only symptomatic management of AD by attenuating symptoms but not regeneration of neurons or clearance of Aβ plaques and hyperphosphorylated Tau. This review focuses on the pathophysiology, novel therapeutic targets, and disease-altering treatments such as α-secretase modulators, active immunotherapy, passive immunotherapy, natural antioxidant products, nanomaterials, antiamyloid therapy, tau aggregation inhibitors, transplantation of fecal microbiota or stem cells, and microtubule stabilizers that are in clinical trials or still under investigation.

Spatiotemporal analysis of gene expression in the human dentate gyrus reveals age-associated changes in cellular maturation and neuroinflammation

The dentate gyrus of the hippocampus is important for many cognitive functions, including learning, memory, and mood. Here, we present transcriptome-wide spatial gene expression maps of the human dentate gyrus and investigate age-associated changes across the lifespan. Genes associated with neurogenesis and the extracellular matrix are enriched in infants and decline throughout development and maturation. Following infancy, inhibitory neuron markers increase, and cellular proliferation markers decrease. We also identify spatio-molecular signatures that support existing evidence for protracted maturation of granule cells during adulthood and age-associated increases in neuroinflammation-related gene expression. Our findings support the notion that the hippocampal neurogenic niche undergoes major changes following infancy and identify molecular regulators of brain aging in glial- and neuropil-enriched tissue.

Comparative molecular landscapes of immature neurons in the mammalian dentate gyrus across species reveal special features in humans

Immature dentate granule cells (imGCs) arising from adult hippocampal neurogenesis contribute to plasticity, learning and memory, but their evolutionary changes across species and specialized features in humans remain poorly understood. Here we performed machine learning-augmented analysis of published single-cell RNA-sequencing datasets and identified macaque imGCs with transcriptome-wide immature neuronal characteristics. Our cross-species comparisons among humans, monkeys, pigs, and mice showed few shared (such as DPYSL5), but mostly species-specific gene expression in imGCs that converged onto common biological processes regulating neuronal development. We further identified human-specific transcriptomic features of imGCs and demonstrated functional roles of human imGC-enriched expression of a family of proton-transporting vacuolar-type ATPase subtypes in development of imGCs derived from human pluripotent stem cells. Our study reveals divergent gene expression patterns but convergent biological processes in the molecular characteristics of imGCs across species, highlighting the importance of conducting independent molecular and functional analyses for adult neurogenesis in different species.

Models developed to explain the effects of stress on brain and behavior

There is an integral relationship between stress, brain function and behavior. Over the year's extensive research has led to the development of various models to explain the intricate intersection between brain and stress. This chapter delves into some of the theoretical frameworks that explains the neurobiological and behavioral responses to stress using key models of stress such as the allostatic load model, which is the most common model that describes how chronic stress affect brain structure and function resulting in long-term changes in regions such as the hippocampus, amygdala, and prefrontal cortex which phenotypically express as cognitive impairments, emotional dysfunction seen in various forms of neurological disorder. The neuro-endocrine model, follows the glucocorticoid cascade hypothesis, that associates prolonged stress exposure to hippocampal damage and cognitive decline via alteration in the hypothalamic-pituitary-adrenal (HPA) axis and the overproduction of stress hormones like cortisol which can induce hippocampal atrophy, impair learning and memory, and promote depressive-like behaviors. The neurobiological stress model addresses the role of the hypothalamic-pituitary-adrenal (HPA) axis and stress-related neurotransmitters in shaping behavioral responses, emphasizing alterations in neuroplasticity and synaptic function. These models demonstrate how chronic stress can alter neural plasticity, neurotransmitter systems, and synaptic connectivity, affecting behavior and cognitive function. Hence by integrating molecular, neurobiological, and behavioral perspectives, these models offer a comprehensive understanding of how stress alters brain activity and behavior. The chapter further showcase how these models direct the development of medical interventions, shedding light on potential therapies that target the underlying molecular mechanisms of stress-induced brain changes.

Functional Proteins/Peptides Targeting to Clear Amyloid-β for Alzheimer's Disease Therapy

Alzheimer's disease (AD) is a significant neurodegenerative disorder primarily affecting individuals over the age of 65. It is characterized by impairments in memory, thinking, analytical judgment, visuospatial recognition, and mood. In recent years, the development of protein and peptide drugs targeting amyloid-beta (Aβ) has gained momentum, with several therapies entering clinical trials and even receiving marketing approval. Novel functional protein and peptide drugs, as the first-generation immunotherapeutic agents for neurodegenerative diseases, have pioneered cellular immunotherapy for AD. However, the currently available drugs are associated with toxicity issues, which can lead to serious complications such as cerebral hemorrhage or edema. Consequently, this study examines the potential for a new generation of Aβ-targeting drugs to mitigate the side effects of existing treatments and offers innovative perspectives for the advancement of therapies for AD.

