BACE1 Expression Research Articles

Gamma Wave Stimulation Affects BACE1 Levels and Promotes the Transition of Microglia from M1 State to M2 State

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder and it presents with the hallmark neuropathological features of amyloid-beta (Aβ) plaques, tau tangles and active neuroinflammation. Beta-site amyloid precursor protein cleaving enzyme 1 (BACE-1), a key mediator of increased Aβ, has been identified as the primary enzymatic source for production of this pathologic peptide while reactive microglial cells contribute to ongoing neurodegeneration perhaps through activation into their aggressive M1 state. The present study endeavors for the first time to address how gamma wave stimulation modulates BACE1 and microglial polarization (from M1 to beneficial M2) in different AD models. We hypothesize that gamma wave stimulation will reduce BACE1, decrease Aβ plaque burden and shift microglials towards M2 phenotype leading to reduced neuroinflammation and maintain cognitive function. This study will target mouse models of AD which have undergone gamma wave stimulation and its effects on BACE1 expression, microglial polarisation markers, Aβ plaque load and cognitive performance. Hypotheses the treatment will reduce BACE1 activity, decrease M1/M2 microglial ratio, improve cognitive performance and delay Aβ plaque accumulation These data suggest promising therapeutic strategies for neuroinflammation and amyloidogenesis in AD.

Autoantibodies to BACE1 promote Aβ accumulation and neurodegeneration in Alzheimer's disease.

The profile of autoantibodies is dysregulated in patients with Alzheimer's disease (AD). Autoantibodies to beta-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) are present in human blood. This study aims to investigate the clinical relevance and pathophysiological roles of autoantibodies to BACE1 in AD. Clinical investigations were conducted in two independent cohorts, the Chongqing cohort, and the Australian Imaging, Biomarkers, and Lifestyle (AIBL) cohort. The Chongqing cohort included 55 AD patients, 28 patients with non-AD dementia, and 70 cognitively normal subjects (CN). The AIBL cohort included 162 Aβ-PET- CN, 169 Aβ-PET+ cognitively normal subjects (preclinical AD), and 31 Aβ-PET+ cognitively impaired subjects (ClinicalAD). Plasma autoantibodies to BACE1 were determined by one-site Elisa. The associations of plasma autoantibodies to BACE1 with brain Aβ load and cognitive trajectory were investigated. The effects of autoantibodies to BACE1 on AD-type pathologies and underlying mechanisms were investigated in APP/PS1 mice and SH/APPswe/PS1wt cell lines. In the Chongqing cohort, plasma autoantibodies to BACE1 were higher in AD patients, in comparison with CN and non-AD dementia patients. In the AIBL cohort, plasma autoantibodies to BACE1 were highest in clinical AD patients, followed by preclinical AD and CN subjects. Higher autoantibodies to BACE1 were associated with an increased incidence of brain amyloid positivity conversion during follow-up. Autoantibodies to BACE1 exacerbated brain amyloid deposition and subsequent AD-type pathologies, including Tau hyperphosphorylation, neuroinflammation, and neurodegeneration in APP/PS1 mice. Autoantibodies to BACE1 increased Aβ production by promoting BACE1 expression through inhibiting PPARγ signaling. These findings suggest that autoantibodies to BACE1 are pathogenic in AD and the upregulation of these autoantibodies may promote the development of the disease. This study offers new insights into the mechanism of AD from an autoimmune perspective.

WuYou decoction effectively reduces neuronal damage, synaptic dysfunction, and Aβ production in rats exposed to chronic sleep deprivation by modulating the Aβ-related enzymes and SIRT1/Nrf2/NF-κB pathway

