scholarly journals Abi3 regulates microglial ramification and dynamic tissue surveillance in vivo.

2021 ◽  
Author(s):  
Elena Simonazzi ◽  
Ruth Jones ◽  
Fangli Chen ◽  
Adam Ranson ◽  
Joshua Stevenson-Hoare ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Gene Family ◽  
Family Member ◽  
Late Onset ◽  
Gene Family Member ◽  
Surveillance Activity ◽  
Increased Risk ◽  
Microglial Morphology

A rare coding variant of Abelson-interactor gene family member 3 (Abi3) is associated with increased risk of late-onset Alzheimer's Disease (AD). Although Abi3 is recognised as a core microglial gene, its role in microglia is largely unknown. Here we demonstrate that Abi3 is crucial for normal microglial morphology, distribution, and homeostatic tissue surveillance activity in vivo.

scholarly journals Could Altered Evoked Pain Responsiveness Be a Phenotypic Biomarker for Alzheimer’s Disease Risk? A Cross-Sectional Analysis of Cognitively Healthy Individuals

2020 ◽  
pp. 1-7
Author(s):  
Raymond R. Romano ◽  
Michael A. Carter ◽  
Mary S. Dietrich ◽  
Ronald L. Cowan ◽  
Stephen P. Bruehl ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Healthy Subjects ◽  
Pain Sensitivity ◽  
Late Onset ◽  
Thermal Pain ◽  
Apoe4 Allele ◽  
Increased Risk ◽  
Pain Stimuli ◽  
Experimentally Induced

Background: This study evaluated whether the apolipoprotein ɛ4 (APOE4) allele, a genetic marker associated with increased risk of developing late-onset Alzheimer’s disease (AD), was associated with differences in evoked pain responsiveness in cognitively healthy subjects. Objective: The aim was to determine whether individuals at increased risk of late-onset AD based on APOE allele genotype differ phenotypically in their response to experimentally-induced painful stimuli compared to those who do not have at least one copy of the ɛ4 allele. Methods: Forty-nine cognitively healthy subjects aged 30–89 years old with the APOE4 allele (n = 12) and without (n = 37) were assessed for group differences in pain thresholds and affective (unpleasantness) responses to experimentally-induced thermal pain stimuli. Results: Statistically significant main effects of APOE4 status were observed for both the temperature at which three different pain intensity percepts were reached (p = 0.040) and the level of unpleasantness associated with each (p = 0.014). APOE4 positive participants displayed lower overall pain sensitivity than those who were APOE4 negative and also greater overall levels of pain unpleasantness regardless of intensity level. Conclusion: Cognitively healthy APOE4 carriers at increased risk of late-onset AD demonstrated reduced thermal pain sensitivity but greater unpleasantness to thermal pain stimuli relative to individuals at lower risk of late-onset AD. These results suggest that altered evoked pain perception could potentially be used as a phenotypic biomarker of late-onset AD risk prior to disease onset. Additional studies of this issue may be warranted.

scholarly journals Gga3 deletion and a GGA3 rare variant associated with late onset Alzheimer’s disease trigger BACE1 accumulation in axonal swellings

2020 ◽  
Vol 12 (570) ◽  
pp. eaba1871
Author(s):  
Selene Lomoio ◽  
Rachel Willen ◽  
WonHee Kim ◽  
Kevin Z. Ho ◽  
Edward K. Robinson ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Rare Variant ◽  
Late Onset ◽  
Early Stage ◽  
Loss Of Function ◽  
Axonal Trafficking ◽  
Axonal Swellings

Axonal dystrophy, indicative of perturbed axonal transport, occurs early during Alzheimer’s disease (AD) pathogenesis. Little is known about the mechanisms underlying this initial sign of the pathology. This study proves that Golgi-localized γ-ear-containing ARF binding protein 3 (GGA3) loss of function, due to Gga3 genetic deletion or a GGA3 rare variant that cosegregates with late-onset AD, disrupts the axonal trafficking of the β-site APP-cleaving enzyme 1 (BACE1) resulting in its accumulation in axonal swellings in cultured neurons and in vivo. We show that BACE pharmacological inhibition ameliorates BACE1 axonal trafficking and diminishes axonal dystrophies in Gga3 null neurons in vitro and in vivo. These data indicate that axonal accumulation of BACE1 engendered by GGA3 loss of function results in local toxicity leading to axonopathy. Gga3 deletion exacerbates axonal dystrophies in a mouse model of AD before β-amyloid (Aβ) deposition. Our study strongly supports a role for GGA3 in AD pathogenesis, where GGA3 loss of function triggers BACE1 axonal accumulation independently of extracellular Aβ, and initiates a cascade of events leading to the axonal damage distinctive of the early stage of AD.

