Immunotherapy of cerebrovascular amyloidosis in a transgenic mouse model

Cerebrovascular amyloidosis is caused by amyloid accumulation in walls of blood vessel walls leading to hemorrhagic stroke and cognitive impairment. Transforming growth factor-β1 (TGF-β1) expression levels correlate with the degree of cerebrovascular amyloid deposition in Alzheimer's disease (AD) and TGF-β1 immunoreactivity in such cases is increased along the cerebral blood vessels. Here we show that a nasally administered proteosome-based adjuvant activates macrophages and decreases vascular amyloid in TGF-β1 mice. Animals were nasally treated with a proteosome-based adjuvant on a weekly basis for 3 months beginning at age 13 months. Using magnetic resonance imaging (MRI) we found that while control animals showed a significant cerebrovascular pathology, proteosome-based adjuvant prevents further brain damage and prevents pathological changes in the blood-brain barrier. Using an object recognition test and Y-maze, we found significant improvement in cognition in the treated group. Our findings support the potential use of a macrophage immunomodulator as a novel approach to reduce cerebrovascular amyloid, prevent microhemorrhage, and improve cognition.     

TLR4 mutation reduces microglial activation,increases Aβ deposits and exacerbates cognitive deficits in a mouse model of Alzheimer's disease

Background

Amyloid plaques, a pathological hallmark of Alzheimer's disease (AD), are accompanied by activated microglia. The role of activated microglia in the pathogenesis of AD remains controversial: either clearing Aβ deposits by phagocytosis or releasing proinflammatory cytokines and cytotoxic substances. Microglia can be activated via toll-like receptors (TLRs), a class of pattern-recognition receptors in the innate immune system. We previously demonstrated that an AD mouse model homozygous for a loss-of-function mutation of TLR4 had increases in Aβ deposits and buffer-soluble Aβ in the brain as compared with a TLR4 wild-type AD mouse model at 14-16 months of age. However, it is unknown if TLR4 signaling is involved in initiation of Aβ deposition as well as activation and recruitment of microglia at the early stage of AD. Here, we investigated the role of TLR4 signaling and microglial activation in early stages using 5-month-old AD mouse models when Aβ deposits start.

Methods

Microglial activation and amyloid deposition in the brain were determined by immunohistochemistry in the AD models. Levels of cerebral soluble Aβ were determined by ELISA. mRNA levels of cytokines and chemokines in the brain and Aβ-stimulated monocytes were quantified by real-time PCR. Cognitive functions were assessed by the Morris water maze.

Results

While no difference was found in cerebral Aβ load between AD mouse models at 5 months with and without TLR4 mutation, microglial activation in a TLR4 mutant AD model (TLR4M Tg) was less than that in a TLR4 wild-type AD model (TLR4W Tg). At 9 months, TLR4M Tg mice had increased Aβ deposition and soluble Aβ42 in the brain, which were associated with decrements in cognitive functions and expression levels of IL-1β, CCL3, and CCL4 in the hippocampus compared to TLR4W Tg mice. TLR4 mutation diminished Aβ-induced IL-1β, CCL3, and CCL4 expression in monocytes.

Conclusion

This is the first demonstration of TLR4-dependent activation of microglia at the early stage of β-amyloidosis. Our results indicate that TLR4 is not involved in the initiation of Aβ deposition and that, as Aβ deposits start, microglia are activated via TLR4 signaling to reduce Aβ deposits and preserve cognitive functions from Aβ-mediated neurotoxicity.

     

The therapeutic potential of human umbilical cord blood-derived mesenchymal stem cells in Alzheimer's disease

The neuropathological hallmarks of Alzheimer's disease (AD) include the presence of extracellular amyloid-β peptide (Aβ) in the form of amyloid plaques in the brain parenchyma and neuronal loss. The mechanism associated with neuronal death by amyloid plaques is unclear but oxidative stress and glial activation has been implicated. Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) are being scrutinized as a potential therapeutic tool to prevent various neurodegenerative diseases including AD. However, the therapeutic impact of hUCB-MSCs in AD has not yet been reported. Here we undertook in vitro work to examine the potential impact of hUCB-MSCs treatment on neuronal loss using a paradigm of cultured hippocampal neurons treated with Aβ. We confirmed that hUCB-MSCs co-culture reduced the hippocampal apoptosis induced by Aβ treatment. Moreover, in an acute AD mouse model to directly test the efficacy of hUCB-MSCs treatment on AD-related cognitive and neuropathological outcomes, we demonstrated that markers of glial activation, oxidative stress and apoptosis levels were decreased in AD mouse brain. Interestingly, hUCB-MSCs treated AD mice demonstrated cognitive rescue with restoration of learning/memory function. These data suggest that hUCB-MSCs warrant further investigation as a potential therapeutic agent in AD.     

