Microglial TLR4/NLRP3 Inflammasome Signaling in Alzheimer's Disease

Decoding NLRP3 Inflammasome Activation in Alzheimer's Disease: A Focus on Receptor Dynamics

Alzheimer's disease (AD) is a leading neurodegenerative disorder marked by progressive cognitive decline and significant neuropsychiatric disturbances. Neuroinflammation, mediated by the NLRP3 inflammasome, is increasingly recognized as a critical factor in AD pathogenesis. The NLRP3 inflammasome, a crucial component of the innate immune system, is activated in response to both pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). In AD, amyloid-beta (Aβ) plaques and tau aggregates act as DAMPs, triggering NLRP3 inflammasome activation in microglia and astrocytes. This activation leads to the production of pro-inflammatory cytokines IL-1β and IL-18, contributing to chronic neuroinflammation and neuronal death. This review explores the intricate mechanisms involved in NLRP3 activation, with a particular focus on TREM-2, Msn Kinase MINK, NF-κB, Toll-like receptors, and P2X7 receptors. Understanding these mechanisms offers insight into the multifaceted regulation of the NLRP3 inflammasome and its impact on AD pathology. By elucidating the roles of TREM-2, MINK1, NF-κB, TLRs, and P2X7 receptors, this review highlights potential therapeutic targets for modulating NLRP3 activity. Targeting these pathways could offer novel strategies for mitigating neuroinflammation and slowing the progression of AD. The interplay between these receptors and signaling pathways underscores the complexity of NLRP3 inflammasome regulation and its significance in AD, providing a foundation for future research aimed at developing effective therapeutic interventions.

Protection of Green Tea Polyphenols against Neurodegenerative Diseases: Evidence and Possible Mechanisms

Aging is a major risk factor for neurodegenerative diseases. With aging of the global population, the prevalence of neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), has increased worldwide. Unfortunately, the available therapeutic options for these neurodegenerative diseases are limited, most of which only provide symptomatic relief and have potentially serious side effects. Epidemiological studies have shown that green tea consumption is associated with a lower prevalence of cognitive decline and decreased risk of AD and PD, providing an attractive preventive and therapeutic option. Polyphenols are major bioactive components in green tea, which contribute to the beneficial effects of green tea. Accumulating data suggest that green tea polyphenols (GTPs) have neuroprotective properties that inhibit the pathological development of neurodegenerative diseases; however, the underlying mechanisms are not yet completely understood. This paper reviews both in vitro and in vivo evidence that demonstrates the neuroprotective effects of GTPs against neurodegenerative diseases, with the main focus on AD and PD, and summarizes the possible molecular mechanisms by which GTPs impede the progression of neurodegeneration. In particular, this review highlights the modulation of GTPs on the common mechanisms involved in pathogenesis of neurodegenerative diseases, including oxidative stress-mediated neuronal toxicity, impaired proteostasis, and metal ion dyshomeostasis. The potential of using GTPs in the intervention of neurodegenerative diseases is also discussed, hopefully, providing useful insights into novel preventive and therapeutic strategies for these diseases.

Neuroinflammation-A Crucial Factor in the Pathophysiology of Depression-A Comprehensive Review

Depression is a multifactorial psychiatric condition with complex pathophysiology, increasingly linked to neuroinflammatory processes. The present review explores the role of neuroinflammation in depression, focusing on glial cell activation, cytokine signaling, blood-brain barrier dysfunction, and disruptions in neurotransmitter systems. The article highlights how inflammatory mediators influence brain regions implicated in mood regulation, such as the hippocampus, amygdala, and prefrontal cortex. The review further discusses the involvement of the hypothalamic-pituitary-adrenal (HPA) axis, oxidative stress, and the kynurenine pathway, providing mechanistic insights into how chronic inflammation may underlie emotional and cognitive symptoms of depression. The bidirectional relationship between inflammation and depressive symptoms is emphasized, along with the role of peripheral immune responses and systemic stress. By integrating molecular, cellular, and neuroendocrine perspectives, this review supports the growing field of immunopsychiatry and lays the foundation for novel diagnostic biomarkers and anti-inflammatory treatment approaches in depression. Further research in this field holds promise for developing more effective and personalized interventions for individuals suffering from depression.

Gegen Qinlian Decoction improves Alzheimer's disease through TLR4/NF-κB/NLRP3 pathway

OBJECTIVE

Alzheimer's disease (AD) is a neurodegenerative disease that leads to dementia, but effective treatments are lacking. This study aims to evaluate the therapeutic effects of Gegen Qinlian Decoction (GGQLD) on AD and investigate the underlying mechanisms.

