Microglia, neuroinflammation, and beta-amyloid protein in Alzheimer's disease

Neurobiological role and therapeutic potential of exercise-induced irisin in Alzheimer's disease management

Alzheimer's disease (AD) poses a significant obstacle in today's healthcare landscape, with limited effective treatments. Recent studies have revealed encouraging findings about how exercise-triggered irisin might help slow down the advancement of AD. Irisin, a myokine, released during physical activity, has garnered significant attention for its pleiotropic effects, extending beyond its traditional role in metabolic regulation. This review explores irisin's multifaceted potential in combating AD. Research indicates that irisin enhances synaptic plasticity, crucial for learning and memory, and exhibits neuroprotective properties that may slow AD progression by safeguarding neurons from degeneration. Additionally, irisin's ability to modulate inflammatory responses is significant, as neuroinflammation is a key feature of AD pathology. Irisin may also influence the metabolism and clearance of amyloid-beta plaques and tau tangles, hallmark pathological markers of AD. Furthermore, irisin boosts brain-derived neurotrophic factor expression, vital for neuronal health, and improves insulin glucose regulation, addressing impaired brain insulin signaling observed in AD. Exercise-induced irisin presents a non-pharmacological strategy, leveraging physical activity's brain health benefits. Future research should focus on elucidating irisin's mechanisms and conducting clinical trials to assess its therapeutic efficacy and safety in AD patients. Overall, irisin therapy offers a promising avenue for AD treatment, potentially slowing disease progression and enhancing cognitive function, paving the way for innovative therapeutic strategies in the fight against AD.

UHPLC-Q Exactive-Orbitrap-MS and network pharmacology analyses to investigate the mechanism by which Danggui-Shaoyao-San affects 27-OHC-induced cell damage in SH-SY5Y/C6 coculture

BACKGROUND

Danggui-Shaoyao-San (DSS) is a classic Chinese medicine formula that has been extensively studied for its efficacy in treating Alzheimer's disease (AD). However, its mechanism of action is still unclear.

METHODS

In this study, UHPLC-Q Exactive-Orbitrap-MS was used to analyze and identify the compounds in DSS. Network pharmacology was used to analyze the common targets of drug-containing serum chemistries and AD, as well as the AD pathways in which drug-containing serum chemistries may be involved. The 27-OHC-induced SH-SY5Y/C6 coculture cell injury model was used to explore the mechanism of action of DSS in the treatment of AD.

RESULTS

UHPLC-Q Exactive-Orbitrap-MS analysis identified 73 chemical constituents in DSS aqueous extract and 39 compounds in drug-containing serum. According to network pharmacology analysis, DSS and AD share 181 common targets, with interleukin-6 (IL-6) and tumor necrosis factor (TNF) being the main effective targets. Furthermore, DSS may treat AD through the modulation of lipid metabolism-related pathways and the interleukin-17 (IL-17) signaling pathway. 27-hydroxycholesterol acid (27-OHC) significantly reduced the viability of SH-SY5Y cells and C6 cells in vitro, while DSS administration upregulated the expression of cytochrome P450 46A1 (CYP46A1) and cytochrome P450 7B1 (CYP7B1) enzymes and reduced cholesterol levels in SH-SY5Y cells. Additionally, DSS decreased reactive oxygen species (ROS) levels and increased glutathione (GSH) levels in coculture systems. DSS downregulated the expression of IL-17 in 27-OHC-injured SH-SY5Y cells and downregulated the expression of TNF-α, IL-6 and transforming growth factor-β1 (TGF-β1) in 27-OHC-injured C6 cells.

CONCLUSION

This study revealed the effective components, targets and mechanisms of DSS in the treatment of AD, highlighting the significant potential of DSS in treating this disease.

Quantification and correlation of amyloid-β plaque load, glial activation, GABAergic interneuron numbers, and cognitive decline in the young TgF344-AD rat model of Alzheimer's disease

Background

Animal models of Alzheimer's disease (AD) are essential tools for investigating disease pathophysiology and conducting preclinical drug testing. In this study, we examined neuronal and glial alterations in the hippocampus and medial prefrontal cortex (mPFC) of young TgF344-AD rats and correlated these changes with cognitive decline and amyloid-β plaque load.

Methods

We compared TgF344-AD and non-transgenic littermate rats aged 7-8 months of age. We systematically quantified β-amyloid plaques, astrocytes, microglia, four different subtypes of GABAergic interneurons (calretinin-, cholecystokinin-, parvalbumin-, and somatostatin-positive neurons), and newly generated neurons in the hippocampus. Spatial learning and memory were assessed using the Barnes maze test.

Results

Young TgF344-AD rats had a large number of amyloid plaques in both the hippocampus and mPFC, together with a pronounced increase in microglial cell numbers. Astrocytic activation was significant in the mPFC. Cholecystokinin-positive cell numbers were decreased in the hippocampus of transgenic rats, but calretinin-, parvalbumin-, and somatostatin-positive cell numbers were not altered. Adult neurogenesis was not affected by genotype. TgF344-AD rats had spatial learning and memory impairments, but this cognitive deficit did not correlate with amyloid plaque number or cellular changes in the brain. In the hippocampus, amyloid plaque numbers were negatively correlated with cholecystokinin-positive neuron and microglial cell numbers. In the mPFC, amyloid plaque number was negatively correlated with the number of astrocytes.

Conclusion

Pronounced neuropathological changes were found in the hippocampus and mPFC of young TgF344-AD rats, including the loss of hippocampal cholecystokinin-positive interneurons. Some of these neuropathological changes were negatively correlated with amyloid-β plaque load, but not with cognitive impairment.

Neuroprotective effects of chitinase-1 and calcitonin gene-related peptide on Alzheimer's disease by promoting lysosomal function

BACKGROUND

The amyloid cascade hypothesis still dominates in Alzheimer's disease (AD), and the acceleration of the clearance efficiency of amyloid-β (Aβ) has been always considered as an effective treatment option to slow the occurrence and progression of AD.

OBJECTIVE

This study aims to explore the role of zkscan3 and its related pathways in AD of the microglia-mediated pathogenesis, and whether the combined effect of drugs can exert neuroprotective function.

METHODS

N9 mouse microglia and HT-22 mouse hippocampal neurons were randomly divided into 6 groups, qRT-PCR technique was used to detect the gene expression level of zkscan3 and the genes related to lysosome generation and function. Fourteen C57 mice were randomly divided into two groups, and drug intervention model mice were randomly selected to establish from the AD group. Transmission electron microscope was used to detect the cell status and lysosome function in the hippocampus together with the other two groups.

RESULTS

Compared with the AD model group, the gene expression of zkscan3 in the drug intervention group was downregulated, and the degree of neuronal injury in the hippocampus was reduced, the structure and number of synapses were improved, and the function of intracellular lysosome was enhanced.

CONCLUSIONS

Zkscan3 and its related genes play a vital role in the development of AD. CGRP and CHIT-1, as a combined intervention, imparts effects through zkscan3-related pathways to improve lysosomal function and exert certain neuroprotective effects.

Involvement of CRMP2 Phosphorylation in Amyloid Beta-induced Tau Phosphorylation of Hippocampal Neurons in Alzheimer's Disease Mouse Model

Alzheimer's disease (AD) is the most common form of dementia, characterized by amyloid-β (Aβ) deposition and the formation of neurofibrillary tangles composed of hyperphosphorylated tau. Collapsin response mediator protein 2 (CRMP2), a microtubule (MT)-binding protein, regulates MT dynamics and is phosphorylated at Ser522 by cyclin-dependent kinase 5. Previous studies have shown increased CRMP2 phosphorylation at Ser522 (CRMP2-pSer522) in early AD stages and AD mouse models, where it colocalizes with phosphorylated tau. However, the role of CRMP-pSer522 in AD pathology remains unclear. In this study, we generated double transgenic mice by crossing tau Tg (PS19) mice and CRMP2 S522A knock-in (CRMP2KI) mice, in which S522 of CRMP2 was replaced with alanine to create a phospho-defective model. No significant change in tau phosphorylation was observed in the hippocampus of tau Tg; CRMP2KI mice compared to tau Tg littermates. However, when Aβ25-35 oligomers were injected into the hippocampus, tau phosphorylation was significantly reduced in Aβ-injected tau Tg; CRMP2KI mice compared to Aβ-injected tau Tg controls. These findings suggest that CRMP2 phosphorylation at Ser522 promotes Aβ-induced tau phosphorylation in this mouse model of AD.

Residual microglia following short-term PLX5622 treatment in 5xFAD mice exhibit diminished NLRP3 inflammasome and mTOR signaling, and enhanced autophagy

While moderately activated microglia in Alzheimer's disease (AD) are pivotal in clearing amyloid beta (Aβ), hyperactivated microglia perpetuate neuroinflammation. Prior investigations reported that the elimination of ~80% of microglia through inhibition of the colony-stimulating factor 1 receptor (CSF1R) during the advanced stage of neuroinflammation in 5xFamilial AD (5xFAD) mice mitigates synapse loss and neurodegeneration. Furthermore, prolonged CSF1R inhibition diminished the development of parenchymal plaques. Nonetheless, the effects of short-term CSF1R inhibition during the early stages of neuroinflammation on residual microglia are unknown. Therefore, we investigated the effects of 10-day CSF1R inhibition using PLX5622 in three-month-old female 5xFAD mice, a stage characterized by the onset of neuroinflammation and minimal Aβ plaques. We observed ~65% microglia depletion in the hippocampus and cerebral cortex. The leftover microglia displayed a noninflammatory phenotype with reduced NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome complexes. Moreover, plaque-associated microglia were reduced with diminished Clec7a expression. Additionally, phosphorylated S6 ribosomal protein and the protein sequestosome 1 analysis suggested reduced mechanistic targets of rapamycin (mTOR) signaling and autophagy in microglia and neurons within the hippocampus and cerebral cortex. Biochemical assays validated the inhibition of NLRP3 inflammasome activation, decreased mTOR signaling in the hippocampus and cerebral cortex, and enhanced autophagy in the hippocampus. However, short-term CSF1R inhibition did not influence Aβ plaques, soluble Aβ-42 levels, astrocyte hypertrophy, or hippocampal neurogenesis. Thus, short-term CSF1R inhibition during the early stages of neuroinflammation in 5xFAD mice promotes the retention of homeostatic microglia with diminished inflammasome activation and mTOR signaling, alongside increased autophagy.

