AD Mice Research Articles

Eugenol relieves the pathological manifestations of Alzheimer's disease in 5×FAD mice

BackgroundAlzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the accumulation of amyloid-β (Aβ) and excessive neuroinflammation, resulting in neuronal cell death and cognitive impairments. Eugenol, a phenylpropene, is the main component of Syzygium aromaticum L. (Myrtaceae) and has multiple therapeutic effects, including neuroprotective and anti-inflammatory effects, through multimodal mechanisms. PurposeWe aimed to investigate the effect of eugenol on AD pathologies using a 5× familiar AD (5×FAD) mouse model. MethodsEight-month-old 5×FAD and wild-type mice were administered with eugenol (10 or 30 mg/kg/day, p.o) for 2 months. Y-maze and Morris water maze tests were performed to assess the cognitive function of mice. After the behavioral test, molecular analysis was conducted to investigate the therapeutic mechanism of eugenol. ResultsOur findings indicate that eugenol treatment effectively mitigated cognitive impairments in 5×FAD mice. This beneficial effect was associated with a decrease in AD pathologies, including neuronal cell loss and Aβ deposition. Specifically, eugenol inhibited necroptosis activation and increased microglial phagocytosis, which were the underlying mechanisms for the observed reductions in neuronal cell loss and Aβ deposition, respectively. ConclusionOverall, our data suggest that eugenol would be a potential therapeutic candidate for AD.

IGF‐I modulation of emotion and social interaction through Locus Coeruleus in aging and AD mice

AbstractBackgroundInsulin‐like Growth Factor I (IGF‐I) is a peptide involved in many processes in the brain. Recently, we described how IGF‐I modulates sleep behavior, response to stress, and its role in cognition through cholinergic, orexinergic, and locus coeruleus nuclei. Nonetheless, IGF‐I modulation of social behavior remains explored, especially during aging and Alzheimer’s disease pathology. This study aims to determine how IGF‐I modulates emotion and social behavior through Locus Coeruleus activity in young (<6m), middle‐aged (<12m, and old control (>18m), transgenic APP/PS1 and DPS‐4 mice, from the same ages.MethodWe use extensive behavioral testing of cognition (Y Maze spontaneous activity) and emotion (Forced Swim Test, Elevated Plus Maze), social interaction (Social affiliation and social novelty/Preference), and another test. We also use electrophysiology to determine LC responses to IGF‐I as DPS‐4 neurotoxin to evaluate the role of LC in emotion and social interaction.ResultsWe now report that social behavior is reduced through aging in control mice, even after the cognitive decline. Moreover, APP/PS1 present similar social interaction alterations to old C57 mice (>18m). Further, the activation of electrically stimulated LH neurons by local IGF‐I in young mice was reduced in middle‐aged and aged mice. Middle‐age C57 mice injected with DSP‐4 mice and APP/PS1 present disrupted social behavior and LC activity.ConclusionConsequently, IGF‐I can activate and modulate LC responses with our results. Social and emotional disturbances may be related to IGF‐I resistance in LC, reflecting a broader loss of IGF‐I activity in the aged mouse brain.

Continuous wave 670nm LED light therapy improves short‐ and long‐term object recognition, locomotion, and reduces phosphorylated tau burden in 3xTgAD mice

AbstractBackgroundPhotobiomodulation (PBM) therapy uses 620‐1100nm red to near‐infrared light to modulate biological processes including neuroinflammation, amyloid and tau oligomerization, and apoptosis. We have shown that 670nm light therapy reduces synaptic vulnerability to amyloid‐β oligomers in wild‐type (WT) mice and reduces tau oligomerization in mouse models of tauopathy. Here we sought to determine if 670nm light therapy could rescue cognitive and motor dysfunction and reduce tau hyperphosphorylation in 14‐to‐18‐month‐old 3xTgAD mice.Method14‐to‐18‐month‐old 3xTgAD mice were treated with continuous‐wave 670nm LED light applied directly to the head for 90s per day, 5 days per week for 4 weeks. 3xTgAD sham and WT controls were held under the LED device with the light turned off for the same amount of time. During the fourth week of treatment, spontaneous locomotor behavior was measured by placing animals in an empty chamber for 10 minutes using ANY‐maze software to track mobility data. Animals were then tested for working memory in the Y maze spontaneous alternation task and short‐and long‐term memory in the novel object recognition task. At the completion of behavioral testing on treatment day 20, brains were collected for western blot analysis of total tau and phospho‐tau (pTau).ResultLight‐treated 3xTgAD mice showed increased distance traveled compared to sham (17.43 ± 3.46 vs. 9.97 ± 3.03, one‐way ANOVA p = 0.03), and decreased immobile episodes (4.50 ± 1.92 vs 10.00 ± 1.83, one‐way ANOVA p = 0.02) in the spontaneous locomotor activity test. Light‐treated animals also showed significant object recognition at 2 hours (DI 32.75 ± 7.71, one sample t‐test p<0.001) and 24 hours (DI 44.14 ± 15.73, one sample t‐test p = 0.001) post‐training. Light treatment also reduced the ratio of hippocampal pTau/Tau in 3xTg AD mice as compared to sham (0.11 ± 0.05 vs. 0.32 ± 0.13, one‐way ANOVA p = 0.04).ConclusionHere we show rescue of locomotor behavior and cognitive dysfunction, and reduction of Tau phosphorylation in the hippocampus of 3xTgAD mice using a non‐invasive transcranial treatment with 670nm LED light. Our data suggest that treatment with 670nm red light could significantly improve cognitive function in AD patients and reduce hyperphosphorylation of tau thus possibly preventing further neurodegeneration.

