Impact of Cytokines and Chemokines on Alzheimer's Disease Neuropathological Hallmarks

Blockage of CCL3 with neutralizing antibody reduces neuroinflammation and reverses Alzheimer disease phenotypes

BACKGROUND

Accumulating evidence indicates that neuroinflammation is involved in the pathogenesis of Alzheimer's disease (AD). According to RNA sequencing and quantitative PCR (qPCR), we found that chemokine CCL3 mRNA expression was abnormally upregulated in the brains of AD transgenic mice. Moreover, the levels of CCL3 in the serum of AD patients were significantly elevated and negatively correlated with their cognitive abilities. However, the role of CCL3 in AD neuroinflammation and pathological damages remains elusive.

METHODS

Using behavioral, histological, and biochemical methods, outcomes of CCL3 antibody treatment on neuropathology and cognitive deficits were studied in the APPswe/PS1dE9 mice.

RESULTS

In the present study, we reported that CCL3 protein expression was increased in the APPswe/PS1dE9 mice, whereas blockage of CCL3 with neutralizing antibody potently inhibited CCL3 activation in the APPswe/PS1dE9 mice down to the levels of wild-type mice. Specifically, CCL3 antibody significantly improved the learning and memory abilities of APPswe/PS1dE9 mice. In addition, CCL3 antibody treatment decreased cerebral amyloid-β (Aβ) levels and plaque burden via inhibiting amyloid precursor protein (APP) processing by reducing beta-site APP cleaving enzyme 1 (BACE1) expression in the APPswe/PS1dE9 mice. We also found that CCL3 antibody treatment alleviated neuroinflammation and reduced synaptic defects in the APPswe/PS1dE9 mice. Furthermore, the activated NF-κB signaling pathway in APPswe/PS1dE9 mice was inhibited by CCL3 antibody treatment.

CONCLUSIONS

Collectively, our findings provide evidence that CCL3 activation may contribute to the AD pathogenesis and may serve as a novel therapeutic target in the treatment of AD.

IL-17 A Exacerbated Neuroinflammatory and Neurodegenerative Biomarkers in Intranasal Amyloid-Beta Model of Alzheimer's Disease

Proinflammatory cytokines, especially interleukin-17 A (IL-17 A) have been found to be significantly associated with AD patients. IL-17 A amplifies neuroinflammation during AD pathology. This study highlighted the ability of IL-17 A to exacerbate amyloid-beta-induced pathology in animals. The AD pathology was induced with repeated intranasal administration of Aβ along with recombinant mouse IL-17 A (rmIL-17) at 1, 2 and 4 µg/kg for seven alternate days. Although, the combination of rmIL-17 and Aβ did not have severe effects on memory of the animals, but it drastically increased the IL-17 A mediated signaling, level of proinflammatory cytokines, oxidative stress and reduced antioxidants in the hippocampus and cortex regions of the animal brains. Interestingly, combining rmIL-17 with Aβ also triggered the expression of AD structural markers like pTau, amyloid-beta and BACE1 in the brain regions. Furthermore, rmIL-17 with Aβ exposure stimulated astrocytes and microglia leading to activation of proinflammatory signaling in the brain of the animals. These results showed the propensity of IL-17 A to promote severity of AD pathology and suggest IL-17 A as potent therapeutic target to control AD progression.

Neuroprotective and plasticity promoting effects of repetitive transcranial magnetic stimulation (rTMS): A role for microglia

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used to modulate neocortical excitability, with expanding applications in neurological and psychiatric disorders. However, the cellular and molecular mechanisms underlying its effects, particularly the role of microglia -the resident immune cells of the central nervous system- remain poorly understood. This review synthesizes recent findings on how different rTMS protocols influence microglial function under physiological conditions and in disease models. Emerging evidence indicates that rTMS modulates microglial activation, promoting neuroprotective and plasticity-enhancing processes not only in models of brain disorders, such as Alzheimer's and Parkinson's disease, but also in healthy neural circuits. While much of the current research has focused on the inflammatory profile of microglia, critical aspects such as activity-dependent synaptic remodeling, phagocytic activity, and process motility remain underexplored. Given the substantial heterogeneity of microglial responses across brain regions, age, and sex, as well as their differential roles in health and disease, a deeper understanding of their involvement in rTMS-induced plasticity is essential. Future studies should integrate selective microglial manipulation and advanced structural, functional, and molecular profiling techniques to clarify their causal involvement. Addressing these gaps will be pivotal in optimizing rTMS protocols and maximizing its therapeutic potential across a spectrum of neurological and neuropsychiatric conditions.

Mathematical models on Alzheimer's disease and its treatment: A review

Alzheimer's disease is a gradually advancing neurodegenerative disease. According to the report by "World Health Organization (WHO)", there are over 55 million individuals currently living with Alzheimer's disease and other dementia globally, and the number of sufferers is increasing every day. In absence of effective cures and preventive measures, this number is predicted to triple by 2050. The disease's origin is still unclear, and also no such treatment is available for eradicating the disease. Based on the crucial factors that are connected to the disease's progression, the authors developed several types of mathematical models. We review such mathematical models that are utilized to better understand the pathophysiology of Alzheimer's disease. Section-wise, we categorize the mathematical models in terms of different components that might be responsible for Alzheimer's disease. We explain the mathematical models with their descriptions and respective conclusions. In addition to mathematical models, we concentrate on biological aspects of the disease and possible therapeutic targets. We explore the disease's biological basis primarily to understand how proteins, glial cells, cytokines, genes, calcium signaling and oxidative stress contribute to the disease. We go through several treatment targets that might stop the progression of the disease or at least slow it down. We present a table that summarizes the mathematical models in terms of their formalisms, highlighting key components and important remarks.

Brain interleukins and Alzheimer's disease

The central nervous system (CNS) is immune-privileged by several immuno-modulators as interleukins (ILs). ILs are cytokines secreted by immune cells for cell-cell signaling communications and affect the functions of the CNS. ILs were reported to orchestrate different molecular and cellular mechanisms of both physiological and pathological events, through overproduction or over-expression of their receptors. They interact with numerous receptors mediating pro-inflammatory and/or anti-inflammatory actions. Interleukins have been implicated to participate in neurodegenerative diseases. They play a critical role in Alzheimer's disease (AD) pathology which is characterized by the over-production of pro-inflammatory ILs. These may aggravate neurodegeneration, in addition to their contribution to detrimental mechanisms as oxidative stress, and excitotoxicity. However, recent research on the relation between ILs and AD revealed major discrepancies. Most of the major ILs were shown to play both pro- and anti-inflammatory roles in different experimental settings and models. The interactions between different ILs through shared pathways also add to the difficulty of drawing solid conclusions. In addition, targeting the different ILs has not yielded consistent results. The repeated failures of therapeutic drugs in treating AD necessitate the search for novel agents targeting multiple mechanisms of the disease pathology. In this context, the understanding of interleukins and their roles throughout the disease progression and interaction with other systems in the brain may provide promising therapeutic targets for the prevention or treatment of AD.

Recent Insights on the Role of Nuclear Receptors in Alzheimer's Disease: Mechanisms and Therapeutic Application

Nuclear receptors (NRs) are ligand-activated transcription factors that regulate a broad array of biological processes, including inflammation, lipid metabolism, cell proliferation, and apoptosis. Among the diverse family of NRs, peroxisome proliferator-activated receptors (PPARs), estrogen receptor (ER), liver X receptor (LXR), farnesoid X receptor (FXR), retinoid X receptor (RXR), and aryl hydrocarbon receptor (AhR) have garnered significant attention for their roles in neurodegenerative diseases, particularly Alzheimer's disease (AD). NRs influence the pathophysiology of AD through mechanisms such as modulation of amyloid-beta (Aβ) deposition, regulation of inflammatory pathways, and improvement of neuronal function. However, the dual role of NRs in AD progression, where some receptors may exacerbate the disease while others offer therapeutic potential, presents a critical challenge for their application in AD treatment. This review explores the functional diversity of NRs, highlighting their involvement in AD-related processes and discussing the therapeutic prospects of NR-targeting strategies. Furthermore, the key challenges, including the necessity for the precise identification of beneficial NRs, detailed structural analysis through molecular dynamics simulations, and further investigation of NR mechanisms in AD, such as tau pathology and autophagy, are also discussed. Collectively, continued research is essential to clarify the role of NRs in AD, ultimately facilitating their potential use in the diagnosis, prevention, and treatment of AD.