Liver X receptor activation restores memory in aged AD mice without reducing amyloid

Alterations in cerebral cholesterol metabolism are thought to play a role in the progression of Alzheimer's disease (AD). Liver X receptors (LXRs) are key regulators of cholesterol metabolism. The synthetic LXR activator, T0901317 has been reported to improve memory functions in animal models for AD and to reduce amyloid-β (Aβ) deposition in the brain. Here we provide evidence that long-term administration of T0901317 to aged, 21-month-old APPSLxPS1mut mice restores impaired memory. Cerebral cholesterol turnover was enhanced as indicated by the increased levels of brain cholesterol precursors and the upregulation of LXR-target genes Abca1, Abcg1, and Apoe. Unexpectedly, the improved memory functions in the APPSLxPS1mut mice after T0901317 treatment were not accompanied by a decrease in Aβ plaque load in the cortex or hippocampus DG, CA1 or CA3. T0901317 administration also enhanced cerebral cholesterol turnover in aged C57BL/6NCrl mice, but did not further improve their memory functions.In conclusion, long-term activation of the LXR-pathway restored memory functions in aged APPSLxPS1mut mice with advanced Aβ deposition. However the beneficial effects of T0901317 on memory in the APPSLxPS1mut mice were independent of the Aβ plaque load in the hippocampus, but were associated with enhanced brain cholesterol turnover.     

β淀粉样蛋白及代谢酶类在阿尔茨海默病和糖尿病模型小鼠脑内的表达

目的观察阿尔茨海默病(AD)和糖尿病模型小鼠脑内β淀粉样蛋白(Aβ)及代谢相关酶类的表达情况,以便从分子水平找到糖尿病并发AD的实验室依据。方法 5月龄双转基因痴呆症模型小鼠(APP/PS1双转基因小鼠)、ob/ob T2DM肥胖模型小鼠和野生型C57BL/6J小鼠为对照,分别用免疫组化染色、ELISA和Western blot检测脑内老年斑(SP)、Aβ含量及Aβ代谢酶类的表达情况。结果 APP/PS1小鼠大脑皮质及海马均可见一定数量的SP;ob/ob小鼠大脑皮质内偶可见SP,而对照组未见SP。与对照小鼠相比,APP/PS1与ob/ob小鼠脑内Aβ40、Aβ42的含量明显升高(P0.05);但APP/PS1小鼠脑内Aβ水平显著高于ob/ob小鼠(P0.05)。APP在APP/PS1小鼠脑内的表达显著高于其他两组小鼠;在ob/ob小鼠脑内的表达要强于对照小鼠(P0.05)。Aβ生成的关键酶BACE1在APP/PS1与ob/ob小鼠脑内的表达显著高于对照小鼠(P0.05),但其在APP/PS1小鼠脑内的表达要强于ob/ob小鼠(P0.05)。Aβ降解的关键酶IDE在APP/PS1与ob/ob小鼠脑内的表达显著低于对照小鼠(P0.05),且在ob/ob小鼠脑内表达最低。结论 Aβ生成与降解的异常以及其异常聚集沉积不仅发生在早期AD脑内,同时也发生在T2DM脑内,提示Aβ过表达可能是促进2型糖尿病并发AD的重要原因之一。     

Age‐Dependent Effect of β‐Amyloid Toxicity on Basal Forebrain Cholinergic Neurons and Inflammation in the Rat Brain

Beta‐amyloid (Aβ) accumulation, neuroinflammation, basal forebrain cholinergic loss and hippocampal degeneration are well‐described pathologies associated with Alzheimer's disease (AD). However, the role that age plays in the susceptibility of the brain to these AD pathologies and the relationships between them is still not well understood. This study investigated the age‐related response to intracerebroventricular injection of Aβ_25–35 in 3‐, 6‐ and 9‐month‐old rats. Aβ toxicity resulted in an age‐related increase in cholinergic loss and microglial activation in the basal forebrain along with neuronal loss in the hippocampal CA3 subfield. Performance in the Morris water maze revealed impairments in long‐term reference memory in 6‐month‐old Aβ administered animals, which was not seen in 3‐month‐old animals. These results support a role of Aβ administration in inducing age‐dependent cholinergic loss and neuroinflammation, and additionally provide evidence for a more age‐appropriate model of adult‐onset Aβ toxicity demonstrating pathological changes that reflect the early stages of AD pathogenesis including neuroinflammation, cholinergic loss and beginning stages of memory impairment.     

