Role of p38/MAPKs in Alzheimer's disease: implications for amyloid beta toxicity targeted therapy

p38 MAPK inhibitor SB202190 suppresses ferroptosis in the glutamate-induced retinal excitotoxicity glaucoma model

JOURNAL/nrgr/04.03/01300535-202410000-00031/figure1/v/2024-02-06T055622Z/r/image-tiff Glutamate excitotoxicity has been shown to play an important role in glaucoma, and glutamate can induce ferroptosis. The p38 mitogen-activated protein kinase (MAPK) pathway inhibitor SB202190 has a potential ability to suppress ferroptosis, and its downstream targets, such as p53, have been shown to be associated with ferroptosis. However, whether ferroptosis also occurs in retinal ganglion cells in response to glutamate excitotoxicity and whether inhibition of ferroptosis reduces the loss of retinal ganglion cells induced by glutamate excitotoxicity remain unclear. This study investigated ferroptosis in a glutamate-induced glaucoma rat model and explored the effects and molecular mechanisms of SB202190 on retinal ganglion cells. A glutamate-induced excitotoxicity model in R28 cells and an N-methyl-D-aspartate-induced glaucoma model in rats were used. In vitro experiments showed that glutamate induced the accumulation of iron and lipid peroxide and morphological changes of mitochondria in R28 cells, and SB202190 inhibited these changes. Glutamate induced the levels of p-p38 MAPK/p38 MAPK and SAT1 and decreased the expression levels of ferritin light chain, SLC7A11, and GPX4. SB202190 inhibited the expression of iron death-related proteins induced by glutamate. In vivo experiments showed that SB202190 attenuated N-methyl-D-aspartate-induced damage to rat retinal ganglion cells and improved visual function. These results suggest that SB202190 can inhibit ferroptosis and protect retinal ganglion cells by regulating ferritin light chain, SAT1, and SLC7A11/Gpx4 pathways and may represent a potential retina protectant.

Exploring the Therapeutic Potential of BBB-Penetrating Phytochemicals With p38 MAPK Modulatory Activity in Addressing Oxidative Stress-Induced Neurodegenerative Disorders, With a Focus on Alzheimer's Disease

Oxidative stress plays an important role in the occurrence of neurodegenerative diseases. Previous studies indicate a strong connection between oxidative stress, inappropriate activation of the p38 MAPK signaling pathway, and the pathogenesis of neurodegenerative diseases. Although antioxidant therapy is a valid strategy to alleviate these problems, the most important limitation of this approach is the ineffectiveness of drug administration due to the limited permeability of the BBB. Therefore, BBB-penetrating p38 MAPK modulators with proper antioxidant capacity could be useful in preventing/reducing the complications of neurodegenerative disorders. The current manuscript aims to review the therapeutic capabilities of some recently reviewed naturally occurring p38 MAPK inhibitors in the management of neurodegenerative problems such as Alzheimer's disease. In data collection, we tried to use more recent studies published in high-quality journals indexed in databases Scopus, Web of Science, PubMed, and so on, but no specific time frame was considered due to the nature of the study. Our evaluations indicate that natural compounds tanshinones, protoberberines, pinocembrin, osthole, rhynchophylline, oxymatrine, schisandrin, piperine, paeonol, ferulic acid, 6-gingerol, obovatol, and trolox have significant potential for use as supplements/adjuvants in the reduction of neurodegenerative-related problems. Our findings emphasize the usefulness of BBB-penetrating phytochemicals with p38 MAPK modulatory activity as potential therapeutic options against neurodegenerative disorders. Of course, the proper use of these compounds depends on considering their toxicity/safety profile and pharmacokinetic characteristics as well as the clinical conditions of users.

Evolving significance of kinase inhibitors in the management of Alzheimer's disease

Alzheimer's disease is a neurodegenerative problem with progressive loss of memory and other cognitive function disorders resulting in the imbalance of neurotransmitter activity and signaling progression, which poses the need of the potential therapeutic target to improve the intracellular signaling cascade brought by kinases. Protein kinase plays a significant and multifaceted role in the treatment of Alzheimer's disease, by targeting pathological mechanisms like tau hyperphosphorylation, neuroinflammation, amyloid-beta production and synaptic dysfunction. In this review, we thoroughly explore the essential protein kinases involved in Alzheimer's disease, detailing their physiological roles, regulatory impacts, and the newest inhibitors and compounds that are progressing into clinical trials. All the findings of studies exhibited the promising role of kinase inhibitors in the management of Alzheimer's disease. However, it still poses the need of addressing current challenges and opportunities involved with this disorder for the future perspective of kinase inhibitors in the management of Alzheimer's disease. Further study includes the development of biomarkers, combination therapy, and next-generation kinase inhibitors with increased potency and selectivity for its future prospects.

Pathogenesis, diagnostics, and therapeutics for Alzheimer's disease: Breaking the memory barrier

Alzheimer's disease (AD) is the most common cause of dementia and accounts for 60-70 % of all cases. It affects millions of people worldwide. AD poses a substantial economic burden on societies and healthcare systems. AD is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and impaired daily functioning. As the prevalence of AD continues to increase, understanding its pathogenesis, improving diagnostic methods, and developing effective therapeutics have become paramount. This comprehensive review delves into the intricate mechanisms underlying AD, explores the current state of diagnostic techniques, and examines emerging therapeutic strategies. By revealing the complexities of AD, this review aims to contribute to the growing body of knowledge surrounding this devastating disease.

Ferroptosis: A new strategy for targeting Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a complex pathogenesis, which involves the formation of amyloid plaques and neurofibrillary tangles. Many recent studies have revealed a close association between ferroptosis and the pathogenesis of AD. Factors such as ferroptosis-associated iron overload, lipid peroxidation, disturbances in redox homeostasis, and accumulation of reactive oxygen species have been found to contribute to the pathological progression of AD. In this review, we explore the mechanisms underlying ferroptosis, describe the link between ferroptosis and AD, and examine the reported efficacy of ferroptosis inhibitors in treating AD. Finally, we discuss the potential challenges to ferroptosis inhibitors use in the clinic, enabling their faster use in clinical treatment.

Polysaccharides extracted from common buckwheat (Fagopyrum esculentum) attenuate cognitive impairment via suppressing RAGE/p38/NF-κB signaling and dysbiosis in AlCl3-treated rats

Patients may find it challenging to accept several FDA-approved drugs for Alzheimer's disease (AD) treatment due to their unaffordable prices and side effects. Despite the known antioxidant, anti-inflammatory, and microbiota-regulating effects of common buckwheat (Fagopyrum esculentum) polysaccharides (FEP), their specific role in preventing AD has not been determined. Here, this study investigated the preventive effects of FEP on AD development in AlCl3-treated rats. The physical properties of FEP were evaluated using X-ray diffraction, FTIR, TGA, DSC, monosaccharide composition, molecular weight, and scanning electron microscopy. The results demonstrated that FEP administration improved memory and learning ability in AlCl3-treated rats. Additionally, AD pathological biomarkers (APP, BACE1, Aβ1-42, and p-TauSer404), inflammatory-associated proteins (IL-1β, IL-6, TNF-α, and Iba1), and MDA and the RAGE/p38/NF-κB pathway were elevated in AlCl3-treated rats. Moreover, these effects were reversed by the upregulation of LRP1, anti-inflammatory cytokines (IL-4 and IL-10), antioxidant enzymes (SOD and catalase), and autophagy proteins (Atg5, Beclin-1, and LC3B). Furthermore, FEP treatment increased the levels of short-chain fatty acids (SCFAs) and the abundance of SCFAs-producing microbes ([Eubacterium]_xylanophilum_group, Lachnospiraceae_NK4A136_group, Lactobacillus). Overall, FEP mitigated oxidative stress, RAGE/p38/NF-κB-mediated neuroinflammation, and AD-associated proteins by upregulating autophagy and SCFA levels, which led to the amelioration of cognitive impairment through microbiota-gut-brain communication in AlCl3-treated rats.

Inhibition of the P38 MAPK/NLRP3 pathway mitigates cognitive dysfunction and mood alterations in aged mice after abdominal surgery plus sevoflurane

BACKGROUND

Cognitive dysfunction, encompassing perioperative psychological distress and cognitive impairment, is a prevalent postoperative complication within the elderly population, and in severe cases, it may lead to dementia. Building upon our prior research that unveiled a connection between postoperative mood fluctuations and cognitive dysfunction with the phosphorylation of P38, this present investigation aims to delve deeper into the involvement of the P38 MAPK/NLRP3 pathway in perioperative neurocognitive disorders (PND) in an abdominal exploratory laparotomy (AEL) aged mice model.

METHODS

C57BL/6 mice (male, 18-month-old) underwent AEL with 3 % anesthesia. Then, inhibitors targeting P38 MAPK (SB202190, 1 mg/kg) and GSK3β (TWS119, 10 mg/kg) were administered multiple times daily for 7 days post-surgery. The NLRP3-cKO AEL and WT AEL groups only underwent the AEL procedure. Behavioral assessments, including the open field test (OFT), novel object recognition (NOR), force swimming test (FST), and fear conditioning (FC), were initiated on postoperative day 14. Additionally, mice designated for neuroelectrophysiological monitoring had electrodes implanted on day 14 before surgery and underwent novel object recognition while their local field potential (LFP) was concurrently recorded on postoperative day 14. Lastly, after they were euthanasized, pathological analysis and western blot were performed.