Theta‐Gamma Phase‐Amplitude Coupling Deficit in Streptozotocin AD Rat Model

AbstractBackgroundTheta rhythms are known to encode sensory information and reflect their effect into gamma oscillations through a modulation process known as theta‐gamma phase‐amplitude coupling (PAC) (Amemiya et al., Cell Reports 2018). The role of the PAC as a network‐level indicator of cognitive impairment in disorders such as dementia and Alzheimer’s disease has received much attention recently (Zheng et al. Nature communication 2020).Injection of Streptozotocin (STZ) in animals is reported to cause resistance to insulin uptake in the brain, leading to memory and cognitive impairment (Kamat, Neural Regeneration Research 2015). The current study examines the induced deficit in the PAC as an early indicator of neurodegenerative effects of STZ.Method3 adult male Wistar rats were included in this study (270 – 300 g). Intraventricular injection of STZ was performed at a dose of 3 mg / Kg with a volume of 10 μl. Two stainless steel electrodes were implanted in the hippocampus (CA1) and medial prefrontal cortex (mPFC). The rats were free to move during recording. LFP data were recorded and segmented into windows of 20 s. Preprocessing and noisy trial rejection were employed for artifact removal, and the theta‐gamma PAC was measured using the mean vector length (tf‐MVL) method (Munia et al., Scientific Reports 2019).ResultOne week after STZ injection, the theta‐gamma PAC values did not show a significant change but after two weeks variation was observed. During this period, the power of different frequency bands was also measured and no significant change was observed even after two weeks. Theta‐gamma PAC deficiency was observed in both regions (CA1 and mPFC).ConclusionSTZ’s intracerebro‐ventricular injection is known to produce cognitive deficits along with an increase in Aβ deposition. This study reports that cross‐frequency coupling deficiency is also observed in this AD mouse model. Moreover, the PAC deficit was detected earlier than any change was observed in the spectral analysis of the data, suggesting that it can serve as a diagnosis tool for memory impairment due to neurodegeneration in the STZ mouse model of AD.

The neuroprotective N-terminal amyloid-β core hexapeptide reverses reactive gliosis and gliotoxicity in Alzheimer’s disease pathology models

BackgroundAlzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by accumulation of extracellular amyloid beta (Aβ) and intracellular neurofibrillary tangles, leading to chronic activation of astrocytes and microglia and persistent neuroinflammation. Aβ-linked activation of microglia and astrocytes leads to increased intracellular calcium and production of proinflammatory cytokines, impacting the progression of neurodegeneration. An N-terminal Aβ fragment (Aβ1–15) and a shorter hexapeptide core sequence within the N-Aβ fragment (N-Aβcore: Aβ10–15) have previously been shown to protect against Aβ-induced mitochondrial dysfunction, oxidative stress and apoptosis in neurons and rescue synaptic and spatial memory deficits in an APP/PSEN1 mouse model. Here, we hypothesized that the N-Aβ fragment and N-Aβcore are protective against Aβ-induced gliotoxicity, promoting a neuroprotective environment and potentially alleviating the characteristically persistent neuroinflammation present in AD.MethodsWe treated ex vivo organotypic brain slice cultures from an aged familial AD mouse model, 5xFAD, with the N-Aβcore and used immunocytochemistry to assess the impact on astrogliosis and microgliosis and alterations in synaptophysin-positive puncta engulfed by microglia. Isolated neuron/glia cultures, mixed glial cultures or a microglial cell line were treated with oligomeric human Aβ at concentrations mimicking the pathogenic concentrations (μM) observed in AD in the absence or presence of the non-toxic N-terminal Aβ fragments. Resultant changes in synaptic density, gliosis, oxidative stress, mitochondrial dysfunction, apoptosis, and the expression and release of proinflammatory markers were then determined.ResultsWe demonstrate that the N-terminal Aβ fragments mitigated the phenotypic switch leading to astrogliosis and microgliosis induced by pathological concentrations of Aβ in mixed glial cultures and organotypic brain slice cultures from the transgenic 5xFAD mouse model, while protecting against Aβ-induced oxidative stress, mitochondrial dysfunction and apoptosis in isolated astrocytes and microglia. Moreover, the addition of the N-Aβcore attenuated the expression and release of proinflammatory mediators in microglial cells activated by Aβ and rescued microglia-mediated loss of synaptic elements induced by pathological levels of Aβ.ConclusionsTogether, these findings indicate the protective functions of the N-terminal Aβ fragments extend to reactive gliosis and gliotoxicity induced by Aβ, by preventing or reversing glial reactive states indicative of neuroinflammation and synaptic loss central to AD pathogenesis.