METHODS

Using network pharmacology and bioinformatics, we identified 376 active ingredients of GGQLD and 427 drug targets. Among these, 7 potential targets (CASP1, MKI67, NFKB1, TLR4, NLRP3, IL1B, and AKT1) were identified as intersecting targets of both GGQLD and AD. Functional enrichment analysis revealed that GGQLD regulates pyroptosis-related pathways. In vivo, GGQLD was administered to AD rat models to assess its effects on spatial learning, memory, and brain tissue injury.

RESULTS

GGQLD significantly reduced latency time by 40 % and increased platform crossings by 60 % in AD rats, demonstrating improved spatial learning and memory abilities. It also reduced hippocampal tissue damage and abnormal Aβ deposition. Mechanistically, GGQLD downregulated pyroptosis-related targets (TLR4, NF-κB, NLRP3, IL-1β, and Caspase-1), which were significantly upregulated in AD. ROC analysis demonstrated strong diagnostic significance for these genes, with AUC values exceeding 0.70. Functional enrichment and KEGG analysis further indicated that GGQLD exerts its therapeutic effects through multiple pathways, particularly the NOD-like receptor pathway, Necroptosis, and NF-kappa B pathway.

CONCLUSIONS

This study demonstrates that GGQLD improves spatial learning, reduces brain tissue damage, and alleviates inflammation in AD through the regulation of pyroptosis-related pathways, providing evidence for its potential as a therapeutic agent for AD.

Targeting NLRP3 signaling with a novel sulfonylurea compound for the treatment of vascular cognitive impairment and dementia

Background

As a key inflammatory factor, the nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome plays a crucial role in neuroinflammation and the progression of neurodegenerative diseases. Dysregulation of NLRP3 signaling can trigger various inflammatory responses in the brain, contributing to the development of neurodegenerative diseases such as ischemic stroke, vascular dementia (VaD), Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). Therefore, the NLRP3 signaling pathway is a promising therapeutic target for the treatment of neurodegenerative diseases, including VaD.

Methods

In this study, we investigated the therapeutic effects of a synthetic sulfonylurea NLRP3 inhibitor, AMS-17, in a VaD mouse model using bilateral common carotid artery stenosis (BCAS) and elucidated the underlying mechanisms. All mice were randomly divided into three groups: Sham, VaD + Vehicle, and VaD + AMS-17. Cognitive function was assessed using the Y-maze and Morris water maze (MWM) on the 50th day after BCAS. Brain sections and blood serum samples were collected for biomarker analysis and immunohistochemistry. Neurodegeneration, expressions of the molecules involved in the NLRP3 signaling pathways, tight junction proteins, and myelination were assessed using western blotting and immunofluorescence (IF). The levels of Interleukin-1 beta (IL-1β), Tumor Necrosis Factor-alpha (TNF-α) and Interleukin-4 (IL-4) in the blood were measured using ELISA.

Results

AMS-17 treatment improved cognitive function, enhanced blood-brain barrier (BBB) integrity, and promoted remyelination in VaD mice. Additionally, AMS-17 reduced neurodegeneration and decreased the expression of NLRP3 and its associated proteins, Apoptosis-associated speck-like protein (ASC), and cleaved caspase-1 in the brain. It also lowered pro-inflammatory TNF-α and IL-1β levels, while increasing the anti-inflammatory IL-4 level in the blood.

Conclusions

The findings of this study provide the first promising evidence for the use of AMS-17 in VaD treatment in mice. This study introduces AMS-17 as a novel chemical scaffold with NLRP3 inhibitory activity, which can be further developed for the treatment of VaD in humans.

Salidroside: An Overview of Its Promising Potential and Diverse Applications

Salidroside, a phenolic compound isolated from various Rhodiola plants, is the principal active constituent of Traditional Chinese Medicine known for its adaptogenic properties. Due to the challenging environment of Rhodiola species, such as high altitude, high radiation, drought, and hypoxia, the source of salidroside is scarce. However, numerous studies have shown that salidroside has a range of biological activities, including cardiovascular and central nervous system activity, and anti-hypoxia, anti-inflammatory, and anti-aging activities. Although previous studies have partially summarized the pharmacological effects of salidroside, the overall pharmacological effects have not been analyzed. Hence, this review will systematically summarize the isolation, purification, synthesis, derivatization, pharmacological activity, pharmacokinetics, clinical application, and safety of salidroside. It is expected to provide new insights for the further research and pharmaceutical development of salidroside.

