Familial Alzheimer's Disease Patients Research Articles

Sildenafil as a Candidate Drug for Alzheimer's Disease: Real-World Patient Data Observation and Mechanistic Observations from Patient-Induced Pluripotent Stem Cell-Derived Neurons.

Alzheimer's disease (AD) is a chronic neurodegenerative disease needing effective therapeutics urgently. Sildenafil, one of the approved phosphodiesterase-5 inhibitors, has been implicated as having potential effect in AD. To investigate the potential therapeutic benefit of sildenafil on AD. We performed real-world patient data analysis using the MarketScan® Medicare Supplemental and the Clinformatics® databases. We conducted propensity score-stratified analyses after adjusting confounding factors (i.e., sex, age, race, and comorbidities). We used both familial and sporadic AD patient induced pluripotent stem cells (iPSC) derived neurons to evaluate the sildenafil's mechanism-of-action. We showed that sildenafil usage is associated with reduced likelihood of AD across four new drug compactor cohorts, including bumetanide, furosemide, spironolactone, and nifedipine. For instance, sildenafil usage is associated with a 54% reduced incidence of AD in MarketScan® (hazard ratio [HR] = 0.46, 95% CI 0.32- 0.66) and a 30% reduced prevalence of AD in Clinformatics® (HR = 0.70, 95% CI 0.49- 1.00) compared to spironolactone. We found that sildenafil treatment reduced tau hyperphosphorylation (pTau181 and pTau205) in a dose-dependent manner in both familial and sporadic AD patient iPSC-derived neurons. RNA-sequencing data analysis of sildenafil-treated AD patient iPSC-derived neurons reveals that sildenafil specifically target AD related genes and pathobiological pathways, mechanistically supporting the beneficial effect of sildenafil in AD. These real-world patient data validation and mechanistic observations from patient iPSC-derived neurons further suggested that sildenafil is a potential repurposable drug for AD. Yet, randomized clinical trials are warranted to validate the causal treatment effects of sildenafil in AD.

Genetic modifiers of cognitive decline in PSEN1 E280A Alzheimer's disease.

Rate of cognitive decline (RCD) in Alzheimer's disease (AD) determines the degree of impairment for patients and of burden for caretakers. We studied the association of RCD with genetic variants in AD. RCD was evaluated in 62 familial AD (FAD) and 53 sporadic AD (SAD) cases, and analyzed by whole-exome sequencing for association with common exonic functional variants. Findings were validated in post mortem brain tissue. One hundred seventy-two gene variants in FAD, and 227 gene variants in SAD associated with RCD. In FAD, performance decline of the immediate recall of the Rey-Osterrieth figure test associated with 122 genetic variants. Olfactory receptor OR51B6 showed the highest number of associated variants. Its expression was detected in temporal cortex neurons. Impaired olfactory function has been associated with cognitive impairment in AD. Genetic variants in these or other genes could help to identify risk of faster memory decline in FAD and SAD patients.

Mutual interaction of neurons and astrocytes derived from iPSCs with APP V717L mutation developed the astrocytic phenotypes of Alzheimer’s disease

BackgroundThe development of induced pluripotent stem cells (iPSCs) technology has enabled human cellular disease modeling for inaccessible cell types, such as neural cells in the brain. However, many of the iPSC-derived disease models established to date typically involve only a single cell type. These monoculture models are inadequate for accurately simulating the brain environment, where multiple cell types interact. The limited cell type diversity in monoculture models hinders the accurate recapitulation of disease phenotypes resulting from interactions between different cell types. Therefore, our goal was to create cell models that include multiple interacting cell types to better recapitulate disease phenotypes.MethodsTo establish a co-culture model of neurons and astrocytes, we individually induced neurons and astrocytes from the same iPSCs using our novel differentiation methods, and then co-cultured them. We evaluated the effects of co-culture on neurons and astrocytes using immunocytochemistry, immuno-electron microscopy, and Ca2+ imaging. We also developed a co-culture model using iPSCs from a patient with familial Alzheimer's disease (AD) patient (APPV717L mutation) to investigate whether this model would manifest disease phenotypes not seen in the monoculture models.ResultsThe co-culture of the neurons and astrocytes increased the branching of astrocyte processes, the number of GFAP-positive cells, neuronal activities, the number of synapses, and the density of presynaptic vesicles. In addition, immuno-electron microscopy confirmed the formation of a tripartite synaptic structure in the co-culture model, and inhibition of glutamate transporters increased neuronal activity. Compared to the co-culture model of the control iPSCs, the co-culture model of familial AD developed astrogliosis-like phenotype, which was not observed in the monoculture model of astrocytes.ConclusionsCo-culture of iPSC-derived neurons and astrocytes enhanced the morphological changes mimicking the in vivo condition of both cell types. The formation of the functional tripartite synaptic structures in the co-culture model suggested the mutual interaction between the cells. Furthermore, the co-culture model with the APPV717L mutation expressed in neurons exhibited an astrocytic phenotype reminiscent of AD brain pathology. These results suggest that our co-culture model is a valuable tool for disease modeling of neurodegenerative diseases.

