3-Hydroxyanthranilic Acid Delays Paralysis in Caenorhabditis elegans Models of Amyloid-Beta and Polyglutamine Proteotoxicity.

Age is the primary risk factor for neurodegenerative diseases such as Alzheimer's and Huntington's disease. Alzheimer's disease is the most common form of dementia and a leading cause of death in the elderly population of the United States. No effective treatments for these diseases currently exist. Identifying effective treatments for Alzheimer's, Huntington's, and other neurodegenerative diseases is a major current focus of national scientific resources, and there is a critical need for novel therapeutic strategies. Here, we investigate the potential for targeting the kynurenine pathway metabolite 3-hydroxyanthranilic acid (3HAA) using Caenorhabditis elegans expressing amyloid-beta or a polyglutamine peptide in body wall muscle, modeling the proteotoxicity in Alzheimer's and Huntington's disease, respectively. We show that knocking down the enzyme that degrades 3HAA, 3HAA dioxygenase (HAAO), delays the age-associated paralysis in both models. This effect on paralysis was independent of the protein aggregation in the polyglutamine model. We also show that the mechanism of protection against proteotoxicity from HAAO knockdown is mimicked by 3HAA supplementation, supporting elevated 3HAA as the mediating event linking HAAO knockdown to delayed paralysis. This work demonstrates the potential for 3HAA as a targeted therapeutic in neurodegenerative disease, though the mechanism is yet to be explored.

Transcriptomic analysis reveals sex-specific patterns in the hippocampus in Alzheimer's disease.

Background: The hippocampus, vital for memory and learning, is among the first brain regions affected in Alzheimer's Disease (AD) and exhibits adult neurogenesis. Women face twice the risk of developing AD compare to men, making it crucial to understand sex differences in hippocampal function for comprehending AD susceptibility. Methods: We conducted a comprehensive analysis of bulk mRNA postmortem samples from the whole hippocampus (GSE48350, GSE5281) and its CA1 and CA3 subfields (GSE29378). Our aim was to perform a comparative molecular signatures analysis, investigating sex-specific differences and similarities in the hippocampus and its subfields in AD. This involved comparing the gene expression profiles among: (a) male controls (M-controls) vs. female controls (F-controls), (b) females with AD (F-AD) vs. F-controls, (c) males with AD (M-AD) vs. M-controls, and (d) M-AD vs. F-AD. Furthermore, we identified AD susceptibility genes interacting with key targets of menopause hormone replacement drugs, specifically the ESR1 and ESR2 genes, along with GPER1. Results: The hippocampal analysis revealed contrasting patterns between M-AD vs. M-controls and F-AD vs. F-controls, as well as M-controls vs. F-controls. Notably, BACE1, a key enzyme linked to amyloid-beta production in AD pathology, was found to be upregulated in M-controls compared to F-controls in both CA1 and CA3 hippocampal subfields. In M-AD vs. M-controls, the GABAergic synapse was downregulated, and the Estrogen signaling pathway was upregulated in both subfields, unlike in F-AD vs. F-controls. Analysis of the whole hippocampus also revealed upregulation of the GABAergic synapse in F-AD vs. F-controls. While direct comparison of M-AD vs. F-AD, revealed a small upregulation of the ESR1 gene in the CA1 subfield of males. Conversely, F-AD vs. F-controls exhibited downregulation of the Dopaminergic synapse in both subfields, while the Calcium signaling pathway showed mixed regulation, being upregulated in CA1 but downregulated in CA3, unlike in M-AD vs. M-controls. The upregulated Estrogen signaling pathway in M-AD, suggests a compensatory response to neurodegenerative specifically in males with AD. Our results also identified potential susceptibility genes interacting with ESR1 and ESR2, including MAPK1, IGF1, AKT1, TP53 and CD44. Conclusion: These findings underscore the importance of sex-specific disease mechanisms in AD pathogenesis. Region-specific analysis offers a more detailed examination of localized changes in the hippocampus, enabling to capture sex-specific molecular patterns in AD susceptibility and progression.

A novel APP splice variant-dependent marker system to precisely demarcate maturity in SH-SY5Y cell-derived neurons.

