Alzheimer's disease: clinical update on epidemiology, pathophysiology and diagnosis

Protein arginine methyltransferase 4 modulates nitric oxide synthase uncoupling and cerebral blood flow in Alzheimer's disease

Alzheimer's disease (AD) is the leading cause of mortality, disability, and long-term care burden in the United States, with women comprising the majority of AD diagnoses. While AD-related dementia is associated with tau and amyloid beta accumulation, concurrent derangements in cerebral blood flow have been observed alongside these proteinopathies in humans and rodent models. The homeostatic production of nitric oxide synthases (NOS) becomes uncoupled in AD which leads to decreased NO-mediated vasodilation and oxidative stress via the production of peroxynitrite (ONOO-∙) superoxide species. Here, we investigate the role of the novel protein arginine methyltransferase 4 (PRMT4) enzyme function and its downstream product asymmetric dimethyl arginine (ADMA) as it relates to NOS dysregulation and cerebral blood flow in AD. ADMA (type-1 PRMT product) has been shown to bind NOS as a noncanonic ligand causing enzymatic dysfunction. Our results from RT-qPCR and protein analyses suggest that aged (9-12 months) female mice bearing tau- and amyloid beta-producing transgenic mutations (3xTg-AD) express higher levels of PRMT4 in the hippocampus when compared to age- and sex-matched C57BL6/J mice. In addition, we performed studies to quantify the expression and activity of different NOS isoforms. Furthermore, laser speckle contrast imaging analysis was indicative that 3xTg-AD mice have dysfunctional NOS activity, resulting in reduced production of NO metabolites, enhanced production of free-radical ONOO-, and decreased cerebral blood flow. Notably, the aforementioned phenomena can be reversed via pharmacologic PRMT4 inhibition. Together, these findings implicate the potential importance of PRMT4 signaling in the pathogenesis of Alzheimer's-related cerebrovascular derangement.

The Role of RIN3 Gene in Alzheimer's Disease Pathogenesis: a Comprehensive Review

Alzheimer's disease (AD) is a globally prevalent form of dementia that impacts diverse populations and is characterized by progressive neurodegeneration and impairments in executive memory. Although the exact mechanisms underlying AD pathogenesis remain unclear, it is commonly accepted that the aggregation of misfolded proteins, such as amyloid plaques and neurofibrillary tau tangles, plays a critical role. Additionally, AD is a multifactorial condition influenced by various genetic factors and can manifest as either early-onset AD (EOAD) or late-onset AD (LOAD), each associated with specific gene variants. One gene of particular interest in both EOAD and LOAD is RIN3, a guanine nucleotide exchange factor. This gene plays a multifaceted role in AD pathogenesis. Firstly, upregulation of RIN3 can result in endosomal enlargement and dysfunction, thereby facilitating the accumulation of beta-amyloid (Aβ) peptides in the brain. Secondly, RIN3 has been shown to impact the PICLAM pathway, affecting transcytosis across the blood-brain barrier. Lastly, RIN3 has implications for immune-mediated responses, notably through its influence on the PTK2B gene. This review aims to provide a concise overview of AD and delve into the role of the RIN3 gene in its pathogenesis.

Aerobic exercise attenuates LPS-induced cognitive dysfunction by reducing oxidative stress, glial activation, and neuroinflammation

Physical activity has been considered an important non-medication intervention in preserving mnemonic processes during aging. However, how aerobic exercise promotes such benefits for human health remains unclear. In this study, we aimed to explore the neuroprotective and anti-inflammatory effects of aerobic exercise against lipopolysaccharide (LPS)-induced amnesic C57BL/6J mice and BV-2 microglial cell models. In the in vivo experiment, the aerobic exercise training groups were allowed to run on a motorized treadmill 5 days/week for 4 weeks at a speed of 10 rpm/min, with LPS (0.1 mg/kg) intraperitoneally injected once a week for 4 weeks. We found that aerobic exercise ameliorated memory impairment and cognitive deficits among the amnesic mice. Correspondingly, aerobic exercise significantly increased the protein expressions of FNDC5, which activates target neuroprotective markers BDNF and CREB, and antioxidant markers Nrf2/HO-1, leading to inhibiting microglial-mediated neuroinflammation and reduced the expression of BACE-1 in the hippocampus and cerebral cortex of amnesic mice. We estimated that aerobic exercise inhibited neuroinflammation in part through the action of FNDC5/irisin on microglial cells. Therefore, we explored the anti-inflammatory effects of irisin on LPS-stimulated BV-2 microglial cells. In the in vitro experiment, irisin treatment blocked NF-κB/MAPK/IRF3 signaling activation concomitantly with the significantly lowered levels of the LPS-induced iNOS and COX-2 elevations and promotes the Nrf2/HO-1 expression in the LPS-stimulated BV-2 microglial cells. Together, our findings suggest that aerobic exercise can improve the spatial learning ability and cognitive functions of LPS-treated mice by inhibiting microglia-mediated neuroinflammation through its effect on the expression of BDNF/FNDC5/irisin.

Chuanzhitongluo capsule improves cognitive impairment in mice with chronic cerebral hypoperfusion via the cholinergic anti-inflammatory pathway

Vascular cognitive impairment (VCI) has become a common disease-causing cognitive deficit in humans, second only to Alzheimer's Disease (AD). Chuanzhitongluo capsule (CZTL) is a Traditional Chinese Medicine (TCM) preparation known for its effective protection against cerebral ischemia. However, its potential to ameliorate VCI remains unclear. This study aimed to investigate the cognitive improvement effects of CZTL in a mouse model of VCI. Chronic cerebral hypoperfusion (CCH) was induced in mice by bilateral common carotid artery stenosis (BCAS) to simulate the pathological changes associated with VCI. Spatial learning and memory abilities were assessed using the Morris Water Maze (MWM). RNA sequencing (RNA-Seq) was employed to identify differentially expressed genes (DEGs) in the hippocampus. Levels of inflammatory factors were measured through enzyme-linked immunosorbent assay (ELISA), while immunofluorescence (IF) determined the expression intensity of target proteins. Western Blot (WB) confirmed the final action pathway. Results indicated that CZTL significantly improved the spatial learning and memory abilities of CCH mice, along with alterations in gene expression profiles in the hippocampus. It also reduced neuroinflammation in the hippocampus and upregulated the choline acetyltransferase (ChAT) and α7 subunit-containing nicotinic acetylcholine receptor (α7nAChR), which are in synaptic plasticity and neuronal development. Moreover, CZTL inhibited the NF-κB signaling pathway. In conclusion, CZTL may alleviate neuroinflammation induced by CCH and improve cognitive impairment in CCH mice by regulating the cholinergic anti-inflammatory pathway (CAIP) involving ChAT/α7nAChR/NF-κB.

Trace Elements in Alzheimer's Disease and Dementia: The Current State of Knowledge

Changes in trace element concentrations are being wildly considered when it comes to neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease. This study aims to present the role that trace elements play in the central nervous system. Moreover, we reviewed the mechanisms involved in their neurotoxicity. Low zinc concentrations, as well as high levels of copper, manganese, and iron, activate the signalling pathways of the inflammatory, oxidative and nitrosative stress response. Neurodegeneration occurs due to the association between metals and proteins, which is then followed by aggregate formation, mitochondrial disorder, and, ultimately, cell death. In Alzheimer's disease, low Zn levels suppress the neurotoxicity induced by β-amyloid through the selective precipitation of aggregation intermediates. High concentrations of copper, iron and manganese cause the aggregation of intracellular α-synuclein, which results in synaptic dysfunction and axonal transport disruption. Parkinson's disease is caused by the accumulation of Fe in the midbrain dopaminergic nucleus, and the pathogenesis of multiple sclerosis derives from Zn deficiency, leading to an imbalance between T cell functions. Aluminium disturbs the homeostasis of other metals through a rise in the production of oxygen reactive forms, which then leads to cellular death. Selenium, in association with iron, plays a distinct role in the process of ferroptosis. Outlining the influence that metals have on oxidoreduction processes is crucial to recognising the pathophysiology of neurodegenerative diseases and may provide possible new methods for both their avoidance and therapy.