Unveiling synergies: Integrating TCM herbal medicine and acupuncture with conventional approaches in stroke management

This review explores the mechanisms and treatment strategies of ischemic stroke, a leading cause of morbidity and mortality worldwide. Ischemic stroke results from the obstruction of blood flow to the brain, leading to significant neurological impairment. The paper categorizes ischemic stroke into subtypes based on etiology, including cardioembolism and large artery atherosclerosis, and discusses the challenges of current therapeutic approaches. Conventional treatments like tissue plasminogen activator (tPA) and surgical interventions are limited by narrow windows and potential complications. The review highlights the promise of acupuncture, which offers neuroprotective benefits by promoting cerebral ischemic tolerance and neural regeneration. Integrating acupuncture with conventional treatments may enhance patient outcomes. Emphasis is placed on understanding the pathophysiology to develop targeted therapies that mitigate neuronal damage and enhance recovery.

How Can Early Stress Influence Later Alzheimer's Disease Risk? Possible Mediators and Underlying Mechanisms

Alzheimer's disease (AD) is a progressive, age-related neurodegenerative disorder to which genetic mutations and risk factors contribute. Evidence is increasing that environmental and lifestyle-related factors, such as exercise, nutrition, education, and exposure to (early-life) stress modify the onset, incidence, and progression of AD. Here, we discuss recent preclinical findings on putative substrates that can explain or contribute to the effects of stress early in life on the risk of developing AD. We focus in particular on stress hormones, neural networks, synapses, mitochondria, nutrient and lipid metabolism, adult neurogenesis, engram cell ensembles, and neuroinflammation. We discuss the idea that stress exposure early in life can alter these processes, either combined or in isolation, thereby reducing the capacity of the brain to resist deleterious consequences of, for example, amyloid-β accumulation, thereby accelerating cognitive decline and progression of Alzheimer-related changes in model systems of the disease. A better understanding of whether experiences early in life also modify trajectories of cognitive decline and pathology in AD and how the substrates discussed translate to humans may help develop novel preventive and/or therapeutic strategies to mitigate the consequences of stressors early in life and increase resilience to developing dementia.

Systems-Level Interactome Mapping Reveals Actionable Protein Network Dysregulation Across the Alzheimer's Disease Spectrum

Alzheimer's disease (AD) progresses as a continuum, from preclinical stages to late-stage cognitive decline, yet the molecular mechanisms driving this progression remain poorly understood. Here, we provide a systems-level map of protein-protein interaction (PPI) network dysfunction across the AD spectrum and uncover epichaperomes-stable scaffolding platforms formed by chaperones and co-factors-as central drivers of this process. Using over 100 human brain specimens, mouse models, and human neurons, we show that epichaperomes emerge early, even in preclinical AD, and progressively disrupt multiple PPI networks critical for synaptic function and neuroplasticity. Glutamatergic neurons, essential for learning and memory, exhibit heightened vulnerability, with their dysfunction driven by protein sequestration into epichaperome scaffolds, independent of changes in protein expression. Notably, pharmacological disruption of epichaperomes with PU-AD restores PPI network integrity and reverses synaptic and cognitive deficits, directly linking epichaperome-driven network dysfunction to AD pathology. These findings establish epichaperomes as key mediators of molecular collapse in AD and identify network-centric intervention strategies as a promising avenue for disease-modifying therapies.

Quantification and correlation of amyloid-β plaque load, glial activation, GABAergic interneuron numbers, and cognitive decline in the young TgF344-AD rat model of Alzheimer's disease

Background

Animal models of Alzheimer's disease (AD) are essential tools for investigating disease pathophysiology and conducting preclinical drug testing. In this study, we examined neuronal and glial alterations in the hippocampus and medial prefrontal cortex (mPFC) of young TgF344-AD rats and correlated these changes with cognitive decline and amyloid-β plaque load.

Methods

We compared TgF344-AD and non-transgenic littermate rats aged 7-8 months of age. We systematically quantified β-amyloid plaques, astrocytes, microglia, four different subtypes of GABAergic interneurons (calretinin-, cholecystokinin-, parvalbumin-, and somatostatin-positive neurons), and newly generated neurons in the hippocampus. Spatial learning and memory were assessed using the Barnes maze test.

Results

Young TgF344-AD rats had a large number of amyloid plaques in both the hippocampus and mPFC, together with a pronounced increase in microglial cell numbers. Astrocytic activation was significant in the mPFC. Cholecystokinin-positive cell numbers were decreased in the hippocampus of transgenic rats, but calretinin-, parvalbumin-, and somatostatin-positive cell numbers were not altered. Adult neurogenesis was not affected by genotype. TgF344-AD rats had spatial learning and memory impairments, but this cognitive deficit did not correlate with amyloid plaque number or cellular changes in the brain. In the hippocampus, amyloid plaque numbers were negatively correlated with cholecystokinin-positive neuron and microglial cell numbers. In the mPFC, amyloid plaque number was negatively correlated with the number of astrocytes.

Conclusion

Pronounced neuropathological changes were found in the hippocampus and mPFC of young TgF344-AD rats, including the loss of hippocampal cholecystokinin-positive interneurons. Some of these neuropathological changes were negatively correlated with amyloid-β plaque load, but not with cognitive impairment.

