The Pivotal Role of NF-kB in the Pathogenesis and Therapeutics of Alzheimer’s Disease

Gamma-glutamyl transferase 5 overexpression in cerebrovascular endothelial cells improves brain pathology, cognition, and behavior in APP/PS1 mice

JOURNAL/nrgr/04.03/01300535-202502000-00030/figure1/v/2024-05-28T214302Z/r/image-tiff In patients with Alzheimer's disease, gamma-glutamyl transferase 5 (GGT5) expression has been observed to be downregulated in cerebrovascular endothelial cells. However, the functional role of GGT5 in the development of Alzheimer's disease remains unclear. This study aimed to explore the effect of GGT5 on cognitive function and brain pathology in an APP/PS1 mouse model of Alzheimer's disease, as well as the underlying mechanism. We observed a significant reduction in GGT5 expression in two in vitro models of Alzheimer's disease (Aβ1-42-treated hCMEC/D3 and bEnd.3 cells), as well as in the APP/PS1 mouse model. Additionally, injection of APP/PS1 mice with an adeno-associated virus encoding GGT5 enhanced hippocampal synaptic plasticity and mitigated cognitive deficits. Interestingly, increasing GGT5 expression in cerebrovascular endothelial cells reduced levels of both soluble and insoluble amyloid-β in the brains of APP/PS1 mice. This effect may be attributable to inhibition of the expression of β-site APP cleaving enzyme 1, which is mediated by nuclear factor-kappa B. Our findings demonstrate that GGT5 expression in cerebrovascular endothelial cells is inversely associated with Alzheimer's disease pathogenesis, and that GGT5 upregulation mitigates cognitive deficits in APP/PS1 mice. These findings suggest that GGT5 expression in cerebrovascular endothelial cells is a potential therapeutic target and biomarker for Alzheimer's disease.

Targeting epigenetic mechanisms in amyloid-β-mediated Alzheimer's pathophysiology: unveiling therapeutic potential

Alzheimer's disease is a prominent chronic neurodegenerative condition characterized by a gradual decline in memory leading to dementia. Growing evidence suggests that Alzheimer's disease is associated with accumulating various amyloid-β oligomers in the brain, influenced by complex genetic and environmental factors. The memory and cognitive deficits observed during the prodromal and mild cognitive impairment phases of Alzheimer's disease are believed to primarily result from synaptic dysfunction. Throughout life, environmental factors can lead to enduring changes in gene expression and the emergence of brain disorders. These changes, known as epigenetic modifications, also play a crucial role in regulating the formation of synapses and their adaptability in response to neuronal activity. In this context, we highlight recent advances in understanding the roles played by key components of the epigenetic machinery, specifically DNA methylation, histone modification, and microRNAs, in the development of Alzheimer's disease, synaptic function, and activity-dependent synaptic plasticity. Moreover, we explore various strategies, including enriched environments, exposure to non-invasive brain stimulation, and the use of pharmacological agents, aimed at improving synaptic function and enhancing long-term potentiation, a process integral to epigenetic mechanisms. Lastly, we deliberate on the development of effective epigenetic agents and safe therapeutic approaches for managing Alzheimer's disease. We suggest that addressing Alzheimer's disease may require distinct tailored epigenetic drugs targeting different disease stages or pathways rather than relying on a single drug.

Taming neuroinflammation in Alzheimer's disease: The protective role of phytochemicals through the gut-brain axis

Alzheimer's disease (AD) is a progressive degenerative neurological condition characterized by cognitive decline, primarily affecting memory and logical thinking, attributed to amyloid-β plaques and tau protein tangles in the brain, leading to neuronal loss and brain atrophy. Neuroinflammation, a hallmark of AD, involves the activation of microglia and astrocytes in response to pathological changes, potentially exacerbating neuronal damage. The gut-brain axis is a bidirectional communication pathway between the gastrointestinal and central nervous systems, crucial for maintaining brain health. Phytochemicals, natural compounds found in plants with antioxidant and anti-inflammatory properties, such as flavonoids, curcumin, resveratrol, and quercetin, have emerged as potential modulators of this axis, suggesting implications for AD prevention. Intake of phytochemicals influences the gut microbial composition and its metabolites, thereby impacting neuroinflammation and oxidative stress in the brain. Consumption of phytochemical-rich foods may promote a healthy gut microbiota, fostering the production of anti-inflammatory and neuroprotective substances. Early dietary incorporation of phytochemicals offers a non-invasive strategy for modulating the gut-brain axis and potentially reducing AD risk or delaying its onset. The exploration of interventions targeting the gut-brain axis through phytochemical intake represents a promising avenue for the development of preventive or therapeutic strategies against AD initiation and progression.

Pterostilbene Ameliorates Cognitive Impairment in Polycystic Ovary Syndrome Rat Model through Improving Insulin Resistance via the IRS-1/PI3K/Akt/GSK-3β Pathway: A Comparative Study with Metformin

Polycystic ovary syndrome (PCOS) is an intricate endocrine disorder that targets millions of women globally. Recent research has drawn attention to its association with cognitive impairment and Alzheimer's disease (AD) risk, yet the exact mechanism remains elusive. This study aimed to explore the potential role of PCOS-associated insulin resistance (IR) and inflammation in linking PCOS to AD pathogenesis. It additionally investigated the therapeutic merits of pterostilbene (PTS) in ameliorating PCOS and associated cognitive deficits in comparison to metformin (MET). Rats were divided into five groups; vehicle group, PTS group [30 mg/kg, per os (p.o.) for 13 days], and the remaining three groups received letrozole (1 mg/kg, p.o. for 21 days) to represent the PCOS, PCOS + MET (300 mg/kg, p.o. for 13 days), and PCOS + PTS groups, respectively. Behavioral tests were conducted, along with a histopathological investigation of brains and ovaries. Assessment of serum hormonal profile and hippocampal IRS-1/PI3K/AKT/GSK-3β insulin signaling pathway components were performed. PTS rats exhibited improved insulin sensitivity and hormonal profile, besides enhanced neurobehavioral tests performance and histopathological findings. These effects may be attributed to modulation of the IRS-1/PI3K/AKT/GSK-3β pathway, reducing GSK-3β activity, and mitigating Tau hyperphosphorylation and Aβ accumulation in the brain. Likewise, PTS attenuated nuclear factor kappa B-mediated inflammation and reversed AChE elevation, suggesting multifaceted neuroprotective effects. Comparatively, PTS showed outcomes similar to those of MET in most parameters. The obtained findings validated that dysregulated insulin signaling in PCOS rats detrimentally affects cognitive function, which is halted by PTS, unveiling the potential of PTS as a novel therapy for PCOS and related cognitive deficits.

Emerging paradigms in Alzheimer's Therapy

Alzheimer's disease is a neurodegenerative disorder that affects elderly, and its incidence is continuously increasing across the globe. Unfortunately, despite decades of research, a complete cure for Alzheimer's disease continues to elude us. The current medications are mainly symptomatic and slow the disease progression but do not result in reversal of all disease pathologies. The growing body of knowledge on the factors responsible for the onset and progression of the disease has resulted in the identification of new targets that could be targeted for treatment of Alzheimer's disease. This has opened new vistas for treatment of Alzheimer's disease that have moved away from chemotherapeutic agents modulating a single target to biologics and combinations that acted on multiple targets thereby offering better therapeutic outcomes. This review discusses the emerging directions in therapeutic interventions against Alzheimer's disease highlighting their merits that promise to change the treatment paradigm and challenges that limit their clinical translation.

The regulating effect of curcumin on NF-κB pathway in neurodegenerative diseases: a review of the underlying mechanisms

Neurodegenerative diseases are part of the central nervous system (CNS) disorders that indicate their presence with neuronal loss, neuroinflammation, and increased oxidative stress. Several pathophysiological factors and biomarkers are involved in this inflammatory process causing these neurological disorders. The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) is an inflammation element, which induced transcription and appears to be one of the important players in physiological procedures, especially nervous disorders. NF-κB can impact upon series of intracellular actions and induce or inhibit many inflammation-related pathways. Multiple reports have focused on the modification of NF-κB activity, controlling its expression, translocation, and signaling pathway in neurodegenerative disorders and injuries like Alzheimer's disease (AD), spinal cord injuries (SCI), and Parkinson's disease (PD). Curcumin has been noted to be a popular anti-oxidant and anti-inflammatory substance and is the foremost natural compound produced by turmeric. According to various studies, when playing an anti-inflammatory role, it interacts with several modulating proteins of long-standing disease signaling pathways and has an unprovocative consequence on pro-inflammatory cytokines. This review article determined to figure out curcumin's role in limiting the promotion of neurodegenerative disease via influencing the NF-κB signaling route. Preclinical studies were gathered from plenty of scientific platforms including PubMed, Scopus, Cochrane, and Google Scholar to evaluate this hypothesis. Extracted findings from the literature review explained the repressing impact of Curcumin on the NF-κB signaling pathway and, occasionally down-regulating the cytokine expression. Yet, there is an essential need for further analysis and specific clinical experiments to fully understand this subject.