Sennoside A restrains TRAF6 level to modulate ferroptosis, inflammation and cognitive impairment in aging mice with Alzheimer's Disease

BackgroundAlzheimer's disease (AD) is a common neurodegenerative disease and a momentous cause of dementia in the elderly. Sennoside A (SA) is an anthraquinone compound and possesses decisive protective functions in various human diseases. The purpose of this research was to elucidate the protective effect of SA against AD and investigate its mechanism. MethodsMale APPswe/PS1dE9 (APP/PS1) transgenic mice with a C57BL/6J background were chosen as AD model. Age-matched nontransgenic littermates (C57BL/6 mice) were negative controls. SA's functions in AD in vivo were estimated by cognitive function analysis, Western blot, hematoxylin-eosin staining, TUNEL staining, Nissl staining, detection of Fe2+ levels, glutathione and malondialdehyde contents, and quantitative real-time PCR. Also, SA's functions in AD in LPS-induced BV2 cells were examined using Cell Counting Kit-8 assay, flow cytometry, quantitative real-time PCR, Western blot, enzyme-linked immunosorbent assay, and analysis of reactive oxygen species levels. Meanwhile, SA's mechanisms in AD were assessed by several molecular experiments. ResultsFunctionally, SA mitigated cognitive function, hippocampal neuronal apoptosis, ferroptosis, oxidative stress, and inflammation in AD mice. Furthermore, SA reduced BV2 cell apoptosis, ferroptosis, oxidative stress, and inflammation induced by LPS. Rescue assay revealed that SA abolished the high expressions of TRAF6 and p-P65 (NF-κB pathway-related proteins) induced by AD, and this impact was reversed after TRAF6 overexpression. Conversely, this impact was further enhanced after TRAF6 knockdown. ConclusionsSA relieved ferroptosis, inflammation and cognitive impairment in aging mice with AD through decreasing TRAF6.

Structural-Activity Relationship of Rare Ginsenosides from Red Ginseng in the Treatment of Alzheimer's Disease.

Rare ginsenosides are the major components of red ginseng. However, there has been little research into the relationship between the structure of ginsenosides and their anti-inflammatory activity. In this work, BV-2 cells induced by lipopolysaccharide (LPS) or nigericin, the anti-inflammatory activity of eight rare ginsenosides, and the target proteins expression of AD were compared. In addition, the Morris water maze test, HE staining, thioflavins staining, and urine metabonomics were used to evaluate the effect of Rh4 on AD mice. Our results showed that their configuration influences the anti-inflammatory activity of ginsenosides. Ginsenosides Rk1, Rg5, Rk3, and Rh4 have significant anti-inflammatory activity compared to ginsenosides S-Rh1, R-Rh1, S-Rg3, and R-Rg3. Ginsenosides S-Rh1 and S-Rg3 have more pronounced anti-inflammatory activity than ginsenosides R-Rh1 and R-Rg3, respectively. Furthermore, the two pairs of stereoisomeric ginsenosides can significantly reduce the level of NLRP3, caspase-1, and ASC in BV-2 cells. Interestingly, Rh4 can improve the learning ability of AD mice, improve cognitive impairment, reduce hippocampal neuronal apoptosis and Aβ deposition, and regulate AD-related pathways such as the tricarboxylic acid cycle and the sphingolipid metabolism. Our findings conclude that rare ginsenosides with a double bond have more anti-inflammatory activity than those without, and 20(S)-ginsenosides have more excellent anti-inflammatory activity than 20(R)-ginsenosides.