SH-SY5Y, a neuroblastoma cell line, can be converted into mature neuronal phenotypes, characterized by the expression of mature neuronal and neurotransmitter markers. However, the mature phenotypes described across multiple studies appear inconsistent. As this cell line expresses common neuronal markers after a simple induction, there is a high chance of misinterpreting its maturity. Therefore, sole reliance on common neuronal markers is presumably inadequate. The Alzheimer's disease (AD) central gene, amyloid precursor protein (APP), has shown contrasting transcript variant dynamics in various cell types. We differentiated SH-SY5Y cells into mature neuron-like cells using a concise protocol and observed the upregulation of total APP throughout differentiation. However, APP transcript variant-1 was upregulated only during the early to middle stages of differentiation and declined in later stages. We identified the maturity state where this post-transcriptional shift occurs, terming it "true maturity." At this stage, we observed a predominant expression of mature neuronal and cholinergic markers, along with a distinct APP variant pattern. Our findings emphasize the necessity of using a differentiation state-sensitive marker system to precisely characterize SH-SY5Y differentiation. Moreover, this study offers an APP-guided, alternative neuronal marker system to enhance the accuracy of the conventional markers.

Blood biomarkers of neurodegeneration associate differently with amyloid deposition, medial temporal atrophy, and cerebrovascular changes in APOE ε4-enriched cognitively unimpaired elderly.

BACKGROUND: Alzheimer's disease (AD) is characterized by the accumulation of amyloid-ß (Aß) plaques, neurofibrillary tau tangles, and neurodegeneration in the brain parenchyma. Here, we aimed to (i) assess differences in blood and imaging biomarkers used to evaluate neurodegeneration among cognitively unimpaired APOE ε4 homozygotes, heterozygotes, and non-carriers with varying risk for sporadic AD, and (ii) to determine how different cerebral pathologies (i.e., Aß deposition, medial temporal atrophy, and cerebrovascular pathology) contribute to blood biomarker concentrations in this sample. METHODS: Sixty APOE ε4 homozygotes (n = 19), heterozygotes (n = 21), and non-carriers (n = 20) ranging from 60 to 75 years, were recruited in collaboration with Auria biobank (Turku, Finland). Participants underwent Aß-PET ([11C]PiB), structural brain MRI including T1-weighted and T2-FLAIR sequences, and blood sampling for measuring serum neurofilament light chain (NfL), plasma total tau (t-tau), plasma N-terminal tau fragments (NTA-tau) and plasma glial fibrillary acidic protein (GFAP). [11C]PiB standardized uptake value ratio was calculated for regions typical for Aß accumulation in AD. MRI images were analysed for regional volumes, atrophy scores, and volumes of white matter hyperintensities. Differences in biomarker levels and associations between blood and imaging biomarkers were tested using uni- and multivariable linear models (unadjusted and adjusted for age and sex). RESULTS: Serum NfL concentration was increased in APOE ε4 homozygotes compared with non-carriers (mean 21.4 pg/ml (SD 9.5) vs. 15.5 pg/ml (3.8), p = 0.013), whereas other blood biomarkers did not differ between the groups (p > 0.077 for all). From imaging biomarkers, hippocampal volume was significantly decreased in APOE ε4 homozygotes compared with non-carriers (6.71 ml (0.86) vs. 7.2 ml (0.7), p = 0.029). In the whole sample, blood biomarker levels were differently predicted by the three measured cerebral pathologies; serum NfL concentration was associated with cerebrovascular pathology and medial temporal atrophy, while plasma NTA-tau associated with medial temporal atrophy. Plasma GFAP showed significant association with both medial temporal atrophy and Aß pathology. Plasma t-tau concentration did not associate with any of the measured pathologies. CONCLUSIONS: Only increased serum NfL concentrations and decreased hippocampal volume was observed in cognitively unimpaired APOEε4 homozygotes compared to non-carriers. In the whole population the concentrations of blood biomarkers were affected in distinct ways by different pathologies.

Electropositive Citric Acid-Polyethyleneimine Carbon Dots Carrying the PINK1 Gene Regulate ATP-Related Metabolic Dysfunction in APP/PS1-N2a Cells.

