Tau and neuroinflammation: What impact for Alzheimer's Disease and Tauopathies?

Recent advances in nanoenzymes for Alzheimer's disease treatment

Alzheimer's disease (AD) remains one of the most challenging neurodegenerative disorders to treat, with oxidative stress playing a significant role in its pathology. Recent advancements in nanoenzymes technology offer a promising approach to mitigate this oxidative damage. Nanoenzymes, with their unique enzyme-mimicking activities, effectively scavenge reactive oxygen species and reduce oxidative stress, thereby providing neuroprotective effects. This review delves into the underlying mechanisms of AD, focusing on oxidative stress and its impact on disease progression. We explore the latest developments in nanoenzymes applications for AD treatment, highlighting their multifunctional capabilities and potential for targeted delivery to amyloid-beta plaques. Despite the exciting prospects, the clinical translation of nanoenzymes faces several challenges, including difficulties in brain targeting, consistent quality production, and ensuring safety and biocompatibility. We discuss these limitations in detail, emphasizing the need for rigorous evaluation and standardized protocols. This paper aims to provide a comprehensive overview of the current state of nanoenzymes research in AD, shedding light on both the opportunities and obstacles in the path towards effective clinical applications.

A novel derivative of evodiamine improves cognitive impairment and synaptic integrity in AD mice

Alzheimer's disease (AD), the major cause of dementia, is a multifactoral progressive neurodegenerative disorder that currently affects over 43 million people worldwide. The interaction betweengenetic and environmental factors decides pathogenesis and pathological development. The chemical drugs designed for clinical applications on AD have not reached the expected preventive effect so far.Here, we obtained a new evodiamine (Evo) derivative, LE-42, which exhibited lower cytotoxicity in SH-SY5Y cells and HepaG2 cells than that of Evo. The LD50 of LE-42 in SH-SY5Y cells and HepaG2 cells was increased by 9 folds and 14 folds than Evo, respectively. The LE-42 also exhibited much more potent effects on anti-oxidation and anti-cytotoxicity of AβOs than Evo. The LE-42 significantly improved the working memory, spatial learning, and memory of the 3×Tg AD mice, and the pharmacodynamic dose of LE-42 on AD mice was increased by 500 folds than that of Evo. LE-42 significantly improved the Tau hyperphosphorylation, a typical pathological feature in 3×Tg AD mice. The LE-42 restored the JAK2/STAT3 pathway's dysfunction and upregulated the expression of GluN1, GluA2, SYN, and PSD95, subsequentially improving the synaptic integrity in 3×Tg mice. The activation of the JAK2/STAT3 axis by LE-42 was a possible mechanism for a therapeutic effect on the AD mice.

Therapeutic potential of plant-derived natural compounds in Alzheimer's disease: Targeting microglia-mediated neuroinflammation

Microglia are resident immune cells of the central nervous system (CNS) with roles in sensing, housekeeping, and defense. Exploring the role of microglia in the occurrence and development of Alzheimer's disease (AD) and the possible therapeutic mechanism of plant-derived natural compounds (PDNCs) that regulate microglia-associated neuroinflammation may potentially help in elucidating the pathogenesis of AD and provide novel insights for its treatment. This review explores the role of abnormal microglial activation and its dominant neuroinflammatory response, as well as the activation of their target receptors and signaling pathways in AD pathogenesis. Additionally, we report an update on the potential pharmacological mechanisms of multiple PDNCs in modulating microglia-associated neuroinflammation in AD treatment. Dysregulated activation of microglial receptors and their downstream pathways impaired immune homeostasis in animal models of AD. Multiple signaling pathways, such as mitogen-activated protein kinase (MAPK), nuclear factor kappa light chain enhancer of activated B cells (NF-κB), and Toll-like receptors, play important roles in microglial activation and can exacerbate microglia-mediated neuroinflammation. PDNCs, such as magnolol, stigmasterol, matrine, naringenin, naringin, and resveratrol, can delay the progression of AD by inhibiting the proinflammatory receptors of microglia, activating its anti-inflammatory receptors, regulating the receptors related to β-amyloid (Aβ) clearance, reversing immune dysregulation, and maintaining the immune homeostasis of microglial downstream pathways. This review summarizes the mechanisms by which microglia cause chronic inflammation in AD and evaluates the beneficial effects of PDNCs on immune regulation in AD by regulating microglial receptors and their downstream pathways.

GSK3-Driven Modulation of Inflammation and Tissue Integrity in the Animal Model

Nowadays, GSK3 is accepted as an enzyme strongly involved in the regulation of inflammation by balancing the pro- and anti-inflammatory responses of cells and organisms, thus influencing the initiation, progression, and resolution of inflammatory processes at multiple levels. Disturbances within its broad functional scope, either intrinsically or extrinsically induced, harbor the risk of profound disruptions to the regular course of the immune response, including the formation of severe inflammation-related diseases. Therefore, this review aims at summarizing and contextualizing the current knowledge derived from animal models to further shape our understanding of GSK3α and β and their roles in the inflammatory process and the occurrence of tissue/organ damage. Following a short recapitulation of structure, function, and regulation of GSK3, we will focus on the lessons learned from GSK3α/β knock-out and knock-in/overexpression models, both conventional and conditional, as well as a variety of (predominantly rodent) disease models reflecting defined pathologic conditions with a significant proportion of inflammation and inflammation-related tissue injury. In summary, the literature suggests that GSK3 acts as a crucial switch driving pro-inflammatory and destructive processes and thus contributes significantly to the pathogenesis of inflammation-associated diseases.

Bibliometric analysis of neuroinflammation and Alzheimer's disease

Background

Alzheimer's disease (AD) is the predominant cause of dementia on a global scale, significantly impacting the health of the elderly population. The pathogenesis of AD is closely linked to neuroinflammation. The present study employs a bibliometric analysis to examine research pertaining to neuroinflammation and AD within the last decade, with the objective of providing a comprehensive overview of the current research profile, hotspots and trends.

Methods

This research conducted a comprehensive review of publications within the Science Citation Index Expanded of the Web of Science Core Collection Database spanning the years 2014 to 2024. Bibliometric analyses were performed using VOSviewer (version 1.6.19) and CiteSpace (version 6.3.R1) software to visualize data on countries, institutions, authors, journals, keywords, and references.

Results

A total of 3,833 publications on neuroinflammation and AD were included from January 2014 to January 2024. Publications were mainly from the United States and China. Zetterberg, Henrik emerged as the author with the highest publication output, while Edison, Paul was identified as the most cited author. The most productive journal was Journal of Alzheimers Disease, and the most co-cited was Journal of Neuroinflammation. Research hotspot focused on microglia, mouse models, oxidative stress, and amyloid-beta through keyword analysis. Additionally, keywords such as blood-brain barrier and tau protein exhibited prolonged citation bursts from 2022 to 2024.

Conclusion

This study provides a comprehensive review of the last 10 years of research on neuroinflammation and AD, including the number and impact of research findings, research hotspots, and future trends. The quantity of publications in this field is increasing, mainly in the United States and China, and there is a need to further strengthen close cooperation with different countries and institutions worldwide. Presently, research hotspots are primarily concentrated on microglia, with a focus on inhibiting their pro-inflammatory responses and promoting their anti-inflammatory functions as a potential direction for future investigations.

Senolytic therapy preserves blood-brain barrier integrity and promotes microglia homeostasis in a tauopathy model

Cellular senescence, characterized by expressing the cell cycle inhibitory proteins, is evident in driving age-related diseases. Senescent cells play a crucial role in the initiation and progression of tau-mediated pathology, suggesting that targeting cell senescence offers a therapeutic potential for treating tauopathy associated diseases. This study focuses on identifying non-invasive biomarkers and validating their responses to a well-characterized senolytic therapy combining dasatinib and quercetin (D+Q), in a widely used tauopathy mouse model, PS19. We employed human-translatable MRI measures, including water extraction with phase-contrast arterial spin tagging (WEPCAST) MRI, T2 relaxation under spin tagging (TRUST), longitudinally assessed brain physiology and high-resolution structural MRI evaluated the brain regional volumes in PS19 mice. Our data reveal increased BBB permeability, decreased oxygen extraction fraction, and brain atrophy in 9-month-old PS19 mice compared to their littermate controls. (D+Q) treatment effectively preserves BBB integrity, rescues cerebral oxygen hypometabolism, attenuates brain atrophy, and alleviates tau hyperphosphorylation in PS19 mice. Mechanistically, D+Q treatment induces a shift of microglia from a disease-associated to a homeostatic state, reducing a senescence-like microglial phenotype marked by increased p16/INK4a. D+Q-treated PS19 mice exhibit enhanced cue-associated cognitive performance in the tracing fear conditioning test compared to the vehicle-treated littermates, implying improved cognitive function by D+Q treatment. Our results pave the way for application of senolytic treatment as well as these noninvasive MRI biomarkers in clinical trials in tauopathy associated neurological disorders.