Most dystrophic neurites in the common 5xFAD Alzheimer mouse model originate from axon terminals

How dystrophic neurites form around amyloid plaques is a key aspect of understanding the early pathophysiology of Alzheimer's disease. At present, three hypotheses prevail: (1) dystrophies result from extracellular amyloid-beta (Aβ) toxicity; (2) dystrophies results from accumulation of Aβ into distal neurites; and (3) dystrophies represent blebbing of the somatic membrane of a neuron with high Aβ load. We utilized a unique feature of the common 5xFAD AD mouse model to test these hypotheses. Cortical layer 5 pyramidal neurons show intracellular APP and Aβ accumulation before amyloid plaque formation while dentate granule cells in these mice show no APP accumulation at any age. However, the dentate gyrus shows amyloid plaques by 3 months of age. By a careful confocal microscopic analysis we found no evidence of severe degeneration in amyloid laden layer 5 pyramidal neurons in contrast to hypothesis 3. Using injecting red fluorescent marker into lateral entorhinal projection neurons in 5xFAD mice with endogenous green fluorescent protein (GFP) in dentate granule cells we could demonstrate that all dystrophies is outer molecular layer originate from the axon terminal of entorhinal projection neurons. Immunostaining with vesicular glutamate transporter supported the axonal nature of the dystrophies in the acellular dentate molecular layer. We observed few small dystrophies in the GFP labeled granule cell dendrites. In general GFP labeled dendrites appear normal around the amyloid plaques. These findings favor hypothesis 2 as the most likely mechanism of dystrophic neurite formation.

Dihydromyricetin suppresses inflammatory injury in microglial cells to improve neurological behaviors of Alzheimer's disease mice via the TLR4/MD2 signal.

We analyzed the role and mechanism of dihydromyricetin (DHM) in suppressing inflammatory injury in microglial cells via targeting MD2. In vitro, BV2 cells were used as the objects of study to induce inflammatory injury with LPS+ATP, then the cell apoptosis level was identified, inflammatory factor levels were measured by ELISA, TLR4 and MD2 were stained with fluorescence staining, and protein expression was determined using Western-blot (WB) assay. Afterwards, MD2 expression was knocked down n BV2 cells to construct the BV2-MD2-/- cell line, so as to detect the role of DHM on BV2-MD2-/-. Moreover, the binding of DHM to MD2 was analyzed via mall molecule-protein docking and pull-down assays. In-vivo, wild-type (WT) C67BL/6 mice and APP/PS1 (AD) mice were used as the objects of study, which were intervened with DHM to detect the changes in mouse cognition. In addition, the pathological changes of brain tissues were analyzed with H&E staining. In addition, the inflammatory factor and protein levels in brain tissues were also detected. DHM suppressed inflammatory injury in BV2 cells, reduced the cell apoptosis rate and inflammatory factor levels, and suppressed the level of TLR4 and MD2. After MD2 knockdown, DHM was unable to further suppress BV2 cell injury. Results of small molecule-protein docking and pull-down assays suggested that DHM bound to MD2 to suppress the formation of TLR4 complex. In AD mice, DHM improved the cognitive disorder in mice, suppressed inflammatory injury in brain tissues and lowered the expression of TLR4 protein. DHM targeted MD2 to suppress the formation of TLR4 protein complex, thereby suppressing inflammatory injury in microglial cells and improving the cognition in AD mice.

Allelic effects on cerebral and carotid artery passive mechanical properties in young, adult, and aged hAPOE3 and hAPOE4 mice