Combination of 3 probiotics restores attenuated adult neurogenesis in germ-free mice

Gut microbiota plays an important role in regulating brain function and adult neurogenesis. Although probiotics have recently been reported as effective against certain psychiatric disorders, the underlying mechanisms remain unclear. In particular, the combination of 3 probiotic strains, Bacillus subtilis TO-A, Enterococcus faecium T-110, and Clostridium butyricum TO-A, hereafter referred to as ProB3, has been reported to potentially alleviate psychiatric symptoms in patients with schizophrenia. Herein, we show that ProB3 promotes adult neurogenesis in mice and restores its dysregulation in germ-free (GF) mice. ProB3 colonization in GF mice enhanced the proliferation of adult neural stem cells compared to specific-pathogen-free and GF mice. Furthermore, ProB3 colonization was sufficient to ameliorate the arrest of newborn neuron maturation and the diminution of quiescent neural stem cells in GF mice. ProB3 colonization in mice increased the levels of several metabolites in the blood, including theanine and 3-hydroxybutyrate, and imidazole peptides, including anserine, which promoted proliferation, neurogenesis, and maturation of newborn neurons in cultured human fetus neural stem cells, as well as mouse adult hippocampal neural stem cells. Collectively, these results indicate that the essential role of the gut microbiota in adult hippocampal neurogenesis can be effectively complemented by the intake of a specific 3-strain probiotic, ProB3, providing novel insights into the brain-gut axis.

Decreasing β-Catenin Leads to Altered Endothelial Morphology, Increased Barrier Permeability and Cognitive Impairment During Chronic Methamphetamine Exposure

Cognitive impairment induced by chronic methamphetamine (METH) exposure exhibits similarities to neurodegenerative disorders and is associated with blood-brain barrier (BBB) dysfunction. However, the potential involvement of β-catenin in maintaining BBB integrity during METH exposure remains unexplored. In this study, Y-maze and novel object recognition tests were conducted to assess cognitive impairment in mice exposed chronically to methamphetamine for 2 and 4 weeks. Gd-DTPA and Evans blue leakage tests revealed disruption of the BBB in the hippocampus, while chronic METH exposure for 2 and 4 weeks significantly decreased β-catenin levels along with its transcriptionally regulated protein, claudin5. Additionally, various neural injury-related proteins, such as APP, Aβ1-42, p-tau (Thr181) and p-tau (Ser396), as well as neuroinflammation-related proteins, such as IL-6, IL-1β, and TNF-α, exhibited increased levels following chronic METH exposure. Furthermore, plasma analysis indicated elevated levels of p-Tau (total), neurofilament light chain, and GFAP. In vitro experiments demonstrated that exposure to METH resulted in dose-dependent and time-dependent reductions in cellular activity and connectivity of bEnd.3 and hcmec/D3 cells. Furthermore, β-catenin exhibited decreased levels and altered subcellular localization, transitioning from the cell membrane to the cytoplasm and nucleus upon METH exposure. Overexpression of β-catenin was found to alleviate endothelial toxicity and attenuate junctional weakening induced by METH. The aforementioned findings underscore the crucial involvement of β-catenin in endothelial cells during chronic METH exposure-induced disruption of the BBB, thereby presenting a potential novel target for addressing METH-associated cerebrovascular dysfunction and cognitive impairment.

Long-Term Effect of Intensive vs Standard Blood Pressure Control on Mild Cognitive Impairment and Probable Dementia in SPRINT

BACKGROUND AND OBJECTIVES

The Systolic Blood Pressure Intervention Trial suggested that intensive lowering of systolic blood pressure (SBP) decreases the risk of developing dementia. However, an insufficient number of probable dementia cases stemming from the trial's early termination made results inconclusive. The goal of this study was to estimate the effect of intensive vs standard SBP lowering on the longer term incidence of cognitive impairment leveraging extended follow-up for cognitive status.

METHODS

This is a prespecified secondary analysis of a randomized clinical trial. Between 2010 and 2013, patients aged 50 years and older with hypertension and increased cardiovascular risk excluding those with diabetes mellitus or history of stroke were recruited from 102 clinics in the United States and Puerto Rico. Participants were randomized to a SBP goal of <120 mm Hg (intensive treatment) or <140 mm Hg (standard treatment) and received treatment for 3.3 years. In-person cognitive assessment follow-up occurred through July 2018. Continued ascertainment of cognitive status by telephone began in December 2019 for participants who had not withdrawn consent or been previously adjudicated with probable dementia, but provided consent for future research. Data were analyzed using survival analyses.

RESULTS

Of 9,361 randomized participants, 7,221 (77%) were eligible to be re-contacted. Cognitive status of 4,232 (59%) was ascertained (mean age 67 years, 36% female). We accrued a total of 216 new cases of probable dementia, less than our target of 326. Over a median follow-up of 7 years, 248 participants of the intensive treatment group (8.5 per 1,000 person-years) were adjudicated with probable dementia, compared with 293 participants (10.2 per 1,000 person-years) in the standard treatment group (hazard ratio [HR], 0.86; 95% CI, 0.72-1.02). Consistent with earlier results from the trial, the rate of both mild cognitive impairment (MCI; HR, 0.87 95% CI, 0.76-1.00) and a composite of MCI or probable dementia was lower with intensive treatment (HR, 0.89; 95% CI, 0.79, 0.99).

