Oxidative Stress and Natural Antioxidants: Back and Forth in the Neurological Mechanisms of Alzheimer's Disease

Unveiling the Involvement of Herpes Simplex Virus-1 in Alzheimer's Disease: Possible Mechanisms and Therapeutic Implications

Viruses pose a significant challenge and threat to human health, as demonstrated by the current COVID-19 pandemic. Neurodegeneration, particularly in the case of Alzheimer's disease (AD), is significantly influenced by viral infections. AD is a neurodegenerative disease that affects people of all ages and poses a significant threat to millions of individuals worldwide. The precise mechanism behind its development is not yet fully understood; however, the emergence and advancement of AD can be hastened by various environmental factors, such as bacterial and viral infections. There has been a longstanding suspicion that the herpes simplex virus-1 (HSV-1) may have a role to play in the development or advancement of AD. Reactivation of HSV-1 could potentially lead to damage to neurons, either by direct means or indirectly by triggering inflammation. This article provides an overview of the connection between HSV-1 infections and immune cells (astrocytes, microglia, and oligodendrocytes) in the progression of AD. It summarizes recent scientific research on how HSV-1 affects neurons, which could potentially shed light on the clinical features and treatment options for AD. In addition, the paper has explored the impact of HSV-1 on neurons and its role in various aspects of AD, such as Aβ secretion, tau hyperphosphorylation, metabolic dysregulation, oxidative damage, apoptosis, and autophagy. It is believed that the immune response triggered by HSV-1 reactivation plays a role in the development of neurodegeneration in AD. Despite the lack of a cure for AD, researchers have made significant efforts to study the clinical and pathological aspects of the disease, identify biomarkers, and gain insight into its underlying causes. The goal is to achieve early diagnosis and develop treatments that can modify the progression of the disease. The current article discusses the most promising therapy for combating the viral impacts, which provides additional evidence for the frequent reactivations of latent HSV-1 in the AD brain. However, further research is still required to establish the molecular and cellular mechanisms underlying the development of AD through the reactivation of HSV-1. This could potentially lead to new insights in drug development aimed at preventing HSV-1 reactivation and the subsequent development and progression of AD.

Potential Roles of Natural Antioxidants in Modulating Neurodegenerative Disease Pathways

Neurodegenerative diseases, including Alzheimer's, Parkinson's, and amyotrophic lateral sclerosis, are increasingly prevalent among aging populations. Oxidative stress contributes to these diseases, leading to cellular damage and neuronal death. Natural antioxidants are being explored as preventive measures. This study aims to assess the effectiveness of natural antioxidants in delaying the onset or progression of neurodegenerative diseases by identifying their specific mechanisms of action. A comprehensive review of existing literature was conducted, focusing on studies that examine the role of natural antioxidants in neuroprotection. Key natural antioxidants, including flavonoids, polyphenls, vitamins C and E, and omega-3 fatty acids, were reviewed and analyzed for their bioavailability, mechanisms of action, and outcomes in both in vitro and in vivo studies. Additionally, clinical trials involving human subjects were considered to provide insights into the translational implications of antioxidant consumption. The findings suggest that several natural antioxidants exhibit neuroprotective properties by modulating oxidative stress, reducing inflammation, and promoting neuronal survival. For instance, flavonoids such as quercetin and resveratrol have shown promise in enhancing cognitive function and mitigating the pathophysiological alterations associated with neurodegeneration. In clinical studies, higher intakes of dietary antioxidants were correlated with a reduced risk of developing neurodegenerative disorders. Natural antioxidants offer potential for preventing neurodegenerative diseases by counteracting oxidative stress and maintaining cellular integrity. Overall, our report recommends that further research is needed to optimize dosages and understand their long-term benefits.

Bibliometric analysis and visualization of lipid droplets in the central nervous system: research hotspots and Frontiers (2000-2024)

Objective

The aim of this study is to conduct bibliometric analysis and visualization of the research progress of lipid droplets in the central nervous system in detail using CiteSpace, VOSviewer, and to explore the current research status, hotspots, and research trends, with a view to providing a basis for future research.

Methods

This study utilized the Web of Science database to search for 1,066 relevant publications on lipid droplets in the central nervous system from 2000 to 2024. Bibliometric analysis was conducted using CiteSpace and VOSviewer software, producing metrics such as annual publication trends, contributions by countries, institutions, and authors, keyword co-occurrences, and reference co-citation networks. The literature of 25 years or so was explored visually to identify the important areas of lipid droplets in neurological research.