Therapeutic potential of chrysin in regulation of interleukin-17 signaling in a repeated intranasal amyloid-beta-induced Alzheimer's disease model

Objective: The aim of the current study was to study the therapeutic potential of chrysin against repeated intranasal amyloid-beta (Aβ)-induced interleukin-17 (IL-17) signaling in a mouse model of AD. Methods: Male BALB/c mice were daily exposed to intranasal Aβ1-42 (10 μg/10 μL) for seven consecutive days. Chrysin was orally administered at doses of 25, 50 and 100 mg kg-1 in 0.5% sodium carboxy methyl cellulose suspension from day 5 of Aβ1-42 administration for seven days. Following the treatment, the memory of the animals was appraised using Morris water maze, novel object recognition and passive avoidance tests. Further, the effects of chrysin on Aβ1-42-induced IL-17 signaling and redox levels were evaluated in the cortex and hippocampus regions of the mouse brain through western blot and immunohistochemistry. Results: The exposure to Aβ1-42 through the intranasal route induced a significant decline in the spatial, learning and cognitive memory of the animals, and most interestingly, exposure to Aβ1-42 triggered IL-17-mediated signaling, which resulted in a significant increase in the expression of IL-17RA, Act1 and TRAF6. Furthermore, Aβ1-42 impaired the tissue redox level and inflammatory cytokines in the mouse brain. Alternatively, treatment with chrysin at 25, 50 and 100 mg kg-1 oral doses alleviated Aβ1-42-mediated memory decline, impaired redox levels and inflammation. Specifically, chrysin downregulated the expression of IL-17 and mediated signaling in the brain regions of the mice. Conclusion: Chrysin was evidenced to be a potent antioxidant and anti-inflammatory agent, clearly showing a protective role against Aβ1-42-induced IL-17-mediated inflammation in the brain of the mice.

Targeting Cytokine-Mediated Inflammation in Brain Disorders: Developing New Treatment Strategies

Cytokine-mediated inflammation is increasingly recognized for playing a vital role in the pathophysiology of a wide range of brain disorders, including neurodegenerative, psychiatric, and neurodevelopmental problems. Pro-inflammatory cytokines such as interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) cause neuroinflammation, alter brain function, and accelerate disease development. Despite progress in understanding these pathways, effective medicines targeting brain inflammation are still limited. Traditional anti-inflammatory and immunomodulatory drugs are effective in peripheral inflammatory illnesses. Still, they face substantial hurdles when applied to the central nervous system (CNS), such as the blood-brain barrier (BBB) and unwanted systemic effects. This review highlights the developing treatment techniques for modifying cytokine-driven neuroinflammation, focusing on advances that selectively target critical cytokines involved in brain pathology. Novel approaches, including cytokine-specific inhibitors, antibody-based therapeutics, gene- and RNA-based interventions, and sophisticated drug delivery systems like nanoparticles, show promise with respect to lowering neuroinflammation with greater specificity and safety. Furthermore, developments in biomarker discoveries and neuroimaging techniques are improving our ability to monitor inflammatory responses, allowing for more accurate and personalized treatment regimens. Preclinical and clinical trial data demonstrate the therapeutic potential of these tailored techniques. However, significant challenges remain, such as improving delivery across the BBB and reducing off-target effects. As research advances, the creation of personalized, cytokine-centered therapeutics has the potential to alter the therapy landscape for brain illnesses, giving patients hope for better results and a higher quality of life.

Alzheimer's disease and infectious agents: a comprehensive review of pathogenic mechanisms and microRNA roles

Alzheimer's Disease (AD) is the most prevalent type of dementia and is characterized by the presence of senile plaques and neurofibrillary tangles. There are various theories concerning the causes of AD, but the connection between viral and bacterial infections and their potential role in the pathogenesis of AD has become a fascinating area of research for the field. Various viruses such as Herpes simplex virus 1 (HSV-1), Epstein-Barr virus (EBV), Cytomegalovirus (CMV), influenza viruses, and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), as well as bacteria such as Chlamydia pneumoniae (CP), Helicobacter pylori (HP), Porphyromonas gingivalis (P. gingivalis), Spirochetes and eukaryotic unicellular parasites (e.g., Toxoplasma gondii), have been linked to AD due to their ability to activate the immune system, induce inflammation and increase oxidative stress, thereby leading to cognitive decline and AD. In addition, microRNAs (miRNAs) might play a crucial role in the pathogenesis mechanisms of these pathogens since they are utilized to target various protein-coding genes, allowing for immune evasion, maintaining latency, and suppressing cellular signaling molecules. Also, they can regulate gene expression in human cells. This article provides an overview of the association between AD and various infectious agents, with a focus on the mechanisms by which these pathogens may be related to the pathogenesis of AD. These findings suggest important areas for further research to be explored in future studies.

Investigating interleukin-8 in Alzheimer's disease: A comprehensive review

Several studies indicate that the development of Alzheimer's disease (AD) has strong interactions with immune mechanisms within the brain, indicating a close association between inflammation in the central nervous system and the progression of neurodegeneration. Despite considerable progress in understanding the inflammatory aspects of AD, several of them remain unresolved. Pro-inflammatory cytokines and microglia are pivotal components in the inflammatory cascade. Among these, the role of interleukin-8 (IL-8) in neurodegeneration seems complex and multifaceted, involving inflammation, neurotoxicity, blood-brain barrier disruption, and oxidative stress, and is still poorly characterized. We conducted a review to describe the evidence of IL-8 involvement in AD. IL-8 is a cytokine known for its proinflammatory properties and typically produced by macrophages, predominantly functions as a chemotactic signal for attracting neutrophils to inflamed sites in the bloodstream. Interestingly, IL-8 is also present in the brain, where it is primarily released by microglia in response to inflammatory signals. This review aims to provide a comprehensive overview of the structure, function, and regulatory mechanisms of IL-8 relevant to AD pathology.

Suppression of MT5-MMP Reveals Early Modulation of Alzheimer's Pathogenic Events in Primary Neuronal Cultures of 5xFAD Mice

We previously reported that membrane-type 5-matrix metalloproteinase (MT5-MMP) deficiency not only reduces pathological hallmarks of Alzheimer's disease (AD) in 5xFAD (Tg) mice in vivo but also impairs interleukin-1 beta (IL-1β)-mediated neuroinflammation and Aβ production in primary Tg immature neural cell cultures after 11 days in vitro. We now investigate the effect of MT5-MMP on incipient pathogenic pathways that are activated in cortical primary cultures at 21-24 days in vitro (DIV), during which time neurons are organized into a functional mature network. Using wild-type (WT), MT5-MMP-/- (MT5-/-), 5xFAD (Tg), and 5xFADxMT5-MMP-/- (TgMT5-/-) mice, we generated primary neuronal cultures that were exposed to IL-1β and/or different proteolytic system inhibitors. We assessed neuroinflammation, APP metabolism, synaptic integrity, and electrophysiological properties using biochemical, imaging and whole-cell patch-clamp approaches. The absence of MT5-MMP impaired the IL-1β-mediated induction of inflammatory genes in TgMT5-/- cells compared to Tg cells. Furthermore, the reduced density of dendritic spines in Tg neurons was also prevented in TgMT5-/- neurons. IL-1β caused a strong decrease in the dendritic spine density of WT neurons, which was prevented in MT5-/- neurons. However, the latter exhibited fewer spines than the WT under untreated conditions. The spontaneous rhythmic firing frequency of the network was increased in MT5-/- neurons, but not in TgMT5-/- neurons, and IL-1β increased this parameter only in Tg neurons. In terms of induced somatic excitability, Tg and TgMT5-/- neurons exhibited lower excitability than WT and MT5-/-, while IL-1β impaired excitability only in non-AD backgrounds. The synaptic strength of miniature global synaptic currents was equivalent in all genotypes but increased dramatically in WT and MT5-/- neurons after IL-1β. MT5-MMP deficiency decreased endogenous and overexpressed C83 and C99 levels but did not affect Aβ levels. C99 appears to be cleared by several pathways, including γ-secretase, the autophagolysosomal system, and also α-secretase, via its conversion to C83. In summary, this study confirms that MT5-MMP is a pivotal factor affecting not only neuroinflammation and APP metabolism but also synaptogenesis and synaptic activity at early stages of the pathology, and reinforces the relevance of targeting MT5-MMP to fight AD.

Modulation of the central nervous system immune response and neuroinflammation via Wnt signaling in health and neurodegenerative diseases

The immune response in the central nervous system (CNS) is a highly specialized and tightly regulated process essential for maintaining neural health and protecting against pathogens and injuries. The primary immune cells within the CNS include microglia, astrocytes, T cells, and B cells. They work together, continuously monitor the CNS environment for signs of infection, injury, or disease, and respond by phagocytosing debris, releasing cytokines, and recruiting other immune cells. In addition to providing neuroprotection, these immune responses must be carefully balanced to prevent excessive inflammation that can lead to neuronal damage and contribute to neurodegenerative diseases. Dysregulated immune responses in the CNS are implicated in various neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Wnt signaling is a crucial pathway in the CNS that regulates various cellular processes critical for brain development, function, and maintenance. Despite enhancing immune responses in the health CNS, dysregulated Wnt signaling exacerbates neuroinflammation in the neurodegenerative brains. This review summarized the role of Wnt signaling in regulating immune response under different conditions. We then examined the role of immune response in healthy brains and during the development of neurodegenerative diseases. We also discussed therapeutic intervention in various neurodegenerative diseases through the modulation of the Wnt signaling pathway and neuroinflammation and highlighted challenges and limitations in current clinical trials.