Alzheimer’s disease (AD) is the most common form of dementia and among the leading mortalities in the US. There is growing evidence supporting a connection between AD and cardiovascular disease (CVD). Variant isoforms of apolipoprotein E (APOE) are risk factors for AD and CVD. Compared to the most common APOE isoform, APOE3 (E3), APOE4 (E4) increases AD risk. In order to study APOE-mediated processes, posterior cerebral arteries (PCA) and common carotid arteries (CCA) were isolated from mice expressing human-ApoE targeted replacement of APOE3 (B6.129P2- Apoe tm2(APOE*3)Mae N8) and APOE4 (B6.129P2- Apoe tm3(APOE*4)Mae N8)(Taconic Labs). Our objective was to determine whether the E3 and E4 allele cause different mechanical properties in the absence of extracellular Ca 2+ in the PCA and CCA isolated from young (Y, 3-4mo), adult (Ad, 12-15mo), and aged (Ag, 18-22mo), homozygous E3 and E4, male and female mice. We hypothesized that E4 would alter PCA and CCA structure/function when compared to age matched E3 cohorts. 5-8mm segments of PCA and CCA were isolated, cleaned of connective tissue, cannulated, and placed into an arteriograph. Upon equilibration, all vessels were challenged with 60mM [K + ] to assess viability. Vessels not responding to 60mM [K + ] were discarded. Mechanical characteristics, including lumen diameter (LD), wall thickness (WT), passive distensibility (PD), and stress/strain (S/S) were measured at intraluminal pressures ranging from 10-140mmHg. We observed no statistical differences in LD, PD, or S/S in PCAs and CCAs of Y and Ad, E3 and E4 mice. For LD and WT, Ag E3 was greater than Ag E4 (p<0.05). In contrast, LD in PCAs and CCAs of Ag E3 mice was larger than in Ag E4 mice (p<0.05). We further observed that PD and S/S in CCAs from Ag E3 was greater than in Ag E4 mice (p<0.05), whereas there was no difference in PD and S/S in PCAs isolated from Ag E3 or E4 mice. The WT of PCA in Y E4 was significantly greater than Y E3 mice (p<0.05). In contrast, WT in Ag E3 mice was larger than Ag E4 mice (p<0.05). There was no difference between WT of Ad E3 and E4 mice. The WT of CCAs was significantly greater in Ag E3 vs Ag E4 mice (p<0.05). There is no difference in WT in CCAs from Y (E3 vs E4) or Ad (E3 vs E4) mice. This data indicates aging has minimal effect on mechanical properties in the PCA. In contrast, CCAs in Ag E4 exhibited greater arterial stiffening as indicated by a decrease in their distensibility and leftward shift in S/S, as evidenced by greater stress for given amount of strain observed in PCAs of Ag E4 mice at increased intraluminal pressures. ABRC/ADHS18-205211 (JVE, TBJ, CBJ, DME), Arizona Alzheimer's Consortium (funded by the Arizona Department of Health Services, Contract No. CTR040636) and matching funds from Midwestern University (DME), Biomedical Sciences Program (BG, LJS, DME), Biomedical Sciences Start-up Funds (DME). LJS and ASH equally contributed as first authors. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Monitoring Subtle Changes of Blood-Brain Barrier Permeability via Detection of MiRNA-155 in Brain Microvasculature.

The changes of blood-brain barrier (BBB) permeability need to be sensitively reported when purposefully regulating the BBB or during some brain diseases. Currently available techniques for assessment of BBB integrity all suffer from limited sensitivity and only report serious BBB damage. Here, a targeted activatable nanoprobe is created to monitor subtle changes of BBB permeability by detecting the expression levels of BBB permeability-related miRNA (miRNA-155) in brain microvessel endothelial cells (BMECs). The probe is fabricated by coating the BMEC membrane on calcium phosphate (CaP)-mineralized metal-organic framework (MOF) nanoparticles loaded with hybridization chain reaction (HCR) probes. The coating of the BMEC membrane endows the nanoprobe with homologous targeting ability to BBB, and HCR probes released and escaped from lysosomes can be specifically lightened by miRNA-155. The activatable nanoprobe is able to monitor BBB permeability in inflammatory and AD mice. This work provides a new idea for highly sensitive evaluation of the BBB permeability, which has guiding significance in regulating BBB and formulating targeted therapeutic strategies.

Lupeol alleviates atopic dermatitis-like skin inflammation in 2,4-dinitrochlorobenzene/Dermatophagoides farinae extract-induced mice

BackgroundAtopic dermatitis (AD) is a chronic inflammatory skin disease that affects from children to adults widely, presenting symptoms such as pruritus, erythema, scaling, and dryness. Lupeol, a pentacyclic triterpenoid, has anti-inflammatory and antimicrobial activities. Based on these properties, the therapeutic effects of lupeol on skin disorders have been actively studied. In the present study, we aimed to determine the effectiveness of lupeol on AD.MethodsWe utilized tumor necrosis factor (TNF)-α/interferon (IFN)-γ-stimulated keratinocytes and 2, 4-dinitrochlorobenzene/Dermatophagoides farinae extract (DFE)-induced AD mice to confirm the action.ResultsLupeol inhibited TNF-α/IFN-γ-stimulated keratinocytes activation by reducing the expressions of pro-inflammatory cytokines and chemokines which are mediated by the activation of signaling molecules such as signal transducer and activator of transcription 1, mitogen-activated protein kinases (p38 and ERK), and nuclear factor-κB. Oral administration of lupeol suppressed epidermal and dermal thickening and immune cell infiltration in ear tissue. Immunoglobulin (Ig) E (total and DFE-specific) and IgG2a levels in serum were also reduced by lupeol. The gene expression and protein secretion of T helper (Th) 2 cytokines, Th1 cytokines, and pro-inflammatory cytokine in ear tissue were decreased by lupeol.ConclusionsThese results suggest that lupeol has inhibitory effects on AD-related responses. Therefore, lupeol could be a promising therapeutic agent for AD.

Reduced levels of NGF shift astrocytes toward a neurotoxic phenotype.