Neuroprotective effects of Anshen Bunao Syrup on cognitive dysfunction in Alzheimer's disease rat models

Alzheimer's disease (AD) presents a significant challenge due to its prevalence and lack of cure, driving the quest for effective treatments. Anshen Bunao Syrup, a traditional Chinese medicine known for its neuroprotective properties, shows promise in addressing this need. However, understanding its precise mechanisms in AD remains elusive. This study aimed to investigate Anshen Bunao Syrup's therapeutic potential in AD treatment using a scopolamine-induced AD rat model. Assessments included novel-object recognition and Morris water maze tasks to evaluate spatial learning and memory, alongside Nissl staining and ELISA analyses for neuronal damage and biomarker levels. Results demonstrated that Anshen Bunao Syrup effectively mitigated cognitive dysfunction by inhibiting amyloid-β and phosphorylation Tau aggregation, thereby reducing neuronal damage. Metabolomics profiling of rats cortex revealed alterations in key metabolites implicated in tryptophan and fatty acid metabolism pathways, suggesting a role in the therapeutic effects of Anshen Bunao Syrup. Additionally, ELISA and correlation analyses indicated attenuation of oxidative stress and immune response through metabolic remodeling. In conclusion, this study provides compelling evidence for the neuroprotective effects of Anshen Bunao Syrup in AD models, shedding light on its potential as a therapeutic agent for AD prevention and treatment.

All-Trans Retinoic Acid-Induced Cell Surface Heat Shock Protein 90 Mediates Tau Protein Internalization and Degradation in Human Microglia

This study investigates the role of all-trans retinoic acid (ATRA) in modulating the expression of heat shock protein 90 (Hsp90) and its influence on the uptake and degradation of tau proteins in immortalized human microglia cells. We demonstrate that ATRA significantly upregulates Hsp90 expression in a concentration-dependent manner, enhancing both extracellular and intracellular Hsp90 levels. Our results show that ATRA-treated cells exhibit increased tau protein uptake via caveolae/raft-dependent endocytosis pathways. This uptake is mediated by surface Hsp90, as evidenced by the inhibition of tau internalization using an extracellular Hsp90-selective inhibitor. Further, we establish that the exogenously added full-sized monomeric tau proteins bind to Hsp90. The study also reveals that ATRA-enhanced tau uptake is followed by effective degradation through both lysosomal and proteasomal pathways. We observed a significant reduction in intracellular tau levels in ATRA-treated cells, which was reversed by lysosome or proteasome inhibitors, suggesting the involvement of both degradation pathways. Our findings highlight the potential therapeutic role of ATRA in Alzheimer's disease and related tauopathies. By enhancing Hsp90 expression and facilitating tau degradation, ATRA could contribute to the clearance of pathological tau proteins, offering a promising strategy for mitigating neurodegeneration. This research underscores the need for further exploration into the molecular mechanisms of tau protein internalization and degradation, which could provide valuable insights into the treatment of neurodegenerative diseases.

Rosuvastatin attenuates total-tau serum levels and increases expression of miR-124-3p in dyslipidemic Alzheimer's patients: a historic cohort study

microRNAs are candidate diagnostic biomarkers for Alzheimer's disease. This study aimed to compare Silymarin with Rosuvastatin and placebo on total-Tau protein level and expression levels of microRNAs and TGF-β and COX-2 in Alzheimer's patients with secondary dyslipidemia. 36 mild AD patients with dyslipidemia were divided into three groups of 12. The first group received silymarin (140mg), the second group received placebo (140mg), and the third group recieved Rosuvastatin (10mg). Tablets were administered three times a day for Six months. The blood samples of the patients were collected before and after the intervention and the serum was separated. Using the RT-qPCR method, the expression levels of miR-124-3p and miR-125b-5p were assessed, and the serum levels of total-Tau, TGF-β, and COX-2 enzyme were measured using the ELISA method. Data were analyzed with SPSS software. In this study, the level of Δtotal-Tau was significantly lower in the Rosuvastatin group compared to the placebo (P = 0.038). Also, a significant reduction in the level of ΔTGF-β was observed in the Silymarin to Rosuvastatin group (p = 0.046) and ΔmiR-124-3p was significantly increased in the Rosuvastatin compared to the placebo group (p = 0.044). Rosuvastatin outperformed silymarin in decreasing Δtotal-Tau serum levels and enhancing expression of ΔmiR-124-3p, attributed to Rosuvastatin's capacity to lower cholesterol levels and inflammation concurrently. Conversely, silymarin was more effective than Rosuvastatin in reducing levels of ΔTGF-β. Serum miR-124-3p could serve as a promising diagnostic biomarker and a new therapeutic focus in AD.

Exercise: Just What the Doctor Ordered, But Why? Elucidating Mechanisms for Women's Increased High-Density Lipoprotein Benefit From Exercise and for the Health ABC Study

High-density lipoprotein (HDL) is protective against cardiovascular disease. Exercise can increase HDL concentration, and some evidence suggests that this effect occurs more strongly in women than in men. Both HDL and exercise are associated with inflammation. We hypothesized a sex-by-exercise interaction on HDL level, whereby women would benefit from exercise more strongly than men, and tumor necrosis factor alpha and serum soluble tumor necrosis factor receptor-2 would mediate this relationship. This study included 2,957 older adult participants (1,520 women; 41% Black, 59% White; 73.6-years-old) from the Health, Aging, and Body Composition study. Regression models revealed a positive exercise-HDL relationship in women only (sex-by-exercise interaction: β = 0.09, p = .013; exercise on HDL in women: β = 0.07, p = .015), mediated by TNFα (axb = 0.15; CI: 0.01, 0.30), suggesting that exercise may increase HDL levels in women through reduced inflammation. Given that vascular risk contributes to Alzheimer's disease risk, findings have implications for sex differences in AD risk factors.

Microbiota-Gut-Brain Axis Dysregulation in Alzheimer's Disease: Multi-Pathway Effects and Therapeutic Potential

An essential regulator of neurodegenerative conditions like Alzheimer's disease (AD) is the gut microbiota. Alterations in intestinal permeability brought on by gut microbiota dysregulation encourage neuroinflammation, central immune dysregulation, and peripheral immunological dysregulation in AD, as well as hasten aberrant protein aggregation and neuronal death in the brain. However, it is unclear how the gut microbiota transmits information to the brain and how it influences brain cognition and function. In this review, we summarized the multiple pathways involved in the gut microbiome in AD and provided detailed treatment strategies based on the gut microbiome. Based on these observations, this review also discusses the problems, challenges, and strategies to address current therapeutic strategies.

Study on the role and mechanism of Tan IIA in Alzheimer's disease based on CREB-BDNF-TrkB pathway

The occurrence and development of Alzheimer's disease (AD) is closely related to neuronal loss, inflammatory response, cholinergic imbalance, and Tau protein hyperphosphorylation. Previous studies have confirmed that Streptozotocin (STZ) can be used to establish a rat model of AD by injecting it into the rat brain via the lateral ventricle. Our previous research showed that Danshentone IIA (Tan IIA) can improve cognitive dysfunction in rats caused by CC chemokine ligand 2, and network pharmacology results show that Tan IIA is very likely to improve AD symptoms through the cyclic adenosine monophosphate response element binding protein (CREB), brain-derived neurotrophic factor (BDNF), and tyrosine kinase receptor protein (TrkB) pathway. The results of the water maze experiment showed that after Tan IIA treatment, the escape latency of AD rats was shortened and the number of platform crossings increased; in the new object recognition experiment, the discrimination index of AD rats significantly increased after treatment; Nissl staining and Tunel staining results showed that Tan IIA increased the number of surviving neurons in the hippocampus of cognitively impaired rats and reduced neuronal apoptosis; Bielschowsky silver staining results showed that Tan IIA reduced neurofibrillary tangles (NFTs) in the AD rats; Tan IIA can reduce the inflammatory response and oxidative stress reaction in the hippocampus of AD rats, and at the same time reduce the activity of acetylcholinesterase. Tan IIA can significantly increase the expression of CREB, BDNF, TrkB in the hippocampal tissue of STZ-injured rats (P < 0.05). These data suggest that Tan IIA may upregulate the expression of the CREB-BDNF-TrkB signaling pathway in the hippocampus of brain tissue, produce anti-neuroinflammatory, antioxidant stress, inhibit neuronal apoptosis effects, and improve cholinergic neurotransmitter disorder induced by STZ, reduce the neuronal damage and learning and memory impairment caused by STZ in rats, and improve the cognitive function of rats.

Neurotoxic Microglial Activation via IFNγ-Induced Nrf2 Reduction Exacerbating Alzheimer's Disease

Microglial neuroinflammation appears to be neuroprotective in the early pathological stage, yet neurotoxic, which often precedes neurodegeneration in Alzheimer's disease (AD). However, it remains unclear how the microglial activities transit to the neurotoxic state during AD progression, due to complex neuron-glia interactions. Here, the mechanism of detrimental microgliosis in AD by employing 3D human AD mini-brains, brain tissues of AD patients, and 5XFAD mice is explored. In the human and animal AD models, amyloid-beta (Aβ)-overexpressing neurons and reactive astrocytes produce interferon-gamma (IFNγ) and excessive oxidative stress. IFNγ results in the downregulation of mitogen-activated protein kinase (MAPK) and the upregulation of Kelch-like ECH-associated Protein 1 (Keap1) in microglia, which inactivate nuclear factor erythroid-2-related factor 2 (Nrf2) and sensitize microglia to the oxidative stress and induces a proinflammatory microglia via nuclear factor kappa B (NFκB)-axis. The proinflammatory microglia in turn produce neurotoxic nitric oxide and proinflammatory mediators exacerbating synaptic impairment, phosphorylated-tau accumulation, and discernable neuronal loss. Interestingly, recovering Nrf2 in the microglia prevents the activation of proinflammatory microglia and significantly blocks the tauopathy in AD minibrains. Taken together, it is envisioned that IFNγ-driven Nrf2 downregulation in microglia as a key target to ameliorate AD pathology.