RESULTS

SB202190, TWS119, and astrocyte-conditional knockout NLRP3 all ameliorated the cognitive impairment behaviors induced by AEL in mice and increased mean theta power during novel location exploration. However, it is worth noting that SB202190 may exacerbate postoperative depressive and anxiety-like behaviors in mice, while TWS119 may induce impulsive behaviors.

CONCLUSIONS

Our study suggests that anesthesia and surgical procedures induce alterations in mood and cognition, which may be intricately linked to the P38 MAPK/NLRP3 pathway.

The duality of amyloid-β: its role in normal and Alzheimer's disease states

Alzheimer's disease (AD) is a degenerative neurological condition that gradually impairs cognitive abilities, disrupts memory retention, and impedes daily functioning by impacting the cells of the brain. A key characteristic of AD is the accumulation of amyloid-beta (Aβ) plaques, which play pivotal roles in disease progression. These plaques initiate a cascade of events including neuroinflammation, synaptic dysfunction, tau pathology, oxidative stress, impaired protein clearance, mitochondrial dysfunction, and disrupted calcium homeostasis. Aβ accumulation is also closely associated with other hallmark features of AD, underscoring its significance. Aβ is generated through cleavage of the amyloid precursor protein (APP) and plays a dual role depending on its processing pathway. The non-amyloidogenic pathway reduces Aβ production and has neuroprotective and anti-inflammatory effects, whereas the amyloidogenic pathway leads to the production of Aβ peptides, including Aβ40 and Aβ42, which contribute to neurodegeneration and toxic effects in AD. Understanding the multifaceted role of Aβ, particularly in AD, is crucial for developing effective therapeutic strategies that target Aβ metabolism, aggregation, and clearance with the aim of mitigating the detrimental consequences of the disease. This review aims to explore the mechanisms and functions of Aβ under normal and abnormal conditions, particularly in AD, by examining both its beneficial and detrimental effects.

Residual Microglia Following Short-term PLX5622 Treatment in 5xFAD Mice Exhibit Diminished NLRP3 Inflammasome and mTOR Signaling, and Enhanced Autophagy

Chronic neuroinflammation represents a prominent hallmark of Alzheimer's disease (AD). While moderately activated microglia are pivotal in clearing amyloid beta (Aβ), hyperactivated microglia perpetuate neuroinflammation. Prior investigations have indicated that the elimination of ∼80% of microglia through a month-long inhibition of the colony-stimulating factor 1 receptor (CSF1R) during the advanced stage of neuroinflammation in 5xFamilial AD (5xFAD) mice mitigates synapse loss and neurodegeneration without impacting Aβ levels. Furthermore, prolonged CSF1R inhibition diminished the development of parenchymal plaques. Nonetheless, the immediate effects of short-term CSF1R inhibition during the early stages of neuroinflammation on residual microglial phenotype or metabolic fitness are unknown. Therefore, we investigated the effects of 10-day CSF1R inhibition in three-month-old female 5xFAD mice, a stage characterized by the onset of neuroinflammation and minimal Aβ plaques. We observed ∼65% microglia depletion in the hippocampus and cerebral cortex. The leftover microglia demonstrated a noninflammatory phenotype, with highly branched and ramified processes and reduced NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome complexes. Moreover, plaque-associated microglia were reduced in number with diminished Clec7a (dectin-1) expression. Additionally, both microglia and neurons displayed reduced mechanistic target of rapamycin (mTOR) signaling and autophagy. Biochemical assays validated the inhibition of NLRP3 inflammasome activation, decreased mTOR signaling, and enhanced autophagy. However, short-term CSF1R inhibition did not influence Aβ plaques, soluble Aβ-42 levels, or hippocampal neurogenesis. Thus, short-term CSF1R inhibition during the early stages of neuroinflammation in 5xFAD mice promotes the retention of homeostatic microglia with diminished inflammasome activation and mTOR signaling, alongside increased autophagy.

Embelin Mitigates Amyloid-β-Induced Neurotoxicity and Cognitive Impairment in Rats: Potential Therapeutic Implications for Alzheimer's Disease

Alzheimer's disease (AD) is a significant form of dementia. Embelin (EMB) is a natural compound with varied actions that could help prevent AD pathology. Herein, we have investigated the neuroprotective potential of EMB against Aβ1-42-induced neurotoxicity in rats. In this experiment, Alzheimer-like dementia was induced in rats by infusing Aβ1-42 oligomers directly into the brain's ventricles. Subsequently, the Aβ1-42-intoxicated rats received treatment with varying doses of EMB (2.5, 5, and 10 mg/kg, administered intraperitoneally) over 2 weeks. The spatial and non-spatial memory of animals was assessed at different time intervals, and various biochemical, neurochemical, and neuroinflammatory parameters in the hippocampal brain tissue of the rats were analyzed. Infusion of Aβ1-42 in rat brain caused cognitive impairment and was accompanied by increased acetylcholinesterase activity, oxidative stress, and elevated levels of pro-inflammatory cytokines (such as TNF-α, IL-1β, and IL-6) in the hippocampal tissue. Moreover, a significant decline in the levels of monoamines and an imbalance of GABA and glutamate levels were also observed. EMB treatment significantly mitigated Aβ1-42-induced cognitive deficit and other biochemical changes, including Aβ levels. The EMB-treated rats showed improved learning and consolidation of memory. EMB also attenuated Aβ-induced oxidative stress and neuroinflammation and restored the levels of monoamines and the balance between GABA and glutamate. The observed cognitive benefits following EMB treatment in Aβ1-42-infused rats may be attributed to its antioxidant and anti-inflammatory properties and ability to restore hippocampal neurochemistry and Aβ levels. The above findings indicate the therapeutic potential of EMB in neurodegenerative pathologies associated with cognitive decline, such as Alzheimer's disease.

Ribonucleotide reductase inhibition improves the symptoms of a Caenorhabditis elegans model of Alzheimer's disease

Alzheimer's disease is the main cause of aging-associated dementia, for which there is no effective treatment. In this work, we reanalyze the information of a previous genome wide association study, using a new pipeline design to identify novel potential drugs. With this approach, ribonucleoside-diphosphate reductase gene (RRM2B) emerged as a candidate target and its inhibitor, 2', 2'-difluoro 2'deoxycytidine (gemcitabine), as a potential pharmaceutical drug against Alzheimer's disease. We functionally verified the effect of inhibiting the RRM2B homolog, rnr-2, in an Alzheimer's model of Caenorhabditis elegans, which accumulates human Aβ1-42 peptide to an irreversible paralysis. RNA interference against rnr-2 and also treatment with 200 ng/ml of gemcitabine, showed an improvement of the phenotype. Gemcitabine treatment increased the intracellular ATP level 3.03 times, which may point to its mechanism of action. Gemcitabine has been extensively used in humans for cancer treatment but at higher concentrations. The 200 ng/ml concentration did not exert a significant effect over cell cycle, or affected cell viability when assayed in the microglia N13 cell line. Thus, the inhibitory drug of the RRM2B activity could be of potential use to treat Alzheimer's disease and particularly gemcitabine might be considered as a promising candidate to be repurposed for its treatment.

Polyphenols Targeting MAP Kinase Signaling Pathway in Neurological Diseases: Understanding Molecular Mechanisms and Therapeutic Targets

Polyphenols are a class of secondary metabolic products found in plants that have been extensively studied for how well they regulate biological processes, such as the proliferation of cells, autophagy, and apoptosis. The mitogen-activated protein kinase (MAPK)-mediated signaling cascade is currently identified as a crucial pro-inflammatory pathway that plays a significant role in the development of neuroinflammation. This process has been shown to contribute to the pathogenesis of several neurological conditions, such as Alzheimer's disease (AD), Parkinson's disease (PD), CNS damage, and cerebral ischemia. Getting enough polyphenols through eating habits has resulted in mitigating the effects of oxidative stress (OS) and lowering the susceptibility to associated neurodegenerative disorders, including but not limited to multiple sclerosis (MS), AD, stroke, and PD. Polyphenols possess significant promise in dealing with the root cause of neurological conditions by modulating multiple therapeutic targets simultaneously, thereby attenuating their complicated physiology. Several polyphenolic substances have demonstrated beneficial results in various studies and are presently undergoing clinical investigation to treat neurological diseases (NDs). The objective of this review is to provide a comprehensive summary of the different aspects of the MAPK pathway involved in neurological conditions, along with an appraisal of the progress made in using polyphenols to regulate the MAPK signaling system to facilitate the management of NDs.

Potential Alzheimer's disease drug targets identified through microglial biology research

INTRODUCTION

Microglia, the primary immune cells in the brain, play multifaceted roles in Alzheimer's disease (AD). Microglia can potentially mitigate the pathological progression of AD by clearing amyloid beta (Aβ) deposits in the brain and through neurotrophic support. In contrast, disproportionate activation of microglial pro-inflammatory pathways, as well as excessive elimination of healthy synapses, can exacerbate neurodegeneration in AD. The challenge, therefore, lies in discerning the precise regulation of the contrasting microglial properties to harness their therapeutic potential in AD.

AREAS COVERED

This review examines the evidence relevant to the disease-modifying effects of microglial manipulators in AD preclinical models. The deleterious pro-inflammatory effects of microglia in AD can be ameliorated via direct suppression or indirectly through metabolic manipulation, epigenetic targeting, and modulation of the gut-brain axis. Furthermore, microglial clearance of Aβ deposits in AD can be enhanced via strategically targeting microglial membrane receptors, lysosomal functions, and metabolism.