Scutellaria baicalensis Georgi stems and leaves flavonoids promote neuroregeneration and ameliorate memory loss in rats through cAMP-PKA-CREB signaling pathway based on network pharmacology and bioinformatics analysis

The aim of this study was to investigate the possible molecular mechanism of Scutellaria baicalensis Georgi stems and leaves flavonoids (SSF) in Alzheimer's disease (AD). The active ingredients of SSF and their targets were identified via network pharmacology and bioinformatics analysis. To test the successful establishment of a rat model of AD by Aβ25-35 combined with RHTGF-β1 and AlCl3, the Morris water maze test was used. To intervene, three different doses of SSF were administered. The model group and the control group were included among the parallel groups. A shuttle box test, immunohistochemistry, an enzyme-linked immunosorbent assay, qPCR and Western blot were performed to verify the results. Based on the intersection of genes among AD disease targets, SSF component targets, and differentially expressed genes in the single cell dataset GSE138852 and bulk-seq dataset GSE5281, nine genes related to the action of SSF on AD were identified. SSF have an important anti-AD pathway in the cAMP signaling pathway. SSF can ameliorate the conditioned memory impairment, augment Brdu protein expression and cAMP content; and differentially regulate the mRNA and protein expressions of GPCR, Gαs, AC1, PKA, and VEGF. The cAMP-PKA-CREB pathway in the SSF may mediate the ability of the SSF to ameliorate the composite-induced memory loss and nerve regeneration in rats induced by composite Aβ.

The clinical efficacy of Olibanum gum chewing in patients with Mild-to-Moderate Alzheimer disease: A randomized Parallel-Design controlled trial

BACKGROUND

Alzheimer's disease is a common neurodegenerative disorder in elderly with progressive decline in cognitive functions. This study aimed to investigate the possible memory-improving effects of Olibanum on patients with Alzheimer's disease.

RESEARCH DESIGN AND METHOD

This double-blind, randomized clinical trial was carried out on 72 participants aged 50-75 years. The intervention group (n = 36) received 1.6 g/day of olibanum chewing gum for 18 weeks. The placebo group (n = 36) received chewing gum without olibanum. Neuropsychological assessments were performed at baseline, every 4 weeks, and after 18 weeks of the intervention.

RESULTS

There was no significant difference between (MD: 0.84, 95%CI: -1.10 to 2.78, p = 0.392) at baseline. Both groups had linear improvements over time. There was no significant difference between two groups regarding the improvements after the intervention (F = 0.157, p = 0.693). There were no significant differences between the groups for MMSE score (Mini-Mental State Examination) after the intervention (F = 0.141, p = 0.708).

CONCLUSIONS

This study revealed that 18 weeks of gum chewing with Olibanum did not change the neuropsychological status. More clinical studies are needed to confirm these findings.

Neuroprotective potentials of Lead phytochemicals against Alzheimer's disease with focus on oxidative stress-mediated signaling pathways: Pharmacokinetic challenges, target specificity, clinical trials and future perspectives

BACKGROUND

Alzheimer's diseases (AD) and dementia are among the highly prevalent neurological disorders characterized by deposition of beta amyloid (Aβ) plaques, dense deposits of highly phosphorylated tau proteins, insufficiency of acetylcholine (ACh) and imbalance in glutamatergic system. Patients typically experience cognitive, behavioral alterations and are unable to perform their routine activities. Evidence also suggests that inflammatory processes including excessive microglia activation, high expression of inflammatory cytokines and release of free radicals. Thus, targeting inflammatory pathways beside other targets might be the key factors to control- disease symptoms and progression.

PURPOSE

This review is aimed to highlight the mechanisms and pathways involved in the neuroprotective potentials of lead phytochemicals. Further to provide updates regarding challenges associated with their use and their progress into clinical trials as potential lead compounds.

METHODS

Most recent scientific literature on pre-clinical and clinical data published in quality journals especially on the lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin was collected using SciFinder, PubMed, Google Scholar, Web of Science, JSTOR, EBSCO, Scopus and other related web sources.

RESULTS

Literature review indicated that the drug discovery against AD is insufficient and only few drugs are clinically approved which have limited efficacy. Among the therapeutic options, natural products have got tremendous attraction owing to their molecular diversity, their safety and efficacy. Research suggest that natural products can delay the disease onset, reduce its progression and regenerate the damage via their anti-amyloid, anti-inflammatory and antioxidant potentials. These agents regulate the pathways involved in the release of neurotrophins which are implicated in neuronal survival and function. Highly potential lead phytochemicals including curcumin, catechins, quercetin, resveratrol, genistein and apigenin regulate neuroprotective signaling pathways implicated in neurotrophins-mediated activation of tropomyosin receptor kinase (Trk) and p75 neurotrophins receptor (p75NTR) family receptors.

CONCLUSIONS

Phytochemicals especially phenolic compounds were identified as highly potential molecules which ameliorate oxidative stress induced neurodegeneration, reduce Aβ load and inhibit vital enzymes. Yet their clinical efficacy and bioavailability are the major challenges which need further interventions for more effective therapeutic outcomes.

Treadmill exercise can regulate the redox balance in the livers of APP/PS1 mice and reduce LPS accumulation in their brains through the gut-liver-kupffer cell axis

A growing body of clinical data has shown that patients with Alzheimer's disease (AD) have symptoms such as liver dysfunction and microbial-gut-brain axis dysfunction in addition to brain pathology, presenting a systemic multisystemic pathogenesis. Considering the systemic benefits of exercise, here, we first observed the effects of long-term treadmill exercise on liver injuries in APP/PS1 transgenic AD mice and explored the potential mechanisms of the gut-liver-brain axis's role in mediating exercise's ability to reduce bacterial lipopolysaccharide (LPS) pathology in the brain. The results showed that the livers of the AD mice were in states of oxidative stress, while the mice after long-term treadmill exercise showed alleviation of their oxidative stress, their intestinal barriers were protected, and the ability of their Kupffer cells to hydrolyze LPS was improved, in addition to the accumulation of LPS in their brains being reduced. Notably, the livers of the AD mice were in immunosuppressed states, with lower pro-oxidative and antioxidative levels than the livers of the wild-type mice, while exercise increased both their oxidative and antioxidative levels. These results suggest that long-term exercise modulates hepatic redox homeostasis in AD mice, attenuates oxidative damage, and reduces the accumulation of LPS in the brain through the combined action of the intestine-liver-Kupffer cells.

Discovering biomarkers associated and predicting cardiovascular disease with high accuracy using a novel nexus of machine learning techniques for precision medicine

Personalized interventions are deemed vital given the intricate characteristics, advancement, inherent genetic composition, and diversity of cardiovascular diseases (CVDs). The appropriate utilization of artificial intelligence (AI) and machine learning (ML) methodologies can yield novel understandings of CVDs, enabling improved personalized treatments through predictive analysis and deep phenotyping. In this study, we proposed and employed a novel approach combining traditional statistics and a nexus of cutting-edge AI/ML techniques to identify significant biomarkers for our predictive engine by analyzing the complete transcriptome of CVD patients. After robust gene expression data pre-processing, we utilized three statistical tests (Pearson correlation, Chi-square test, and ANOVA) to assess the differences in transcriptomic expression and clinical characteristics between healthy individuals and CVD patients. Next, the recursive feature elimination classifier assigned rankings to transcriptomic features based on their relation to the case-control variable. The top ten percent of commonly observed significant biomarkers were evaluated using four unique ML classifiers (Random Forest, Support Vector Machine, Xtreme Gradient Boosting Decision Trees, and k-Nearest Neighbors). After optimizing hyperparameters, the ensembled models, which were implemented using a soft voting classifier, accurately differentiated between patients and healthy individuals. We have uncovered 18 transcriptomic biomarkers that are highly significant in the CVD population that were used to predict disease with up to 96% accuracy. Additionally, we cross-validated our results with clinical records collected from patients in our cohort. The identified biomarkers served as potential indicators for early detection of CVDs. With its successful implementation, our newly developed predictive engine provides a valuable framework for identifying patients with CVDs based on their biomarker profiles.

The Effect of Apathy and Depressive Syndromes on Functional Outcomes in Alzheimer's Disease

Background

Alzheimer's disease (AD) is the most common cause of dementia. Its initially characterized by progressive short-term memory loss followed by cross-domain cognitive decline in later stages resulting in significant functional deficits and loss of activities of daily living (ADLs) independence. Apathy and depression are frequent neuropsychiatric sequelae in AD, but their contribution to functional deficits is poorly understood.

Objective

We aimed to quantitatively investigate if apathy and depressive symptoms predict ADLs in AD. We also wanted to fractionate apathy dimensions by factor-analyzing the apathy evaluation scale (AES) and then investigate the dimensions' relation to ADLs.

Methods

We recruited a sample of 115 patients with probable or possible AD and assessed them for depression, apathy, and ADLs alongside other measures. We hypothesized that apathy and depressive symptoms would predict ADLs and that AES items will load into cognitive, behavioral, and affective factors that would differentially relate to ADLs.

Results

Our results indicated that apathy symptoms predict ADLs deficits. The AES items resolved into a three-factor solution but the manner of clustering diverged from that proposed by AES authors. When these factors were regressed simultaneously, only behavioral apathy predicted global ADLs. Distinguishing basic from instrumental ADLs showed that behavioral and cognitive apathy symptoms associate with ADLs deficits while affective symptoms do not.

Conclusions

Our results highlight the influence of apathy on ADLs in AD. This has important implications for patient care considering the high prevalence of apathy in AD and other dementing illnesses.