An antagonist-based two-photon fluorogenic probe for imaging metabotropic glutamate receptor 5 in neuronal cells

The expression of metabotropic glutamate receptor 5 (mGluR5) is subject to developmental regulation and undergoes significant changes in neuropsychiatric disorders and diseases. Visualizing mGluR5 by fluorescence imaging is a highly desired innovative technology for biomedical applications. Nevertheless, there are substantial problems with the chemical probes that are presently accessible. In this study, we have successfully developed a two-photon fluorogenic probe, mGlu-5-TP, based on the structure of mGluR5 antagonist 6-methyl-2-(phenylethynyl)pyridine (MPEP). Due to this antagonist-based probe selectively recognizes mGluR5, high expression of mGluR5 on living SH-SY5Y human neuroblastoma cells has been detected during intracellular inflammation triggered by lipopolysaccharides (LPS). Of particular significance, the probe can be employed along with two-photon fluorescence microscopy to enable real-time visualization of the mGluR5 in Aβ fiber-treated neuronal cells, thereby establishing a connection to the progression of Alzheimer's disease (AD). These results revealed that the probe can be a valuable imaging tool for studying mGluR5-related diseases in the nervous system.

Therapeutic potential of plant-derived natural compounds in Alzheimer's disease: Targeting microglia-mediated neuroinflammation

Microglia are resident immune cells of the central nervous system (CNS) with roles in sensing, housekeeping, and defense. Exploring the role of microglia in the occurrence and development of Alzheimer's disease (AD) and the possible therapeutic mechanism of plant-derived natural compounds (PDNCs) that regulate microglia-associated neuroinflammation may potentially help in elucidating the pathogenesis of AD and provide novel insights for its treatment. This review explores the role of abnormal microglial activation and its dominant neuroinflammatory response, as well as the activation of their target receptors and signaling pathways in AD pathogenesis. Additionally, we report an update on the potential pharmacological mechanisms of multiple PDNCs in modulating microglia-associated neuroinflammation in AD treatment. Dysregulated activation of microglial receptors and their downstream pathways impaired immune homeostasis in animal models of AD. Multiple signaling pathways, such as mitogen-activated protein kinase (MAPK), nuclear factor kappa light chain enhancer of activated B cells (NF-κB), and Toll-like receptors, play important roles in microglial activation and can exacerbate microglia-mediated neuroinflammation. PDNCs, such as magnolol, stigmasterol, matrine, naringenin, naringin, and resveratrol, can delay the progression of AD by inhibiting the proinflammatory receptors of microglia, activating its anti-inflammatory receptors, regulating the receptors related to β-amyloid (Aβ) clearance, reversing immune dysregulation, and maintaining the immune homeostasis of microglial downstream pathways. This review summarizes the mechanisms by which microglia cause chronic inflammation in AD and evaluates the beneficial effects of PDNCs on immune regulation in AD by regulating microglial receptors and their downstream pathways.

Microglia and Astrocytes in Alzheimer's Disease: Significance and Summary of Recent Advances

Alzheimer's disease, one of the most common forms of dementia, is characterized by a slow progression of cognitive impairment and neuronal loss. Currently, approved treatments for AD are hindered by various side effects and limited efficacy. Despite considerable research, practical treatments for AD have not been developed. Increasing evidence shows that glial cells, especially microglia and astrocytes, are essential in the initiation and progression of AD. During AD progression, activated resident microglia increases the ability of resting astrocytes to transform into reactive astrocytes, promoting neurodegeneration. Extensive clinical and molecular studies show the involvement of microglia and astrocyte-mediated neuroinflammation in AD pathology, indicating that microglia and astrocytes may be potential therapeutic targets for AD. This review will summarize the significant and recent advances of microglia and astrocytes in the pathogenesis of AD in three parts. First, we will review the typical pathological changes of AD and discuss microglia and astrocytes in terms of function and phenotypic changes. Second, we will describe microglia and astrocytes' physiological and pathological role in AD. These roles include the inflammatory response, "eat me" and "don't eat me" signals, Aβ seeding, propagation, clearance, synapse loss, synaptic pruning, remyelination, and demyelination. Last, we will review the pharmacological and non-pharmacological therapies targeting microglia and astrocytes in AD. We conclude that microglia and astrocytes are essential in the initiation and development of AD. Therefore, understanding the new role of microglia and astrocytes in AD progression is critical for future AD studies and clinical trials. Moreover, pharmacological, and non-pharmacological therapies targeting microglia and astrocytes, with specific studies investigating microglia and astrocyte-mediated neuronal damage and repair, may be a promising research direction for future studies regarding AD treatment and prevention.

Nanoligomers targeting NF-κB and NLRP3 reduce neuroinflammation and improve cognitive function with aging and tauopathy

Neuroinflammation contributes to impaired cognitive function in brain aging and neurodegenerative disorders like Alzheimer's disease, which is characterized by the aggregation of pathological tau. One major driver of both age- and tau-associated neuroinflammation is the NF-κB and NLRP3 signaling axis. However, current treatments targeting NF-κB or NLRP3 may have adverse/systemic effects, and most have not been clinically translatable. In this study, we tested the efficacy of a novel, nucleic acid therapeutic (Nanoligomer) cocktail specifically targeting both NF-κB and NLRP3 in the brain for reducing neuroinflammation and improving cognitive function in old (aged 19 months) wildtype mice, and in rTg4510 tau pathology mice (aged 2 months). We found that 4 weeks of NF-κB/NLRP3-targeting Nanoligomer treatment strongly reduced neuro-inflammatory cytokine profiles in the brain and improved cognitive-behavioral function in both old and rTg4510 mice. These effects of NF-κB/NLRP3-targeting Nanoligomers were also associated with reduced glial cell activation and pathology, favorable changes in transcriptome signatures of glia-associated inflammation (reduced) and neuronal health (increased), and positive systemic effects. Collectively, our results provide a basis for future translational studies targeting both NF-κB and NLRP3 in the brain, perhaps using Nanoligomers, to inhibit neuroinflammation and improve cognitive function with aging and neurodegeneration.

Porphyromonas gingivalis virulence factors induce toxic effects in SH-SY5Y neuroblastoma cells: GRK5 modulation as a protective strategy

Periodontitis (PDS) is a chronic inflammatory disease initiated by a dysbiosis of oral pathogenic bacterial species, such as Porphyromonas gingivalis (Pg). These bacteria can penetrate the bloodstream, releasing various endo and exotoxins that fuel the infection, and stimulate toxic inflammation in different compartments, including the brain. However, the specific mechanisms by which PDS/Pg contribute to brain disorders, such as Alzheimer's disease (AD), remain unclear. This study assessed the effects of Pg's virulence factors - lipopolysaccharide (LPS-Pg) and gingipains (gps) K (Kgp) and Rgp - on SH-SY5Y cells. Our results demonstrated that LPS-Pg activated signaling through the Toll-like receptor (TLR)-2/4 induced a significant downregulation of G protein-coupled receptor kinase 5 (GRK5). Additionally, LPS-Pg stimulation resulted in a robust increase in Tau phosphorylation (pTau) and p53 levels, while causing a marked reduction in Bcl2 and increased cell death compared to unstimulated cells (Ns). LPS-Pg also elevated inducible nitric oxide synthase (iNOS) expression, leading to oxidative damage. In cells overexpressing GRK5 via Adenovirus, LPS-Pg failed to increase iNOS and pTau levels compared to GFP control cells. High GRK5 levels also prevented the nuclear accumulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB). Furthermore, the overexpression of a GRK5 mutant form lacking the nuclear localization signal (ΔNLS) nearly abolished LPS-Pg induced p53 and iNOS upregulation. Finally, we tested whether Kgp and Rgp mediated similar effects and our data showed that both gps caused a marked downregulation of GRK5 leading to increased p53 and pTau levels. In conclusion, this study provides further insight into the toxic effects elicited by Pg in cells and suggests that preventing GRK5 deficiency may be a valid strategy to mitigate Pg-induced toxic effects (i.e. cell death, oxidative damage, and Tau hyperphosphorylation) in SH-SY5Y cells, which are typical molecular hallmarks of neurodegenerative disorders.

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

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

Myeloid ectopic viral integration site 2 accelerates the progression of Alzheimer's disease

Amyloid plaques, a major pathological hallmark of Alzheimer's disease (AD), are caused by an imbalance between the amyloidogenic and non-amyloidogenic pathways of amyloid precursor protein (APP). BACE1 cleavage of APP is the rate-limiting step for amyloid-β production and plaque formation in AD. Although the alteration of BACE1 expression in AD has been investigated, the underlying mechanisms remain unknown. In this study, we determined MEIS2 was notably elevated in AD models and AD patients. Alterations in the expression of MEIS2 can modulate the levels of BACE1. MEIS2 downregulation improved the learning and memory retention of AD mice and decreased the number of amyloid plaques. MEIS2 binds to the BACE1 promoter, positively regulates BACE1 expression, and accelerates APP amyloid degradation in vitro. Therefore, our findings suggest that MEIS2 might be a critical transcription factor in AD, since it regulates BACE1 expression and accelerates BACE1-mediated APP amyloidogenic cleavage. MEIS2 is a promising early intervention target for AD treatment.