EXPERT OPINION

Given the intricate and diverse nature of microglial responses throughout the course of AD, therapeutic interventions directed at microglia warrant a tactical approach. This could entail employing therapeutic regimens, which concomitantly suppress pro-inflammatory microglial responses while selectively enhancing Aβ phagocytosis.

Exploring Acori Tatarinowii Rhizoma and Polygalae Radix in Alzheimer's: Network pharmacology and molecular docking analysis

Explore Acori Tatarinowii Rhizoma (ATR) and Polygalae Radix (PR) mechanisms in Alzheimer's disease (AD) treatment through network pharmacology. ATR-PR was investigated in the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, Batman, and Traditional Chinese Medicines Integrated Database (TCMID) to gather information on its chemical components and target proteins. Target genes associated with AD were retrieved from the GeneCards and National Center for Biotechnology Information (NCBI) databases. The integration of these datasets with potential targets facilitated the construction of an AD and ATR-PR protein-protein interaction (PPI) network using the STRING database. The resulting network identified the core active ingredients and main targets of ATR-PR in AD treatment. Cluster analysis of the PPI network was performed using Cytoscape 3.7.1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the Metascape database. Molecular docking simulations revealed potential interactions between the main active ingredients and core targets. Our analysis identified 8 putative components and 455 targets of ATR-PR. We systematically searched for 1306 genes associated with AD, conducted Venn diagram analysis resulting in 156 common targets, and constructed a PPI network with 57 key targets. GO functional analysis highlighted the primary biological processes associated with oxidative stress. KEGG pathway enrichment analysis revealed the involvement of 64 signaling pathways, with the PI3K/Akt signaling pathway playing a key role. Molecular docking analysis indicated a high affinity between the potential targets of ATR-PR and the main compounds of AD. This study sheds light on the complex network of interactions involving ATR-PR in the context of AD. The identified targets, pathways, and interactions provide a foundation for understanding the potential therapeutic mechanisms. The involvement of oxidative stress-related processes and the crucial role of the PI3K/Akt signaling pathway suggest avenues for targeted therapeutic interventions in Alzheimer's disease treatment. Our proposition of the combined use of ATR-PR has emerged as a potential treatment strategy for AD, supported by a network pharmacology approach. This framework provides a robust foundation for future clinical applications and experimental research in the pursuit of effective Alzheimer's disease treatments.

Acanthopanax senticosus improves cognitive impairment in Alzheimer's disease by promoting the phosphorylation of the MAPK signaling pathway

Background

Acanthopanax senticosus (AS) can improve sleep, enhance memory, and reduce fatigue and is considered as an effective drug for Alzheimer's disease (AD). The therapeutic effect and mechanism need to be further investigated.

Methods

To confirm the AS play efficacy in alleviating memory impairment in mice, 5×FAD transgenic mice were subjected to an open-field experiment and a novelty recognition experiment. Network pharmacology technique was used to analyze the information of key compounds and potential key targets of AS for the treatment of AD, molecular docking technique was applied to predict the binding ability of targets and compounds, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were also performed on the targets to derive the possible metabolic processes and pathway mechanisms of AS in treating AD. Quantitative real-time PCR (qRT-PCR) and western blot technique were carried out to validate the candidate genes and pathways.

Results

In the open-field experiment, compared with the wild-type (WT) group, the number of times the mice in the AD group crossed the central zone was significantly reduced (P< 0.01). Compared with the AD group, the number of times the mice in the AS group crossed the central zone was significantly increased (P< 0.001). In the new object recognition experiment, compared with the WT group, the percentage of times the AD group explored new objects was significantly reduced (P< 0.05). Compared with the AD group, the AS group had an increase in the percentage of time spent exploring new things and the number of times it was explored (P< 0.05). At the same time, the donepezil group had a significantly higher percentage of times exploring new things (P< 0.01). By using network pharmacology technology, 395 common targets of AS and AD were retrieved. The Cytoscape software was used to construct the protein-protein interaction (PPI) network of common targets. Using the algorithm, nine key targets were retrieved: APP, NTRK1, ESR1, CFTR, CSNK2A1, EGFR, ESR2, GSK3B, and PAK1. The results of molecular docking indicate that 11 pairs of compounds and their corresponding targets have a significant binding ability, as the molecular binding energies were less than -7.0. In comparison to the AD group, the mRNA expression of the key target genes was significantly decreased in the AS treatment group (P< 0.001). The KEGG analysis showed that the MAPK signaling pathway was significantly enriched, and Western blot confirmed that the TRAF6 protein decreased significantly (P< 0.0001). Meanwhile, the levels of MAP3K7 and P38 phosphorylation increased, and there was also an increase in the expression of HSP27 proteins.

Conclusion

Our study indicates that the multi-component and multi-target properties of AS play an important role in the alleviation of anxiety and memory impairment caused by AD, and the mechanism is involved in the phosphorylation and activation of the MAPK signaling pathway. The results of this study could provide a novel perspective for the clinical treatment of AD.

Effects of Cerebrospinal Fluids from Alzheimer and Non-Alzheimer Patients on Neurons-Astrocytes-Microglia Co-Culture

Alzheimer's disease (AD) is the most common form of dementia, characterized by the accumulation of β-amyloid plaques, tau tangles, neuroinflammation, and synaptic/neuronal loss, the latter being the strongest correlating factor with memory and cognitive impairment. Through an in vitro study on a neurons-astrocytes-microglia (NAM) co-culture system, we analyzed the effects of cerebrospinal fluid (CSF) samples from AD and non-AD patients (other neurodegenerative pathologies). Treatment with CSF from AD patients showed a loss of neurofilaments and spheroids, suggesting the presence of elements including CX3CL1 (soluble form), destabilizing the neurofilaments, cellular adhesion processes, and intercellular contacts. The NAM co-cultures were analyzed in immunofluorescence assays for several markers related to AD, such as through zymography, where the expression of proteolytic enzymes was quantified both in cell extracts and the co-cultures' conditioned medium (CM). Through qRT-PCR assays, several genes involved in the formation of β-amyloid plaque, in phosphorylation of tau, and in inflammation pathways and MMP expression were investigated.

Function and inhibition of P38 MAP kinase signaling: Targeting multiple inflammation diseases

Inflammation is a natural host defense mechanism that protects the body from pathogenic microorganisms. A growing body of research suggests that inflammation is a key factor in triggering other diseases (lung injury, rheumatoid arthritis, etc.). However, there is no consensus on the complex mechanism of inflammatory response, which may include enzyme activation, mediator release, and tissue repair. In recent years, p38 MAPK, a member of the MAPKs family, has attracted much attention as a central target for the treatment of inflammatory diseases. However, many p38 MAPK inhibitors attempting to obtain marketing approval have failed at the clinical trial stage due to selectivity and/or toxicity issues. In this paper, we discuss the mechanism of p38 MAPK in regulating inflammatory response and its key role in major inflammatory diseases and summarize the synthetic or natural products targeting p38 MAPK to improve the inflammatory response in the last five years, which will provide ideas for the development of novel clinical anti-inflammatory drugs based on p38 MAPK inhibitors.

Intranasally Administered EVs from hiPSC-derived NSCs Alter the Transcriptomic Profile of Activated Microglia and Conserve Brain Function in an Alzheimer's Model

Antiinflammatory extracellular vesicles (EVs) derived from human induced pluripotent stem cell (hiPSC)-derived neural stem cells (NSCs) hold promise as a disease-modifying biologic for Alzheimer's disease (AD). This study directly addressed this issue by examining the effects of intranasal administrations of hiPSC-NSC-EVs to 3-month-old 5xFAD mice. The EVs were internalized by all microglia, which led to reduced expression of multiple genes associated with disease-associated microglia, inflammasome, and interferon-1 signaling. Furthermore, the effects of hiPSC-NSC-EVs persisted for two months post-treatment in the hippocampus, evident from reduced microglial clusters, inflammasome complexes, and expression of proteins and/or genes linked to the activation of inflammasomes, p38/mitogen-activated protein kinase, and interferon-1 signaling. The amyloid-beta (Aβ) plaques, Aβ-42, and phosphorylated-tau concentrations were also diminished, leading to better cognitive and mood function in 5xFAD mice. Thus, early intervention with hiPSC-NSC-EVs in AD may help maintain better brain function by restraining the progression of adverse neuroinflammatory signaling cascades.

Regulation of neuroinflammation in Alzheimer's disease via nanoparticle-loaded phytocompounds with anti-inflammatory and autophagy-inducing properties

BACKGROUND

Alzheimer's disease (AD) is characterized by neuroinflammation linked to amyloid β (Aβ) aggregation and phosphorylated tau (τ) protein in neurofibrillary tangles (NFTs). Key elements in Aβ production and NFT assembly, like γ-secretase and p38 mitogen-activated protein kinase (p38MAPK), contribute to neuroinflammation. In addition, impaired proteosomal and autophagic pathways increase Aβ and τ aggregation, leading to neuronal damage. Conventional neuroinflammation drugs have limitations due to unidirectional therapeutic approaches and challenges in crossing the Blood-Brain Barrier (BBB). Clinical trials for non-steroidal anti-inflammatory drugs (NSAIDs) and other therapeutics remain uncertain. Novel strategies addressing the complex pathogenesis and BBB translocation are needed to effectively tackle AD-related neuroinflammation.