Risk, protective, and biomarkers of dementia in Indigenous peoples: A systematic review

INTRODUCTION

Dementia is an emergent health priority for Indigenous peoples worldwide, yet little is known about disease drivers and protective factors.

METHODS

Database searches were conducted in March 2022 to identify original publications on risk, protective, genetic, neuroradiological, and biological factors related to dementia and cognitive impairment involving Indigenous peoples.

RESULTS

Modifiable risk factors featured across multiple studies include childhood adversity, hearing loss, low education attainment, unskilled work history, stroke, head injury, epilepsy, diabetes, hypertension, hyperlipidemia, depression, low BMI, poor mobility, and continence issues. Non-modifiable risk factors included increasing age, sex, and genetic polymorphisms. Education, ex-smoking, physical and social activity, and engagement with cultural or religious practices were highlighted as potential protective factors. There is a paucity of research on dementia biomarkers involving Indigenous peoples.

DISCUSSION

Greater understanding of modifiable factors and biomarkers of dementia can assist in strength-based models to promote healthy ageing and cognition for Indigenous peoples.

Single-Cell Sequencing Technology and Its Application in the Study of Central Nervous System Diseases

The mammalian central nervous system consists of a large number of cells, which contain not only different types of neurons, but also a large number of glial cells, such as astrocytes, oligodendrocytes, and microglia. These cells are capable of performing highly refined electrophysiological activities and providing the brain with functions such as nutritional support, information transmission and pathogen defense. The diversity of cell types and individual differences between cells have brought inspiration to the study of the mechanism of central nervous system diseases. In order to explore the role of different cells, a new technology, single-cell sequencing technology has emerged to perform specific analysis of high-throughput cell populations, and has been continuously developed. Single-cell sequencing technology can accurately analyze single-cell expression in mixed-cell populations and collect cells from different spatial locations, time stages and types. By using single-cell sequencing technology to compare gene expression profiles of normal and diseased cells, it is possible to discover cell subsets associated with specific diseases and their associated genes. Therefore, scientists can understand the development process, related functions and disease state of the nervous system from an unprecedented depth. In conclusion, single-cell sequencing technology provides a powerful technology for the discovery of novel therapeutic targets for central nervous system diseases.

Exploring the therapeutic potential of natural compounds modulating the endocannabinoid system in various diseases and disorders: review

Cannabinoid receptors, endogenous cannabinoids (endocannabinoids), and the enzymes involved in the biosynthesis and degradation of the endocannabinoids make up the endocannabinoid system (ECS). The components of the ECS are proven to modulate a vast bulk of various physiological and pathological processes due to their abundance throughout the human body. Such discoveries have attracted the researchers' attention and emerged as a potential therapeutical target for the treatment of various diseases. In the present article, we reviewed the discoveries of natural compounds, herbs, herbs formula, and their therapeutic properties in various diseases and disorders by modulating the ECS. We also summarize the molecular mechanisms through which these compounds elicit their properties by interacting with the ECS based on the existing findings. Our study provides the insight into the use of natural compounds that modulate ECS in various diseases and disorders, which in turn may facilitate future studies exploiting natural lead compounds as novel frameworks for designing more effective and safer therapeutics.

Neuroprotective potential of sevoflurane against isoflurane induced cognitive dysfunction in rats via anti-inflammatory and antioxidant effect

PURPOSE

Intravenous anesthetics have excellent analgesic activity without inducing the side effect in the respiratory system. The aim and objective of the current experimental study was to access the neuroprotective effect of sevoflurane against isoflurane induced cognitive dysfunction in rats.

METHODS

Isoflurane was used for induction the neurodysfunction in the rats, and rats received the oral administration of sevoflurane (2.5, 5 and 10 mg/kg). Morris water test was carried out for the estimation of cognitive function. Neurochemical parameters, antioxidant parameters and pro-inflammatory cytokines were also estimated.

RESULTS

Sevoflurane significantly (P < 0.001) altered the neurochemical parameters such as anti-choline acetyltransferase, acetylcholine esterase, acetylcholine, protein carbonyl, choline brain-derived neurotrophic factor, and amyloid β; antioxidant parameters such as glutathione, superoxide dismutase, and malondialdehyde; pro-inflammatory cytokines include interleukin (IL-2, IL-10, IL-4, IL-6, IL-10, IL-1β), and tumor necrosis factor-α. Sevoflurane significantly reduced the activity of caspase-3.

CONCLUSIONS

Sevoflurane exhibited the neuroprotection against the cognitive dysfunction in rats via anti-inflammatory and antioxidant mechanism.

Improvement Effect of Mitotherapy on the Cognitive Ability of Alzheimer's Disease through NAD+/SIRT1-Mediated Autophagy

To date, Alzheimer's disease (AD) has grown to be a predominant health challenge that disturbs the elderly population. Studies have shown that mitochondrial dysfunction is one of the most significant features of AD. Transplantation therapy of healthy mitochondria (mitotherapy), as a novel therapeutic strategy to restore mitochondrial function, is proposed to treat the mitochondria-associated disease. Also, the molecular mechanism of mitotherapy remains unclear. Here, we applied the mitotherapy in AD model mice induced by amyloid-β (Aβ) plaque deposition and suggested that autophagy would be an important mechanism of the mitotherapy. After the healthy mitochondria entered the defective neuronal cells damaged by the misfolded Aβ protein, autophagy was activated through the NAD+-dependent deacetylase sirtuin 1 (SIRT1) signal. The damaged mitochondria and Aβ protein were eliminated by autophagy, which could also decrease the content of radical oxygen species (ROS). Moreover, the levels of brain-derived neurotrophic factor (BDNF) and extracellular-regulated protein kinases (ERK) phosphorylation increased after mitotherapy, which would be beneficial to repair neuronal function. As a result, the cognitive ability of AD animals was ameliorated in a water maze test after the healthy mitochondria were administrated to the mice. The study indicated that mitotherapy would be an effective approach to AD treatment through the mechanism of autophagy activation.

Anxiety and Alzheimer's disease pathogenesis: focus on 5-HT and CRF systems in 3xTg-AD and TgF344-AD animal models

Dementia remains one of the leading causes of morbidity and mortality in older adults. Alzheimer's disease (AD) is the most common type of dementia, affecting over 55 million people worldwide. AD is characterized by distinct neurobiological changes, including amyloid-beta protein deposits and tau neurofibrillary tangles, which cause cognitive decline and subsequent behavioral changes, such as distress, insomnia, depression, and anxiety. Recent literature suggests a strong connection between stress systems and AD progression. This presents a promising direction for future AD research. In this review, two systems involved in regulating stress and AD pathogenesis will be highlighted: serotonin (5-HT) and corticotropin releasing factor (CRF). Throughout the review, we summarize critical findings in the field while discussing common limitations with two animal models (3xTg-AD and TgF344-AD), novel pharmacotherapies, and potential early-intervention treatment options. We conclude by highlighting promising future pharmacotherapies and translational animal models of AD and anxiety.

Assessing Drug Administration Techniques in Zebrafish Models of Neurological Disease

Neurological diseases, including neurodegenerative and neurodevelopmental disorders, affect nearly one in six of the world's population. The burden of the resulting deaths and disability is set to rise during the next few decades as a consequence of an aging population. To address this, zebrafish have become increasingly prominent as a model for studying human neurological diseases and exploring potential therapies. Zebrafish offer numerous benefits, such as genetic homology and brain similarities, complementing traditional mammalian models and serving as a valuable tool for genetic screening and drug discovery. In this comprehensive review, we highlight various drug delivery techniques and systems employed for therapeutic interventions of neurological diseases in zebrafish, and evaluate their suitability. We also discuss the challenges encountered during this process and present potential advancements in innovative techniques.

Correlation of serum complement factor 5a level with inflammatory response and cognitive function in patients with Alzheimer's disease of different severity

BACKGROUND

Alzheimer's disease (AD) is a common cause of dementia. Serum complement factor 5a (C5a) is exceedingly implicated in AD. We explored the role of C5a levels in AD patients of different severity.

METHODS

Mild, moderate, and severe AD patients, and healthy controls were included. C5a and pro-inflammatory factor (TNF-α, IL-1β, IL-6, CRP) levels were assessed by ELISA, and cognitive function was evaluated by Mini-Mental state examination (MMSE) score. The correlations between C5a, inflammatory factor levels, MMSE score, and plasma Aβ42/Aβ40 ratio were analyzed by Pearson tests. Independent risk factors for AD aggravation were assessed by logistic multivariate regression analysis. According to the cut-off value of receiver operating characteristic (ROC) curve analysis of C5a level, AD patients were assigned into low/high expression groups, and severe AD incidence was compared. Severe AD cumulative incidence was analyzed by Kaplan-Meier curve.