Nerve growth factor (NGF) is critical for neuronal physiology during development and adulthood. Despite the well-recognized effect of NGF on neurons, less is known about whether NGF can actually affect other cell types in the central nervous system (CNS). In this work, we show that astrocytes are susceptible to changes in ambient levels of NGF. First, we observe that interfering with NGF signaling in vivo via the constitutive expression of an antiNGF antibody induces astrocytic atrophy. A similar asthenic phenotype is encountered in an uncleavable proNGF transgenic mouse model (TgproNGF#72), effectively increasing the brain proNGF levels. To examine whether this effect on astrocytes is cell-autonomous, we cultured wild-type primary astrocytes in the presence of antiNGF antibodies, uncovering that a short incubation period is sufficient to potently and rapidly trigger calcium oscillations. Acute induction of calcium oscillations by antiNGF antibodies is followed by progressive morphological changes similar to those observed in antiNGF AD11 mice. Conversely, incubation with mature NGF has no effect on either calcium activity nor on astrocytic morphology. At longer timescales, transcriptomic analysis revealed that NGF-deprived astrocytes acquire a proinflammatory profile. In particular, antiNGF-treated astrocytes show upregulation of neurotoxic transcripts and downregulation of neuroprotective mRNAs. Consistent with that data, culturing wild-type neurons in the presence of NGF-deprived astrocytes leads to neuronal cell death. Finally, we report that in both awake and anesthetized mice, astrocytes in layer I of the motor cortex respond with an increase in calcium activity to acute NGF inhibition using either NGF-neutralizing antibodies or a TrkA-Fc NGF scavenger. Moreover, in vivo calcium imaging in the cortex of the 5xFAD neurodegeneration mouse model shows an increased level of spontaneous calcium activity in astrocytes, which is significantly reduced after acute administration of NGF. In conclusion, we unveil a novel neurotoxic mechanism driven by astrocytes, triggered by their sensing and reacting to changes in the levels of ambient NGF.

Differential and substrate-specific inhibition of γ-secretase by the C-terminal region of ApoE2, ApoE3, and ApoE4

Aberrant low γ-secretase activity is associated with most of the presenilin mutations that underlie familial Alzheimer's disease (fAD). However, the role of γ-secretase in the more prevalent sporadic AD (sAD) remains unaddressed. Here, we report that human apolipoprotein E (ApoE), the most important genetic risk factor of sAD, interacts with γ-secretase and inhibits it with substrate specificity in cell-autonomous manners through its conserved C-terminal region (CT). This ApoE CT-mediated inhibitory activity is differentially compromised in different ApoE isoforms, resulting in an ApoE2>ApoE3>ApoE4 potency rank order inversely correlating to their associated AD risk. Interestingly, in an AD mouse model, neuronal ApoE CT migrates to amyloid plaques in the subiculum from other regions and alleviates the plaque burden. Together, our data reveal a hidden role of ApoE as a γ-secretase inhibitor with substrate specificity and suggest that this precision γ-inhibition by ApoE may protect against the risk of sAD.

900 MHZ electromagnetic field exposure relieved AD-like symptoms on APP/PS1 mice: A potential non-invasive strategy for AD treatment

BackgroundEvidence shows that microwaves radiation may have various biological effects on central nervous system. Role of electromagnetic fields in neurodegenerative diseases, especially AD, has been widely studied, but results of these studies are inconsistent. Therefore, the above effects were verified again and the mechanism was preliminarily discussed. MethodsAmyloid precursor protein (APP/PS1) and WT mice were exposed to long-term microwave radiation for 270 days (900 MHz, SAR: 0.25–1.055 W/kg, 2 h/day, alternately), and related indices were assessed at 90, 180 and 270 days. Cognition was evaluated by Morris water maze, Y maze and new object recognition tests. Congo red staining, immunohistochemistry and ELISA were used to analyze Aβ plaques, Aβ40 and Aβ42 content. Differentially expressed proteins in hippocampus between microwave-exposed and unexposed AD mice were identified by proteomics. ResultsSpatial and working memory was improved in AD mice after long-term 900 MHz microwave exposure compared with after sham exposure. Microwave radiation (900 MHz) for 180 or 270 days did not induce Aβ plaque formation in WT mice but inhibited Aβ accumulation in the cerebral cortex and hippocampus in 2- and 5-month-old APP/PS1 mice. This effect mainly occurred in the late stage of the disease and may have been attributed to downregulation of apolipoprotein family member and SNCA expression and excitatory/inhibitory neurotransmitter rebalance in the hippocampus. ConclusionsThe present results indicated that long-term microwave radiation can retard AD development and exert a beneficial effect against AD, suggesting that 900 MHz microwave exposure may be a potential therapy for AD.