PURPOSE

The current scenario demands for a much-sophisticated theranostic measures which could be achieved via customized engineering and designing of novel nanotherapeutics. As, these therapeutics functions as a double edge sword, having the efficiency of unambiguous targeting, multiple drug delivery and ability to cross BBB proficiently.

METHODS

Inclusion criteria involve selecting recent, English-language studies from the past decade (2013-2023) that explore the regulation of neuroinflammation in neuroinflammation, Alzheimer's disease, amyloid β, tau protein, nanoparticles, autophagy, and phytocompounds. Various study types, including clinical trials, experiments, and reviews, were considered. Exclusion criteria comprised non-relevant publication types, studies unrelated to Alzheimer's disease or phytocompounds, those with methodological flaws, duplicates, and studies with inaccessible data.

RESULTS

In this study, polymeric nanoparticles loaded with specific phytocompounds and coated with an antibody targeting the transferrin receptor (anti-TfR) present on BBB. Thereafter, the engineered nanoparticles with the ability to efficiently traverse the BBB and interact with target molecules within the brain, could induce autophagy, a cellular process crucial for neuronal health, and exhibit potent anti-inflammatory effects. Henceforth, the proposed combination of desired phytocompounds, polymeric nanoparticles, and anti-TfR coating presents a promising approach for targeted drug delivery to the brain, with potential implications in neuroinflammatory conditions such as Alzheimer's disease.

Isolinderalactone Ameliorates the Pathology of Alzheimer's Disease by Inhibiting the JNK Signaling Pathway

Neuronal cell damage is a major cause of cognitive impairment in Alzheimer's disease (AD). Multiple factors, such as amyloid deposition, tau hyperphosphorylation, and neuroinflammation, can lead to neuronal cell damage. Therefore, the development of multi-target drugs with broad neuroprotective effects may be an effective strategy for the treatment of AD. Natural products have become an important source of drug discovery because of their good pharmacological activity, multiple targets, and low toxicity. In this study, we screened a natural compound library and found that the fat-soluble sesquiterpene natural compound isolinderalactone (Iso) extracted from the dried root pieces of Lindera aggregata had the ability to alleviate cellular damage induced by β-amyloid-1-42 (Aβ1-42). The role and mechanism of Iso in AD have not yet been reported. Herein, we demonstrated that Iso significantly reduced the level of apoptosis in PC12 cells. Besides, Iso treatment reduced amyloid deposition, neuron apoptosis, and neuroinflammation, ultimately improving the cognitive dysfunction of APP/PS1 (APPswe/PSEN 1dE9) mice. Notably, Iso-10 mg/kg showed superior improved effects in APP/PS1 mice compared with the positive control drug donepezil-5 mg/kg. Mechanistically, the results of RNA sequencing combined with Western blots showed that Iso exerted its therapeutic effect by inhibiting the c-Jun N-terminal kinase (JNK) signaling pathway. Taken together, our findings suggest that Iso is a potential drug candidate for the treatment of AD.

Alzheimer's Disease-Related Proteins Targeted by Secondary Metabolite Compounds from Streptomyces: A Scoping Review

Background

Alzheimer's disease (AD) is a neurodegenerative disease that is characterized as rapid and progressive cognitive decline affecting 26 million people worldwide. Although immunotherapies are ideal, its clinical safety and effectiveness are controversial, hence, treatments are still reliant on symptomatic medications. Concurrently, the Streptomyces genus has attracted attention given its pharmaceutically beneficial secondary metabolites to treat neurodegenerative diseases.

Objective

To present secondary metabolites from Streptomyces sp. with regulatory effects on proteins and identified prospective target proteins for AD treatment.

Methods

Research articles published between 2010 and 2021 were collected from five databases and 83 relevant research articles were identified. Post-screening, only 12 research articles on AD-related proteins were selected for further review. Bioinformatics analyses were performed through the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) network, PANTHER Go-Slim classification system (PANTHER17.0), and Kyoto Encyclopedia of Genes and Genomes (KEGG) Mapper.

Results

A total of 20 target proteins were identified from the 12 shortlisted articles. Amyloid-β, BACE1, Nrf-2, Beclin-1, and ATG5 were identified as the potential target proteins, given their role in initiating AD, mitigating neuroinflammation, and autophagy. Besides, 10 compounds from Streptomyces sp., including rapamycin, alborixin, enterocin, bonnevillamides D and E, caniferolide A, anhydroexfoliamycin, rhizolutin, streptocyclinone A and B, were identified to exhibit considerable regulatory effects on these target proteins.

Conclusions

The review highlights several prospective target proteins that can be regulated through treatments with Streptomyces sp. compounds to prevent AD's early stages and progression. Further identification of Streptomyces sp. compounds with potential anti-AD properties is recommended.

Evaluation of Cell-Specific Alterations in Alzheimer's Disease and Relevance of In Vitro Models

Alzheimer's disease (AD) is a neurodegenerative disorder classically characterized by two neuropathological hallmarks: β-amyloid plaques and tau tangles in the brain. However, the cellular and molecular mechanisms involved in AD are still elusive, which dampens the possibility of finding new and more effective therapeutic interventions. Current in vitro models are limited in modelling the complexity of AD pathogenesis. In this study, we aimed to characterize the AD expression signature upon a meta-analysis of multiple human datasets, including different cell populations from various brain regions, and compare cell-specific alterations in AD patients and in vitro models to highlight the appropriateness and the limitations of the currently available models in recapitulating AD pathology. The meta-analysis showed consistent enrichment of the Rho GTPases signaling pathway among different cell populations and in the models. The accuracy of in vitro models was higher for neurons and lowest for astrocytes. Our study underscores the particularly low fidelity in modelling down-regulated genes across all cell populations. The top enriched pathways arising from meta-analysis of human data differ from the enriched pathways arising from the overlap. We hope that our data will prove useful in indicating a starting point in the development of future, more complex, 3D in vitro models.

The Inhibition of Mitogen-Activated Protein Kinases (MAPKs) and NF-κB Underlies the Neuroprotective Capacity of a Cinnamon/Curcumin/Turmeric Spice Blend in Aβ-Exposed THP-1 Cells

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by an increased level of β-amyloid (Aβ) protein deposition in the brain, yet the exact etiology remains elusive. Nowadays, treatments only target symptoms, thus the search for novel strategies is constantly stimulated, and looking to natural substances from the plant kingdom. The aim of this study was to investigate the neuroprotective effects of a spice blend composed of cinnamon bark and two different turmeric root extracts (CCSB) in Aβ-exposed THP-1 cells as a model of neuroinflammation. In abiotic assays, CCSB demonstrated an antioxidant capacity up to three times stronger than Trolox in the ORAC assay, and it reduced reactive oxygen species (ROS) induced by the amyloid fragment in THP-1 cells by up to 39.7%. Moreover, CCSB lowered the Aβ stimulated secretion of the pro-inflammatory cytokines IL-1β and IL-6 by up to 24.9% and 43.4%, respectively, along with their gene expression by up to 25.2% and 43.1%, respectively. The mechanism involved the mitogen-activated protein kinases ERK, JNK and p38, whose phosphorylation was reduced by up to 51.5%, 73.7%, and 58.2%, respectively. In addition, phosphorylation of p65, one of the five components forming NF-κB, was reduced by up to 86.1%. Our results suggest that CCSB can counteract the neuroinflammatory stimulus induced by Aβ-exposure in THP-1 cells, and therefore can be considered a potential candidate for AD management.

Targeting protein kinases for the treatment of Alzheimer's disease: Recent progress and future perspectives

Alzheimer's disease (AD) is a serious neurodegenerative disease characterized by memory impairment, mental retardation, impaired motor balance, loss of self-care and even death. Among the complex and diverse pathological changes in AD, protein kinases are deeply involved in abnormal phosphorylation of Tau proteins to form intracellular neuronal fiber tangles, neuronal loss, extracellular β-amyloid (Aβ) deposits to form amyloid plaques, and synaptic disturbances. As a disease of the elderly, the growing geriatric population is directly driving the market demand for AD therapeutics, and protein kinases are potential targets for the future fight against AD. This perspective provides an in-depth look at the role of the major protein kinases (GSK-3β, CDK5, p38 MAPK, ERK1/2, and JNK3) in the pathogenesis of AD. At the same time, the development of different protein kinase inhibitors and the current state of clinical advancement are also outlined.

Role of multi-targeted bioactive natural molecules and their derivatives in the treatment of Alzheimer's disease: an insight into structure-activity relationship

Alzheimer's disease (AD) is a complex neurodegenerative disorder involving cognitive dysfunction like short-term memory and behavioral changes as the disease progresses due to other unaltered physiological factors. The solution for this problem is Multi-targeted Drugs (MTDs), which can affect multiple determinants to realize the multifunctional effects. Acetylcholinesterase (AChE) inhibitors donepezil, rivastigmine, galantamine, and N-methyl-D-aspartate (NMDA) receptor antagonist memantine are FDA-approved drugs used to treat AD symptomatically. The key objective of this review is to understand multitargeted bioactive natural molecules that could be considered as leads for further development as effective drugs for treating AD, along with understanding its pharmacology and structure-activity relationship (SAR). Understanding the molecular mechanism of the AD pathophysiology, the role of existing drugs, treatment of AD via amyloid beta (Aβ) plaque, and neurofibrillary tangle (NFT) inhibition by natural bioactive molecules were also discussed in the review. The current quest and recent advancements with natural bioactive compounds like physostigmine, resveratrol, curcumin, and catechins, along with the study of in silico SAR, were reported in the present study. This review summarises the structural properties required for bioactive natural molecules to show anti-Alzheimer's activity by emphasizing on SAR of several bioactive natural molecules targeting various AD pathologies, their key molecular interactions that are critical for target specificity, their role as multitargeted ligands, used with adjunctive therapy for AD followed by related US patents granted recently. This article highlights the significance of the structural features of natural bioactive molecules in the treatment of AD and establishes a connection between them.Communicated by Ramaswamy H. Sarma.

