Dysplasia of cortical capillaries as the origin of Alzheimer’s disease: experimental evidence from APP/PS1

doi:10.21203/rs.3.rs-5219476/v1

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Dysplasia of cortical capillaries as the origin of Alzheimer’s disease: experimental evidence from APP/PS1

https://doi.org/10.21203/rs.3.rs-5219476/v1

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To investigate the time course changes of key pathological features of Alzheimer’s disease (AD) and relationship between vascular damage, neuro-inflammation and Aβ in AD model. VEGFR2 expression, vascular number and Aβ levels in cortex and cerebrospinal fluid, cortical and serum inflammatory factor levels, and autonomic activity/memory were analyzed in APP/PS1 mice from 1 to 12-month-old. Transcriptomic analysis of cortical capillaries in one-month-old mice and pathway analysis were performed. Validation of cortical transcriptome data in AD patients from GEO database. Soluble Aβ₁₋₄₂ oligomers were treated with mouse brain vascular pericytes and endothelial cells. APP/PS1 mice had decreased cortical capillary VEGFR2 expression and vascular dysplasia at 1-month-old, increased endothelial cell apoptosis and decreased capillary density at 3-month-old, increased cortical Aβ₁₋₄₂ deposition and neuron apoptosis at 6-month-old. APP/PS1 mice showed decreased autonomic activity and increased memory loss at 9-month-old. Cortical capillary transcriptome profiling indicated that a significant energy metabolism deficit was observed at 1-month-old. Increased mRNA expression of vascular-related genes in elderly surviving AD patients. 0.1µM soluble Aβ₁₋₄₂ oligomers promote angiogenesis, whereas 10µM inhibit it. Cortical capillary dysplasia is a primary contributor to the onset of AD. The accumulation of Aβ in the brain exacerbates vascular hypoplasia by damaging blood vessels, and the interplay between these factors accelerates the progression of AD. Improving vascular functions and energy metabolisms may have potential in delaying or preventing AD.

Alzheimer's disease

blood vessel

neuro-inflammation

neuronal apoptosis

amyloid beta (Aβ)

angiogenesis

Compared to age-matched WT mice, APP/PS1 mice had cortical vascular dysplasia at 1 months, endothelial cell apoptosis at 3 months much earlier than Aβ_1-42 deposition at 6 months.

APP/PS1 mice had cortical neuron apoptosis at 6 months, and increased memory loss and decreased autonomic activity with aging at 9 months, whereas age-matched WT mice had not.

Early APP/PS1 mice show deficient cortex capillary energy metabolism whereas overexpression of energy metabolism-related genes was in survivors with advanced AD patients.

Soluble Aβ_1-42 oligomers at low doses promote angiogenesis, but at 10μM inhibit it in pericytes of capillaries.

Alzheimer’s Disease (AD) is clinically characterized by a decline in cognitive function, memory impairment, and behavioral changes [1]. Extracellular neurons senile plaques (SP) formed by Amyloid-beta (Aβ) peptide deposition in brain parenchyma, and neuronal fiber tangles (NFTs) formed by excessive phosphorylation of intracellular tau protein are the main pathological features of this disease [2–4]. Abnormal deposition of Aβ and tau damage the nervous system, impairing the communication between nerve cells or neurons, consequently leading to cognition decline [5, 6] .

Effective drugs to treat AD are still lacking [7], which either target amyloid/tau or suppress inflammation against, suggesting that other factors may also participate in the pathogenesis of AD [8–10]. Reduced cerebral microvascular density and a large number of ghost vessels (consisting of remnants of microvascular that become acellular and collapse) present in 90% of AD brains and are exacerbated in ApoE4 carriers particularly in the presence of amyloid plaques [11–13]. Early vascular dysfunction in AD includes impairment of blood-brain barrier (BBB) integrity, cerebral microbleeds, cerebrovascular reactivity, resting cerebral blood flow (CBF), and increased cerebrovascular resistance [14, 15]. However, the relationship between vascular disorders and Aβ, neurons, and neuro-inflammation throughout the course of AD development remains unclear. The neurovascular unit (NVU) including endothelial cells, pericytes, neurons and so on regulates BBB permeability and CBF, crucial for maintaining neuronal function [16, 17]. Capillaries, as a component of the NVU, play a critical role in transporting nutrients to the brain's neurons and clearing waste. Age-related vascular changes or vascular pathogenesis could affect neuronal function, potentially contributing to the development of Alzheimer's disease [18, 19].

Therefore, we theorize that capillary pathogenesis and Aβ accumulation influence each other and then both abnormal capillaries and neuronal apoptosis drive Alzheimer's disease progression. To test this hypothesis, we utilized APP/PS1 (Mo/HuAPP695swe and PS1-dE9) double-transgenic mice aged 1–12 months over their lifespan, treated cerebrovascular cells with Aβ oligomers, and analyzed postmortem cortical sequencing data from AD patients [20, 21]. Thus, the purposes of this study were to investigate the change of Aβ expression, inflammatory response, neuronal apoptosis, behavioral changes, the relationship between vascular changes and Aβ oligomers.

Animals

Double transgenic B6.Cg-Tg APP/PS1 (APPswe, PSEN1dE9) 85Dbo/J (stock#034829-JAX) and isogenic parent wild-type C57BL/6J (stock# 000664) mice, and were obtained from the Guangdong Province Experimental Animal Center. Each cage housed three to four mice. There were 10 groups and each 12 mice (6 males and 6 females) for each type, which were euthanized at 1, 3, 6, 9, and 12 months using pentobarbital sodium injection. We recorded survival status from May 2021 to January 2022. Brain tissue, serum, and cerebrospinal fluid (CSF) samples were collected from each mouse. All animals were housed in a pathogen-free facility with a 12-hour light/dark cycle and free access to food and water.

Tissue collection

After an 8-hour fasting, mice were anesthetized with 1% pentobarbital sodium, and CSF was collected from the fourth ventricle using 20 µl glass capillaries. We also collected 100 µl of heparin-anticoagulated blood and 800 µl of non-anticoagulated blood from the heart. The CSF, serum, and plasma were stored in -80°C freezers, while mouse weights and organ weights were recorded. Brain organ coefficient is defined as mouse brain weight divided by body weight ×100. Based on Liu et al.'s l report, brain samples were collected for fixation and freezing [22].

Protein extraction

For each sample, the tissue is weighed and tenfold to add RIPA, such as 30mg of cortex to 300µl PIRA buffer supplemented with protease and phosphatase inhibitors (Beyotime, P0013C) using a grinder (50 Hz) for 45 S, repeated three times at -20℃. The homogenate was then centrifuged at 13,000×g for 20 minutes at 4℃, and the resulting supernatant was transferred to a new 1.5 ml centrifuge tube. The protein supernatants were stored at -80℃ for ELISA detection.