Cerebrovascular Dysfunction in Alzheimer's Disease and Transgenic Rodent Models.

Alzheimer's Disease (AD) and Alzheimer's Disease-Related Dementia (ADRD) are the primary causes of dementia that has a devastating effect on the quality of life and is a tremendous economic burden on the healthcare system. The accumulation of extracellular beta-amyloid (Aβ) plaques and intracellular hyperphosphorylated tau-containing neurofibrillary tangles (NFTs) in the brain are the hallmarks of AD. They are also thought to be the underlying cause of inflammation, neurodegeneration, brain atrophy, and cognitive impairments that accompany AD. The discovery of APP, PS1, and PS2 mutations that increase Aβ production in families with early onset familial AD led to the development of numerous transgenic rodent models of AD. These models have provided new insight into the role of Aβ in AD; however, they do not fully replicate AD pathology in patients. Familial AD patients with mutations that elevate the production of Aβ represent only a small fraction of dementia patients. In contrast, those with late-onset sporadic AD constitute the majority of cases. This observation, along with the failure of previous clinical trials targeting Aβ or Tau and the modest success of recent trials using Aβ monoclonal antibodies, has led to a reappraisal of the view that Aβ accumulation is the sole factor in the pathogenesis of AD. More recent studies have established that cerebral vascular dysfunction is one of the earliest changes seen in AD, and 67% of the candidate genes linked to AD are expressed in the cerebral vasculature. Thus, there is an increasing appreciation of the vascular contribution to AD, and the National Institute on Aging (NIA) and the Alzheimer's Disease Foundation recently prioritized it as a focused research area. This review summarizes the strengths and limitations of the most commonly used transgenic AD animal models and current views about the contribution of Aβ accumulation versus cerebrovascular dysfunction in the pathogenesis of AD.

The Proteome Profile of Olfactory Ecto-Mesenchymal Stem Cells-Derived from Patients with Familial Alzheimer's Disease Reveals New Insights for AD Study.

Alzheimer's disease (AD), the most common neurodegenerative disease and the first cause of dementia worldwide, has no effective treatment, and its pathological mechanisms are not yet fully understood. We conducted this study to explore the proteomic differences associated with Familial Alzheimer's Disease (FAD) in olfactory ecto-mesenchymal stem cells (MSCs) derived from PSEN1 (A431E) mutation carriers compared with healthy donors paired by age and gender through two label-free liquid chromatography-mass spectrometry approaches. The first analysis compared carrier 1 (patient with symptoms, P1) and its control (healthy donor, C1), and the second compared carrier 2 (patient with pre-symptoms, P2) with its respective control cells (C2) to evaluate whether the protein alterations presented in the symptomatic carrier were also present in the pre-symptom stages. Finally, we analyzed the differentially expressed proteins (DEPs) for biological and functional enrichment. These proteins showed impaired expression in a stage-dependent manner and are involved in energy metabolism, vesicle transport, actin cytoskeleton, cell proliferation, and proteostasis pathways, in line with previous AD reports. Our study is the first to conduct a proteomic analysis of MSCs from the Jalisco FAD patients in two stages of the disease (symptomatic and presymptomatic), showing these cells as a new and excellent in vitro model for future AD studies.

Alterations of ATG4A and LC3B in neurons derived from Alzheimer's disease patients.