Ethnopharmacological relevanceChronic sleep deprivation (CSD) can result in neuronal damage, synaptic dysfunction, Aβ production, neuroinflammation, and ultimately cognitive deterioration. WuYou Decoction (WYD), a contemporary prescription, has shown promise in enhancing sleep quality and cognitive performance in individuals with insomnia. However, the specific molecular mechanisms responsible for the neuroprotective effects of WYD on CSD remain incompletely understood. Aim of the studyThis study aimed to investigate the neuroprotective effects of WYD on the CSD model and its molecular mechanism. Materials and methodsUHPLC-MS/MS analysis was utilized to analyze the active ingredients of WYD extract. The study employed the multi-platform water environment method to establish the CSD model in rats. Subsequent to treatment with varying doses of WYD in CSD rats, cognitive function and pathological alterations in hippocampus and cortex, including neuronal damage, synaptic dysfunction, Aβ production, and neuroinflammation, were evaluated through a combination of Morris Water Maze test, HE staining, Nissl staining, Golgi-Cox staining, Transmission electron microscope, ELISA, Immunohistochemistry staining, Immunofluorescence staining and Western blot. ResultsUHPLC-MS/MS analysis revealed a total of 99 active ingredients were identified from the WYD extract. The administration of WYD exhibited a mitigation of cognitive decline in the model of CSD, as evidenced by increased neuron count in the hippocampus and cortex, and improved density and length of dendritic spines in these brain regions. Furthermore, WYD was found to suppress the Aβ production, and inhibit the expression of BACE1, PS1, GFAP, IBA1, IL-1β, IL-6, TNF-α, phosphorylated IκBα (Ser32) and phosphorylated NF-κB p65 (Ser536) in the hippocampus and cortex, while also increasing the levels of PSD95, SYN1, ADAM10, IDE, SIRT1 and Nrf2. ConclusionsWYD exhibits neuroprotective properties in CSD, potentially through modulation of the Aβ-related enzymes and SIRT1/Nrf2/NF-κB pathway.

Social isolation impairs cognition via Aβ-mediated synaptic dysfunction

Social isolation (SI) is a common phenomenon in the modern world, especially during the coronavirus disease 2019 pandemic, and causes lasting cognitive impairments and mental disorders. However, it is still unclear how SI alters molecules in the brain and induces behavioural dysfunctions. Here, we report that SI impairs cognitive function and induces depressive-like behaviours in C57BL/6 J mice, in addition to impairing synaptic plasticity and increasing the levels of APP cleavage-related enzymes, thereby promoting Aβ production. Moreover, we show that in APP/PS1 transgenic mice, SI accelerates pathological changes and behavioural deficits. Interestingly, downregulation of the expression of the BACE1 attenuates SI-induced Aβ toxicity and synaptic dysfunction. Furthermore, early intervention with BACE1 shRNA blocks SI-induced cognitive impairments. Together, our data strongly suggest that SI-induced upregulation of BACE1 expression mediates Aβ toxicity and induces behavioural deficits. Down-regulation of BACE1 may be a promising strategy for preventing SI-induced cognitive impairments.

Characteristics of streptozotocin-induced and okadaic acid-induced models of Alzheimer's disease

alzheimer's disease is the main cause of dementia in people over the age of 65, which affects millions of patients worldwide. Since the prevalence of this pathology increases significantly with the increase in life expectancy, the societal consequences of Alzheimer's disease will be dire if no effective therapy is developed in the near future. Fundamental experimental work is a mandatory and necessary stage of preclinical research for the safe and effective development of new approaches to the treatment of dementia as part of clinical trials in the future. Streptozotocin is a natural chemical obtained from Streptomyces achromogenes, primarily classified as an antibiotic, the introduction of which leads to the activation of oxidative stress and damage to the myelin sheath. This chemical compound promotes the accumulation of characteristic abnormal proteins, called β-amyloid and tau protein, which leads to imitation of neuropathological, behavioral, metabolic and molecular symptoms that resemble human Alzheimer's disease. Okadaic acid is a C38 fatty acid polyester phycotoxin, which is a powerful and selective inhibitor of serine/threonine phosphatases: PP-1c, PP1, PP2A and PP2B, which leads to a decrease in dephosphorylation of phosphorylated tau protein and, accordingly, to hyperphosphorylation of tau protein. Hyperphosphorylation of tau protein is responsible for the deposition of neurofibrillary tangles in vivo and in vitro, which ultimately causes synaptic dysfunction and neuronal death. In addition, okadaic acid activates kinases that regulate tau protein phosphorylation: GSK3β, CDK5, MAPK, ERK1/2, AMPK. The activation of kinases significantly contributes to the phosphorylation of tau protein. Okadain administration is also reported to significantly activate the expression of BACE1, one of the key enzymes in the amyloidogenic cascade. The mechanisms of molecular and morphological changes of the Alzheimer's type in the brain of experimental animals when streptozotocin and okadaic acid are administered are similar in many respects. These include induction and activation of neurodegeneration, apoptosis and necrosis of neurons, development of oxidative stress and inhibition of antioxidant systems, deficiency of neurotransmitters and mitochondrial dysfunction, etc. Both proposed toxins effectively contribute to the simulation of dementia of the Alzheimer's type in the experiment.