ELISA quantitation

ELISA quantitation for Aβ peptides, p-tau in the cortex and CSF. Commercial ELISA kits for Aβ_1-40 (cat. No. E-EL-M3009) and p-tau (cat. No. E-EL-M1289c) were purchased from Elabscience (Wuhan, China), and for Aβ_1-42 (cat. No. E1151m) from EIAab (Wuhan, China). CSF samples were diluted 20–30 times according to the manufacturer’s protocols for quantifying Aβ_1-42, while cortical protein samples were diluted 2 times for the analysis of Aβ_1-42, Aβ_1-40, and p-tau. Serum and cortical protein samples were diluted 2 times and analyzed using commercial ELISA kits (TNF-α cat. No. EMC102a, IL-1β cat. No. EMC001b, IL-6 cat. No. EMC004) purchased from NeoBioscience (Shenzhen, China) to detect inflammatory cytokines (IL-1β, TNF-α, and IL-6) in serum and cortex.

Behavior experiments

Mice were subjected to an open field test to evaluate behavior, with each group of 10 mice allowed to freely explore a 40 cm × 40 cm × 40 cm box for 5 minutes [23]. The motion that include total movement trail, time spent in the center, speed, and number of entries into the center, were collected using the TopScan system (Clever Sys Inc.; Reston, Virginia, USA). Kraeuter et al. used the Y-Maze test, which consists of three 30 cm arms arranged at 120° angles, to evaluate spatial memory and working memories in mice [24]. Spatial memory in mice was tested using spontaneous alternation, where mice freely explored all three arms for 8 minutes out of curiosity. Working memories are those that endure for long time periods and need training 10 minutes and testing after 2 hours [25].

%Alternation = (Number of alternations / [total number of arm entries – 2])×100

Immunofluorescence Staining

Immunofluorescence staining was performed following previously described methods [26]. Frozen 10 µm sections were thawed at room temperature for 20 minutes, washed with PBS for 5 minutes, and incubated with 5% Bovine Serum Albumin (BSA) and 0.05% TritonX-100 in 1× PBS for 60 minutes at room temperature. They were then incubated overnight at 4℃ with primary antibodies (Aβ_1-42, Abcam, cat. No 201061; CD31, BD, cat. No 550274; vWF, proteintech, cat. No 66682-1-1g; GFAP, Cell Signaling, cat. No 80788; NeuN, Cell Signaling, cat. No 24307; VEGFR2, Cell Signaling, cat. No 2479) diluted 1:250 in PBS with 1%BSA. After washing three times with PBS, sections were incubated with secondary antibodies (1:500, Invitrogen) at room temperature for 2 hours, followed by 5-minute DAPI staining, and imaging using a BX63 fluorescence microscope (Olympus, Japan).

Quantification of micro-vessels

CD31 and vWF fluorescence staining on frozen cortex sections evaluated cortical micro-vessels. AngioTool software analyzed parameters such as vascular network area, vessel count, length, density, lacunarity, and branching index (branch points per unit area), assessing sprouting activity [27]. The software (Home - Home - CCR Wiki (cancer.gov)) was used to analyze the capillaries with the adjustment for vessel diameter to 5-100 µm and background removal in our study.

RNA-Seq of mouse capillary

Capillary from three randomly selected 1-month-old APP/PS1 mice and three age-matched WT mice in the cortex were isolated for transcriptomic profiling using previously described methods [28, 29]. Total RNA was extracted using the miRNeasy Mini Kit (cat. No 217004) and sequenced on Illumina NovaSeq6000 sequencers in PE150 mode at Shanghai Biotechnology Corporation. Differentially expressed genes (DEGs) were analyzed using the DeSeq2 package, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses using R packages.

RNA-Seq in AD Patients

GSE203206 dataset was downloaded from the Gene Expression Omnibus (GEO), which was generated from Brodmann Area 17 of the occipital lobe tissue in brain collected from 8 non-demented control (NDC) and 40 AD patients Participants were classified based on cognitive tests: MMSE, BIMC, and Mattis' DRS. Differential expression analysis was done with GEO2R, identifying significant genes with p < 0.05.

Aβ₁₋₄₂ Oligomers on cells

Mouse brain microvascular cells pericytes that is the immortalized cells isolated by our group and endothelial cells (bEnd.3) was purchased from Cellcook Biotech Corporation (cat. No CC9006). They were cultured in DMEM high glucose (Gibco, USA) with 10% FBS and 1% antibiotics (streptomycin, penicillin, and fungitin) in a humidified incubator with 5% CO₂ at 37°C. During experiments, cells were treated with Aβ oligomers at 70% low density. For the preparation of Aβ derived diffusion ligand (ADDL), refer to Chromy BA et al [30]. Brief, the solid Aβ peptide dissolved in cold hexafluoro-2-propanol (HFIP) and incubated at room temperature for 1 hour, evaporating HFIP overnight in a fume hood, and storing the peptides as membranes at -80°C. The film dissolved in anhydrous DMSO to 1 mM, then diluted to 500 µM with phenol-free red F12 and aged for 36 hours at 4°C. The supernatant containing soluble oligomers were obtained after centrifugation at 13,000 rpm for 15 minutes at 4°C. Cells were treated with Aβ₁₋₄₂ Oligomers at different concentrations (0.1µM, 1µM, 2µM, 5µM, 10µM) for 24 hours, and 0µM dissolved in DMSO as control. Only immortalized cell of pericytes treated with Aβ oligomers were seeded in a 48-well plate with 110 µl of matrix gel (cat. No 354234) and observed for angiogenesis after 8 hours with AngioTool to evaluate the results.

RNA extraction and quantitative PCR

Frozen hippocampus (n = 3) and cortex (n = 3) tissues (25 mg each) were homogenized in 500 µl Trizol (Invitrogen, cat. No 15596018) mash three cycles of 30 S for 50 Hz at -20°C in a grinder, and RNA extraction from pericytes and endothelial cells treated with Aβ₁₋₄₂ oligomers followed similar methods. The homogenates were used for total RNA extraction and cDNA Kit (Takara, cat. No RR047A), following the manufacturer's instructions. The relative mRNA levels of GFAP, Iba1, CD31, IL-1β, IL-6, TNF-α, TGF-β2, Caspase-1, Caspase-3, VEGFA, and VEGFR2 genes were analyzed using quantitative PCR (qPCR) on an ABI 3421 Real-Time PCR system (ABI, Commonwealth of Massachusetts, USA). The qPCR reaction conditions and components followed the methods outlined in the study by Sun et al [31]. β-actin served as the internal reference gene, and the primer sequences were adapted from Liu et al.'s study [32]. All primer sequences are provided in Supplementary Table 1.