Tau seeds from Alzheimer's disease brains trigger tau spread in macaques while oligomeric-Aβ mediates pathology maturation

INTRODUCTION

The "prion-like" features of Alzheimer's disease (AD) tauopathy and its relationship with amyloid-β (Aβ) have never been experimentally studied in primates phylogenetically close to humans.

METHODS

We injected 17 macaques in the entorhinal cortex with nanograms of seeding-competent tau aggregates purified from AD brains or control extracts from aged-matched healthy brains, with or without intracerebroventricular co-injections of oligomeric-Aβ.

RESULTS

Pathological tau injection increased cerebrospinal fluid (CSF) p-tau181 concentration after 18 months. Tau pathology spreads from the entorhinal cortex to the hippocampal trisynaptic loop and the cingulate cortex, resuming the experimental progression of Braak stage I to IV. Many AD-related molecular networks were impacted by tau seeds injections regardless of Aβ injections in proteomic analyses. However, we found mature neurofibrillary tangles, increased CSF total-tau concentration, and pre- and postsynaptic degeneration only in Aβ co-injected macaques.

DISCUSSION

Oligomeric-Aβ mediates the maturation of tau pathology and its neuronal toxicity in macaques but not its initial spreading.

HIGHLIGHTS

This study supports the "prion-like" properties of misfolded tau extracted from AD brains. This study empirically validates the Braak staging in an anthropomorphic brain. This study highlights the role of oligomeric Aβ in driving the maturation and toxicity of tau pathology. This work establishes a novel animal model of early sporadic AD that is closer to the human pathology.

Correlative factors of poor prognosis and abnormal cellular immune function in patients with Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a serious disease causing human dementia and social problems. The quality of life and prognosis of AD patients have attracted much attention. The role of chronic immune inflammation in the pathogenesis of AD is becoming more and more important.

AIM

To study the relationship among cognitive dysfunction, abnormal cellular immune function, neuroimaging results and poor prognostic factors in patients.

METHODS

A retrospective analysis of 62 hospitalized patients clinical diagnosed with AD who were admitted to our hospital from November 2015 to November 2020. Collect cognitive dysfunction performance characteristics, laboratory test data and neuroimaging data from medical records within 24 h of admission, including Mini Mental State Examination Scale score, drawing clock test, blood T lymphocyte subsets, and neutrophils and lymphocyte ratio (NLR), disturbance of consciousness, extrapyramidal symptoms, electroencephalogram (EEG) and head nucleus magnetic spectroscopy (MRS) and other data. Multivariate logistic regression analysis was used to determine independent prognostic factors. the modified Rankin scale (mRS) was used to determine whether the prognosis was good. The correlation between drug treatment and prognostic mRS score was tested by the rank sum test.

RESULTS

Univariate analysis showed that abnormal cellular immune function, extrapyramidal symptoms, obvious disturbance of consciousness, abnormal EEG, increased NLR, abnormal MRS, and complicated pneumonia were related to the poor prognosis of AD patients. Multivariate logistic regression analysis showed that the decrease in the proportion of T lymphocytes in the blood after abnormal cellular immune function (odd ratio: 2.078, 95% confidence interval: 1.156-3.986, P < 0.05) was an independent risk factor for predicting the poor prognosis of AD. The number of days of donepezil treatment to improve cognitive function was negatively correlated with mRS score (r = 0.578, P < 0.05).

CONCLUSION

The decrease in the proportion of T lymphocytes may have predictive value for the poor prognosis of AD. It is recommended that the proportion of T lymphocytes < 55% is used as the cut-off threshold for predicting the poor prognosis of AD. The early and continuous drug treatment is associated with a good prognosis.

Comparative proteomic analysis of cerebral cortex revealed neuroprotective mechanism of esculentoside A on Alzheimer's disease

Esculentoside A (EsA), isolated from phytolacca esculenta, is a saponin showing neuroprotective effect in the mouse models of Alzheimer's disease (AD). To investigate its action target and underlying mechanism, this study used the proteomics technique of isobaric tags for relative and absolute quantification (iTRAQ) to analyze the differentially expressed proteins (DEPs) in the cerebral cortex of EsA-treated and untreated triple-transgenic 3 × Tg-AD model mice. Proteomic comparison revealed 250, 436, and 903 DEPs in three group pairs, i.e. AD/Wild-type (WT), AD+5 mg/kg EsA/AD, AD+10 mg/kg EsA/AD, respectively. Among them 28 DEPs were commonly shared by three group pairs, and 25 of them showed reversed expression levels in the diseased group under the treatment of both doses of EsA. Bioinformatics analysis revealed that these DEPs were mainly linked to metabolism, synapses, apoptosis, learning and memory. EsA treatment restored the expression of these proteins, including amyloid precursor protein (APP), cathepsin B (Cstb), 4-aminobutyrate aminotransferase (Abat), 3-phosphoinositide-dependent protein kinase-1 (PDK1), carnitine palmitoyltransferase1 (Cpt1) and synaptotagmin 17 (Syt17), thereby ameliorated the spatial learning and memory of AD mice. Collectively, this study reveals for the first time the profound effect of EsA on the cerebral cortex of AD mice, which might be a potential therapeutic agent for the treatment of AD.

The cGAS-STING signaling pathway is modulated by urolithin A

During aging, general cellular processes, including autophagic clearance and immunological responses become compromised; therefore, identifying compounds that target these cellular processes is an important approach to improve our health span. The innate immune cGAS-STING pathway has emerged as an important signaling system in the organismal defense against viral and bacterial infections, inflammatory responses to cellular damage, regulation of autophagy, and tumor immunosurveillance. These key functions of the cGAS-STING pathway make it an attractive target for pharmacological intervention in disease treatments and in controlling inflammation and immunity. Here, we show that urolithin A (UA), an ellagic acid metabolite, exerts a profound effect on the expression of STING and enhances cGAS-STING activation and cytosolic DNA clearance in human cell lines. Animal laboratory models and limited human trials have reported no obvious adverse effects of UA administration. Thus, the use of UA alone or in combination with other pharmacological compounds may present a potential therapeutic approach in the treatment of human diseases that involves aberrant activation of the cGAS-STING pathway or accumulation of cytosolic DNA and this warrants further investigation in relevant transgenic animal models.

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

Distinguishing features of depression in dementia from primary psychiatric disease

Depression is a common and devastating neuropsychiatric symptom in the elderly and in patients with dementia. In particular, nearly 80% of patients with Alzheimer's Disease dementia experience depression during disease development and progression. However, it is unknown whether the depression in patients with dementia shares the same molecular mechanisms as depression presenting as primary psychiatric disease or occurs and persists through alternative mechanisms. In this review, we discuss how the clinical presentation and treatment differ between depression in dementia and as a primary psychiatric disease, with a focus on major depressive disorder. Then, we hypothesize several molecular mechanisms that may be unique to depression in dementia such as neuropathological changes, inflammation, and vascular events. Finally, we discuss existing issues and future directions for investigation and treatment of depression in dementia.

Current Perspectives: Obesity and Neurodegeneration - Links and Risks

Obesity is increasing in prevalence across all age groups. Long-term obesity can lead to the development of metabolic and cardiovascular diseases through its effects on adipose, skeletal muscle, and liver tissue. Pathological mechanisms associated with obesity include immune response and inflammation as well as oxidative stress and consequent endothelial and mitochondrial dysfunction. Recent evidence links obesity to diminished brain health and neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Both AD and PD are associated with insulin resistance, an underlying syndrome of obesity. Despite these links, causative mechanism(s) resulting in neurodegenerative disease remain unclear. This review discusses relationships between obesity, AD, and PD, including clinical and preclinical findings. The review then briefly explores nonpharmacological directions for intervention.

Monoclonal Antibody Therapy in Alzheimer's Disease

Alzheimer's disease is a neurodegenerative condition marked by the progressive deterioration of cognitive abilities, memory impairment, and the accumulation of abnormal proteins, specifically beta-amyloid plaques and tau tangles, within the brain. Despite extensive research efforts, Alzheimer's disease remains without a cure, presenting a significant global healthcare challenge. Recently, there has been an increased focus on antibody-based treatments as a potentially effective method for dealing with Alzheimer's disease. This paper offers a comprehensive overview of the current status of research on antibody-based molecules as therapies for Alzheimer's disease. We will briefly mention their mechanisms of action, therapeutic efficacy, and safety profiles while addressing the challenges and limitations encountered during their development. We also highlight some crucial considerations in antibody-based treatment development, including patient selection criteria, dosing regimens, or safety concerns. In conclusion, antibody-based therapies present a hopeful outlook for addressing Alzheimer's disease. While challenges remain, the accumulating evidence suggests that these therapies may offer substantial promise in ameliorating or preventing the progression of this debilitating condition, thus potentially enhancing the quality of life for the millions of individuals and families affected by Alzheimer's disease worldwide.