We investigated the alterations in autophagy-related molecules in neurons differentiated from induced pluripotent stem cells obtained from patients with Alzheimer's disease (AD). Consistent with our previous microarray data, ATG4A protein was upregulated in the neurons derived from a familial AD patient with an APP-E693Δ mutation who showed accumulation of intracellular amyloid β peptide (Aβ). This upregulation was reversed by inhibiting Aβ production, suggesting that the intracellular Aβ may be responsible for the upregulation of ATG4A. The LC3B-II/LC3B-I ratio, an index of autophagosome formation, was lower in the neurons derived from the AD patient with APP-E693Δ as well as the neurons derived from other familial and sporadic AD patients. These findings indicate that dysregulation of autophagy-related molecules may accelerate the pathogenesis of AD.

Presenilin Is Essential for ApoE Secretion, a Novel Role of Presenilin Involved in Alzheimer's Disease Pathogenesis.

Alzheimer's disease (AD) is a debilitating dementia characterized by progressive memory loss and aggregation of amyloid-β (Aβ) protein into amyloid plaques in patient brains. Mutations in presenilin (PS) lead to abnormal generation of Aβ, which is the major cause of familial AD (FAD), and apolipoprotein E4 (ApoE4) is the major genetic risk factor for sporadic AD (SAD) onset. However, whether dysfunction of PS is involved in the pathogenesis of SAD is largely unknown. We found that ApoE secretion was completely abolished in PS-deficient cells and markedly decreased by inhibition of γ-secretase activity. Blockade of γ-secretase activity by a γ-secretase inhibitor, DAPT, decreased ApoE secretion, suggesting an important role of γ-secretase activity in ApoE secretion. Reduced ApoE secretion is also observed in nicastrin-deficient cells with reduced γ-secretase activity. PS deficiency enhanced nuclear translocation of ApoE and binding of ApoE to importin α4, a nuclear transport receptor. Moreover, the expression of PS mutants in PS-deficient cells suppressed the restoration effects on ApoE secretion compared with the expression of wild-type PS. Plasma ApoE levels were lower in FAD patients carrying PS1 mutations compared with normal control subjects. Our findings suggest a novel role of PS contributing to the pathogenesis of SAD by regulating ApoE secretion.SIGNIFICANCE STATEMENT Familial AD (FAD) typically results from mutations in the genes encoding amyloid precursor protein, presenilin 1 (PS1), or PS2. Many PS mutants have been found to exert impaired γ-secretase activity and increased amyloid-β 42 (Aβ42)/Aβ40 ratio, which induce early amyloid deposition and FAD. On the other hand, apolipoprotein E4 (ApoE4) is the major genetic risk factor for sporadic AD (SAD) and contributes to AD pathogenesis because it has reduced Aβ clearance capability compared with ApoE3 and ApoE2. FAD and SAD have long been considered to be caused by these two independent mechanisms; however, for the first time, we demonstrated that PS is essential for ApoE secretion and PS mutants affected ApoE secretion in vitro and in human samples, suggesting a novel mechanism by which PS is also involved in SAD pathogenesis.

PS1 FAD mutant M146V decreases VEGF-induced angiogenesis in brain endothelial cells.

Alzheimer's disease (AD) is a multifactorial and progressive neurodegenerative disease, and the most common form of dementia. Cerebrovascular abnormalities and reduced vascular density are observed in human AD brains. Vascular pathology is an early event that contributes to the progression of AD and it can be caused by impaired angiogenesis. Brain angiogenesis in response to toxic insults is a reparative function regulated by endothelial cells (ECs); impairment in this function would render the brain vulnerable to insults. One of the most potent angiogenic factors, Vascular Endothelial Growth factor (VEGF), promotes angiogenesis by binding VEGFR2 receptor, a type I transmembrane protein (TMP). Most type I TMP are proteolytically processed by γ-secretase, which has presenilin 1 (PS1) as a catalytic subunit. Mutations in PS1 cause Familial AD (FAD) and reduce the activity of γ-secretase. We hypothesize that PS1 FAD mutants decrease the VEGF-induced processing of VEGFR2 and brain angiogenesis. Targeting brain angiogenesis could have therapeutic value in AD. Primary cortical endothelial cells (pCECs) were isolated and cultured from brains of wild type (WT) and PS1 M146V knockin mice, a "humanized" FAD model having the same genotype as in human FAD patients. We performed the in vitro angiogenesis assays sprouting on beads, migration and tube formation using pCEC cultures. Processing of VEGFR2 was studied in VEGFR2-overexpressed HEK293 cells in presence or absence of VEGF-A and γ-secretase inhibitor (RO4929097) with western blotting. We found that VEGFR2 is processed by γ-secretase and that VEGF-induced sprouting, tube formation, migration and angiogenic complexes between VE-cadherin and Rok-α kinase in pCEC are decreased in the presence of γ-secretase inhibitor. We also found that pCEC expressing PS1 FAD mutant M146V do not sprout in response to VEGF as efficiently as WT cells. Our findings suggest that VEGFR2 is processed by γ-secretase and that γ-secretase promotes VEGF-induced angiogenic functions of brain ECs. Our data also show that PS1 FAD mutant decreases angiogenic functions of pCEC. Importantly the effects of PS1 FAD mutants occur in the absence of amyloid plaques and neurofibrillary tangles indicating that PS1 FAD mutants can affect angiogenesis independent of the neuropathological hallmarks of AD.