RESULTS

Serum C5a, TNF-α, IL-1β, IL-6 and CRP levels were raised, and MMSE score was lowered in AD. Serum C5a, TNF-α, IL-1β, IL-6 and CRP levels in severe AD patients were higher than those in mild/moderate AD patients, but there were no significant differences in these cytokines between moderate and mild AD groups. The MMSE score of severe AD patients was lower than that of mild/moderate AD patients. Serum C5a level was positively correlated with serum TNF-α, IL-1β, IL-6, and CRP levels, and negatively correlated with MMSE score, with no obvious correlation with plasma Aβ42/Aβ40 ratio. Serum C5a level was one of the independent risk factors for AD aggravation. The occurrence of severe AD might be related to an increase in serum C5a level.

CONCLUSION

Serum C5a level increased with AD severity, and its expression was positively correlated with serum pro-inflammatory factor levels, and negatively correlated with cognitive function.

Therapeutic Effects of Baicalin on Diseases Related to Gut-Brain Axis Dysfunctions

The gut-brain axis is an active area of research. Several representative diseases, including central nervous system disorders (Alzheimer's disease, Parkinson's disease, and depression), metabolic disorders (obesity-related diseases), and intestinal disorders (inflammatory bowel disease and dysbiosis), are associated with the dysfunctional gut-brain axis. Baicalin, a bioactive flavonoid extracted from Scutellaria baicalensis, is reported to exert various pharmacological effects. This narrative review summarizes the molecular mechanisms and potential targets of baicalin in disorders of the gut-brain axis. Baicalin protects the central nervous system through anti-neuroinflammatory and anti-neuronal apoptotic effects, suppresses obesity through anti-inflammatory and antioxidant effects, and alleviates intestinal disorders through regulatory effects on intestinal microorganisms and short-chain fatty acid production. The bioactivities of baicalin are mediated through the gut-brain axis. This review comprehensively summarizes the regulatory role of baicalin in gut-brain axis disorders, laying a foundation for future research, although further confirmatory basic research is required.

Kaempferol, a potential neuroprotective agent in neurodegenerative diseases: From chemistry to medicine

Neurodegenerative diseases (NDDs) encompass a range of conditions that involve progressive deterioration and dysfunction of the nervous system. Some of the common NDDs include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). Although significant progress has been made in understanding the pathological mechanisms of NDDs in recent years, the development of targeted and effective drugs for their treatment remains challenging. Kaempferol is a flavonoid whose derivatives include kaempferol-O-rhamnoside, 3-O-β-rutinoside/6-hydroxykaempferol 3,6-di-O-β-d-glucoside, and kaempferide. Emerging studies have suggested that kaempferol and its derivatives possess neuroprotective properties and may have potential therapeutic benefits in NDDs. Here, we aimed to provide a theoretical basis for the use of kaempferol and its derivatives in the clinical treatment of NDDs. We systematically reviewed the literature in the PubMed, Web of Science, and Science Direct databases until June 2022 using the search terms "kaempferol," "kaempferol derivatives," "NDDs," "pharmacokinetics," and "biosynthesis" according to the reporting items for systematic review (PRISMA) standard. Based on combined results of in vivo and in vitro studies, we summarize the basic mechanisms and targets of kaempferol and its derivatives in the management of AD, PD, HD, and ALS. Kaempferol and its derivatives exert a neuroprotective role mainly by preventing the deposition of amyloid fibrils (such as Aβ, tau, and α-synuclein), inhibiting microglia activation, reducing the release of inflammatory factors, restoring the mitochondrial membrane to prevent oxidative stress, protecting the blood-brain barrier, and inhibiting specific enzyme activities (such as cholinesterase). Kaempferol and its derivatives are promising natural neuroprotective agents. By determining their pharmacological mechanism, kaempferol and its derivatives may be new candidate drugs for the treatment of NDDs.

Constituent isoflavones of Puerariae radix as a potential neuroprotector in cognitive impairment: Evidence from preclinical studies

With the increasing aging population worldwide, the incidence of senile cognitive impairment (CI) is increasing, posing a serious threat to the health of elderly persons. Despite developing new drugs aimed at improving CI, progress in this regard has been insufficient. Natural preparations derived from plants have become an unparalleled resource for developing new drugs. Puerariae radix (PR) has a long history as Chinese herbal medicine. PR is rich in various chemical components such as isoflavones, triterpenes, and saponins. The isoflavones (puerarin, daidzein, formononetin, and genistein) exhibit potential therapeutic effects on CI through multiple mechanisms. Relevant literature was organized from major scientific databases such as PubMed, Elsevier, SpringerLink, ScienceDirect, and Web of Science. Using "Puerariae radix," "Pueraria lobata," "isoflavones," "puerarin," "antioxidant," "daidzein," "formononetin," "genistein," "Alzheimer"s disease," and "vascular cognitive impairment" as keywords, the relevant literature was extracted from the databases mentioned above. We found that isoflavones from PR have neuroprotective effects on multiple models of CI via multiple targets and mechanisms. These isoflavones prevent Aβ aggregation, inhibit tau hyperphosphorylation, increase cholinergic neurotransmitter levels, reduce neuroinflammation and oxidative stress, improve synaptic plasticity, promote nerve regeneration, and prevent apoptosis. PR has been used as traditional Chinese herbal medicine for a long time, and its constituent isoflavones exert significant therapeutic effects on CI through various neuroprotective mechanisms. This review will contribute to the future development of isoflavones present in PR as novel drug candidates for the clinical treatment of CI.

SIRT2 Inhibition Rescues Neurodegenerative Pathology but Increases Systemic Inflammation in a Transgenic Mouse Model of Alzheimer's Disease

Sirtuin 2 (SIRT2) has been proposed to have a central role on aging, inflammation, cancer and neurodegenerative diseases; however, its specific function remains controversial. Recent studies propose SIRT2 pharmacological inhibition as a therapeutic strategy for several neurodegenerative diseases including Alzheimer's disease (AD). Surprisingly, none of these published studies regarding the potential interest of SIRT2 inhibition has assessed the peripheral adverse side consequences of this treatment. In this study, we demonstrate that the specific SIRT2 inhibitor, the compound 33i, does not exhibit genotoxic or mutagenic properties. Moreover, pharmacological treatment with 33i, improved cognitive dysfunction and long-term potentiation, reducing amyloid pathology and neuroinflammation in the APP/PS1 AD mouse model. However, this treatment increased peripheral levels of the inflammatory cytokines IL-1β, TNF, IL-6 and MCP-1. Accordingly, peripheral SIRT2 inhibition with the blood brain barrier impermeable compound AGK-2, worsened the cognitive capacities and increased systemic inflammation. The analysis of human samples revealed that SIRT2 is increased in the brain but not in the serum of AD patients. These results suggest that, although SIRT2 pharmacological inhibition may have beneficial consequences in neurodegenerative diseases, its pharmacological inhibition at the periphery would not be recommended and the systemic adverse side effects should be considered. This information is essential to maximize the therapeutic potential of SIRT2 inhibition not only for AD but also for other neurodegenerative diseases.

No genetic causal association between dental caries and Alzheimer's disease: a bidirectional two-sample Mendelian randomization analysis

Background

An increasing number of observational studies have suggested an association between dental caries and Alzheimer's disease (AD). The association between dental caries and Alzheimer's disease may be mediated by confounders or reverse causality. In this study, we conducted bidirectional two-sample Mendelian randomization (MR) to estimate the bidirectional causality between dental caries and AD.

Materials and Methods

Genome-wide association study (GWAS) summary statistics of dental caries were extracted from a published meta-analysis which included a total of 487,823 participants. GWAS datasets of AD and AD onset age were obtained from the FinnGen bank. A bidirectional two-sample analysis was performed to explore the causality between dental caries and AD.

Results

For the dental caries-AD causality estimation, there was no significant association between dental caries and AD, neither with the AD GWASs from the FinnGen database (OR: 1.041, p = 0.874) nor with those from the International Genomics of Alzheimer's Project (OR: 1.162, p = 0.409). In addition, the genetic susceptibility to dental caries was not related to the onset age of AD. No causality existed between dental caries and early-onset AD (OR: 0.515, p = 0.302) or late-onset AD (OR: 1.329, p = 0.347). For the AD-dental caries relationship, no causality was detected by the IVW method (OR: 1.000, p = 0.717). Findings from other MR methods were consistent. The pleiotropy test and sensitivity analysis confirmed the validity of these MR results.

Conclusions

In this bidirectional MR study, robust evidence to support a bidirectional causal effect between dental caries and AD from the GWAS results within large-scale European-descent populations was absent. Having dental caries would not alter the onset age of AD.