(1) Background: Alzheimer's disease (AD) is characterized by ß-amyloid (Aß) peptide accumulation and mitochondrial dysfunction during the early stage of disease. PINK1 regulates the balance between mitochondrial homeostasis and bioenergy supply and demand via the PINK1/Parkin pathway, Na+/Ca2+ exchange, and other pathways. (2) Methods: In this study, we synthesized positively charged carbon dots (CA-PEI CDs) using citric acid (CA) and polyethyleneimine (PEI) and used them as vectors to express PINK1 genes in the APP/PS1-N2a cell line to determine mitochondrial function, electron transport chain (ETC) activity, and ATP-related metabolomics. (3) Results: Our findings showed that the CA-PEI CDs exhibit the characteristics of photoluminescence, low toxicity, and concentrated DNA. They are ideal biological carriers for gene delivery. PINK1 overexpression significantly increased the mitochondrial membrane potential in APP/PS1-N2a cells and reduced reactive-oxygen-species generation and Aß1-40 and Aß1-42 levels. An increase in the activity of NADH ubiquinone oxidoreductase (complex I, CI) and cytochrome C oxidase (complex IV, CIV) induces the oxidative phosphorylation of mitochondria, increasing ATP generation. (4) Conclusions: These findings indicate that the PINK gene can alleviate AD by increasing bioenergetic metabolism, reducing Aß1-40 and Aß1-42, and increasing ATP production.

Effects of SPI1-mediated transcriptome remodeling on Alzheimer's disease-related phenotypes in mouse models of Aß amyloidosis.

SPI1 was recently reported as a genetic risk factor for Alzheimer's disease (AD) in large-scale genome-wide association studies. However, it is unknown whether SPI1 should be downregulated or increased to have therapeutic benefits. To investigate the effect of modulating SPI1 levels on AD pathogenesis, we performed extensive biochemical, histological, and transcriptomic analyses using both Spi1-knockdown and Spi1-overexpression mouse models. Here, we show that the knockdown of Spi1 expression significantly exacerbates insoluble amyloid-ß (Aß) levels, amyloid plaque deposition, and gliosis. Conversely, overexpression of Spi1 significantly ameliorates these phenotypes and dystrophic neurites. Further mechanistic studies using targeted and single-cell transcriptomics approaches demonstrate that altered Spi1 expression modulates several pathways, such as immune response pathways and complement system. Our data suggest that transcriptional reprogramming by targeting transcription factors, like Spi1, might hold promise as a therapeutic strategy. This approach could potentially expand the current landscape of druggable targets for AD.

Estradiol improves behavior in FAD transgenic mice that express APOE3 but not APOE4 after ovariectomy.

Increasing evidence suggests that female individuals have a higher Alzheimer's disease (AD) risk associated with post-menopausal loss of circulating estradiol (E2). However, clinical data are conflicting on whether E2 lowers AD risk. One potential contributing factor is APOE. The greatest genetic risk factor for AD is APOE4, a factor that is pronounced in female individuals post-menopause. Clinical data suggests that APOE impacts the response of AD patients to E2 replacement therapy. However, whether APOE4 prevents, is neutral, or promotes any positive effects of E2 is unclear. Therefore, our goal was to determine whether APOE modulates the impact of E2 on behavior and AD pathology in vivo. To that end, mice that express human APOE3 (E3FAD) or APOE4 (E4FAD) and overproduce Aß42 were ovariectomized at either 4 months (early) or 8 months (late) and treated with vehicle or E2 for 4 months. In E3FAD mice, we found that E2 mitigated the detrimental effect of ovariectomy on memory, with no effect on Aß in the early paradigm and only improved learning in the late paradigm. Although E2 lowered Aß in E4FAD mice in the early paradigm, there was no impact on learning or memory, possibly due to higher Aß pathology compared to E3FAD mice. In the late paradigm, there was no effect on learning/memory and Aß pathology in E4FAD mice. Collectively, these data support the idea that, in the presence of Aß pathology, APOE impacts the response to E2 supplementation post-menopause.

G-protein coupled estrogen receptor 1, amyloid-ß, and tau tangles in older adults.