Statistical analysis

All data were analyzed using SPSS 22.0 and visualized with GraphPad Prism 8.0. Two-way ANOVA with Bonferroni post-tests was used for group comparisons, and one-way ANOVA assessed AD-related markers (Aβ_1-42, Aβ_1-40, p-tau) in APP/PS1 groups. Linear regression was used to evaluate the association between the CSF Aβ_1-42 and the cortex Aβ_1-42. Survival data were analyzed using Kaplan-Meier curves, abnormal data were assessed nonparametrically, and statisticians were blinded to the experimental results. A p-value of < 0.05 (two-sided) indicated statistical significance. "*" denotes comparison between two groups of mice with the same age, and "#" denotes comparison between APP/PS1 mice at different ages. *p < 0.05, **p < 0.01, ***p < 0.001. #p < 0.05, ##p < 0.01, ###p < 0.001.

The change of body weight, brain organ coefficient, and survival rate of APP/PS1 mice over time from 1 to 12 months

Compared to age- and sex-matched WT mice, APP/PS1 transgenic mice At 1 month old show heavier weight, lower brain organ coefficient (Fig. 1C), and a shorter survival (p = 0.012) (Fig. 1). The mortality rate of APP/PS1 mice was 14.14% (297 mice total), and higher than 3% in WT mice (100 mice total) from 1 to 12 months old. This indicate that a survivor effect in APP/PS1 mice surviving beyond 6–9 months may exist, with evidence at 12 months old. More female mice survived to 12 months than male.

Decreased autonomic activity and increased memory loss in 9 months APP/PS1 mice

With aging, APP/PS1 mice showed declined autonomic activity, whereas WT type mice demonstrated increased activity at 9 and 12 months (Fig. 2, A and B). The open field test revealed that compared to age-matched WT mice, APP/PS1 mice exhibited significantly reduced total motion distance at 9 months (p < 0.001) and 12 months (p < 0.001), with no significant change observed from 1 to 6 months APP/PS mice (Fig. 2B). Compared with 9-month-old WT mice, APP/PS1 mice had decreased number of center entered (Fig. 2C) and moved at slower speeds both in overall field (Fig. 2, D and E). Specifically, the speed of APP/PS1 mice in the center area was lower compared to WT mice aged 1, 3, 6, 9, and 12 months, indicating reduced exploration behavior in AD mice (Fig. 2D) [33]. From 3 to 9 months, APP/PS1 mice entered the central area less often. At 9 months, they entered less frequently than age-matched WT mice, indicating a tendency toward depression, although this improved by 12 months (Fig. 2C). Overall, this suggests that APP/PS1 mice have limited movement, slower behavior, signs of depression, increased anxiety, and reduced exploration compared to WT mice.

Our study found that at 9 months, APP/PS1 mice exhibited decreased spatial and learning memory. In the Y-maze test, the spontaneous alternation rate decreased steadily from 3 to 9 months, significantly lower at 9 months compared to 3 and 6 months of APP/PS1 mice, and 9 months of WT mice (p < 0.001) (Fig. 2G). A decline learning memory, 9 months APP/PS1 mice spent less time in new arms compared to 1 and 6 months APP/PS1 mice, and 9 months WT mice, with statistically significant differences (Fig. 2H). Figure S1 revealed slight performance variations between male and female APP/PS1 mice, but overall, their trends remained consistent. Notably, both spatial and reference memory in APP/PS1 mice showed improvement by 12 months, potentially linked to fewer instances of neuronal apoptosis as they 12 months in Fig. 6C.

Reduced clearance of Aβ _1-42 in CSF, and starting to deposition in cortex at 6 months APP/PS1 mice

No Aβ₁₋₄₂ plaques were deposited in the cortex of WT mice with aging (Fig. 3, A and B). However, in APP/PS1 mice, Aβ₁₋₄₂ deposition in the cortex started at 6 months and increased over time, consistent with previous studies (Fig. 3, B and Figure S2) [34]. By 12 months, there were more plaques in the cortex compared to 6 months (p < 0.001) and 9 months (p < 0.001) (Fig. 3B). The concentration of Aβ₁₋₄₂ in the cortex of APP/PS1 mice was 2694 pg/ml at 12 months, higher than the 2044 pg/ml at 9 months (Fig. 3C). However, Aβ₁₋₄₂ levels in the CSF declined with age, peaking at 3 months and decreasing to very low levels by 9 and 12 months (Fig. 3D). There was a significant negative correlation between Aβ₁₋₄₂ levels in the cortex and in CSF (r = -0.706, p < 0.001) (Fig. 3E). This suggests that reduced clearance of Aβ₁₋₄₂ through CSF in early AD stages and impaired release into CSF may contribute to its accumulation in the cortex. In 9-month-old APP/PS1 mice, p-tau protein levels were higher in the cortex than in 6-month-old mice (Fig. 3H). Figure S3 shows that Aβ levels were slightly more severe overall in female APP/PS1 mice compared to males.

Neuron apoptosis increased in 6-month-old APP/PS1 mice

Compared to age-matched WT mice, APP/PS1 mice had fewer neurons at 1, 3, 6, and 9 months (p < 0.05) (Fig. 4, A and B). Neuron apoptosis increased at 6 and 9 months in APP/PS1 mice and was significantly higher (Fig. 4, C and Figure S4 (middle column)), while it decreased down to the level in WT mice at 12-month-old APP/PS1 mice, a possible survivor effect. In contrast, no neuron apoptosis was observed in C57BL/6J mice from 1 to 12 months (Figure S4, left column). Caspase-3 mRNA levels were consistently higher in the cortex of APP/PS1 mice from 1 to 12 months, showing significant differences compared to age-matched WT mice (p < 0.05) (Fig. 4D).

The levels of inflammation factors increased at APP/PS1 mice

The levels of inflammatory markers IL-6, IL-1β, TNF-α and the anti-inflammatory factor TGF-β2. IL-6, TGF-β2, and TNF-α mRNA expression in the APP/PS1 mouse cortex showed a funnel-shaped over time and were higher compared to WT mice at all time points, with statistically significant differences except for TNF-α at 9 months (Fig. 5A). However, no significant differences at protein levels in cortex were observed between WT and APP/PS1 mice (Fig. 5B). Serum levels of IL-6, IL-1β, and TNF-α in APP/PS1 mice showed a bell-shaped pattern, peaking at 3 months (Fig. 5C). Serum IL-1b showed significantly higher in APP/PS1 mice compared to WT mice at month 3. These findings suggest that systemic rather than local inflammation may exist in APP/PS1 mice in early life.