Results

Miguel Lopez is the largest contributor to the relevant literature with 10 publications. The United States, China, Johns Hopkins University, the University of Cambridge, and Zhejiang University are the top contributors in terms of publication volume in this research area. Current research emphasizes the mechanisms of lipid droplets in oxidative stress, neuroinflammation, and related degenerative diseases, with a particular focus on Alzheimer's Disease.

Conclusion

Our analysis suggests enhancing collaboration among countries, institutions, and authors in clinical and basic research on brain lipid droplets.

From Genetics to Neuroinflammation: The Impact of ApoE4 on Microglial Function in Alzheimer's Disease

Alzheimer's disease (AD) is a debilitating neurodegenerative disorder marked by progressive cognitive decline and memory loss, impacting millions of people around the world. The apolipoprotein E4 (ApoE4) allele is the most prominent genetic risk factor for late-onset AD, dramatically increasing disease susceptibility and accelerating onset compared to its isoforms ApoE2 and ApoE3. ApoE4's unique structure, which arises from single-amino-acid changes, profoundly alters its function. This review examines the critical interplay between ApoE4 and microglia-the brain's resident immune cells-and how this relationship contributes to AD pathology. We explore the molecular mechanisms by which ApoE4 modulates microglial activity, promoting a pro-inflammatory state, impairing phagocytic function, and disrupting lipid metabolism. These changes diminish microglia's ability to clear amyloid-beta peptides, exacerbating neuroinflammation and leading to neuronal damage and synaptic dysfunction. Additionally, ApoE4 adversely affects other glial cells, such as astrocytes and oligodendrocytes, further compromising neuronal support and myelination. Understanding the ApoE4-microglia axis provides valuable insights into AD progression and reveals potential therapeutic targets. We discuss current strategies to modulate ApoE4 function using small molecules, antisense oligonucleotides, and gene editing technologies. Immunotherapies targeting amyloid-beta and ApoE4, along with neuroprotective approaches to enhance neuronal survival, are also examined. Future directions highlight the importance of personalized medicine based on individual ApoE genotypes, early biomarker identification for risk assessment, and investigating ApoE4's role in other neurodegenerative diseases. This review emphasizes the intricate connection between ApoE4 and microglial dysfunction, highlighting the necessity of targeting this pathway to develop effective interventions. Advancing our understanding in this area holds promise for mitigating AD progression and improving outcomes for those affected by this relentless disease.

Microglial polarization in Alzheimer's disease: Mechanisms, implications, and therapeutic opportunities

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of amyloid-β plaques, neurofibrillary tangles, and chronic neuroinflammation. Microglial cells, the resident immune cells in the central nervous system, play a crucial role in the pathogenesis of AD. Microglia can undergo polarization, shifting between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes in response to different stimuli. Dysregulation of microglial polarization towards the pro-inflammatory phenotype leads to the release of inflammatory cytokines, oxidative stress, and synaptic dysfunction. These processes contribute to neuronal damage and cognitive decline in AD. However, several challenges remain in this field. The complex molecular mechanisms governing microglial polarization in AD need to be further elucidated. In this review, we discuss the mechanisms underlying microglial polarization in AD and its implications in disease progression.

Advances in Pharmacological Research on Icaritin: A Comprehensive Review

Epimedium has been widely used in traditional Chinese medicine for several thousands of years. This plant is known for tonifying kidney Yang, strengthening muscles and bones, and dispelling wind and dampness. It is worth noting that icaritin, a prenylated flavonoid isolated from Epimedium, has received increasing attention in recent years due to its wide range of pharmacological activities. Icaritin exhibits significant therapeutic potential against various diseases, such as osteoporosis, tumors (hepatocellular carcinoma, stomach cancer, breast cancer, and glioblastoma), cerebral ischemia skin injury, thrombocytopenia, and systemic lupus erythematosus. We review the pharmacological activities of icaritin and its potential molecular mechanisms for the treatment of related diseases. The data suggest that icaritin can have the pharmacological effects of mediating Wnt/[Formula: see text]-catenin, IL-6/JAK2/STAT3, AMPK/mTOR, PTEN/AKT, MAPK, NF-[Formula: see text]B, and other signaling pathways. This paper also discusses the progress of clinical trials of icaritin. Icaritin was approved by the State Food and Drug Administration in January 2022 for the treatment of advanced HCC, and has various clinical drug prospects. Although it has some disadvantages, including poor solubility, and low bioavailability, icaritin is still a prospective candidate for the development of naturally derived drugs, especially in the treatment of tumors and inflammatory diseases. This review aims to update and deepen the understanding of icaritin, and provide a theoretical basis for its further study.