Accumulation of amyloid-ß (Aß) and tau tangles are hallmarks of Alzheimer's disease. Aß is extracellular while tau tangles are typically intracellular, and it is unknown how these two proteinopathies are connected. Here, we use data of 1206 elders and test that RNA expression levels of GPER1, a transmembrane protein, modify the association of Aß with tau tangles. GPER1 RNA expression is related to more tau tangles (p = 0.001). Moreover, GPER1 expression modifies the association of immunohistochemistry-derived Aß load with tau tangles (p = 0.044). Similarly, GPER1 expression modifies the association between Aß proteoforms and tau tangles: total Aß protein (p = 0.030) and Aß38 peptide (p = 0.002). Using single nuclei RNA-seq indicates that GPER1 RNA expression in astrocytes modifies the relation of Aß load with tau tangles (p = 0.002), but not GPER1 in excitatory neurons or endothelial cells. We conclude that GPER1 may be a link between Aß and tau tangles driven mainly by astrocytic GPER1 expression.

Differential disruptions in population coding along the dorsal-ventral axis of CA1 in the APP/PS1 mouse model of Aß pathology.

Alzheimer's Disease (AD) is characterized by a range of behavioral alterations, including memory loss and psychiatric symptoms. While there is evidence that molecular pathologies, such as amyloid beta (Aß), contribute to AD, it remains unclear how this histopathology gives rise to such disparate behavioral deficits. One hypothesis is that Aß exerts differential effects on neuronal circuits across brain regions, depending on the neurophysiology and connectivity of different areas. To test this, we recorded from large neuronal populations in dorsal CA1 (dCA1) and ventral CA1 (vCA1), two hippocampal areas known to be structurally and functionally diverse, in the APP/PS1 mouse model of amyloidosis. Despite similar levels of Aß pathology, dCA1 and vCA1 showed distinct disruptions in neuronal population activity as animals navigated a virtual reality environment. In dCA1, pairwise correlations and entropy, a measure of the diversity of activity patterns, were decreased in APP/PS1 mice relative to age-matched C57BL/6 controls. However, in vCA1, APP/PS1 mice had increased pair-wise correlations and entropy as compared to age matched controls. Finally, using maximum entropy models, we connected the microscopic features of population activity (correlations) to the macroscopic features of the population code (entropy). We found that the models' performance increased in predicting dCA1 activity, but decreased in predicting vCA1 activity, in APP/PS1 mice relative to the controls. Taken together, we found that Aß exerts distinct effects across different hippocampal regions, suggesting that the various behavioral deficits of AD may reflect underlying heterogeneities in neuronal circuits and the different disruptions that Aß pathology causes in those circuits.

Sildenafil Reverses the Neuropathological Alzheimer's Disease Phenotype in Cholinergic-Like Neurons Carrying the Presenilin 1 E280A Mutation.

Background: Familial Alzheimer's disease (FAD) presenilin 1 E280A (PSEN 1 E280A) is characterized by functional impairment and the death of cholinergic neurons as a consequence of amyloid-ß (Aß) accumulation and abnormal phosphorylation of the tau protein. Currently, there are no available therapies that can cure FAD. Therefore, new therapies are urgently needed for treating this disease. Objective: To assess the effect of sildenafil (SIL) on cholinergic-like neurons (ChLNs) harboring the PSEN 1 E280A mutation. Methods: Wild-type (WT) and PSEN 1 E280A ChLNs were cultured in the presence of SIL (25µM) for 24 h. Afterward, proteinopathy, cell signaling, and apoptosis markers were evaluated via flow cytometry and fluorescence microscopy. Results: We found that SIL was innocuous toward WT PSEN 1 ChLNs but reduced the accumulation of intracellular Aß fragments by 87%, decreased the non-physiological phosphorylation of the protein tau at residue Ser202/Thr205 by 35%, reduced the phosphorylation of the proapoptotic transcription factor c-JUN at residue Ser63/Ser73 by 63%, decreased oxidized DJ-1 at Cys106-SO3 by 32%, and downregulated transcription factor TP53 (tumor protein p53), BH-3-only protein PUMA (p53 upregulated modulator of apoptosis), and cleaved caspase 3 (CC3) expression by 20%, 32%, and 22%, respectively, compared with untreated mutant ChLNs. Interestingly, SIL also ameliorated the dysregulation of acetylcholine-induced calcium ion (Ca2+) influx in PSEN 1 E280A ChLNs. Conclusions: Although SIL showed no antioxidant capacity in the oxygen radical absorbance capacity and ferric ion reducing antioxidant power assays, it might function as an anti-amyloid and antiapoptotic agent and functional neuronal enhancer in PSEN 1 E280A ChLNs. Therefore, the SIL has therapeutic potential for treating FAD.