Dihydro-resveratrol ameliorates NLRP3 inflammasome-mediated neuroinflammation via Bnip3-dependent mitophagy in Alzheimer's disease

BACKGROUND AND PURPOSE

Dihydro-resveratrol (DHR), a polyphenol derivative, that has been demonstrated to suppress inflammation-mediated injury. However, it is still unknown whether it has anti-neuroinflammatory and neuroprotective effects, and a therapeutic action in Alzheimer's disease (AD).

EXPERIMENTAL APPROACH

The anti-inflammatory and anti-Alzheimer's disease actions of dihydro-resveratrol were investigated using lipopolysaccharide (LPS) and AD mice models, and primary microglial cells. The changes in behaviour in mice were detected by the Morris water maze test and open-field test. Flow cytometry assay, western blotting, immunofluorescence assays and co-immunoprecipitation were used to investigate the changes in the NLRP3 inflammasome activation and mitophagy.

KEY RESULTS

In this study, in vivo observations indicated that the administration of dihydro-resveratrol (DHR) dramatically restored spatial learning, memory ability, autophagy and mitophagy, attenuated NLRP3 inflammasome activation, neuroinflammation and amyloid precursor protein pathology in LPS mice and AD mice. In addition, the inhibition of autophagy and mitophagy, or the activation of NLRP3 in vivo greatly abolished DHR-generated therapeutic efficacy on neuroinflammation, amyloid precursor protein pathology and cognitive loss. Further examination indicated that the application of DHR after the LPS and ATP exposure significantly inhibited the NLRP3 inflammasome activation, neuroinflammation and enhanced autophagic and mitophagic activation in microglia. Additionally, in vitro results show that DHR protects microglial cells against LPS and ATP-induced cytotoxicity by inhibiting NLRP3 inflammasome through activating Bnip3-dependent mitophagy and ULK phosphorylation.

CONCLUSIONS AND IMPLICATIONS

In summary, these findings suggest that dihydro-resveratrol (DHR) possesses potent anti-neuroinflammatory property and can act as a potential therapeutic agent for the treatment of AD.

HLA is a potent immunoinflammatory target in asymptomatic Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disease, neuroinflammation is an early pathological feature of AD. However, the alteration of the immune microenvironment in asymptomatic AD was not fully explained. In this study, we aimed to utilize the transcriptome data of AD patients in public databases to reveal the change of immune microenvironment in asymptomatic AD and screen the potential drug targets. A series of bioinformatics analyses were done, including differentially expressed genes (DEGs) screening, enrichment analysis, PPI network construction, and hub gene identification. Meanwhile, the selected hub genes were validated in APP/PS-1(AD) mice. Importantly, seven enrichment pathways and eight hub genes associated with inflammation were identified in asymptomatic AD. Correspondingly, more hub genes were increased in the hippocampus in AD mice compared to the other four brain regions. Accompanied by the activation of microglia and astrocytes, the inflammatory cytokines were increased in the hippocampus of AD mice. Subsequently, the relationship between HLA-C and inflammation was evaluated in AD mice. HLA-C was correlated with the activation of microglia, and HLA-DRB1 with IL-6 in the hippocampus. Moreover, HLA-C is expressed in the microglia cells and astrocytes. Further, five FDA-approved drugs (Itrazole, Dfo, Syrosingopine, Cefoperazone, and Pradaxa) were predicted as the common drug targeting HLA-C and HLA-DRB1 by molecular docking. Taken together, the results revealed the changes in the immune microenvironment of asymptomatic AD and provided a new perspective for the development of anti-inflammatory drugs for AD early treatment.

Microglial double stranded DNA accumulation induced by DNase II deficiency drives neuroinflammation and neurodegeneration

BACKGROUND

Deoxyribonuclease 2 (DNase II) is pivotal in the clearance of cytoplasmic double stranded DNA (dsDNA). Its deficiency incurs DNA accumulation in cytoplasm, which is a hallmark of multiple neurodegenerative diseases. Our previous study showed that neuronal DNase II deficiency drove tau hyperphosphorylation and neurodegeneration (Li et al., Transl Neurodegener 13:39, 2024). Although it has been verified that DNase II participates in type I interferons (IFN-I) mediated autoinflammation and senescence in peripheral systems, the role of microglial DNase II in neuroinflammation and neurodegenerative diseases such as Alzheimer's disease (AD) is still unknown.

METHODS

The levels of microglial DNase II in triple transgenic AD mice (3xTg-AD) were measured by immunohistochemistry. The cognitive performance of microglial DNase II deficient WT and AD mice was determined using the Morris water maze test, Y-maze test, novel object recognition test and open filed test. To investigate the impact of microglial DNase II deficiency on microglial morphology, cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway and IFN-I pathway, neuroinflammation, synapses loss, amyloid pathology and tauopathy, the levels of cGAS-STING and IFN-I pathway related protein, gliosis and proinflammatory cytokines, synaptic protein, complement protein, Aβ levels, phosphorylated tau in the brains of the microglial DNase II deficient WT and AD mice were evaluated by immunolabeling, immunoblotting, q-PCR or ELISA.

RESULTS

We found that the levels of DNase II were significantly decreased in the microglia of 3xTg-AD mice. Microglial DNase II deficiency altered microglial morphology and transcriptional signatures, activated the cGAS-STING and IFN-I pathway, initiated neuroinflammation, led to synapse loss via complement-dependent pathway, increased Aβ levels and tauopathy, and induced cognitive decline.

CONCLUSIONS

Our study shows the effect of microglial DNase II deficiency and cytoplasmic accumulated dsDNA on neuroinflammation, and reveals the initiatory mechanism of AD pathology, suggesting that DNase II is a potential target for neurodegenerative diseases.

The gut-brain axis: Unveiling the impact of xenobiotics on neurological health and disorders

The Gut-Brain Axis (GBA) is a crucial link between the gut microbiota and the central nervous system. Xenobiotics, originating from diverse sources, play a significant role in shaping this interaction. This review examines how these compounds influence neurotransmitter dynamics within the GBA. Environmental pollutants can disrupt microbial populations, impacting neurotransmitter synthesis-especially serotonin, gamma-aminobutyric acid (GABA), and dopamine pathways. Such disruptions affect mood regulation, cognition, and overall neurological function. Xenobiotics also contribute to the pathophysiology of neurological disorders, with changes in serotonin levels linked to mood disorders and imbalances in GABA and dopamine associated with anxiety, stress, and reward pathway disorders. These alterations extend beyond the GBA, leading to complications in neurological health, including increased risk of neurodegenerative diseases due to neuroinflammation triggered by neurotransmitter imbalances. This review provides a comprehensive overview of how xenobiotics influence the GBA and their implications for neurological well-being.

A domestic strain of Lactobacillus rhamnosus attenuates cognitive deficit and pro-inflammatory cytokine expression in an animal model of Alzheimer's disease

BACKGROUND

Microbiome dysbiosis plays a significant role in neuroinflammation and Alzheimer's disease (AD). Therefore, gut microbiome restoration using appropriate probiotics may be beneficial in alleviating AD features. In this study, we investigated the effects of a domestic strain of Lactobacillus rhamnosus (L. rhamnosus) on spatial memory, and cytokines expression in an inflammation-based AD model.

METHOD

Male Wistar rats were randomly divided into four groups (six animals per group) of control, L. rhamnosus-only, D-galactose (D-gal)-only, and D-gal + L. rhamnosus. Spatial learning and memory were assessed using the Morris water maze test. IL-1β, IL-6, and TNF-α expression levels were measured using Real-Time qPCR. A significance level of 0.05 was used for statistical analysis.

RESULTS

In contrast to the D-gal + L. rhamnosus-treated group, D-gal only treated group showed impaired memory in MWM test compared to the control group. Additionally, D-gal treatment resulted in an increase in IL-1β and TNF-α levels and a decrease in IL-6 levels, which was not statistically significant. However, the TNF-α level was significantly decreased in D-gal + L. rhamnosus-treated group compared to D-gal-only treated group (P < 0.05). Also, IL-6 level was significantly lower in D-gal + L. rhamnosus-treated group compared to control group (P < 0.05).

CONCLUSION

These results suggest that the domestic L. rhamnosus might positively impact cognitive deficit and neuroinflammation. Further studies are suggested to investigate the specific mechanisms mediating the effects of L. rhamnosus on cognitive functions and neuroinflammation in animal models of AD.