Effects and mechanisms of APP and its cleavage product Aβ in the comorbidity of sarcopenia and Alzheimer's disease

Sarcopenia and AD are both classic degenerative diseases, and there is growing epidemiological evidence of their comorbidity with aging; however, the mechanisms underlying the biology of their commonality have not yet been thoroughly investigated. APP is a membrane protein that is expressed in tissues and is expressed not only in the nervous system but also in the NMJ and muscle. Deposition of its proteolytic cleavage product, Aβ, has been described as a central component of AD pathogenesis. Recent studies have shown that excessive accumulation and aberrant expression of APP in muscle lead to pathological muscle lesions, but the pathogenic mechanism by which APP and its proteolytic cleavage products act in skeletal muscle is less well understood. By summarizing and analyzing the literature concerning the role, pathogenicity and pathological mechanisms of APP and its cleavage products in the nervous system and muscles, we aimed to explore the intrinsic pathological mechanisms of myocerebral comorbidities and to provide new perspectives and theoretical foundations for the prevention and treatment of AD and sarcopenia comorbidities.

The neuroinflammatory role of microRNAs in Alzheimer's disease: pathological insights to therapeutic potential

Alzheimer's disease (AD) is a neurodegenerative disease and the most common cause of dementia, contributing to around 60-80% of cases. The main pathophysiology of AD is characterized by an abnormal accumulation of protein aggregates extracellularly (beta-amyloid plaques) and intracellularly (neurofibrillary tangles of hyperphosphorylated tau). However, an increasing number of studies have also suggested neuroinflammation may have a crucial role in precipitating the cascade reactions that result in the development of AD neuropathology. In particular, several studies indicate microRNAs (miRNAs) can act as regulatory factors for neuroinflammation in AD, with potential to affect the occurrence and/or progression of AD inflammation by targeting the expression of multiple genes. Therefore, miRNAs may have potential as therapeutic targets for AD, which requires more research. This article will review the existing studies on miRNAs that have been identified to regulate neuroinflammation, aiming to gain further insights into the specific regulatory processes of miRNAs, highlight the diagnostic and therapeutic potential of miRNAs as biomarkers in AD, as well as current challenges, and suggest the further work to bridge the gap in knowledge to utilize miRNAs as therapeutic targets for AD.

Neuroinflammatory Biomarkers in Alzheimer's Disease: From Pathophysiology to Clinical Implications

The identification of neuroinflammation as a critical factor in Alzheimer's disease (AD) has expanded the focus of research beyond amyloid-β and tau pathology. The neuroinflammatory fluid biomarkers GFAP, sTREM2, and YKL-40 have gained attention for their potential in early detection and monitoring of disease progression. Plasma GFAP has demonstrated promise in predicting the conversion from mild cognitive impairment to AD dementia, while sTREM2 highlights microglial activation, although there are conflicting results regarding its dynamics in AD pathogenesis. Advanced imaging techniques, such as PET tracers targeting TSPO and MAO-B, have also been developed to visualize glial activation in vivo, offering spatial and temporal insights into neuroinflammatory processes. However, the clinical implementation of these biomarkers faces challenges due to their lack of specificity, as many of them can be elevated in other conditions. Therapeutic strategies targeting neuroinflammation are emerging, with TREM2-targeting therapies and antidiabetic drugs like GLP-1 receptor agonists showing potential in modulating microglial activity. Nevertheless, the complexity of neuroinflammation, which encompasses both protective and harmful responses, necessitates further research to fully unravel its role and optimize therapeutic approaches for AD.

Novelties on Neuroinflammation in Alzheimer's Disease-Focus on Gut and Oral Microbiota Involvement

Recent studies underscore the role of gut and oral microbiota in influencing neuroinflammation through the microbiota-gut-brain axis, including in Alzheimer's disease (AD). This review aims to provide a comprehensive synthesis of recent findings on the involvement of gut and oral microbiota in the neuroinflammatory processes associated with AD, emphasizing novel insights and therapeutic implications. This review reveals that dysbiosis in AD patients' gut and oral microbiota is linked to heightened peripheral and central inflammatory responses. Specific bacterial taxa, such as Bacteroides and Firmicutes in the gut, as well as Porphyromonas gingivalis in the oral cavity, are notably altered in AD, leading to significant changes in microglial activation and cytokine production. Gut microbiota alterations are associated with increased intestinal permeability, facilitating the translocation of endotoxins like lipopolysaccharides (LPS) into the bloodstream and exacerbating neuroinflammation by activating the brain's toll-like receptor 4 (TLR4) pathways. Furthermore, microbiota-derived metabolites, including short-chain fatty acids (SCFAs) and amyloid peptides, can cross the blood-brain barrier and modulate neuroinflammatory responses. While microbial amyloids may contribute to amyloid-beta aggregation in the brain, certain SCFAs like butyrate exhibit anti-inflammatory properties, suggesting a potential therapeutic avenue to mitigate neuroinflammation. This review not only highlights the critical role of microbiota in AD pathology but also offers a ray of hope by suggesting that modulating gut and oral microbiota could represent a novel therapeutic strategy for reducing neuroinflammation and slowing disease progression.

Blood-Based Biomarkers in Alzheimer's Disease: Advancing Non-Invasive Diagnostics and Prognostics

Alzheimer's disease (AD), the most prevalent form of dementia, is expected to rise dramatically in incidence due to the global population aging. Traditional diagnostic approaches, such as cerebrospinal fluid analysis and positron emission tomography, are expensive and invasive, limiting their routine clinical use. Recent advances in blood-based biomarkers, including amyloid-beta, phosphorylated tau, and neurofilament light, offer promising non-invasive alternatives for early AD detection and disease monitoring. This review synthesizes current research on these blood-based biomarkers, highlighting their potential to track AD pathology and enhance diagnostic accuracy. Furthermore, this review uniquely integrates recent findings on protein-protein interaction networks and microRNA pathways, exploring novel combinations of proteomic, genomic, and epigenomic biomarkers that provide new insights into AD's molecular mechanisms. Additionally, we discuss the integration of these biomarkers with advanced neuroimaging techniques, emphasizing their potential to revolutionize AD diagnostics. Although large-scale validation is still needed, these biomarkers represent a critical advancement toward more accessible, cost-effective, and early diagnostic tools for AD.

Inflammatory aspects of Alzheimer's disease

Alzheimer´s disease (AD) stands out as the most common chronic neurodegenerative disorder. AD is characterized by progressive cognitive decline and memory loss, with neurodegeneration as its primary pathological feature. The role of neuroinflammation in the disease course has become a focus of intense research. While microglia, the brain's resident macrophages, have been pivotal to study central immune inflammation, recent evidence underscores the contributions of other cellular entities to the neuroinflammatory process. In this article, we review the inflammatory role of microglia and astrocytes, focusing on their interactions with AD's core pathologies, amyloid beta deposition, and tau tangle formation. Additionally, we also discuss how different modes of regulated cell death in AD may impact the chronic neuroinflammatory environment. This review aims to highlight the evolving landscape of neuroinflammatory research in AD and underscores the importance of considering multiple cellular contributors when developing new therapeutic strategies.

Mechanistic Approach to Immunity and Immunotherapy of Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a debilitating neurodegenerative condition characterized by progressive cognitive decline and memory loss, affecting millions of people worldwide. Traditional treatments, such as cholinesterase inhibitors and NMDA receptor antagonists, offer limited symptomatic relief without addressing the underlying disease mechanisms. These limitations have driven the development of more potent and effective therapies. Recent advances in immunotherapy present promising avenues for AD treatment. Immunotherapy strategies, including both active and passive approaches, harness the immune system to target and mitigate AD-related pathology. Active immunotherapy stimulates the patient's immune response to produce antibodies against AD-specific antigens, while passive immunotherapy involves administering preformed antibodies or immune cells that specifically target amyloid-β (Aβ) or tau proteins. Monoclonal antibodies, such as aducanumab and lecanemab, have shown potential in reducing Aβ plaques and slowing cognitive decline in clinical trials, despite challenges related to adverse immune responses and the need for precise targeting. This comprehensive review explores the role of the immune system in AD, evaluates the current successes and limitations of immunotherapeutic approaches, and discusses future directions for enhancing the treatment efficacy.