Alzheimer's disease: The role of T lymphocytes in neuroinflammation and neurodegeneration

Alzheimer's disease, the leading cause of progressive cognitive decline globally, has been reported to be enhanced by neuroinflammation. Brain-resident innate immune cells and adaptive immune cells work together to produce neuroinflammation. Studies over the past decade have established the neuroimmune axis present in Alzheimer's disease; the crosstalk between adaptive and innate immune cells within and outside the brain is crucial to the onset and progression of Alzheimer's disease. Although the role of the adaptive immune system in Alzheimer's disease is not fully understood, it has been hypothesized that the brain's immune homeostasis is significantly disrupted, which greatly contributes to neuroinflammation. Brain-infiltrating T cells possess proinflammatory phenotypes and activities that directly contribute to neuroinflammation. The pro-inflammatory activities of the adaptive immune system in Alzheimer's disease are characterized by the upregulation of effector T cell activities and the downregulation of regulatory T cell activities in the brain, blood, and cerebrospinal fluid. In this review, we discuss the major impact of T lymphocytes on the pathogenesis and progression of Alzheimer's disease. Understanding the role and mechanism of action of T cells in Alzheimer's disease would significantly contribute to the identification of novel biomarkers for diagnosing and monitoring the progression of the disease. This knowledge could also be crucial to the development of immunotherapies for Alzheimer's disease.

Neuroprotection and Mechanism of Gas-miR36-5p from Gastrodia elata in an Alzheimer's Disease Model by Regulating Glycogen Synthase Kinase-3β

Alzheimer's disease (AD) is currently the most common neurodegenerative disease. Glycogen synthase kinase 3β (GSK-3β) is a pivotal factor in AD pathogenesis. Recent research has demonstrated that plant miRNAs exert cross-kingdom regulation on the target genes in animals. Gastrodia elata (G. elata) is a valuable traditional Chinese medicine that has significant pharmacological activity against diseases of the central nervous system (CNS). Our previous studies have indicated that G. elata-specific miRNA plays a cross-kingdom regulatory role for the NF-κB signaling pathway in mice. In this study, further bioinformatics analysis suggested that Gas-miR36-5p targets GSK-3β. Through western blot, RT-qPCR, and assessments of T-AOC, SOD, and MDA levels, Gas-miR36-5p demonstrated its neuroprotective effects in an AD cell model. Furthermore, Gas-miR36-5p was detected in the murine brain tissues. The results of the Morris water maze test and western blot analysis provided positive evidence for reversing the learning deficits and hyperphosphorylation of Tau in AD mice, elucidating significant neuroprotective effects in an AD model following G. elata RNA administration. Our research emphasizes Gas-miR36-5p as a novel G. elata-specific miRNA with neuroprotective properties in Alzheimer's disease by targeting GSK-3β. Consequently, our findings provide valuable insights into the cross-kingdom regulatory mechanisms underlying G. elata-specific miRNA, presenting a novel perspective for the treatment of Alzheimer's disease.

Neuroinflammation-Modulating Agent SB1617 Enhances LC3-Associated Phagocytosis to Mitigate Tau Pathology

Tau protein aggregation and propagation in neurons and surrounding microglia are well-known risk factors for neurodegenerative diseases. Therefore, emerging therapeutic strategies that target neuroinflammatory activity in microglia have the potential to prevent tauopathy. Here, we explored the microglia-mediated neuroprotective function of SB1617 against tau aggregation. Our study revealed that SB1617-inactivated pathogenic M1-like microglia, reduced the secretion of pro-inflammatory cytokines via translational regulation, and induced microglial polarization toward the M2 phenotype and phagocytic function. Furthermore, we observed that extracellular pathogenic tau aggregates were eliminated via LC3-associated phagocytosis. The in vivo efficacy of SB1617 was confirmed in mice with traumatic brain injury in which SB1617 exerted neuroprotective effects by reducing pathogenic tau levels through microglia-mediated anti-inflammatory activity. Our results indicated that SB1617-mediated microglial surveillance with LC3-associated phagocytosis is a critical molecular mechanism in the regulation of tau proteostasis. This study provides new insights into tauopathies and directions for developing novel therapies for neurodegenerative diseases.

Extracellular vesicles derived from Porphyromonas gingivalis induce trigeminal nerve-mediated cognitive impairment

INTRODUCTION

Porphyromonas gingivalis (PG)-infected periodontitis is in close connection with the development of Alzheimer's disease (AD). PG-derived extracellular vesicles (pEVs) contain inflammation-inducing virulence factors, including gingipains (GPs) and lipopolysaccharide (LPS).

OBJECTIVES

To understand how PG could cause cognitive decline, we investigated the effects of PG and pEVs on the etiology of periodontitis and cognitive impairment in mice.

METHODS

Cognitive behaviors were measured in the Y-maze and novel object recognition tasks. Biomarkers were measured using ELISA, qPCR, immunofluorescence assay, and pyrosequencing.

RESULTS

pEVs contained neurotoxic GPs and inflammation-inducible fimbria protein and LPS. Gingivally exposed, but not orally gavaged, PG or pEVs caused periodontitis and induced memory impairment-like behaviors. Gingival exposure to PG or pEVs increased TNF-α expression in the periodontal and hippocampus tissues. They also increased hippocampal GP+Iba1+, LPS+Iba1+, and NF-κB+Iba1+ cell numbers. Gingivally exposed PG or pEVs decreased BDNF, claudin-5, and N-methyl-D-aspartate receptor expression and BDNF+NeuN+ cell number. Gingivally exposed fluorescein-5-isothiocyanate-labeled pEVs (F-pEVs) were detected in the trigeminal ganglia and hippocampus. However, right trigeminal neurectomy inhibited the translocation of gingivally injected F-EVs into the right trigeminal ganglia. Gingivally exposed PG or pEVs increased blood LPS and TNF-α levels. Furthermore, they caused colitis and gut dysbiosis.

CONCLUSION

Gingivally infected PG, particularly pEVs, may cause cognitive decline with periodontitis. PG products pEVs and LPS may be translocated into the brain through the trigeminal nerve and periodontal blood pathways, respectively, resulting in the cognitive decline, which may cause colitis and gut dysbiosis. Therefore, pEVs may be a remarkable risk factor for dementia.

Oligodendrocyte progenitor cells in Alzheimer's disease: from physiology to pathology

Oligodendrocyte progenitor cells (OPCs) play pivotal roles in myelin formation and phagocytosis, communicating with neighboring cells and contributing to the integrity of the blood-brain barrier (BBB). However, under the pathological circumstances of Alzheimer's disease (AD), the brain's microenvironment undergoes detrimental changes that significantly impact OPCs and their functions. Starting with OPC functions, we delve into the transformation of OPCs to myelin-producing oligodendrocytes, the intricate signaling interactions with other cells in the central nervous system (CNS), and the fascinating process of phagocytosis, which influences the function of OPCs and affects CNS homeostasis. Moreover, we discuss the essential role of OPCs in BBB formation and highlight the critical contribution of OPCs in forming CNS-protective barriers. In the context of AD, the deterioration of the local microenvironment in the brain is discussed, mainly focusing on neuroinflammation, oxidative stress, and the accumulation of toxic proteins. The detrimental changes disturb the delicate balance in the brain, impacting the regenerative capacity of OPCs and compromising myelin integrity. Under pathological conditions, OPCs experience significant alterations in migration and proliferation, leading to impaired differentiation and a reduced ability to produce mature oligodendrocytes. Moreover, myelin degeneration and formation become increasingly active in AD, contributing to progressive neurodegeneration. Finally, we summarize the current therapeutic approaches targeting OPCs in AD. Strategies to revitalize OPC senescence, modulate signaling pathways to enhance OPC differentiation, and explore other potential therapeutic avenues are promising in alleviating the impact of AD on OPCs and CNS function. In conclusion, this review highlights the indispensable role of OPCs in CNS function and their involvement in the pathogenesis of AD. The intricate interplay between OPCs and the AD brain microenvironment underscores the complexity of neurodegenerative diseases. Insights from studying OPCs under pathological conditions provide a foundation for innovative therapeutic strategies targeting OPCs and fostering neurodegeneration. Future research will advance our understanding and management of neurodegenerative diseases, ultimately offering hope for effective treatments and improved quality of life for those affected by AD and related disorders.

The bexarotene derivative OAB-14 ameliorates cognitive decline in APP/PS1 transgenic mice by suppressing microglia-mediated neuroinflammation through the PPAR-γ pathway

Neuroinflammation is believed to be a critical process involved in the pathophysiology of Alzheimer's disease (AD). In this study, we investigated the pharmacological ability of OAB-14, a small molecule compound derived from bexarotene, to reduce neuroinflammation and improve cognitive decline in an AD mouse model (in vivo) and its ability to regulate signaling pathways implicated in neuroinflammation in vitro. It was found that OAB-14 significantly improved the cognitive function of 11-month-old AD mice (APP/PS1 transgenic mice) in a dose-dependent manner. Simultaneously, OAB-14 dramatically inhibited the activation of microglia in the cerebral cortex and hippocampus of AD mice and dose-dependently downregulated the expression of nuclear factor kappa B (NF-κB) and NOD-like receptor protein 3 (NLRP3) in the cerebral cortex. At the cellular level, OAB-14 reversed the downregulation of M2 phenotypic markers, including mannose receptor C-type 1 (MRC1) and arginase 1 (ARG1), in lipopolysaccharide (LPS)- or amyloid-β protein oligomer (oAβ1-42)-activated BV2 microglial cells and partially restored their ability to clear Aβ. However, these effects were suppressed when peroxisome proliferator-activated receptor-γ (PPAR-γ) was specifically inhibited by GW9662, a selective PPAR-γ antagonist. These results suggested that OAB-14 could regulate microglial polarization by regulating PPAR-γ signaling, thereby mitigating neuroinflammation and improving cognitive function in AD mice.