Engineered exosomes with a photoinducible protein delivery system enable CRISPR-Cas-based epigenome editing in Alzheimer's disease.

Effective intracellular delivery of therapeutic proteins can potentially treat a wide array of diseases. However, efficient delivery of functional proteins across the cell membrane remains challenging. Exosomes are nanosized vesicles naturally secreted by various types of cells and may serve as promising nanocarriers for therapeutic biomolecules. Here, we engineered exosomes equipped with a photoinducible cargo protein release system, termed mMaple3-mediated protein loading into and release from exosome (MAPLEX), in which cargo proteins can be loaded into the exosomes by fusing them with photocleavable protein (mMaple3)-conjugated exosomal membrane markers and subsequently released from the exosomal membrane by inducing photocleavage with blue light illumination. Using this system, we first induced transcriptional regulation by delivering octamer-binding transcription factor 4 and SRY-box transcription factor 2 to fibroblasts in vitro. Second, we induced in vivo gene recombination in Cre reporter mice by delivering Cre recombinase. Last, we achieved targeted epigenome editing in the brains of 5xFAD and 3xTg-AD mice, two models of Alzheimer's disease. Administration of MAPLEXs loaded with β-site amyloid precursor protein cleaving enzyme 1 (Bace1)-targeting single guide RNA-incorporated dCas9 ribonucleoprotein complexes, coupled with the catalytic domain of DNA methyltransferase 3A, resulted in successful methylation of the targeted CpG sites within the Bace1 promoter. This approach led to a significant reduction in Bace1 expression, improved recognition memory impairment, and reduced amyloid pathology in 5xFAD and 3xTg-AD mice. These results suggest that MAPLEX is an efficient intracellular protein delivery system that can deliver diverse therapeutic proteins for multiple diseases.

Tetramethylpyrazine Nitrone (TBN) Reduces Amyloid β Deposition in Alzheimer's Disease Models by Modulating APP Expression, BACE1 Activity, and Autophagy Pathways.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with age. A wealth of evidence indicates that the amyloid β (Aβ) aggregates result from dyshomeostasis between Aβ production and clearance, which plays a pivotal role in the pathogenesis of AD. Consequently, therapies targeting Aβ reduction represent a promising strategy for AD intervention. Tetramethylpyrazine nitrone (TBN) is a novel tetramethylpyrazine derivative with potential for the treatment of AD. Previously, we demonstrated that TBN markedly enhanced cognitive functions and decreased the levels of Aβ, APP, BACE 1, and hyperphosphorylated tau in 3×Tg-AD mice. However, the mechanism by which TBN inhibits Aβ deposition is still unclear. In this study, we employed APP/PS1 mice treated with TBN (60 mg/kg, ig, bid) for six months, and N2a/APP695swe cells treated with TBN (300 μM) to explore the mechanism of TBN in Aβ reduction. Our results indicate that TBN significantly alleviated cognitive impairment and reduced Aβ deposition in APP/PS1 mice. Further investigation of the underlying mechanisms revealed that TBN decreased the expression of APP and BACE1, activated the AMPK/mTOR/ULK1 autophagy pathway, inhibited the PI3K/AKT/mTOR/ULK1 autophagy pathway, and decreased the phosphorylation levels of JNK and ERK in APP/PS1 mice. Moreover, TBN was found to significantly reduce the mRNA levels of APP and BACE1, as well as those of SP1, CTCF, TGF-β, and NF-κB, transcription factors involved in regulating gene expression. Additionally, TBN was observed to decrease the level of miR-346 and increase the levels of miR-147 and miR-106a in the N2a/APP695swe cells. These findings indicate that TBN may reduce Aβ levels likely by reducing APP expression by regulating APP gene transcriptional factors and miRNAs, reducing BACE1 expression, and promoting autophagy activities.

Proteomic Analysis Reveals Physiological Activities of Aβ Peptide for Alzheimer's Disease.