scholarly journals Type 2 Diabetes Mellitus Increases The Risk of Late-Onset Alzheimer’s Disease: Ultrastructural Remodeling of the Neurovascular Unit and Diabetic Gliopathy

2019 ◽  
Vol 9 (10) ◽  
pp. 262 ◽  
Author(s):  
Hayden
Keyword(s):  
Diabetes Mellitus ◽  
Alzheimer’S Disease ◽  
Type 2 Diabetes ◽  
Alzheimer's Disease ◽  
Type 2 Diabetes Mellitus ◽  
Late Onset ◽  
Neurovascular Unit ◽  
Age Related ◽  
Increased Risk

Type 2 diabetes mellitus (T2DM) and late-onset Alzheimer’s disease–dementia (LOAD) are increasing in global prevalence and current predictions indicate they will only increase over the coming decades. These increases may be a result of the concurrent increases of obesity and aging. T2DM is associated with cognitive impairments and metabolic factors, which increase the cellular vulnerability to develop an increased risk of age-related LOAD. This review addresses possible mechanisms due to obesity, aging, multiple intersections between T2DM and LOAD and mechanisms for the continuum of progression. Multiple ultrastructural images in female diabetic db/db models are utilized to demonstrate marked cellular remodeling changes of mural and glia cells and provide for the discussion of functional changes in T2DM. Throughout this review multiple endeavors to demonstrate how T2DM increases the vulnerability of the brain’s neurovascular unit (NVU), neuroglia and neurons are presented. Five major intersecting links are considered: i. Aging (chronic age-related diseases); ii. metabolic (hyperglycemia advanced glycation end products and its receptor (AGE/RAGE) interactions and hyperinsulinemia-insulin resistance (a linking linchpin); iii. oxidative stress (reactive oxygen–nitrogen species); iv. inflammation (peripheral macrophage and central brain microglia); v. vascular (macrovascular accelerated atherosclerosis—vascular stiffening and microvascular NVU/neuroglial remodeling) with resulting impaired cerebral blood flow.

[P3-338]: IN VIVO TAU PET IMAGING IN EARLY-ONSET ALZHEIMER's DISEASE AND LATE-ONSET ALZHEIMER's DISEASE

2017 ◽  
Vol 13 (7S_Part_22) ◽  
pp. P1083-P1083
Author(s):  
Young Noh ◽  
Han Kyu Na ◽  
Seongho Seo ◽  
Sang-Yoon Lee ◽  
Hye Jin Jeong ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Pet Imaging ◽  
Early Onset ◽  
Late Onset ◽  
Early Onset Alzheimer’S Disease ◽  
Tau Pet ◽  
Tau Pet Imaging

scholarly journals Recent Consanguinity and Outbred Autozygosity Are Associated With Increased Risk of Late-Onset Alzheimer’s Disease

2021 ◽  
Vol 11 ◽  
Author(s):  
Valerio Napolioni ◽  
Marzia A. Scelsi ◽  
Raiyan R. Khan ◽  
Andre Altmann ◽  
Michael D. Greicius
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Ethnic Groups ◽  
Late Onset ◽  
Population Increase ◽  
Outbred Population ◽  
Genotype Relative Risk ◽  
Subsequent Work ◽  
Sequencing Project ◽  
Increased Risk

Prior work in late-onset Alzheimer’s disease (LOAD) has resulted in discrepant findings as to whether recent consanguinity and outbred autozygosity are associated with LOAD risk. In the current study, we tested the association between consanguinity and outbred autozygosity with LOAD in the largest such analysis to date, in which 20 LOAD GWAS datasets were retrieved through public databases. Our analyses were restricted to eight distinct ethnic groups: African–Caribbean, Ashkenazi–Jewish European, European–Caribbean, French–Canadian, Finnish European, North-Western European, South-Eastern European, and Yoruba African for a total of 21,492 unrelated subjects (11,196 LOAD and 10,296 controls). Recent consanguinity determination was performed using FSuite v1.0.3, according to subjects’ ancestral background. The level of autozygosity in the outbred population was assessed by calculating inbreeding estimates based on the proportion (FROH) and the number (NROH) of runs of homozygosity (ROHs). We analyzed all eight ethnic groups using a fixed-effect meta-analysis, which showed a significant association of recent consanguinity with LOAD (N = 21,481; OR = 1.262, P = 3.6 × 10–4), independently of APOE∗4 (N = 21,468, OR = 1.237, P = 0.002), and years of education (N = 9,257; OR = 1.274, P = 0.020). Autozygosity in the outbred population was also associated with an increased risk of LOAD, both for FROH (N = 20,237; OR = 1.204, P = 0.030) and NROH metrics (N = 20,237; OR = 1.019, P = 0.006), independently of APOE∗4 [(FROH, N = 20,225; OR = 1.222, P = 0.029) (NROH, N = 20,225; OR = 1.019, P = 0.007)]. By leveraging the Alzheimer’s Disease Sequencing Project (ADSP) whole-exome sequencing (WES) data, we determined that LOAD subjects do not show an enrichment of rare, risk-enhancing minor homozygote variants compared to the control population. A two-stage recessive GWAS using ADSP data from 201 consanguineous subjects in the discovery phase followed by validation in 10,469 subjects led to the identification of RPH3AL p.A303V (rs117190076) as a rare minor homozygote variant increasing the risk of LOAD [discovery: Genotype Relative Risk (GRR) = 46, P = 2.16 × 10–6; validation: GRR = 1.9, P = 8.0 × 10–4]. These results confirm that recent consanguinity and autozygosity in the outbred population increase risk for LOAD. Subsequent work, with increased samples sizes of consanguineous subjects, should accelerate the discovery of non-additive genetic effects in LOAD.