Aligning Cross-Species Interactomes for Studying Complex and Chronic Diseases

Neurodegenerative diseases (NDs) are a group of complex disorders characterized by the progressive degeneration and dysfunction of neurons in the central nervous system. NDs encompass many conditions, including Alzheimer's disease and Parkinson's disease. Alzheimer's disease (AD) is a complex disease affecting almost forty million people worldwide. AD is characterized by a progressive decline of cognitive functions related to the loss of connections between nerve cells caused by the prevalence of extracellular Aβ plaques and intracellular neurofibrillary tangles plaques. Parkinson's disease (PD) is a neurodegenerative disorder that primarily affects the movement of an individual. The exact cause of Parkinson's disease is not fully understood, but it is believed to involve a combination of genetic and environmental factors. Some cases of PD are linked to mutations in the LRRK2, PARKIN and other genes, which are associated with familial forms of the disease. Different research studies have applied the Protein Protein Interaction (PPI) networks to understand different aspects of disease progression. For instance, Caenorhabditis elegans is widely used as a model organism for the study of AD due to roughly 38% of its genes having a human ortholog. This study's goal consists of comparing PPI network of C. elegans and human by applying computational techniques, widely used for the analysis of PPI networks between species, such as Local Network Alignment (LNA). For this aim, we used L-HetNetAligner algorithm to build a local alignment among two PPI networks, i.e., C. elegans and human PPI networks associated with AD and PD built-in silicon. The results show that L-HetNetAligner can find local alignments representing functionally related subregions. In conclusion, since local alignment enables the extraction of functionally related modules, the method can be used to study complex disease progression.

Effects of exercise intensity on spatial memory performance and hippocampal synaptic function in SAMP8 mice

Learning and memory impairment is commonly noted in Alzheimer's disease (AD), which is regarded as a progressive synaptic failure disease. Exercise is a nonpharmacological strategy that may help prevent cognitive decline and reduce the risk of AD, which is usually thought to be related to synaptic damage in the hippocampus. However, the effects of exercise intensity on hippocampal memory and synaptic function in AD remain unclear. In this study, senescence-accelerated mouse prone-8 (SAMP8) mice were randomly assigned to the control group (Con), low-intensity exercise group (Low), and moderate-intensity exercise group (Mid). Here, we showed that eight weeks of treadmill exercise beginning in four-month-old mice improved spatial memory and recognition memory in six-month-old SAMP8 mice, while the Con group exhibited impaired spatial memory and recognition memory. Treadmill exercise also improved hippocampal neuron morphology in SAMP8 mice. Furthermore, dendritic spine density and the levels of postsynaptic density protein-95 (PSD95) and Synaptophysin (SYN) increased significantly in the Low and Mid groups as compared with the Con group. We further showed that moderate-intensity exercise (60% of maximum speed) was more efficacious in increasing dendritic spine density、PSD95 and SYN, than low-intensity exercise (40% of maximum speed). In conclusion, the positive effect of treadmill exercise is closely related to exercise intensity, with moderate-intensity exercise showing the most optimal effects.

Effect of different doses of almorexant on learning and memory in 8-month-old APP/PS1 (AD) mice

OBJECTIVE

To explore the effects of different doses of almorexant (an dual orexin receptor antagonist) on learning and memory in Alzheimer's disease (AD) mice.

METHODS

Forty-four APP/PS1 (model of Alzheimer's disease; AD) mice were randomly divided into 4 groups: the control group (CON) and those that received 10mg/kg almorexant (low dose; LOW), 30mg/kg almorexant (medium dose; MED) and 60mg/kg almorexant (high dose; HIGH). During the 28-day intervention period, mice received an intraperitoneal injection at the beginning of the light period (6:00 am). The effects of different doses of almorexant on learning and memory and 24-hour sleep-wake behaviour were assessed by immunohistochemical staining. The above continuous variables are expressed as the mean ± standard deviation (SD), and then univariate regression analysis and generalized estimating equations were performed to compare the groups; these results are expressed as the mean difference (MD) and 95% confidence interval (CI). The statistical software used STATA 17.0 MP.

RESULTS

Forty-one mice completed the experiment (3 died: 2 mice in the HIGH group and 1 mouse in the CON group). Compared with the CON group, the LOW group (MD=6,803s, 95% CI: 4,470 to 9,137s), MED group (MD=14,473s, 95% CI: 12,140 to 16,806s) and the HIGH group (MD=24,505s, 95% CI: 22,052 to 26,959s) had significantly longer sleep durations. The Y maze results showed that LOW group (MD=0.14,95%CI: 0.078 to 0.20) and MED group (MD=0.14,95%CI = 0.074 to 0.20) mice compared to the CON group, and the low-medium dose of Almorexant did not damage the short-term learning and memory performance of APP / PS1 (AD) mice.Compared with the CON, LOW, and MED groups, the HIGH group exhibited a significant decrease in the Aβ plaque-positive area in the cortex (MD= -0.030, 95% CI: -0.035 to -0.025; MD=-0.049, 95% CI: -0.054 to -0.044; and MD=-0.07, 95% CI: -0.076 to -0.066, respectively).

CONCLUSION

The moderate dose of almorexant (30mg/kg) prolonged the sleep duration of APP/PS1 (AD) mice to a greater extent than the low dose (10mg/kg) without altering learning and memory. The MED mice showed a good sleep response and a small residual effect on the next day. High-dose (60mg / kg) almorexant impaired behavioral learning and memory performance in mice.Compared to the CON group and the LOW group, the MED group exhibited improved working memory. Thus, treatment with almorexant may reduce β-amyloid deposition in AD, slowing neurodegeneration. Additional studies are needed to determine the mechanism of action.

Plasminogen decreases Aβ42 and Tau deposition, and shows multi-beneficial effects on Alzheimer's disease in mice and humans

Alzheimer's disease (AD) is the most common neurodegenerative disorder in the world. The aggregation of both amyloid beta (Aβ) peptides extracellularly and Tau proteins intracellularly plays key roles in the pathological consequences of AD, which lead to cholinergic neurodegeneration and eventually death. Currently, there are no effective methods to stop the progression of AD. Using ex vivo, in vivo and clinical approaches, we investigated the functional effects of plasminogen on the widely used FAD, Aβ42 oligomer or Tau intracranial injection-induced AD mouse model and explored its therapeutic effects on patients with AD. The results show that intravenously injected plasminogen rapidly crosses the blood‒brain barrier (BBB); increases plasmin activity in the brain; colocalizes with and effectively promotes the clearance of Aβ42 peptide and Tau protein deposits ex vivo and in vivo; increases the choline acetyltransferase (ChAT) level and decreases the acetylcholinesterase (AChE) activity; and improves the memory functions. Clinically, when GMP-level plasminogen was administered to 6 AD patients for 1-2 weeks, their average scores on the Minimum Mental State Examination (MMSE), which is a standard scoring system used to measure the memory loss and cognitive deficits, were extremely significantly improved by 4.2 ± 2.23 points, e.g., an average increase from 15.5 ± 8.22 before treatment to 19.7 ± 7.09 after treatment. The preclinical study and pilot clinical study suggest that plasminogen is effective in treating AD and may be a promising drug candidate.

Aquaporin-4 in glymphatic system, and its implication for central nervous system disorders

The clearance function is essential for maintaining brain tissue homeostasis, and the glymphatic system is the main pathway for removing brain interstitial solutes. Aquaporin-4 (AQP4) is the most abundantly expressed aquaporin in the central nervous system (CNS) and is an integral component of the glymphatic system. In recent years, many studies have shown that AQP4 affects the morbidity and recovery process of CNS disorders through the glymphatic system, and AQP4 shows notable variability in CNS disorders and is part of the pathogenesis of these diseases. Therefore, there has been considerable interest in AQP4 as a potential and promising target for regulating and improving neurological impairment. This review aims to summarize the pathophysiological role that AQP4 plays in several CNS disorders by affecting the clearance function of the glymphatic system. The findings can contribute to a better understanding of the self-regulatory functions in CNS disorders that AQP4 were involved in and provide new therapeutic alternatives for incurable debilitating neurodegenerative disorders of CNS in the future.

