scholarly journals Characterization of Brain Iron Deposition Pattern and Its Association With Genetic Risk Factor in Alzheimer’s Disease Using Susceptibility-Weighted Imaging

2021 ◽  
Vol 15 ◽  
Author(s):  
Peiting You ◽  
Xiang Li ◽  
Zhijiang Wang ◽  
Huali Wang ◽  
Bin Dong ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Association Studies ◽  
Iron Deposition ◽  
Susceptibility Weighted Imaging ◽  
Normal Brain ◽  
Brain Iron ◽  
Brain Functions ◽  
The Brain ◽  
Brain Iron Deposition

The presence of iron is an important factor for normal brain functions, whereas excessive deposition of iron may impair normal cognitive function in the brain and lead to Alzheimer’s disease (AD). MRI has been widely applied to characterize brain structural and functional changes caused by AD. However, the effectiveness of using susceptibility-weighted imaging (SWI) for the analysis of brain iron deposition is still unclear, especially within the context of early AD diagnosis. Thus, in this study, we aim to explore the relationship between brain iron deposition measured by SWI with the progression of AD using various feature selection and classification methods. The proposed model was evaluated on a 69-subject SWI imaging dataset consisting of 24 AD patients, 21 mild cognitive impairment patients, and 24 normal controls. The identified AD progression-related regions were then compared with the regions reported from previous genetic association studies, and we observed considerable overlap between these two. Further, we have identified a new potential AD-related gene (MEF2C) closely related to the interaction between iron deposition and AD progression in the brain.

scholarly journals Glycogen Synthase Kinase-3β: A Mediator of Inflammation in Alzheimer's Disease?

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Jari Koistinaho ◽  
Tarja Malm ◽  
Gundars Goldsteins
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Glycogen Synthase ◽  
Immune Defense ◽  
Glycogen Synthase Kinase ◽  
Glycogen Synthase Kinase 3 ◽  
Normal Brain ◽  
Brain Functions ◽  
The Brain

Proliferation and activation of microglial cells is a neuropathological characteristic of brain injury and neurodegeneration, including Alzheimer's disease. Microglia act as the first and main form of immune defense in the nervous system. While the primary function of microglia is to survey and maintain the cellular environment optimal for neurons in the brain parenchyma by actively scavenging the brain for damaged brain cells and foreign proteins or particles, sustained activation of microglia may result in high production of proinflammatory mediators that disturb normal brain functions and even cause neuronal injury. Glycogen synthase kinase-3βhas been recently identified as a major regulator of immune system and mediates inflammatory responses in microglia. Glycogen synthase kinase-3βhas been extensively investigated in connection to tau and amyloidβtoxicity, whereas reports on the role of this enzyme in neuroinflammation in Alzheimer's disease are negligible. Here we review and discuss the role of glycogen synthase-3βin immune cells in the context of Alzheimer's disease pathology.

scholarly journals ApoE4 attenuates cortical neuronal activity and impairs memory in young apoE4 rats

2021 ◽  
Author(s):  
Ilona Har-Paz ◽  
Elor Arieli ◽  
Anan Moran
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Risk Factor ◽  
Neuronal Activity ◽  
Genetic Risk ◽  
Cortical Neurons ◽  
Late Onset ◽  
Genetic Risk Factor ◽  
Normal Brain ◽  
Brain Functions

AbstractThe E4 allele of apolipoprotein E (apoE4) is the strongest genetic risk factor for late-onset Alzheimer’s disease (AD). However, apoE4 may cause innate brain abnormalities before the appearance of AD related neuropathology. Understanding these primary dysfunctions is vital for early detection of AD and the development of therapeutic strategies for it. Recently we have shown impaired extra-hippocampal memory in young apoE4 mice – a deficit that was correlated with attenuated structural pre-synaptic plasticity in cortical and subcortical regions. Here we test the hypothesis that these early structural deficits impact learning via changes in basal and stimuli evoked neuronal activity. We recorded extracellular neuronal activity from the gustatory cortex (GC) of three-month-old humanized apoE4 and wildtype rats, before and after conditioned taste aversion (CTA) training. Despite normal sucrose drinking behavior before CTA, young apoE4 rats showed impaired CTA learning, consistent with our previous results in apoE4 mice. This behavioral deficit was correlated with decreased basal and taste-evoked firing rates in both putative excitatory and inhibitory GC neurons. Single neuron and ensemble analyses of taste coding demonstrated that apoE4 neurons could be used to correctly classify tastes, but were unable to undergo plasticity to support learning. Our results suggest that apoE4 impacts brain excitability and plasticity early in life and may act as an initiator for later AD pathologies.Significant statementThe ApoE4 allele is the strongest genetic risk-factor for late-onset Alzheimer’s disease (AD), yet the link between apoE4 and AD is still unclear. Recent molecular and in-vitro studies suggest that apoE4 interferes with normal brain functions decades before the development of its related AD neuropathology. Here we recorded the activity of cortical neurons from young apoE4 rats during extra-hippocampal learning to study early apoE4 neuronal activity abnormalities, and their effects over coding capacities. We show that apoE4 drastically reduces basal and stimuli-evoked cortical activity in both excitatory and inhibitory neurons. The apoE4-induced activity attenuation did not prevent coding of stimuli identity and valence, but impaired capacity to undergo activity changes to support learning. Our findings support the hypothesis that apoE4 interfere with normal neuronal plasticity early in life; a deficit that may lead to late-onset AD development.