Aggregation, Transmission, and Toxicity of the Microtubule-Associated Protein Tau: A Complex Comprehension

The microtubule-associated protein tau is an intrinsically disordered protein containing a few short and transient secondary structures. Tau physiologically associates with microtubules (MTs) for its stabilization and detaches from MTs to regulate its dynamics. Under pathological conditions, tau is abnormally modified, detaches from MTs, and forms protein aggregates in neuronal and glial cells. Tau protein aggregates can be found in a number of devastating neurodegenerative diseases known as "tauopathies", such as Alzheimer's disease (AD), frontotemporal dementia (FTD), corticobasal degeneration (CBD), etc. However, it is still unclear how the tau protein is compacted into ordered protein aggregates, and the toxicity of the aggregates is still debated. Fortunately, there has been considerable progress in the study of tau in recent years, particularly in the understanding of the intercellular transmission of pathological tau species, the structure of tau aggregates, and the conformational change events in the tau polymerization process. In this review, we summarize the concepts of tau protein aggregation and discuss the views on tau protein transmission and toxicity.

Machine learning identification and immune infiltration of disulfidptosis-related Alzheimer's disease molecular subtypes

BACKGROUND

Alzheimer's disease (AD) is a common neurodegenerative disorder. Disulfidptosis is a newly discovered form of programmed cell death that holds promise as a therapeutic strategy for various disorders. However, the functional roles of disulfidptosis-related genes (DRGs) in AD remain unknown.

METHODS

Microarray data and clinical information from patients with AD and healthy controls were downloaded from the Gene Expression Omnibus database. A thorough examination of DRG expression and immune characteristics in both groups was performed. Based on the identified DRGs, we performed an unsupervised clustering analysis to categorize the AD samples into various disulfidptosis-related molecular clusters. Weighted gene co-expression network analysis was performed to select hub genes specific to disulfidptosis-related AD clusters. The performances of various machine learning models were compared to determine the optimal predictive model. The predictive ability of the optimal model was assessed using nomogram analysis and five external datasets.

RESULTS

Eight DRGs showed differential expression between the AD and control samples. Two different molecular clusters were identified. The immune cell infiltration analysis revealed distinct differences in the immune microenvironment of the two clusters. The support vector machine model showed the highest performance, and a panel of five signature genes was identified, which showed excellent performance on the external validation datasets. The nomogram analysis also showed high accuracy in predicting AD.

CONCLUSION

We identified disulfidptosis-related molecular clusters in AD and established a novel risk model to assess the likelihood of developing AD. These findings revealed a complex association between disulfidptosis and AD, which may aid in identifying potential therapeutic targets for this debilitating disorder.

Serum tau protein elevation in migraine: a cross-sectional case-control study

BACKGROUND

Migraine is a disorder associated with neuropeptide release, pain and inflammation. Tau protein has recently been linked to inflammatory diseases and can be influenced by neuropeptides such as CGRP, a key neurotransmitter in migraine. Here, we report serum concentrations of total-tau protein in migraine patients and healthy controls.

METHODS

In this cross-sectional study, interictal blood samples from n = 92 patients with episodic migraine (EM), n = 93 patients with chronic migraine (CM), and n = 42 healthy matched controls (HC) were studied. We assessed serum total-tau protein (t-tau) and for comparison neurofilament light chain protein (NfL), glial fibrillary acidic protein (GFAP), and ubiquitin carboxy-terminal hydrolase L (UCH-L1) concentrations using the Neurology 4-plex kit, on a single molecule array HD-X Analyzer (Quanterix Corp Lexington, MA). Matched serum/cerebrospinal fluid (CSF) samples were used for post-hoc evaluations of a central nervous system (CNS) source of relevant findings. We applied non-parametric tests to compare groups and assess correlations.

RESULTS

Serum t-tau concentrations were elevated in EM [0.320 (0.204 to 0.466) pg/mL] and CM [0.304 (0.158 to 0.406) pg/mL] patients compared to HC [0.200 (0.114 to 0.288) pg/mL] (p = 0.002 vs. EM; p = 0.025 vs. CM). EM with aura [0.291 (0.184 to 0.486 pg/mL); p = 0.013] and EM without aura [0.332 (0.234 to 0.449) pg/mL; p = 0.008] patients had higher t-tau levels than HC but did not differ between each other. Subgroup analysis of CM with/without preventive treatment revealed elevated t-tau levels compared to HC only in the non-prevention group [0.322 (0.181 to 0.463) pg/mL; p = 0.009]. T-tau was elevated in serum (p = 0.028) but not in cerebrospinal fluid (p = 0.760). In contrast to t-tau, all proteins associated with cell damage (NfL, GFAP, and UCH-L1), did not differ between groups.

DISCUSSION

Migraine is associated with t-tau elevation in serum but not in the CSF. Our clinical study identifies t-tau as a new target for migraine research.

Traumatic brain injury-associated epigenetic changes and the risk for neurodegenerative diseases

Epidemiological studies have shown that traumatic brain injury (TBI) increases the risk for developing neurodegenerative diseases (NDs). However, molecular mechanisms that underlie this risk are largely unidentified. TBI triggers widespread epigenetic modifications. Similarly, NDs such as Alzheimer's or Parkinson's are associated with numerous epigenetic changes. Although epigenetic changes can persist after TBI, it is unresolved if these modifications increase the risk of later ND development and/or dementia. We briefly review TBI-related epigenetic changes, and point out putative feedback loops that might contribute to long-term persistence of some modifications. We then focus on evidence suggesting persistent TBI-associated epigenetic changes may contribute to pathological processes (e.g., neuroinflammation) which may facilitate the development of specific NDs - Alzheimer's disease, Parkinson's disease, or chronic traumatic encephalopathy. Finally, we discuss possible directions for TBI therapies that may help prevent or delay development of NDs.

Anti-Amnesia-like Effect of Pinus densiflora Extract by Improving Apoptosis and Neuroinflammation on Trimethyltin-Induced ICR Mice

This study was conducted to investigate the anti-amnestic property of Korean red pine bark extract (KRPBE) on TMT-induced cognitive decline in ICR mice. As a result of looking at behavioral function, the consumption of KRPBE improved the spatial work ability, short-term learning, and memory ability by Y-maze, passive avoidance, and Morris water maze tests. KRPBE suppressed antioxidant system damage by assessing the SOD activity, reduced GSH content, and MDA levels in brain tissue. In addition, it had a protective effect on cholinergic and synaptic systems by regulating ACh levels, AChE activity, and protein expression levels of ChAT, AChE, SYP, and PSD-95. Also, the KRPBE ameliorated TMT-induced mitochondrial damage by regulating the ROS content, MMP, and ATP levels. Treatment with KRPBE suppressed Aβ accumulation and phosphorylation of tau and reduced the expression level of BAX/BCl-2 ratio and caspase 3, improving oxidative stress-induced apoptosis. Moreover, treatment with KRPBE improved cognitive dysfunction by regulating the neuro-inflammatory protein expression levels of p-JNK, p-Akt, p-IκB-α, COX-2, and IL-1β. Based on these results, the extract of Korean red pine bark, which is discarded as a byproduct of forestry, might be used as an eco-friendly material for functional foods or pharmaceuticals by having an anti-amnesia effect on cognitive impairment.

A microtubule stabilizer ameliorates protein pathogenesis and neurodegeneration in mouse models of repetitive traumatic brain injury

Tau pathogenesis is a hallmark of many neurodegenerative diseases, including Alzheimer's disease (AD). Although the events leading to initial tau misfolding and subsequent tau spreading in patient brains are largely unknown, traumatic brain injury (TBI) may be a risk factor for tau-mediated neurodegeneration. Using a repetitive TBI (rTBI) paradigm, we report that rTBI induced somatic accumulation of phosphorylated and misfolded tau, as well as neurodegeneration across multiple brain areas in 7-month-old tau transgenic PS19 mice but not wild-type (WT) mice. rTBI accelerated somatic tau pathology in younger PS19 mice and WT mice only after inoculation with tau preformed fibrils and AD brain-derived pathological tau (AD-tau), respectively, suggesting that tau seeds are needed for rTBI-induced somatic tau pathology. rTBI further disrupted axonal microtubules and induced punctate tau and TAR DNA binding protein 43 (TDP-43) pathology in the optic tracts of WT mice. These changes in the optic tract were associated with a decline of visual function. Treatment with a brain-penetrant microtubule-stabilizing molecule reduced rTBI-induced tau, TDP-43 pathogenesis, and neurodegeneration in the optic tract as well as visual dysfunction. Treatment with the microtubule stabilizer also alleviated rTBI-induced tau pathology in the cortices of AD-tau-inoculated WT mice. These results indicate that rTBI facilitates abnormal microtubule organization, pathological tau formation, and neurodegeneration and suggest microtubule stabilization as a potential therapeutic avenue for TBI-induced neurodegeneration.