Exploration and Clinical Verification of the Blood Co-Expression Genes of Type 2 Diabetes Mellitus and Mild Cognitive Dysfunction in the Elderly

With the development of society, the incidence of dementia and type 2 diabetes (T2DM) in the elderly has been increasing. Although the correlation between T2DM and mild cognitive impairment (MCI) has been confirmed in the previous literature, the interaction mechanism remains to be clarified. To explore the co-pathogenic genes in the blood of MCI and T2DM patients, clarify the correlation between T2DM and MCI, achieve the purpose of early disease prediction, and provide new ideas for the prevention and treatment of dementia. We downloaded T2DM and MCI microarray data from GEO databases and identified the differentially expressed genes associated with MCI and T2DM. We obtained co-expressed genes by intersecting differentially expressed genes. Then, we performed GO and KEGG enrichment analysis of co-DEGs. Next, we constructed the PPI network and found the hub genes in the network. By constructing the ROC curve of hub genes, the most valuable genes for diagnosis were obtained. Finally, the correlation between MCI and T2DM was clinically verified by means of a current situation investigation, and the hub gene was verified by qRT-PCR. A total of 214 co-DEGs were selected, 28 co-DEGs were up-regulated, and 90 co-DEGs were down-regulated. Functional enrichment analysis showed that co-DEGs were mainly enriched in metabolic diseases and some signaling pathways. The construction of the PPI network identified the hub genes in MCI and T2DM co-expression genes. We identified nine hub genes of co-DEGs, namely LNX2, BIRC6, ANKRD46, IRS1, TGFB1, APOA1, PSEN1, NPY, and ALDH2. Logistic regression analysis and person correlation analysis showed that T2DM was correlated with MCI, and T2DM increased the risk of cognitive impairment. The qRT-PCR results showed that the expressions of LNX2, BIRC6, ANKRD46, TGFB1, PSEN1, and ALDH2 were consistent with the results of bioinformatic analysis. This study screened the co-expressed genes of MCI and T2DM, which may provide new therapeutic targets for the diagnosis and treatment of diseases.

The Potential Use of Honey as a Neuroprotective Agent for the Management of Neurodegenerative Diseases

As the global population ages, there is an increasing research on managing neurodegenerative diseases that mainly affect the elderly. Honey is one of the natural products and functional foods widely studied for its neuroprotective properties. This review investigates honey's effectiveness as a neuroprotective agent through in vitro, in vivo, and clinical research. The articles were browsed from three databases (PubMed, ScienceDirect, and Scopus) between the years of 2012 and 2022 using the keywords "honey" crossed with "neurodegenerative". Out of the 16 articles, six in vitro, eight in vivo, one combination study, and one clinical intervention were compiled. Among the various types of honey studied, the Tualang and Thyme honey exhibited the highest antioxidant, anti-inflammatory, and anticholinesterase activity, leading to the prevention and management of multiple neurodegenerative diseases such as Alzheimer's disease. The neuroprotective properties of honey are primarily attributed to its high polyphenol content, with quercetin and gallic acid being the most prominent. This review compiled considerable evidence of the anti-neurodegenerative properties of honey presented by in vitro and in vivo studies. However, more clinical intervention studies are required to support these findings further.

The Role of the Transcription Factor Nrf2 in Alzheimer’s Disease: Therapeutic Opportunities

Alzheimer’s disease (AD) is a common neurodegenerative disorder that affects the elderly. One of the key features of AD is the accumulation of reactive oxygen species (ROS), which leads to an overall increase in oxidative damage. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a master regulator of the antioxidant response in cells. Under low ROS levels, Nrf2 is kept in the cytoplasm. However, an increase in ROS production leads to a translocation of Nrf2 into the nucleus, where it activates the transcription of several genes involved in the cells’ antioxidant response. Additionally, Nrf2 activation increases autophagy function. However, in AD, the accumulation of Aβ and tau reduces Nrf2 levels, decreasing the antioxidant response. The reduced Nrf2 levels contribute to the further accumulation of Aβ and tau by impairing their autophagy-mediated turnover. In this review, we discuss the overwhelming evidence indicating that genetic or pharmacological activation of Nrf2 is as a potential approach to mitigate AD pathology.

Study on Absorption, Distribution and Excretion of a New Candidate Compound XYY-CP1106 against Alzheimer's Disease in Rats by LC-MS/MS

XYY-CP1106, a candidate compound synthesized from a hybrid of hydroxypyridinone and coumarin, has been shown to be remarkably effective in treating Alzheimer's disease. A simple, rapid and accurate high-performance liquid chromatography coupled with the triple quadrupole mass spectrometer (LC-MS/MS) method was established in this study to elucidate the pharmacokinetics of XYY-CP1106 after oral and intravenous administration in rats. XYY-CP1106 was shown to be rapidly absorbed into the blood (T_max, 0.57-0.93 h) and then eliminated slowly (T_1/2, 8.26-10.06 h). Oral bioavailability of XYY-CP1106 was (10.70 ± 1.72)%. XYY-CP1106 could pass through the blood-brain barrier with a high content of (500.52 ± 260.12) ng/g at 2 h in brain tissue. The excretion results showed that XYY-CP1106 was mainly excreted through feces, with an average total excretion rate of (31.14 ± 0.05)% in 72 h. In conclusion, the absorption, distribution and excretion of XYY-CP1106 in rats provided a theoretical basis for subsequent preclinical studies.

Shared peripheral blood biomarkers for Alzheimer’s disease, major depressive disorder, and type 2 diabetes and cognitive risk factor analysis

Background

Alzheimer's disease (AD), type 2 diabetes mellitus (T2DM), and Major Depressive Disorder (MDD) have a higher incidence rate in modern society. Although increasing evidence supports close associations between the three, the mechanisms underlying their interrelationships remain elucidated.

Objective

The primary purpose is to explore the shared pathogenesis and the potential peripheral blood biomarkers for AD, MDD, and T2DM.

Methods

We downloaded the microarray data of AD, MDD, and T2DM from the Gene Expression Omnibus database and constructed co-expression networks by Weighted Gene Co-Expression Network Analysis to identify differentially expressed genes. We took the intersection of differentially expressed genes to obtain co-DEGs. Then, we performed GO and KEGG enrichment analysis on the common genes in the AD, MDD, and T2DM-related modules. Next, we utilized the STRING database to find the hub genes in the protein-protein interaction network. ROC curves were constructed for co-DEGs to obtain the most diagnostic valuable genes and to make drug predictions against the target genes. Finally, we conducted a present condition survey to verify the correlation between T2DM, MDD and AD.

Results

Our findings indicated 127 diff co-DEGs, 19 upregulated co-DEGs, and 25 down-regulated co-DEGs. Functional enrichment analysis showed co-DEGs were mainly enriched in signaling pathways such as metabolic diseases and some neurodegeneration. Protein-protein interaction network construction identified hub genes in AD, MDD and T2DM shared genes. We identified seven hub genes of co-DEGs, namely, SMC4, CDC27, HNF1A, RHOD, CUX1, PDLIM5, and TTR. The current survey results suggest a correlation between T2DM, MDD and dementia. Moreover, logistic regression analysis showed that T2DM and depression increased the risk of dementia.

Conclusion

Our work identified common pathogenesis of AD, T2DM, and MDD. These shared pathways might provide novel ideas for further mechanistic studies and hub genes that may serve as novel therapeutic targets for diagnosing and treating.

Cornuside, by regulating the AGEs-RAGE-IκBα-ERK1/2 signaling pathway, ameliorates cognitive impairment associated with brain aging

Anti-Alzheimer's disease (AD) drugs can only change the symptoms of cognitive impairment in a short time but cannot prevent or completely cure AD. Thus, a more effective drug is urgently needed. Cornuside is extracted from Corni Fructus, a traditional Chinese medicine that plays an important role in treating dementia and other age-related diseases. Thus, the study aimed to explore the effects and mechanisms of Cornuside on the D-galactose (D-Gal) induced aging mice accompanied by cognitive decline. Initially, we found that Cornuside improved the learning and memory abilities of D-Gal-treated mice in behavioral experiments. Pharmacological experiments indicated that Cornuside acted on anti-oxidant and anti-inflammatory effects. Cornuside also reversed acetylcholin esterase (AChE) activity. Meanwhile, pathology tests showed that Cornuside had a protective effect on neuron damage. Cornuside increased the expression of brain-derived neurotrophic factor (BDNF), and down-regulated the expression of receptor for advanced glycosylation end products (RAGE), ionized calcium binding adapter molecule 1 (Iba1), and glial fibrillary acidic protein (GFAP) respectively. Further studies claimed that Cornuside had important effects on the expression of IκBα and extracellular signal-regulated kinases 1/2 (ERK1/2). These effects might be achieved through regulating the AGEs-RAGE-IκBα-ERK1/2 signaling pathway, among which, ERK1/2 might be the key protein. The study provides direct preclinical evidence for the research of Cornuside, which may become an excellent candidate drug for the treatment of aging-related AD.

Effect of a dual orexin receptor antagonist on Alzheimer's disease: Sleep disorders and cognition

Orexin is a neuropeptide produced by the lateral hypothalamus that plays an important role in regulating the sleep-wake cycle. The overexpression of the orexinergic system may be related to the pathology of sleep/wakefulness disorders in Alzheimer's disease (AD). In AD patients, the increase in cerebrospinal fluid orexin levels is associated with parallel sleep deterioration. Dual orexin receptor antagonist (DORA) can not only treat the sleep-wakefulness disorder of AD but also improve the performance of patients with cognitive behavior disorder. It is critical to clarify the role of the orexin system in AD, study its relationship with cognitive decline in AD, and evaluate the safety and efficacy of DORA.