Molecular mechanisms and therapeutic potential of lithium in Alzheimer's disease: repurposing an old class of drugs

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and memory loss. Despite advances in understanding the pathophysiological mechanisms of AD, effective treatments remain scarce. Lithium salts, recognized as mood stabilizers in bipolar disorder, have been extensively studied for their neuroprotective effects. Several studies indicate that lithium may be a disease-modifying agent in the treatment of AD. Lithium's neuroprotective properties in AD by acting on multiple neuropathological targets, such as reducing amyloid deposition and tau phosphorylation, enhancing autophagy, neurogenesis, and synaptic plasticity, regulating cholinergic and glucose metabolism, inhibiting neuroinflammation, oxidative stress, and apoptosis, while preserving mitochondrial function. Clinical trials have demonstrated that lithium therapy can improve cognitive function in patients with AD. In particular, meta-analyses have shown that lithium may be a more effective and safer treatment than the recently FDA-approved aducanumab for improving cognitive function in patients with AD. The affordability and therapeutic efficacy of lithium have prompted a reassessment of its use. However, the use of lithium may lead to potential side effects and safety issues, which may limit its clinical application. Currently, several new lithium formulations are undergoing clinical trials to improve safety and efficacy. This review focuses on lithium's mechanism of action in treating AD, highlighting the latest advances in preclinical studies and clinical trials. It also explores the side effects of lithium therapy and coping strategies, offering a potential therapeutic strategy for patients with AD.

From Lab Bench to Hope: Emerging Gene Therapies in Clinical Trials for Alzheimer's Disease

Alzheimer's disease is a progressive neurodegenerative disorder that affects memory and cognitive abilities, affecting millions of people around the world. Current treatments focus on the management of symptoms, as no effective therapy has been approved to modify the underlying disease process. Gene therapy is a promising approach that can offer disease-modifying treatment for AD, targeting various aspects of the pathophysiology of the disease. This review presents a comprehensive overview of the current state of gene therapy research for AD, with a specific focus on clinical trials and preclinical studies that have used nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), apolipoprotein E2 (APOE2), and human telomerase reverse transcriptase (hTERT) as therapeutic gene therapy approaches. These gene targets have shown potential to alleviate the neuropathology of AD in animal studies and have demonstrated feasibility and safety in non-human primates. Despite the failure of the NGF gene therapy approach in clinical trials, we have reviewed and highlighted the reported findings and evaluations from the trials. Furthermore, the review included the conclusions of postmortem brain tissue analysis of AD patients who received NGF gene therapy. The goal is to learn from the failed trials and improve the approach in the future. Although gene therapy shows promise, it faces several challenges and limitations, including optimizing gene delivery methods, enhancing safety and efficacy profiles, and determining long-term results. This review contributes to the growing body of literature on innovative treatments for AD and highlights the need for more research and development to advance gene therapy as a viable treatment option for AD.

The emerging role of brain neuroinflammatory responses in Alzheimer's disease

As the most common cause of dementia, Alzheimer's disease (AD) is characterized by neurodegeneration and synaptic loss with an increasing prevalence in the elderly. Increased inflammatory responses triggers brain cells to produce pro-inflammatory cytokines and accelerates the Aβ accumulation, tau protein hyper-phosphorylation leading to neurodegeneration. Therefore, in this paper, we discuss the current understanding of how inflammation affects brain activity to induce AD pathology, the inflammatory biomarkers and possible therapies that combat inflammation for AD.

Rationally Designed Peptoid Inhibitors of Amyloid-β Oligomerization

While plaques comprised of fibrillar Aβ aggregates are hallmarks of Alzheimer's disease, soluble Aβ oligomers present higher neurotoxicity. Thus, one therapeutic approach is to prevent the formation of Aβ oligomers and reduce their associated harmful effects. We have proposed a peptoid mimic of the Aβ hydrophobic KLVFF core as an ideal candidate aggregation inhibitor due to its ability to evade proteolytic degradation via repositioning of the side chain from the α-carbon to the amide nitrogen. This peptoid, JPT1, utilizes chiral sidechains to achieve a helical structure, while C-terminal addition of two phenylalanine residues places aromatic groups on two sides of the helix with spacing designed to facilitate interaction with amyloid β-sheet structure. We have previously shown that JPT1 modulates Aβ fibril formation. Here, we demonstrate that JPT1 also modulates Aβ oligomerization, and we explore the role of the charge on the linker between the KLVFF mimic and the extended aromatic residues. Additionally, we demonstrate that peptoid-induced changes in Aβ oligomerization correlate with attenuation of oligomer-induced nuclear factor-κB activation in SH-SY5Y human neuroblastoma cells. These findings support the therapeutic potential of peptoids to target early stages of Aβ aggregation and impact the associated Aβ-induced cellular response.

The reverse transcriptase inhibitor 3TC modulates hippocampal transcriptome signatures of inflammation in tauopathy model mice

Reducing neuroinflammation, a key contributor to brain aging and neurodegenerative diseases, is a promising strategy for improving cognitive function in these settings. The FDA-approved nucleoside reverse transcriptase inhibitor 3TC (Lamivudine) has been reported to improve cognitive function in old wild-type mice and multiple mouse models of neurodegenerative disease, but its effects on the brain have not been comprehensively investigated. In the current study, we used transcriptomics to broadly characterize the effects of long-term supplementation with a human-equivalent therapeutic dose of 3TC on the hippocampal transcriptome in male and female rTg4510 mice (a commonly studied model of tauopathy-associated neurodegeneration). We found that tauopathy increased hippocampal transcriptomic signatures of neuroinflammation/immune activation, but 3TC treatment reversed some of these effects. We also found that 3TC mitigated tauopathy-associated activation of key transcription factors that contribute to neuroinflammation and immune activation, and these changes were related to improved recognition memory performance. Collectively, our findings suggest that 3TC exerts protective effects against tauopathy in the hippocampus by modulating inflammation and immune activation, and they may provide helpful insight for ongoing clinical efforts to determine if 3TC and/or related therapeutics hold promise for treating neurodegeneration.

Gut Microbiota Metabolite Messengers in Brain Function and Pathology at a View of Cell Type-Based Receptor and Enzyme Reaction

The human gastrointestinal (GI) tract houses a diverse microbial community, known as the gut microbiome comprising bacteria, viruses, fungi, and protozoa. The gut microbiome plays a crucial role in maintaining the body's equilibrium and has recently been discovered to influence the functioning of the central nervous system (CNS). The communication between the nervous system and the GI tract occurs through a two-way network called the gut-brain axis. The nervous system and the GI tract can modulate each other through activated neuronal cells, the immune system, and metabolites produced by the gut microbiome. Extensive research both in preclinical and clinical realms, has highlighted the complex relationship between the gut and diseases associated with the CNS, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. This review aims to delineate receptor and target enzymes linked with gut microbiota metabolites and explore their specific roles within the brain, particularly their impact on CNS-related diseases.

Evaluating the Role of N-Acetyl-L-Tryptophan in the Aβ 1-42-Induced Neuroinflammation and Cognitive Decline in Alzheimer's Disease

Alzheimer's disease (AD), a neurodegenerative condition previously known to affect the older population, is also now seen in younger individuals. AD is often associated with cognitive decline and neuroinflammation elevation primarily due to amyloid β (Aβ) accumulation. Multiple pathological complications in AD call for therapies with a wide range of neuroprotection. Our study aims to evaluate the effect of N-acetyl-L-tryptophan (NAT) in ameliorating the cognitive decline and neuroinflammation induced by Aβ 1-42 oligomers and to determine the therapeutic concentration of NAT in the brain. We administered Aβ 1-42 oligomers in rats via intracerebroventricular (i.c.v.) injection to induce AD-like conditions. The NAT-treated animals lowered the cognitive decline in the Morris water maze characterized by shorter escape latency and increased path efficiency and platform entries. Interestingly, the hippocampus and frontal cortex showed downregulation of tumor necrosis factor, interleukin-6, and substance P levels. NAT treatment also reduced acetylcholinesterase activity and total and phosphorylated nuclear factor kappa B and Tau levels. Lastly, we observed upregulation of cAMP response element-binding protein 1 (CREB1) signaling. Surprisingly, our HPLC method was not sensitive enough to detect the therapeutic levels of NAT in the brain, possibly due to NAT concentrations being below the lowest limit of quantification of our validated method. To summarize, the administration of NAT significantly lowered cognitive decline, neuroinflammatory pathways, and Tau protein and triggered the upregulation of CREB1 signaling, suggesting its neuroprotective role in AD-like conditions.