The genetic risk effects of APOE ε4 and novel variants on Chinese familial and sporadic AD.

The genetic risk effects of apolipoprotein E (APOE) on familial Alzheimer's disease (FAD) with or without gene mutations, sporadic AD (SAD), and normal controls (NC) remain unclear in the Chinese population. Previous genome-wide association studies (GWAS) have identified dozens of susceptibility loci for sporadic Alzheimer's disease, but few of these loci have been validated in longitudinal cohorts. More than 15 thousand Chinese subjects, including FAD patients with or without pathogenic mutations (PSENs/APP), SAD patients, and normal controls (NC) were included from our large multi-center FAD and SAD cohorts. We analyzed the risk effects of APOE ε4 and performed a two-stage GWAS and built predictive models. The prevalence of the APOE ε4 genotype in FAD (unknown), FAD (PSENs/APP), SAD, and NC groups was 56.27%, 26.19%, 36.23%, and 19.54%, respectively. The APOE ε4 positive genotype had predictive power for FAD (unknown) risk (fig. 1, odds ratio: 4.51, 95% confidence interval: 3.57-5.45, P<.001). Four novel variants (rs3777215, rs6859823, rs234434, and rs2255835) as well as nine variants in the APOE region were identified with genome-wide significance. They are related to APP transport and metabolism, antioxidation, and neurogenesis. Using these variants, we built 11 predictive models that were all significant in predicting AD onset in both stages (fig. 2, peak of area under the curve reached 0.73). These models were validated using a separate longitudinal cohort, and results showed that individuals carrying risk variants included in the models had a shorter latency and higher incidence of AD. APOE ε4 positive genotype may cause familial aggregation, and the investigation of multiple interventions targeting APOE pathological function to reduce the risk for this disease warrants attention. This is the first study to validate GWAS-based predictive models for evaluating the risk of AD onset in a large Chinese population. The clinical application of these models will be beneficial for individuals harbouring these risk variants.

Amyloid-β40 E22K fibril in familial Alzheimer's disease is more thermostable and susceptible to seeding.

Alzheimer's disease (AD) is the most prevalent and devastating neurodegenerative disease occurred in the elderly. One of the pathogenic hallmarks is senile plaques composed of amyloid-β (Aβ) fibrils. Single mutations resided in Aβ were found in familial AD (FAD) patients that have early onset of the disease. The molecular details and properties of each FAD Aβ variants are still elusive. Here, we employed collective spectroscopic techniques to examine the properties of various Aβ40 fibrils. We generated fibrils of wild type (WT) and three FAD mutants on residue E22 including E22G, E22K, and E22Q. We monitored fibril formation by thioflavin T (ThT) assay, examined secondary structure by Fourier transform infrared and far-UV circular dichroism spectroscopy, imaged fibril morphology by transmission electron microscopy, and evaluated ThT-binding kinetics. In the thermal experiments, we found E22K fibrils resisted to high temperature and retained significant β-sheet content than the others. E22K fibril seeds after high-temperature treatment still possess the seeding property, whereas WT fibril seeds are disturbed after the treatment. Therefore, in this study we demonstrated the mutation at E22K increases the thermal stability and seeding function of amyloid fibrils.