With the rapid progress in deciphering the pathogenesis of Alzheimer's disease (AD), it has been widely accepted that the accumulation of misfolded amyloid β (Aβ) in the brain could cause the neurodegeneration in AD. Although much evidence demonstrates the neurotoxicity of Aβ, the role of Aβ in the nervous system are complex. However, more comprehensive studies are needed to understand the physiological effect of Aβ40 monomers in depth. To explore the physiological mechanism of Aβ, we employed mass spectrometry to investigate the altered proteomic events induced by a lower submicromolar concentration of Aβ. Human neuroblastoma SH-SY5Y cells were exposed to five different concentrations of Aβ1-40 monomers and collected at four time points. The proteomic analysis revealed the time-course behavior of proteins involved in biological processes, such as RNA splicing, nuclear transport and protein localization. Further biological studies indicated that Aβ40 monomers may activate PI3K/AKT signaling to regulate p-Tau, Ezrin and MAP2. These three proteins are associated with dendritic morphogenesis, neuronal polarity, synaptogenesis, axon establishment and axon elongation. Moreover, Aβ40 monomers may regulate their physiological forms by inhibiting the expression of BACE1 and APP via activation of the ERK1/2 pathway. A comprehensive exploration of pathological and physiological mechanisms of Aβ is beneficial for exploring novel treatment.

Early biomarkers in the presymptomatic phase of cognitive impairment: changes in the endocannabinoidome and serotonergic pathways in Alzheimer's-prone mice after mTBI

BackgroundDespite extensive studies on the neurobiological correlates of traumatic brain injury (TBI), little is known about its molecular determinants on long-term consequences, such as dementia and Alzheimer’s disease (AD).MethodsHere, we carried out behavioural studies and an extensive biomolecular analysis, including inflammatory cytokines, gene expression and the combination of LC-HRMS and MALDI-MS Imaging to elucidate the targeted metabolomics and lipidomics spatiotemporal alterations of brains from wild-type and APP-SWE mice, a genetic model of AD, at the presymptomatic stage, subjected to mild TBI.ResultsWe found that brain injury does not affect cognitive performance in APP-SWE mice. However, we detected an increase of key hallmarks of AD, including Aβ1-42 levels and BACE1 expression, in the cortices of traumatized transgenic mice. Moreover, significant changes in the expanded endocannabinoid (eCB) system, or endocannabinoidome (eCBome), occurred, including increased levels of the endocannabinoid 2-AG in APP-SWE mice in both the cortex and hippocampus, and N-acylserotonins, detected for the first time in the brain. The gene expression of enzymes for the biosynthesis and inactivation of eCBs and eCB-like mediators, and some of their main molecular targets, also underwent significant changes. We also identified the formation of heteromers between cannabinoid 1 (CB1) and serotonergic 2A (5HT2A) receptors, whose levels increased in the cortex of APP-SWE mTBI mice, possibly contributing to the exacerbated pathophysiology of AD induced by the trauma.ConclusionsMild TBI induces biochemical changes in AD genetically predisposed mice and the eCBome may play a role in the pathogenetic link between brain injury and neurodegenerative disorders also by interacting with the serotonergic system.

Heterologous expression of BACE1 and its interaction with Codonopsis pilosula polysaccharides and Lobetyolin

BACE1, a crucial enzyme in the amyloid-β deposition theory of Alzheimer's disease (AD), is targeted by Codonopsis pilosula, a traditional tonic believed to impede AD onset. However, the specific active compounds responsible for its effects remain elusive. Our prior network pharmacology research identified C. pilosula polysaccharides (CPPS) and Lobetyolin may serve as potential inhibitors of AD by suppressing amyloidogenesis. Here, we recombinantly expressed BACE1 under varied conditions and assessed its activity using Fluorescence Resonance Energy Transfer technology. Through spectroscopy, molecular docking, and dynamics, we elucidated the interactions of CPPS, Lobetyolin, and BACE1. Optimal BACE1 expression occurred at 22 °C with 0.4 mM IPTG for 6 h, yielding a 72 kDa protein. Enzyme kinetics displayed a maximum rate of 4096 μmol/min and a Michaelis constant of 16 mg/mL for BACE1. Spectroscopic analysis revealed differing binding affinities of the compounds at various temperatures, peaking at 293 K. Lobetyolin exhibited superior binding to BACE1 compared to CPPS, driven by hydrophobic and electrostatic forces. Molecular docking and dynamics highlighted hydrophobic amino acids' role in BACE1 interactions with Lobetyolin and CPPS, with binding energy < −1.2 kcal/mol signifying strong affinities. Notably, Lobetyolin and CPPS showed higher BACE1 affinity than APP, with the Lobetyolin-BACE1 complex being the most stable.