DISCUSSION

Among ambulatory adults with hypertension and high cardiovascular risk, intensive treatment vs standard treatment of SBP for 3.3 years resulted in a lower risk of MCI and cognitive impairment including MCI or probable dementia, but not for probable dementia alone.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that intensively reducing SBP (target <120 mm Hg) decreases the risk of cognitive impairment in individuals aged 50 years and older with hypertension.

CLINICAL TRIAL INFORMATION

Clinical trial number NCT01206062.

Nose-to-brain delivery of DHA-loaded nanoemulsions: A promising approach against Alzheimer's disease

Reduced docosahexaenoic acid (DHA) concentrations seem to be associated with an increased risk of Alzheimer's disease (AD), and DHA accretion to the brain across the blood-brain-barrier (BBB) can be modulated by various factors. Therefore, there is an urgent need to identify an efficient and non-invasive method to ensure brain DHA enrichment. In the present study, a safe and stable DHA-enriched nanoemulsion, designed to protect DHA against oxidation, was designed and administered intranasally in a transgenic mouse model of AD, the J20 mice. Intranasal treatment with nanoformulated DHA significantly improved well-being and working spatial memory in six-months-old J20 mice. These behavioral effects were associated with a reduction of amyloid deposition, oxidative stress, and neuroinflammation in brain tissues, which may be partially due to DHA-induced inactivation of the pleiotropic kinase GSK3β. In conclusion, intranasal DHA administration exhibited strong therapeutic effects and disease-modifying benefits in the J20 AD model. Given that DHA has already shown safety and tolerability in healthy human subjects, our results further support the need for clinical trials to assess the potential of this approach in Alzheimer's patients.

Vascular amyloidβ load in the meningeal arterial network correlates with loss of cerebral blood flow and pial collateral vessel enlargement in the J20 murine model of Alzheimer's disease

INTRODUCTION

Global reduction in cerebral blood flow (CBF) is an early pathology in Alzheimer's disease, preceding significant plaque accumulation and neurological decline. Chronic reduced CBF and subsequent reduction in tissue oxygenation and glucose may drive neurodegeneration, yet the underlying cause of globally reduced CBF remains unclear.

METHODS

Using premortem delivery of Methoxy-XO4 to label Aβ, and arterial vascular labeling, we assessed Aβ burden on the pial artery/arteriole network and cerebral blood flow in aged male and female WT and J20 AD mice.

RESULTS

The pial artery/arteriole vascular network selectively displayed extensive vascular Aβ burden. Pial collateral arteriole vessels, the by-pass system that reroutes blood flow during occlusion, displayed significant enlargement in J20 mice. Despite this, CBF was decreased by approximately 15% in 12-month J20 mice when compared to WT littermates.

DISCUSSION

Significant Aβ burden on the meningeal arterial network may contribute to the restriction of CBF. Redistribution of CBF through enlarged pial collateral vessels may serve as a compensatory mechanism to alter CBF during disease progression in cases of CAA.

Human adult neurogenesis loss corresponds with cognitive decline during epilepsy progression

Mesial temporal lobe epilepsy (MTLE) is a syndromic disorder presenting with seizures and cognitive comorbidities. Although seizure etiology is increasingly understood, the pathophysiological mechanisms contributing to cognitive decline and epilepsy progression remain less recognized. We have previously shown that adult hippocampal neurogenesis dramatically declines in MTLE patients with increased disease duration. Here, we investigate when multiple cognitive domains become affected during epilepsy progression and how human neurogenesis levels contribute to it. We find that intelligence, verbal learning, and memory decline at a critical period of 20 years disease duration. In contrast to rodents, the number of human immature neurons positively associates with auditory verbal, rather than visuospatial, learning and memory. Moreover, this association does not apply to mature granule neurons. Our study provides cellular evidence of how adult neurogenesis corresponds with human cognition and signifies an opportunity to advance regenerative medicine for patients with MTLE and other cognitive disorders.

Synergistic effects of plasma S100B and MRI measures of cerebrovascular disease on cognition in older adults

There is growing interest in studying vascular contributions to cognitive impairment and dementia (VCID) and developing biomarkers to identify at-risk individuals. A combination of biofluid and neuroimaging markers may better profile early stage VCID than individual measures. Here, we tested this possibility focusing on plasma levels of S100 calcium-binding protein B (S100B), which has been linked with blood-brain-barrier (BBB) integrity, and neuroimaging measures assessing BBB function (water exchange rate across the BBB (kw)) and cerebral small vessel disease (white matter hyperintensities (WMHs)). A total of 74 older adults without dementia had plasma samples collected and underwent cognitive assessment. A subsample had neuroimaging data including diffusion prepared pseudo-continuous arterial spin labeling (DP-pCASL) for assessment of BBB kw and T2-weighted fluid-attenuated inversion recovery (FLAIR) for quantification of WMHs. Results indicated that higher plasma S100B levels were associated with poorer episodic memory performance (β = - .031, SE = .008, p < .001). Moreover, significant interactions were observed between plasma S100B levels and parietal lobe BBB kw (interaction β = .095, SE = .042, p = .028) and between plasma S100B levels and deep WMH volume (interaction β = - .025, SE = .009, p = .007) for episodic memory. Individuals with the poorest memory performance showed both high plasma S100B and either low BBB kw in the parietal lobe or increased deep WMH burden. Taken together, our results provide support for the combined use of biofluid and neuroimaging markers in the study of VCID.