scholarly journals Cellular Senescence and Iron Dyshomeostasis in Alzheimer’s Disease

2019 ◽  
Vol 12 (2) ◽  
pp. 93 ◽  
Author(s):  
Shashank Masaldan ◽  
Abdel Ali Belaidi ◽  
Scott Ayton ◽  
Ashley I. Bush
Keyword(s):  
Oxidative Stress ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Hydroxyl Radicals ◽  
Iron Accumulation ◽  
Brain Iron ◽  
Dependent Cell ◽  
Cellular Dysfunction ◽  
The Impact ◽  
The Brain

Iron dyshomeostasis is a feature of Alzheimer’s disease (AD). The impact of iron on AD is attributed to its interactions with the central proteins of AD pathology (amyloid precursor protein and tau) and/or through the iron-mediated generation of prooxidant molecules (e.g., hydroxyl radicals). However, the source of iron accumulation in pathologically relevant regions of the brain and its contribution to AD remains unclear. One likely contributor to iron accumulation is the age-associated increase in tissue-resident senescent cells that drive inflammation and contribute to various pathologies associated with advanced age. Iron accumulation predisposes ageing tissue to oxidative stress that can lead to cellular dysfunction and to iron-dependent cell death modalities (e.g., ferroptosis). Further, elevated brain iron is associated with the progression of AD and cognitive decline. Elevated brain iron presents a feature of AD that may be modified pharmacologically to mitigate the effects of age/senescence-associated iron dyshomeostasis and improve disease outcome.

Understanding the function of ABCA7 in Alzheimer's disease

2015 ◽  
Vol 43 (5) ◽  
pp. 920-923 ◽  
Author(s):  
Hongyun Li ◽  
Tim Karl ◽  
Brett Garner
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Association Studies ◽  
Chinese Hamster Ovary Cells ◽  
Amyloid Β ◽  
Mutant Form ◽  
Genome Wide Association Studies ◽  
App Processing ◽  
The Brain

ATP-binding cassette transporter A7 (ABCA7) is highly expressed in the brain. Recent genome-wide association studies (GWAS) identify ABCA7 single nt polymorphisms (SNPs) that increase Alzheimer's disease (AD) risk. It is now important to understand the true function of ABCA7 in the AD context. We have begun to address this using in vitro and in vivo AD models. Our initial studies showed that transient overexpression of ABCA7 in Chinese hamster ovary cells stably expressing human amyloid precursor protein (APP) resulted in an approximate 50% inhibition in the production of the AD-related amyloid-β (Aβ) peptide as compared with mock-transfected cells. This increased ABCA7 expression was also associated with alterations in other markers of APP processing and an accumulation of cellular APP. To probe for a function of ABCA7 in vivo, we crossed Abca7−/− mice with J20 mice, an amyloidogenic transgenic AD mouse model [B6.Cg-Tg(PDGFB-APPSwInd)20Lms/J] expressing a mutant form of human APP bearing both the Swedish (K670N/M671L) and Indiana (V717F) familial AD mutations. We found that ABCA7 loss doubled insoluble Aβ levels and amyloid plaques in the brain. This did not appear to be related to changes in APP processing (C-terminal fragment analysis), which led us to assess other mechanism by which ABCA7 may modulate Aβ homoeostasis. As we have shown that microglia express high levels of ABCA7, we examined a role for ABCA7 in the phagocytic clearance of Aβ. Our data indicated that the capacity for bone marrow-derived macrophages derived from Abca7−/− mice to phagocytose Aβ was reduced by 51% compared with wild-type (WT) mice. This suggests ABCA7 plays a role in the regulation of Aβ homoeostasis in the brain and that this may be related to Aβ clearance by microglia.