Activated astrocytes surrounded capillaries in 1-month-old and increased with aging in APP/PS1 mice

Astrocytes have been observed accumulating Aβ deposits in previous studies [35, 36]. We noted Aβ and activated astrocytes around capillaries (Figure S5 and S6). The level of glial fibrillary acidic protein (GFAP), which is expressed in several cell types of the central nervous system (CNS) including astrocytes and ependymal cells during the development, were significantly higher in the cortex of 3-, 6-, 9-, and 12-month-old APP/PS1 mice compared to age-matched WT mice (Fig. 5E). Activated astrocytes surrounded micro-vessels in 1-month-old APP/PS1 mice (Fig. 5, D and Figure S6). Michael et al. found that reactive astrocytes protect and repair existing vessels and support new vessel formation after cerebral ischemia [37]. GFAP, CD31, and Iba1 mRNA levels increased with age in APP/PS1 mice. GFAP mRNA was notably higher in 6-, 9-, and 12-month-old APP/PS1 mice compared to age-matched WT mice (Fig. 5F). Similarly, Endothelial cell marker CD31 mRNA levels in the cortex of 1-, 9-, and 12-month-old APP/PS1 mice were significantly increased compared to age-matched WT mice (Fig. 5G). The GFAP/CD31 mRNA ratio was higher in 6-, 9-, and 12-month-old APP/PS1 mice compared to age-matched WT mice (Fig. 5H). Additionally, microglial cell marker Iba1 mRNA levels in the cortex of 3-, 6-, and 12-month-old APP/PS1 mice were elevated compared to age-matched WT mice (Fig. 5I). These findings indicate that the trend of astrocyte activation and endothelial cell proliferation may exist in APP/PS1 mice in early life.

Cortical vascular dysplasia starting in 1-month-old and endothelial cell apoptosis increased at 3-month-old APP/PS1 mice

Early studies show capillaries are closely linked to amyloid fibrils, which form senile plaques in AD [38]. Activated astrocytes surround vessels in the cortex, prompting us to investigate vessel development and apoptosis. Immunofluorescence staining of vessel marker CD31 (PECAM-1) and vWF, showed fewer capillaries in the cortex of 3 months APP/PS1 mice compared to WT mice (Fig. 6A). The vascular area in APP/PS1 mice was lower than in WT mice at months 3 and 12 (Fig. 6, B and Figure S7B). The total number of endpoints with CD31 was lower in APP/PS1 mice at months 1, 3, and 12 compared to age-matched WT mice (Fig. 6C) (p < 0.05), and with vWF at months 1, 3, 6, 9, and 12 (Figure S7C) (p < 0.05). The total vascular length was shorter in APP/PS1 mice at months 1, 3, 9, and 12 compared to age-matched WT mice (p < 0.05) (Fig. 6, D and Figure S7D). These results suggest that vascular atrophy may exist in AD mice in the early stage of development. APP/PS1 mice had fewer vascular junction densities with CD31 at months 1, 6, 9, and 12 (Fig. 6E), and with vWF at months 1, 3, 9, and 12 (Figure S7E), with significant differences (p < 0.05). Consistent with the results of 5xFAD and TgCRND8 mice at 12 months of age [39], the VEGFR2 level of APP/PS1 mice at 12 months of age also increased compared with age-matched WT mice. APP/PS1 mice had lower cortical VEGFR2 protein levels compared to WT mice, except at 12 months, starting from 1 month (Fig. 6, F and G, and Figure S8). VEGFR2 mRNA levels were higher than in WT mice at 1, 3, 9, and 12 months (Fig. 6H), remaining elevated even after normalization with CD31 (Fig. 6I). The increase in mRNA levels could be explained by the repair mechanisms activated in response to decreased vessel density. Vascular cell adhesion molecule 1 (VCAM-1) that markers of vascular inflammation, the mRNA levels consistently increased in the cortex of APP/PS1 mice from 1 to 9 months, but decreased at month 12 (Fig. 6, J and K). TUNEL assay results showed that microvascular apoptosis in APP/PS1 mice started from month 3, and peaked at 6 months and gradually slightly decreased at 9 and 12 months (Fig. 6, L and Figure S4(right column)). Typically, vascular development peaks in mice from 1 to 3 months [40], with WT mice improving vascular function until 6 months (Fig. 6G) while APP/PS1 mice begin to show Aβ deposits (Figure S2). The AD model underwent two stages: developmental stage (1 to 6 months) and dementia stage (9 to 12 months) in APP/PS1 mice. In the developmental stage, Aβ concentration was positively correlated with cortical vascular network development, with significant results for total and average vessel length (Supplementary Table 2). In the dementia stage, Aβ concentration and cortical vascular network showed negative correlation, but this was not statistically significant. Figure S9 shows the mRNA levels of genes such as ICAM-1 and VEGFA. These findings suggest partial angiogenesis but overall cortical vascular atrophy in AD mice.

Vascular energy metabolism deficit and Neovascular Weakness in early AD

At one months, APP/PS1 mice exhibit abnormal cortical vasculature compared to WT mice, and we investigated the underlying mechanism using transcriptome profiling of cortical capillaries. Analysis of DGEs revealed distinct gene expression patterns between 1-month-old APP/PS1 (n = 3) and age-matched WT (n = 3) mice (Fig. 7A). A volcano plot highlighted 462 DEGs between APP/PS1 and WT mice, with 299 genes down-regulated and 163 genes up-regulated (Fig. 7B). KEGG enrichment analysis indicated enrichment of metabolism-related pathways (Fig. 7C). Specifically, in the top lists such as Global and overview maps, 28 genes were down-regulated and 9 genes were up-regulated. Of Amino acid metabolism, Energy metabolism, 9 genes (mt-Nd4l, mt-Nd4, mt-Nd5, mt-Nd2, mt-Cytb, mt-Atp8, mt-Nd3, mt-Atp6, mt-Nd1) were down-regulated in the Oxidative phosphorylation tertiary pathway. GO analysis showed that NADH ubiquitination activation (Fig. 7D). These results suggest that metabolic changes in brain capillary vasculature may be linked to AD. In contrast, analysis of occipital lobe transcriptomic data (GSE203206) including 40 AD and 8 NDCS patient samples revealed up-regulation of oxidative phosphorylation genes (mt-Nd4l, mt-Nd4, mt-Nd5, mt-Nd2, mt-Cytb, mt-Atp8, mt-Nd3, mt-Atp6, mt-Nd1) in post-mortem AD patients (Fig. 7E). Vascular-related genes (CD31, ICAM1, VEGFA, VEGFB, VASH1, ANGPT1) were also up-regulated (Fig. 7F). The up-regulation of these genes may attributed to the older age and longer survival of the AD patients.