Sex-specific influences of APOEε4 genotype on hippocampal neurogenesis and progenitor cells in middle-aged rats

BACKGROUND

Alzheimer's disease (AD) disproportionately and uniquely affects females, and these sex differences are further exacerbated by the presence of Apolipoprotein (APOE) ε4 alleles, the top genetic risk factor for late-onset AD. To expand our understanding about how late-onset AD risk might differentially influence males and females, this study explores how APOEε4 affects hippocampal neurogenesis and microglia, key neuroplastic markers involved in AD pathogenesis, differently by sex in middle-aged rats.

METHODS

A rat model expressing the humanized (h) APOEε4 allele was characterized to examine markers of adult neurogenesis (neural progenitor cells and new-born neurons) and immune cells (microglia) in the dentate gyrus of the hippocampus in 13 month-old male and female rats.

RESULTS

We observed basal sex differences in neurogenesis at middle age, as wildtype male rats had greater densities of neural progenitor cells and new-born neurons in the dentate gyrus than wildtype female rats. Male hAPOEε4 rats exhibited fewer neural progenitor cells, fewer new-born neurons, and more microglia than male wildtype rats. On the other hand, female hAPOEε4 rats exhibited more new-born neurons than female wildtype rats. Interestingly, females had more microglia than males regardless of genotype. Correlations were conducted to further elucidate any sex differences in the relationships between these biomarkers. Notably, there was a significant positive correlation between neural progenitor cells and new-born neurons, and a significant negative correlation between new-born neurons and microglia, but only in male rats.

CONCLUSION

In contrast to the clear pattern of effects of the hAPOEε4 risk factor on hippocampal neurogenesis in males, females had unaltered levels of neural progenitor cells and increased density of new-born neurons. Furthermore, relationships between neurogenesis and microglia were significantly correlated within males, and not females. This suggests that females may be presenting a compensatory response to the hAPOEε4 genotype at middle age. Collectively, these results exemplify the importance of thoroughly examining influences of sex on AD endophenotypes, as it may reveal sex-specific pathways and protective mechanisms relevant to AD.

Efficacy and molecular mechanisms of hesperidin in mitigating Alzheimer's disease: A systematic review

Hesperidin, a flavonoid glycoside, is a natural phenolic compound that has broad biological effects. Increasing evidence suggests that hesperidin inhibits the occurrence and development of neurodegenerative diseases, including Alzheimer's disease (AD). This article reviews the neuropharmacological mechanisms of hesperidin in the prevention and treatment of AD through in vitro and in vivo studies. A systematic review of preclinical studies was conducted using PubMed, Web of Science, Scopus, and Google Scholar (up to July 1, 2024). The neuroprotective potential of hesperidin was mediated through mechanisms such as inhibition of β-amyloid (Aβ) aggregation, enhancement of endogenous antioxidant defense functions, reduction of neuroinflammation and apoptosis, improvement of mitochondrial dysfunction, regulation of autophagy, and promotion of neurogenesis. Despite various preclinical studies on the role of hesperidin in AD, its exact effects on humans remain unclear. Few clinical trials have indicated that dietary supplements rich in hesperidin can improve cerebral blood flow, cognition, and memory performance. The neuroprotective effect of hesperidin may be exerted via regulating different molecular pathways, including the RAGE/NF-κB, Akt/Nrf2, and AMPK/BDNF/CREB pathways. However, further clinical trials are needed to confirm the neuroprotective effects of this natural flavonoid compound and to assess its safety.

Characteristics of Parthenogenetic Stem Cells and Their Potential Treatment Strategy for Central Nervous System Diseases

Stem cells hold significant promise in treating neurological illnesses, such as stroke, spinal cord injury and neurodegenerative diseases. The origins and characteristics of human parthenogenetic stem cells might lead to a new research area in treating nervous system diseases. The current clinical studies in the field of traumatic brain injury and neurodegenerative diseases are reviewed. Some variables that influence common stem cells' survival, proliferation, and therapeutic efficacy will be mentioned in this paper because they may play an important role in studying parthenogenetic stem cells.

An integrative analysis of ASCL1 in breast cancer and inhibition of ASCL1 increases paclitaxel sensitivity by activating ferroptosis via the CREB1/GPX4 axis

Objective

Our previous study found that Achaete-scute complex homolog 1 (ASCL1) is involved in classifying BC subtypes with different prognostic and pathological characteristics. However, the biological role of ASCL1 in BC still remains largely unexplored. This study aims to elucidate the function of ASCL1 in BC using bioinformatics analyses, as well as in vitro and in vivo experimental approaches.

Methods

Data from the TCGA, GEO, and Human Protein Atlas databases were utilized to evaluate ASCL1 expression in BC and its association with patient prognosis. Genetic alterations in ASCL1 were assessed through the COSMIC and cBioPortal databases, while the TIMER2.0 database provided insights into the relationship between ASCL1 expression and key gene mutations in BC. The GDSC database was used to examine correlations between ASCL1 levels and sensitivity to standard chemotherapeutic agents. Associations between ASCL1 expression and cytokines, immunomodulatory factors, MHC molecules, and receptors were analyzed using Pearson and Spearman correlation methods. The TIP database was employed to investigate the connection between ASCL1 expression and immunoreactivity scores, and six computational approaches were applied to evaluate immune cell infiltration. Functional assays were conducted on BC cell lines MCF-7 and MDA-MB-231, and nude mouse models were used for in vivo studies.