Current Progress on Postoperative Cognitive Dysfunction: An Update

Postoperative cognitive dysfunction (POCD) represents a significant clinical concern, particularly among elderly surgical patients. It is characterized by a decline in cognitive performance, affecting memory, attention, coordination, orientation, verbal fluency, and executive function. This decline in cognitive abilities leads to longer hospital stays and increased mortality. This review provides a comprehensive overview of the current progress in understanding the relevant pathogenic factors, possible pathogenic mechanisms, diagnosing, prevention and treatment of POCD, as well as suggesting future research directions. It discusses neuronal damage, susceptible genes, central cholinergic system, central nervous system (CNS) inflammation, stress response and glucocorticoids, and oxidative stress in the development of POCD, aiming to uncover the pathological mechanism and develop effective treatment strategies for POCD.

Investigating the Potential Therapeutic Mechanisms of Puerarin in Neurological Diseases

Plants and their derived phytochemicals have a long history of treating a wide range of illnesses for several decades. They are believed to be the origin of a diverse array of medicinal compounds. One of the compounds found in kudzu root is puerarin, a isoflavone glycoside commonly used as an alternative medicine to treat various diseases. From a biological perspective, puerarin can be described as a white needle crystal with the chemical name of 7-hydroxy-3-(4-hydroxyphenyl)-1-benzopyran-4-one-8-D-glucopyranoside. Besides, puerarin is sparingly soluble in water and produces no color or light yellow solution. Multiple experimental and clinical studies have confirmed the significant therapeutic effects of puerarin. These effects span a wide range of pharmacological effects, including neuroprotection, hepatoprotection, cardioprotection, immunomodulation, anticancer properties, anti-diabetic properties, anti-osteoporosis properties, and more. Puerarin achieves these effects by interacting with various cellular and molecular pathways, such as MAPK, AMPK, NF-κB, mTOR, β-catenin, and PKB/Akt, as well as different receptors, enzymes, and growth factors. The current review highlights the molecular mechanism of puerarin as a neuroprotective agent in the treatment of various neurodegenerative and neurological diseases. Extensive cellular, animal, and clinical research has provided valuable insights into its effectiveness in conditions such as Alzheimer's disease, Parkinson's disease, epilepsy, cerebral stroke, depression, and more.

Alzheimer's Disease, Obesity, and Type 2 Diabetes: Focus on Common Neuroglial Dysfunctions (Critical Review and New Data on Human Brain and Models)

BACKGROUND/OBJECTIVES

Obesity, type 2 diabetes (T2D), and Alzheimer's disease (AD) are pathologies that affect millions of people worldwide. They have no effective therapy and are difficult to prevent and control when they develop. It has been known for many years that these diseases have many pathogenic aspects in common. We highlight in this review that neuroglial cells (astroglia, oligodendroglia, and microglia) play a vital role in the origin, clinical-pathological development, and course of brain neurodegeneration. Moreover, we include the new results of a T2D-AD mouse model (APP+PS1 mice on a high-calorie diet) that we are investigating.

METHODS

Critical bibliographic revision and biochemical neuropathological study of neuroglia in a T2D-AD model.