Curcumin: A Golden Approach to Healthy Aging: A Systematic Review of the Evidence

Aging-related disorders pose significant challenges due to their complex interplay of physiological and metabolic factors, including inflammation, oxidative stress, and mitochondrial dysfunction. Curcumin, a natural compound with potent antioxidant and anti-inflammatory properties, has emerged as a promising candidate for mitigating these age-related processes. However, gaps in understanding the precise mechanisms of curcumin's effects and the optimal dosages for different conditions necessitate further investigation. This systematic review synthesizes current evidence on curcumin's potential in addressing age-related disorders, emphasizing its impact on cognitive function, neurodegeneration, and muscle health in older adults. By evaluating the safety, efficacy, and mechanisms of action of curcumin supplementation, this review aims to provide insights into its therapeutic potential for promoting healthy aging. A systematic search across three databases using specific keywords yielded 2256 documents, leading to the selection of 15 clinical trials for synthesis. Here, we highlight the promising potential of curcumin as a multifaceted therapeutic agent in combating age-related disorders. The findings of this review suggest that curcumin could offer a natural and effective approach to enhancing the quality of life of aging individuals. Further research and well-designed clinical trials are essential to validate these findings and optimize the use of curcumin in personalized medicine approaches for age-related conditions.

Unraveling the Triad: Hypoxia, Oxidative Stress and Inflammation in Neurodegenerative Disorders

The mammalian brain's complete dependence on oxygen for ATP production makes it highly susceptible to hypoxia, at high altitudes or in clinical scenarios including anemia or pulmonary disease. Hypoxia plays a crucial role in the development of various brain disorders, such as Alzheimer's, Parkinson's, and other age-related neurodegenerative diseases. On the other hand, a decrease in environmental oxygen levels, such as prolonged stays at high elevations, may have beneficial impacts on the process of ageing and the likelihood of death. Additionally, the utilization of controlled hypoxia exposure could potentially serve as a therapeutic approach for age-related brain diseases. Recent findings indicate that the involvement of HIF-1α and the NLRP3 inflammasome is of significant importance in the development of Alzheimer's disease. HIF-1α serves as a pivotal controller of various cellular reactions to oxygen deprivation, exerting influence on a multitude of physiological mechanisms such as energy metabolism and inflammatory responses. The NLRP3 plays a crucial role in the innate immune system by coordinating the initiation of inflammatory reactions through the assembly of the inflammasome complex. This review examines the information pertaining to the contrasting effects of hypoxia on the brain, highlighting both its positive and deleterious effects and molecular pathways that are involved in mediating these different effects. This study explores potential strategies for therapeutic intervention that focus on restoring cellular balance and reducing neuroinflammation, which are critical aspects in addressing this severe neurodegenerative condition and addresses crucial inquiries that warrant further future investigations.

Elevated protease-activated receptor 4 (PAR4) gene expression in Alzheimer's disease predicts cognitive decline

Platelet activation of protease-activated receptor 4 (PAR4) and thrombin are at the top of a chain of events leading to fibrin deposition, microinfarcts, blood-brain barrier disruption, and inflammation. We evaluated mRNA expression of the PAR4 gene F2RL3 in human brain and global cognitive performance in participants with and without cognitive impairment or dementia. Data were acquired from the Religious Orders Study (ROS) and the Rush Memory and Aging Project (MAP). F2RL3 mRNA was elevated in AD cases and was associated with worse retrospective longitudinal cognitive performance. Moreover, F2RL3 expression interacted with clinical AD diagnosis on longitudinal cognition whereas this relationship was attenuated in individuals without cognitive impairment. Additionally, when adjusting for the effects of AD neuropathology, F2RL3 expression remained a significant predictor of cognitive decline. F2RL3 expression correlated positively with transcript levels of proinflammatory markers including TNFα, IL-1β, NFκB, and fibrinogen α/β/γ. Together, these results reveal that F2RL3 mRNA expression is associated with multiple AD-relevant outcomes and its encoded product, PAR4, may play a role in disease pathogenesis.

Anti-Inflammatory Effects of GPR55 Agonists and Antagonists in LPS-Treated BV2 Microglial Cells

Chronic inflammation is driven by proinflammatory cytokines such as interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and chemokines, such as c-c motif chemokine ligand 2 (CCL2), CCL3, C-X-C motif chemokine ligand 2 (CXCL2), and CXCL10. Inflammatory processes of the central nervous system (CNS) play an important role in the pathogenesis of various neurological and psychiatric disorders like Alzheimer's disease, Parkinson's disease, and depression. Therefore, identifying novel anti-inflammatory drugs may be beneficial for treating disorders with a neuroinflammatory background. The G-protein-coupled receptor 55 (GPR55) gained interest due to its role in inflammatory processes and possible involvement in different disorders. This study aims to identify the anti-inflammatory effects of the coumarin-based compound KIT C, acting as an antagonist with inverse agonistic activity at GPR55, in lipopolysaccharide (LPS)-stimulated BV2 microglial cells in comparison to the commercial GPR55 agonist O-1602 and antagonist ML-193. All compounds significantly suppressed IL-6, TNF-α, CCL2, CCL3, CXCL2, and CXCL10 expression and release in LPS-treated BV2 microglial cells. The anti-inflammatory effects of the compounds are partially explained by modulation of the phosphorylation of p38 mitogen-activated protein kinase (MAPK), p42/44 MAPK (ERK 1/2), protein kinase C (PKC) pathways, and the transcription factor nuclear factor (NF)-κB, respectively. Due to its potent anti-inflammatory properties, KIT C is a promising compound for further research and potential use in inflammatory-related disorders.

Prolyl hydroxylase inhibitor FG-4592 alleviates neuroinflammation via HIF-1/BNIP3 signaling in microglia

BACKGROUND

Neuroinflammation is responsible for neuropsychiatric dysfunction following acute brain injury and neurodegenerative diseases. This study describes how a hypoxia-inducible factor prolyl hydroxylase (HIF-PHD) inhibitor FG-4592 prevents the lipopolysaccharide (LPS)-induced acute neuroinflammation in microglia.

METHODS

The distribution of FG-4592 in mouse brain tissues was determined by collision-induced dissociation tandem mass spectrometry. Microglial activation in the hippocampus was analyzed by immunofluorescence. Moreover, we determined the activation of HIF-1 and nuclear factor-κB (NF-κB) signaling pathways, proinflammatory responses using molecular biological techniques. Transcriptome sequencing and BNIP3 silencing were conducted to explore signaling pathway and molecular mechanisms underlying FG-4592 anti-inflammatory activity.

RESULTS

FG-4592 was transported into the brain tissues and LPS increased its transportation. FG-4592 promoted the expression of HIF-1α and induced the downstream gene transcription in the hippocampus. Administration with FG-4592 significantly inhibited microglial hyperactivation and decreased proinflammatory cytokine levels following LPS treatment in the hippocampus. The LPS-induced inflammatory responses and the NF-κB signaling pathway were also downregulated by FG-4592 pretreatment in microglial cells. Mechanistically, Venn diagram analysis of transcriptomic changes of BV2 cells identified that BNIP3 was a shared and common differentially expressed gene among different treatment groups. FG-4592 markedly upregulated the protein levels of BNIP3 in microglia. Importantly, BNIP3 knockdown aggravated the LPS-stimulated inflammatory responses and partially reversed the protection of FG-4592 against microglial inflammatory signaling and microglial activation in the mouse hippocampus.

CONCLUSIONS

FG-4592 alleviates neuroinflammation through facilitating microglial HIF-1/BNIP3 signaling pathway in mice. Targeting HIF-PHD/HIF-1/BNIP3 axis is a promising strategy for the development of anti-neuroinflammation drugs.

Progesterone Receptor Membrane Component 1 Regulates Cellular Stress Responses and Inflammatory Pathways in Chronic Neuroinflammatory Conditions

Alzheimer's disease (AD) is the leading cause of dementia and is one of the neurodegenerative diseases that are caused by neuronal death due to various triggers. Neuroinflammation plays a critical role in the development of AD. The neuroinflammatory response is manifested by pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α; various chemokines; nitrous oxide; and reactive oxygen species. In this study, we evaluated the relevance of progesterone receptor membrane component 1 (PGRMC1), which is expressed in the brain cells during the induction of neuroinflammation. A lipopolysaccharide (LPS)-induced chronic neuroinflammation model and Pgrmc1 knockdown cells were used to assess the inflammatory cytokine levels, AD-related factors, inflammation-related signaling, and cell death. Pgrmc1 knockout (KO) mice had higher IL-1β levels after treatment with LPS compared with those of wild-type (WT) mice. Furthermore, Pgrmc1 KO mice had higher levels of inflammatory factors, endoplasmic reticulum stress indicators, and AD-associated markers compared with those of WT mice who underwent LPS treatment or not. Finally, these indicators were observed in vitro using U373-MG astrocytes. In conclusion, the loss of PGRMC1 may promote neuroinflammation and lead to AD.