The PKR activator PACT is induced by Aβ: involvement in Alzheimer's disease

The neuropathological hallmarks of Alzheimer's disease (AD) include senile plaques made of Aβ peptide, neurofibrillary tangles containing hyperphosphorylated tau protein and neuronal loss. The pro-apoptotic kinase PKR can be activated by Aβ and can phosphorylate tau protein via GSK3β kinase activation. The activated form of PKR (pPKR) accumulates in affected neurons and could participate in neuronal degeneration in AD. The mechanism of abnormal PKR activation in AD is not elucidated but could be linked to the PKR activator PACT. PACT stainings, and levels were assessed in the brains of AD patients and in APP/PS1 knock-in transgenic mice and in cell cultures exposed to stresses. We showed that PACT and pPKR colocalizations are enhanced in AD brains. Their levels are increased and correlated in AD and APP/PS1 knock-in mice brains. In human neuroblastoma cells exposed to Aβ, tunicamycin or H2O2, PACT and pPKR concentrations are increased. PACT then PKR inhibitions indicate that PACT is upstream of PKR activation. Our findings demonstrate that PACT levels are enhanced in AD brains and could partly be caused by the action of Aβ. In addition, PACT participates in PKR activation. The PACT-PKR pathway represents a potential link between Aβ accumulation, PKR activation and tau phosphorylation.     

Nicotinamide riboside restores cognition through an upregulation of proliferator-activated receptor-γ coactivator 1α regulated β-secretase 1 degradation and mitochondrial gene expression in Alzheimer's mouse models

Nicotinamide adenine dinucleotide (NAD)⁺, a coenzyme involved in redox activities in the mitochondrial electron transport chain, has been identified as a key regulator of the lifespan-extending effects, and the activation of NAD⁺ expression has been linked with a decrease in beta-amyloid (Aβ) toxicity in Alzheimer's disease (AD). Nicotinamide riboside (NR) is a NAD⁺ precursor, it promotes peroxisome proliferator-activated receptor-γ coactivator 1 (PGC)-1α expression in the brain. Evidence has shown that PGC-1α is a crucial regulator of Aβ generation because it affects β-secretase (BACE1) degradation. In this study we tested the hypothesis that NR treatment in an AD mouse model could attenuate Aβ toxicity through the activation of PGC-1α-mediated BACE1 degradation. Using the Tg2576 AD mouse model, using in vivo behavioral analyses, biochemistry assays, small hairpin RNA (shRNA) gene silencing and electrophysiological recording, we found (1) dietary treatment of Tg2576 mice with 250 mg/kg/day of NR for 3 months significantly attenuates cognitive deterioration in Tg2576 mice and coincides with an increase in the steady-state levels of NAD⁺ in the cerebral cortex; (2) application of NR to hippocampal slices (10 μM) for 4 hours abolishes the deficits in long-term potentiation recorded in the CA1 region of Tg2576 mice; (3) NR treatment promotes PGC-1α expression in the brain coinciding with enhanced degradation of BACE1 and the reduction of Aβ production in Tg2576 mice. Further in vitro studies confirmed that BACE1 protein content is decreased by NR treatment in primary neuronal cultures derived from Tg2576 embryos, in which BACE1 degradation was prevented by PGC-1α-shRNA gene silencing; and (4) NR treatment and PGC-1α overexpression enhance BACE1 ubiquitination and proteasomal degradation. Our studies suggest that dietary treatment with NR might benefit AD cognitive function and synaptic plasticity, in part by promoting PGC-1α-mediated BACE1 ubiquitination and degradation, thus preventing Aβ production in the brain.     