Heavy metals exposure and Alzheimer's disease: Underlying mechanisms and advancing therapeutic approaches

Heavy metals such as lead, cadmium, mercury, and arsenic are prevalent in the environment due to both natural and anthropogenic sources, leading to significant public health concerns. These heavy metals are known to cause damage to the nervous system, potentially leading to a range of neurological conditions including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and attention-deficit hyperactivity disorder (ADHD). The present study examines the complex relationship between heavy metal exposure and AD, focusing on the underlying mechanisms of toxicity and potential therapeutic approaches. This review article highlights how these metals can impair brain function through mechanisms such as oxidative stress, inflammation, and neurotransmitter disruption, ultimately contributing to neurodegenerative diseases like AD. It also addresses the challenges in diagnosing heavy metal-induced cognitive impairments and emphasizes the need for further research to explore effective treatment strategies and preventive measures against heavy metal exposure.

Hippocampal GPR35 Participates in the Pathogenesis of Cognitive Deficits and Emotional Alterations Induced by Aβ1-42 in Mice

The amyloid-beta (Aβ) aggregation in Alzheimer's disease (AD) triggers neuroinflammation, and neurodegeneration, which lead to cognitive deficits along with other neuropsychiatric symptoms, including depression and anxiety. G protein-coupled receptor 35 (GPR35) is expressed in the brain and is involved in metabolic stresses. However, the role of GPR35 in AD pathogenesis remains unknown. Herein, pharmacological blockade, shRNA-mediated knockdown or knockout of GPR35 was performed to investigate the role and mechanisms of GPR35 in Aβ1-42-induced cognitive impairment and emotional alterations in mice. A series of behavioral, histopathological, and biochemical tests were performed in mice. Our results showed that hippocampal GPR35 expression was significantly increased in Aβ1-42-induced and APP/PS1 AD mouse models. Pharmacological blockade or knockdown of GPR35 ameliorated cognitive impairment and emotional alterations induced by Aβ1-42 in mice. We also found that blockade or knockdown of GPR35 decreased the accumulation of Aβ, and improved neuroinflammation, cholinergic system deficiency, and neuronal apoptosis via the RhoA/ROCK2 pathway in Aβ1-42-treaed mice. However, activation of GPR35 aggravates Aβ1-42-induced cognitive deficits and emotional alterations in mice. In addition, genetic deletion of GPR35 protects against the Aβ1-42-induced cognitive deficits and emotional alterations in mice. Moreover, GPR35 could bind to TLR4. These results indicate that GPR35 participates in the pathogenesis of cognitive deficits and emotional alterations induced by Aβ1-42 in mice, suggesting that GPR35 could be a potential therapeutic target for AD.

The Gut Microbiota-Brain Axis: A New Frontier in Alzheimer's Disease Pathology

Dr. Aloysius Alzheimer, a German neuropathologist and psychiatrist, recognized the primary instance of Alzheimer's disease (AD) for a millennium, and this ailment, along with its related dementias, remains a severe overall community issue related to health. Nearly fifty million individuals worldwide suffer from dementia, with Alzheimer's illness contributing to between 60 and 70% of the instances, estimated through the World Health Organization. In addition, 82 million individuals are anticipated to be affected by the global dementia epidemic by 2030 and 152 million by 2050. Furthermore, age, environmental circumstances, and inherited variables all increase the likelihood of acquiring neurodegenerative illnesses. Most recent pharmacological treatments are found in original hypotheses of disease, which include cholinergic (drugs that show affective cholinergic system availability) as well as amyloid-accumulation (a single drug is an antagonist receptor of Nmethyl D-aspartate). In 2020, the FDA provided approval on anti-amyloid drugs. According to mounting scientific data, this gut microbiota affects healthy physiological homeostasis and has a role in the etiology of conditions that range between obesity and neurodegenerative disorders like Alzheimer's. The microbiota-gut-brain axis might facilitate interconnection among gut microbes as well as the central nervous system (CNS). Interaction among the microbiota-gut system as well as the brain occurs through the "two-way" microbiota-gut-brain axis. Along this axis, the stomach as well as the brain develop physiologically and take on their final forms. This contact is constant and is mediated by numerous microbiota-derived products. The gut microbiota, for instance, can act as non-genetic markers to set a threshold for maintaining homeostasis or getting ill. The scientific community has conducted research and found that bowel dysbiosis and gastrointestinal tract dysregulation frequently occur in Alzheimer's disease (AD) patients. In this review, the effects of the microbiota- gut-brain axis on AD pathogenesis will be discussed.

Investigation of Novel Aronia Bioactive Fraction-Alginic Acid Nanocomplex on the Enhanced Modulation of Neuroinflammation and Inhibition of Aβ Aggregation

BACKGROUND/OBJECTIVES

Aronia extract or its active compounds, especially anthocyanin, have shown potential for Alzheimer's disease (AD)-related pathologies, including neuroinflammation, fibrillogenesis of amyloid beta (Aβ), and cognitive impairment. However, there was still concern about their structural instability in vivo and in vitro. To solve the instability of anthocyanins, we combined aronia bioactive factions (ABFs) and alginic acid via electrostatic molecular interactions and created an ABF-alginic acid nanocomplex (AANCP). We evaluated whether it is more stable and effective in cognitive disorder mice and neuroinflammation cell models.

METHODS

The physicochemical properties of the AANCP, such as nanoparticle size, structural stability, and release rate, were characterized. The AANCP was administered to scopolamine-injected Balb/c mice, and to BV2 microglia treated with lipopolysaccharide (LPS) and amyloid beta (Aβ). Inflammation responses were measured via qPCR and ELISA in vitro, and cognitive functions were measured via behavior tests in vivo.

RESULTS

The AANCP readily formed nanoparticles, 209.6 nm in size, with a negatively charged zeta potential. The AANCP exhibited better stability in four plasma samples (human, dog, rat, and mouse) and was slowly released in different pH conditions (pH 2.0, 7.4, and 8.0) compared with non-complexedABF. In vitro studies on microglial cells treated with AANCPs revealed a suppression of inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6) induced by LPS. The AANCP increased microglial Aβ phagocytosis through the activation of triggering receptor expressed on myeloid cell 2 (TREM2)-related microglial polarization. The AANCP inhibited aggregation of Aβ in vitro and alleviated cognitive impairment in a scopolamine-induced in vivo dementia mouse model.

CONCLUSIONS

Our data indicate that AANCPs are more stable than ABFs and effective for cognitive disorders and neuroinflammation via modulation of M2 microglial polarization.

Maresin-like 1 Ameliorates Neuropathology of Alzheimer's Disease in Brains of a Transgenic Mouse Model

(1) Background: Impeded resolution of inflammation contributes substantially to the pathogenesis of Alzheimer's disease (AD); consequently, resolving inflammation is pivotal to the amelioration of AD pathology. This can potentially be achieved by the treatment with specialized pro-resolving lipid mediators (SPMs), which should resolve neuroinflammation in brains. (2) Methods: Here, we report the histological effects of long-term treatment with an SPM, maresin-like 1 (MarL1), on AD pathogenesis in a transgenic 5xFAD mouse model. (3) Results: MarL1 treatment reduced Aβ overload, curbed the loss of neurons in brains especially cholinergic neurons associated with cleaved-caspase-3-associated apoptotic degeneration, reduced microgliosis and the pro-inflammatory M1 polarization of microglia, curbed the AD-associated decline in anti-inflammatory Iba1+Arg-1+-M2 microglia, inhibited phenotypic switching to pro-inflammatory N1 neutrophils, promoted the blood-brain barrier-associated tight-junction protein claudin-5 and decreased neutrophil leakage in 5xFAD brains, and induced the switch of neutrophils toward the inflammation-resolving N2 phenotype. (4) Conclusions: Long-term administration of MarL1 mitigates AD-related neuropathogenesis in brains by curbing neuroinflammation and neurodegeneration, based on the histological results. These findings provide preclinical leads and mechanistic insights for the development of MarL1 into an effective modality to ameliorate AD pathogenesis.

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

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

A Review of the Consequences of Gut Microbiota in Neurodegenerative Disorders and Aging

Age-associated alterations in the brain lead to cognitive deterioration and neurodegenerative disorders (NDDs). This review with a particular focus on Alzheimer's disease (AD), emphasizes the burgeoning significance of the gut microbiota (GMB) in neuroinflammation and its impact on the gut-brain axis (GBA), a communication conduit between the gut and the central nervous system (CNS). Changes in the gut microbiome, including diminished microbial diversity and the prevalence of pro-inflammatory bacteria, are associated with AD pathogenesis. Promising therapies, such as fecal microbiota transplantation (FMT), probiotics, and prebiotics, may restore gut health and enhance cognitive performance. Clinical data remain insufficient, necessitating further research to elucidate causes, enhance therapy, and consider individual variances. This integrative approach may yield innovative therapies aimed at the GMB to improve cognitive function and brain health in older people.

Rotating magnetic field improved cognitive and memory impairments in a sporadic ad model of mice by regulating microglial polarization

Neuroinflammation, triggered by aberrantly activated microglia, is widely recognized as a key contributor to the initiation and progression of Alzheimer's disease (AD). Microglial activation in the central nervous system (CNS) can be classified into two distinct phenotypes: the pro-inflammatory M1 phenotype and the anti-inflammatory M2 phenotype. In this study, we investigated the effects of a non-invasive rotating magnetic field (RMF) (0.2T, 4Hz) on cognitive and memory impairments in a sporadic AD model of female Kunming mice induced by AlCl3 and D-gal. Our findings revealed significant improvements in cognitive and memory impairments following RMF treatment. Furthermore, RMF treatment led to reduced amyloid-beta (Aβ) deposition, mitigated damage to hippocampal morphology, prevented synaptic and neuronal loss, and alleviated cell apoptosis in the hippocampus and cortex of AD mice. Notably, RMF treatment ameliorated neuroinflammation, facilitated the transition of microglial polarization from M1 to M2, and inhibited the NF-кB/MAPK pathway. Additionally, RMF treatment resulted in reduced aluminum deposition in the brains of AD mice. In cellular experiments, RMF promoted the M1-M2 polarization transition and enhanced amyloid phagocytosis in cultured BV2 cells while inhibiting the TLR4/NF-кB/MAPK pathway. Collectively, these results demonstrate that RMF improves memory and cognitive impairments in a sporadic AD model, potentially by promoting the M1 to M2 transition of microglial polarization through inhibition of the NF-кB/MAPK signaling pathway. These findings suggest the promising therapeutic applications of RMF in the clinical treatment of AD.