Phloroglucinol ameliorated methylglyoxal induced harmful effects in rats.

Glycation is among the underlying mechanisms attributed to ageing and associated morbidities. There is no drug available to combat this deleterious phenomenon. The present study aimed to explore phloroglucinol (PHL) for its anti-glycation potential at preclinical level. The rats were treated with methylglyoxal (MGO, 17.25 mg/kg, i.p. for 14 days) to induce glvcative stress. The treatment groups received additional administration of test drug (PHL; 0.25mg/kg, 0.5mg/kg, and 1mg/kg) or standard aminoguanidine (AG, 50 mg/kg) or saline (control, 5ml/kg). During 14 days, the weight and food intake was noted. Afterwards, the cognitive function was evaluated using Morris Water Maze (MWM) while hepatic and renal functions were assessed through liver function test (bilirubin, alkaline phosphatase, SGPT, and SGOT) and creatinine respectively, using chemical analyzer. The carboxymethyllysine (CML) levels were quantified in the blood using ELISA technique. Histopathological study was performed on the brain, liver, and kidney using H&E staining. Additionally, the qPCR was used to quantify the expression of TNF-α, RAGE and BACE-1 (brain), RAGE, TNF-α, and glyoxalase-I (liver) and RAGE, TNF-α, and VEGF (kidney), while glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as a reference housekeeping gene. The data regarding weight and food intake did not reveal significant alterations. In MWM, the MGO treatment caused significant increase in the time to reach target quadrant, while decrease in the time spent in target quadrant and number of crossings through platform position. All these effects were inhibited by both AG and PHL. The navigation maps also exhibit that the retention of spatial memory. Additionally, the MGO-induced alteration in hepatic and renal function indicators was ameliorated by both AG and PHL treatments. The plasma CML levels were found to be elevated following MGO treatment, while the concomitant administration of AG and PHL has resisted this raise. Histopathological assessment revealed no specific pathology in liver kidney and brain tissues. The qPCR data revealed enhanced expression of all genes, especially TNF-α and BACE, which were found to be reduced following both AG and PHL treatments. PHL prevented the brain, hepatic, and renal impairments caused by MGO induced glycative stress. Hence, the PHL, a clinically used anti-spasmodic drug, presents itself as a potential candidate to be repurposed as anti-glycation drug.

Synergistic Effect of Flavonoids and Metformin on Protection of the Methylglyoxal-Induced Damage in PC-12 Neuroblastoma Cells: Structure-Activity Relationship and Potential Target.

Methylglyoxal-induced ROS elevation is the primary cause of neuronal damage. Metformin is a traditional hypoglycemic drug that has been reported to be beneficial to the nervous system. In this study, flavonoids were found to enhance the protective effect of metformin when added at a molar concentration of 0.5%. The structure-activity relationship (SAR) analysis indicated that ortho- substitution in the B ring, and the absence of double bonds between the 2 and 3 position combined with the gallate substitution with R configuration at the 3 position in the C ring played crucial roles in the synergistic effects, which could be beneficial for designing a combination of the compounds. Additionally, the mechanism study revealed that a typical flavonoid, EGCG, enhanced ROS scavenging and anti-apoptotic ability via the BCL2/Bax/Cyto C/Caspase-3 pathway, and synergistically inhibited the expression of GSK-3β, BACE-1, and APP in PC-12 cells when used in combination with metformin. The dose of metformin used in the combination was only 1/4 of the conventional dose when used alone. These results suggested that ROS-mediated apoptosis and the pathways related to amyloid plaques (Aβ) formation can be the targets for the synergistic neuroprotective effects of flavonoids and metformin.

Pomegranate polyphenol punicalin ameliorates lipopolysaccharide-induced memory impairment, behavioral disorders, oxidative stress, and neuroinflammation via inhibition of TLR4-NF-кB pathway.