RESULTS

T2D and AD are not only "connected" by producing complex pathologies in the same individual (obesity, T2D, and AD), but they also have many common pathogenic mechanisms. These include insulin resistance, hyperinsulinemia, hyperglycemia, oxidative stress, mitochondrial dysfunction, and inflammation (both peripheral and central-or neuroinflammation). Cognitive impairment and AD are the maximum exponents of brain neurodegeneration in these pathological processes. both due to the dysfunctions induced by metabolic changes in peripheral tissues and inadequate neurotoxic responses to changes in the brain. In this review, we first analyze the common pathogenic mechanisms of obesity, T2D, and AD (and/or cerebral vascular dementia) that induce transcendental changes and responses in neuroglia. The relationships between T2D and AD discussed mainly focus on neuroglial responses. Next, we present neuroglial changes within their neuropathological context in diverse scenarios: (a) aging involution and neurodegenerative disorders, (b) human obesity and diabetes and obesity/diabetes models, (c) human AD and in AD models, and (d) human AD-T2D and AD-T2D models. An important part of the data presented comes from our own studies on humans and experimental models over the past few years. In the T2D-AD section, we included the results of a T2D-AD mouse model (APP+PS1 mice on a high-calorie diet) that we investigated, which showed that neuroglial dysfunctions (astrocytosis and microgliosis) manifest before the appearance of amyloid neuropathology, and that the amyloid pathology is greater than that presented by mice fed a normal, non-high-caloric diet A broad review is finally included on pharmacological, cellular, genic, and non-pharmacological (especially diet and lifestyle) neuroglial-related treatments, as well as clinical trials in a comparative way between T2D and AD. These neuroglial treatments need to be included in the multimodal/integral treatments of T2D and AD to achieve greater therapeutic efficacy in many millions of patients.

CONCLUSIONS

Neuroglial alterations (especially in astroglia and microglia, cornerstones of neuroinflammation) are markedly defining brain neurodegeneration in T2D and A, although there are some not significant differences between each of the studied pathologies. Neuroglial therapies are a very important and p. promising tool that are being developed to prevent and/or treat brain dysfunction in T2D-AD. The need for further research in two very different directions is evident: (a) characterization of the phenotypic changes of astrocytes and microglial cells in each region of the brain and in each phase of development of each isolated and associated pathology (single-cell studies are mandatory) to better understand the pathologies and define new therapeutic targets; (b) studying new therapeutic avenues to normalize the function of neuroglial cells (preventing neurotoxic responses and/or reversing them) in these pathologies, as well as the phenotypic characteristics in each moment of the course and place of the neurodegenerative process.

From Brain to Muscle: The Role of Muscle Tissue in Neurodegenerative Disorders

Neurodegenerative diseases (NDs), like amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and Parkinson's disease (PD), primarily affect the central nervous system, leading to progressive neuronal loss and motor and cognitive dysfunction. However, recent studies have revealed that muscle tissue also plays a significant role in these diseases. ALS is characterized by severe muscle wasting as a result of motor neuron degeneration, as well as alterations in gene expression, protein aggregation, and oxidative stress. Muscle atrophy and mitochondrial dysfunction are also observed in AD, which may exacerbate cognitive decline due to systemic metabolic dysregulation. PD patients exhibit muscle fiber atrophy, altered muscle composition, and α-synuclein aggregation within muscle cells, contributing to motor symptoms and disease progression. Systemic inflammation and impaired protein degradation pathways are common among these disorders, highlighting muscle tissue as a key player in disease progression. Understanding these muscle-related changes offers potential therapeutic avenues, such as targeting mitochondrial function, reducing inflammation, and promoting muscle regeneration with exercise and pharmacological interventions. This review emphasizes the importance of considering an integrative approach to neurodegenerative disease research, considering both central and peripheral pathological mechanisms, in order to develop more effective treatments and improve patient outcomes.

Phytotherapy in Alzheimer's Disease-A Narrative Review

Alzheimer's disease (AD) affects 50-70% of patients with dementia, making it the leading cause of dementia. The condition is classified as a neurodegenerative, progressive and incurable disease. The disease is affecting more and more people around the world. AD has a multifactorial nature, spreading from beta-amyloid deposition to inflammation in patients' brains. Patients experience cognitive impairment and functional decline. Although it is a disease that occurs mainly in the elderly, it is increasingly being diagnosed in young people between the ages of 30 and 40. It not only affects the patient themself but also reduces the quality of life of their closest caregivers. According to the WHO, the treatment of AD consumes USD 1.3 trillion globally, but it is only symptomatic, as there are no drugs to prevent the onset of AD or treat the cause of its onset. Due to the numerous side effects of therapy and the lack of proactive drugs that act on the pathomechanism of AD, alternative therapies are being sought. One possible option that has many studies confirming its effect is phytotherapy. Many herbs have pharmacological properties, such as antioxidant, anti-inflammatory, or neuroprotective effects, making them the future of cognitive disorders and AD treatment. This review focuses on some of the most promising herbs that have potentially potent properties and effects in AD therapy. These include Curcuma longa, Panax ginseng, Berberis and Crocus sativus. These herbs may perhaps be key in the future to make functioning and life easier for patients struggling with AD.