Irisin and neuroinflammation: Challenges and opportunities

Irisin is a myokine that is cleaved from 5-domain type III fibronectin (FNDC5), and is known for its metabolic functions as it stimulates browning of white adipose tissue; similarly, effects on the central nervous system have been described, specifically in neurodevelopmental and neuroprotection processes. The purpose of this review is to describe recent information on the effects of irisin on neuroinflammation to contribute to the knowledge about the mechanisms by which irisin and exercise could generate benefits for some neurological diseases. The review conducted found several studies describing the effect of irisin on pathways such as STAT3, p38, cAMP/PKA/CREB, as well as effects on GFAP protein expression or apoptosis processes in both in vitro and in vivo models; likewise, these pathways are associated with better BDNF expression. Despite increasing information on this topic, it is still necessary to clarify the mechanisms by which irisin has effects on neuroinflammation and this could represent an opportunity to generate more treatments for diseases such as Alzheimer's, Parkinson's or Diabetes Mellitus.

The Role of Reactive Oxygen Species in Alzheimer's Disease: From Mechanism to Biomaterials Therapy

Alzheimer's disease (AD) is a chronic, insidious, and progressive neurodegenerative disease that remains a clinical challenge for society. The fully approved drug lecanemab exhibits the prospect of therapy against the pathological processes, while debatable adverse events conflict with the drug concentration required for the anticipated therapeutic effects. Reactive oxygen species (ROS) are involved in the pathological progression of AD, as has been demonstrated in much research regarding oxidative stress (OS). The contradiction between anticipated dosage and adverse event may be resolved through targeted transport by biomaterials and get therapeutic effects through pathological progression via regulation of ROS. Besides, biomaterials fix delivery issues by promoting the penetration of drugs across the blood-brain barrier (BBB), protecting the drug from peripheral degradation, and elevating bioavailability. The goal is to comprehensively understand the mechanisms of ROS in the progression of AD disease and the potential of ROS-related biomaterials in the treatment of AD. This review focuses on OS and its connection with AD and novel biomaterials in recent years against AD via OS to inspire novel biomaterial development. Revisiting these biomaterials and mechanisms associated with OS in AD via thorough investigations presents a considerable potential and bright future for improving effective interventions for AD.

An in situ-activated and chemi-excited photooxygenation system based on G-poly(thioacetal) for Aβ1-42 aggregates

The abnormal aggregation of Aβ proteins, inflammatory responses, and mitochondrial dysfunction have been reported as major targets in Alzheimer's disease (AD). Photooxygenation of the amyloid-β peptide (Aβ) is viewed as a promising therapeutic intervention for AD treatment. However, the limitations of the depth of the external light source passing through the brain and the toxic side effects on healthy tissues are two significant challenges in the photooxidation of Aβ aggregates. We proposed a method to initiate the chemical stimulation of Aβ1-42 aggregate oxidation through H2O2 and correct the abnormal microenvironment of the lesions by eliminating the cascading reactions of oxidative stress. The degradable G-poly(thioacetal) undergoes cascade release of cinnamaldehyde (CA) and thioacetal triggered by endogenous H2O2, with CA in turn amplifying degradation by generating more H2O2 through mitochondrial dysfunction. A series of novel photosensitizers have been prepared and synthesized for use in the photodynamic oxidation of Aβ1-42 aggregates under white light activation. The nanoparticles (BD-6-QM/NPs) self-assembled from BD-6-QM, bis[2,4,5-trichloro-6-(pentoxycarbonyl) phenyl] ester (CPPO), and G-poly(thioacetal) not only exhibit H2O2-stimulated controlled release but also can be chemically triggered by H2O2 to generate singlet oxygen to inhibit Aβ1-42 aggregates, reducing the Aβ1-42-induced neurotoxicity.

Thyroid Hormone Supplementation Restores Cognitive Deficit, Insulin Signaling, and Neuroinflammation in the Hippocampus of a Sporadic Alzheimer's-like Disease Rat Model

Thyroid hormones play a crucial role in the development of the central nervous system and are considered pivotal to cognitive functions in the adult brain. Recently, thyroid dysfunction has been associated with Alzheimer's disease. The aim of this study was to assess the neuroprotective effects of triiodothyronine (T3) on insulin signaling, neuroinflammation, apoptosis, and cognitive function in a streptozotocin (STZ)-induced sporadic Alzheimer's disease-like model. Male Wistar rats underwent stereotaxic surgery for intracerebroventricular injections of streptozotocin (STZ; 2 mg/kg) or vehicle in the lateral ventricles to induce an AD-like model. The animals received a daily dose of 1.5 μg of T3/100 g body weight or the same volume of vehicle for 30 days and were subdivided into four experimental groups: (1) animals receiving citrate treated with saline (Control = CTL); (2) animals receiving citrate treated with T3 (T3); (3) animals receiving STZ treated with saline (STZ); and (4) animals receiving STZ treated with T3 (STZ + T3). The novel object recognition test was used to measure cognitive function. Serum analysis, real-time RT-PCR, immunohistochemistry, and immunoblotting analyses were also carried out. Our results demonstrated that T3 treatment reversed cognitive impairment and increased Akt and GSK3 phosphorylation in the treated group, while also reducing microglial activation (Iba-1) and GFAP expression (reactive astrocytes), along with TNF-α, IL-6, and IL-1β levels in the hippocampus. Additionally, T3 treatment increased levels of the anti-apoptotic protein Bcl-2 and reduced the expression of the pro-apoptotic protein BAX in the hippocampus. Our study demonstrated that T3 could potentially protect neurons in an AD model induced by STZ.

Intravenous chaperone treatment of late-stage Alzheimer´s disease (AD) mouse model affects amyloid plaque load, reactive gliosis and AD-related genes

Treatment strategies that are efficient against established Alzheimer's disease (AD) are needed. BRICHOS is a molecular chaperone domain that prevents amyloid fibril formation and associated cellular toxicity. In this study, we treated an AD mouse model seven months after pathology onset, using intravenous administration of recombinant human (rh) Bri2 BRICHOS R221E. Two injections of rh Bri2 BRICHOS R221E per week for three months in AD mice reduced amyloid β (Aβ) burden, and mitigated astro- and microgliosis, as determined by glial fibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule 1 (Iba1) immunohistochemistry. Sequencing of RNA from cortical microglia cells showed that BRICHOS treatment normalized the expression of identified plaque-induced genes in mice and humans, including clusterin and GFAP. Rh Bri2 BRICHOS R221E passed the blood-brain barrier (BBB) in age-matched wild-type mice as efficiently as in the AD mice, but then had no effect on measures of AD-like pathology, and mainly affected the expression of genes that affect cellular shape and movement. These results indicate a potential of rh Bri2 BRICHOS against advanced AD and underscore the ability of BRICHOS to target amyloid-induced pathology.

Naringin and Naringenin: Potential Multi-Target Agents for Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common forms of neurodegenerative dementia. The etiology of AD is multifactorial, and its complex pathophysiology involves tau and amyloid-β deposition, increased oxidative stress, neuroinflammation, metabolic disorders, and massive neuronal loss. Due to its complex pathology, no effective cure for AD has been found to date. Therefore, there is an unmet clinical need for the development of new drugs against AD. Natural products are known to be good sources of compounds with pharmacological activity and have potential for the development of new therapeutic agents. Naringin, a naturally occurring flavanone glycoside, is predominantly found in citrus fruits and Chinese medicinal herbs. Mounting evidence shows that naringin and its aglycone, naringenin, have direct neuroprotective effects on AD, such as anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, and anti-neuroinflammatory effects, as well as metal chelation. Furthermore, they are known to improve disordered glucose/lipid metabolism, which is a high risk factor for AD. In this review, we summarize the latest data on the impact of naringin and naringenin on the molecular mechanisms involved in AD pathophysiology. Additionally, we provide an overview of the current clinical applications of naringin and naringenin. The novel delivery systems for naringin and naringenin, which can address their widespread pharmacokinetic limitations, are also discussed. The literature indicates that naringin and naringenin could be multilevel, multitargeted, and multifaceted for preventing and treating AD.

Inflammation in Metal-Induced Neurological Disorders and Neurodegenerative Diseases

Essential metals play critical roles in maintaining human health as they participate in various physiological activities. Nonetheless, both excessive accumulation and deficiency of these metals may result in neurotoxicity secondary to neuroinflammation and the activation of microglia and astrocytes. Activation of these cells can promote the release of pro-inflammatory cytokines. It is well known that neuroinflammation plays a critical role in metal-induced neurotoxicity as well as the development of neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). Initially seen as a defense mechanism, persistent inflammatory responses are now considered harmful. Astrocytes and microglia are key regulators of neuroinflammation in the central nervous system, and their excessive activation may induce sustained neuroinflammation. Therefore, in this review, we aim to emphasize the important role and molecular mechanisms underlying metal-induced neurotoxicity. Our objective is to raise the awareness on metal-induced neuroinflammation in neurological disorders. However, it is not only just neuroinflammation that different metals could induce; they can also cause harm to the nervous system through oxidative stress, apoptosis, and autophagy, to name a few. The primary pathophysiological mechanism by which these metals induce neurological disorders remains to be determined. In addition, given the various pathways through which individuals are exposed to metals, it is necessary to also consider the effects of co-exposure to multiple metals on neurological disorders.