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.

Dissecting the antidepressant effect of troxerutin: modulation of neuroinflammatory and oxidative stress biomarkers in lipopolysaccharide-treated mice

The role of neuroinflammation in the pathogenesis of depression has prompted the search for new antidepressants. Troxerutin, a bioflavonoid with anti-inflammatory and antioxidant properties, has shown promise, but its impact on neurobehavioral functions remains poorly understood. This study aimed to investigate the antidepressant potential of troxerutin and its effect on the neuroinflammatory response. Here, we exposed male Swiss mice (n = 5/group) to various treatments, including naive and negative controls receiving distilled water, troxerutin-treated groups administered at different doses (10, 20, 40 mg/kg, i.p.), and an imipramine-treated group (25 mg/kg, i.p.). After seven days of treatment, with the exception of the naive group, mice were administered a single dose of lipopolysaccharide (LPS, 0.83 mg/kg). Behavioral evaluations, consisting of the novelty-suppressed feeding (NSF) test, forced swim test (FST), and open field test (OFT), were conducted. Additionally, brain samples were collected for biochemical and immunohistochemical analyses. Troxerutin significantly reduced immobility time in the FST and mitigated behavioral deficits in the NSF test. Additionally, troxerutin increased glutathione (GSH) and superoxide dismutase (SOD) levels while reducing nitrite, malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interferon-gamma (IFN-γ) levels compared to the negative control. Immunohistochemistry analysis revealed decreased expression of inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-κB) in troxerutin-treated mice. Overall, these findings suggest that troxerutin exerts significant antidepressive-like effects, likely mediated by its anti-inflammatory and antioxidant mechanisms. The reduction in neuroinflammatory and oxidative stress biomarkers, along with the improvement in behavioral outcomes, underscores troxerutin's potential as a therapeutic agent for depression.

Reduced SH3RF3 may protect against Alzheimer's disease by lowering microglial pro-inflammatory responses via modulation of JNK and NFkB signaling

Understanding how high-risk individuals are protected from Alzheimer's disease (AD) may illuminate potential therapeutic targets. A previously identified non-coding SNP in SH3RF3/POSH2 significantly delayed disease onset in a Caribbean Hispanic cohort carrying the PSEN1 G206A mutation sufficient to cause early-onset AD and microglial expression of SH3RF3 has been reported to be a key driver of late-onset AD. SH3RF3 acts as a JNK pathway scaffold and can activate NFκB signaling. While effects of SH3RF3 knockdown in human neurons were subtle, including decreased phospho-tau S422, knockdown in human microglia significantly reduced inflammatory cytokines in response to either a viral mimic or oligomeric Aβ42. This was associated with reduced activation of JNK and NFκB pathways in response to these stimuli. Pharmacological inhibition of JNK or NFκB signaling phenocopied SH3RF3 knockdown. We also found PSEN1 G206A microglia have reduced inflammatory responses to oAβ42. Thus, further reduction of microglial inflammatory responses in PSEN1 mutant carriers by protective SNPs in SH3RF3 might reduce the link between amyloid and neuroinflammation to subsequently delay the onset of AD.

Catalpol reduced LPS induced BV2 immunoreactivity through NF-κB/NLRP3 pathways: an in Vitro and in silico study

Background: Ischemic Stroke (IS) stands as one of the primary cerebrovascular diseases profoundly linked with inflammation. In the context of neuroinflammation, an excessive activation of microglia has been observed. Consequently, regulating microglial activation emerges as a vital target for neuroinflammation treatment. Catalpol (CAT), a natural compound known for its anti-inflammatory properties, holds promise in this regard. However, its potential to modulate neuroinflammatory responses in the brain, especially on microglial cells, requires comprehensive exploration. Methods: In our study, we investigated into the potential anti-inflammatory effects of catalpol using lipopolysaccharide (LPS)-stimulated BV2 microglial cells as an experimental model. The production of nitric oxide (NO) by LPS-activated BV2 cells was quantified using the Griess reaction. Immunofluorescence was employed to measure glial cell activation markers. RT-qPCR was utilized to assess mRNA levels of various inflammatory markers. Western blot analysis examined protein expression in LPS-activated BV2 cells. NF-κB nuclear localization was detected by immunofluorescent staining. Additionally, molecular docking and molecular dynamics simulations (MDs) were conducted to explore the binding affinity of catalpol with key targets. Results: Catalpol effectively suppressed the production of nitric oxide (NO) induced by LPS and reduced the expression of microglial cell activation markers, including Iba-1. Furthermore, we observed that catalpol downregulated the mRNA expression of proinflammatory cytokines such as IL-6, TNF-α, and IL-1β, as well as key molecules involved in the NLRP3 inflammasome and NF-κB pathway, including NLRP3, NF-κB, caspase-1, and ASC. Our mechanistic investigations shed light on how catalpol operates against neuroinflammation. It was evident that catalpol significantly inhibited the phosphorylation of NF-κB and NLRP3 inflammasome activation, both of which serve as upstream regulators of the inflammatory cascade. Molecular docking and MDs showed strong binding interactions between catalpol and key targets such as NF-κB, NLRP3, and IL-1β. Conclusion: Our findings support the idea that catalpol holds the potential to alleviate neuroinflammation, and it is achieved by inhibiting the activation of NLRP3 inflammasome and NF-κB, ultimately leading to the downregulation of pro-inflammatory cytokines. Catalpol emerges as a promising candidate for the treatment of neuroinflammatory conditions.

Expression of SDF-1/CXCR4 and related inflammatory factors in sodium fluoride-treated hepatocytes

At present, the mechanism of fluorosis-induced damage to the hepatic system is unclear. Studies have shown that excess fluoride causes some degree of damage to the liver, including inflammation. The SDF-1/CXCR4 signaling axis has been reported to have an impact on the regulation of inflammation in human cells. In this study, we investigated the role of the SDF-1/CXCR4 signaling axis and related inflammatory factors in fluorosis through in vitro experiments on human hepatic astrocytes (LX-2) cultured with sodium fluoride. CCK-8 assays showed that the median lethal dose at 24 h was 2 mmol/l NaF, and these conditions were used for subsequent enzyme-linked immunosorbent assays (ELISAs) and quantitative real-time polymerase chain reaction (qPCR) analysis. The protein expression levels of SDF-1/CXCR4 and the related inflammatory factors nuclear factor-κB (NF-κB), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) were detected by ELISAs from the experimental and control groups. The mRNA expression levels of these inflammatory indicators were also determined by qPCR in both groups. Moreover, the expression levels of these factors were significantly higher in the experimental group than in the control group at both the protein and mRNA levels (P < 0.05). Excess fluorine may stimulate the SDF-1/CXCR4 signaling axis, activating the inflammatory NF-κB signaling pathway and increasing the expression levels of the related inflammatory factors IL-6, TNF-α and IL-1β. Identification of this mechanism is important for elucidating the pathogenesis of fluorosis-induced liver injury.

Emerging Therapeutic Potential of Fluoxetine on Cognitive Decline in Alzheimer's Disease: Systematic Review

Fluoxetine, a commonly prescribed medication for depression, has been studied in Alzheimer's disease (AD) patients for its effectiveness on cognitive symptoms. The aim of this systematic review is to investigate the therapeutic potential of fluoxetine in cognitive decline in AD, focusing on its anti-degenerative mechanisms of action and clinical implications. According to PRISMA, we searched MEDLINE, up to 1 April 2024, for animal and human studies examining the efficacy of fluoxetine with regard to the recovery of cognitive function in AD. Methodological quality was evaluated using the ARRIVE tool for animal AD studies and the Cochrane tool for clinical trials. In total, 22 studies were analyzed (19 animal AD studies and 3 clinical studies). Fluoxetine promoted neurogenesis and enhanced synaptic plasticity in preclinical models of AD, through a decrease in Aβ pathology and increase in BDNF, by activating diverse pathways (such as the DAF-16-mediated, TGF-beta1, ILK-AKT-GSK3beta, and CREB/p-CREB/BDNF). In addition, fluoxetine has anti-inflammatory properties/antioxidant effects via targeting antioxidant Nrf2/HO-1 and hindering TLR4/NLRP3 inflammasome. Only three clinical studies showed that fluoxetine ameliorated the cognitive performance of people with AD; however, several methodological issues limited the generalizability of these results. Overall, the high-quality preclinical evidence suggests that fluoxetine may have neuroprotective, antioxidant, and anti-inflammatory effects in AD animal models. While more high-quality clinical research is needed to fully understand the mechanisms underlying these effects, fluoxetine is a promising potential treatment for AD patients. If future clinical trials confirm its anti-degenerative and neuroprotective effects, fluoxetine could offer a new therapeutic approach for slowing down the progression of AD.