Targeting lncRNA NEAT1 Impedes Alzheimer’s Disease Progression via MicroRNA-193a Mediated CREB/BDNF and NRF2/NQO1 Pathways

AbstractBackgroundLong noncoding RNA nuclear-enriched abundant transcript 1 (lnc-NEAT1) is closely implicated in neurological or degenerative diseases, while its implication in AD is rarely reported. This study aimed to investigate the effect of lnc-NEAT1 knockdown on neuron injury, inflammation, and oxidative stress in AD, as well as its interaction with downstream targets and pathways.MethodsAPPswe/PS1dE9 transgenic mice were injected with negative control or lnc-NEAT1 interference lentivirus. Besides, AD cellular model was constructed by amyloid β treatment in mice primary neuron cells; then, knockdown of lnc-NEAT1 and microRNA-193a (miR-193a) was performed alone or in combination.ResultsIn vivo experiments revealed that Lnc-NEAT1 knockdown improved cognition in AD mice reflected by Morrison water maze and Y-maze assays. Besides, lnc-NEAT1 knockdown reduced injury and apoptosis, decreased TNF-α and IL-1β levels (indicating lower inflammation level), repressed ROS, MDA but promoted ATP and SOD levels (suggesting lower oxidative stress level), and activated CREB/BDNF and NRF2/NQO1 pathways in hippocampi of AD mice. Notably, lnc-NEAT1 down-regulated miR-193a both in vitro and in vivo; also, it acted as a decoy of miR-193a. In vitro experiments showed that lnc-NEAT1 knockdown decreased apoptosis and oxidative stress, improved cell viability, and also activated CREB/BDNF and NRF2/NQO1 pathways in AD cellular model. Meanwhile, miR-193a knockdown showed the opposite effects, which also attenuated lnc-NEAT1 knockdown-mediated reduction in injury, oxidative stress, and activation of CREB/BDNF and NRF2/NQO1 pathways of AD cellular model.ConclusionLnc-NEAT1 knockdown reduces neuron injury, inflammation, and oxidative stress through activating miR-193a mediated CREB/BDNF and NRF2/NQO1 pathways in AD.FundingNo Funding

Calcium Folate Nanoparticles as Dual‐Functional Neural Inducing Factors to Promote the Differentiation of Neural Stem Cells into Cholinergic Neurons

AbstractAlzheimer's disease (AD) features the loss of cholinergic neurons in the mesopontine area. There is no available approach to repair the damaged cholinergic neurons. Neural stem cell (NSC)‐based therapy is a promising strategy for the treatment of AD. However, it is a challenge to direct the NSCs to specifically differentiate into cholinergic neurons. Herein, calcium folate (CaFO) nanoparticles are synthesized through a facile nanoprecipitation approach for promoting the differentiation of NSCs into functional cholinergic neurons. After uptake by NSCs, the CaFO nanoparticles are distributed in the lysosomes (pH< 5.5) and can be decomposed into Ca2+ and folic acid in the acidic environment. The Ca2+ can accelerate the differentiation rate of NSCs while the folic acid can direct the NSCs to differentiate into cholinergic neurons. The in vitro experiments demonstrate that under the stimulation of CaFO nanoparticles, the NSCs differentiate into functional cholinergic neurons within 5 d. Animal experiments prove that the CaFO nanoparticles also promote the neuronal differentiation of NSCs in vivo, leading to the improvement in the cognitive memory ability of AD mice. This study provides a new strategy to induce the quick differentiation of NSCs into functional cholinergic neurons, which is promising for the treatment of AD.

Whole-body vibration ameliorates glial pathological changes in the hippocampus of hAPP transgenic mice, but does not affect plaque load

BackgroundAlzheimer’s disease (AD) is the core cause of dementia in elderly populations. One of the main hallmarks of AD is extracellular amyloid beta (Aβ) accumulation (APP-pathology) associated with glial-mediated neuroinflammation. Whole-Body Vibration (WBV) is a passive form of exercise, but its effects on AD pathology are still unknown.MethodsFive months old male J20 mice (n = 26) and their wild type (WT) littermates (n = 24) were used to investigate the effect of WBV on amyloid pathology and the healthy brain. Both J20 and WT mice underwent WBV on a vibration platform or pseudo vibration treatment. The vibration intervention consisted of 2 WBV sessions of 10 min per day, five days per week for five consecutive weeks. After five weeks of WBV, the balance beam test was used to assess motor performance. Brain tissue was collected to quantify Aβ deposition and immunomarkers of astrocytes and microglia.ResultsJ20 mice have a limited number of plaques at this relatively young age. Amyloid plaque load was not affected by WBV. Microglia activation based on IBA1-immunostaining was significantly increased in the J20 animals compared to the WT littermates, whereas CD68 expression was not significantly altered. WBV treatment was effective to ameliorate microglia activation based on morphology in both J20 and WT animals in the Dentate Gyrus, but not so in the other subregions. Furthermore, GFAP expression based on coverage was reduced in J20 pseudo-treated mice compared to the WT littermates and it was significantly reserved in the J20 WBV vs. pseudo-treated animals. Further, only for the WT animals a tendency of improved motor performance was observed in the WBV group compared to the pseudo vibration group.ConclusionIn accordance with the literature, we detected an early plaque load, reduced GFAP expression and increased microglia activity in J20 mice at the age of ~ 6 months. Our findings indicate that WBV has beneficial effects on the early progression of brain pathology. WBV restored, above all, the morphology of GFAP positive astrocytes to the WT level that could be considered the non-pathological and hence “healthy” level. Next experiments need to be performed to determine whether WBV is also affective in J20 mice of older age or other AD mouse models.