Use of a gene expression signature to identify trimetazidine for repurposing to treat bipolar depression

OBJECTIVES

The aim of this study was to repurpose a drug for the treatment of bipolar depression.

METHODS

A gene expression signature representing the overall transcriptomic effects of a cocktail of drugs widely prescribed to treat bipolar disorder was generated using human neuronal-like (NT2-N) cells. A compound library of 960 approved, off-patent drugs were then screened to identify those drugs that affect transcription most similar to the effects of the bipolar depression drug cocktail. For mechanistic studies, peripheral blood mononuclear cells were obtained from a healthy subject and reprogrammed into induced pluripotent stem cells, which were then differentiated into co-cultured neurons and astrocytes. Efficacy studies were conducted in two animal models of depressive-like behaviours (Flinders Sensitive Line rats and social isolation with chronic restraint stress rats).

RESULTS

The screen identified trimetazidine as a potential drug for repurposing. Trimetazidine alters metabolic processes to increase ATP production, which is thought to be deficient in bipolar depression. We showed that trimetazidine increased mitochondrial respiration in cultured human neuronal-like cells. Transcriptomic analysis in induced pluripotent stem cell-derived neuron/astrocyte co-cultures suggested additional mechanisms of action via the focal adhesion and MAPK signalling pathways. In two different rodent models of depressive-like behaviours, trimetazidine exhibited antidepressant-like activity with reduced anhedonia and reduced immobility in the forced swim test.

CONCLUSION

Collectively our data support the repurposing of trimetazidine for the treatment of bipolar depression.

Simple model systems reveal conserved mechanisms of Alzheimer's disease and related tauopathies

The lack of effective therapies that slow the progression of Alzheimer's disease (AD) and related tauopathies highlights the need for a more comprehensive understanding of the fundamental cellular mechanisms underlying these diseases. Model organisms, including yeast, worms, and flies, provide simple systems with which to investigate the mechanisms of disease. The evolutionary conservation of cellular pathways regulating proteostasis and stress response in these organisms facilitates the study of genetic factors that contribute to, or protect against, neurodegeneration. Here, we review genetic modifiers of neurodegeneration and related cellular pathways identified in the budding yeast Saccharomyces cerevisiae, the nematode Caenorhabditis elegans, and the fruit fly Drosophila melanogaster, focusing on models of AD and related tauopathies. We further address the potential of simple model systems to better understand the fundamental mechanisms that lead to AD and other neurodegenerative disorders.

Investigating the Potential Anti-Alzheimer's Disease Mechanism of Marine Polyphenols: Insights from Network Pharmacology and Molecular Docking

Marine polyphenols, including eckol(EK), dieckol(DK), and 8,8'-bieckol(BK), have attracted attention as bioactive ingredients for preventing Alzheimer's disease (AD). Since AD is a multifactorial disorder, the present study aims to provide an unbiased elucidation of unexplored targets of AD mechanisms and a systematic prediction of effective preventive combinations of marine polyphenols. Based on the omics data between each compound and AD, a protein-protein interaction (PPI) network was constructed to predict potential hub genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to provide further biological insights. In the PPI network of the top 10 hub genes, AKT1, SRC, EGFR, and ESR1 were common targets of EK and BK, whereas PTGS2 was a common target of DK and BK. GO and KEGG pathway analysis revealed that the overlapped genes between each compound and AD were mainly enriched in EGFR tyrosine kinase inhibitor resistance, the MAPK pathway, and the Rap1 and Ras pathways. Finally, docking validation showed stable binding between marine polyphenols and their top hub gene via the lowest binding energy and multiple interactions. The results expanded potential mechanisms and novel targets for AD, and also provided a system-level insight into the molecular targets of marine polyphenols against AD.

Activation of p38 MAPK hinders the reactivation of visual cortical plasticity in adult amblyopic mice

OBJECTIVE

To investigate the impact of p38 mitogen-activated protein kinase (MAPK) signaling on reactivating visual cortical plasticity in adult amblyopic mice.

MATERIALS AND METHODS

Reverse suture (RS), environment enrichment (EE), and combined with left intracerebroventricular injection of p38 MAPK inhibitor (SB203580, SB) or p38 MAPK agonist (dehydrocorydaline hydrochloride, DHC) were utilized to treat adult amblyopic mice with monocular deprivation (MD). The visual water task, visual cliff test, and Flash visual-evoked potential were used to measure the visual function. Then, Golgi staining and transmission electron microscopy were used to assess the reactivation of structural plasticity in adult amblyopic mice. Western blot and immunohistochemistry detected the expression of ATF2, PSD-95, p38 MAPK, and phospho-p38 MAPK in the left visual cortex.

RESULTS

No statistically significant difference was observed in the visual function in each pre-intervention group. Compared to pre-intervention, the visual acuity of deprived eyes was improved significantly, the impairment of visual depth perception was alleviated, and the P wave amplitude and C/I ratio were increased in the EE + RS, the EE + RS + SB, and the EE + RS + DMSO groups, but no significant difference was detected in the EE + RS + DHC group. Compared to EE + RS + DHC group, the density of dendritic spines was significantly higher, the synaptic density of the left visual cortex increased significantly, the length of the active synaptic zone increased, and the thickness of post-synaptic density (PSD) thickened in the left visual cortex of EE + RS, EE + RS + SB, and EE + RS + DMSO groups. And that, the protein expression of p-p38 MAPK increased while that of PSD-95 and ATF2 decreased significantly in the left visual cortex of the EE + RS + DHC group mice.

CONCLUSION

RS and EE intervention improved the visual function and synaptic plasticity of the visual cortex in adult amblyopic mice. However, activating p38 MAPK hinders the recovery of visual function by upregulating the phosphorylation of p38 MAPK and decreasing the ATF2 protein expression.

The role of periodontitis-associated bacteria in Alzheimer's disease: A narrative review

Alzheimer's disease causes memory loss and dementia in older adults through a neurodegenerative mechanism. Despite the pathophysiological clarification of this cognitive disorder, novel molecular and cellular pathways should be identified to determine its exact mechanism. Alzheimer's disease (AD) is pathologically characterized by senile plaques comprising beta-amyloid and neurofibrillary tangles (NFTs) formed by hyperphosphorylated tau as a microtubule-associated protein with a key role in the pathogenesis of AD. Periodontitis through inflammatory pathways is a risk factor for deteriorating cognitive impairment in AD patients. Poor oral hygiene coupled with immunocompromised status in older adults causes periodontal diseases and chronic inflammations through an oral bacterial imbalance. Toxic bacterial products, including bacteria themselves, can reach the central nervous system through the bloodstream and evoke inflammatory responses. The present review was conducted to investigate relationships between AD and periodontitis-involved bacteria as a risk factor.

The Deficits of Insulin Signal in Alzheimer's Disease and the Mechanisms of Vanadium Compounds in Curing AD

Vanadium is a well-known essential trace element, which usually exists in oxidation states in the form of a vanadate cation intracellularly. The pharmacological study of vanadium began with the discovery of its unexpected inhibitory effect on ATPase. Thereafter, its protective effects on β cells and its ability in glucose metabolism regulation were observed from the vanadium compound, leading to the application of vanadium compounds in clinical trials for curing diabetes. Alzheimer's disease (AD) is the most common dementia disease in elderly people. However, there are still no efficient agents for treating AD safely to date. This is mainly because of the complexity of the pathology, which is characterized by senile plaques composed of the amyloid-beta (Aβ) protein in the parenchyma of the brain and the neurofibrillary tangles (NFTs), which are derived from the hyperphosphorylated tau protein in the neurocyte, along with mitochondrial damage, and eventually the central nervous system (CNS) atrophy. AD was also illustrated as type-3 diabetes because of the observations of insulin deficiency and the high level of glucose in cerebrospinal fluid (CSF), as well as the impaired insulin signaling in the brain. In this review, we summarize the advances in applicating the vanadium compound to AD treatment in experimental research and point out the limitations of the current study using vanadium compounds in AD treatment. We hope this will help future studies in this field.

Therapeutic Strategies Aimed at Improving Neuroplasticity in Alzheimer Disease

Alzheimer disease (AD) is the most prevalent form of dementia among elderly people. Owing to its varied and multicausal etiopathology, intervention strategies have been highly diverse. Despite ongoing advances in the field, efficient therapies to mitigate AD symptoms or delay their progression are still of limited scope. Neuroplasticity, in broad terms the ability of the brain to modify its structure in response to external stimulation or damage, has received growing attention as a possible therapeutic target, since the disruption of plastic mechanisms in the brain appear to correlate with various forms of cognitive impairment present in AD patients. Several pre-clinical and clinical studies have attempted to enhance neuroplasticity via different mechanisms, for example, regulating glucose or lipid metabolism, targeting the activity of neurotransmitter systems, or addressing neuroinflammation. In this review, we first describe several structural and functional aspects of neuroplasticity. We then focus on the current status of pharmacological approaches to AD stemming from clinical trials targeting neuroplastic mechanisms in AD patients. This is followed by an analysis of analogous pharmacological interventions in animal models, according to their mechanisms of action.