Aβ1-42 promotes microglial activation and apoptosis in the progression of AD by binding to TLR4

Alzheimer's disease (AD) is one of the most common age-related neurodegenerative diseases and the most devastating form of senile dementia. It has a complex mechanism and no effective treatment. Exploring the pathogenesis of AD and providing ideas for treatment can effectively improve the prognosis of AD. Microglia were incubated with β-amyloid protein 1-42 (Aβ1-42) to construct an AD cell model. After microglia were activated, cell morphology changed, the expression level of inflammatory factors increased, cell apoptosis was promoted, and the expression of microtubule-associated protein (Tau protein) and related proteins increased. By up-regulating and down-regulating Toll-like receptor 4 (TLR4), the cells were divided into TLR4 knockdown negative control group(Lv-NC group), TLR4 knockdown group(Lv-TLR4 group), TLR4 overexpression negative control group(Sh-NC group), and TLR4 overexpression group(Sh-TLR4 group). The expression of inflammatory factors was detected again. It was found that compared with the Lv-NC group, the expression of various inflammatory factors in the Lv-TLR4 group decreased, cell apoptosis was inhibited, and the expression of Tau protein and related proteins decreased. Compared with the Sh-NC group, the expression of inflammatory factors in the Sh-TLR4 group increased, cell apoptosis was promoted, and the expression of Tau protein and related proteins increased. These results indicate that Aβ1-42 may promote microglial activation and apoptosis by binding to TLR4. Reducing the expression of TLR4 can reduce the occurrence of inflammatory response in AD cells and slow down cell apoptosis. Therefore, TLR4 is expected to become a new target for the prevention and treatment of AD.

Deep-Learning-Driven Discovery of SN3-1, a Potent NLRP3 Inhibitor with Therapeutic Potential for Inflammatory Diseases

The NLRP3 inflammasome plays a central role in the pathogenesis of various intractable human diseases, making it an urgent target for therapeutic intervention. Here, we report the development of SN3-1, a novel orally potent NLRP3 inhibitor, designed through a lead compound strategy centered on deep-learning-based molecular generative models. Our strategy enables rapid fragment enumeration and takes into account the synthetic accessibility of the compounds, thereby significantly enhancing the optimization of lead compounds and facilitating the discovery of potent inhibitors. X-ray crystallography provided insights into the SN3-1 inhibitory mechanism. SN3-1 has shown a favorable safety profile in both acute and chronic toxicity assessments and exhibits robust pharmacokinetic properties. Furthermore, SN3-1 demonstrated significant therapeutic efficacy in various disease models characterized by NLRP3 activation. This study introduces a potent candidate for developing NLRP3 inhibitors and significantly expands the repertoire of tools available for the discovery of novel inhibitors.

The neuroinflammatory role of microglia in Alzheimer's disease and their associated therapeutic targets

INTRODUCTION

Alzheimer's disease (AD), the main cause of dementia, is characterized by synaptic loss and neurodegeneration. Amyloid-β (Aβ) accumulation, hyperphosphorylation of tau protein, and neurofibrillary tangles (NFTs) in the brain are considered to be the initiating factors of AD. However, this hypothesis falls short of explaining many aspects of AD pathogenesis. Recently, there has been mounting evidence that neuroinflammation plays a key role in the pathophysiology of AD and causes neurodegeneration by over-activating microglia and releasing inflammatory mediators.

METHODS

PubMed, Web of Science, EMBASE, and MEDLINE were used for searching and summarizing all the recent publications related to inflammation and its association with Alzheimer's disease.

RESULTS

Our review shows how inflammatory dysregulation influences AD pathology as well as the roles of microglia in neuroinflammation, the possible microglia-associated therapeutic targets, top neuroinflammatory biomarkers, and anti-inflammatory drugs that combat inflammation.

CONCLUSION

In conclusion, microglial inflammatory reactions are important factors in AD pathogenesis and need to be discussed in more detail for promising therapeutic strategies.

Macrophage migration inhibitor factor (MIF): Potential role in cognitive impairment disorders

Macrophage migration inhibitory factor (MIF) is a cytokine in the immune system, participated in both innate and adaptive immune responses. Except from immune cells, MIF is also secreted by a variety of non-immune cells, including hematopoietic cells, endothelial cells (ECs), and neurons. MIF plays a crucial role in various diseases, such as sepsis, rheumatoid arthritis, acute kidney injury, and neurodegenerative diseases. The role of MIF in the neuropathogenesis of cognitive impairment disorders is emphasized, as it recruits multiple inflammatory mediators, leading to activating microglia or astrocyte-derived neuroinflammation. Furthermore, it contributes to the cell death of neurons and ECs with the binding of apoptosis-inducing factor (AIF) through parthanatos-associated apoptosis-inducing factor nuclease (PAAN) / MIF pathway. This review comprehensively delves into the relationship between MIF and the neuropathogenesis of cognitive impairment disorders, providing a series of emerging MIF-targeted pharmaceuticals as potential treatments for cognitive impairment disorders.