Generation of gene edited hiPSC from familial Alzheimer's disease patient carrying N141I missense mutation in presenilin 2

Alzheimer's disease (AD) is the major cause of dementia worldwide. Early-onset familial AD accounts for about 0.5% of all AD and is caused by single major gene mutations and autosomal dominant inheritance. An N141I missense mutation is associated with a significant increase in basal cell death and apoptosis. In this work we generated hiPSC from skin fibroblasts obtained from an AD patient carrying a N141I missense mutation in PSEN2. The generated iPSC colonies grew and were characterized by pluripotency marker staining; the N141I missense mutation was corrected using genome editing technology.

Alzheimer's Disease in Individuals with Down Syndrome

Down syndrome (DS) is a genetic disorder that occurs due to trisomy on chromosome 21. It is known to relate to the amyloid-beta (A4) precursor protein (APP) gene and amyloid plaques, affecting developmental processes and resulting in early dementia, signifying a relation to Alzheimer's disease (AD). AD in individuals with DS affects many aspects include memory function, social and cognitive behavior. There is also a high likelihood for individuals with DS to have an AD at an early age, adding more challenges to the patients and the caregivers. Triplication of the gene in DS and an extra copy of APP in familial AD patients are responsible for the genetic link between these two diseases.

Generation of a human induced pluripotent stem cell line from a familial Alzheimer's disease PSEN1 T119I patient

Human induced pluripotent stem cells (hiPSC) line FLENIi001-A was reprogrammed from dermal fibroblasts using the lentiviral-hSTEMCCA-loxP vector. Fibroblasts were obtained from a skin biopsy of a 72-year-old Caucasian male familial Alzheimer's disease patient carrying the T119I mutation in the PSEN1 gene. PSEN1 genotype was maintained and stemness and pluripotency confirmed in the FLENIi001-A hiPSC line.

5-hydroxymethylcytosine is dynamically regulated during forebrain organoid development and aberrantly altered in Alzheimer's disease.

SUMMARY5-hydroxymethylcytosine (5hmC) undergoes dynamic changes during mammalian brain development, and its dysregulation is associated with Alzheimer’s disease (AD). The dynamics of 5hmC during early human brain development and how they contribute to AD pathologies remain largely unexplored. We generate 5hmC and transcriptome profiles encompassing several developmental time points of healthy forebrain organoids and organoids derived from several familial AD patients. Stage-specific differentially hydroxymethylated regions demonstrate an acquisition or depletion of 5hmC modifications across developmental stages. Additionally, genes concomitantly increasing or decreasing in 5hmC and gene expression are enriched in neurobiological or early developmental processes, respectively. Importantly, our AD organoids corroborate cellular and molecular phenotypes previously observed in human AD brains. 5hmC is significantly altered in developmentally programmed 5hmC intragenic regions in defined fetal histone marks and enhancers in AD organoids. These data suggest a highly coordinated molecular system that may be dysregulated in these early developing AD organoids.

Enhanced Neuronal Activity and Asynchronous Calcium Transients Revealed in a 3D Organoid Model of Alzheimer’s Disease

Advances in the development of three-dimensional (3D) brain organoids maintained in vitro have provided excellent opportunities to study brain development and neurodegenerative disorders, including Alzheimer's disease (AD). However, there remains a need to generate AD organoids bearing patient-specific genomic backgrounds that can functionally recapitulate the key features observed in the AD patient's brain. To address this need, we described a strategy to generate self-organizing 3D cerebral organoids which develop a functional neuronal network connectivity. This was achieved by neuroectoderm induction of human pluripotent stem cell (hPSCs) aggregates and subsequent differentiation into desired neuroepithelia and mature neurons in a 3D Matrigel matrix. Using this approach, we successfully generated AD cerebral organoids from human pluripotent stem cells (hPSCs) derived from a familial AD patient with a common mutation in presenilin 2 (PSEN2N141I). An isogenic control with an identical genetic background but wild-type PSEN2 was generated using CRISPR/Cas9 technology. Both control and AD organoids were characterized by analyzing their morphology, the Aβ42/Aβ40 ratio, functional neuronal network activity, drug sensitivity, and the extent of neural apoptosis. The spontaneous activity of the network and its synchronization was measured in the organoids via calcium imaging. We found that compared with the mutation-corrected control organoids, AD organoids had a higher Aβ42/Aβ40 ratio, asynchronous calcium transients, and enhanced neuronal hyperactivity, successfully recapitulating an AD-like pathology at the molecular, cellular, and network level in a human genetic context. Moreover, two drugs which increase neuronal activity, 4-aminopyridine (4-AP) and bicuculline methochloride, induced high-frequency synchronized network bursting to a similar extent in both organoids. Therefore, our study presents a promising organoid-based biosystem for the study of the pathophysiology of AD and a platform for AD drug development.