Regulatory role of the p38 MAPK/ATF2 signaling pathway in visual function and visual cortical plasticity in mice with monocular deprivation

BACKGROUND

This study aimed to examine the role of the p38 mitogen-activated protein kinase (MAPK)/ activating transcription factor 2 (ATF2) signaling in visual function impairment and visual cortical plasticity in mice with monocular deprivation (MD).

METHODS

Visual behavioral tests, including visual water task, visual cliff test, and flash visual evoked potential, were performed on each group. We studied the density of dendritic spines and the synaptic ultrastructure by Golgi staining and transmission electron microscope. We performed Western blot and immunohistochemistry and detected the expression of ATF2, PSD-95, p38 MAPK, and phosphor-p38 MAPK in the left visual cortex.

RESULTS

In the MD + SB group, the visual acuity in deprived eyes substantially improved, the impairment of visual depth perception was alleviated, and the P wave amplitude and C/I ratio increased. The density of dendritic spines and the numerical density of synapses increased significantly, the width of the synaptic cleft decreased significantly, and the length of the active synaptic zone and the thickness of post-synaptic density (PSD) increased substantially. The protein expression of phosphor-p38 MAPK decreased, whereas that of PSD-95 and ATF2 increased significantly.

CONCLUSIONS

Inhibiting the phosphorylation of p38 MAPK and negative feedback upregulated ATF2 expression, alleviated damage to visual function, and protected against synaptic plasticity in mice with MD.

Alzheimer's disease and neuroinflammation: will new drugs in clinical trials pave the way to a multi-target therapy?

Despite extensive research, no disease-modifying therapeutic option, able to prevent, cure or halt the progression of Alzheimer's disease [AD], is currently available. AD, a devastating neurodegenerative pathology leading to dementia and death, is characterized by two pathological hallmarks, the extracellular deposits of amyloid beta (Aβ) and the intraneuronal deposits of neurofibrillary tangles (NFTs) consisting of altered hyperphosphorylated tau protein. Both have been widely studied and pharmacologically targeted for many years, without significant therapeutic results. In 2022, positive data on two monoclonal antibodies targeting Aβ, donanemab and lecanemab, followed by the 2023 FDA accelerated approval of lecanemab and the publication of the final results of the phase III Clarity AD study, have strengthened the hypothesis of a causal role of Aβ in the pathogenesis of AD. However, the magnitude of the clinical effect elicited by the two drugs is limited, suggesting that additional pathological mechanisms may contribute to the disease. Cumulative studies have shown inflammation as one of the main contributors to the pathogenesis of AD, leading to the recognition of a specific role of neuroinflammation synergic with the Aβ and NFTs cascades. The present review provides an overview of the investigational drugs targeting neuroinflammation that are currently in clinical trials. Moreover, their mechanisms of action, their positioning in the pathological cascade of events that occur in the brain throughout AD disease and their potential benefit/limitation in the therapeutic strategy in AD are discussed and highlighted as well. In addition, the latest patent requests for inflammation-targeting therapeutics to be developed in AD will also be discussed.

Synthesis and Preclinical Positron Emission Tomography Imaging of the p38 MAPK Inhibitor [11C]Talmapimod: Effects of Drug Efflux and Sex Differences

Stress-activated kinases are targets of interest in neurodegenerative disease due to their involvement in inflammatory signaling and synaptic dysfunction. The p38α kinase has shown clinical and preclinical promise as a druggable target in several neurodegenerative conditions. We report the radiosynthesis and evaluation of the first positron emission tomography (PET) radiotracer for imaging MAPK p38α/β through radiolabeling of the inhibitor talmapimod (SCIO-469) with carbon-11. [¹¹C]Talmapimod was reliably synthesized by carbon-11 methylation with non-decay corrected radiochemical yields of 3.1 ± 0.7%, molar activities of 38.9 ± 13 GBq/μmol, and >95% radiochemical purity (n = 20). Preclinical PET imaging in rodents revealed a low baseline brain uptake and retention with standardized uptake values (SUV) of ∼0.2 over 90 min; however, pretreatment with the P-glycoprotein (P-gp) drug efflux transporter inhibitor elacridar enabled [¹¹C]talmapimod to pass the blood-brain barrier (>1.0 SUV) with distinct sex differences in washout kinetics. Blocking studies with a structurally dissimilar p38α/β inhibitor, neflamapimod (VX-745), and displacement imaging studies with talmapimod were attempted in elacridar-pretreated rodents, but neither compound displaced radiotracer uptake in the brain of either sex. Ex vivo radiometabolite analysis revealed substantial differences in the composition of radioactive species present in blood plasma but not in brain homogenates at 40 min post radiotracer injection. Digital autoradiography in fresh-frozen rodent brain tissue confirmed that the radiotracer signal was largely non-displaceable in vitro, where self-blocking and blocking with neflamapimod marginally decreased the total signal by 12.9 ± 8.8% and 2.66 ± 2.1% in C57bl/6 healthy controls and 29.3 ± 2.7% and 26.7 ± 12% in Tg2576 rodent brains, respectively. An MDCK-MDR1 assay suggests that talmapimod is likely to suffer from drug efflux in humans as well as rodents. Future efforts should focus on radiolabeling p38 inhibitors from other structural classes to avoid P-gp efflux and non-displaceable binding.

The Cytokine CX3CL1 and ADAMs/MMPs in Concerted Cross-Talk Influencing Neurodegenerative Diseases

Neuroinflammation plays a fundamental role in the development and progression of neurodegenerative diseases. It could therefore be said that neuroinflammation in neurodegenerative pathologies is not a consequence but a cause of them and could represent a therapeutic target of neuronal degeneration. CX3CL1 and several proteases (ADAMs/MMPs) are strongly involved in the inflammatory pathways of these neurodegenerative pathologies with multiple effects. On the one hand, ADAMs have neuroprotective and anti-apoptotic effects; on the other hand, they target cytokines and chemokines, thus causing inflammatory processes and, consequently, neurodegeneration. CX3CL1 itself is a cytokine substrate for the ADAM, ADAM17, which cleaves and releases it in a soluble isoform (sCX3CL1). CX3CL1, as an adhesion molecule, on the one hand, plays an inhibiting role in the pro-inflammatory response in the central nervous system (CNS) and shows neuroprotective effects by binding its membrane receptor (CX3CR1) present into microglia cells and maintaining them in a quiescent state; on the other hand, the sCX3CL1 isoform seems to promote neurodegeneration. In this review, the dual roles of CX3CL1 and ADAMs/MMPs in different neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (MH), and multiple sclerosis (MS), are investigated.

Neuroprotective potential of biochanin-A and review of the molecular mechanisms involved

Biochanin-A is a naturally occurring plant phytoestrogen, which mimics specific the agonistic activity of estrogens. Biochanin-A is known to possess numerous activities, including neuroprotective, anti-diabetic, hepatoprotective, anti-inflammatory, antioxidant, and antimicrobial activities, along with the anticancer activity. Neuroinflammation is thought to play a pivotal pathological role in neurodegenerative disease. Sustained neuroinflammatory processes lead to progressive neuronal damage in Parkinson's and Alzheimer's disease. Activation of PI3K/Akt cascade and inhibition of MAPK signaling cascade have been observed to be responsible for conferring protection against neuroinflammation in neurodegenerative diseases. An increased oxidative stress promotes neuronal apoptosis via potentiating the TLR-4/NF-κB and inhibiting PI3K/Akt signaling mediated increase in pro-apoptotic and decreases in antiapoptotic proteins. Various authors have explored biochanin-A's neuroprotective effect by using various cell lines and animal models. Biochanin-A has been reported to mediate its neuroprotective via reducing the level of oxidants, inflammatory mediators, MAPK, TLR-4, NF-κB, NADPH oxidase, AchE, COX-2 and iNOS. Whereas, it has been observed to increase the level of anti-oxidants, along with phosphorylation of PI3K and Akt proteins. The current review has been designed to provide insights into the neuroprotective effect of biochanin-A and possible signaling pathways leading to protection against neuroinflammation and apoptosis in the central nervous system. This review will be helpful in guiding future researchers to further explore biochanin A at a mechanistic level to obtain useful lead molecules.

Effect of β-amyloid on blood-brain barrier properties and function

The deposition of beta-amyloid (Aβ) aggregates in the brain, accompanied by impaired cognitive function, is a characteristic feature of Alzheimer's disease (AD). An important role in this process is played by vascular disorders, in particular, a disturbance of the blood-brain barrier (BBB). The BBB controls the entry of Aβ from plasma to the brain via the receptor for advanced glycation end products (RAGE) and the removal of brain-derived Aβ via the low-density lipoprotein receptor-related protein (LRP1). The balance between the input of Aβ to the brain from the periphery and its output is disturbed during AD. Aβ changes the redox-status of BBB cells, which in turn changes the functioning of mitochondria and disrupts the barrier function of endothelial cells by affecting tight junction proteins. Aβ oligomers have the greatest toxic effect on BBB cells, and oligomers are most rapidly transferred by transcytosis from the brain side of the BBB to the blood side. Both the cytotoxic effect of Aβ and the impairment of barrier function are partly due to the interaction of Aβ monomers and oligomers with membrane-bound RAGE. AD therapies based on the disruption of this interaction or the creation of decoys for Aβ are being developed. The question of the transfer of various Aβ isoforms through the BBB is important, since it can influence the development of AD. It is shown that the rate of input of Aβ40 and Aβ42 from the blood into the brain is different. The actual question of the transfer of pathogenic Aβ isoforms with post-translational modifications or mutations through the BBB still remains open.