Review of the therapeutic potential of Forsythiae Fructus on the central nervous system: Active ingredients and mechanisms of action

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine has gained significant attention in recent years owing to its multi-component, multi-target, and multi-pathway advantages in treating various diseases. Forsythiae Fructus, derived from the dried fruit of Forsythia suspensa (Thunb.) Vahl, is one such traditional Chinese medicine with numerous in vivo and ex vivo therapeutic effects, including anti-inflammatory, antibacterial, and antiviral properties. Forsythiae Fructus contains more than 200 chemical constituents, with forsythiaside, forsythiaside A, forsythiaside B, isoforsythiaside, forsythin, and phillyrin being the most active ingredients. Forsythiae Fructus exerts neuroprotective effects by modulating various pathways, including oxidative stress, anti-inflammation, NF-κB signaling, 2-AG, Nrf2 signaling, acetylcholinesterase, PI3K-Akt signaling, ferroptosis, gut-brain axis, TLR4 signaling, endoplasmic reticulum stress, PI3K/Akt/mTOR signaling, and PPARγ signaling pathway.

AIM OF THE STUDY

This review aims to highlight the potential therapeutic effects of Forsythiae Fructus on the central nervous system and summarize the current knowledge on the active ingredients of Forsythiae Fructus and their effects on different pathways involved in neuroprotection.

MATERIALS AND METHODS

In this review, we conducted a comprehensive search of databases (PubMed, Google Scholar, Web of Science, China Knowledge Resource Integrated, local dissertations and books) up until June 2023 using key terms such as Forsythia suspensa, Forsythiae Fructus, forsythiaside, isoforsythiaside, forsythin, phillyrin, Alzheimer's disease, Parkinson's disease, ischemic stroke, intracerebral hemorrhage, traumatic brain injury, aging, and herpes simplex virus encephalitis.

RESULTS

Our findings indicate that Forsythiae Fructus and its active ingredients own therapeutic effects on the central nervous system by modulating various pathways, including oxidative stress, anti-inflammation, NF-κB signaling, 2-AG, Nrf2 signaling, acetylcholinesterase, PI3K-Akt signaling, ferroptosis, the gut-brain axis, TLR4 signaling, endoplasmic reticulum stress, PI3K/Akt/mTOR signaling, and PPARγ signaling pathway.

CONCLUSION

Forsythiae Fructus and its active ingredients have demonstrated promising neuroprotective properties. Future in vivo and clinical studies of Forsythiae Fructus and its active ingredients should be conducted to establish precise dosage and standard guidelines for a more effective application in the treatment of neurological disorders.

Silibinin effects on cognitive disorders: Hope or treatment?

Objective

Almost all diseases of the nervous system are related to neuroinflammation, oxidative stress, neuronal death, glia activation, and increased pro-inflammatory cytokines. Cognitive disorders are one of the common complications of nervous system diseases. The role of some plant compounds in reducing or preventing cognitive disorders has been determined. Silibinin is a plant bioflavonoid and exhibits various effects on cognitive functions. This article discusses the different mechanisms of the effect of silibinin on cognitive disorders in experimental studies.

Materials and Methods

Databases, including ISI, , Google Scholar, Scopus, Medline and PubMed, were investigated from 2000 to 2021, using related keywords to find required articles.

Results

Silibinin can improve cognitive disorders by different pathways such as reducing neuroinflammation and oxidative stress, activation of reactive oxygen species- Brain-derived neurotrophic factor- Tropomyosin receptor kinase B (ROS-BDNF-TrkB) pathway in the hippocampus, an increase of dendritic spines in the brain, inhibition of hyperphosphorylation of tau protein and increasing the expression of insulin receptor (IR) and insulin-like growth factor receptor 1 (IGF-1R), inhibiting inflammatory responses and oxidative stress in the hippocampus and amygdala, and decrease of Homovanillic acid/Dopamine (HVA/DA) ratio and 3,4-Dihydroxyphenylacetic acid + Homovanillic acid/Dopamine (DOPAC+ HVA/DA) ratio in the prefrontal cortex and 5-hydroxyindoleacetic acid/5-hydroxytryptamine (5-HIAA/5-HT) ratio in the hippocampus.

Conclusion

These results suggest that silibinin can be considered a therapeutic agent for the symptom reduction of cognitive disorders, and it acts by affecting various mechanisms such as inflammation, programmed cell death, and oxidative stress.

Synthetic and Natural Bioactive Molecules in Balancing the Crosstalk among Common Signaling Pathways in Alzheimer's Disease: Understanding the Neurotoxic Mechanisms for Therapeutic Intervention

The structure and function of the brain greatly rely on different signaling pathways. The wide variety of biological processes, including neurogenesis, axonal remodeling, the development and maintenance of pre- and postsynaptic terminals, and excitatory synaptic transmission, depends on combined actions of these molecular pathways. From that point of view, it is important to investigate signaling pathways and their crosstalk in order to better understand the formation of toxic proteins during neurodegeneration. With recent discoveries, it is established that the modulation of several pathological events in Alzheimer's disease (AD) due to the mammalian target of rapamycin (mTOR), Wnt signaling, 5'-adenosine monophosphate activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), and sirtuin 1 (Sirt1, silent mating-type information regulator 2 homologue 1) are central to the key findings. These include decreased amyloid formation and inflammation, mitochondrial dynamics control, and enhanced neural stability. This review intends to emphasize the importance of these signaling pathways, which collectively determine the fate of neurons in AD in several ways. This review will also focus on the role of novel synthetic and natural bioactive molecules in balancing the intricate crosstalk among different pathways in order to prolong the longevity of AD patients.

Associations of neuroinflammatory IL-6 and IL-8 with brain atrophy, memory decline, and core AD biomarkers - in cognitively unimpaired older adults

Concentrations of pro-inflammatory cytokines -interleukin-6 (IL-6) and interleukin-8 (IL-8) - are increased with age and in Alzheimer's disease (AD). It is not clear whether concentrations of IL-6 and IL-8 in the central nervous system predict later brain and cognitive changes over time nor whether this relationship is mediated by core AD biomarkers. Here, 219 cognitively healthy older adults (62-91 years), with baseline cerebrospinal fluid (CSF) measures of IL-6 and IL-8 were followed over time - up to 9 years - with assessments that included cognitive function, structural magnetic resonance imaging, and CSF measurements of phosphorylated tau (p-tau) and amyloid-β (Aβ-42) concentrations (for a subsample). Higher baseline CSF IL-8 was associated with better memory performance over time in the context of lower levels of CSF p-tau and p-tau/Aβ-42 ratio. Higher CSF IL-6 was related to less CSF p-tau changes over time. The results are in line with the hypothesis suggesting that an up-regulation of IL-6 and IL-8 in the brain may play a neuroprotective role in cognitively healthy older adults with lower load of AD pathology.

A meta-analysis of neurogenic exosomes in the diagnosis of Alzheimer's disease

Background

Alzheimer's disease (AD) is an irreversible and difficult-to-treat neurodegenerative disease. It is necessary to search for reliable biomarkers for the early diagnosis of AD in a timely and effective manner in high-risk or preclinical AD populations. Studies have shown that neurogenic exosomes in the blood can be effectively used as biomarkers for AD.

Objective

In this meta-analysis, we aimed to find reliable biomarkers (Aβ42, T-tau, and P-tau181 in peripheral blood neurogenic exosomes) for the early diagnosis of AD to provide theoretical support for the early diagnosis of high-risk or preclinical AD populations.

Methods

By searching the literature database, relevant studies on AD diagnostic markers were collected. The study period was from April 1, 2012, to April 1, 2022. The average concentrations of Aβ42, T-tau, and P-tau181 in the exosomes of the AD group and healthy control group were compared using RevMan 5.3 software.

Results

A total of 13 studies were screened, including 842 subjects. Meta-analysis showed that the combined SMD value of neurogenic exosome Aβ42 was 1.70 (95% CI = [1.20,2.20], Z = 6.69, P < 0.05). The combined SMD value of T-tau was 1.02 (95% CI = [0.27,1.77], Z = 2.67, P < 0.05). The combined SMD value of P-tau181 was 1.75 (95% CI = [1.16, 2.35], Z = 5.75, P < 0.05). The levels of neurogenic exosomes Aβ42, T-tau, and P-tau181 in AD patients were significantly higher than those in healthy controls.

Conclusion

Aβ42, T-tau, and P-tau181 in blood neurogenic exosomes can be effectively used as biomarkers for AD and can be applied in the diagnosis, screening, prognosis prediction and disease monitoring of AD.