Tau and neuroinflammation in Alzheimer's disease: interplay mechanisms and clinical translation

Alzheimer's Disease (AD) contributes to most cases of dementia. Its prominent neuropathological features are the extracellular neuritic plaques and intercellular neurofibrillary tangles composed of aggregated β-amyloid (Aβ) and hyperphosphorylated tau protein, respectively. In the past few decades, disease-modifying therapy targeting Aβ has been the focus of AD drug development. Even though it is encouraging that two of these drugs have recently received accelerated US Food and Drug Administration approval for AD treatment, their efficacy or long-term safety is controversial. Tau has received increasing attention as a potential therapeutic target, since evidence indicates that tau pathology is more associated with cognitive dysfunction. Moreover, inflammation, especially neuroinflammation, accompanies AD pathological processes and is also linked to cognitive deficits. Accumulating evidence indicates that inflammation has a complex and tight interplay with tau pathology. Here, we review recent evidence on the interaction between tau pathology, focusing on tau post-translational modification and dissemination, and neuroinflammatory responses, including glial cell activation and inflammatory signaling pathways. Then, we summarize the latest clinical trials targeting tau and neuroinflammation. Sustained and increased inflammatory responses in glial cells and neurons are pivotal cellular drivers and regulators of the exacerbation of tau pathology, which further contributes to its worsening by aggravating inflammatory responses. Unraveling the precise mechanisms underlying the relationship between tau pathology and neuroinflammation will provide new insights into the discovery and clinical translation of therapeutic targets for AD and other tau-related diseases (tauopathies). Targeting multiple pathologies and precision therapy strategies will be the crucial direction for developing drugs for AD and other tauopathies.

Potential Utility of Cerebrospinal Fluid Glycoprotein Nonmetastatic Melanoma Protein B as a Neuroinflammatory Diagnostic Biomarker in Mild Cognitive Impairment and Alzheimer's Disease

Alzheimer's disease (AD) is a very common neurodegenerative disorder characterized by the gradual loss of neurons and extracellular amyloid-peptide buildup. There is compelling evidence that the disease process depends on neuroinflammatory alterations, such as the activation of astrocytes and microglia cells. A transmembrane glycoprotein known as glycoprotein nonmetastatic melanoma protein B (GPNMB) plays a neuroprotective role during the development of neurodegeneration. To the best of our knowledge, this is the first investigation discussing the potential clinical usefulness of this protein in the AD continuum, especially in the MCI (mild cognitive impairment) stage. A total of 71 patients with AD or MCI as well as controls were enrolled in this study. The concentrations of GPNMB, YKL-40, Aβ1-42 (amyloid beta 1-42), Tau, and pTau and the Aβ1-42/1-40 ratio in the CSF (cerebrospinal fluid) were tested using immunological methods. The concentrations of both GPNMB and YKL-40 in the cerebrospinal fluid were significantly higher in patients with AD and MCI compared to the controls. Moreover, both proteins were biochemically associated with classical biomarkers of AD and were especially associated with the Aβ1-42/1-40 ratio and Tau and pTau levels in the whole study group. Elevated concentrations of GPNMB were observed in the Aβ(+) group of AD patients compared to the Aβ(-) subjects. Additionally, the diagnostic performance (AUC value) of GPNMB was higher than that of amyloid β1-42 in MCI patients compared with controls. Our study indicates that GPNMB might be a promising neuroinflammatory biomarker for the early diagnosis and prognosis of the AD continuum, with potential utility as a therapeutic target.

Extracellular tau stimulates phagocytosis of living neurons by activated microglia via Toll-like 4 receptor-NLRP3 inflammasome-caspase-1 signalling axis

In tauopathies, abnormal deposition of intracellular tau protein followed by gradual elevation of tau in cerebrospinal fluids and neuronal loss has been documented, however, the mechanism how actually neurons die under tau pathology is largely unknown. We have previously shown that extracellular tau protein (2N4R isoform) can stimulate microglia to phagocytose live neurons, i.e. cause neuronal death by primary phagocytosis, also known as phagoptosis. Here we show that tau protein induced caspase-1 activation in microglial cells via 'Toll-like' 4 (TLR4) receptors and neutral sphingomyelinase. Tau-induced neuronal loss was blocked by caspase-1 inhibitors (Ac-YVAD-CHO and VX-765) as well as by TLR4 antibodies. Inhibition of caspase-1 by Ac-YVAD-CHO prevented tau-induced exposure of phosphatidylserine on the outer leaflet of neuronal membranes and reduced microglial phagocytic activity. We also show that suppression of NLRP3 inflammasome, which is down-stream of TLR4 receptors and mediates caspase-1 activation, by a specific inhibitor (MCC550) also prevented tau-induced neuronal loss. Moreover, NADPH oxidase is also involved in tau-induced neurotoxicity since neuronal loss was abolished by its pharmacological inhibitor. Overall, our data indicate that extracellular tau protein stimulates microglia to phagocytose live neurons via Toll-like 4 receptor-NLRP3 inflammasome-caspase-1 axis and NADPH oxidase, each of which may serve as a potential molecular target for pharmacological treatment of tauopathies.

Lomerizine inhibits LPS-mediated neuroinflammation and tau hyperphosphorylation by modulating NLRP3, DYRK1A, and GSK3α/β

Introduction

Lomerizine is a calcium channel blocker that crosses the blood-brain barrier and is used clinically in the treatment of migraines. However, whether lomerizine is beneficial in modulating neuroinflammatory responses has not been tested yet.

Methods

To assess the potential of lomerizine for repurposing as a treatment for neuroinflammation, we investigated the effects of lomerizine on LPS-induced proinflammatory responses in BV2 microglial cells, Alzheimer's disease (AD) excitatory neurons differentiated from induced pluripotent stem cells (iPSCs), and in LPS-treated wild type mice.

Results

In BV2 microglial cells, lomerizine pretreatment significantly reduced LPS-evoked proinflammatory cytokine and NLRP3 mRNA levels. Similarly, lomerizine pretreatment significantly suppressed the increases in Iba-1, GFAP, proinflammatory cytokine and NLRP3 expression induced by LPS in wild-type mice. In addition, lomerizine posttreatment significantly decreased LPS-stimulated proinflammatory cytokine and SOD2 mRNA levels in BV2 microglial cells and/or wild-type mice. In LPS-treated wild-type mice and AD excitatory neurons differentiated from iPSCs, lomerizine pretreatment ameliorated tau hyperphosphorylation. Finally, lomerizine abolished the LPS-mediated activation of GSK3α/β and upregulation of DYRK1A, which is responsible for tau hyperphosphorylation, in wild-type mice.

Discussion

These data suggest that lomerizine attenuates LPS-mediated neuroinflammatory responses and tau hyperphosphorylation and is a potential drug for neuroinflammation- or tauopathy-associated diseases.

Mental Health: Pandemics, Epidemics and Tau Protein

Background

It is well established that a wide range of psychological disorders are influenced by the way people live, with lifestyle-related factors playing a substantial role. During the past decade, the effects of major disasters on mental health have drawn a lot of attention.

Aim

In this review, we compare clinical studies reporting a link between COVID-19 and other pandemics and mental health. Importantly, we also shed light on Tau protein and neurotransmitters as neurobiological factors that might explain this link.

Methods

A thorough PubMed search was done to gather and summarize published data on the COVID-19 pandemic's effect on mental health. Additionally, these studies were compared to previous research published on PubMed, triggering other pandemic and epidemic impacts on mental health.

Results

The COVID-19 epidemic has had the biggest impact on raising awareness about mental health. Moreover, the past century has seen an increase in the frequency of disease outbreaks like MERS-CoV, Ebola, and Influenza, which all had an impact on mental health. However, the exact role of these epidemics on mental health and brain functions is poorly understood.

Conclusion

Future research on the underlying pathways may yield essential information for the treatment and prevention of prospective mental diseases in light of the ongoing decline in mental health during the past 10 years.

Targeting gut-brain axis by dietary flavonoids ameliorate aging-related cognition decline: Evidences and mechanisms

Aging-related cognitive impairment, mainly Alzheimer's disease (AD), has been widely studied. However, effective prevention and treatment methods are still lacking. In recent years, researchers have observed beneficial effects of plant-based supplements, such as flavonoids, on cognitive protection. This provides a new clue for the prevention of cognitive dysfunction. Studies have shown that dietary flavonoids have neuroprotective effects, but the mechanism is not clear. In this review, we systematically reviewed the research progress on the effects of dietary flavonoids on gut microbes and their metabolites, and concluded that flavonoids could improve cognitive function through the gut-brain axis. Flavonoids can be absorbed through the intestine, cross the blood-brain barrier, and enter the brain tissue. Flavonoids can inhibit the expression and secretion of inflammatory factors in brain tissue, reduce the damage caused by oxidative stress, clear neural damage proteins and inhibit neuronal apoptosis, thereby ameliorating age-related cognitive disorders. Future work will continue to explore the gut-brain axis and target genes regulated by flavonoids. In addition, clinical research and its mechanisms need to be further explored to provide solutions or advise for patients with cognitive impairment.