Rhein alleviates MPTP-induced Parkinson's disease by suppressing neuroinflammation via MAPK/IκB pathway

Background

Parkinson's disease (PD) is a common neurodegenerative disease with a rapid increase in incidence in recent years. Existing treatments cannot slow or stop the progression of PD. It was proposed that neuroinflammation leads to neuronal death, making targeting neuroinflammation a promising therapeutic strategy. Our previous studies have demonstrated that rhein protects neurons in vitro by inhibiting neuroinflammation, and it has been found to exhibit neuroprotective effects in Alzheimer's disease and epilepsy, but its neuroprotective mechanisms and effects on PD are still unclear.

Methods

PD animal model was induced by 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP). ELISA, RT-qPCR, western blot and Immunofluorescence were used to detect the levels of inflammatory cytokines and M1 polarization markers. The protein expression levels of signaling pathways were measured by western blot. Hematoxylin-eosin (HE) staining showed that rhein did not damage the liver and kidney. Two behavioral tests, pole test and rotarod test, were used to evaluate the improvement effect of rhein on movement disorders. The number of neurons in the substantia nigra was evaluated by Nissl staining. Immunohistochemistry and western blot were used to detect tyrosine hydroxylase (TH) and α-synuclein.

Results

Rhein inhibited the activation of MAPK/IκB signaling pathway and reduced the levels of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and M1 polarization markers of microglia in vivo. In a mouse model of PD, rhein ameliorated movement disorders, reduced dopaminergic neuron damage and α-synuclein deposition.

Conclusion

Rhein inhibits neuroinflammation through MAPK/IκB signaling pathway, thereby reducing neurodegeneration, α-synuclein deposition, and improving movement disorders in Parkinson's disease.

Altered glia-neuron communication in Alzheimer's Disease affects WNT, p53, and NFkB Signaling determined by snRNA-seq

BACKGROUND

Alzheimer's disease is the most common cause of dementia and is characterized by amyloid-β plaques, tau neurofibrillary tangles, and neuronal loss. Although neuronal loss is a primary hallmark of Alzheimer's disease, it is known that non-neuronal cell populations are ultimately responsible for maintaining brain homeostasis and neuronal health through neuron-glia and glial cell crosstalk. Many signaling pathways have been proposed to be dysregulated in Alzheimer's disease, including WNT, TGFβ, p53, mTOR, NFkB, and Pi3k/Akt signaling. Here, we predict altered cell-cell communication between glia and neurons.

METHODS

Using public snRNA-sequencing data generated from postmortem human prefrontal cortex, we predicted altered cell-cell communication between glia (astrocytes, microglia, oligodendrocytes, and oligodendrocyte progenitor cells) and neurons (excitatory and inhibitory). We confirmed interactions in a second and third independent orthogonal dataset. We determined cell-type-specificity using Jaccard Similarity Index and investigated the downstream effects of altered interactions in inhibitory neurons through gene expression and transcription factor activity analyses of signaling mediators. Finally, we determined changes in pathway activity in inhibitory neurons.

RESULTS

Cell-cell communication between glia and neurons is altered in Alzheimer's disease in a cell-type-specific manner. As expected, ligands are more cell-type-specific than receptors and targets. We identified ligand-receptor pairs in three independent datasets and found involvement of the Alzheimer's disease risk genes APP and APOE across datasets. Most of the signaling mediators of these interactions were not significantly differentially expressed, however, the mediators that are also transcription factors had differential activity between AD and control. Namely, MYC and TP53, which are associated with WNT and p53 signaling, respectively, had decreased TF activity in Alzheimer's disease, along with decreased WNT and p53 pathway activity in inhibitory neurons. Additionally, inhibitory neurons had both increased NFkB signaling pathway activity and increased TF activity of NFIL3, an NFkB signaling-associated transcription factor.

CONCLUSIONS

Cell-cell communication between glia and neurons in Alzheimer's disease is altered in a cell-type-specific manner involving Alzheimer's disease risk genes. Signaling mediators had altered transcription factor activity suggesting altered glia-neuron interactions may dysregulate signaling pathways including WNT, p53, and NFkB in inhibitory neurons.

Nanoligomers targeting NF-κB and NLRP3 reduce neuroinflammation and improve cognitive function with aging and tauopathy

Neuroinflammation contributes to impaired cognitive function in brain aging and neurodegenerative disorders like Alzheimer's disease, which is characterized by the aggregation of pathological tau. One major driver of both age- and tau-associated neuroinflammation is the NF-κB and NLRP3 signaling axis. However, current treatments targeting NF-κB or NLRP3 may have adverse/systemic effects, and most have not been clinically translatable. In this study, we tested the efficacy of a novel, nucleic acid therapeutic (Nanoligomer) cocktail specifically targeting both NF-κB and NLRP3 in the brain for reducing neuroinflammation and improving cognitive function in old (aged 19 months) wildtype mice, and in rTg4510 tau pathology mice (aged 2 months). We found that 4 weeks of NF-κB/NLRP3-targeting Nanoligomer treatment strongly reduced neuro-inflammatory cytokine profiles in the brain and improved cognitive-behavioral function in both old and rTg4510 mice. These effects of NF-κB/NLRP3-targeting Nanoligomers were also associated with reduced glial cell activation and pathology, favorable changes in transcriptome signatures of glia-associated inflammation (reduced) and neuronal health (increased), and positive systemic effects. Collectively, our results provide a basis for future translational studies targeting both NF-κB and NLRP3 in the brain, perhaps using Nanoligomers, to inhibit neuroinflammation and improve cognitive function with aging and neurodegeneration.

Connecting GSK-3β Inhibitory Activity with IKK-β or ROCK-1 Inhibition to Target Tau Aggregation and Neuroinflammation in Alzheimer's Disease-Discovery, In Vitro and In Cellulo Activity of Thiazole-Based Inhibitors

GSK-3β, IKK-β, and ROCK-1 kinases are implicated in the pathomechanism of Alzheimer's disease due to their involvement in the misfolding and accumulation of amyloid β (Aβ) and tau proteins, as well as inflammatory processes. Among these kinases, GSK-3β plays the most crucial role. In this study, we present compound 62, a novel, remarkably potent, competitive GSK-3β inhibitor (IC50 = 8 nM, Ki = 2 nM) that also exhibits additional ROCK-1 inhibitory activity (IC50 = 2.3 µM) and demonstrates anti-inflammatory and neuroprotective properties. Compound 62 effectively suppresses the production of nitric oxide (NO) and pro-inflammatory cytokines in the lipopolysaccharide-induced model of inflammation in the microglial BV-2 cell line. Furthermore, it shows neuroprotective effects in an okadaic-acid-induced tau hyperphosphorylation cell model of neurodegeneration. The compound also demonstrates the potential for further development, characterized by its chemical and metabolic stability in mouse microsomes and fair solubility.

Biological role of mitochondrial TLR4-mediated NF-κB signaling pathway in central nervous system injury

Previous studies suggested that central nervous system injury is often accompanied by the activation of Toll-like receptor 4/NF-κB pathway, which leads to the upregulation of proapoptotic gene expression, causes mitochondrial oxidative stress, and further aggravates the inflammatory response to induce cell apoptosis. Subsequent studies have shown that NF-κB and IκBα can directly act on mitochondria. Therefore, elucidation of the specific mechanisms of NF-κB and IκBα in mitochondria may help to discover new therapeutic targets for central nervous system injury. Recent studies have suggested that NF-κB (especially RelA) in mitochondria can inhibit mitochondrial respiration or DNA expression, leading to mitochondrial dysfunction. IκBα silencing will cause reactive oxygen species storm and initiate the mitochondrial apoptosis pathway. Other research results suggest that RelA can regulate mitochondrial respiration and energy metabolism balance by interacting with p53 and STAT3, thus initiating the mitochondrial protection mechanism. IκBα can also inhibit apoptosis in mitochondria by interacting with VDAC1 and other molecules. Regulating the biological role of NF-κB signaling pathway in mitochondria by targeting key proteins such as p53, STAT3, and VDAC1 may help maintain the balance of mitochondrial respiration and energy metabolism, thereby protecting nerve cells and reducing inflammatory storms and death caused by ischemia and hypoxia.

Targeting NF-κB in Hepatic Ischemia-Reperfusion Alleviation: from Signaling Networks to Therapeutic Targeting

Hepatic ischemia-reperfusion injury (HIRI) is a major complication of liver trauma, resection, and transplantation that can lead to liver dysfunction and failure. Scholars have proposed a variety of liver protection methods aimed at reducing ischemia-reperfusion damage, but there is still a lack of effective treatment methods, which urgently needs to find new effective treatment methods for patients. Many studies have reported that signaling pathway plays a key role in HIRI pathological process and liver function recovery mechanism, among which nuclear transfer factor-κB (NF-κB) signaling pathway is one of the signal transduction closely related to disease. NF-κB pathway is closely related to HIRI pathologic process, and inhibition of this pathway can delay oxidative stress, inflammatory response, cell death, and mitochondrial dysfunction. In addition, NF-κB can also interact with PI3K/Akt, MAPK, and Nrf2 signaling pathways to participate in HIRI regulation. Based on the role of NF-κB pathway in HIRI, it may be a potential target pathway for HIRI. This review emphasizes the role of inhibiting the NF-κB signaling pathway in oxidative stress, inflammatory response, cell death, and mitochondrial dysfunction in HIRI, as well as the effects of related drugs or inhibitors targeting NF-κB on HIRI. The objective of this review is to elucidate the role and mechanism of NF-κB pathway in HIRI, emphasize the important role of NF-κB pathway in the prevention and treatment of HIRI, and provide a theoretical basis for the target NF-κB pathway as a therapy for HIRI.