Results

ASCL1 was found to be upregulated in BC and correlated with unfavorable prognosis and mutations in key oncogenes. Its expression was linked to immunomodulatory factors, immune cell infiltration, and immunoreactivity scores in the tumor microenvironment. Additionally, ASCL1 influenced tumor immune dynamics and chemosensitivity in BC. Overexpression of ASCL1 enhanced BC cell proliferation, migration and invasion, while its knockdown had the opposite effect. Notably, inhibition of ASCL1 increased BC cell sensitivity to paclitaxel both in vitro and in vivo. In addition, inhibition of ASCL1 activated ferroptosis in BC, including altered mitochondrial morphology, increased MDA and ROS levels, decreased GSH levels and reduced GSH/GSSG ratio. Mechanistically, inhibition of ASCL1 decreases the phosphorylation of CREB1, thus reducing the expression of GPX4. In summary, inhibition of ASCL1 increases paclitaxel sensitivity by activating ferroptosis via the CREB1/GPX4 axis.

Conclusions

ASCL1 exerts oncogenic effects in BC and represents a potential therapeutic target for intervention.

Cross-Species Insights from Single-Nucleus Sequencing Highlight Aging-Related Hippocampal Features in Tree Shrew

The tree shrew brain has garnered considerable attention due to its remarkable similarities to human brain. However, the cellular composition and genetic signatures of tree shrew hippocampus across postnatal life remain poorly characterized. Here, we establish the first single-nucleus transcriptomic atlas of tree shrew hippocampus spanning postnatal life, detailing the dynamics and diversity of the neurogenic lineage, oligodendrocytes, microglia, and endothelial cells. Notably, cross-species transcriptomic comparison among humans, macaques, tree shrews, and mice reveals that the tree shrew transcriptome resembles that of macaques, making it a promising model for simulating human neurological diseases. More interestingly, we identified a unique class of tree shrew-specific neural stem cells and established SOX6, ADAMTS19, and MAP2 as their markers. Furthermore, aberrant gene expression and cellular dysfunction in the tree shrew hippocampus are linked to neuroinflammation and cognitive impairment during tree shrew aging. Our study provides extensive resources on cell composition and transcriptomic profiles, serving as a foundation for future research on neurodevelopmental and neurological disorders in tree shrews.

Analysis of CA1, CA3, and DG areas of the hippocampus, substance-P, and brain-derived neurotrophic factors expression in the presence of Ocimum sanctum Linn on the brain of the rat model Alzheimer's disease

Background

Alzheimer's disease (AD) is a progressive neurological condition characterized by impaired cognitive dysfunction and abnormal behavior. Thirty-five million individuals worldwide suffer from dementia, making it the most frequent cause of dementia. Canine cognitive dysfunction (CCD) affects 28% of dogs aged 11-12 years. It is a prevalent disease in canines. Amyloid-β peptides accumulate neurotoxicity, resulting in problems in the central nervous system and neurotransmitters. Treatments for both AD and CCD have not yet shown acceptable outcomes. It is crucial to comprehend disease mechanisms and identify novel therapeutics using animal models.

Aim

Using a rat model of AD, this study attempted to determine the effects of an ethanolic extract from Ocimum sanctum on the number and shape of neurons in the CA1, CA3, and DG sections of the hippocampus along with the expression of neurotrophic factors.

Methods

The animal model will be split into five treatment groups, one of which will be a control group. The treatments will be administered for 14, 21, and 28 days, and samples will be analyzed by BDNF by ELISA, SP expression by immunohistochemical staining, and the number of neurons in CA1, CA3, and DG using cresyl violet staining.

Results

Results of the study revealed increased neuronal density in the CA1, CA3, and DG regions, and these neurons were more highly expressed in the neurotrophic factor BDNF and neuropeptide SP.

Conclusion

By upregulating the expression of SP and BDNF, the ethanolic extract of O. sanctum increased the neuronal counts (pyramidal and granular cells) in the hippocampal CA1, CA3, and DG regions.

Inhibition of IFITM3 in cerebrovascular endothelium alleviates Alzheimer's-related phenotypes

INTRODUCTION

Interferon-induced transmembrane protein 3 (IFITM3) modulates γ-secretase in Alzheimer's Disease (AD). Although IFITM3 knockout reduces amyloid β protein (Aβ) production, its cell-specific effect on AD remains unclear.

METHODS

Single nucleus RNA sequencing (snRNA-seq) was used to assess IFITM3 expression. Adeno-associated virus-BI30 (AAV-BI30) was injected to reduce IFITM3 expression in the cerebrovascular endothelial cells (CVECs). The effects on AD phenotypes in cells and AD mice were examined through behavioral tests, two-photon imaging, flow cytometry, Western blot, immunohistochemistry, and quantitative polymerase chain reaction assay (qPCR).