The association of microbial infection and adaptive immune cell activation in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia. Early symptoms include the loss of memory and mild cognitive ability; however, as the disease progresses, these symptoms can present with increased severity manifesting as mood and behaviour changes, disorientation, and a loss of motor/body control. AD is one of the leading causes of death in the UK, and with an ever-increasing ageing society, patient numbers are predicted to rise posing a significant global health emergency. AD is a complex neurophysiological disorder where pathology is characterized by the deposition and aggregation of misfolded amyloid-beta (Aβ)-protein that in-turn promotes excessive tau-protein production which together drives neuronal cell dysfunction, neuroinflammation, and neurodegeneration. It is widely accepted that AD is driven by a combination of both genetic and immunological processes with recent data suggesting that adaptive immune cell activity within the parenchyma occurs throughout disease. The mechanisms behind these observations remain unclear but suggest that manipulating the adaptive immune response during AD may be an effective therapeutic strategy. Using immunotherapy for AD treatment is not a new concept as the only two approved treatments for AD use antibody-based approaches to target Aβ. However, these have been shown to only temporarily ease symptoms or slow progression highlighting the urgent need for newer treatments. This review discusses the role of the adaptive immune system during AD, how microbial infections may be contributing to inflammatory immune activity and suggests how adaptive immune processes can pose as therapeutic targets for this devastating disease.

NEK7 inhibition attenuates Aβ42-induced cognitive impairment by regulating TLR4/NF-κB and the NLRP3 inflammasome in mice

NEK7 is a serine/threonine kinase that regulates cell mitosis and the activation of the nucleotide-binding oligomerization domain-like (NOD-like) receptor thermal protein domain associated protein 3 (NLRP3) inflammasome, and is related to neuroinflammation and neuronal damage. The purpose of this study was to explore the role and mechanism of NEK7 in cognitive impairment in Alzheimer's disease (AD). BV2 cells, a microglia cell line, was treated with Aβ42. NEK7 expression was measured with reverse transcription-quantitative polymerase chain reaction and Western blotting. An apoptosis kit was used to determine the apoptotic rate. APPswe/PS1dE9 (APP/PS1) transgenic mice were used as an in vivo AD model. The experimental mice were infected with sh-NEK7 lentivirus to downregulate NEK7. The Morris water maze was conducted to explore the effect of NEK7 downregulation on cognitive ability. The results showed that Aβ42 significantly upregulated NEK7 in BV2 cells. Silencing NEK7 suppressed the decrease in BV2 viability and the increase in inflammation, oxidative stress and apoptosis induced by Aβ42. NEK7 mediated it effects through the TLR4/NF-κB signalling pathway and the NLRP3 inflammasome. Finally, inhibition of NEK7 alleviated the cognitive impairment in APP/PS1 mice. In conclusion, Silencing NEK7 suppresses Aβ42-induced cell apoptosis, inflammation and oxidative stress, and improves cognitive performance in AD mice. NEK7 may be a potential target for AD treatment.

Repurposing Diltiazem for Its Neuroprotective Anti-Dementia Role against Intra-Cerebroventricular Streptozotocin-Induced Sporadic Alzheimer's Disease-Type Rat Model

Alzheimer's disease (AD) is an age-related neuropsychiatric disorder and a common cause of progressive dementia. Diltiazem (DTZ), the non-dihydropyridine benzothiazepine class of calcium channel blocker (CCB), used clinically in angina and other cardiovascular disorders, has proven neurological benefits. In the present study, the neuroprotective anti-dementia effects of DTZ against intra-cerebroventricular-streptozotocin (ICV-STZ)-induced sporadic AD (SAD)-type rat model was investigated. ICV-STZ-induced cognitive impairments were measured via passive avoidance and Morris water maze tasks. Anti-oxidative enzyme status, pro-inflammatory markers, and amyloid-beta (Aβ) protein expression in rat brain tissues were measured using ELISA kits, Western blotting, and immunostaining techniques. The data revealed that ICV-STZ injection in rats significantly induced cognitive deficits and altered the levels of oxidative and pro-inflammatory markers (p < 0.05~p < 0.001). Treatment with DTZ (10 mg/kg, 20 mg/kg, and 40 mg/kg, p.o.) daily for twenty-one days, 1 h before a single ICV-STZ (3 mg/kg) injection, significantly improved cognitive impairments and ameliorated the ICV-STZ-induced altered nitrite, pro-inflammatory cytokines (TNF-α, and IL-1β) and anti-oxidative enzyme levels (superoxide dismutase, lipid peroxidation, and glutathione). Further, DTZ restored the increased Aβ protein expression in ICV-STZ-induced brain tissue. Considering the results obtained, DTZ might have a potential therapeutic role in treating and managing AD and related dementia pathologies due to its anti-dementia activity in SAD-type conditions in rats induced by ICV-STZ.

The protective effects of sesamol and/or the probiotic, Lactobacillus rhamnosus, against aluminum chloride-induced neurotoxicity and hepatotoxicity in rats: Modulation of Wnt/β-catenin/GSK-3β, JAK-2/STAT-3, PPAR-γ, inflammatory, and apoptotic pathways

Introduction: Aluminium (Al) is accumulated in the brain causing neurotoxicity and neurodegenerative disease like Alzheimer's disease (AD), multiple sclerosis, autism and epilepsy. Hence, attenuation of Al-induced neurotoxicity has become a "hot topic" in looking for an intervention that slow down the progression of neurodegenerative diseases. Objective: Our study aims to introduce a new strategy for hampering aluminum chloride (AlCl3)-induced neurotoxicity using a combination of sesamol with the probiotic bacteria; Lactobacillus rhamnosus (L. rhamnosus) and also to test their possible ameliorative effects on AlCl3-induced hepatotoxicity. Methods: Sprague-Dawley male rats were randomly divided into five groups (n = 10/group) which are control, AlCl3, AlCl3 + Sesamol, AlCl3 + L. rhamnosus and AlCl3 + Sesamol + L. rhamnosus. We surveilled the behavioral, biochemical, and histopathological alterations centrally in the brain and peripherally in liver. Results: This work revealed that the combined therapy of sesamol and L. rhamnosus produced marked reduction in brain amyloid-β, p-tau, GSK-3β, inflammatory and apoptotic biomarkers, along with marked elevation in brain free β-catenin and Wnt3a, compared to AlCl3-intoxicated rats. Also, the combined therapy exerted pronounced reduction in hepatic expressions of JAK-2/STAT-3, inflammatory (TNF-α, IL-6, NF-κB), fibrotic (MMP-2, TIMP-1, α-SMA) and apoptotic markers, (caspase-3), together with marked elevation in hepatic PPAR-γ expression, compared to AlCl3 -intoxicated rats. Behavioral and histopathological assessments substantiated the efficiency of this combined regimen in halting the effect of neurotoxicity. Discussion: Probiotics can be used as an add-on therapy with sesamol ameliorate AlCl3 -mediated neurotoxicity and hepatotoxicity.

Bioinformatic analysis of the SPs and NFTs proteomes unravel putative biomarker candidates for Alzheimer's disease

Aging is the main risk factor for the appearance of age-related neurodegenerative diseases, including Alzheimer's disease (AD). AD is the most common form of dementia, characterized by the presence of senile plaques (SPs) and neurofibrillary tangles (NFTs), the main histopathological hallmarks in AD brains. The core of these deposits are predominantly amyloid fibrils in SPs and hyperphosphorylated Tau protein in NFTs, but other molecular components can be found associated with these pathological lesions. Herein, an extensive literature review was carried out to obtain the SPs and NFTs proteomes, followed by a bioinformatic analysis and further putative biomarker validation. For SPs, 857 proteins were recovered, and, for NFTs, 627 proteins of which 375 occur in both groups and represent the common proteome. Gene Ontology (GO) enrichment analysis permitted the identification of biological processes and the molecular functions most associated with these lesions. Analysis of the SPs and NFTs common proteins unraveled pathways and molecular targets linking both histopathological events. Further, validation of a putative phosphotarget arising from the in silico analysis was performed in serum-derived extracellular vesicles from AD patients. This bioinformatic approach contributed to the identification of putative molecular targets, valuable for AD diagnostic or therapeutic intervention.

Is Drp1 a link between mitochondrial dysfunction and inflammation in Alzheimer's disease?

Recent advances highlight that inflammation is critical to Alzheimer Disease (AD) pathogenesis. Indeed, several diseases characterized by inflammation are considered risk factors for AD, such as type 2 diabetes, obesity, hypertension, and traumatic brain injury. Moreover, allelic variations in genes involved in the inflammatory cascade are risk factors for AD. AD is also characterized by mitochondrial dysfunction, which affects the energy homeostasis of the brain. The role of mitochondrial dysfunction has been characterized mostly in neuronal cells. However, recent data are demonstrating that mitochondrial dysfunction occurs also in inflammatory cells, promoting inflammation and the secretion of pro-inflammatory cytokines, which in turn induce neurodegeneration. In this review, we summarize the recent finding supporting the hypothesis of the inflammatory-amyloid cascade in AD. Moreover, we describe the recent data that demonstrate the link between altered mitochondrial dysfunction and the inflammatory cascade. We focus in summarizing the role of Drp1, which is involved in mitochondrial fission, showing that altered Drp1 activation affects the mitochondrial homeostasis and leads to the activation of the NLRP3 inflammasome, promoting the inflammatory cascade, which in turn aggravates Amyloid beta (Ab) deposition and tau-induced neurodegeneration, showing the relevance of this pro-inflammatory pathway as an early event in AD.