Neuroinflammation may play an important role in the development of Alzheimer's disease (AD). Previous studies have reported that lipopolysaccharide (LPS)-induced neuroinflammation causes memory impairments and behavioral disorders. We investigated the potential preventive effects of punicalin (PUN), a polyphenolic component of pomegranate, on LPS-induced memory deficiency and anxiety- and depression-like behaviors, along with the underlying mechanisms. LPS-treated cultured microglial BV2 cells and BV2 cell/Neuro-2a (N2a) cell coculture system were investigated for anti-neuroinflammatory effects of PUN in vitro. The in vivo experiments involved mice administered a 4-week course of oral gavage with 1500 mg/kg/d PUN before intraperitoneal LPS (250 mg/kg daily 7 times) injections. The in vitro results demonstrated that PUN inhibited the LPS-induced inflammatory cytokine (IL-18, IL-1β, TNF-ɑ, and IL-6) production in BV2 cells and protected N2a cells from synaptic damage mediated by BV2 microglia-induced neuroinflammation. In in vivo studies, it was observed that PUN improved memory impairment and anxiety- and depression-like behaviors caused by LPS and reduced the expression of inflammatory proteins such as iNOS, COX-2, IL-1β, IL-2, IL-6, and TNF-α. Furthermore, PUN inhibited the LPS-induced production of MDA; increased the activities of CAT, SOD, and GSH-Px, and inhibited LPS-induced Aβ1-42 generation through down-regulation of APP and BACE1 expression. Moreover, PUN also suppressed the expression of TLR4, IRAK4, TRAF6, IKK-β, NF-κB, p65, and HMGB1 in LPS-treated mouse brain and cultured microglial BV-2 cells. These results suggest that PUN inhibits LPS-induced memory impairment via anti-inflammatory and anti-amylogenic mechanisms through inhibition of TLR4-NF-kB activation.

Berberine alleviates Alzheimer's disease by regulating the gut microenvironment, restoring the gut barrier and brain-gut axis balance

BackgroundAlzheimer's disease (AD) is the most common neurodegenerative disease. Intestinal flora and its metabolism play a significant role in ameliorating central nervous system disorders, including AD, through bidirectional interactions between the gut-brain axis. A naturally occurring alkaloid compound called berberine (BBR) has neuroprotective properties and prevents Aβ-induced microglial activation. Additionally, BBR can suppress the synthesis of Aβ and decrease BACE1 expression. However, it is still unclear if BBR therapy can alleviate AD by changing the gut flora. PurposeIn this study, we examined whether a partial alleviation of AD could be achieved with BBR treatment and the molecular mechanisms involved. MethodsWe did this by analyzing alterations in Aβ plaques, neurons, and related neuroinflammation-related markers in the brain and the transcriptome of the mouse brain. The relationship between the intestinal flora of 5xFAD model mice and BBR treatment was investigated using high-throughput sequencing analysis of 16S rRNA from mouse feces. ResultsThe findings demonstrated that treatment with BBR cleared Aβ plaques, alleviated neuroinflammation, and ameliorated spatial memory dysfunction in AD. BBR significantly alleviated intestinal inflammation, decreased intestinal permeability, and could improve intestinal microbiota composition in 5xFAD mice.

Total ginsenosides decrease Aβ production through activating PPARγ

IntroductionTotal ginsenosides (TG), the major active constituents of ginseng, have been proven to be beneficial in treatment of Alzheimer’s disease (AD). However, the underlying mechanism of TG remains unclear. MethodsAPP/PS1 mice and N2a/APP695 cells were used as in vivo and in vitro model, respectively. Morris water maze (MWM) was used to investigate behavioral changes of mice; neuronal pathological changes were assessed by hematoxylin and eosin (H&E) and nissl staining; immunofluorescence staining was used to examine amyloid beta (Aβ) deposition; Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) were used to examine the expression of relative amyloidogenic genes and proteins. Moreover, the antagonist of PPARγ, GW9662, was used to determine whether the effects of TG on Aβ production were associated with PPARγ activity. ResultsTG treatment increased the spatial learning and memory abilities of APP/PS1 mice while decreasing the Aβ accumulation in the cortex and hippocampus. In N2a/APP695 cells, TG treatment attenuated the secretion of Aβ1–40 and Aβ1–42 acting as an PPARγ agonist by inhibiting the translocation of NF-κB p65. Additionally, TG treatment also decreased the expression of amyloidogenic pathway related gene BACE1, PS1 and PS2. ConclusionsTG treatment reduced the production of Aβ both in vivo and in vitro. Activating PPARγ might be a potential therapeutic target of TG in facilitating Aβ clearance and ameliorating cognitive deficiency in APP/PS1 mice.