RESULTS

IFITM3 expression was increased in the CVECs of patients with AD. Overexpression of IFITM3 in primary endothelial cells enhanced Aβ generation through regulating beta-site APP cleaving enzyme 1 (BACE1) and γ-secretase. Aβ further increased IFITM3 expression, creating a vicious cycle. Knockdown of IFITM3 in CVECs decreased Aβ accumulation within cerebrovascular walls, reduced Alzheimer's-related pathology, and improved cognitive performance in AD transgenic mice.

DISCUSSION

Knockdown of IFITM3 in CVECs alleviates AD pathology and cognitive impairment. Targeting cerebrovascular endothelial IFITM3 holds promise for AD treatment.

HIGHLIGHTS

Interferon-induced transmembrane protein 3 (IFITM3) expression was increased in the cerebrovascular endothelial cells (CVECs) of patients with Alzheimer's Disease (AD). Cerebrovascular endothelial IFITM3 regulates amyloid β protein (Aβ) generation through regulating beta-site APP cleaving enzyme 1 (BACE1) and γ-secretase. Knockdown of IFITM3 in CVECs reduces Aβ deposits and improves cognitive impairments in AD transgenic mice. Cerebrovascular endothelial IFITM3 could be a potential target for the treatment of AD.

The potential of circulating nonesterified fatty acids and sphingolipids in the biological understanding of cognitive decline and dementia

PURPOSE OF REVIEW

Cognitive decline and late-onset dementia pose significant challenges in aging societies, and many dementia cases could be prevented or delayed through modification of associated risk factors, many of which are tied to cardiovascular and metabolic dysfunction. As individuals age, the blood-brain barrier becomes more permeable, easing the exchange of molecules between the bloodstream and the brain. Consequently, blood-based biological markers (so-called biomarkers) provide a minimally invasive and accessible means of accessing molecular changes associated with aging and neurodegeneration.

RECENT FINDINGS

Circulating free fatty acids, also called nonesterified fatty acids (NEFAs), and sphingolipids are associated with cardiovascular disease, insulin resistance, and diabetes; thus, could be promising candidates as biomarkers for cognitive decline and dementia.

SUMMARY

The opportunity to study such minimally invasive biomarkers further opens up potential new avenues for improved understanding of the underlying biology of diseases of the brain.

Upstream regulation of microRNA-9 through a complex cellular machinery during neurogenesis

While microRNAs (miRs) like miR-9 are crucial for neurogenesis and neuronal differentiation, their regulatory mechanisms are not well understood. miR-9 is highly expressed in the brain and plays a significant role in neurogenesis. Using the Collaborative Cross resource, we identified significant quantitative trait loci (QTL) through genetic analyses. We then characterized over 130 candidate genes within these QTL regions using RNA interference, qPCR, and neuronal differentiation assays, narrowing them down to 13 promising candidates. Among these, Panx2, Polr1c, and Mgea5 were found to colocalize in the neurogenic niches of the SVZ and DG regions, as shown by immunofluorescence. Further ChIP-seq and Co-IP analyses revealed their interaction and binding to the miR-9 locus, forming a DNA-protein regulatory complex we termed 'miRSome-9.' A 3C/ChIP-loop assay confirmed the chromatin organization of miRSome-9 at the miR-9 locus, shedding light on the upstream mechanisms regulating miR-9 expression during neurogenesis.

Gamma-glutamyl transferase 5 overexpression in cerebrovascular endothelial cells improves brain pathology, cognition, and behavior in APP/PS1 mice

JOURNAL/nrgr/04.03/01300535-202502000-00030/figure1/v/2024-05-28T214302Z/r/image-tiff In patients with Alzheimer's disease, gamma-glutamyl transferase 5 (GGT5) expression has been observed to be downregulated in cerebrovascular endothelial cells. However, the functional role of GGT5 in the development of Alzheimer's disease remains unclear. This study aimed to explore the effect of GGT5 on cognitive function and brain pathology in an APP/PS1 mouse model of Alzheimer's disease, as well as the underlying mechanism. We observed a significant reduction in GGT5 expression in two in vitro models of Alzheimer's disease (Aβ1-42-treated hCMEC/D3 and bEnd.3 cells), as well as in the APP/PS1 mouse model. Additionally, injection of APP/PS1 mice with an adeno-associated virus encoding GGT5 enhanced hippocampal synaptic plasticity and mitigated cognitive deficits. Interestingly, increasing GGT5 expression in cerebrovascular endothelial cells reduced levels of both soluble and insoluble amyloid-β in the brains of APP/PS1 mice. This effect may be attributable to inhibition of the expression of β-site APP cleaving enzyme 1, which is mediated by nuclear factor-kappa B. Our findings demonstrate that GGT5 expression in cerebrovascular endothelial cells is inversely associated with Alzheimer's disease pathogenesis, and that GGT5 upregulation mitigates cognitive deficits in APP/PS1 mice. These findings suggest that GGT5 expression in cerebrovascular endothelial cells is a potential therapeutic target and biomarker for Alzheimer's disease.