Flower Power: An Overview on Chemistry and Biological Impact of Selected Essential Oils from Blossoms

Natural raw materials such as essential oils have received more and more attention in recent decades, whether in the food industry, as flavorings and preservatives, or as insecticides and insect repellents. They are, furthermore, very popular as fragrances in perfumes, cosmetics, and household products. In addition, aromatherapy is widely used to complement conventional medicine. This review summarizes investigations on the chemical composition and the most important biological impacts of essential oils and volatile compounds extracted from selected aromatic blossoms, including Lavandula angustifolia, Matricaria recutita, Rosa x damascena, Jasminum grandiflorum, Citrus x aurantium, Cananga odorata, and Michelia alba. The literature was collected from PubMed, Google Scholar, and Science Direct. Blossom essential oils discussed in this work are used in a wide variety of clinical issues. The application is consistently described as safe in studies and meta-analyses, although there are notes that using essential oils can also have side effects, especially dermatologically. However, it can be considered as confirmed that essential oils have positive influences on humans and can improve quality of life in patients with psychiatric disorders, critically ill patients, and patients in other exceptional situations. Although the positive effect of essential oils from blossoms has repeatedly been reported, evidence-based clinical investigations are still underrepresented, and the need for research is demanded.

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.

Evaluation of altered cell-cell communication between glia and neurons in the hippocampus of 3xTg-AD mice at two time points

Alzheimer's disease (AD) is the most common form of dementia and is characterized by progressive memory loss and cognitive decline, affecting behavior, speech, and motor abilities. The neuropathology of AD includes the formation of extracellular amyloid-β plaque and intracellular neurofibrillary tangles of phosphorylated tau, along with neuronal loss. While neuronal loss is an AD hallmark, cell-cell communication between neuronal and non-neuronal cell populations maintains neuronal health and brain homeostasis. To study changes in cell-cell communication during disease progression, we performed snRNA-sequencing of the hippocampus from female 3xTg-AD and wild-type littermates at 6 and 12 months. We inferred differential cell-cell communication between 3xTg-AD and wild-type mice across time points and between senders (astrocytes, microglia, oligodendrocytes, and OPCs) and receivers (excitatory and inhibitory neurons) of interest. We also assessed the downstream effects of altered glia-neuron communication using pseudobulk differential gene expression, functional enrichment, and gene regulatory analyses. We found that glia-neuron communication is increasingly dysregulated in 12-month 3xTg-AD mice. We also identified 23 AD-associated ligand-receptor pairs that are upregulated in the 12-month-old 3xTg-AD hippocampus. Our results suggest increased AD association of interactions originating from microglia. Signaling mediators were not significantly differentially expressed but showed altered gene regulation and TF activity. Our findings indicate that altered glia-neuron communication is increasingly dysregulated and affects the gene regulatory mechanisms in neurons of 12-month-old 3xTg-AD mice.

Frequency and duration of sensory flicker controls astrocyte and neuron specific transcriptional profiles in 5xFAD mice

Background

Current clinical trials are investigating gamma frequency sensory stimulation as a potential therapeutic strategy for Alzheimer's disease, yet we lack a comprehensive picture of the effects of this stimulation on multiple aspects of brain function. While most prior research has focused on gamma frequency sensory stimulation, we previously showed that exposing mice to visual flickering stimulation increased MAPK and NFκB signaling in the visual cortex in a manner dependent on duration and frequency of sensory stimulation exposure. Because these pathways control multiple neuronal and glial functions and are differentially activated based on the duration and frequency of flicker stimulation, we aimed to define the transcriptional effects of different frequencies and durations of flicker stimulation on multiple brain functions.

Methods

We exposed 5xFAD mice to different frequencies of audio/visual flicker stimulation (constant light, 10Hz, 20Hz, 40Hz) for durations of 0.5hr, 1hr, or 4hr, then used bulk RNAseq to profile transcriptional changes within the visual cortex and hippocampus tissues. Using weighted gene co-expression network analysis, we identified modules of co-expressed genes controlled by frequency and/or duration of stimulation.

Results

Within the visual cortex, we found that all stimulation frequencies caused fast activation of a module of immune genes within 1hr and slower suppression of synaptic genes after 4hrs of stimulation. Interestingly, all frequencies of stimulation led to slow suppression of astrocyte specific gene sets, while activation of neuronal gene sets was frequency and duration specific. In contrast, in the hippocampus, immune and synaptic modules were suppressed based on the frequency of stimulation. Specifically,10Hz activated a module of genes associated with mitochondrial function, metabolism, and synaptic translation while 10Hz rapidly suppressed a module of genes linked to neurotransmitter activity.

Conclusion

Collectively, our data indicate that the frequency and duration of flicker stimulation controls immune, neuronal, and metabolic genes in multiple regions of the brain affected by Alzheimer's disease. Flicker stimulation may thus represent a potential therapeutic strategy that can be tuned based on the brain region and the specific cellular process to be modulated.

NF-ĸB axis in diabetic neuropathy, cardiomyopathy and nephropathy: A roadmap from molecular intervention to therapeutic strategies

Diabetes mellitus (DM) is a metabolic illness defined by elevated blood glucose levels, mediating various tissue alterations, including the dysfunction of vital organs. Diabetes mellitus (DM) can lead to many consequences that specifically affect the brain, heart, and kidneys. These issues are known as neuropathy, cardiomyopathy, and nephropathy, respectively. Inflammation is acknowledged as a pivotal biological mechanism that contributes to the development of various diabetes consequences. NF-κB modulates inflammation and the immune system at the cellular level. Its abnormal regulation has been identified in several clinical situations, including cancer, inflammatory bowel illnesses, cardiovascular diseases, and Diabetes Mellitus (DM). The purpose of this review is to evaluate the potential impact of NF-κB on complications associated with DM. Enhanced NF-κB activity promotes inflammation, resulting in cellular harm and compromised organ performance. Phytochemicals, which are therapeutic molecules, can potentially decline the NF-κB level, therefore alleviating inflammation and the progression of problems correlated with DM. More importantly, the regulation of NF-κB can be influenced by various factors, such as TLR4 in DM. Highlighting these factors can facilitate the development of novel therapies in the future.

Altered Glia-Neuron Communication in Alzheimer's Disease Affects WNT, p53, and NFkB Signaling Determined by snRNA-seq

Background

Alzheimer's disease is the most common cause of dementia and is characterized by amyloid-β plaques, tau neurofibrillary tangles, and neuronal loss. Although neuronal loss is a primary hallmark of Alzheimer's disease, it is known that non-neuronal cell populations are ultimately responsible for maintaining brain homeostasis and neuronal health through neuron-glia and glial cell crosstalk. Many signaling pathways have been proposed to be dysregulated in Alzheimer's disease, including WNT, TGFβ, p53, mTOR, NFkB, and Pi3k/Akt signaling. Here, we predict altered cell-cell communication between glia and neurons.

Methods

Using public snRNA-sequencing data generated from postmortem human prefrontal cortex, we predicted altered cell-cell communication between glia (astrocytes, microglia, oligodendrocytes, and oligodendrocyte progenitor cells) and neurons (excitatory and inhibitory). We confirmed interactions in a second and third independent orthogonal dataset. We determined cell-type-specificity using Jaccard Similarity Index and investigated the downstream effects of altered interactions in inhibitory neurons through gene expression and transcription factor activity analyses of signaling mediators. Finally, we determined changes in pathway activity in inhibitory neurons.

Results

Cell-cell communication between glia and neurons is altered in Alzheimer's disease in a cell-type-specific manner. As expected, ligands are more cell-type-specific than receptors and targets. We identified ligand-receptor pairs in three independent datasets and found involvement of the Alzheimer's disease risk genes APP and APOE across datasets. Most of the signaling mediators of these interactions were not differentially expressed, however, the mediators that are also transcription factors had differential activity between AD and control. Namely, MYC and TP53, which are associated with WNT and p53 signaling, respectively, had decreased TF activity in Alzheimer's disease, along with decreased WNT and p53 pathway activity in inhibitory neurons. Additionally, inhibitory neurons had both increased NFkB signaling pathway activity and increased TF activity of NFIL3, an NFkB signaling-associated transcription factor.