Biomaterial strategies for regulating the neuroinflammatory response

Injury and disease in the central nervous system (CNS) can result in a dysregulated inflammatory environment that inhibits the repair of functional tissue. Biomaterials present a promising approach to tackle this complex inhibitory environment and modulate the mechanisms involved in neuroinflammation to halt the progression of secondary injury and promote the repair of functional tissue. In this review, we will cover recent advances in biomaterial strategies, including nanoparticles, hydrogels, implantable scaffolds, and neural probe coatings, that have been used to modulate the innate immune response to injury and disease within the CNS. The stages of inflammation following CNS injury and the main inflammatory contributors involved in common neurodegenerative diseases will be discussed, as understanding the inflammatory response to injury and disease is critical for identifying therapeutic targets and designing effective biomaterial-based treatment strategies. Biomaterials and novel composites will then be discussed with an emphasis on strategies that deliver immunomodulatory agents or utilize cell-material interactions to modulate inflammation and promote functional tissue repair. We will explore the application of these biomaterial-based strategies in the context of nanoparticle- and hydrogel-mediated delivery of small molecule drugs and therapeutic proteins to inflamed nervous tissue, implantation of hydrogels and scaffolds to modulate immune cell behavior and guide axon elongation, and neural probe coatings to mitigate glial scarring and enhance signaling at the tissue-device interface. Finally, we will present a future outlook on the growing role of biomaterial-based strategies for immunomodulation in regenerative medicine and neuroengineering applications in the CNS.

Mechanistic insights into the potential role of dietary polyphenols and their nanoformulation in the management of Alzheimer's disease

Alzheimer's disease (AD) is a very common neurodegenerative disorder associated with memory loss and a progressive decline in cognitive activity. The two major pathophysiological factors responsible for AD are amyloid plaques (comprising amyloid-beta aggregates) and neurofibrillary tangles (consisting of hyperphosphorylated tau protein). Polyphenols, a class of naturally occurring compounds, are immensely beneficial for the treatment or management of various disorders and illnesses. Naturally occurring sources of polyphenols include plants and plant-based foods, such as fruits, herbs, tea, vegetables, coffee, red wine, and dark chocolate. Polyphenols have unique properties, such as being the major source of anti-oxidants and possessing anti-aging and anti-cancerous properties. Currently, dietary polyphenols have become a potential therapeutic approach for the management of AD, depending on various research findings. Dietary polyphenols can be an effective strategy to tackle multifactorial events that occur with AD. For instance, naturally occurring polyphenols have been reported to exhibit neuroprotection by modulating the Aβ biogenesis pathway in AD. Many nanoformulations have been established to enhance the bioavailability of polyphenols, with nanonization being the most promising. This review comprehensively provides mechanistic insights into the neuroprotective potential of dietary polyphenols in treating AD. It also reviews the usability of dietary polyphenol as nanoformulation for AD treatment.

Overview of alkyl quercetin lipophenol synthesis and its protective effect against carbonyl stress involved in neurodegeneration

Oxidative stress and carbonyl stress resulting from the toxicity of small aldehydes are part of the detrimental mechanisms leading to neuronal cell loss involved in the progression of neurodegenerative diseases such as Alzheimer's disease. Polyunsaturated alkylated lipophenols represent a new class of hybrid molecules that combine the health benefits of anti-inflammatory omega-3 fatty acids with the anti-carbonyl and oxidative stress (anti-COS) properties of (poly)phenols in a single pharmacological entity. To investigate the therapeutic potential of quercetin-3-docosahexaenoic acid-7-isopropyl lipophenol in neurodegenerative diseases, three synthetic pathways using chemical or chemo-enzymatic strategies were developed to access milligram or gram scale quantities of this alkyl lipophenol. The protective effect of quercetin-3-DHA-7-iPr against cytotoxic concentrations of acrolein (a carbonyl stressor) was assessed in human SHSY-5Y neuroblastoma cells to underscore its ability to alleviate harmful mechanisms associated with carbonyl stress in the context of neurodegenerative diseases.