Optimization of in vitro gene delivery to neurons containing an APP gene with a mutation responsible for familial Alzheimer’s disease for the development of a base editing therapy

AbstractBackgroundThe Amyloïd Precursor Protein (APP) is preferentially cut by the α‐secretase enzyme in healthy individuals. However, an abnormal cleavage by β‐secretase leads to the accumulation of β‐amyloid peptides. Numerous APP genetic mutations cause Familial Alzheimer Disease (FAD). However, a rare APP gene variant (A673T) found in Icelanders drastically reduces cleavage by the β‐secretase. We hypothesized that the insertion of this A673T mutation in a patient’s genome using the CRISPR/Cas9 Base‐Editing Technology (Komor et al. Nature 2016) could be an effective method to slow down the progression of familial and sporadic forms of Alzheimer’s disease. The objective of this study is to eventually compare the efficiency by which a lentiviral or a dual‐AAV‐based vector could deliver a base‐editing complex (SpCas9VQR‐Target‐AID) into neurons in vitro.MethodNeurons were obtained using two methods. The first method involved differentiating fibroblasts from a FAD patient or a mouse model with a London (V717I) mutation into neurons (Shrigley et al. JoVE 2018) (Figure 1), while the second method involved isolating hippocampal neurons from prenatal NL/F/G mice (Seibenhener et al. JoVE 2012). The dual AAV complex was designed to deliver two parts of the base editor gene separated by inteins (Villiger et al. Nat Med 2018). Hippocampal or induced neurons were transduced with lentivirus or AAV1. Cas9 detection was performed by immunofluorescence and Western Blot. The β‐amyloid peptides in supernatant were characterized and quantified by Meso Scale Discovery’s Aβ kit.ResultWe have been able to detect the Cas9 protein in neurons by western blot and immunofluorescence (Figure 2). In subsequent experiments, we will determine which delivery method will reduce more the β‐amyloid peptide.ConclusionOur approach aims to confirm the protective effect of the A673T mutation against the development of familial and sporadic forms of Alzheimer’s disease as well as develop an efficient delivery method for the base editing complex which will lead to an in vivo application. Long‐term perspective: We aim to develop a completely new therapeutic approach for AD and FAD using base editing or the new PRIME editing technique (Anzalone et al. Nature 2019). This may eventually lead to a Phase I clinical trial.

Elucidating the role of SORL1 as an APOE receptor using iPSC‐derived astrocytes

AbstractBackgroundApolipoprotein E (APOE), the strongest genetic risk factor in late‐onset AD (LOAD), encodes a protein that can interact with Aβ and regulate its clearance. Interestingly, SORL1, another AD risk gene, belongs to the family of APOE receptors involved in Aβ clearance. SORL1 is the only APOE receptor gene that has been identified as a genetic risk factor in LOAD. Recent studies identified SORL1 loss‐of‐function variants in familial AD patients, suggesting that SORL1 may be a causal gene for AD. Here, we investigated the potential convergent mechanisms of APOE and SORL1 function in the brain by examining the novel function of SORL1 in human astrocytes in Aβ clearance.MethodiPSC‐derived astrocytes were generated from individuals with 1) different APOE isoforms 2) SORL1 knock out (KO), risk SNPs and missense mutations and 3) other AD risk SNPs using two astrocyte differentiation protocols. Aβ clearance assays were performed by treating the astrocytes with synthetic or cell derived Aβ, then monitoring the Aβ level in both media and lysate over time to determine the ability of astrocytes to uptake and clear Aβ.ResultWe have generated iPSC‐derived astrocytes from multiple lines to characterize whether SORL1 functions as an APOE receptor in human astrocytes. We determined that SORL1 is highly expressed in astrocytes, both in cytoplasmic and cell surface compartments, and SORL1 can interact with APOE in iPSCs as shown by co‐immunoprecipitation. Further, our preliminary data show that SORL1 KO astrocytes show elevated endogenous extracellular Aβ levels, and impaired Aβ clearance ability when treated with exogenous or cell derived Aβ. Lastly, when Aβ uptake was examined using APOE isogenic astrocytes, APOE KO show impaired clearance, supporting a role for endogenously secreted APOE in Aβ uptake in human astrocytes. Ongoing studies are interrogating the contribution of SORL1 in APOE‐mediated Aβ clearance.ConclusionHere, I have utilized iPSC‐derived astrocytes to examine the novel role of SORL1 as an APOE receptor in astrocytes, and investigate a potential convergent mechanism that APOE and SORL1 play in Aβ clearance.