Microglial senescence in neurodegeneration: Insights, implications, and therapeutic opportunities

The existing literature on neurodegenerative diseases (NDDs) reveals a common pathological feature: the accumulation of misfolded proteins. However, the heterogeneity in disease onset mechanisms and the specific brain regions affected complicates the understanding of the diverse clinical manifestations of individual NDDs. Dementia, a hallmark symptom across various NDDs, serves as a multifaceted denominator, contributing to the clinical manifestations of these disorders. There is a compelling hypothesis that therapeutic strategies capable of mitigating misfolded protein accumulation and disrupting ongoing pathogenic processes may slow or even halt disease progression. Recent research has linked disease-associated microglia to their transition into a senescent state-characterized by irreversible cell cycle arrest-in aging populations and NDDs. Although senescent microglia are consistently observed in NDDs, few studies have utilized animal models to explore their role in disease pathology. Emerging evidence from experimental rat models suggests that disease-associated microglia exhibit characteristics of senescence, indicating that deeper exploration of microglial senescence could enhance our understanding of NDD pathogenesis and reveal novel therapeutic targets. This review underscores the importance of investigating microglial senescence and its potential contributions to the pathophysiology of NDDs, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Additionally, it highlights the potential of targeting microglial senescence through iron chelation and senolytic therapies as innovative approaches for treating age-related NDDs.

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.

Trajectory of brain-derived amyloid beta in Alzheimer's disease: where is it coming from and where is it going?

Alzheimer's disease (AD) is a progressive neurological disorder that primarily impacts cognitive function. Currently there are no disease-modifying treatments to stop or slow its progression. Recent studies have found that several peripheral and systemic abnormalities are associated with AD, and our understanding of how these alterations contribute to AD is becoming more apparent. In this review, we focuse on amyloid‑beta (Aβ), a major hallmark of AD, summarizing recent findings on the source of brain-derived Aβ and discussing where and how the brain-derived Aβ is cleared in vivo. Based on these findings, we propose future strategies for AD prevention and treatment, from a novel perspective on Aβ metabolism.

Discovery of novel coumarin triazolyl and phenoxyphenyl triazolyl derivatives targeting amyloid beta aggregation-mediated oxidative stress and neuroinflammation for enhanced neuroprotection

This study involved designing, synthesizing, and evaluating the protective potential of compounds on microglial cells (BV-2 cells) and neurons (SH-SY5Y cells) against cell death induced by Aβ1-42. It aimed to identify biologically specific activities associated with anti-Aβ aggregation and understand their role in oxidative stress initiation and modulation of proinflammatory cytokine expression. Actively designed compounds CE5, CA5, PE5, and PA5 showed protective effects on BV-2 and SH-SY5Y cells, with cell viability ranging from 60.78 ± 2.32% to 75.38 ± 2.75% for BV-2 cells and 87.21% ± 1.76% to 91.55% ± 1.78% for SH-SY5Y cells. The transformation from ester in CE5 to amide in CA5 resulted in significant antioxidant properties. Molecular docking studies revealed strong binding of CE5 to critical Aβ aggregation regions, disrupting both intra- and intermolecular formations. TEM assessment supported CE5's anti-Aβ aggregation efficacy. Structural variations in PE5 and PA5 had diverse effects on IL-1β and IL-6, suggesting further specificity studies for Alzheimer's disease. Log P values suggested potential blood-brain barrier permeation for CE5 and CA5, indicating suitability for CNS drug development. In silico ADMET and toxicological screening revealed that CE5, PA5, and PE5 have favorable safety profiles, while CA5 shows a propensity for hepatotoxicity. According to this prediction, coumarin triazolyl derivatives are likely to exhibit mutagenicity. Nevertheless, CE5 and CA5 emerge as promising lead compounds for Alzheimer's therapeutic intervention, with further insights expected from subsequent in vivo studies.

Chemiexcitation-Triggered Photosensitizer Activation for Photooxidation of Aβ1-42 Aggregates

Oxidative degradation of the pathogenic amyloid-β-peptide (Aβ) aggregation is an effective and promising method to treat Alzheimer's disease under light irradiation. However, the limited penetration of external light sources into deep tissues has hindered the development of this treatment. Therefore, we have designed an unprecedented chemiluminescence-initiated photodynamic therapy system to replace external laser irradiation, primarily composed of d-glucose-based polyoxalate (G-poly(oxalate)), the novel photosensitizer (BD-Se-QM), and bis [2,4,5-trichloro-6-(pentoxy-carbonyl) phenyl] ester. BD-Se-QM possesses excellent singlet oxygen (1O2) generation efficiency and the ability to photooxidize Aβ1-42 aggregates under white light. G-poly(oxalate) not only helps the nanosystem to cross the blood-brain barrier but also has sufficient oxalate ester groups to significantly enhance the efficiency of chemiluminescence resonance energy transfer. The oxalate ester groups in BD-Se-QM/NPs can chemically react with H2O2 to produce high-energy intermediates that activate BD-Se-QM, which can generate 1O2 to inhibit Aβ1-42 aggregates and also promote microglial uptake of Aβ1-42, reducing the Aβ1-42-induced neurotoxicity. The chemically stimulated nanoplatform not only solves the drug delivery problem but also eliminates the need for external light sources. We anticipate that this chemically excited nanosystem could also be used for targeted delivery of other small molecule drugs.

N-Glycan profile of the cell membrane as a probe for lipopolysaccharide-induced microglial neuroinflammation uncovers the effects of common fatty acid supplementation

Altered N-glycosylation of proteins on the cell membrane is associated with several neurodegenerative diseases. Microglia are an ideal model for studying glycosylation and neuroinflammation, but whether aberrant N-glycosylation in microglia can be restored by diet remains unknown. Herein, we profiled the N-glycome, proteome, and glycoproteome of the human microglia following lipopolysaccharide (LPS) induction to probe the impact of dietary and gut microbe-derived fatty acids-oleic acid, lauric acid, palmitic acid, valeric acid, butyric acid, isobutyric acid, and propionic acid-on neuroinflammation using liquid chromatography-tandem mass spectrometry. LPS changed N-glycosylation in the microglial glycocalyx altering high mannose and sialofucosylated N-glycans, suggesting the dysregulation of mannosidases, fucosyltransferases, and sialyltransferases. The results were consistent as we observed the restoration effect of the fatty acids, especially oleic acid, on the LPS-treated microglia, specifically on the high mannose and sialofucosylated glycoforms of translocon-associated proteins, SSRA and SSRB along with the cell surface proteins, CD63 and CD166. In addition, proteomic analysis and in silico modeling substantiated the potential of fatty acids in reverting the effects of LPS on microglial N-glycosylation. Our results showed that N-glycosylation is likely affected by diet by restoring alterations following LPS challenge, which may then influence the disease state.

Platycodon grandiflorum exhibits anti-neuroinflammatory potential against beta-amyloid-induced toxicity in microglia cells

Background/objectives

Platycodon grandiflorum (PG) is used in traditional oriental medicine to treat several ailments.

Methods

The study investigated the anti-inflammatory and neuroprotective effects of PGW (P. grandiflorum) extract in Aβ25-35-induced inflammation in BV2 microglia cells.

Result

PGW demonstrated significant inhibition of nitric oxide (NO) production, with reductions of 30.4, 36.7, and 61.2% at concentrations of 50, 100, and 200 μg/mL, respectively. Moreover, PGW effectively suppressed the production of pro-inflammatory cytokines IL-1β and IL-6 and exhibited significant inhibitory activity against TNF-α at 200 μg/mL. Furthermore, PGW treatment mitigated apoptosis in Aβ-induced BV2 cells by modulating the mitochondrial apoptosis pathway, regulating Bcl-2 family protein synthesis, and inhibiting caspase activation. Mechanistically, PGW attenuated the activation of the MAPK (JNK, ERK, p38) pathway induced by Aβ, showing a concentration-dependent decrease in phosphorylation levels of these proteins. Additionally, PGW inhibited the NF-κB pathway activation by reducing the phosphorylation levels of p65 and IκBα in a concentration-dependent manner.

Conclusion

PGW demonstrated anti-inflammatory and neuroprotective effects in Aβ-induced neuronal cells, suggesting its potential as a therapeutic agent for neuroinflammatory associated with neurodegenerative diseases.