Mechanism interpretation of Guhan Yangshengjing for protection against Alzheimer’s disease by network pharmacology and molecular docking

Ethnopharmacological relevanceGuhan Yangshengjing (GHYSJ) is an effective prescription for delaying progression of Alzheimer’s disease (AD) based on the ancient Chinese medical classics excavated from Mawangdui Han Tomb. Comprising a combination of eleven traditional Chinese herbs, the precise protective mechanism through which GHYSJ acts on AD progression remains unclear and has significant implications for the development of new drugs to treat AD. Aim of the studyTo investigate the mechanism of GHYSJ in the treatment of AD through network pharmacology and validate the results through in vitro experiments. Materials and methodsChemical composition-target-pathway network and protein-protein interaction network were constructed by network pharmacology to predict the potential targets of GHYSJ for the treatment of AD. The interaction relationship between active ingredients and targets was verified by molecular docking and molecular force. Furthermore, the chemical constituents of GHYSJ were analyzed by LC-MS and HPLC, the effects of GHYSJ on animal tissues were analyzed by H&E staining. An Aβ-induced SH-SY5Y cellular model was established to validate the core pathways and targets predicted by network pharmacology and molecular docking. ResultsThe results of the network pharmacology analysis revealed a total of 155 bioactive compounds capable of crossing the blood-brain barrier and interacting with 677 targets, among which 293 targets specifically associated with AD, which mainly participated in and regulated the amyloid aggregation pathway and PI3K/Akt signaling pathway, thereby treating AD. In addition, molecular docking analysis revealed a robust binding affinity between the principal bioactive constituents of GHYSJ and crucial targets implicated in AD. Our findings were further substantiated by in vitro experiments, which demonstrated that Liquiritigenin and Ginsenosides Rh4, crucial constituents of GHYSJ, as well as GHYSJ pharmaceutic serum, exhibited a significant down-regulation of BACE1 expression in Aβ-induced damaged SH-SY5Y cells. This study provides valuable data and theoretical underpinning for the potential therapeutic application of GHYSJ in the treatment of AD and secondary development of GHYSJ prescription. ConclusionThrough network pharmacology, molecular docking, LC-MS, and cellular experiments, GHYSJ was initially confirmed to delay the progression of AD by regulating the expression of BACE1 in Amyloid aggregation pathway. Our observations provided valuable data and theoretical underpinning for the potential therapeutic application of GHYSJ in the treatment of AD.

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.

Design, Synthesis, and Biological Investigation of Quinazoline Derivatives as Multitargeting Therapeutics in Alzheimer's Disease Therapy.

An efficient and promising method of treating complex neurodegenerative diseases like Alzheimer's disease (AD) is the multitarget-directed approach. Here in this work, a series of quinazoline derivatives (AV-1 to AV-21) were rationally designed, synthesized, and biologically evaluated as multitargeted directed ligands against human cholinesterase (hChE) and human β-secretase (hBACE-1) that exhibit moderate to good inhibitory effects. Compounds AV-1, AV-2, and AV-3 from the series demonstrated balanced and significant inhibition against these targets. These compounds also displayed excellent blood-brain barrier permeability via the PAMPA-BBB assay. Compound AV-2 significantly displaced propidium iodide (PI) from the acetylcholinesterase-peripheral anionic site (AChE-PAS) and was found to be non-neurotoxic at the maximum tested concentration (80 μM) against differentiated SH-SY5Y cell lines. Compound AV-2 also prevented AChE- and self-induced Aβ aggregation in the thioflavin T assay. Additionally, compound AV-2 significantly ameliorated scopolamine and Aβ-induced cognitive impairments in the in vivo behavioral Y-maze and Morris water maze studies, respectively. The ex vivo and biochemical analysis further revealed good hippocampal AChE inhibition and the antioxidant potential of the compound AV-2. Western blot and immunohistochemical (IHC) analysis of hippocampal brain revealed reduced Aβ, BACE-1, APP/Aβ, and Tau molecular protein expressions levels. The pharmacokinetic analysis of compound AV-2 demonstrated significant oral absorption with good bioavailability. The in silico molecular modeling studies of lead compound AV-2 moreover demonstrated a reasonable binding profile with AChE and BACE-1 enzymes and stable ligand-protein complexes throughout the 100 ns run. Compound AV-2 can be regarded as the lead candidate and could be explored more for AD therapy.