Aβ oligomers promote angiogenesis at low doses, inhibit at high doses

According to previous studies [41, 42], we treated two types of mouse brain vascular cells with 0–10 µM Aβ oligomers for 24h. At concentrations of 0.1 and 1.0 µM, Aβ oligomers decreased mRNA levels of VEGFR2 and Caspase-3 genes in endothelial cells compared to the control (Fig. 8, B and C). However, 2 µM Aβ oligomers reduced mRNA levels of VEGFR2, Caspase-3 genes in endothelial cells (Fig. 8C). At lower doses, Aβ treatment altered the expression of the apoptosis-related genes Caspase-3 and we observed obvious apoptosis in endothelial cells. Further in vitro studies investigated the effects of Aβ on angiogenesis with pericytes. Specifically, 0.1 µM Aβ oligomers increased the total vessel length, vessel percentage area, total number of junctions and 1 µM increased junction density in pericytes (p < 0.05) (Fig. 8E-I). However, 10 µM Aβ oligomers decreased the vessel percentage area and total number of endpoints in pericytes (Fig. 8G). These findings indicate that low doses of Aβ oligomers can promote angiogenesis, while higher doses inhibit it. The results of in vitro study were consistent with the results of relatively high cortical Aβ concentration and poor vascular network development in APP/PS1 mice during the disease stage (9 to 12months).

APP/PS1 transgenic mice (Jackson's lab) are commonly used to study Alzheimer's disease, amyloid plaque formation, and aging, with plaques typically appearing at 6–7 months [21]. This study observed various Alzheimer's disease features, including behavior, Aβ, inflammation, neurons, and blood vessels over the first 12 months after birth, covering the entire development process, unlike most studies that focus only on elderly mice aged 10–14 months (Fig. 9) [43]. At 1 month old, APP/PS1 mice displayed initial AD symptoms such as abnormal cerebral nerves and cortical capillaries, followed by Aβ deposition and behavioral changes. They showed fewer cortical vascular endpoints, shorter vascular length, decreased neurons, increased cortical inflammation, and higher astrocyte activation compared to age-matched wild-type mice.

In our study, we found that low concentrations of Aβ, resembling the early stages of Alzheimer's disease, promote angiogenesis in pericytes. Conversely, higher concentrations of Aβ, characteristic of the disease's late stages, inhibit angiogenesis. This finding is consistent with the previous studies that Aβ₁₋₄₂ increases VEGFR1 and decreases VEGFR2 expression in brain endothelial cells [44, 45]. VEGFR2 has a stronger angiogenic activity and tyrosine kinase activity than VEGFR1 [46]. Szu et al. showed that the AD model of Tg2576 had serious Aβ deposits and cerebrovascular dysfunction at 19 months [47]. We observed early changes in AD that VEGFR2 mRNA levels increased at 1 months mice, while VEGFR2 protein levels decreased in the cortex. Dysplasia of vascular could cause ischemia and hypoxia, leading to cortical atrophy. Nakajima et al. observed that capillary sprouting sites decreased and capillary diameter increased in PS1-deficient mouse brains, with microvascular density in the cortex of AD mice decreasing significantly by 40% from 6 to 12 months [48, 49]. However, fewer vascular junction densities, the total number of endpoints and total vascular length decreased in the cortex of 1 months APP/PS1 in our study. Endothelial cell apoptosis increased at 3 months and neuron apoptosis appeared at 6 months in APP/PS1 mice, whereas it was almost undetectable in age-matched C57BL/6J mice. The increase in neuron death at 6 months might be due to the large amount of Aβ deposition. Aβ₁₋₄₂ oligomers significantly elevated extracellular glutamate and caused neuronal necrosis [50]. Totally, the onset of vascular dysplasia at 1-month-old was much earlier than neuron apoptosis and Aβ deposition.

Aβ is mainly cleared through the blood-brain barrier, parenchymal cells, CSF, and the lymphatic system. Aβ₁₋₄₂ deposition in the cortex may be due to impaired Aβ clearance through the CSF [51]. In our study, Aβ₁₋₄₂ levels decreased in the CSF and increased in the cortex of 6-month-old APP/PS1 mice. We hypothesized that vascular dysplasia is the primary cause of reduced Aβ clearance, significantly promoting the progression of AD. Our findings emphasize a shift in focus from aging to early disease development, highlighting the importance of intervening during the early disease window. In our on-going study, we are investigating whether administering the Aβ antibody drug Donanemab to 1-month-old mice could yield better outcomes.

At early stage of Alzheimer's disease, activated microglia and astrocytes helps clear Aβ. With the disease advances, prolonged microglial activation can lead to too many pro-inflammatory cytokines, neuro-inflammation and worsen amyloid-beta accumulation and neurodegeneration [52, 53]. In 9- and 12-month-old APP/PS1 mice, we observed higher levels of IL-1β, IL-6, and TNF-α in both the cortex and serum. Lopez-Rodriguez et al. demonstrated that astrocytes produce an excessive chemokine in response to IL-1β in the hippocampus [54]. We observed cerebrovascular pathology in APP/PS1 mice, which was linked to extensive reactive astrocyte activation and neurodegenerative changes.

AD is the most common neurodegenerative disorder, known for causing gradual memory and cognitive decline. In our study, we found that APP/PS1 mice exhibited significantly reduced movement in the open field test, and is consistent with Kraeuter et al.'s findings of decreased activity in the center and increased stereotypical behavior in 9-month-old mice [23]. We also found that 9-month-old APP/PS1 mice exhibited decreased spontaneous alternation and fewer explorations of the novel arm, and is consistent with Lok et al.'s findings that impaired prefrontal cortex function is due to Aβ₁₋₄₂ deposition [24, 55]. As Gallagher's findings, female mice showed worse behavioral performance and higher cortical Aβ deposition [56]. We observed that females had higher Aβ levels than males at 9 and 12 months, and had worse spatial memory than males at 9 months. These findings are in agreement with the previous studies [57].

In our study, the mortality rates were 10.10% at 6 months and 14.14% at 12 months for APP/PS1 mice. However, Xiong et al. reported that a higher premature death rate (about 35%) in the mice before 6 months of age [58]. We found that from 9 to 12 months old, the mortality rate of APP/PS1 mice was 3%, similar to WT of natural mortality rate, suggesting that a survivor effect in late stages of Alzheimer's disease may exist. There are more women than men with the AD, particularly over the age of 85 years, due to sex-dependent difference in life expectancy [59]. Niu et al.'s study found a higher prevalence of Alzheimer's disease in women (7.13%) compared to men (3.31%) in Europe, and is consistent with our observation that more females survive in 12-month-old APP/PS1 mice [60]. Previous studies on male APP/PS1 mice had limitations in reflecting the population accurately, and using both genders of the mice along with littermate controls would provide a more comprehensive study design [61, 62]. A limitation of our study is the lack of littermate controls.