Selective benefits of simvastatin in bitransgenic APPSwe,Ind/TGF-β1 mice

Cognitive and cerebrovascular deficits are 2 landmarks of Alzheimer's disease (AD) to target for effective therapy. Here, we evaluated the efficacy of simvastatin in bitransgenic A/T mice overexpressing a mutated form of the human amyloid precursor protein (APP_Swe,Ind) and a constitutively active form of transforming growth factor-β1. These mice feature the AD amyloid beta (Aβ) and cerebrovascular pathology. Simvastatin significantly decreased insoluble Aβ peptide levels and Aβ plaque load despite no effect on β-site amyloid precursor protein-cleaving enzyme and Aβ-degrading enzyme neprilysin protein levels. However, simvastatin failed to improve spatial learning and memory deficits and the decreased baseline levels of the memory-related protein early growth response-1 (Egr-1) in the hippocampus CA1 area. The impaired hyperemic response to whisker stimulation in A/T mice was not improved with treatment, but simvastatin fully restored constitutive nitric oxide synthesis in vessel walls and exacerbated agonist-mediated dilatory deficits. These findings point to the efficacy of simvastatin on selective AD features in a complex model of the disease, likely reflecting the challenges faced by recent clinical trials in assessing statin efficacy.     

Knockout of plasminogen activator inhibitor 1 gene reduces amyloid beta peptide burden in a mouse model of Alzheimer's disease

Accumulation of amyloid beta peptide (Aβ) in the brain is a pathological hallmark of Alzheimer's disease (AD); the underlying mechanism, however, is not well understood. In this study, we show that expression of plasminogen activator inhibitor 1 (PAI-1), a physiological inhibitor of tissue type and urokinase type plasminogen activators (tPA and uPA), increases with age in the brain of wild type and Aβ precursor protein-presenilin 1 (APP/PS1) transgenic mice as well as in AD patients. Most importantly, we show that knocking out the PAI-1 gene dramatically reduces Aβ burden in the brain of APP/PS1 mice but has no effect on the levels of full-length APP, alpha or beta C-terminal fragments. Furthermore, we show that knocking out the PAI-1 gene leads to increases in the activities of tPA and plasmin, and the plasmin activity inversely correlates with the amounts of SDS insoluble Aβ40 and Aβ42. Together, these data suggest that increased PAI-1 expression/activity contributes importantly to Aβ accumulation during aging and in AD probably by inhibiting plasminogen activation and thus Aβ degradation.     

Cerebrovascular miRNAs correlate with the clearance of Aβ through perivascular route in younger 3xTg‐AD mice

The “two‐hit vascular hypothesis for Alzheimer's disease (AD)” and amyloid‐β (Aβ) oligomer hypothesis suggest that impaired soluble Aβ oligomers clearance through the cerebral vasculature may be an initial step of the AD process. Soluble Aβ oligomers are driven into perivascular spaces from the brain parenchyma and toward peripheral blood flow. The underlying vascular‐based mechanism, however, has not been defined. Given that microRNAs (miRNAs), emerging as novel modulators, are involved in numerous physiological and pathological processes, we hypothesized that cerebrovascular miRNAs may regulate the activities of brain blood vessels, which further affects the concentration of Aβ in the AD brain. In this study, perivascular Aβ deposits, higher vascular activation, increased pericyte coverage and up‐regulated capillaries miRNAs at 6 months old (6 mo) were found to correlate with the lower Aβ levels of middle AD stage (9 mo) in 3xTg‐AD (3xTg) mice. It is implicated that at the early stage of AD when intracellular Aβ appeared, higher expression of vessel‐specific miRNAs, elevated pericyte coverage, and activated endothelium facilitate Aβ oligomer clearance through the perivascular route, resulting in a transient reduction of Aβ oligomers at 9 mo. Additionally, ghrelin‐induced upregulation of capillary miRNAs and increased pericyte coverage attenuated Aβ burden at 9 mo, in further support of the relationship between vascular miRNAs and Aβ clearance. This work suggests a cerebral microvessel miRNA may boost endothelial highly activated phenotypes to promote elimination of Aβ oligomers through the perivascular drainage pathway and contribute to AD progression. The targeting of brain vessel‐specific miRNAs may provide a new rationale for the development of innovative therapeutic strategies for AD treatment.     