Ecklonia cava Ameliorates Cognitive Impairment on Amyloid β-Induced Neurotoxicity by Modulating Oxidative Stress and Synaptic Function in Institute of Cancer Research (ICR) Mice

This study investigated the neuroprotective effect of 70% ethanol extract of Ecklonia cava (EE) in amyloid beta (Aβ)-induced cognitive deficit mice. As a result of analyzing the bioactive compounds in EE, nine compounds were identified using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). In particular, the diekcol content was quantified by high-performance liquid chromatography with diode-array detection (DAD-HPLC). Biochemical analysis was performed on brain tissue to determine the mechanism of the cognitive function improvement effect of EE. The result showed that EE ameliorated learning and memory decline in behavioral tests on Aβ-induced mice. EE also attenuated oxidative stress by regulating malondialdehyde (MDA) content, reduced glutathione (GSH), and superoxide dismutase (SOD) levels. Similarly, EE also improved mitochondrial dysfunction as mitochondrial membrane potential, ATP production, and reactive oxygen species (ROS) levels. In addition, EE enhanced synapse function by modulating acetylcholine-related enzymes and synaptic structural proteins in the whole brain, hippocampus, and cerebral cortex tissues. Also, EE regulated Aβ-induced apoptosis and inflammation through the c-Jun N-terminal kinase (JNK) and nuclear factor-kappa B (NF-κB) signaling pathways. Furthermore, EE protected neurotoxicity by increasing brain-derived neurotrophic factor (BDNF) production. These results suggest that EE may be used as a dietary supplement for the prevention and treatment of Alzheimer's disease (AD).

The role of estrogen in Alzheimer's disease pathogenesis and therapeutic potential in women

Estrogens are pivotal regulators of brain function throughout the lifespan, exerting profound effects from early embryonic development to aging. Extensive experimental evidence underscores the multifaceted protective roles of estrogens on neurons and neurotransmitter systems, particularly in the context of Alzheimer's disease (AD) pathogenesis. Studies have consistently revealed a greater risk of AD development in women compared to men, with postmenopausal women exhibiting heightened susceptibility. This connection between sex factors and long-term estrogen deprivation highlights the significance of estrogen signaling in AD progression. Estrogen's influence extends to key processes implicated in AD, including amyloid precursor protein (APP) processing and neuronal health maintenance mediated by brain-derived neurotrophic factor (BDNF). Reduced BDNF expression, often observed in AD, underscores estrogen's role in preserving neuronal integrity. Notably, hormone replacement therapy (HRT) has emerged as a sex-specific and time-dependent strategy for primary cardiovascular disease (CVD) prevention, offering an excellent risk profile against aging-related disorders like AD. Evidence suggests that HRT may mitigate AD onset and progression in postmenopausal women, further emphasizing the importance of estrogen signaling in AD pathophysiology. This review comprehensively examines the physiological and pathological changes associated with estrogen in AD, elucidating the therapeutic potential of estrogen-based interventions such as HRT. By synthesizing current knowledge, it aims to provide insights into the intricate interplay between estrogen signaling and AD pathogenesis, thereby informing future research directions and therapeutic strategies for this debilitating neurodegenerative disorder.

PKCδ serves as a potential biomarker and therapeutic target for microglia-mediated neuroinflammation in Alzheimer's disease

INTRODUCTION

To investigate the role of a novel type of protein kinase C delta (PKCδ) in the neuroinflammation of Alzheimer's disease (AD).

METHODS

We analyzed PKCδ and inflammatory cytokines levels in cerebrospinal fluid (CSF) of AD and normal controls, as well as their correlations. The cellular expression pattern of PKCδ and the effects of PKCδ modulation on microglia-mediated neuroinflammation were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), western blot, RNA sequencing (RNA-seq), and immunofluorescence staining.

RESULTS

PKCδ levels were increased dramatically in the CSF of AD patients and positively correlated with cytokines. PKCδ is expressed mainly in microglia in the brain. Amyloid beta (Aβ) stimulation increased PKCδ expression and secretion, which led to upregulation of the nuclear factor kappa B (NF-κB) pathway and overproduction of proinflammatory cytokines. Downregulation or inhibition of PKCδ attenuated Aβ-induced microglial responses and improved cognitive function in an AD mouse model.

DISCUSSION

Our study identifies PKCδ as a potential biomarker and therapeutic target for microglia-mediated neuroinflammation in AD.

HIGHLIGHTS

Protein kinase C delta (PKCδ) levels increase in cerebrospinal fluid (CSF) of patients with Alzheimer's disease (AD), and positively correlate with elevated inflammatory cytokines in human subjects. PKCδ is expressed mainly in microglia in vivo, whereas amyloid beta (Aβ) stimulation increases PKCδ expression and secretion, causing upregulation of the nuclear factor kappa B (NF-κB) pathway and production of inflammatory cytokines. Downregulation or inhibition of PKCδ attenuates Aβ-enhanced NF-κB signaling and cytokine production in microglia and improves cognitive function in AD mice. PKCδ serves as a potential biomarker and therapeutic target for microglia-mediated neuroinflammation in AD.

Fluvoxamine maleate alleviates amyloid-beta load and neuroinflammation in 5XFAD mice to ameliorate Alzheimer disease pathology

Introduction

Alzheimer pathology (AD) is characterized by the deposition of amyloid beta (Aβ) and chronic neuroinflammation, with the NLRP3 inflammasome playing a significant role. This study demonstrated that the OCD drug fluvoxamine maleate (FXN) can potently ameliorate AD pathology in 5XFAD mice by promoting autophagy-mediated clearance of Aβ and inhibiting the NLRP3 inflammasome.

Methods

We used mice primary astrocytes to establish the mechanism of action of FXN against NLRP3 inflammasome by using various techniques like ELISA, Western blotting, confocal microscopy, Immunofluorescence, etc. The anti-AD activity of FXN was validated in transgenic 5XFAD mice following two months of treatment. This was followed by behavior analysis, examination of inflammatory and autophagy proteins and immunohistochemistry analysis for Aβ load in the hippocampi.

Results

Our data showed that FXN, at a low concentration of 78 nM, induces autophagy to inhibit NF-κB and the NLRP3 inflammasome, apart from directly inhibiting NLRP3 inflammasome in primary astrocytes. FXN activated the PRKAA2 pathway through CAMKK2 signaling, leading to autophagy induction. It inhibited the ATP-mediated NLRP3 inflammasome activation by promoting the autophagic degradation of NF-κB, resulting in the downregulation of pro-IL-1β and NLRP3. The anti-NLRP3 inflammasome effect of FXN was reversed when autophagy was inhibited by either genetic knockdown of the PRKAA2 pathway or pharmacological inhibition with bafilomycin A1. Furthermore, FXN treatment led to improved AD pathology in 5XFAD mice, resulting in significant improvements in various behavioral parameters such as working memory and neuromuscular coordination, making their behavior more similar to that of wild-type animals. FXN improved behavior in 5XFAD mice by clearing the Aβ deposits from the hippocampi and significantly reducing multiple inflammatory proteins, including NF-κB, GFAP, IBA1, IL-1β, TNF-α, and IL-6, which are associated with NF-κB and NLRP3 inflammasome in the brain. Moreover, these changes were accompanied by increased expression of autophagic proteins.

Discussion

Our data suggest that FXN ameliorates AD pathology, by simultaneously targeting two key pathological features: Aβ deposits and neuroinflammation. As an already approved drug, FXN holds potential as a candidate for human studies against AD.

Anti-Neuroinflammatory Effects of Ginkgo biloba Extract EGb 761 in LPS-Activated BV2 Microglial Cells

Inflammatory processes in the brain can exert important neuroprotective functions. However, in neurological and psychiatric disorders, it is often detrimental due to chronic microglial over-activation and the dysregulation of cytokines and chemokines. Growing evidence indicates the emerging yet prominent pathophysiological role of neuroinflammation in the development and progression of these disorders. Despite recent advances, there is still a pressing need for effective therapies, and targeting neuroinflammation is a promising approach. Therefore, in this study, we investigated the anti-neuroinflammatory potential of a marketed and quantified proprietary herbal extract of Ginkgo biloba leaves called EGb 761 (10-500 µg/mL) in BV2 microglial cells stimulated by LPS (10 ng/mL). Our results demonstrate significant inhibition of LPS-induced expression and release of cytokines tumor necrosis factor-α (TNF-α) and Interleukin 6 (IL-6) and chemokines C-X-C motif chemokine ligand 2 (CXCL2), CXCL10, c-c motif chemokine ligand 2 (CCL2) and CCL3 in BV2 microglial cells. The observed effects are possibly mediated by the mitogen-activated protein kinases (MAPK), p38 MAPK and ERK1/2, as well as the protein kinase C (PKC) and the nuclear factor (NF)-κB signaling cascades. The findings of this in vitro study highlight the anti-inflammatory properties of EGb 761 and its therapeutic potential, making it an emerging candidate for the treatment of neuroinflammatory diseases and warranting further research in pre-clinical and clinical settings.

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

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

Single-Cell RNA Sequencing Reveals Immunomodulatory Effects of Stem Cell Factor and Granulocyte Colony-Stimulating Factor Treatment in the Brains of Aged APP/PS1 Mice

Alzheimer's disease (AD) leads to progressive neurodegeneration and dementia. AD primarily affects older adults with neuropathological changes including amyloid-beta (Aβ) deposition, neuroinflammation, and neurodegeneration. We have previously demonstrated that systemic treatment with combined stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) (SCF+G-CSF) reduces the Aβ load, increases Aβ uptake by activated microglia and macrophages, reduces neuroinflammation, and restores dendrites and synapses in the brains of aged APPswe/PS1dE9 (APP/PS1) mice. However, the mechanisms underlying SCF+G-CSF-enhanced brain repair in aged APP/PS1 mice remain unclear. This study used a transcriptomic approach to identify the potential mechanisms by which SCF+G-CSF treatment modulates microglia and peripheral myeloid cells to mitigate AD pathology in the aged brain. After injections of SCF+G-CSF for 5 consecutive days, single-cell RNA sequencing was performed on CD11b+ cells isolated from the brains of 28-month-old APP/PS1 mice. The vast majority of cell clusters aligned with transcriptional profiles of microglia in various activation states. However, SCF+G-CSF treatment dramatically increased a cell population showing upregulation of marker genes related to peripheral myeloid cells. Flow cytometry data also revealed an SCF+G-CSF-induced increase of cerebral CD45high/CD11b+ active phagocytes. SCF+G-CSF treatment robustly increased the transcription of genes implicated in immune cell activation, including gene sets that regulate inflammatory processes and cell migration. The expression of S100a8 and S100a9 was robustly enhanced following SCF+G-CSF treatment in all CD11b+ cell clusters. Moreover, the topmost genes differentially expressed with SCF+G-CSF treatment were largely upregulated in S100a8/9-positive cells, suggesting a well-conserved transcriptional profile related to SCF+G-CSF treatment in resident and peripherally derived CD11b+ immune cells. This S100a8/9-associated transcriptional profile contained notable genes related to pro-inflammatory and anti-inflammatory responses, neuroprotection, and Aβ plaque inhibition or clearance. Altogether, this study reveals the immunomodulatory effects of SCF+G-CSF treatment in the aged brain with AD pathology, which will guide future studies to further uncover the therapeutic mechanisms.