Mitochondrial dysfunction is a hallmark of aging, affecting cellular energy metabolism [63]. Glucose metabolism markedly is reduced in AD and aMCI, with lower mtDNAcn associated with worse cognitive function, indicating the deficits of mitochondrial energy metabolism in AD patients [64, 65]. Our study found down-regulation of vascular energy metabolism genes in early-stage AD. Hou et al. reported that NAD + supplements might enhance vascular status and potentially improve Alzheimer's disease outcomes [66]. We found elevated expression of mitochondrial energy and angiogenesis-related genes in post-mortem AD patients, which is possibly influenced by survivor effects. Exploring how replenishing mitochondrial energy alters cognitive improvement is warranted, and may pave an avenue to develop non-Aβ-targeted therapies to prevent or delay AD.

First, the innate overexpression of the APP/PS1 gene in AD model mice leads to vascular dysplasia, which is accompanied by a reduced number of neurons and activation of astrocytes around brain micro-vessels. Second, this vascular dysplasia (characterized by dysfunction or a reduction in vessel number) impairs the clearance of Aβ through brain vessels and disrupts metabolic pathways in the liver, accelerating Aβ deposition. In later stages of the disease, and in vitro studies, accumulated Aβ is found to be toxic to blood vessels, causing further vascular and cortex atrophy—an important clinical feature of AD. This vicious cycle, combined with neuro-inflammation, increases neuronal apoptosis and nerve damage. Early mitochondrial dysfunction in capillaries may play a start role in all of this process, though further mechanistic studies are required.

AD	Alzheimer's disease
APP	Amyloid beta precursor protein
Aβ	amyloid beta
SP	senile plaques
NFTs	neuronal fiber tangles
BBB	blood-brain barrier
CBF	cerebral blood flow
NVU	neurovascular unit
CSF	Cerebral spinal fluid
RT-PCR	Reverse transcription-polymerase chain reaction
IL-6	Interleukin-6
IL-1β	Interleukin-1β
TNF-α	tumor necrosis factor
TGF-β2	Transforming growth factor beta 2
caspase-3	cysteine aspartic acid-specific protease 3
caspase-1	cysteine aspartic acid-specific protease 1
NLRP3	NLR pyrin domain containing 3
CD31	Platelet endothelial cell adhesion molecule-1
VEGFA	Vascular endothelial growth factor A
VEGFR2	Vascular Endothelial Growth Factor Receptor 2
GFAP	glial fibrillary acidic protein
Iba-1	Ionized calcium binding adaptor molecule-1

Acknowledgements

Not applicable.

Authors’ contributions

Yun He designed the research study, provided financial support. Yirong Xie and Yao Lu wrote the manuscript. Yun He and Lingeng Lu revised the manuscript. Yirong Xie, Shurong Pi, Jingyi Zhong, Xin Li acquired and analyzed data. Yirong Xie, Hongya Li, Heng Su, Zhiqiang Zhao, Qing Wei, Fubin Chen performed the experiments. All authors discussed the results and commented on the manuscript.

Funding

This project was supported by grants from the National Natural Science Foundation of China (No. 81472998, 81872661). The foundation had no role in the study design, data collection and analysis, manuscript preparation, or the decision to publish.

Ethics approval and consent to participate

All the study protocols involving mice were approved by the Sun Yat-sen University Animal Care Committee, 2022 (No.011) and comply with the Institute's animal ethics guidelines.

Consent for publication

Not applicable.

Competing interests

All authors report no biomedical financial interests or potential conflicts of interest.