Abnormal amyloid precursor protein processing in periodontal tissue in a murine model of periodontitis induced by Porphyromonas gingivalis.

The study aimed to investigate the change of amyloid precursor protein (APP) processing and amyloid β (Aβ) metabolites in linking periodontitis to Alzheimer's disease (AD). Aβ is one of the main pathological features of AD, and few studies have discussed changes in its expression in peripheral tissues or analyzed the relationship between the peripheral imbalance of Aβ production and clearance. A murine model of periodontitis was established by oral infection with Porphyromonas gingivalis (P. gingivalis). Micro-computed tomography (Micro-CT) was used to observe the destruction of the alveolar bone. Nested quantitative polymerase chain reaction (qPCR) was used to measure small quantities of P.gingivalis DNA in different tissues. Behavioral experiments were performed to measure cognitive function in the mice. The mRNA levels of TNF-α, IL-6, IL-8, RANKL, OPG, APP695, APP751, APP770, and BACE1 in the gingival tissues or cortex were detected by RT-PCR. The levels of Aβ1-40 and Aβ1-42 in gingival crevicular fluid (GCF) and plasma were tested by ELISA. P. gingivalis oral infection was found to cause alveolar bone resorption and impaired learning and memory. P.gingivalis DNA was detected in the gingiva, blood and cortex of the P.gingivalis group by nested qPCR (p < .05). The mRNA expression of TNF-α, IL-6, IL-8, RANKL/OPG, and BACE1 in the gingival tissue was significantly higher than that in the control group (p < .05). Similarly, upregulated mRNA levels of APP695 and APP770 were observed in the gingival tissuses and cortex of the P. gingivalis group (p < .05). The levels of Aβ1-40 and Aβ1-42 in the GCF and plasma of the P. gingivalis group were significantly higher than those in the control group (p < .05). P. gingivalis can directly invade the brain via hematogenous infection. The invasion of P. gingivalis could trigger an immune response and lead to an imbalance between Aβ production and clearance in peripheral tissues, which may trigger an abnormal Aβ metabolite in the brain, resulting in the occurrence and development of AD.

Hyperthyroidism-Induced Upregulation of Neurodegeneration-Related Gene Expression in Metaplasticity-Induced Hippocampus

Introduction: Thyroid hormones, which produce critical changes in our bodies even when their physiological levels alter slightly, are crucial hormones that influence gene transcription. Neuronal plasticity, on the other hand, requires both the activation of local proteins as well as protein translation and transcription in response to external signals. So far, no study has examined metaplastic long-term potentiation (LTP) and related gene expression levels in a hyperthyroid experimental model. Methods: The Wistar male rats were administered 0.2 mg/kg/day of <sc>l</sc>-thyroxine for 21 days to induce hyperthyroidism. Perforant path was primed with 1-Hz low-frequency stimuli (LFS) for 900 s to investigate metaplasticity responses. The LFS was followed by high-frequency stimuli (HFS, 100 Hz) after 5 min. Excitatory postsynaptic potential (EPSP) slope and population spike (PS) amplitude were recorded from the granule cell layer of the dentate gyrus. The mRNA levels of genes related to neurodegeneration (Gsk-3β, Cdk5, Akt1, Mapt, p35, Capn1, Bace1, and Psen2) were measured using the RT-PCR method for the stimulated hippocampus. Results: Similar to euthyroid rats, hyperthyroid animals had a lower EPSP slope and PS after LFS. Depression of EPSP prevented subsequently induced EPSP-LTP, although HFS was able to elicit PS-LTP despite depression of PS amplitude in both groups. Despite similarities in metaplastic LTP responses, these electrophysiological findings were accompanied by increased Akt, Bace1, Cdk5, and p35-mRNA expressions and decreased Gsk-3β mRNA expression in hyperthyroid rats’ hippocampus. Conclusion: These data support the view that in thyroid hormone excess, the mechanism that keeps synaptic efficacy within a dynamic range occurs concurrently with increased mRNA expression of neurodegeneration-related genes. Our study encourages further examination of the increased risk of neurodegenerative disease in hyperthyroidism.