Alzheimer amyloid beta inhibition of Eg5/kinesin 5 reduces neurotrophin and/or transmitter receptor function

The mechanism by which amyloid beta (Aβ) causes neuronal dysfunction and/or death in Alzheimer's disease (AD) is unclear. Previously, we showed that Aβ inhibits several microtubule-dependent kinesin motors essential for mitosis and also present in mature neurons. Here, we show that inhibition of kinesin 5 (Eg5) by Aβ blocks neuronal function by reducing transport of neurotrophin and neurotransmitter receptors to the cell surface. Specifically, cell-surface NGF/NTR(p75) and NMDA receptors decline in cells treated with Aβ or the kinesin 5 inhibitor monastrol, or expressing APP. Aβ and monastrol also inhibit NGF-dependent neurite outgrowth from PC12 cells and glutamate-dependent Ca++ entry into primary neurons. Like Aβ, monastrol inhibits long-term potentiation, a cellular model of NMDA-dependent learning and memory, and kinesin 5 activity is absent from APP/PS transgenic mice brain or neurons treated with Aβ. These data imply that cognitive deficits in AD may derive in part from inhibition of neuronal Eg5 by Aβ, resulting in impaired neuronal function and/or survival through receptor mislocalization. Preventing inhibition of Eg5 or other motors by Aβ may represent a novel approach to AD therapy.     

Mechanisms underlying basal and learning-related intrinsic excitability in a mouse model of Alzheimer's disease

Accumulations of β-amyloid (Aβ) contribute to neurological deficits associated with Alzheimer's disease (AD). The effects of Aβ on basal neuronal excitability and learning-related AHP plasticity were examined using whole-cell recordings from hippocampal neurons in the 5XFAD mouse model of AD. A robust increase in Aβ42 (and elevated levels of Aβ38-40) in naïve 5XFAD mice was associated with decreased basal neuronal excitability, evidenced by a select increase in Ca²⁺-sensitive afterhyperpolarization (AHP). Moreover, trace fear deficits observed in a subset of 5XFAD weak-learner mice were associated with a greater enhancement of the AHP in neurons, as compared to age-matched 5XFAD learner and 5XFAD naïve mice. Importantly, learning-related plasticity of the AHP remained intact in a subset of 5XFAD mice that learned trace fear conditioning to a set criterion. We show that APP-PS1 mutations enhance Aβ and disrupt basal excitability via a Ca²⁺-dependent enhancement of the AHP, and suggest disruption to learning-related modulation of intrinsic excitability resulted, in part, from altered cholinergic modulation of the AHP in the 5XFAD mouse model of AD (170 of 170).     

Abnormal interaction between the mitochondrial fission protein Drp1 and hyperphosphorylated tau in Alzheimer's disease neurons: implications for mitochondrial dysfunction and neuronal damage

We recently reported increased mitochondrial fission and decreased fusion, increased amyloid beta (Aβ) interaction with the mitochondrial fission protein Drp1, increased mitochondrial fragmentation, impaired axonal transport of mitochondria and synaptic degeneration in neurons affected by AD. In the present study, we extended our previous investigations to determine whether phosphorylated tau interacts with Drp1 and to elucidate mitochondrial damage in the progression of AD. We also investigated GTPase activity, which is critical for mitochondrial fragmentation, in postmortem brain tissues from patients with AD and brain tissues from APP, APP/PS1 and 3XTg.AD mice. Using co-immunoprecipitation and immunofluorescence analyses, for the first time, we demonstrated the physical interaction between phosphorylated tau and Drp1. Mitochondrial fission-linked GTPase activity was significantly elevated in the postmortem frontal cortex tissues from AD patients and cortical tissues from APP, APP/PS1 and 3XTg.AD mice. On the basis of these findings, we conclude that Drp1 interacts with Aβ and phosphorylated tau, likely leading to excessive mitochondrial fragmentation, and mitochondrial and synaptic deficiencies, ultimately possibly leading to neuronal damage and cognitive decline. Treatment designed to reduce the expression of Drp1, Aβ and/or phosphorylated tau may decrease the interaction between Drp1 and phosphorylated tau and the interaction between Drp1 and Aβ, conferring protection to neurons from toxic insults of excessive Drp1, Aβ and/or phosphorylated tau.     

Disruption of the Sleep-Wake Cycle and Diurnal Fluctuation of β-Amyloid in Mice with Alzheimer's Disease Pathology