Downregulation of miR-181c-5p in Alzheimer's disease weakens the response of microglia to Aß phagocytosis.

Alzheimer's disease (AD) is an age-associated neurodegenerative disease. Recently, studies have demonstrated the potential involvement of microRNA-181c-5p (miR-181c-5p) in AD. However, the mechanism through which miR-181c-5p is responsible for the onset and progression of this disease remains unclear, and our study aimed to explore this problem. Differential expression analysis of the AD dataset was performed to identify dysregulated genes. Based on hypergeometric analysis, AD differential the upstream regulation genes miR-181c-5p was found. We constructed a model where SH-SY5Y and BV2 cells were exposed to Aß1-42 to simulate AD. Levels of tumor necrosis factor-alpha, interleukin-6, and IL-1ß were determined using enzyme-linked immunosorbent assay or reverse transcription quantitative polymerase chain reaction. Phosphorylation levels of p-P38 and P38 were detected by Western blot. The level of apoptosis in BV2 cells under Aß1-42 stress was exacerbated by miR-181c-5p mimic. Downregulated miR-181c-5p impaired the phagocytosis and degradation of Aß by BV2 cells. The release of proinflammatory cytokines in BV2 cells with Aß1-42 stress was alleviated by miR-181c-5p upregulation. Additionally, miR-181c-5p downregulation alleviated the phosphorylation of P38 in Aß1-42-induced SH-SY5Y cells. In conclusion, miR-181c-5p improves the phagocytosis of Aß by microglial cells in AD patients, thereby reducing neuroinflammation.

[Effect of Huanglian Jiedu Decoction on TREM2/Akt/GSK3ß pathway in cerebral cortex of APP/PS1 transgenic mice].

The Chinese medical mechanism of Huanglian Jieduo Decoction on treating Alzheimer's disease(AD) characterized by "toxin damaging brain collateral" is still unclear. This study aims to explore the mechanism of Huanglian Jieduo Decoction on regulating triggering receptor expressed on myeloid cells 2(TREM2)/protein kinase B(Akt)/glycogen synthase kinase 3ß(GSK3ß) pathway to improve the cognitive deficit in APP/PS1 transgenic mice. APP/PS1 mice of approximately nine months old were randomly divided into the model group, the low, medium, and high(2.5, 5, and 10 g·kg~(-1)) groups of Huanglian Jiedu Decoction, and 0.75 mg·kg~(-1) donepezil hydrochloride group, and the C57BL/6J mice with the same age were taken as the normal group. After one month of continuous oral administration, a Morris water maze was performed to detect the learning and memory ability of mice. Hematoxylin-eosin(HE) staining was applied to observe the morphology of neuronal cells in the cortical area of mice. Immunofluorescence was used to detect the protein expressions of ß-amyloid(Aß_(1-42)), CD86, and arginase 1(Arg1). The mRNA levels of interleukin(IL)-1ß, IL-6, and IL-10 in the cortex of mice were detected by real-time fluorescence quantitative polymerase chain reaction(RT-qPCR). The protein expressions of TREM2, phosphoinositide-3 kinase(PI3K), Akt, GSK3ß, and beta-catenin(ß-catenin) in mouse cortex were determined by Western blot. The results indicated that the escape latency of the model group was significantly prolonged, and the residence time in the target quadrant and the number of crossing the platform were significantly reduced compared with the normal group. Mice in the model group had a significantly lower number of neurons in the cortex and showed nuclear pyknosis and a significant increase in the expressions of Aß_(1-42) and CD86. The mRNA levels of IL-1ß and IL-6 in tissue were significantly increased, IL-10 were increased, while Arg1 were significantly decreased. The expression of TREM2, p-PI3K(Y607), p-Akt(T308), p-GSK3ß(Ser9), and ß-catenin in the cortex were significantly down-regulated. Compared with the model group, the escape latency of the mice in the administration group was significantly shortened, and the number of crossing the platform and the residence time in the target quadrant were significantly increased. Furthermore, the number of neurons in the cortex of mice was increased, and nuclear pyknosis was improved. Aß_(1-42) deposition was decreased significantly. The mRNA levels of IL-1ß, IL-6 and CD86 were significantly decreased, while IL-10 and Arg1 levels were significantly increased. The expression of TREM2, p-PI3K(Y607), p-Akt(T308), p-GSK3ß(Ser9), and ß-catenin protein in the cortex of each administration group was significantly up-regulated compared with the model group. In conclusion, Huanglian Jiedu Decoction reduced the expression of Aß_(1-42) and neuroinflammation to a neuro-protective effect, thereby improving the learning and memory ability in APP/PS1 mice, which may be related to the TREM2/Akt/GSK3ß signaling pathway.