Revisiting the neuroinflammation hypothesis in Alzheimer's disease: a focus on the druggability of current targets

Alzheimer's disease (AD) is the most common form of neurodegenerative disease and disability in the elderly; it is estimated to account for 60%-70% of all cases of dementia worldwide. The most relevant mechanistic hypothesis to explain AD symptoms is neurotoxicity induced by aggregated amyloid-β peptide (Aβ) and misfolded tau protein. These molecular entities are seemingly insufficient to explain AD as a multifactorial disease characterized by synaptic dysfunction, cognitive decline, psychotic symptoms, chronic inflammatory environment within the central nervous system (CNS), activated microglial cells, and dysfunctional gut microbiota. The discovery that AD is a neuroinflammatory disease linked to innate immunity phenomena started in the early nineties by several authors, including the ICC´s group that described, in 2004, the role IL-6 in AD-type phosphorylation of tau protein in deregulating the cdk5/p35 pathway. The "Theory of Neuroimmunomodulation", published in 2008, proposed the onset and progression of degenerative diseases as a multi-component "damage signals" phenomena, suggesting the feasibility of "multitarget" therapies in AD. This theory explains in detail the cascade of molecular events stemming from microglial disorder through the overactivation of the Cdk5/p35 pathway. All these knowledge have led to the rational search for inflammatory druggable targets against AD. The accumulated evidence on increased levels of inflammatory markers in the cerebrospinal fluid (CSF) of AD patients, along with reports describing CNS alterations caused by senescent immune cells in neuro-degenerative diseases, set out a conceptual framework in which the neuroinflammation hypothesis is being challenged from different angles towards developing new therapies against AD. The current evidence points to controversial findings in the search for therapeutic candidates to treat neuroinflammation in AD. In this article, we discuss a neuroimmune-modulatory perspective for pharmacological exploration of molecular targets against AD, as well as potential deleterious effects of modifying neuroinflammation in the brain parenchyma. We specifically focus on the role of B and T cells, immuno-senescence, the brain lymphatic system (BLS), gut-brain axis alterations, and dysfunctional interactions between neurons, microglia and astrocytes. We also outline a rational framework for identifying "druggable" targets for multi-mechanistic small molecules with therapeutic potential against AD.

The innate immune response in tauopathies

Tauopathies, which include frontotemporal dementia, Alzheimer's disease, and chronic traumatic encephalopathy, are a class of neurological disorders resulting from pathogenic tau aggregates. These aggregates disrupt neuronal health and function leading to the cognitive and physical decline of tauopathy patients. Genome-wide association studies and clinical evidence have brought to light the large role of the immune system in inducing and driving tau-mediated pathology. More specifically, innate immune genes are found to harbor tauopathy risk alleles, and innate immune pathways are upregulated throughout the course of disease. Experimental evidence has expanded on these findings by describing pivotal roles for the innate immune system in the regulation of tau kinases and tau aggregates. In this review, we summarize the literature implicating innate immune pathways as drivers of tauopathy.

The relationship between protein modified folding molecular network and Alzheimer's disease pathogenesis based on BAG2-HSC70-STUB1-MAPT expression patterns analysis

Background

Alzheimer's disease (AD) is the most common cause of dementia and cognitive decline, while its pathological mechanism remains unclear. Tauopathies is one of the most widely accepted hypotheses. In this study, the molecular network was established and the expression pattern of the core gene was analyzed, confirming that the dysfunction of protein folding and degradation is one of the critical factors for AD.

Methods

This study analyzed 9 normal people and 22 AD patients' microarray data obtained from GSE1297 in Gene Expression Omnibus (GEO) database. The matrix decomposition analysis was used to identify the correlation between the molecular network and AD. The mathematics of the relationship between the Mini-Mental State Examination (MMSE) and the expression level of the genes involved in the molecular network was found by Neural Network (NN). Furthermore, the Support Vector Machine (SVM) model was for classification according to the expression value of genes.

Results

The difference of eigenvalues is small in first three stages and increases dramatically in the severe stage. For example, the maximum eigenvalue changed to 0.79 in the severe group from 0.56 in the normal group. The sign of the elements in the eigenvectors of biggest eigenvalue reversed. The linear function of the relationship between clinical MMSE and gene expression values was observed. Then, the model of Neural Network (NN) is designed to predict the value of MMSE based on the linear function, and the predicted accuracy is up to 0.93. For the SVM classification, the accuracy of the model is 0.72.

Conclusion

This study shows that the molecular network of protein folding and degradation represented by "BAG2-HSC70-STUB1-MAPT" has a strong relationship with the occurrence and progression of AD, and this degree of correlation of the four genes gradually weakens with the progression of AD. The mathematical mapping of the relationship between gene expression and clinical MMSE was found, and it can be used in predicting MMSE or classification with high accuracy. These genes are expected to be potential biomarkers for early diagnosis and treatment of AD.

An Insight into Cellular and Molecular Mechanisms Underlying the Pathogenesis of Neurodegeneration in Alzheimer's Disease

Alzheimer's disease (AD) is the most prominent neurodegenerative disorder in the aging population. It is characterized by cognitive decline, gradual neurodegeneration, and the development of amyloid-β (Aβ)-plaques and neurofibrillary tangles, which constitute hyperphosphorylated tau. The early stages of neurodegeneration in AD include the loss of neurons, followed by synaptic impairment. Since the discovery of AD, substantial factual research has surfaced that outlines the disease's causes, molecular mechanisms, and prospective therapeutics, but a successful cure for the disease has not yet been discovered. This may be attributed to the complicated pathogenesis of AD, the absence of a well-defined molecular mechanism, and the constrained diagnostic resources and treatment options. To address the aforementioned challenges, extensive disease modeling is essential to fully comprehend the underlying mechanisms of AD, making it easier to design and develop effective treatment strategies. Emerging evidence over the past few decades supports the critical role of Aβ and tau in AD pathogenesis and the participation of glial cells in different molecular and cellular pathways. This review extensively discusses the current understanding concerning Aβ- and tau-associated molecular mechanisms and glial dysfunction in AD. Moreover, the critical risk factors associated with AD including genetics, aging, environmental variables, lifestyle habits, medical conditions, viral/bacterial infections, and psychiatric factors have been summarized. The present study will entice researchers to more thoroughly comprehend and explore the current status of the molecular mechanism of AD, which may assist in AD drug development in the forthcoming era.

Inflammatory panel cytokines are elevated in the neocortex of late-stage Alzheimer's disease but not Lewy body dementias

BACKGROUND

Chronically dysregulated neuroinflammation has been implicated in neurodegenerative dementias, with separate studies reporting increased brain levels of inflammatory mediators and gliosis in Alzheimer's disease (AD) as well as in Lewy body dementias (LBD). However, it is unclear whether the nature and extent of neuroinflammatory responses in LBD are comparable to those in AD. In this study, we performed head-to-head measurements of a panel of cytokines in the post-mortem neocortex of AD versus the two major clinical subtypes of LBD, namely, dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD).

METHODS

Post-mortem tissues from the mid-temporal cortex (Brodmann area 21) of a cohort of neuropathologically well-defined AD, PDD and DLB patients were processed and measured for a comprehensive range of cytokines (IL-1α, IL-1Ra, IL-8, IL-10, IL-12p70, IL-13, IFN-γ, GM-CSF and FGF-2) using a multiplex immunoassay platform. Associations between inflammation markers and neuropathological measures of neuritic plaques, neurofibrillary tangles as well as Lewy bodies were also performed.

RESULTS

We found IL-1α, IFN-γ, GM-CSF and IL-13 to be elevated in the mid-temporal cortex of AD patients. In contrast, none of the measured cytokines were significantly altered in either DLB or PDD. Similar cytokine changes were observed in two other neocortical areas of AD patients. Furthermore, increases of IL-1α, IFN-γ, GM-CSF, IL-10 and IL-13 associated with moderate-to-severe neurofibrillary tangle burden, but not with neuritic plaques or Lewy bodies. Our findings of elevated neocortical pro- and anti-inflammatory cytokines in AD, but not in DLB or PDD, suggest that neuroinflammatory responses are strongly linked to neurofibrillary tangle burden, which is higher in AD compared to LBD. In conclusion, neuroinflammation may not play a prominent role in the pathophysiology of late-stage LBD.

Distinct and joint effects of low and high levels of Aβ and tau deposition on cortical thickness

Alzheimer's disease (AD) is defined by the presence of Amyloid-β (Aβ),tau, and neurodegeneration (ATN framework) in the human cerebral cortex. Yet, prior studies have suggested that Aβ deposition can be associated with both cortical thinning and thickening. These contradictory results are attributed to small sample sizes, the presence versus absence of tau, and limited detectability in the earliest phase of protein deposition, which may begin in young adulthood and cannot be captured in studies enrolling only older subjects. In this study, we aimed to find the distinct and joint effects of Aβ andtau on neurodegeneration during the progression from normal to abnormal stages of pathologies that remain elusive. We used18F-MK6240 and 18F-Florbetaben/18F-Florbetapir positron emission tomography (PET) and magnetic resonance imaging (MRI) to quantify tau, Aβ, and cortical thickness in 590 participants ranging in age from 20 to 90. We performed multiple regression analyses to assess the distinct and joint effects of Aβ and tau on cortical thickness using 590 healthy control (HC) and mild cognitive impairment (MCI) participants (141 young, 394 HC elderlies, 52 MCI). We showed thatin participants with normal levels of global Aβdeposition, Aβ uptakewassignificantly associated with increasedcortical thickness regardless of tau (e.g., left entorhinal cortex with t > 3.241, p < 0.0013). The relationship between tau deposition and neurodegeneration was more complex: in participants with abnormal levels of global tau, tau uptake was associated with cortical thinning in several regions of the brain (e.g., left entorhinal with t < -2.80, p < 0.0096 and left insula with t-value < -4.284, p < 0.0001), as reported on prior neuroimaging and neuropathological studies. Surprisingly, in participants with normal levels of global tau, tau was found to be associated with cortical thickening. Moreover, in participants with abnormal levels of global Aβandtau, theresonancebetween them, defined as their correlation throughout the cortex, wasassociated strongly with cortical thinning even when controlling for a direct linear effect. We confirm prior findings of an association between Aβ deposition and cortical thickening and suggest this may also be the case in the earliest stages of deposition in normal aging. We also illustrate that resonance between high levels of Aβ and tau uptake is strongly associated with cortical thinning, emphasizing the effects of Aβ/tau synergy inAD pathogenesis.