Magnoflorine improves cognitive deficits and pathology of Alzheimer's disease via inhibiting of JNK signaling pathway

BACKGROUND

Cognitive deficit is the main clinical feature of Alzheimer's disease (AD), and the massive death of neuronal cells is the leading cause of cognitive deficits. So, there is an urgent clinical need to discover effective drugs to protect brain neurons from damage in order to treat AD. Naturally-derived compounds have always been an important source of new drug discovery because of their diverse pharmacological activities, reliable efficacy and low toxicity. Magnoflorine is a quaternary aporphine alkaloid, which naturally exist in some commonly used herbal medicines, and has good anti-inflammatory and antioxidant effects. However, magnoflorine has not been reported in AD.

HYPOTHESIS/PURPOSE

To investigate the therapeutic effect and mechanism of magnoflorine on AD.

METHODS

Neuronal damage was detected by flow cytometry, immunofluorescence and western blotting. Oxidative stress was measured by detection of SOD and MDA, as well as JC-1 and reactive oxygen species (ROS) staining. The APP/PS1 mice were given drugs by intraperitoneal injection (I.P.) every day for one month, and then the new object recognition and Morris water maze were used to detect the cognitive ability of the mice.

RESULTS

We demonstrated that magnoflorine reduced Aβ-induced PC12 cell apoptosis and intracellular ROS generation. Further studies found that magnoflorine significantly improved cognitive deficits and AD-type pathology. Most interestingly, the efficacy of magnoflorine was better than that of the clinical control drug donepezil. Mechanistically, based on RNA-sequencing analysis, we found that magnoflorine significantly inhibited phosphorylated c-Jun N-terminal kinase (JNK) in AD models. This result was further validated using a JNK inhibitor.

CONCLUSION

Our results indicate that magnoflorine improves cognitive deficits and pathology of AD through inhibiting of JNK signaling pathway. Thus, magnoflorine may be a potential therapeutic candidate for AD.

CDK10, CDK11, FOXO1, and FOXO3 Gene Expression in Alzheimer's Disease Encephalic Samples

Alzheimer's disease (AD) is a progressive neuroinflammatory and neurodegenerative disorder that affects different regions of the brain. Its pathophysiology includes the accumulation of β-amyloid protein, formation of neurofibrillary tangles, and inflammatory processes. Genetic factors are involved in the onset of AD, but they are not fully elucidated. Identification of gene expression in encephalic tissues of patients with AD may help elucidate its development. Our objectives were to characterize and compare the gene expression of CDK10, CDK11, FOXO1, and FOXO3 in encephalic tissue samples from AD patients and elderly controls, from the auditory cortex and cerebellum. RT-qPCR was used on samples from 82 individuals (45 with AD and 37 controls). We observed a statistically significant increase in CDK10 (p = 0.029*) and CDK11 (p = 0.048*) gene expression in the AD group compared to the control, which was most evident in the cerebellum. Furthermore, the Spearman test demonstrated the presence of a positive correlation of gene expression both in the auditory cortex in the AD group (r = 0.046/p = 0.004) and control group (r = 0.454/p = 0.005); and in the cerebellum in the AD group (r = 0.654 /p < 0.001). There was no statistically significant difference and correlation in the gene expression of FOXO1 and FOXO3 in the AD group and the control. In conclusion, CDK10 and CDK11 have high expression in AD patients compared to control, and they present a positive correlation of gene expression in the analyzed groups and tissues, which suggests that they play an important role in the pathogenesis of AD.

Abdominal surgery plus sevoflurane exposure induces abnormal emotional changes and cognitive dysfunction in aged rats

BACKGROUND

Cognitive impairment, which includes perioperative psychological distress and cognitive dysfunction, can be determined by preoperative and post-operative neuropsychological tests. Several mechanisms have been proposed regarding the two-way communication between the immune system and the brain after surgery. We aimed to understand the mechanisms underlying perioperative neurocognitive disorders (PND) in elderly rats using an experimental abdominal surgery model.

METHODS

24-month-old SD rats were exposed to the abdominal surgery model (AEL) under 3% anesthesia. On day 15 and day 30 post-surgery, fractional anisotropy (FA) using diffusion kurtosis imaging (DKI) was measured. From day 25 to day 30 post-surgery, behavioral tests, including open field test (OFT), Morris water maze (MWM), novel object recognition (NOR), force swimming test (FST), and elevated plus maze (EPM), were performed. Then, the rats were euthanized to perform pathological analysis and western blot measurement.

RESULTS

The rats exposed to AEL surgical treatment demonstrated significantly decreased time crossing the platform in the MWM, decreased recognition index in the NOR, reduced time in the open arm in the EPM, increased immobility time in the FST, and increased number of crossings in the OFT. Aged rats, after AEL exposure, further demonstrated decreased FA in the mPFC, nucleus accumbens (NAc), and hippocampus, together with reduced MAP2 intensity, attenuation of GAD65, VGlut2, CHAT, and phosphorylated P38MAPK expression, and increased reactive astrocytes and microglia.

CONCLUSIONS

In this study, the aged rats exposed to abdominal surgery demonstrated both emotional changes and cognitive dysfunction, which may be associated with neuronal degeneration and reduced phosphorylated P38MAPK.

Porphyromonas gingivalis-induced periodontitis could contribute to cognitive impairment in Sprague–Dawley rats via the P38 MAPK signaling pathway

Background

Periodontitis is one of the most common oral diseases and has been shown to be a risk factor for systemic diseases. Our aim was to investigate the relationship between periodontitis and cognitive impairment and to explore the role of the P38 MAPK signaling pathway in this process.

Methods

We established a periodontitis model by ligating the first molars of SD rats with silk thread and injecting Porphyromonas gingivalis (P. gingivalis) or P. gingivalis plus the P38 MAPK inhibitor SB203580 at the same time for ten weeks. We assessed alveolar bone resorption and spatial learning and memory using microcomputed tomography and the Morris water maze test, respectively. We used transcriptome sequencing to explore the genetic differences between the groups. The gingival tissue, peripheral blood and hippocampal tissue were assessed for the cytokines TNF-α, IL-1β, IL-6, IL-8 and C reactive protein (CRP) with enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT–PCR). We observed the presence of P. gingivalis in the hippocampus of rats by paraffin-fluorescence in situ hybridization (FISH). We determined the activation of microglia by immunofluorescence. Finally, Western blot analysis was employed to determine the expression of amyloid precursor protein (APP), β-site APP-cleaving enzyme 1 (BACE1) and P38MAPK pathway activation.

Results

We demonstrated that silk ligature-induced periodontitis plus injection of P. gingivalis into subgingival tissue could lead to memory and cognitive impairment. Transcriptome sequencing results suggested that there were neurodegenerative diseases in the P. gingivalis group, and the MWM test showed that periodontitis reduced the spatial learning and memory ability of mild cognitive impairment (MCI) model rats. We found high levels of inflammatory factors (TNF-α, IL-1β, IL-6, and IL-8) and CRP in the gingiva, peripheral blood and hippocampus, and the expression of APP and BACE1 was upregulated, as was the P38 MAPK pathway activation. Activated microglia and the presence of P. gingivalis were also found in the hippocampus. P38 MAPK inhibitors mitigated all of these changes.

Conclusion

Our findings strongly suggest that topical application of P. gingivalis increases the inflammatory burden in the peripheral and central nervous systems (CNS) and that neuroinflammation induced by activation of P38 MAPK leads to impaired learning and memory in SD rats. It can also modulate APP processing. Therefore, P38 MAPK may serve as a linking pathway between periodontitis and cognitive impairment.

Chemical Knockdown of Phosphorylated p38 Mitogen-Activated Protein Kinase (MAPK) as a Novel Approach for the Treatment of Alzheimer's Disease

Targeted protein degradation (TPD) provides unique advantages over gene knockdown in that it can induce selective degradation of disease-associated proteins attributed to pathological mutations or aberrant post-translational modifications (PTMs). Herein, we report a protein degrader, PRZ-18002, that selectively binds to an active form of p38 MAPK. PRZ-18002 induces degradation of phosphorylated p38 MAPK (p-p38) and a phosphomimetic mutant of p38 MAPK in a proteasome-dependent manner. Given that the activation of p38 MAPK plays pivotal roles in the pathophysiology of Alzheimer's disease (AD), selective degradation of p-p38 may provide an attractive therapeutic option for the treatment of AD. In the 5xFAD transgenic mice model of AD, intranasal treatment of PRZ-18002 reduces p-p38 levels and alleviates microglia activation and amyloid beta (Aβ) deposition, leading to subsequent improvement of spatial learning and memory. Collectively, our findings suggest that PRZ-18002 ameliorates AD pathophysiology via selective degradation of p-p38, highlighting a novel therapeutic TPD modality that targets a specific PTM to induce selective degradation of neurodegenerative disease-associated protein.