Aggregation of β-amyloid (Aβ) in the brain begins to occur years before the clinical onset of Alzheimer's disease (AD). Before Aβ aggregation, concentrations of extracellular soluble Aβ in the interstitial fluid (ISF) space of the brain, which are regulated by neuronal activity and the sleep-wake cycle, correlate with the amount of Aβ deposition in the brain seen later. The amount and quality of sleep decline with normal aging and to a greater extent in AD patients. How sleep quality as well as the diurnal fluctuation in Aβ change with age and Aβ aggregation is not well understood. We report a normal sleep-wake cycle and diurnal fluctuation in ISF Aβ in the brain of the APPswe/PS1δE9 mouse model of AD before Aβ plaque formation. After plaque formation, the sleep-wake cycle markedly deteriorated and diurnal fluctuation of ISF Aβ dissipated. As in mice, diurnal fluctuation of cerebrospinal fluid Aβ in young adult humans with presenilin mutations was also markedly attenuated after Aβ plaque formation. Virtual elimination of Aβ deposits in the mouse brain by active immunization with Aβ(42) normalized the sleep-wake cycle and the diurnal fluctuation of ISF Aβ. These data suggest that Aβ aggregation disrupts the sleep-wake cycle and diurnal fluctuation of Aβ. Sleep-wake behavior and diurnal fluctuation of Aβ in the central nervous system may be functional and biochemical indicators, respectively, of Aβ-associated pathology.     

Sorafenib inhibits nuclear factor kappa B,decreases inducible nitric oxide synthase and cyclooxygenase-2 expression,and restores working memory in APPswe mice

Alzheimer's disease (AD) is characterized by memory loss and the upregulation of pro-neuroinflammatory factors such as cRaf-1, cyclooxygenase-2 (Cox-2), and the nuclear factor kappa B (NF-κB), as well as a downregulation of protein kinase A (PKA) activity and the activation by phosphorylation of its downstream factor CREB. We investigated the effect of the anti-cancer cRaf-1 inhibitor, sorafenib tosylate (Nexavar), on the expression of these factors and on the cognitive performance of aged APPswe mice. We found that chronic treatment with sorafenib stimulated PKA and CREB phosphorylation and inhibited cRaf-1 and NF-κB in the brains of APPswe mice. NF-κB controls the expression of several genes related to AD pathology, including iNOS and Cox-²Concurrent with NF-κB inhibition, sorafenib treatment decreased the cerebral expression of Cox-2 and iNOS in APPswe mice. It has recently been observed that Cox-2 inhibition prevents cognitive impairment in a mouse model of AD and amyloid beta peptide (Aβ)–induced inhibition of long-term potentiation (LTP). Consistent with the idea that Cox-2 inhibition can improve cognitive abilities, we found that sorafenib restored working memory abilities in aged APPswe mice without reducing Aβ levels in the brain. These findings suggest that sorafenib reduced AD pathology by reducing neuroinflammation.     

Differential levels of apolipoprotein E and butyrylcholinesterase show strong association with pathological signs of Alzheimer's disease in the brain in vivo

Recently, we reported that 3 of the known risk factors of Alzheimer's disease (AD), i.e., advanced age, apolipoprotein E (ApoE) ε4, and female gender, are associated with differential levels of ApoE proteins and butyrylcholinesterase (BuChE) in the cerebrospinal fluid (CSF) of AD patients. The ApoE ε4 allele and certain BuChE polymorphisms synergistically affect the conversion rate of mild cognitive impairment (MCI) to AD. Here, we investigated interrelationships between ApoE and BuChE levels, and pathological markers of AD in vivo. CSF from patients with probable AD, assessed for cerebral glucose metabolism (CMRglc; n = 50) and Pittsburgh compound B (PIB) retention (β-amyloid [Aβ] load, n = 29) by positron emission tomography (PET), was used for measurement of BuChE, ApoE, Aβ, tau, phosphorylated tau (P-tau) and interleukin-1β (IL-1β) levels. Levels of ApoE and BuChE strongly correlated with CMRglc (fluorodeoxyglucose [FDG]-PET, r = 0.54, p < 0.0001, n = 50), cerebral Aβ load (PIB retention, r = 0.73, p < 0.0001, n = 29), and CSF P-tau (r = 0.73, p < 0.0001, n = 33). High ApoE protein was tied to low CMRglc and high PIB retention and P-tau. BuChE levels had opposite relationships. Other CSF covariates were levels of interleukin-1β and Aβ₄₂ peptide. The pattern of the patients' cognitive Z-scores strongly supported these observations. High ApoE protein was also linked to changes in 3 of the biodynamic properties of BuChE. In vitro analysis indicated that high ApoE protein levels were related to an increased pool of dormant BuChE molecules with an abnormally high intrinsic catalytic rate in CSF, which was “turned on” by excess Aβ peptides. The findings suggest that abnormally high levels of ApoE may play a causative role in the pathological events of AD, particularly those involving the early cholinergic deficit in the AD brain, through modulation of cholinesterases activities, hence disturbing the acetylcholine-dependent activity of neurons and nonexcitable cells such as glial cells.