scholarly journals Trem2 Y38C Mutation and Loss of Trem2 Impairs Neuronal Synapses in Adult Mice

2020 ◽  
Author(s):  
Vaishnavi S. Jadhav ◽  
Peter BC. Lin ◽  
Guixiang Xu ◽  
Taylor Pennington ◽  
Gonzalo Viana Di Prisco ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Synaptic Plasticity ◽  
Late Onset ◽  
Synaptic Proteins ◽  
Synaptic Protein ◽  
Presenile Dementia ◽  
Altered Expression ◽  
Protein Levels

Abstract Background:Triggering receptor expressed on myeloid cells 2 (TREM2) is expressed in the brain exclusively on microglia and genetic variants are linked to neurodegenerative diseases including Alzheimer’s disease (AD), frontotemporal dementia (FTD) and NasuHakola Disease (NHD). The Trem2 variantR47H, confers substantially elevated risk of developing late onset Alzheimer’s disease, while NHD-linkedTrem2 variants like Y38Care associated with development of early onset dementia with white matter pathology. However, it is not known how these Trem2species predispose individuals to presenile dementia.Methods:To investigate if Trem2 Y38C or loss of Trem2 alters neuronal function, we generated a novel mouse model to introduce the NHD Trem2 Y38C variant in murine Trem2 using CRISPR/Cas9 technology. Trem2Y38/Y38C and Trem2-/-mice were assessed for Trem2 expression, differentially expressed genes, synaptic protein levels and synaptic plasticity using biochemical, electrophysiological and transcriptomic approaches.Results:While mice harboring Trem2 Y38C exhibited normal expression levels of Trem2, the pathological outcomes phenocopied Trem2-/- miceat 6 months. Transcriptomic analysis revealed altered expression of neuronal and oligodendrocytes/myelin genes. We observed regional decreases in synaptic protein levels, with the most affected synapses in the hippocampus. These alterations were associated with reduced synaptic plasticity. Conclusion:Our findings provide in vivo evidence that Trem2 Y38C disrupts normal TREM2 functions. Trem2Y38C/Y38Cand Trem2-/- mice demonstrated altered gene expression, changes in microglia morphology, loss of synaptic proteins and reduced hippocampal synaptic plasticity at 6 months in absence of any pathological triggers like tau or amyloid. This suggests TREM2 impacts neuronal functions and providesmolecular insights on the predisposition of individuals with TREM2 variants resulting in presenile dementia.

The Association between TREM2 Gene and Late-Onset Alzheimer’s Disease in Chinese Han Population

Gerontology ◽  
2021 ◽  
pp. 1-7
Author(s):  
Yan Sun ◽  
Yun-Ke Zhang ◽  
Hai Chen ◽  
Ren-Shou Chen
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Logistic Regression ◽  
Regression Analysis ◽  
Environmental Factors ◽  
Logistic Regression Analysis ◽  
Late Onset ◽  
Increased Risk ◽  
The Impact ◽  
Load Risk