Electroacupuncture Improves Blood-Brain Barrier and Hippocampal Neuroinflammation in SAMP8 Mice by Inhibiting HMGB1/TLR4 and RAGE/NADPH Signaling Pathways

OBJECTIVE

To investigate the molecular mechanisms underlying the beneficial effect of electroacupuncture (EA) in experimental models of Alzheimer's disease (AD) in vivo.

METHODS

Senescence-accelerated mouse prone 8 (SAMP8) mice were used as AD models and received EA at Yingxiang (LI 20, bilateral) and Yintang (GV 29) points for 20 days. For certain experiments, SAMP8 mice were injected intravenously with human fibrin (2 mg). The Morris water maze test was used to assess cognitive and memory abilities. The changes of tight junctions of blood-brain barrier (BBB) in mice were observed by transmission electron microscope. The expressions of fibrin, amyloid- β (Aβ), and ionized calcium-binding adapter molecule 1 (IBa-1) in mouse hippocampus (CA1/CA3) were detected by reverse transcription-quantitative polymerase chain reaction (qRT-PCR), Western blot or immunohistochemical staining. The expression of fibrin in mouse plasma was detected by enzyme-linked immunosorbent assay. The expressions of tight junction proteins zonula occludens-1 and claudin-5 in hippocampus were detected by qRT-PCR and immunofluorescence staining. Apoptosis of hippocampal neurons was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining.

RESULTS

Fibrin was time-dependently deposited in the hippocampus of SAMP8 mice and this was inhibited by EA treatment (P<0.05 or P<0.01). Furthermore, EA treatment suppressed the accumulation of Aβ in the hippocampus of SAMP8 mice (P<0.01), which was reversed by fibrin injection (P<0.05 or P<0.01). EA improved SAMP8 mice cognitive impairment and BBB permeability (P<0.05 or P<0.01). Moreover, EA decreased reactive oxygen species levels and neuroinflammation in the hippocampus of SAMP8 mice, which was reversed by fibrin injection (P<0.05 or P<0.01). Mechanistically, EA inhibited the promoting effect of fibrin on the high mobility group box protein 1 (HMGB1)/toll-like receptor 4 (TLR4) and receptor for advanced glycation end products (RAGE)/nicotinamide adenine dinucleotide phosphate (NADPH) signaling pathways (P<0.01).

CONCLUSION

EA may potentially improve cognitive impairment in AD via inhibition of fibrin/A β deposition and deactivation of the HMGB1/TLR4 and RAGE/NADPH signaling pathways.

Correlation of blood-brain barrier leakage with cerebral small vessel disease including cerebral microbleeds in Alzheimer's disease

Background

Blood-brain barrier (BBB) damage is considered an important part of Alzheimer's disease (AD) progression, and cerebral small-vessel disease (CSVD) is commonly associated with AD. However, the relationship between BBB damage, small cerebrovascular lesions, especially cerebral microbleeds (CMBs), and amyloid and tau biomarkers remains controversial. Therefore, our study aimed to further investigate their association in our cohort of patients with AD.

Methods

A total of 139 individuals were divided into probable AD (¹⁸F-florbetapir PET positive, n = 101) and control group (cognitively normal, n = 38). The levels of cerebrospinal fluid (CSF) and plasma t-tau, p-tau181, Aβ40, Aβ42, and albumin were measured using corresponding commercial assay kits, and the CSF/plasma albumin ratio (Qalb), an indicator of BBB dysfunction, was calculated. CSVD burden and the number of CMBs were defined using magnetic resonance imaging.

Results

Patients with AD had higher Qalb (p = 0.0024), higher numbers of CMBs (p = 0.03), and greater CSVD burden (p < 0.0001). In the AD group, CMBs and CSVD correlated with a higher Qalb (p = 0.03), and the numbers of CMBs negatively correlated with CSF Aβ42 (p = 0.02).

Conclusion

Blood-brain barrier damage was accompanied by a more severe burden of CSVD, including CMB, in patients with AD.

S1PR2 Regulates Autophagy Through the AKT/mTOR Pathway to Promote Pathological Damage in Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is a fatal and debilitating neurodegenerative disease. Sphingosine-1-phosphate receptor 2 (S1PR2), one of the receptors of S1P, is a key regulatory factor for various diseases.

OBJECTIVE

This study aimed to explore the role and possible mechanism of S1PR2 in AD.

METHODS

S1PR2 expression in the AD mice was detected, and after intervening S1PR2 expression with sh-S1PR2 in AD mice, the behavioral changes, pathological lesions of the hippocampus, autophagy level, and AKT/mTOR pathway activation were analyzed. Furthermore, SH-SY5Y cells were induced by Aβ25-35 to construct an AD cell model, and the effects of sh-S1PR2 on proliferation, apoptosis, autophagy, and AKT/mTOR pathway of AD cells were investigated. In addition, the effects of pathway inhibitor rapamycin on model cells were further analyzed.

RESULTS

The expression of S1PR2 was significantly increased in AD mice, the sh-S1PR2 significantly improved behavioral dysfunction, alleviated pathological injury of the hippocampus, increased the number of neurons, and inhibited Aβ production and p-tau expression, showing a positive effect on the AD pathology. In addition, silencing of S1PR2 expression significantly promoted the autophagy level and inhibited the activation of the AKT/mTOR pathway in AD model mice. In vitro experiments further confirmed that sh-S1PR2 promoted cell proliferation, inhibited apoptosis, relieved cytopathology, promoted autophagy, and inhibited the activation of the AKT/mTOR pathway in the cell model. The use of rapamycin further confirmed the role of AKT/mTOR pathway-mediated autophagy in the regulation of AD by S1PR2.

CONCLUSION

S1PR2 promoted AD pathogenesis by inhibiting autophagy through the activation of AKT/mTOR pathway.

Leptin ameliorates Aβ1-42-induced Alzheimer's disease by suppressing inflammation via activating p-Akt signaling pathway

Background

Alzheimer's disease (AD) is characterized by progressive neuronal loss, cognitive disorder, and memory decline. Leptin has been reported to have a neuroprotective effect on neurodegenerative diseases.

Objective

Our aim was to investigate whether intraperitoneal injection of leptin has a neuroprotective effect and to explore its underlying mechanisms in the AD mouse model.

Methods

Aβ1-42 was injected into male C57BL/6J mice to construct an AD mouse model, and leptin was injected intraperitoneally to cure AD. The Morris water maze test was used to investigate spatial learning ability. Neuronal loss was tested by tyrosine hydroxylase expression in the hippocampus, and terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling assay was applied to detect neuronal apoptosis. Pro-inflammatory cytokine levels were monitored by RT-PCR and western blotting was selected to explore which signaling pathway leptin acted on.

Results

Leptin ameliorated spatial learning impairment, restored neuronal loss and apoptosis, and inhibited pro-inflammatory cytokine expression by activating the p-Akt signaling pathway in Aβ1-42-induced AD mice.

Conclusion

Leptin ameliorates Aβ1-42-induced AD by suppressing inflammation via activating the p-Akt signaling pathway.

Inhibition of circ_0004381 improves cognitive function via miR-647/PSEN1 axis in an Alzheimer disease mouse model

Circ_0004381 promotes neuronal damage in Parkinson disease, but its role in Alzheimer disease (AD) is unreported. The goal of this study was to investigate the role and potential mechanisms of circ_0004381 effects in AD models. Primary hippocampal neurons were treated with amyloid-β (Aβ1-42) to construct AD cell models. We found that circ_0004381 was upregulated in Aβ1-42-treated hippocampal neurons. Knockdown of circ_0004381 attenuated Aβ1-42-induced apoptosis, oxidative stress, and mitochondrial dysfunction in hippocampal neurons. Next, we induced microglia activation with lipopolysaccharide (LPS). The results of flow cytometry experiments showed that knockdown of circ_0004381 promoted microglial M2-type polarization and knockdown of circ_0004381 inhibited the production of inflammatory factors by microglia. Furthermore, knockdown of circ_0004381 improved cognitive function of male APPswe/PS1dE9 transgenic mice. Mechanistically, circ_0004381 regulated presenilin-1 (PSEN1) expression by absorbing miR-647. MiR-647 inhibition attenuated the effects of circ_0004381 knockdown. In conclusion, knockdown of circ_0004381 attenuated hippocampal neuronal damage and promoted microglia M2-type polarization through the miR-647/PSEN1 axis, ultimately improving cognitive function in AD model mice.