Conclusions

Cell-cell communication between glia and neurons in Alzheimer's disease is altered in a cell-type-specific manner involving Alzheimer's disease risk genes. Signaling mediators had altered transcription factor activity suggesting altered glia-neuron interactions may dysregulate signaling pathways including WNT, p53, and NFkB in inhibitory neurons.

Unraveling the genetic architecture of blood unfolded p-53 among non-demented elderlies: novel candidate genes for early Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a heritable neurodegenerative disease whose long asymptomatic phase makes the early diagnosis of it pivotal. Blood U-p53 has recently emerged as a superior predictive biomarker for AD in the early stages. We hypothesized that genetic variants associated with blood U-p53 could reveal novel loci and pathways involved in the early stages of AD.

RESULTS

We performed a blood U-p53 Genome-wide association study (GWAS) on 484 healthy and mild cognitively impaired subjects from the ADNI cohort using 612,843 Single nucleotide polymorphisms (SNPs). We performed a pathway analysis and prioritized candidate genes using an AD single-cell gene program. We fine-mapped the intergenic SNPs by leveraging a cell-type-specific enhancer-to-gene linking strategy using a brain single-cell multimodal dataset. We validated the candidate genes in an independent brain single-cell RNA-seq and the ADNI blood transcriptome datasets. The rs279686 between AASS and FEZF1 genes was the most significant SNP (p-value = 4.82 × 10-7). Suggestive pathways were related to the immune and nervous systems. Twenty-three candidate genes were prioritized at 27 suggestive loci. Fine-mapping of 5 intergenic loci yielded nine cell-specific candidate genes. Finally, 15 genes were validated in the independent single-cell RNA-seq dataset, and five were validated in the ADNI blood transcriptome dataset.

CONCLUSIONS

We underlined the importance of performing a GWAS on an early-stage biomarker of AD and leveraging functional omics datasets for pinpointing causal genes in AD. Our study prioritized nine genes (SORCS1, KIF5C, TMEFF2, TMEM63C, HLA-E, ATAT1, TUBB, ARID1B, and RUNX1) strongly implicated in the early stages of AD.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Effect of astrocyte GPER on the optic nerve inflammatory response following optic nerve injury in mice

Activated astrocytes are a primary source of inflammatory factors following traumatic optic neuropathy (TON). Accumulation of inflammatory factors in this context leads to increased axonal damage and loss of retinal ganglion cells (RGCs). Therefore, in the present study, we explored the role of the astrocyte G protein-coupled estrogen receptor (GPER) in regulating inflammatory factors following optic nerve crush (ONC), and analyzed its potential regulatory mechanisms. Overall, our results showed that GPER was abundantly expressed in the optic nerve, and co-localized with glial fibrillary acidic proteins (GFAP). Exogenous administration of G-1 led to a significant reduction in astrocyte activation and expression of inflammation-related factors (including IL-1β, TNF-α, NFκB, and p-NFκB). Additionally, it dramatically increased the survival of RGCs. In contrast, astrocytes were activated to a greater extent by exogenous G15 administration; however, RGCs survival was significantly reduced. In vitro, GPER activation significantly reduced astrocyte activation and the release of inflammation-related factors. In conclusion, activation of astrocyte GPER significantly reduced ONC inflammation levels, and should be explored as a potential target pathway for protecting the optic nerve and RGCs after TON.

Impaired 26S proteasome causes learning and memory deficiency and induces neuroinflammation mediated by NF-κB in mice

A reduction in proteasome activity, loss of synapses and increased neuroinflammation in the brain are hallmarks of aging and many neurodegenerative disorders, including Alzheimer's disease (AD); however, whether proteasome dysfunction is causative to neuroinflammation remains less understood. In this study, we investigated the impact of 26S proteasome deficiency on neuroinflammation in the Psmc1 knockout (KO) mice deficient in a 19S proteasome subunit limited to the forebrain region. Our results revealed that impaired 26S proteasome led to reduced learning and memory capability and overt neuroinflammation in the synapses of the Psmc1 KO brain at eight weeks of age. Moreover, pronounced neuroinflammation was also found in the whole brain cortex, which was confirmed by increased levels of several key immune response-related proteins, including Stat1, Trem2 and NF-κB, and by activation of astrocytes and microglia in the KO brain. To validate NF-κB mediating neuroinflammation, we administered a selective NF-κB inhibitor to the KO animals at 5 weeks of age for three weeks, and then, animal behaviors and neuroinflammation were assessed when they reached eight weeks of age. Following the treatment, the KO mice exhibited improved behaviors and reduced neuroinflammation compared to the control animals. These data indicate that impaired 26S proteasome causes AD-like cognitive deficiency and induces neuroinflammation mediated largely by NF-κB. These results may aid development of effective therapeutics and better understanding of the pathogenesis of AD and many other neurodegenerative disorders where impaired proteasome is consistently coupled with neuroinflammation.

Immediate-Early Genes as Influencers in Genetic Networks and their Role in Alzheimer's Disease

Immediate-early genes (IEGs) are a class of activity-regulated genes (ARGs) that are transiently and rapidly activated in the absence of de novo protein synthesis in response to neuronal activity. We explored the role of IEGs in genetic networks to pinpoint potential drug targets for Alzheimer's disease (AD). Using a combination of network analysis and genome-wide association study (GWAS) summary statistics we show that (1) IEGs exert greater topological influence across different human and mouse gene networks compared to other ARGs, (2) ARGs are sparsely involved in diseases and significantly more mutational constrained compared to non-ARGs, (3) Many AD-linked variants are in ARGs gene regions, mainly in MARK4 near FOSB, with an AD risk eQTL that increases MARK4 expression in cortical areas, (4) MARK4 holds an influential place in a dense AD multi-omic network and a high AD druggability score. Our work on IEGs' influential network role is a valuable contribution to guiding interventions for diseases marked by dysregulation of their downstream targets and highlights MARK4 as a promising underexplored AD-target.

An EWAS of dementia biomarkers and their associations with age, African ancestry, and PTSD

BACKGROUND

Large-scale cohort and epidemiological studies suggest that PTSD confers risk for dementia in later life but the biological mechanisms underlying this association remain unknown. This study examined this question by assessing the influences of PTSD, APOE ε4 genotypes, DNA methylation, and other variables on the age- and dementia-associated biomarkers Aβ40, Aβ42, GFAP, NfL, and pTau-181 measured in plasma. Our primary hypothesis was that PTSD would be associated with elevated levels of these markers.

METHODS

Analyses were based on data from a PTSD-enriched cohort of 849 individuals. We began by performing factor analyses of the biomarkers, the results of which identified a two-factor solution. Drawing from the ATN research framework, we termed the first factor, defined by Aβ40 and Aβ42, "Factor A" and the second factor, defined by GFAP, NfL and pTau-181, "Factor TN." Next, we performed epigenome-wide association analyses (EWAS) of the two-factor scores. Finally, using structural equation modeling (SEM), we evaluated (a) the influence of PTSD, age, APOE ε4 genotype and other covariates on levels of the ATN factors, and (b) tested the mediating influence of the EWAS-significant DNAm loci on these associations.

RESULTS

The Factor A EWAS identified one significant locus, cg13053408, in FANCD2OS. The Factor TN analysis identified 3 EWAS-significant associations: cg26033520 near ASCC1, cg23156469 in FAM20B, and cg15356923 in FAM19A4. The SEM showed age to be related to both factors, more so with Factor TN (β = 0.581, p < 0.001) than Factor A (β = 0.330, p < 0.001). Genotype-determined African ancestry was associated with lower Factor A (β = 0.196, p < 0.001). Contrary to our primary hypothesis, we found a modest negative bivariate correlation between PTSD and the TN factor scores (r = - 0.133, p < 0.001) attributable primarily to reduced levels of GFAP (r = - 0.128, p < 0.001).

CONCLUSIONS

This study identified novel epigenetic associations with ATN biomarkers and demonstrated robust age and ancestral associations that will be essential to consider in future efforts to develop the clinical applications of these tests. The association between PTSD and reduced GFAP, which has been reported previously, warrants further investigation.

Chemical components and against alzheimer's disease effects of the calyxes of Physalis alkekengi L. var. franchetii (Mast.) Makino

Physalis alkekengi L. var. franchetii (Mast.) Makino (PA), a traditional Chinese medicine, is utilised for treating dermatitis, sore throat, dysuria, and cough. This research aimed to identify the main constituents in the four extracted portions from the calyces of PA (PAC) utilising ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The Alzheimer's disease (AD) mice model was induced by D-galactose (D-gal) combined with aluminium chloride (AlCl3). Subsequent investigation into the underlying mechanisms involved behavioural and histopathological observations. The results demonstrated that four extracted portions of PAC (PACE) significantly enhanced memory and learning abilities in the Morris water maze. The concentrations of Aβ, tau and p-tau in brain tissue exhibited a significant decrease relative to the model group. Moreover, the four PACE treatment groups increased the glutathione (GSH) and superoxide dismutase (SOD) levels, while concurrently reducing malondialdehyde (MDA), interleukin-1β (IL-1β) and interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) levels. In summary, the current study demonstrates that the four PACE formulations exhibit beneficial anti-AD properties, with the most pronounced efficacy observed in the EA group. Additionally, PAC shows potential in mitigating neuroinflammation and oxidative damage by inhibiting the TLR4/NF-κB signalling pathway. This research lays a theoretical groundwork for the future clinical development and utilisation of PAC in treating AD.