Association between Skin Carotenoid Levels and Cognitive Impairment Screened by Mini-Cog in Patients with Glaucoma

Carotenoids, having strong antioxidant properties, have been associated with neurodegenerative conditions like dementia and glaucoma, characterized by neuronal loss leading to cognitive and visual dysfunction. Therefore, carotenoids have attracted attention as factors predictive of the onset and progression of these neurodegenerative diseases. However, the impact of carotenoids on cognitive impairment and glaucomatous visual field defects remains unexplored. We conducted a retrospective, observational clinical study to investigate the association between skin carotenoid (SC) levels and cognitive impairment, as screened by the Mini-Cog test, in glaucoma patients. The study included 406 participants and 812 eyes were examined (average age: 69.7 ± 11.4 years; 228 men, 178 women) with various types of glaucoma: primary open angle (57.6%), exfoliation (18.6%), and other types (23.8%). SC levels were estimated via pressure-mediated reflection spectroscopy. Mixed-effects regression models were utilized to examine the relationship between SC levels, visual field defects, and Mini-Cog results. Of the participants, 28 (6.9%) tested positive on the Mini-Cog, suggesting cognitive impairment. The average SC level in the Mini-Cog positive group was significantly lower than in the negative group (269.5 ± 86.4 A.U. vs. 329.2 ± 120.4 A.U., respectively; p = 0.01). Additionally, the visual field mean deviation (MD) in the Mini-Cog positive group was notably worse than that in the negative group (-19.64 ± 9.07 dB vs. -12.46 ± 9.28 dB, respectively; p < 0.0001). The mixed-effects regression analysis revealed a significant association between Mini-Cog positivity and lower SC levels (p = 0.0006), although SC levels did not significantly correlate with MD (p = 0.3). Our findings suggest that cognitive impairment in glaucoma patients is associated with lower SC levels, underscoring the potential benefits of maintaining carotenoid levels to slow cognitive function decline. The protective role of carotenoids in glaucoma merits further investigation.

An easy-to-perform method for microvessel isolation and primary brain endothelial cell culture to study Alzheimer's disease

Dysfunction of the blood-brain barrier (BBB) has been increasingly recognised as a critical early event in Alzheimer's disease (AD) pathophysiology. Central to this mechanism is the impaired function of brain endothelial cells (BECs), the primary structural constituents of the BBB, the study of which is imperative for understanding AD pathophysiology. However, the published methods to isolate BECs are time-consuming and have a low success rate. Here, we developed a rapid and streamlined protocol for BEC isolation without using transgenic reporters, flow cytometry, and magnetic beads, which are essential for existing methods. Using this novel protocol, we isolated high-purity BECs from cell clusters of cortical microvessels from wild-type and APPswe/PS1dE9 (APP/PS1, a classical AD model) mice at 2, 4 and 9 months of age. Reduced levels of tight junction proteins Claudin-5 and Zonula Occludens-1, as well as glucose transporter 1, were observed in the isolated cortical microvessels from APP/PS1 mice and amyloid-β (Aβ) oligomer-treated BECs from wild-type mice. Trans-well permeability assay showed increased FITC-dextran leakage in BECs treated with Aβ, suggesting impaired BBB permeability. BECs obtained using our novel protocol can undergo various experimental analyses, including immunofluorescence staining, western blotting, real-time PCR, and trans-well permeability assay. In conclusion, our novel protocol represents a reliable and valuable tool for in vitro modelling BBB to study AD-related mechanisms and develop targeted therapeutic strategies.

Unveiling the Complex Role of Exosomes in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative illness, characterized by memory loss and cognitive decline, accounting for 60-80% of dementia cases. AD is characterized by senile plaques made up of amyloid β (Aβ) protein, intracellular neurofibrillary tangles caused by hyperphosphorylation of tau protein linked with microtubules, and neuronal loss. Currently, therapeutic treatments and nanotechnological developments are effective in treating the symptoms of AD, but a cure for the illness has not yet been found. Recently, the increased study of extracellular vesicles (EVs) has led to a growing awareness of their significant involvement in neurodegenerative disorders, including AD. Exosomes are small extracellular vesicles that transport various components including messenger RNAs, non-coding RNAs, proteins, lipids, DNA, and other bioactive compounds from one cell to another, facilitating information transmission and material movement. There is growing evidence indicating that exosomes have complex functions in AD. Exosomes may have a dual role in Alzheimer's disease by contributing to neuronal death and also helping to alleviate the pathological progression of the disease. Therefore, the primary aim of this review is to outline the updated understandings on exosomes biogenesis and many functions of exosomes in the generation, conveyance, distribution, and elimination of hazardous proteins related to Alzheimer's disease. This review is intended to provide novel insights for understanding the development, specific treatment, and early detection of Alzheimer's disease.

Single cell RNA sequencing reveals immunomodulatory effects of stem cell factor and granulocyte colony-stimulating factor treatment in the brains of aged APP/PS1 mice

Alzheimers disease leads to progressive neurodegeneration and dementia. Alzheimers disease primarily affects older adults with neuropathological changes including amyloid beta deposition, neuroinflammation, and neurodegeneration. We have previously demonstrated that systemic treatment with combined stem cell factor, SCF, and granulocyte colony stimulating factor, GCSF, reduces amyloid beta load, increases amyloid beta uptake by activated microglia and macrophages, reduces neuroinflammation, and restores dendrites and synapses in the brains of aged APP-PS1 mice. However, the mechanisms underlying SCF-GCSF-enhanced brain repair in aged APP-PS1 mice remain unclear. This study used a transcriptomic approach to identify potential mechanisms by which SCF-GCSF treatment modulates microglia and peripheral myeloid cells to mitigate Alzheimers disease pathology in the aged brain. After injections of SCF-GCSF for 5 consecutive days, single cell RNA sequencing was performed on CD11b positive cells isolated from the brains of 28-month-old APP-PS1 mice. The vast majority of cell clusters aligned with transcriptional profiles of microglia in various activation states. However, SCF-GCSF treatment dramatically increased a cell population showing upregulation of marker genes related to peripheral myeloid cells. Flow cytometry data also revealed an SCF-GCSF-induced increase of cerebral CD45high-CD11b positive active phagocytes. SCF-GCSF treatment robustly increased the transcription of genes implicated in immune cell activation, including gene sets that regulate inflammatory processes and cell migration. Expression of S100a8 and S100a9 were robustly enhanced following SCF-GCSF treatment in all CD11b positive cell clusters. Moreover, the topmost genes differentially expressed with SCF-GCSF treatment were largely upregulated in S100a8-S100a9 positive cells, suggesting a well-conserved transcriptional profile related to SCF-GCSF treatment in resident and peripherally derived CD11b positive immune cells. This S100a8-S100a9-associated transcriptional profile contained notable genes related to proinflammatory and antiinflammatory responses, neuroprotection, and amyloid beta plaque inhibition or clearance. Altogether, this study reveals immunomodulatory effects of SCF-GCSF treatment in the aged brain with Alzheimers disease pathology, which will guide future studies to further uncover the therapeutic mechanisms.

Study on multi-target effects of the novel HDAC6 inhibitor W5 on Aβ/Cu2+-induced Alzheimer's disease model of rats

Histone deacetylase 6 (HDAC6) is a key therapeutic target in neurodegenerative diseases such as Alzheimer's disease (AD), which has been demonstrated to play an essential role in memory function and microtubule-associated tau physiology. In this study, W5 was used to treat AD model rats induced by Aβ/Cu2+ to study the improving effect of W5 on learning and memory impairment in AD rats and its related mechanism, to provide the basis for the subsequent development of W5 as an anti-AD drug. Results showed that W5 could decrease the expression of Aβ, Tau, and p-Tau proteins in the hippocampus of AD rats to inhibit the formation of senile plaques and neurofibrillary tangles, down-regulate the expression of Bax mRNA and Caspase-3 mRNA, and up-regulate the expression of Bcl-2 mRNA to reduce the apoptosis of neuron cells, reverse the expression of TNF-α, IL-1β and IL-6 mRNA to regulate neuroinflammatory response in AD rat brain. W5 also could regulate the oxidative stress state of AD rats, and balance the neurotransmitter disorder in AD rats' brain tissue. Overall, W5 could recover the morphology of hippocampal neurons and improve the learning and memory dysfunction in AD rats by regulating multiple targets in AD rats, providing a promising therapeutic avenue for the treatment of AD.