Exploring the interaction between T-cell antigen receptor-related genes and MAPT or ACHE using integrated bioinformatics analysis

Alzheimer's disease (AD) is a neurodegenerative disease that primarily occurs in elderly individuals with cognitive impairment. Although extracellular β-amyloid (Aβ) accumulation and tau protein hyperphosphorylation are considered to be leading causes of AD, the molecular mechanism of AD remains unknown. Therefore, in this study, we aimed to explore potential biomarkers of AD. Next-generation sequencing (NGS) datasets, GSE173955 and GSE203206, were collected from the Gene Expression Omnibus (GEO) database. Analysis of differentially expressed genes (DEGs), gene ontology (GO) functional enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and protein-protein networks were performed to identify genes that are potentially associated with AD. Analysis of the DEG based protein-protein interaction (PPI) network using Cytoscape indicated that neuroinflammation and T-cell antigen receptor (TCR)-associated genes (LCK, ZAP70, and CD44) were the top three hub genes. Next, we validated these three hub genes in the AD database and utilized two machine learning models from different AD datasets (GSE15222) to observe their general relationship with AD. Analysis using the random forest classifier indicated that accuracy (78%) observed using the top three genes as inputs differed only slightly from that (84%) observed using all genes as inputs. Furthermore, another data set, GSE97760, which was analyzed using our novel eigenvalue decomposition method, indicated that the top three hub genes may be involved in tauopathies associated with AD, rather than Aβ pathology. In addition, protein-protein docking simulation revealed that the top hub genes could form stable binding sites with acetylcholinesterase (ACHE). This suggests a potential interaction between hub genes and ACHE, which plays an essential role in the development of anti-AD drug design. Overall, the findings of this study, which systematically analyzed several AD datasets, illustrated that LCK, ZAP70, and CD44 may be used as AD biomarkers. We also established a robust prediction model for classifying patients with AD.

The role of adenosine A2A receptors in Alzheimer's disease and tauopathies

Adenosine signals through four distinct G protein-coupled receptors that are located at various synapses, cell types and brain areas. Through them, adenosine regulates neuromodulation, neuronal signaling, learning and cognition as well as the sleep-wake cycle, all strongly impacted in neurogenerative disorders, among which Alzheimer's Disease (AD). AD is a complex form of cognitive deficits characterized by two pathological hallmarks: extracellular deposits of aggregated β-amyloid peptides and intraneuronal fibrillar aggregates of hyper- and abnormally phosphorylated Tau proteins. Both lesions contribute to the early dysfunction and loss of synapses which are strongly associated to the development of cognitive decline in AD patients. The present review focuses on the pathophysiological impact of the A_2ARs dysregulation observed in cognitive area from AD patients. We are reviewing not only evidence of the cellular changes in A_2AR levels in pathological conditions but also describe what is currently known about their consequences in term of synaptic plasticity, neuro-glial miscommunication and memory abilities. We finally summarize the proof-of-concept studies that support A_2AR as credible targets and the clinical interest to repurpose adenosine drugs for the treatment of AD and related disorders. This article is part of the Special Issue on "Purinergic Signaling: 50 years".

Mechanism of action deconvolution of the small-molecule pathological tau aggregation inhibitor Anle138b

BACKGROUND

A key histopathological hallmark of Alzheimer's disease (AD) is the presence of neurofibrillary tangles of aggregated microtubule-associated protein tau in neurons. Anle138b is a small molecule which has previously shown efficacy in mice in reducing tau aggregates and rescuing AD disease phenotypes.

METHODS

In this work, we employed bioinformatics analysis-including pathway enrichment and causal reasoning-of an in vitro tauopathy model. The model consisted of cultured rat cortical neurons either unseeded or seeded with tau aggregates derived from human AD patients, both of which were treated with Anle138b to generate hypotheses for its mode of action. In parallel, we used a collection of human target prediction models to predict direct targets of Anle138b based on its chemical structure.

RESULTS

Combining the different approaches, we found evidence supporting the hypothesis that the action of Anle138b involves several processes which are key to AD progression, including cholesterol homeostasis and neuroinflammation. On the pathway level, we found significantly enriched pathways related to these two processes including those entitled "Superpathway of cholesterol biosynthesis" and "Granulocyte adhesion and diapedesis". With causal reasoning, we inferred differential activity of SREBF1/2 (involved in cholesterol regulation) and mediators of the inflammatory response such as NFKB1 and RELA. Notably, our findings were also observed in Anle138b-treated unseeded neurons, meaning that the inferred processes are independent of tau pathology and thus represent the direct action of the compound in the cellular system. Through structure-based ligand-target prediction, we predicted the intracellular cholesterol carrier NPC1 as well as NF-κB subunits as potential targets of Anle138b, with structurally similar compounds in the model training set known to target the same proteins.

CONCLUSIONS

This study has generated feasible hypotheses for the potential mechanism of action of Anle138b, which will enable the development of future molecular interventions aiming to reduce tau pathology in AD patients.

Pathway-specific polygenic risk scores correlate with clinical status and Alzheimer's-related biomarkers

Background: APOE is the largest genetic risk factor for sporadic Alzheimer's disease (AD), but there is a substantial polygenic component as well. Polygenic risk scores (PRS) can summarize small effects across the genome but may obscure differential risk associated with different molecular processes and pathways. Variability at the genetic level may contribute to the extensive phenotypic heterogeneity of Alzheimer's disease (AD). Here, we examine polygenic risk impacting specific pathways associated with AD and examined its relationship with clinical status and AD biomarkers of amyloid, tau, and neurodegeneration (A/T/N). Methods: A total of 1,411 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) with genotyping data were included. Sets of variants identified from a pathway analysis of AD GWAS summary statistics were combined into clusters based on their assigned pathway. We constructed pathway-specific PRSs for each participant and tested their associations with diagnostic status (AD vs cognitively normal), abnormal levels of amyloid and ptau (positive vs negative), and hippocampal volume. The APOE region was excluded from all PRSs, and analyses controlled for APOE -ε4 carrier status. Results: Thirteen pathway clusters were identified relating to categories such as immune response, amyloid precursor processing, protein localization, lipid transport and binding, tyrosine kinase, and endocytosis. Eight pathway-specific PRSs were significantly associated with AD dementia diagnosis. Amyloid-positivity was associated with endocytosis and fibril formation, response misfolded protein, and regulation protein tyrosine PRSs. Ptau positivity and hippocampal volume were both related to protein localization and mitophagy PRS, and ptau positivity was additionally associated with an immune signaling PRS. A global AD PRS showed stronger associations with diagnosis and all biomarkers compared to pathway PRSs, suggesting a strong synergistic effect of all loci contributing to the global AD PRS. Conclusions: Pathway PRS may contribute to understanding separable disease processes, but do not appear to add significant power for predictive purposes. These findings demonstrate that, although genetic risk for AD is widely distributed, AD-phenotypes may be preferentially associated with risk in specific pathways. Defining genetic risk along multiple dimensions at the individual level may help clarify the etiological heterogeneity in AD.

PI3K-Akt signaling pathway based on network pharmacology for the anti-Alzheimer's disease effect of licorice stem flavonoids

Active ingredients were screened by TCMSP and swissADME, meanwhile, PharmMapper combined with UniProt database was used to predict the active ingredient target information, GeneCard database was employed to obtain Alzheimer's disease (AD)-related genes, Cytoscapes 3.7.2 software was utilized to map the active ingredient-target effect. Besides, Cytoscapes 3.7.2 software Bisogenet and Cyto NCA plug-in combined with STRING platform were utilized to map the protein-protein interaction (PPI) network, DAVID was employed for GO annotation, while KEGG plug-in was used for KEGG pathway enrichment. Mice were tested for inflammatory damage induced by intracerebral injection of lipopolysaccharide (LPS), as well as learning memory and anxiety by water maze and open field tests. In addition, the expression of Caspase-3 and Caspase-9, together with inflammatory factors TNF-α, IL-6, and IL-1β was analyzed in serum. The expression levels of proteins related to PI3K-Akt signaling pathway in the brain were detected by Western blot (WB) assay. According to the results of network pharmacology, there were 35 active ingredients of licorice stem and leaf flavonoids screened, which exerted the anti-Alzheimer's disease (AD) effects via 67 targets and activated 41 signaling pathways including the PI3K-Akt pathway. Furthermore, Behavioural results revealed that Licorice stem and leaf flavonoids improved the learning and memory abilities of model mice and significantly improved the anxiety caused by inflammatory brain damage. Moreover, as suggested by HE staining and TUNEL staining of brain sections, Glycyrrhiza glabra stem and leaf flavonoids alleviated morphological lesions and cell nuclear damage in brain tissue. Results: of brain homogenate supernatant assay demonstrated that Glycyrrhiza glabra stem and leaf flavonoids had a significant effect on the levels of oxidative indicators superoxide dismutase (SOD), catalase (CAT), malonaldehyde (MDA), acetylcholine (Ach), acetylcholinesterase (AchE), Caspase-3, Caspase-9 and serum inflammatory factors TNF-α, IL-6 and IL-1β. Additionally, WB assay results indicated that the PI3K-Akt signaling pathway was activated.