Objective: : The objective of this study was to evaluate the impact of single nucleotide polymorphisms (SNPs) in triggering receptor expressed on the myeloid cells 2 protein (TREM2) gene and their interaction with environmental factors and haplotypes on late-onset Alzheimer’s disease (LOAD). Methods: DNA was extracted from the whole blood of the participants and genotyped using PCR and followed by restriction fragment length polymorphism. The Hardy-Weinberg equilibrium test was used in the control group. Multivariate logistic regression analysis was used to determine the relationship between the 4 SNPs of the TREM2 gene and the risk of LOAD. Generalized multifactor dimensionality reduction was used to test the best interaction combination between SNPs and environmental factors. Results: Logistic regression analysis showed that the T allele of rs75932628 and the T allele of rs2234253 were independently associated with increased risk of LOAD, and adjusted odds ratios (ORs) were 1.81 (1.271–2.35) and 1.59 (1.15–2.03), respectively. However, there was no significant association with LOAD for rs142232675 and rs143332484. We found a best model significantly associated with LOAD risk that consisted of rs75932628 and smoking, which scored 10/10 for both the sign test and cross-validation consistency (p = 0.012). Stratified analysis indicated that current smokers with rs75932628-CT/TT genotype have the highest LOAD risk compared to never smokers with rs75932628 – CC genotype, OR (95% confidence interval) = 2.73 (1.72–3.79). Haplotypes of rs75932628 and rs2234253 were analyzed using the SHEsis online software. However, no haplotype was found to be significantly associated with the risk of LOAD. Conclusions: The T allele of rs75932628 and the T allele of rs2234253 and interaction between rs75932628 and smoking were all correlated with increased risk of LOAD.

scholarly journals The influence of the R47H TREM2 variant on microglial exosome profiles

2021 ◽  
Author(s):  
Anna Mallach ◽  
Johan Gobom ◽  
Henrik Zetterberg ◽  
John Hardy ◽  
Thomas M Piers ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Late Onset ◽  
Negative Regulation ◽  
Common Variant ◽  
Regulation Of Transcription ◽  
Phagocytic Cell ◽  
Increased Risk ◽  
Human Ipsc ◽  
Subsequent Addition

Abstract Variants in the triggering receptor expressed on myeloid cells 2 (TREM2) gene are linked with an increased risk of dementia, in particular the R47Hhet  TREM2 variant is linked to late-onset Alzheimer’s disease. Using human iPSC-derived microglia, we assessed whether variations in the dynamics of exosome secretion, including their components, from these cells might underlie some of this risk. We found exosome size was not altered between common variant controls and R47Hhet variants, but the amount and constitution of exosomes secreted were different. Exosome quantities were rescued by incubation with an ATP donor or with lipids via a phosphatidylserine TREM2 ligand. Following a lipopolysaccharide or phagocytic cell stimulus, exosomes from common variant and R47Hhet microglia were found to contain cytokines, chemokines, APOE and TREM2. Differences were observed in the expression of CCL22, IL-1β and TREM2 between common variant and R47Hhet derived exosomes. Furthermore unlike common variant-derived exosomes, R47Hhet exosomes contained additional proteins linked to negative regulation of transcription and metabolic processes. Subsequent addition of exosomes to stressed neurones showed R47Hhet-derived exosomes to be less protective. These data have ramifications for the responses of microglia in Alzheimer’s disease and may point to further targets for therapeutic intervention.

Neuroticism Is Associated with Tau Pathology in Cognitively Unimpaired Individuals with Autosomal Dominant Alzheimer’s Disease

2021 ◽  
pp. 1-14
Author(s):  
Ana Baena ◽  
Yamile Bocanegra ◽  
Valeria Torres ◽  
Clara Vila-Castelar ◽  
Edmarie Guzmán-Vélez ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Personality Traits ◽  
Autosomal Dominant ◽  
Amyloid Pet ◽  
Tau Pathology ◽  
Mutation Carriers ◽  
Imaging Results ◽  
Increased Risk

Background: Greater neuroticism has been associated with higher risk for Alzheimer’s disease (AD) dementia. However, the directionality of this association is unclear. We examined whether personality traits differ between cognitively-unimpaired carriers of autosomal-dominant AD (ADAD) and non-carriers, and are associated with in vivo AD pathology. Objective: To determine whether personality traits differ between cognitively unimpaired ADAD mutation carriers and non-carriers, and whether the traits are related to age and AD biomarkers. Methods: A total of 33 cognitively-unimpaired Presenilin-1 E280A mutation carriers and 41 non-carriers (ages 27–46) completed neuropsychological testing and the NEO Five-Factor Personality Inventory. A subsample (n = 46; 20 carriers) also underwent tau and amyloid PET imaging. Results: Carriers reported higher neuroticism relative to non-carriers, although this difference was not significant after controlling for sex. Neuroticism was positively correlated with entorhinal tau levels only in carriers, but not with amyloid levels. Conclusion: The finding of higher neuroticism in carriers and the association of this trait with tau pathology in preclinical stages of AD highlights the importance of including personality measures in the evaluation of individuals at increased risk for cognitive impairment and dementia. Further research is needed to characterize the mechanisms of these relationships.

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