Advancements in Predictive Medicine: NLRP3 Inflammasome Inhibitors and AI-Driven Predictive Health Analytics

Recent advancements in predictive medicine are significantly reshaping the field, primarily through developing novel NLRP3 inflammasome inhibitors and applying AI-driven predictive health analytics. NLRP3 inflammasome inhibitors offer new therapeutic strategies for treating inflammatory and neurodegenerative diseases. Concurrently, AI's role in predictive health analytics marks a transformative shift in disease management and personalized healthcare. By analyzing complex biomarker data, AI provides crucial insights into individual health trajectories, enabling early interventions and customized treatment plans. This convergence of cutting-edge therapies and AI technology heralds a new era in precision medicine and personalized healthcare strategies.

A review of the mechanisms of abnormal ceramide metabolism in type 2 diabetes mellitus, Alzheimer's disease, and their co-morbidities

The global prevalence of type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) is rapidly increasing, revealing a strong association between these two diseases. Currently, there are no curative medication available for the comorbidity of T2DM and AD. Ceramides are structural components of cell membrane lipids and act as signal molecules regulating cell homeostasis. Their synthesis and degradation play crucial roles in maintaining metabolic balance in vivo, serving as important mediators in the development of neurodegenerative and metabolic disorders. Abnormal ceramide metabolism disrupts intracellular signaling, induces oxidative stress, activates inflammatory factors, and impacts glucose and lipid homeostasis in metabolism-related tissues like the liver, skeletal muscle, and adipose tissue, driving the occurrence and progression of T2DM. The connection between changes in ceramide levels in the brain, amyloid β accumulation, and tau hyper-phosphorylation is evident. Additionally, ceramide regulates cell survival and apoptosis through related signaling pathways, actively participating in the occurrence and progression of AD. Regulatory enzymes, their metabolites, and signaling pathways impact core pathological molecular mechanisms shared by T2DM and AD, such as insulin resistance and inflammatory response. Consequently, regulating ceramide metabolism may become a potential therapeutic target and intervention for the comorbidity of T2DM and AD. The paper comprehensively summarizes and discusses the role of ceramide and its metabolites in the pathogenesis of T2DM and AD, as well as the latest progress in the treatment of T2DM with AD.

Therapeutic Effects of Arctiin on Alzheimer's Disease-like Model in Rats by Reducing Oxidative Stress, Inflammasomes and Fibrosis

BACKGROUND

Alzheimer's disease (AD) affects approximately 50 million people globally and is expected to triple by 2050. Arctiin is a lignan found in the Arctium lappa L. plant. Arctiin possesses anti-proliferative, antioxidative and anti-adipogenic.

OBJECTIVES

We aimed to explore the potential therapeutic effects of Arctiin on rats with AD by evaluating the expression of TLR4, NLRP3, STAT3, TGF-β, cyclin D1, and CDK2.

METHODS

AD was induced in rats by administering 70 mg/kg of aluminum chloride through intraperitoneal injection daily for six weeks. After inducing AD, some rats were treated with 25 mg/kg of Arctiin daily for three weeks through oral gavage. Furthermore, to examine the brain tissue structure, hippocampal sections were stained with hematoxylin/eosin and anti-TLR4 antibodies. The collected samples were analyzed for gene expression and protein levels of TLR4, NLRP3, STAT3, TGF-β, cyclin D1, and CDK2.

RESULTS

In behavioral tests, rats showed a significant improvement in their behavior when treated with Arctiin. Microimages stained with hematoxylin/eosin showed that Arctiin helped to improve the structure and cohesion of the hippocampus, which was previously impaired by AD. Furthermore, Arctiin reduced the expression of TLR4, NLRP3, STAT3, TGF-β, cyclin D1, and CDK2.

CONCLUSION

Arctiin can enhance rats' behavior and structure of the hippocampus in AD rats. This is achieved through its ability to reduce the expression of both TLR4 and NLRP3, hence inhibiting the inflammasome pathway. Furthermore, Arctiin can improve tissue fibrosis by regulating STAT3 and TGF-β. Lastly, it can block the cell cycle proteins cyclin D1 and CDK2.