Sleep deficiency promotes Alzheimer's disease development and progression

Sleep disorders are a common health problem in modern society. Long-term sleep deficiency increases the risk for Alzheimer's disease. However, the exact mechanisms by which sleep deficiency affects Alzheimer's disease remain unclear. Therefore, we reviewed the relevant studies and investigated the role of sleep deprivation in Alzheimer's disease pathogenesis. Sleep deficiency was found to be associated with oxidative stress, β-amyloid protein deposition, tau hyperphosphorylation, and neuroinflammation, which are known to increase the risk for Alzheimer's disease. In addition, insufficient sleep also increases glucocorticoid levels, decreases brain-derived neurotrophic factor levels, and reduces the number of synapses in the central nervous system. These factors also promote Alzheimer's disease development and progression. The present study showed that a growing body of evidence supports an association between sleep disturbances and Alzheimer's disease. It discusses the role of sleep insufficiency in Alzheimer's disease pathogenesis, which may provide a theoretical basis for effective treatment and prevention strategies.

Zunyimycin C enhances immunity and improves cognitive impairment and its mechanism

This study aimed to explore the efficacy of zunyimycin C in the immunological enhancement of hypoimmune mice and improvement of cognitive impairment in a mice model of Alzheimer's disease (AD). Zunyimycin C was administered intranasally to interfere with AD mouse models or gavage to hypoimmune animals. Results of the Morris water maze (MWM) showed that zunyimycin may improve the learning and memory abilities of the AD mice model. The results of differential expression analysis of mRNA levels of inflammatory factors and pathways in brain tissues of the AD mouse model suggested that differential expression was more obvious under Zun-Int L. Western blot revealed that the relative expression of glial fibrillary acidic protein in the brain tissue of the AD mouse model in the Zun-Pre group was significantly higher than that in the other groups, and the difference was statistically significant. The relative expression of interleukin (IL)-6 protein in the brain tissue of mice in the low-dose intervention group was significantly lower than that in the other groups, and the difference was statistically significant. As for hypoimmune animals, short chain fatty acids (SCFAs) assay and intestinal flora assay results showed that zunyimycin C may change intestinal flora diversity and SCFA biosynthesis. The prophylactic administration of zunyimycin C could not inhibit acute neuroinflammation in AD mice. Zunyimycin C may participate in the immune response by activating the Ras-Raf-MEK-ERK signaling pathway to stimulate microglia to produce more inflammatory factors. Zunyimycin C may inhibit autophagy by activating the PI3K-AKT-mTOR signaling pathway, promote cell survival, mediate neuroprotective effects of reactive microglia and reactive astrocytes, and reduce IL-1β in brain tissue and IL-6 secretion, thereby attenuating neuroinflammation in AD mice and achieving the effect of improving learning and memory impairment. Zunyimycin C may play a role in immunological enhancement by changing intestinal flora diversity and SCFAs.

A Review of the Recent Advances in Alzheimer's Disease Research and the Utilization of Network Biology Approaches for Prioritizing Diagnostics and Therapeutics

Alzheimer's disease (AD) is a polygenic multifactorial neurodegenerative disease that, after decades of research and development, is still without a cure. There are some symptomatic treatments to manage the psychological symptoms but none of these drugs can halt disease progression. Additionally, over the last few years, many anti-AD drugs failed in late stages of clinical trials and many hypotheses surfaced to explain these failures, including the lack of clear understanding of disease pathways and processes. Recently, different epigenetic factors have been implicated in AD pathogenesis; thus, they could serve as promising AD diagnostic biomarkers. Additionally, network biology approaches have been suggested as effective tools to study AD on the systems level and discover multi-target-directed ligands as novel treatments for AD. Herein, we provide a comprehensive review on Alzheimer's disease pathophysiology to provide a better understanding of disease pathogenesis hypotheses and decipher the role of genetic and epigenetic factors in disease development and progression. We also provide an overview of disease biomarkers and drug targets and suggest network biology approaches as new tools for identifying novel biomarkers and drugs. We also posit that the application of machine learning and artificial intelligence to mining Alzheimer's disease multi-omics data will facilitate drug and biomarker discovery efforts and lead to effective individualized anti-Alzheimer treatments.

Lycopene: Sojourn from kitchen to an effective therapy in Alzheimer's disease

Reports on a significant positive correlation between consumption of carotenoid-rich food and prevention of Alzheimer's disease (AD) led to the investigation of carotenoids for the treatment and prevention of AD. More than 1100 types of carotenoids are found naturally, out of which only around 50 are absorbed and metabolized in human body. Lycopene is one of the most commonly ingested members of fat-soluble carotenoid family that gives vegetables and fruits their red, yellow, or orange color. Lycopene has established itself as a promising therapy for AD owing to its neuroprotective activities, including antioxidant, anti-inflammatory, and antiamyloidogenic properties. In this review, we highlight the various in vitro and preclinical studies demonstrating the neuroprotective effect of lycopene. Also, some epidemiological and interventional studies investigating the protective effect of lycopene in AD have been discussed. Diving deeper, we also discuss various significant mechanisms, through which lycopene exerts its remissive effects in AD. Finally, to overcome the issue of poor chemical stability and bioavailability of lycopene, some of the novel delivery systems developed for lycopene have also been briefly highlighted.

Cerebrospinal fluid neurofilament light chain differentiates primary psychiatric disorders from rapidly progressive, Alzheimer's disease and frontotemporal disorders in clinical settings

INTRODUCTION

Many patients with cognitive and neuropsychiatric symptoms face diagnostic delay and misdiagnosis. We investigated whether cerebrospinal fluid (CSF) neurofilament light (NfL) and total-tau (t-tau) could assist in the clinical scenario of differentiating neurodegenerative (ND) from psychiatric disorders (PSY), and rapidly progressive disorders.

METHODS

Biomarkers were examined in patients from specialist services (ND and PSY) and a national Creutzfeldt-Jakob registry (Creutzfeldt-Jakob disease [CJD] and rapidly progressive dementias/atypically rapid variants of common ND, RapidND).

RESULTS

A total of 498 participants were included: 197 ND, 67 PSY, 161 CJD, 48 RapidND, and 20 controls. NfL was elevated in ND compared to PSY and controls, with highest levels in CJD and RapidND. NfL distinguished ND from PSY with 95%/78% positive/negative predictive value, 92%/87% sensitivity/specificity, 91% accuracy. NfL outperformed t-tau in most real-life clinical diagnostic dilemma scenarios, except distinguishing CJD from RapidND.

DISCUSSION

We demonstrated strong generalizable evidence for the diagnostic utility of CSF NfL in differentiating ND from psychiatric disorders, with high accuracy.

Impaired Dopamine Release and Latent Learning in Alzheimer's Disease Model Zebrafish

Alzheimer's disease (AD) is a progressive, fatal, neurodegenerative disorder for which only treatments of limited efficacy are available. Despite early mentions of dementia in the ancient literature and the first patient diagnosed in 1906, the underlying causes of AD are not well understood. This study examined the possible role of dopamine, a neurotransmitter that is involved in cognitive and motor function, in AD. We treated adult zebrafish (Danio rerio) with okadaic acid (OKA) to model AD and assessed the resulting behavioral and neurochemical changes. We then employed a latent learning paradigm to assess cognitive and motor function followed by neurochemical analysis with fast-scan cyclic voltammetry (FSCV) at carbon fiber microelectrodes to measure the electrically stimulated dopamine release. The behavioral assay showed that OKA treatment caused fish to have lower motivation to reach the goal chamber, resulting in impeded learning and decreased locomotor activity compared to controls. Our voltammetric measurements revealed that the peak dopamine overflow in OKA-treated fish was about one-third of that measured in controls. These findings highlight the profound neurochemical changes that may occur in AD. Furthermore, they demonstrate that applying the latent learning paradigm and FSCV to zebrafish is a promising tool for future neurochemical studies and may be useful for screening drugs for the treatment of AD.

Treadmill Exercise Modulates Intestinal Microbes and Suppresses LPS Displacement to Alleviate Neuroinflammation in the Brains of APP/PS1 Mice

Neuroinflammation occurs throughout the pathogenesis of Alzheimer’s disease (AD). Here, we investigated the effects of treadmill exercise on neuroinflammation in APP/PS1 transgenic AD mice and the potential involvement of microbe–gut–brain axis (MGB) mechanisms based on growing evidence that AD’s pathogenesis is correlated with a deterioration in the function of gut microbiota. APP/PS1 transgenic AD mice were subjected to 12 weeks of treadmill exercise, followed by spatial memory tests. After the behavioral study, the amyloid (Aβ) pathology, gut microbes and metabolites, bacterial lipopolysaccharide (LPS) displacement, and degree of neuroinflammation were analyzed. We found that this strategy of exercise enriched gut microbial diversity and alleviated neuroinflammation in the brain. Notably, exercise led to reductions in pathogenic bacteria such as intestinal Allobaculum, increases in probiotic bacteria such as Akkermansia, increased levels of intestine–brain barrier proteins, and attenuated LPS displacement. These results suggest that prolonged exercise can effectively modulate gut microbes and the intestinal barrier and thereby reduce LPS displacement and ultimately alleviate AD-related neuroinflammation.