World Alzheimer Report (2023) https://www.alzint.org/u/World-Alzheimer-Report-2023.pdf
Braak H, Braak E (1991) Neuropathological stageing of Alzheimer-related changes. Acta Neuropathol 82:239–259
Thal DR, Rüb U, Orantes M, Braak H (2002) Phases of A beta-deposition in the human brain and its relevance for the development of AD. Neurology 58:1791–1800
Wojtas AM, Kang SS, Olley BM, Gatherer M, Shinohara M, Lozano PA et al (2017) Loss of clusterin shifts amyloid deposition to the cerebrovasculature via disruption of perivascular drainage pathways. Proc Natl Acad Sci U S A 114:E6962–e71
Roos TT, Garcia MG, Martinsson I, Mabrouk R, Israelsson B, Deierborg T et al (2021) Neuronal spreading and plaque induction of intracellular Aβ and its disruption of Aβ homeostasis. Acta Neuropathol 142:669–687
Hardy JA, Higgins GA (1992) Alzheimer's disease: the amyloid cascade hypothesis. Science 256:184–185
Mintun MA, Lo AC, Duggan Evans C, Wessels AM, Ardayfio PA, Andersen SW et al (2021) Donanemab in Early Alzheimer’s Disease. New Engl J Med 384:1691–1704
Mangialasche F, Solomon A, Winblad B, Mecocci P, Kivipelto M (2010) Alzheimer's disease: clinical trials and drug development. Lancet Neurol 9:702–716
Ray WJ, Buggia-Prevot V (2021) Novel Targets for Alzheimer's Disease: A View Beyond Amyloid. Annu Rev Med 72:15–28
Ossenkoppele R, van der Kant R, Hansson O (2022) Tau biomarkers in Alzheimer's disease: towards implementation in clinical practice and trials. Lancet Neurol 21:726–734
Riddle DR, Sonntag WE, Lichtenwalner RJ (2003) Microvascular plasticity in aging. Ageing Res Rev 2:149–168
Csiszar A, Tarantini S, Fulop GA, Kiss T, Valcarcel-Ares MN, Galvan V et al (2017) Hypertension impairs neurovascular coupling and promotes microvascular injury: role in exacerbation of Alzheimer's disease. Geroscience 39:359–372
Hunter JM, Kwan J, Malek-Ahmadi M, Maarouf CL, Kokjohn TA, Belden C et al (2012) Morphological and pathological evolution of the brain microcirculation in aging and Alzheimer's disease. PLoS ONE 7:e36893
Sweeney MD, Montagne A, Sagare AP, Nation DA, Schneider LS, Chui HC et al (2019) Vascular dysfunction-The disregarded partner of Alzheimer's disease. Alzheimers Dement 15:158–167
Sen A, Capelli V, Husain M (2018) Cognition and dementia in older patients with epilepsy. Brain 141:1592–1608
Kisler K, Nelson AR, Montagne A, Zlokovic BV (2017) Cerebral blood flow regulation and neurovascular dysfunction in Alzheimer disease. Nat Rev Neurosci 18:419–434
Attwell D, Buchan AM, Charpak S, Lauritzen M, Macvicar BA, Newman EA (2010) Glial and neuronal control of brain blood flow. Nature 468:232–243
Cortes-Canteli M, Iadecola C (2020) Alzheimer's Disease and Vascular Aging: JACC Focus Seminar. J Am Coll Cardiol 75:942–951
Lipsman N, Meng Y, Bethune AJ, Huang Y, Lam B, Masellis M et al (2018) Blood-brain barrier opening in Alzheimer's disease using MR-guided focused ultrasound. Nat Commun 9:2336
Jankowsky JL, Slunt HH, Gonzales V, Jenkins NA, Copeland NG, Borchelt DR (2004) APP processing and amyloid deposition in mice haplo-insufficient for presenilin 1. Neurobiol Aging 25:885–892
Reiserer RS, Harrison FE, Syverud DC, McDonald MP (2007) Impaired spatial learning in the APPSwe + PSEN1DeltaE9 bigenic mouse model of Alzheimer's disease. Genes Brain Behav 6:54–65
Liu J, Xie Y, Lu Y, Zhao Z, Zhuang Z, Yang L et al (2023) APP/PS1 Gene-Environmental Cadmium Interaction Aggravates the Progression of Alzheimer's Disease in Mice via the Blood-Brain Barrier, Amyloid-β, and Inflammation. J Alzheimers Dis
Kraeuter AK, Guest PC, Sarnyai Z (2019) The Open Field Test for Measuring Locomotor Activity and Anxiety-Like Behavior. Methods Mol Biol 1916:99–103
Kraeuter AK, Guest PC, Sarnyai Z (2019) The Y-Maze for Assessment of Spatial Working and Reference Memory in Mice. Methods Mol Biol 1916:105–111
Guitar NA, Roberts WA (2015) The interaction between working and reference spatial memories in rats on a radial maze. Behav Processes 112:100–107
Im K, Mareninov S, Diaz MFP, Yong WH (2019) An Introduction to Performing Immunofluorescence Staining. Methods Mol Biol 1897:299–311
Zudaire E, Gambardella L, Kurcz C, Vermeren S (2011) A computational tool for quantitative analysis of vascular networks. PLoS ONE 6:e27385
Lee YK, Uchida H, Smith H, Ito A, Sanchez T (2019) The isolation and molecular characterization of cerebral microvessels. Nat Protoc 14:3059–3081
Zhang H, He Y, Dai S, Xu Z, Luo Y, Wan T et al (2008) AIP1 functions as an endogenous inhibitor of VEGFR2-mediated signaling and inflammatory angiogenesis in mice. J Clin Invest 118:3904–3916
Chromy BA, Nowak RJ, Lambert MP, Viola KL, Chang L, Velasco PT et al (2003) Self-assembly of Abeta(1–42) into globular neurotoxins. Biochemistry 42:12749–12760
Sun Y, Zhao Z, Zhang H, Li J, Chen J, Luan X et al (2020) The interaction of lead exposure and CCM3 defect plays an important role in regulating angiogenesis through eNOS/NO pathway. Environ Toxicol Pharmacol 79:103407
Liu J, Xie Y, Lu Y, Zhao Z, Zhuang Z, Yang L et al (2023) APP/PS1 Gene-Environmental Cadmium Interaction Aggravates the Progression of Alzheimer's Disease in Mice via the Blood-Brain Barrier, Amyloid-β, and Inflammation. J Alzheimers Dis 94:115–136
Janus C, Flores AY, Xu G, Borchelt DR (2015) Behavioral abnormalities in APPSwe/PS1dE9 mouse model of AD-like pathology: comparative analysis across multiple behavioral domains. Neurobiol Aging 36:2519–2532
Pedrós I, Petrov D, Allgaier M, Sureda F, Barroso E, Beas-Zarate C et al (2014) Early alterations in energy metabolism in the hippocampus of APPswe/PS1dE9 mouse model of Alzheimer's disease. Biochim Biophys Acta 1842:1556–1566
Smit T, Deshayes NAC, Borchelt DR, Kamphuis W, Middeldorp J, Hol EM (2021) Reactive astrocytes as treatment targets in Alzheimer's disease-Systematic review of studies using the APPswePS1dE9 mouse model. Glia 69:1852–1881
Wu S, Liu H, Zhao H, Wang X, Chen J, Xia D et al (2020) Environmental lead exposure aggravates the progression of Alzheimer's disease in mice by targeting on blood brain barrier. Toxicol Lett 319:138–147
Williamson MR, Fuertes CJA, Dunn AK, Drew MR, Jones TA (2021) Reactive astrocytes facilitate vascular repair and remodeling after stroke. Cell Rep 35:109048
Miyakawa T (2010) Vascular pathology in Alzheimer's disease. Psychogeriatrics 10:39–44
Tataryn NM, Singh V, Dyke JP, Berk-Rauch HE, Clausen DM, Aronowitz E et al (2021) Vascular endothelial growth factor associated dissimilar cerebrovascular phenotypes in two different mouse models of Alzheimer's Disease. Neurobiol Aging 107:96–108
Naito H, Iba T, Takakura N (2020) Mechanisms of new blood-vessel formation and proliferative heterogeneity of endothelial cells. Int Immunol 32:295–305
Akhter R, Shao Y, Formica S, Khrestian M, Bekris LM (2021) TREM2 alters the phagocytic, apoptotic and inflammatory response to Abeta(42) in HMC3 cells. Mol Immunol 131:171–179
Deng Z, Wang J, Xiao Y, Li F, Niu L, Liu X et al (2021) Ultrasound-mediated augmented exosome release from astrocytes alleviates amyloid-beta-induced neurotoxicity. Theranostics 11:4351–4362
Ali M, Falkenhain K, Njiru BN, Murtaza-Ali M, Ruiz-Uribe NE, Haft-Javaherian M et al (2022) VEGF signalling causes stalls in brain capillaries and reduces cerebral blood flow in Alzheimer's mice. Brain 145:1449–1463
Singh Angom R, Wang Y, Wang E, Pal K, Bhattacharya S, Watzlawik JO et al (2019) VEGF receptor-1 modulates amyloid β 1–42 oligomer-induced senescence in brain endothelial cells. FASEB J 33:4626–4637
Weekman EM, Sudduth TL, Caverly CN, Kopper TJ, Phillips OW, Powell DK et al (2016) Reduced Efficacy of Anti-Aβ Immunotherapy in a Mouse Model of Amyloid Deposition and Vascular Cognitive Impairment Comorbidity. J Neurosci 36:9896–9907
Mabeta P, Steenkamp V (2022) The VEGF/VEGFR Axis Revisited: Implications for Cancer Therapy. Int J Mol Sci. ;23
Szu JI, Obenaus A (2021) Cerebrovascular phenotypes in mouse models of Alzheimer's disease. J Cereb Blood Flow Metab 41:1821–1841
Nakajima M, Yuasa S, Ueno M, Takakura N, Koseki H, Shirasawa T (2003) Abnormal blood vessel development in mice lacking presenilin-1. Mech Dev 120:657–667
Janota CS, Brites D, Lemere CA, Brito MA (2015) Glio-vascular changes during ageing in wild-type and Alzheimer's disease-like APP/PS1 mice. Brain Res 1620:153–168
Oh ES, Savonenko AV, King JF, Fangmark Tucker SM, Rudow GL, Xu G et al (2009) Amyloid precursor protein increases cortical neuron size in transgenic mice. Neurobiol Aging 30:1238–1244
Tarasoff-Conway JM, Carare RO, Osorio RS, Glodzik L, Butler T, Fieremans E et al (2015) Clearance systems in the brain-implications for Alzheimer disease. Nat Rev Neurol 11:457–470
Kwon HS, Koh SH (2020) Neuroinflammation in neurodegenerative disorders: the roles of microglia and astrocytes. Translational Neurodegeneration 9:42
Kaur D, Sharma V, Deshmukh R (2019) Activation of microglia and astrocytes: a roadway to neuroinflammation and Alzheimer's disease. Inflammopharmacology 27:663–677
Lopez-Rodriguez AB, Hennessy E, Murray CL, Nazmi A, Delaney HJ, Healy D et al (2021) Acute systemic inflammation exacerbates neuroinflammation in Alzheimer's disease: IL-1β drives amplified responses in primed astrocytes and neuronal network dysfunction. Alzheimers Dement 17:1735–1755
Lok K, Zhao H, Shen H, Wang Z, Gao X, Zhao W et al (2013) Characterization of the APP/PS1 mouse model of Alzheimer's disease in senescence accelerated background. Neurosci Lett. ;557 Pt B:84 – 9.
Gallagher JJ, Minogue AM, Lynch MA (2013) Impaired performance of female APP/PS1 mice in the Morris water maze is coupled with increased Abeta accumulation and microglial activation. Neurodegener Dis 11:33–41
Jiao SS, Bu XL, Liu YH, Zhu C, Wang QH, Shen LL et al (2016) Sex Dimorphism Profile of Alzheimer's Disease-Type Pathologies in an APP/PS1 Mouse Model. Neurotox Res 29:256–266
Xiong H, Callaghan D, Wodzinska J, Xu J, Premyslova M, Liu QY et al (2011) Biochemical and behavioral characterization of the double transgenic mouse model (APPswe/PS1dE9) of Alzheimer's disease. Neurosci Bull 27:221–232
Lopez OL, Kuller LH (2019) Epidemiology of aging and associated cognitive disorders: Prevalence and incidence of Alzheimer's disease and other dementias. Handb Clin Neurol 167:139–148
Niu H, Alvarez-Alvarez I, Guillen-Grima F, Aguinaga-Ontoso I (2017) Prevalence and incidence of Alzheimer's disease in Europe: A meta-analysis. Neurologia 32:523–532
Yang CZ, Wang SH, Zhang RH, Lin JH, Tian YH, Yang YQ et al (2023) Neuroprotective effect of astragalin via activating PI3K/Akt-mTOR-mediated autophagy on APP/PS1 mice. Cell Death Discov 9:15
Qian X, Hai W, Chen S, Zhang M, Jiang X, Tang H (2023) Multi-omics data reveals aberrant gut microbiota-host glycerophospholipid metabolism in association with neuroinflammation in APP/PS1 mice. Gut Microbes 15:2282790
Gao X, Yu X, Zhang C, Wang Y, Sun Y, Sun H et al (2022) Telomeres and Mitochondrial Metabolism: Implications for Cellular Senescence and Age-related Diseases. Stem Cell Rev Rep 18:2315–2327
Butterfield DA, Halliwell B (2019) Oxidative stress, dysfunctional glucose metabolism and Alzheimer disease. Nat Rev Neurosci 20:148–160
Zhang Y, Liu X, Wiggins KL, Kurniansyah N, Guo X, Rodrigue AL et al (2023) Association of Mitochondrial DNA Copy Number With Brain MRI Markers and Cognitive Function: A Meta-analysis of Community-Based Cohorts. Neurology 100:e1930–e43
Hou Y, Wei Y, Lautrup S, Yang B, Wang Y, Cordonnier S et al (2021) NAD(+) supplementation reduces neuroinflammation and cell senescence in a transgenic mouse model of Alzheimer's disease via cGAS-STING. Proc Natl Acad Sci U S A. ;118