Comparison of oxidative stress parameters, thiol-disulfide homeostasis, and pro-inflammatory cytokines levels in patients with bipolar disorder and their first-degree relatives

BACKGROUND

In this study, we aimed to compare the oxidative stress parameters, thiol-disulfide homeostasis, and plasma pro-inflammatory cytokines levels of patients with bipolar disorder (BD), BD patients' first-degree relatives (FDRs), and the healthy controls (HCs).

METHODS

Thirty-five patients with BD, 35 FDRs of BD, and 35 healthy controls (HCs) were included. The individuals' ages varied from 28 to 58, and the groups were well-matched in terms of age and gender. The total thiol (TT), native thiol (NT), disulfide (DIS), total oxidant status (TOS), total antioxidant status (TAS), IL-1β, IL-6, and TNF-α concentrations were measured from serum samples. The oxidative stress index (OSI) was calculated using mathematical formulas.

RESULTS

TOS was significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons). OSI, DIS, oxidized thiol, and the ratio of thiol oxidation-reduction levels were significantly higher in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). TAS, TT, NT, and reduced thiol levels were significantly lower in both patients with BD and FDRs than HCs (p < 0.01 for all pairwise comparisons). IL-1β, IL-6, and TNF-α were significantly higher in both patients and FDRs than HCs (p < 0.01 for all pairwise comparisons).

LIMITATIONS

Small sample size.

CONCLUSIONS

Early diagnosis is important for treating of bipolar disorder. TT, NT, DIS, TOS, TAS, OSI, IL1-β, IL-6, and TNF-α can be used as potential biomarkers in the early diagnosis and intervention of BD. Furthermore, oxidative/antioxidative markers and plasma pro-inflammatory cytokine parameters may guide the determination of the disease's activity and response to treatment.

Cadmium-promoted thyroid hormones disruption mediates ROS, inflammation, Aβ and Tau proteins production, gliosis, spongiosis and neurodegeneration in rat basal forebrain

Cadmium (Cd) produces cognition decline following single and repeated treatment, although the complete mechanisms are still unrevealed. Basal forebrain (BF) cholinergic neurons innervate the cortex and hippocampus, regulating cognition. Cd single and repeated exposure induced BF cholinergic neuronal loss, partly through thyroid hormones (THs) disruption, which may cause the cognition decline observed following Cd exposure. However, the mechanisms through which THs disruption mediate this effect remain unknown. To research the possible mechanisms through which Cd-induced THs deficiency may mediate BF neurodegeneration, Wistar male rats were treated with Cd for 1- (1 mg/kg) or 28-days (0.1 mg/kg) with or without triiodothyronine (T3, 40 μg/kg/day). Cd exposure promoted neurodegeneration, spongiosis, gliosis and several mechanisms related to these alterations (increased H₂0₂, malondialdehyde, TNF-α, IL-1β, IL-6, BACE1, Aβ and phosphorylated-Tau levels, and decreased phosphorylated-AKT and phosphorylated-GSK-3β levels). T3 supplementation partially reversed the effects observed. Our results show that Cd induces several mechanisms that may be responsible for the neurodegeneration, spongiosis and gliosis observed in the rats' BF, which are partially mediated by a reduction in THs levels. These data may help to explain the mechanisms through which Cd induces BF neurodegeneration, possibly leading to the cognitive decline observed, providing new therapeutic tools to prevent and treat these damages.

Targeting the multifaceted neurotoxicity of Alzheimer's disease by tailored functionalisation of the curcumin scaffold

Simultaneous modulation of multifaceted toxicity arising from neuroinflammation, oxidative stress, and mitochondrial dysfunction represents a valuable therapeutic strategy to tackle Alzheimer's disease. Among the significant hallmarks of the disorder, Aβ protein and its aggregation products are well-recognised triggers of the neurotoxic cascade. In this study, by tailored modification of the curcumin-based lead compound 1, we aimed at developing a small library of hybrid compounds targeting Aβ protein oligomerisation and the consequent neurotoxic events. Interestingly, from in vitro studies, analogues 3 and 4, bearing a substituted triazole moiety, emerged as multifunctional agents able to counteract Aβ aggregation, neuroinflammation and oxidative stress. In vivo proof-of-concept evaluations, performed in a Drosophila oxidative stress model, allowed us to identify compound 4 as a promising lead candidate.

A systematic review of exercise modalities that reduce pro-inflammatory cytokines in humans and animals' models with mild cognitive impairment or dementia

PURPOSE

To investigate which type, frequency, duration, intensity, and volume of chronic exercise might more strongly reduce pro-inflammatory cytokines and enhance anti-inflammatory cytokines in human and animal models with Mild Cognitive Impairment (MCI) or dementia.

DESIGN

A systematic review.

DATA SOURCE

English-language search of 13 electronic databases: Web of Science, PubMed/Medline, Sport Discus, Scopus, Cochrane, Psych Net, Springer, ScienceDirect, Pascal & Francis, Sage journals, Pedro, Google Scholar, and Sage.

INCLUSION CRITERIA

(i) human and animal studies that included exercise, physical activity, or fitness training as an experimental intervention, (ii) studies that addressed MCI, dementia, or AD, (iii) studies that focused on measuring cytokines and/or other inflammatory and/or neuroinflammatory immune markers, (iii) studies that examined inflammatory indicators in blood, CSF (Cerebrospinal Fluid), and brain tissue.

RESULTS

Of the 1290 human and animal studies found, 38 were included for qualitative analysis, 11 human articles, 27 animal articles, and two articles addressing both human and animal protocols. In the animal model, physical exercise decreased pro-inflammatory markers in 70.8 % of the articles and anti-inflammatory cytokines: IL -4, IL -10, IL-4β, IL -10β, and TGF-β in 26 % of articles. Treadmill running, resistance exercise, and swimming exercise reduce pro-inflammatory cytokines and increase anti-inflammatory cytokines. In the human model, 53.9 % of items reduced pro-inflammatory proteins and 23 % increased anti-inflammatory proteins. Cycling exercise, multimodal, and resistance training effectively decreased pro-inflammatory cytokines.

CONCLUSION

In rodent animal models with AD phenotype, treadmill, swimming, and resistance training remain good interventions that can delay various mechanisms of dementia progression. In the human model, aerobic, multimodal, and resistance training are beneficial in both MCI and AD. Multimodal training of moderate to high intensity multimodal exercise is effective for MCI. Voluntary cycling training, moderate- or high-intensity aerobic exercise is effective in mild AD patients.

DYRK1A Inhibitors and Perspectives for the Treatment of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is a chronic neurodegenerative disease and the most common form of dementia, especially in the elderly. Due to the increase in life expectancy, in recent years, there has been an excessive growth in the number of people affected by this disease, causing serious problems for health systems. In recent years, research has been intensified to find new therapeutic approaches that prevent the progression of the disease. In this sense, recent studies indicate that the dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A) gene, which is located on chromosome 21q22.2 and overexpressed in Down syndrome (DS), may play a significant role in developmental brain disorders and early onset neurodegeneration, neuronal loss and dementia in DS and AD. Inhibiting DYRK1A may serve to stop the phenotypic effects of its overexpression and, therefore, is a potential treatment strategy for the prevention of ageassociated neurodegeneration, including Alzheimer-type pathology.

OBJECTIVE

In this review, we investigate the contribution of DYRK1A inhibitors as potential anti-AD agents.

METHODS

A search in the literature to compile an in vitro dataset including IC50 values involving DYRK1A was performed from 2014 to the present day. In addition, we carried out structure-activity relationship studies based on in vitro and in silico data.

RESULTS

molecular modeling and enzyme kinetics studies indicate that DYRK1A may contribute to AD pathology through its proteolytic process, reducing its kinase specificity.

CONCLUSION

further evaluation of DYRK1A inhibitors may contribute to new therapeutic approaches for AD.