A Comprehensive Analysis of Unique and Recurrent Copy Number Variations in Alzheimer’s Disease and its Related Disorders

Copy number variations (CNVs) play an important role in the genetic etiology of various neurological disorders, including Alzheimer's disease (AD). Type 2 diabetes mellitus (T2DM) and major depressive disorder (MDD) were shown to have share mechanisms and signaling pathways with AD. We aimed to assess CNVs regions that may harbor genes contributing to AD, T2DM, and MDD in 67 Saudi familial and sporadic AD patients, with no alterations in the known genes of AD and genotyped previously for APOE. DNA was analyzed using the CytoScan-HD array. Two layers of filtering criteria were applied. All the identified CNVs were checked in the Database of Genomic Variants (DGV). A total of 1086 CNVs (565 gains and 521 losses) were identified in our study. We found 73 CNVs harboring genes that may be associated with AD, T2DM or MDD. Nineteen CNVs were novel. Most importantly, 42 CNVs were unique in our studied cohort existing only in one patient. Two large gains on chromosomes 1 and 13 harbored genes implicated in the studied disorders. We identified CNVs in genes that encode proteins involved in the metabolism of amyloid-β peptide (AGRN, APBA2, CR1, CR2, IGF2R, KIAA0125, MBP, RER1, RTN4R, VDR and WISPI) or Tau proteins (CACNAIC, CELF2, DUSP22, HTRA1 and SLC2A14). The present work provided information on the presence of CNVs related to AD, T2DM, and MDD in Saudi Alzheimer's patients.

The APOE ε4 exerts differential effects on familial and other subtypes of Alzheimer's disease.

IntroductionThe genetic risk effects of apolipoprotein E (APOE) on familial Alzheimer's disease (FAD) with or without gene mutations, sporadic AD (SAD), and normal controls (NC) remain unclear in the Chinese population.MethodsIn total, 15 119 subjects, including 311 FAD patients without PSEN1, PSEN2, APP, TREM2, and SORL1 pathogenic mutations (FAD [unknown]); 126 FAD patients with PSENs/APP mutations (FAD [PSENs/APP]); 7234 SAD patients; and 7448 NC were enrolled. The risk effects of APOE ε4 were analyzed across groups.ResultsThe prevalence of the APOE ε4 genotype in FAD (unknown), FAD (PSENs/APP), SAD, and NC groups was 56.27%, 26.19%, 36.23%, and 19.54%, respectively. Further, the APOE ε4 positive genotype had predictive power for FAD (unknown) risk (odds ratio: 4.51, 95% confidence interval: 3.57–5.45, P < .001).Discussion APOE ε4 positive genotype may cause familial aggregation, and the investigation of multiple interventions targeting APOE pathological function to reduce the risk for this disease warrants attention.

Generation of human induced pluripotent stem cell line from Alzheimer's disease patient with PSEN2 N141I mutation using integration-free non-viral method.

Induced pluripotent stem cell (iPSC) line HUi001-A was reprogrammed from skin fibroblasts via non-integrating, virus free self-replicating RNA. Skin fibroblasts from an 81-year-old female Caucasian familial Alzheimer's disease patient of Volga German family carrying N141I mutation in the PSEN2 gene (familial AD4, clinical summary confirmed Alzheimer's disease) was obtained from the Coriell Institute (AG09908). Generated iPSCs were characterized and pluripotency was confirmed.