Histone deacetylase-3 regulates the expression of the amyloid precursor protein and its inhibition promotes neuroregenerative pathways in Alzheimer's disease models.

HDAC3 inhibition has been shown to improve memory and reduce amyloid-ß (Aß) in Alzheimer's disease (AD) models, but the underlying mechanisms are unclear. We investigated the molecular effects of HDAC3 inhibition on AD pathology, using in vitro and ex vivo models of AD, based on our finding that HDAC3 expression is increased in AD brains. For this purpose, N2a mouse neuroblastoma cells as well as organotypic brain cultures (OBCSs) of 5XFAD and wild-type mice were incubated with various concentrations of the HDAC3 selective inhibitor RGFP966 (0.1-10 µM) for 24 h. Treatment with RGFP966 or HDAC3 knockdown in N2a cells was associated with an increase on amyloid precursor protein (APP) and mRNA expressions, without alterations in Aß42 secretion. In vitro chromatin immunoprecipitation analysis revealed enriched HDAC3 binding at APP promoter regions. The increase in APP expression was also detected in OBCSs from 5XFAD mice incubated with 1 µM RGFP966, without changes in Aß. In addition, HDAC3 inhibition resulted in a reduction of activated Iba-1-positive microglia and astrocytes in 5XFAD slices, which was not observed in OBCSs from wild-type mice. mRNA sequencing analysis revealed that HDAC3 inhibition modulated neuronal regenerative pathways related to neurogenesis, differentiation, axonogenesis, and dendritic spine density in OBCSs. Our findings highlight the complexity and diversity of the effects of HDAC3 inhibition on AD models and suggest that HDAC3 may have multiple roles in the regulation of APP expression and processing, as well as in the modulation of neuroinflammatory and neuroprotective genes.

Search in the Periphery for Potential Inflammatory Biomarkers of Dementia with Lewy Bodies and Alzheimer's Disease.

Background: Neuroinflammation, with altered peripheral proinflammatory cytokine production, plays a major role in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease (AD), while the role of inflammation in dementia with Lewy bodies (DLB) is less known and the results of different studies are often in disagreement. Objective: The present study aimed to investigate the levels of TNFα and IL-6 in serum and supernatants, and the related DNA methylation in patients affected by DLB and AD compared to healthy controls (HCs), to clarify the role of epigenetic mechanisms of DNA promoter methylation on of pro-inflammatory cytokines overproduction. Methods: Twenty-one patients with DLB and fourteen with AD were frequency-matched for age and sex with eleven HCs. Clinical evaluation, TNFα and IL-6 gene methylation status, cytokine gene expression levels and production in serum and peripheral blood mononuclear cell (PBMC) supernatants were performed. Results: In AD and DLB patients, higher serum levels of IL-6 and TNFα were detected than in HCs. Differences in LPS-stimulated versus spontaneous PBMCs were observed between DLB, AD, and HC in the levels of TNFα (p = 0.027) and IL-6 (p < 0.001). Higher levels were also revealed for sIL-6R in DLB (p < 0.001) and AD (p < 0.001) in comparison with HC.DNA hypomethylation in IL-6 and TNFα CpG promoter sites was detected for DLB and AD patients compared to the corresponding site in HCs. Conclusions: Our preliminary study documented increased levels of IL-6 and TNFα in DLB and AD patients to HCs. This overproduction can be due to epigenetic mechanisms regarding the hypomethylation of DNA promoters.

Loss of Cholinergic and Monoaminergic Afferents in APPswe/PS1ΔE9 Transgenic Mouse Model of Cerebral Amyloidosis Preferentially Occurs Near Amyloid Plaques.