Multivalent Nanobody Conjugate with Rigid, Reactive Oxygen Species Scavenging Scaffold for Multi-Target Therapy of Alzheimer's Disease.

Efficient therapeutic strategies that concurrently target both Aβ aggregation and oxidative stress in the Alzheimer'sdisease(AD)microenvironment emerge as a cutting-edge tool to combat the intricate pathogenesis of AD. Here, a multivalent nanobody conjugate with rigid, reactive oxygen species (ROS) scavenging scaffold is developed to achieve simultaneous Aβ amyloidogenesis mitigation, ROS elimination, and Aβ plaque clearance. Grafting Aβ segment (33-GLMVGGVVIA-42) into the third complementary-determining region of a parent nanobody generates an engineered nanobody NB that can recognize Aβ and inhibit its aggregation through homotypic interactions. NB is further genetically modified with a fragment of human interleukin-1β (163-VQGEESNDK-171), so that the obtained fusion nanobody NBIL can also facilitate the Aβ clearance by microglia. Linking NBIL covalently onto a rigid, ROS scavenging scaffold poly(deca-4,6-diynedioic acid) (PDDA) creates the multivalent nanobody conjugate PNBIL, which not only boosts the binding affinity between NBIL and Aβ aggregates for nearly 100 times but also possesses a long-term capability of oxidative stress alleviation, inflammation reduction, and neuron protection. PNBIL has significantly attenuated symptoms on two AD mouse models through amyloidogenesis inhibition and AD microenvironment modulation, validating that the multivalent nanobody conjugate design based on combinatory nanobody and molecular engineering is a promising approach of multi-target therapeutic strategies.

Attenuation of Alzheimer’s brain pathology in 5XFAD mice by PTH1-34, a peptide of parathyroid hormone

BackgroundAlzheimer’s disease (AD) and osteoporosis are two distinct diseases but often occur in the same patient. Their relationship remains poorly understood. Studies using Tg2576 AD animal model demonstrate bone deficits, which precede the brain phenotypes by several months, arguing for the independence of bone deficits on brain degeneration and raising a question if the bone deficits contribute to the AD development. To address this question, we investigated the effects of PTH1-34, a peptide of parathyroid hormone analog and a well-recognized effective anabolic therapy drug for patients with osteoporosis, on 5XFAD animal model.Methods5XFAD mice, an early onset β-amyloid (Aβ)-based AD mouse model, were treated with PTH1-34 intermittently [once daily injection of hPTH1–34 (50 μg/Kg), 5 days/week, starting at 2-month old (MO) for 2–3 month]. Wild type mice (C57BL/6) were used as control. The bone phenotypes were examined by microCT and evaluated by measuring serum bone formation and resorption markers. The AD relevant brain pathology (e.g., Aβ and glial activation) and behaviors were assessed by a combination of immunohistochemical staining analysis, western blots, and behavior tests. Additionally, systemic and brain inflammation were evaluated by serum cytokine array, real-time PCR (qPCR), and RNAscope.ResultsA reduced trabecular, but not cortical, bone mass, accompanied with a decrease in bone formation and an increase in bone resorption, was detected in 5XFAD mice at age of 5/6-month old (MO). Upon PTH1-34 treatments, not only these bone deficits but also Aβ-associated brain pathologies, including Aβ and Aβ deposition levels, dystrophic neurites, glial cell activation, and brain inflammatory cytokines, were all diminished; and the cognitive function was improved. Further studies suggest that PTH1-34 acts on not only osteoblasts in the bone but also astrocytes in the brain, suppressing astrocyte senescence and expression of inflammatory cytokines in 5XFAD mice.ConclusionsThese results suggest that PTH1-34 may act as a senolytic-like drug, reducing systemic and brain inflammation and improving cognitive function, and implicate PTH1-34’s therapeutic potential for patients with not only osteoporosis but also AD.