The contribution of gut-brain axis to development of neurological symptoms in COVID-19 recovered patients: A hypothesis and review of literature

The gut microbiota undergoes significant alterations in response to viral infections, particularly the novel SARS-CoV-2. As impaired gut microbiota can trigger numerous neurological disorders, we suggest that the long-term neurological symptoms of COVID-19 may be related to intestinal microbiota disorders in these patients. Thus, we have gathered available information on how the virus can affect the microbiota of gastrointestinal systems, both in the acute and the recovery phase of the disease, and described several mechanisms through which this gut dysbiosis can lead to long-term neurological disorders, such as Guillain-Barre syndrome, chronic fatigue, psychiatric disorders such as depression and anxiety, and even neurodegenerative diseases such as Alzheimer's and Parkinson's disease. These mechanisms may be mediated by inflammatory cytokines, as well as certain chemicals such as gastrointestinal hormones (e.g., CCK), neurotransmitters (e.g., 5-HT), etc. (e.g., short-chain fatty acids), and the autonomic nervous system. In addition to the direct influences of the virus, repurposed medications used for COVID-19 patients can also play a role in gut dysbiosis. In conclusion, although there are many dark spots in our current knowledge of the mechanism of COVID-19-related gut-brain axis disturbance, based on available evidence, we can hypothesize that these two phenomena are more than just a coincidence and highly recommend large-scale epidemiologic studies in the future.

Role of pro-inflammatory cytokines in Alzheimer's disease and neuroprotective effects of pegylated self-assembled nanoscaffolds

Neurodegeneration and synaptic loss in Alzheimer's disease (AD) lead to impairment in memory functions. Neuroinflammation causes activation of microglia and astrocytes cells that locally and systemically produces inflammatory cytokines which can serve as early diagnostic markers or therapeutic targets in AD. Pro-inflammatory cytokines (Interleukins (IL-1β, IL-6 and IL-10) and tumor necrosis factor (TNF α)) levels were estimated in serum, cerebral tissue, hepatic tissue, and renal tissue in treatment groups of scopolamine-induced amnesia mice model using ELISA protocol. The results showed that cerebral tissue of AD mice exhibited elevated levels of IL1β, IL6, IL10 and TNFα which indicate contribution of pro-inflammatory cytokines in the progression of AD. A significant reduction in the concentration of IL1β, IL-10 and TNF-α were noticed in serum, cerebral tissue and hepatic tissue of animal group treated with marketed memantine tablet (Admenta), pure memantine drug (MEMp), memantine-poly (lactic-co-glycolic acid) self-assembled nanoscaffolds (MEM-PLGA) SANs, Polyethylene Glycol coated memantine-poly (lactic-co-glycolic acid) self-assembled nanoscaffolds [(PEG-MEM-PLGA) SANs] and Polyethylene Glycol coated memantine-poly [(lactic-co-glycolic acid)] self-assembled nanoscaffolds grafted with Bone Marrow Derived Stem Cell ((PEG-MEM-PLGA) SANs-BMSc), whereas a high level of IL-6 was observed in hepatic tissue, cerebral tissue and renal tissues of normal and AD induced mice which showed the emerging potential of IL-6 cytokines that can trigger either neurons survival after injury or causing neurodegeneration and cell apoptosis. The Neuroregenerative potential of stem cells helps in the proliferation of neuronal cell and thus improves cognition in AD animal model.

The gut microbiota in neurodegenerative diseases: revisiting possible therapeutic targets for cannabidiol

Understanding the pathophysiology of Alzheimer's disease (AD) is essential to improve the efficacy of treatments and, consequently, patients' lives. Unfortunately, traditional therapeutic strategies have not been effective. There is therefore an urgent need to discover or develop alternative treatment strategies. Recently, some pieces of the puzzle appear to emerge: on a hand, the gut microbiota (GM) has gained attention since intestinal dysbiosis aggravates and generates some of the pathological processes of AD; on the other hand, cannabidiol (CBD), a phytocannabinoid, attenuates intestinal inflammation and possesses neuroprotective properties. Intestinal dysbiosis (increased population of proinflammatory bacteria) in AD increases plasma lipopolysaccharide and Aβ peptide levels, both responsible for increasing the permeability of the blood-brain barrier (BBB). A leaky BBB may facilitate the entry of peripheral inflammatory mediators into the central nervous system and ultimately aggravate neuroinflammation and neuronal death due to chronic activation of glial cells. Studies investigating the GM reported a strong relationship between intestinal dysbiosis and AD. In this review we conjecture that the GM is a promising therapeutic target for CBD in the context of AD.

Role of chronic neuroinflammation in neuroplasticity and cognitive function: A hypothesis

OBJECTIVE

Evaluating the efficacy of 3,6'-dithioPomalidomide in 5xFAD Alzheimer's disease (AD) mice to test the hypothesis that neuroinflammation is directly involved in the development of synaptic/neuronal loss and cognitive decline.

BACKGROUND

Amyloid-β (Aβ) or tau-focused clinical trials have proved unsuccessful in mitigating AD-associated cognitive impairment. Identification of new drug targets is needed. Neuroinflammation is a therapeutic target in neurodegenerative disorders, and TNF-α a pivotal neuroinflammatory driver.

NEW HYPOTHESIS

AD-associated chronic neuroinflammation directly drives progressive synaptic/neuronal loss and cognitive decline. Pharmacologically mitigating microglial/astrocyte activation without altering Aβ generation will define the role of neuroinflammation in AD progression.

MAJOR CHALLENGES

Difficulty of TNF-α-lowering compounds reaching brain, and identification of a therapeutic-time window to preserve the beneficial role of neuroinflammatory processes.

LINKAGE TO OTHER MAJOR THEORIES

Microglia/astroglia are heavily implicated in maintenance of synaptic plasticity/function in healthy brain and are disrupted by Aβ. Mitigation of chronic gliosis can restore synaptic homeostasis/cognitive function.

Anti-Inflammatory Activity of Panduratin A against LPS-Induced Microglial Activation

Uncontrolled and excessive microglial activation is known to contribute to inflammation-mediated neurodegeneration. Therefore, reducing neurotoxic microglial activation may serve as a new approach to preventing neurodegeneration. Here, we investigated the anti-inflammatory effects of panduratin A against microglial activation induced by lipopolysaccharides (LPS) in the SIMA9 microglial cell line. We initially examined the anti-inflammatory properties of panduratin A by measuring LPS-induced nitric oxide (NO) production and the levels of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). Panduratin A significantly reduced NO levels and pro-inflammatory cytokines’ production and secretion. In addition, panduratin A enhanced the production of anti-inflammatory cytokines IL-4 and IL-10. The anti-inflammatory effects of panduratin A are related to the suppression of the NF-κB signaling pathway. Together, these results demonstrate the anti-inflammatory properties of panduratin A against LPS-induced microglial activation, suggesting panduratin A has the potential to be further developed as a new agent for the prevention of neuroinflammation-associated neurodegenerative diseases.

The effects and potential of microglial polarization and crosstalk with other cells of the central nervous system in the treatment of Alzheimer's disease

Microglia are resident immune cells in the central nervous system. During the pathogenesis of Alzheimer's disease, stimulatory factors continuously act on the microglia causing abnormal activation and unbalanced phenotypic changes; these events have become a significant and promising area of research. In this review, we summarize the effects of microglial polarization and crosstalk with other cells in the central nervous system in the treatment of Alzheimer's disease. Our literature search found that phenotypic changes occur continuously in Alzheimer's disease and that microglia exhibit extensive crosstalk with astrocytes, oligodendrocytes, neurons, and penetrated peripheral innate immune cells via specific signaling pathways and cytokines. Collectively, unlike previous efforts to modulate microglial phenotypes at a single level, targeting the phenotypes of microglia and the crosstalk with other cells in the central nervous system may be more effective in reducing inflammation in the central nervous system in Alzheimer's disease. This would establish a theoretical basis for reducing neuronal death from central nervous system inflammation and provide an appropriate environment to promote neuronal regeneration in the treatment of Alzheimer's disease.

Site-specific decreases in DNA methylation in replicating cells following exposure to oxidative stress

Oxidative stress is a common feature of inflammation-driven cancers, and it promotes genomic instability and aggressive tumour phenotypes. It is known that oxidative stress transiently modulates gene expression through the oxidation of transcription factors and associated regulatory proteins. Neutrophils are our most abundant white blood cells and accumulate at sites of infection and inflammation. Activated neutrophils produce hypochlorous acid and chloramines, which can disrupt DNA methylation by oxidizing methionine. The goal of the current study was to determine whether chloramine exposure results in sequence-specific modifications in DNA methylation that enable long-term alterations in transcriptional output. Proliferating Jurkat T-lymphoma cells were exposed to sublethal doses of glycine chloramine and differential methylation patterns were compared using Illumina EPIC 850 K bead chip arrays. There was a substantial genome-wide decrease in methylation 4 h after exposure that correlated with altered RNA expression for 24 and 48 h, indicating sustained impacts on exposed cells. A large proportion of the most significant differentially methylated CpG sites were situated towards chromosomal ends, suggesting that these regions are most susceptible to inhibition of maintenance DNA methylation. This may contribute to epigenetic instability of chromosomal ends in rapidly dividing cells, with potential implications for the regulation of telomere length and cellular longevity.