Alzheimer's disease (AD) is characterized by a loss of neurons in the cortex and subcortical regions. Previously, we showed that the progressive degeneration of subcortical monoaminergic (MAergic) neurons seen in human AD is recapitulated in the APPswe/PS1ΔE9 (APP/PS) transgenic mouse model. Because degeneration of cholinergic (Ach) neurons is also a prominent feature of AD, we examined the integrity of the Ach system in the APP/PS model. The overall density of Ach fibers is reduced in APP/PS1 mice at 12 and 18 months of age but not at 4 months of age. Analysis of basal forebrain Ach neurons shows no loss of Ach neurons in the APP/PS model. Thus, since MAergic systems show overt cell loss at 18 months of age, the Ach system is less vulnerable to neurodegeneration in the APP/PS1 model. We also examined whether the proximity to Aß deposition affected the degeneration of Ach and 5-HT afferents. We found that the areas closer to the edges of compact Aß deposits exhibit a more severe loss of afferents than the areas that are more distal to Aß deposits. Collectively, the results indicate that the APP/PS model recapitulates the degeneration of multiple subcortical neurotransmitter systems, including the Ach system. In addition, the results indicate that Aß deposits cause global as well as local toxicity to subcortical afferents.

Discovery of Potential Drug Targeting Key Genes in Alzheimer's Disease: Insights from Transcriptome Analysis and Molecular Docking.

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder that presents a significant global health challenge. To explore drugs targeting key genes in AD, R software was used to analyze the data of single nuclei transcriptome from human cerebral frontal cortex in AD, and the differentially expressed genes (DEGs) were screened. Then the gene ontology (GO) analysis, Kyoto gene and genome encyclopedia (KEGG) pathway enrichment and protein-protein interaction (PPI) network were analyzed. The hub genes were calculated by Cytoscape software. Molecular docking and molecular dynamics simulation were used to evaluate and visualize the binding between candidate drugs and key genes. A total of 564 DEGs were screened, and the hub genes were ISG15, STAT1, MX1, IFIT3, IFIT2, RSAD2, IFIT1, IFI44, IFI44L and DDX58. Enrichment terms mainly included response to virus, IFN-γ signaling pathway and virus infection. Diclofenac had good binding effect with IFI44 and IFI44L. Potential drugs may act on key gene targets and then regulate biological pathways such as virus response and IFN-γ-mediated signal pathway, so as to achieve anti-virus, improve immune balance and reduce inflammatory response, and thus play a role in anti-AD.

Inhibition of Amyloid-ß (Aß)-Induced Cognitive Impairment and Neuroinflammation in CHI3L1 Knockout Mice through Downregulation of ERK-PTX3 Pathway.

Several clinical studies reported that the elevated expression of Chitinase-3-like 1 (CHI3L1) was observed in patients suffering from a wide range of diseases: cancer, metabolic, and neurological diseases. However, the role of CHI3L1 in AD is still unclear. Our previous study demonstrated that 2-({3-[2-(1-Cyclohexen-1-yl)ethyl]-6,7-dimethoxy-4-oxo-3,4-dihydro-2-quinazolinyl}culfanyl)-N-(4-ethylphenyl)butanamide, a CHI3L1 inhibiting compound, alleviates memory and cognitive impairment and inhibits neuroinflammation in AD mouse models. In this study, we studied the detailed correlation of CHI3L1 and AD using serum from AD patients and using CHI3L1 knockout (KO) mice with Aß infusion (300 pmol/day, 14 days). Serum levels of CHI3L1 were significantly elevated in patients with AD compared to normal subjects, and receiver operating characteristic (ROC) analysis data based on serum analysis suggested that CHI3L1 could be a significant diagnostic reference for AD. To reveal the role of CHI3L1 in AD, we investigated the CHI3L1 deficiency effect on memory impairment in Aß-infused mice and microglial BV-2 cells. In CHI3L1 KO mice, Aß infusion resulted in lower levels of memory dysfunction and neuroinflammation compared to that of WT mice. CHI3L1 deficiency selectively inhibited phosphorylation of ERK and IκB as well as inhibition of neuroinflammation-related factors in vivo and in vitro. On the other hand, treatment with recombinant CHI3L1 increased neuroinflammation-related factors and promoted phosphorylation of IκB except for ERK in vitro. Web-based gene network analysis and our results showed that CHI3L1 is closely correlated with PTX3. Moreover, in AD patients, we found that serum levels of PTX3 were correlated with serum levels of CHI3L1 by Spearman correlation analysis. These results suggest that CHI3L1 deficiency could inhibit AD development by blocking the ERK-dependent PTX3 pathway.