Human C15orf39 Inhibits Inflammatory Response via PRMT2 in Human Microglial HMC3 Cell Line

Microglia-mediated inflammatory response is one key cause of many central nervous system diseases, like Alzheimer's disease. We hypothesized that a novel C15orf39 (MAPK1 substrate) plays a critical role in the microglial inflammatory response. To confirm this hypothesis, we used lipopolysaccharide (LPS)-and interferon-gamma (IFN-γ)-induced human microglia HMC3 cells as a representative indicator of the microglial in vitro inflammatory response. We found that C15orf39 was down-regulated when interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα) expression increased in LPS/IFN-γ-stimulated HMC3 cells. Once C15orf39 was overexpressed, IL-6 and TNFα expression were reduced in LPS/IFN-γ-stimulated HMC3 cells. In contrast, C15orf39 knockdown promoted IL-6 and TNFα expression in LPS/IFN-γ-stimulated HMC3 cells. These results suggest that C15orf39 is a suppressive factor in the microglial inflammatory response. Mechanistically, C15orf39 interacts with the cytoplasmic protein arginine methyltransferase 2 (PRMT2). Thus, we termed C15orf39 a PRMT2 interaction protein (PRMT2 IP). Furthermore, the interaction of C15orf39 and PRMT2 suppressed the activation of NF-κB signaling via the PRMT2-IκBα signaling axis, which then led to a reduction in transcription of the inflammatory factors IL6 and TNF-α. Under inflammatory conditions, NF-κBp65 was found to be activated and to suppress C15orf39 promoter activation, after which it canceled the suppressive effect of the C15orf39-PRMT2-IκBα signaling axis on IL-6 and TNFα transcriptional expression. In conclusion, our findings demonstrate that in a steady condition, the interaction of C15orf39 and PRMT2 stabilizes IκBα to inhibit IL-6 and TNFα expression by suppressing NF-κB signaling, which reversely suppresses C15orf39 transcription to enhance IL-6 and TNFα expression in the microglial inflammatory condition. Our study provides a clue as to the role of C15orf39 in microglia-mediated inflammation, suggesting the potential therapeutic efficacy of C15orf39 in some central nervous system diseases.

Chronic Astrocytic TNFα Production in the Preoptic-Basal Forebrain Causes Aging-like Sleep-Wake Disturbances in Young Mice

Sleep disruption is a frequent problem of advancing age, often accompanied by low-grade chronic central and peripheral inflammation. We examined whether chronic neuroinflammation in the preoptic and basal forebrain area (POA-BF), a critical sleep-wake regulatory structure, contributes to this disruption. We developed a targeted viral vector designed to overexpress tumor necrosis factor-alpha (TNFα), specifically in astrocytes (AAV5-GFAP-TNFα-mCherry), and injected it into the POA of young mice to induce heightened neuroinflammation within the POA-BF. Compared to the control (treated with AAV5-GFAP-mCherry), mice with astrocytic TNFα overproduction within the POA-BF exhibited signs of increased microglia activation, indicating a heightened local inflammatory milieu. These mice also exhibited aging-like changes in sleep-wake organization and physical performance, including (a) impaired sleep-wake functions characterized by disruptions in sleep and waking during light and dark phases, respectively, and a reduced ability to compensate for sleep loss; (b) dysfunctional VLPO sleep-active neurons, indicated by fewer neurons expressing c-fos after suvorexant-induced sleep; and (c) compromised physical performance as demonstrated by a decline in grip strength. These findings suggest that inflammation-induced dysfunction of sleep- and wake-regulatory mechanisms within the POA-BF may be a critical component of sleep-wake disturbances in aging.

Selected cannabis cultivars modulate glial activation: in vitro and in vivo studies

INTRODUCTION

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system characterized by neuroinflammation, demyelination and axonal loss. Cannabis, an immunomodulating agent, is known for its ability to treat MS effectively. However, due to variations in the profile of secondary metabolites, especially cannabinoids, among cannabis cultivars, the effectiveness of cannabis treatment can vary, with significant variability in the effects on different biological parameters. For screening available cultivars, cellular in vitro as well as pre-clinical in vivo assays, are required to evaluate the effectiveness of the wide range of chemical variability that exists in cannabis cultivars. This study evaluated comparatively three chemically diverse cannabis cultivars, CN2, CN4 and CN6, containing different ratios of phytocannabinoids, for their neuroinflammatory activity in MS model.

MATERIALS AND METHODS

In vitro experiments were performed with lipopolysaccharide (LPS)-activated BV-2 microglia and primary glial cells to evaluate the effect of different cannabis cultivars on nitric oxide (NO) and inflammatory cytokines, as well as inducible nitric oxide synthase (iNOS) protein expression. An in vivo experiment using the experimental autoimmune encephalomyelitis (EAE) MS model was conducted using Myelin oligodendrocyte glycoprotein (MOG) as the activating peptide. The cannabis extracts of the cultivars CN2, CN4, CN6 or vehicle, were intraperitoneally injected with clinical scores given based on observed symptoms over the course of study. At the end of the experiment, the mice were sacrificed, and splenocyte cytokine secretion was measured using ELISA. Lumbar sections from the spinal cord of treated MS mice were evaluated for microglia, astrocytes and CD4+ cells.

RESULTS

Extracts of the CN2 cultivar contained tetrahydrocannabinolic acid (THCA) and tetrahydrocannabinol (THC) without cannabidiol (CBD), and a number of monoterpenes. CN4 contained cannabidiolic acid (CBDA) and tetrahydrocannabidiolic acid (THCA), with significant amounts of THC: CBD in a 1:1 ratio, as well as sesquiterpenes and some monoterpenes; and CN6 contained primarily CBDA and THCA, as well as THC and CBD in a 2:1 ratio, with some sesquiterpenes and no monoterpenes. All extracts were not cytotoxic in glial cells up to 50 µg/ml. Dose dependent inhibition of LPS-induced BV2 as well as primary microglial NO secretion confirmed the anti-inflammatory and anti-oxidative activity of the three cannabis cultivars. CN2 but not CN4 reduced both astrocytosis and microglial activation in lumbar sections of EAE mice. In contrast, CN4 but not CN2 significantly decreased the secretion of TNFα and Interferon γ (IFNγ) in primary splenocytes extracted from EAE mice.

CONCLUSIONS

While both cannabis cultivars, CN2 and CN4, significantly reduced the severity of the clinical signs throughout the course of the study, they modulated different inflammatory mediators and pathways, probably due to differences in their phytocannabinoid composition. This demonstrates the differential potential of cannabis cultivars differing in chemotype to regulate neuroinflammation and their potential to treat MS.

Characterizing dysregulations via cell-cell communications in Alzheimer's brains using single-cell transcriptomes

BACKGROUND

Alzheimer's disease (AD) is a devastating neurodegenerative disorder affecting 44 million people worldwide, leading to cognitive decline, memory loss, and significant impairment in daily functioning. The recent single-cell sequencing technology has revolutionized genetic and genomic resolution by enabling scientists to explore the diversity of gene expression patterns at the finest resolution. Most existing studies have solely focused on molecular perturbations within each cell, but cells live in microenvironments rather than in isolated entities. Here, we leveraged the large-scale and publicly available single-nucleus RNA sequencing in the human prefrontal cortex to investigate cell-to-cell communication in healthy brains and their perturbations in AD. We uniformly processed the snRNA-seq with strict QCs and labeled canonical cell types consistent with the definitions from the BRAIN Initiative Cell Census Network. From ligand and receptor gene expression, we built a high-confidence cell-to-cell communication network to investigate signaling differences between AD and healthy brains.

RESULTS

Specifically, we first performed broad communication pattern analyses to highlight that biologically related cell types in normal brains rely on largely overlapping signaling networks and that the AD brain exhibits the irregular inter-mixing of cell types and signaling pathways. Secondly, we performed a more focused cell-type-centric analysis and found that excitatory neurons in AD have significantly increased their communications to inhibitory neurons, while inhibitory neurons and other non-neuronal cells globally decreased theirs to all cells. Then, we delved deeper with a signaling-centric view, showing that canonical signaling pathways CSF, TGFβ, and CX3C are significantly dysregulated in their signaling to the cell type microglia/PVM and from endothelial to neuronal cells for the WNT pathway. Finally, after extracting 23 known AD risk genes, our intracellular communication analysis revealed a strong connection of extracellular ligand genes APP, APOE, and PSEN1 to intracellular AD risk genes TREM2, ABCA1, and APP in the communication from astrocytes and microglia to neurons.

CONCLUSIONS

In summary, with the novel advances in single-cell sequencing technologies, we show that cellular signaling is regulated in a cell-type-specific manner and that improper regulation of extracellular signaling genes is linked to intracellular risk genes, giving the mechanistic intra- and inter-cellular picture of AD.

Chlamydia pneumoniae in Alzheimer's disease pathology

While recent advances in diagnostics and therapeutics offer promising new approaches for Alzheimer's disease (AD) diagnosis and treatment, there is still an unmet need for an effective remedy, suggesting new avenues of research are required. Besides many plausible etiologies for AD pathogenesis, mounting evidence supports a possible role for microbial infections. Various microbes have been identified in the postmortem brain tissues of human AD patients. Among bacterial pathogens in AD, Chlamydia pneumoniae (Cp) has been well characterized in human AD brains and is a leading candidate for an infectious involvement. However, no definitive studies have been performed proving or disproving Cp's role as a causative or accelerating agent in AD pathology and cognitive decline. In this review, we discuss recent updates for the role of Cp in human AD brains as well as experimental models of AD. Furthermore, based on the current literature, we have compiled a list of potential mechanistic pathways which may connect Cp with AD pathology.