Dietary Protection against Cognitive Impairment, Neuroinflammation and Oxidative Stress in Alzheimer's Disease Animal Models of Lipopolysaccharide-Induced Inflammation

Alzheimer's disease (AD) is a rapidly growing epidemic with a heavy social and economic burden. Evidence suggests that systemic inflammation, dysregulation of the immune response and the resulting neuroinflammation and neurodegeneration play a significant role in AD pathogenesis. Currently, given that there is no fully convincing cure for AD, the interest in lifestyle factors (such as diet), which potentially delay onset and reduce the severity of symptoms, is increasing. This review is aimed at summarizing the effects of dietary supplementation on cognitive decline, neuroinflammation and oxidative stress in AD-like animal models with a focus on neuroinflammation induced by lipopolysaccharide (LPS) injection, which mimics systemic inflammation in animals. The compounds reviewed include curcumin, krill oil, chicoric acid, plasmalogens, lycopene, tryptophan-related dipeptides, hesperetin and selenium peptides. Despite the heterogeneity of these compounds, there is a strong consensus on their counteracting action on LPS-induced cognitive deficits and neuroinflammatory responses in rodents by modulating cell-signaling processes, such as the NF-κB pathway. Overall, dietary interventions could represent an important resource to oppose AD due to their influence in neuroprotection and immune regulation.

MicroRNAs and MAPKs: Evidence of These Molecular Interactions in Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder known to be the leading cause of dementia worldwide. Many microRNAs (miRNAs) were found deregulated in the brain or blood of AD patients, suggesting a possible key role in different stages of neurodegeneration. In particular, mitogen-activated protein kinases (MAPK) signaling can be impaired by miRNA dysregulation during AD. Indeed, the aberrant MAPK pathway may facilitate the development of amyloid-beta (Aβ) and Tau pathology, oxidative stress, neuroinflammation, and brain cell death. The aim of this review was to describe the molecular interactions between miRNAs and MAPKs during AD pathogenesis by selecting evidence from experimental AD models. Publications ranging from 2010 to 2023 were considered, based on PubMed and Web of Science databases. According to obtained data, several miRNA deregulations may regulate MAPK signaling in different stages of AD and conversely. Moreover, overexpressing or silencing miRNAs involved in MAPK regulation was seen to improve cognitive deficits in AD animal models. In particular, miR-132 is of particular interest due to its neuroprotective functions by inhibiting Aβ and Tau depositions, as well as oxidative stress, through ERK/MAPK1 signaling modulation. However, further investigations are required to confirm and implement these promising results.

Aerial part of Houttuynia cordata reverses memory impairment by regulating amyloid beta accumulation and neuroinflammation in Alzheimer's disease model

Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by amyloid-β (Aβ) deposition, accompanied by neuroinflammation and memory dysfunction. Houttuyniae Herba (aerial parts of Houttuynia cordata, also known as fish mint; HH), an herbal medicine traditionally used to treat fever, urinary disorders, and pus, is revealed to protect neurons from Aβ toxicity and regulate cholinergic dysfunction in AD models. In this study, we aimed to investigate the effects of HH on excessive accumulation of Aβ followed by neuroinflammation, synaptic degeneration, and memory impairment. Two-month-old 5xFAD transgenic mice were administered HH at 100 mg/kg for 4 months. We observed that HH treatment ameliorated memory impairment and reduced Aβ deposits in the brains of the mice. HH directly inhibited Aβ aggregation in vitro using the Thioflavin T assay and indirectly suppressed the amyloidogenic pathway by increasing alpha-secretase expression in the mice brain. In addition, HH exerted antineuroinflammatory effects by reducing of glial activation and p38 phosphorylation. Moreover, HH treatment increased the expression of synaptophysin, a presynaptic marker protein. Overall, HH alleviates memory impairment in AD by facilitating nonamyloidogenic pathway and inhibiting neuroinflammation. Therefore, we suggest that HH can be a promising herbal drug for patients with AD requiring multifaceted improvement.

Drosophila Toll-9 is induced by aging and neurodegeneration to modulate stress signaling and its deficiency exacerbates tau-mediated neurodegeneration

Drosophila Toll-9 is most closely related to mammalian Toll-like receptors; however, physiological functions of Toll-9 remain elusive. We examined the roles of Toll-9 in fly brains in aging and neurodegeneration. Toll-9 mRNA levels were increased in aged fly heads accompanied by activation of nuclear factor-kappa B (NF-kB) and stress-activated protein kinase (SAPK) signaling, and many of these changes were modulated by Toll-9 in glial cells. The loss of Toll-9 did not affect lifespan or brain integrity, whereas it exacerbated hydrogen peroxide-induced lethality. Toll-9 expression was also induced by nerve injury but did not affect acute stress response or glial engulfment activity, suggesting Toll-9 may modulate subsequent neurodegeneration. In a fly tauopathy model, Toll-9 deficiency enhanced neurodegeneration and disease-related tau phosphorylation with reduced SAPK activity, and blocking SAPK enhanced tau phosphorylation and neurodegeneration. In sum, Toll-9 is induced upon aging and nerve injury and affects neurodegeneration by modulating stress kinase signaling.

MicroRNA-125a-3p Modulate Amyloid β-Protein through the MAPK Pathway in Alzheimer's Disease

BACKGROUND

MicroRNA (miR)-125a-3p is reported to play an important role in some central nervous system diseases, such as Alzheimer's disease (AD). However, a study has not been conducted on the mechanism of miR-125a-3p in the pathological process of AD.

METHODS

First, we assessed the expression of miR-125a-3p in AD cohort. Subsequently, we altered the expressions of miR-125a-3p to assess its role in cell viability, cell apoptosis, amyloid-β (Aβ) metabolism, and synaptic activity. Finally, we identified its potential mechanism underlying AD pathology.

RESULTS

This study unveiled the potential function of miR-125a-3p through modulating amyloid precursor protein processing. Additionally, miR-125a-3p influenced cell survival and activated synaptic expression through the modulation of Aβ metabolism in the mitogen-activated protein kinase (MAPK) pathway via fibroblast growth factor receptor 2.

CONCLUSION

Our study indicates that targeting miR-125a-3p may be an applicable therapy for AD in the future. However, more in vitro and in vivo studies with more samples are needed to confirm these results.

RAGE and its ligand amyloid beta promote retinal ganglion cell loss following ischemia-reperfusion injury

Introduction

Glaucoma is a progressive neurodegenerative disease associated with age. Accumulation of amyloid-beta (Aß) proteins in the ganglion cell layer (GCL) and subsequent retinal ganglion cell (RGC) loss is an established pathological hallmark of the disease. The mechanism through which Aß provokes RGC loss remains unclear. The receptor for the advanced glycation end product (RAGE), and its ligand Aß, have been shown to mediate neuronal loss via internalizing Aß within the neurons. In this study, we investigated whether the RAGE-Aß axis plays a role in RGC loss in experimental glaucoma.

Methods

Retinal ischemia was induced by an acute elevation of intraocular pressure in RAGE^-/- and wild-type (WT) control mice. In a subset of animals, oligomeric Aß was injected directly into the vitreous of both strains. RGC loss was assessed using histology and biochemical assays. Baseline and terminal positive scotopic threshold (pSTR) were also recorded.

Results

Retinal ischemia resulted in 1.9-fold higher RGC loss in WT mice compared to RAGE^-/- mice (36 ± 3% p < 0.0001 vs. 19 ± 2%, p = 0.004). Intravitreal injection of oligomeric Aß resulted in 2.3-fold greater RGC loss in WT mice compared to RAGE^-/- mice, 7-days post-injection (55 ± 4% p = 0.008 vs. 24 ± 2%, p = 0.02). We also found a significant decline in the positive scotopic threshold response (pSTR) amplitude of WT mice compared to RAGE^-/- (36 ± 3% vs. 16 ± 6%).

Discussion

RAGE^-/- mice are protected against RGC loss following retinal ischemia. Intravitreal injection of oligomeric Aß accelerated RGC loss in WT mice but not RAGE^-/-. A co-localization of RAGE and Aß, suggests that RAGE-Aß binding may contribute to RGC loss.

Amyloid-beta aggregation implicates multiple pathways in Alzheimer's disease: Understanding the mechanisms

Alzheimer's disease (AD) is a progressive neurodegenerative condition characterized by tau pathology and accumulations of neurofibrillary tangles (NFTs) along with amyloid-beta (Aβ). It has been associated with neuronal damage, synaptic dysfunction, and cognitive deficits. The current review explained the molecular mechanisms behind the implications of Aβ aggregation in AD via multiple events. Beta (β) and gamma (γ) secretases hydrolyzed amyloid precursor protein (APP) to produce Aβ, which then clumps together to form Aβ fibrils. The fibrils increase oxidative stress, inflammatory cascade, and caspase activation to cause hyperphosphorylation of tau protein into neurofibrillary tangles (NFTs), which ultimately lead to neuronal damage. Acetylcholine (Ach) degradation is accelerated by upstream regulation of the acetylcholinesterase (AChE) enzyme, which leads to a deficiency in neurotransmitters and cognitive impairment. There are presently no efficient or disease-modifying medications for AD. It is necessary to advance AD research to suggest novel compounds for treatment and prevention. Prospectively, it might be reasonable to conduct clinical trials with unclean medicines that have a range of effects, including anti-amyloid and anti-tau, neurotransmitter modulation, anti-neuroinflammatory, neuroprotective, and cognitive enhancement.