The role of resveratrol in neurogenesis: a systematic review

CONTEXT

Resveratrol (RV) is a natural compound found in grapes, wine, berries, and peanuts and has potential health benefits-namely, neurogenesis improvement. Neurogenesis, which is the process through which new neurons or nerve cells are generated in the brain, occurs in the subventricular zone and hippocampus and is influenced by various factors. RV has been shown to increase neural stem cell proliferation and survival, improving cognitive function in hippocampus-dependent tasks. Thus, to provide a convergent and unbiased conclusion of the available evidence on the correlation between the RV and neurogenesis, a systematic review needs to be undertaken meticulously and with appropriate attention.

OBJECTIVE

This study aimed to systematically review any potential connection between the RV and neurogenesis in animal models.

DATA SOURCES AND EXTRACTION

Based on the particular selection criteria, 8 original animal studies that investigated the relationship between RV and neurogenesis were included. Studies written in English and published in peer-reviewed journals with no restrictions on the starting date of publication on August 17, 2023, were searched in the Google Scholar and PubMed databases. Furthermore, data were extracted and analyzed independently by 2 researchers and then reviewed by a third researcher, and discrepancies were resolved by consensus. This project followed PRISMA reporting standards.

DATA ANALYSIS

In the studies analyzed in this review, there is a definite correlation between RV and neurogenesis, meaning that RV intake, irrespective of the mechanisms thereof, can boost neurogenesis in both the subventricular zone and hippocampus.

CONCLUSION

This finding, albeit with some limitations, provides a plausible indication of RV's beneficial function in neurogenesis. Indeed, RV intake may result in neurogenesis benefits-namely, cognitive function, mood regulation, stress resilience, and neuroprotection, potentially preventing cognitive decline.

The Beneficial Effects of Combined Exercise and Polyphenols in Alzheimer's Disease

Regular exercise enhances life quality, lowers the risk of cognitive damage, and slows the advancement of Alzheimer's disease (AD). Natural compounds rich in polyphenols have garnered attention as a non-pharmacological means of treating and preventing AD. The primary component of wine, grape seeds, and nuts is polyphenols. Research suggests that polyphenols slow down the rate of neurodegeneration in AD and lessen learning impairment. Furthermore, polyphenols lessen brain impairments related to cognition. Additionally, polyphenols can specifically restructure amyloid-β (Aβ) structures and soluble oligomers into non-toxic alternative species. They have also been revealed to increase brain-derived neurotrophic factors expression, suggesting that they have a positive impact on the creation of neurotrophins. The benefits of polyphenol supplementation and exercise, which can both provide neuroprotection, have not been well studied in AD patients. This review aimed to investigate the effects of combined exercise polyphenols on inflammation, neuroprotection, several conformational toxic species of Aβ, and Aβ-induced apoptosis in AD.

Uncovering the intricacies of O-GlcNAc modification in cognitive impairment: New insights from regulation to therapeutic targeting

O-linked β-N-acetylglucosamine (O-GlcNAc) represents a post-translational modification that occurs on serine or threonine residues on various proteins. This conserved modification interacts with vital cellular pathways. Although O-GlcNAc is widely distributed throughout the body, it is particularly enriched in the brain, where most proteins are O-GlcNAcylated. Recent studies have established a causal link between O-GlcNAc regulation in the brain and alterations in neurophysiological function. Alterations in O-GlcNAc levels in the brain are associated with the pathogenesis of several neurogenic diseases that can lead to cognitive impairment. Remarkably, manipulation of O-GlcNAc levels demonstrated a protective effect on cognitive function. Although the precise molecular mechanism of O-GlcNAc modification in the nervous system remains elusive, its regulation is fundamental to multiple neural and cognitive functions, fluctuating levels during normal and pathological cognitive processes. In this review, we highlight the significant functional importance of O-GlcNAc modification in pathological cognitive impairments and the potential application of O-GlcNAc as a promising target for the intervention or amelioration of cognitive impairments.

Unraveling the transcriptomic landscape of brain vascular cells in dementia: A systematic review

INTRODUCTION

Cerebrovascular dysfunction plays a critical role in the pathogenesis of dementia and related neurodegenerative disorders. Recent omics-driven research has revealed associations between vascular abnormalities and transcriptomic alterations in brain vascular cells, particularly endothelial cells (ECs) and pericytes (PCs). However, the impact of these molecular changes on dementia remains unclear.

METHODS

We conducted a comparative analysis of gene expression in ECs and PCs across neurodegenerative conditions, including Alzheimer's disease (AD), Huntington's disease, and arteriovenous malformation, utilizing transcriptomic data from published postmortem human tissue studies.

RESULTS

We identified differentially expressed genes (DEGs) consistently dysregulated in ECs and PCs across these pathologies. Notably, several DEGs are linked to vascular cell zonation and genetic risks for AD and cerebral small vessel disease.

DISCUSSION

Our findings provide insights into the cellular and molecular mechanisms underlying vascular dysfunction in dementia, highlight the knowledge gaps, and suggest potential novel vascular therapeutic targets, including genes not previously investigated in this context.

HIGHLIGHTS

Systematic review of differentially expressed genes (DEGs) in vascular cells from neurodegenerative single-nuclear RNA-sequencing (snRNA-seq) studies. Identify overlapping DEGs in multiple vascular cell types across studies. Examine functional relevance and associations with genetic risk for common DEGs. Outline future directions for the vascular omics field.