Endothelial DR6 in blood-brain barrier malfunction in Alzheimer's disease.

The impairment of the blood-brain barrier (BBB) has been increasingly recognised as a critical element in the early pathogenesis of Alzheimer's disease (AD), prompting a focus on brain endothelial cells (BECs), which serve as the primary constituents of the BBB. Death receptor 6 (DR6) is highly expressed in brain vasculature and acts downstream of the Wnt/ß-catenin pathway to promote BBB formation during development. Here, we found that brain endothelial DR6 levels were significantly reduced in a murine model of AD (APPswe/PS1dE9 mice) at the onset of amyloid-ß (Aß) accumulation. Toxic Aß25-35 oligomer treatment recapitulated the reduced DR6 in cultured BECs. We further showed that suppressing DR6 resulted in BBB malfunction in the presence of Aß25-35 oligomers. In contrast, overexpressing DR6 increased the level of BBB functional proteins through the activation of the Wnt/ß-catenin and JNK pathways. More importantly, DR6 overexpression in BECs was sufficient to rescue BBB dysfunction in vitro. In conclusion, our findings provide new insight into the role of endothelial DR6 in AD pathogenesis, highlighting its potential as a therapeutic target to tackle BBB dysfunction in early-stage AD progression.

PheSeq, a Bayesian deep learning model to enhance and interpret the gene-disease association studies.

Despite the abundance of genotype-phenotype association studies, the resulting association outcomes often lack robustness and interpretations. To address these challenges, we introduce PheSeq, a Bayesian deep learning model that enhances and interprets association studies through the integration and perception of phenotype descriptions. By implementing the PheSeq model in three case studies on Alzheimer's disease, breast cancer, and lung cancer, we identify 1024 priority genes for Alzheimer's disease and 818 and 566 genes for breast cancer and lung cancer, respectively. Benefiting from data fusion, these findings represent moderate positive rates, high recall rates, and interpretation in gene-disease association studies.

Exploring Acori Tatarinowii Rhizoma and Polygalae Radix in Alzheimer's: Network pharmacology and molecular docking analysis.

Explore Acori Tatarinowii Rhizoma (ATR) and Polygalae Radix (PR) mechanisms in Alzheimer's disease (AD) treatment through network pharmacology. ATR-PR was investigated in the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database, Batman, and Traditional Chinese Medicines Integrated Database (TCMID) to gather information on its chemical components and target proteins. Target genes associated with AD were retrieved from the GeneCards and National Center for Biotechnology Information (NCBI) databases. The integration of these datasets with potential targets facilitated the construction of an AD and ATR-PR protein-protein interaction (PPI) network using the STRING database. The resulting network identified the core active ingredients and main targets of ATR-PR in AD treatment. Cluster analysis of the PPI network was performed using Cytoscape 3.7.1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the Metascape database. Molecular docking simulations revealed potential interactions between the main active ingredients and core targets. Our analysis identified 8 putative components and 455 targets of ATR-PR. We systematically searched for 1306 genes associated with AD, conducted Venn diagram analysis resulting in 156 common targets, and constructed a PPI network with 57 key targets. GO functional analysis highlighted the primary biological processes associated with oxidative stress. KEGG pathway enrichment analysis revealed the involvement of 64 signaling pathways, with the PI3K/Akt signaling pathway playing a key role. Molecular docking analysis indicated a high affinity between the potential targets of ATR-PR and the main compounds of AD. This study sheds light on the complex network of interactions involving ATR-PR in the context of AD. The identified targets, pathways, and interactions provide a foundation for understanding the potential therapeutic mechanisms. The involvement of oxidative stress-related processes and the crucial role of the PI3K/Akt signaling pathway suggest avenues for targeted therapeutic interventions in Alzheimer's disease treatment. Our proposition of the combined use of ATR-PR has emerged as a potential treatment strategy for AD, supported by a network pharmacology approach. This framework provides a robust foundation for future clinical applications and experimental research in the pursuit of effective Alzheimer's disease treatments.