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You are reading this latest preprint version

Dysplasia of cortical capillaries as the origin of Alzheimer’s disease: experimental evidence from APP/PS1

Status:

Version 1

Abstract

Figures

Highlights

Background

Methods

Animals

Tissue collection

Protein extraction

ELISA quantitation

Behavior experiments

Immunofluorescence Staining

Quantification of micro-vessels

RNA-Seq of mouse capillary

RNA-Seq in AD Patients

Aβ₁₋₄₂ Oligomers on cells

RNA extraction and quantitative PCR

Statistical analysis

Results

Decreased autonomic activity and increased memory loss in 9 months APP/PS1 mice

Neuron apoptosis increased in 6-month-old APP/PS1 mice

The levels of inflammation factors increased at APP/PS1 mice

Activated astrocytes surrounded capillaries in 1-month-old and increased with aging in APP/PS1 mice

Cortical vascular dysplasia starting in 1-month-old and endothelial cell apoptosis increased at 3-month-old APP/PS1 mice

Vascular energy metabolism deficit and Neovascular Weakness in early AD

Aβ oligomers promote angiogenesis at low doses, inhibit at high doses

Discussion

Conclusions

Abbreviations

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

Dysplasia of cortical capillaries as the origin of Alzheimer’s disease: experimental evidence from APP/PS1

Status:

Version 1

Abstract

Figures

Highlights

Background

Methods

Animals

Tissue collection

Protein extraction

ELISA quantitation

Behavior experiments

Immunofluorescence Staining

Quantification of micro-vessels

RNA-Seq of mouse capillary

RNA-Seq in AD Patients

Aβ1−42 Oligomers on cells

RNA extraction and quantitative PCR

Statistical analysis

Results

Decreased autonomic activity and increased memory loss in 9 months APP/PS1 mice

Neuron apoptosis increased in 6-month-old APP/PS1 mice

The levels of inflammation factors increased at APP/PS1 mice

Activated astrocytes surrounded capillaries in 1-month-old and increased with aging in APP/PS1 mice

Cortical vascular dysplasia starting in 1-month-old and endothelial cell apoptosis increased at 3-month-old APP/PS1 mice

Vascular energy metabolism deficit and Neovascular Weakness in early AD

Aβ oligomers promote angiogenesis at low doses, inhibit at high doses

Discussion

Conclusions

Abbreviations

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1

Aβ₁₋₄₂ Oligomers on cells