A New Strategy for the Regulation of Neuroinflammation: Exosomes Derived from Mesenchymal Stem Cells

Neuroinflammation is an important pathogenesis of neurological diseases and causes a series of physiopathological changes, such as abnormal activation of glial cells, neuronal degeneration and death, and disruption of the blood‒brain barrier. Therefore, modulating inflammation may be an important therapeutic tool for treating neurological diseases. Mesenchymal stem cells (MSCs), as pluripotent stem cells, have great therapeutic potential for neurological diseases due to their regenerative ability, immunity, and ability to regulate inflammation. However, recent studies have shown that MSC-derived exosomes (MSC-Exos) play a major role in this process and play a key role in neuroprotection by regulating neuroglia. This review summarizes the recent progress made in regulating neuroinflammation by focusing on the mechanisms by which MSC-Exos are involved in the regulation of glial cells through signaling pathways such as the TLR, NF-κB, MAPK, STAT, and NLRP3 pathways to provide some references for subsequent research and therapy.

Novel quinazolinone Derivatives: Design, synthesis and in vivo evaluation as potential agents targeting Alzheimer disease

Since Alzheimer disease is one of the most prevalent types of dementia with a high mortality and disability rate, so development of multi-target drugs becomes the major strategy for battling AD. This study shows the development of a series of quinazolinone based derivatives as novel, multifunctional anti-AD drugs that exhibit both cholinesterase inhibitoryand anti-inflammatory properties. The preliminary results of the in vitro AChE inhibition activity showed that compounds 4b, 5a, 6f, 6h and 7b were better represented for further evaluation. Furthermore, in-vivo AChE inhibition activity and behavior Morris water maze test against donepezil as reference drug were evaluated. Additionally, hippocampal inflammatory markers; TNF-α, NFĸB, IL-1β and IL-6 and antioxidant markers; SOD and MDA were assessed to evaluate the efficacy of quinazolinone derivatives against AD hallmarks. The results showed that 6f, 6h and 7b have promising anti-acetylcholinesterase, anti-inflammatory and antioxidant activities thus, have a significant effect in treatment of AD. Moreover, Histopathological examination revealed that 6f, 6h and 7b derivatives have neuroprotective effect against neuronal damage caused by induced scopolamine model in mice. Finally, the binding ability of the synthesized derivatives to the target, AChE was investigated through molecular docking which reflected significant interactions to the target based on their docking binding scores. Hence, the newly designed quinazolinone derivatives possess promising anti-acetylcholinesterase activity and challenging for the management of AD in the future.

Sinomenine regulates the cholinergic anti-inflammatory pathway to inhibit TLR4/NF-κB pathway and protect the homeostasis in brain and gut in scopolamine-induced Alzheimer's disease mice

Sinomenine (SIN), an alkaloid extracted from the Chinese herbal medicine Sinomenium acutum, has great potential in anti-inflammatory, immune regulation, analgesic and sedative, and is already a clinical drug for the treatment of rheumatoid arthritis in China. Our previous studies show SIN inhibits inflammation by regulating ɑ7nAChR, a key receptor of cholinergic anti-inflammatory pathway (CAP), which plays an important role in regulating peripheral and central nervous system inflammation. Growing evidence supports the cholinergic dysregulation and inflammatory responses play the key role in the pathogenesis of AD. The intervention effects of SIN on AD by regulating CAP and homeostasis in brain and gut were analyzed for the first time in the present study using scopolamine-induced AD model mice. Behavioral tests were used to assess the cognitive performance. The neurons loss, cholinergic function, inflammation responses, biological barrier function in the mouse brain and intestinal tissues were evaluated through a variety of techniques, and the gut microbiota was detected using 16SrRNA sequencing. The results showed that SIN significantly inhibited the cognitive decline, dysregulation of cholinergic system, peripheral and central inflammation, biological barrier damage as well as intestinal flora disturbance caused by SCOP in mice. More importantly, SIN effectively regulated CAP to suppress the activation of TLR4/NF-κB and protect the homeostasis in brain and gut to alleviate cognitive impairment.

Qinzhizhudan formula dampens inflammation in microglia polarization of vascular dementia rats by blocking MyD88/NF-κB signaling pathway: Through integrating network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Qinzhizhudan Formula (QZZD) is composed of Scutellaria baicalensis Georgi (Huang Qin) extract, Gardenia jasminoides (Zhizi) extract and Suis Fellis Pulvis (Zhudanfen) (ratio of 4:5:6). This formula is optimized from Qingkailing (QKL) injection. Regarding brain injury, QZZD is protective. However, the mechanism by which QZZD treats vascular dementia (VD) has not been elucidated.

AIM OF THE STUDY

To ascertain QZZD's effect on the treatment of VD and further investigate the molecular mechanisms.

MATERIALS AND METHODS

In this study, we screened the possible components and targets of QZZD against VD and microglia polarization using network pharmacology (NP), then an animal model of bilateral common carotid artery ligation method (2VO) was induced. Afterward, The Morris water maze was employed to evaluate cognitive ability, and pathological alterations in the CA1 area of the hippocampus were detected using HE and Nissl staining. To confirm the affect of QZZD on VD and its molecular mechanism, the contents of inflammatory factors IL-1β, TNF-α, IL-4, and IL-10 were performed to detect by ELISA, the phenotype polarization of microglia cells was detected by immunofluorescence staining, and the expressions of MyD88, p-IκBα and p-NF-κB p65 in brain tissue were detected by western blot.

RESULTS

A total of 112 active compounds and 363 common targets of QZZD, microglia polarization, and VD were identified, according to the NP analysis. 38 hub targets were screened out from the PPI network. GO analysis and KEGG pathway analysis showed that QZZD may regulate microglia polarization through anti-inflammatory mechanism such as Toll-like receptor signaling pathway and NF-κB signaling pathway. The further results showed that QZZD can alleviate the memory impairment induced by 2VO. QZZD profoundly rescued brain hippocampus neuronal damage and increased the number of neurons. These advantageous outcomes were linked to the control of microglia polarization. QZZD decreased M1 phenotypic marker expression while increasing M2 phenotypic marker expression. QZZD may controll the polarization of the M1 microglia by blocking the core part of Toll-like receptor signaling pathway, that is the MyD88/NF-κB signaling pathway, which reduced the neurotoxic effects of the microglia.

CONCLUSION

Here, we explored the anti-VD microglial polarization characteristic of QZZD for the first time and clarified its mechanisms. These findings will provide valuable clues for the discovery of anti-VD agents.

Nanotechnology for microglial targeting and inhibition of neuroinflammation underlying Alzheimer's pathology

BACKGROUND

Alzheimer's disease (AD) is considered to have a multifactorial etiology. The hallmark of AD is progressive neurodegeneration, which is characterized by the deepening loss of memory and a high mortality rate in the elderly. The neurodegeneration in AD is believed to be exacerbated following the intercoupled cascades of extracellular amyloid beta (Aβ) plaques, uncontrolled microglial activation, and neuroinflammation. Current therapies for AD are mostly designed to target the symptoms, with limited ability to address the mechanistic triggers for the disease. In this study, we report a novel nanotechnology based on microglial scavenger receptor (SR)-targeting amphiphilic nanoparticles (NPs) for the convergent alleviation of fibril Aβ (fAβ) burden, microglial modulation, and neuroprotection.

METHODS

We designed a nanotechnology approach to regulate the SR-mediated intracellular fAβ trafficking within microglia. We synthesized SR-targeting sugar-based amphiphilic macromolecules (AM) and used them as a bioactive shell to fabricate serum-stable AM-NPs via flash nanoprecipitation. Using electron microscopy, in vitro approaches, ELISA, and confocal microscopy, we investigated the effect of AM-NPs on Aβ fibrilization, fAβ-mediated microglial inflammation, and neurotoxicity in BV2 microglia and SH-SY5Y neuroblastoma cell lines.

RESULTS

AM-NPs interrupted Aβ fibrilization, attenuated fAβ microglial internalization via targeting the fAβ-specific SRs, arrested the fAβ-mediated microglial activation and pro-inflammatory response, and accelerated lysosomal degradation of intracellular fAβ. Moreover, AM-NPs counteracted the microglial-mediated neurotoxicity after exposure to fAβ.

CONCLUSIONS

The AM-NP nanotechnology presents a multifactorial strategy to target pathological Aβ aggregation and arrest the fAβ-mediated pathological progression in microglia and neurons.