scholarly journals ABCA7 and Pathogenic Pathways of Alzheimer’s Disease

2018 ◽  
Vol 8 (2) ◽  
pp. 27 ◽  
Author(s):  
◽  
◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Association Studies ◽  
Amyloid Β ◽  
Current Evidence ◽  
Genome Wide Association Studies ◽  
In Vivo Models ◽  
Peripheral Tissues ◽  
Increased Risk ◽  
The Brain

The ATP-binding cassette (ABC) reporter family functions to regulate the homeostasis of phospholipids and cholesterol in the central nervous system, as well as peripheral tissues. ABCA7 belongs to the A subfamily of ABC transporters, which shares 54% sequence identity with ABCA1. While ABCA7 is expressed in a variety of tissues/organs, including the brain, recent genome-wide association studies (GWAS) have identified ABCA7 gene variants as susceptibility loci for late-onset Alzheimer’s disease (AD). More important, subsequent genome sequencing analyses have revealed that premature termination codon mutations in ABCA7 are associated with the increased risk for AD. Alzheimer’s disease is a progressive neurodegenerative disease and the most common cause of dementia, where the accumulation and deposition of amyloid-β (Aβ) peptides cleaved from amyloid precursor protein (APP) in the brain trigger the pathogenic cascade of the disease. In consistence with human genetic studies, increasing evidence has demonstrated that ABCA7 deficiency exacerbates Aβ pathology using in vitro and in vivo models. While ABCA7 has been shown to mediate phagocytic activity in macrophages, ABCA7 is also involved in the microglial Aβ clearance pathway. Furthermore, ABCA7 deficiency results in accelerated Aβ production, likely by facilitating endocytosis and/or processing of APP. Taken together, current evidence suggests that ABCA7 loss-of-function contributes to AD-related phenotypes through multiple pathways. A better understanding of the function of ABCA7 beyond lipid metabolism in both physiological and pathological conditions becomes increasingly important to explore AD pathogenesis.

scholarly journals Preliminary Data on the Interaction between Some Biometals and Oxidative Stress Status in Mild Cognitive Impairment and Alzheimer’s Disease Patients

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Ioana-Miruna Balmuș ◽  
Stefan-Adrian Strungaru ◽  
Alin Ciobica ◽  
Mircea-Nicusor Nicoara ◽  
Romeo Dobrin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Lipid Peroxidation ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Association Studies ◽  
Metal Ion Homeostasis ◽  
Brain Functions ◽  
And Oxidative Stress

Increased interest regarding the biometal mechanisms of action and the pathways in which they have regulatory roles was lately observed. Particularly, it was shown that biometal homeostasis dysregulation may lead to neurodegeneration including Alzheimer’s disease, Parkinson disease, or prion protein disease, since important molecular signaling mechanisms in brain functions implicate both oxidative stress and redox active biometals. Oxidative stress could be a result of a breakdown in metal-ion homeostasis which leads to abnormal metal protein chelation. In our previous work, we reported a strong correlation between Alzheimer’s disease and oxidative stress. Consequently, the aim of the present work was to evaluate some of the biometals’ levels (magnesium, manganese, and iron), the specific activity of some antioxidant enzymes (superoxide dismutase and glutathione peroxidase), and a common lipid peroxidation marker (malondialdehyde concentration), in mild cognitive impairment (n=15) and Alzheimer’s disease (n=15) patients, compared to age-matched healthy subjects (n=15). We found increased lipid peroxidation effects, low antioxidant defense, low magnesium and iron concentrations, and high manganese levels in mild cognitive impairment and Alzheimer’s disease patients, in a gradual manner. These data could be relevant for future association studies regarding the prediction of Alzheimer’s disease development risk or circling through stages by analyzing both active redox metals, oxidative stress markers, and the correlations in between.

scholarly journals The Role of Butyrylcholinesterase and Iron in the Regulation of Cholinergic Network and Cognitive Dysfunction in Alzheimer’s Disease Pathogenesis

2021 ◽  
Vol 22 (4) ◽  
pp. 2033
Author(s):  
Jacek Jasiecki ◽  
Monika Targońska ◽  
Bartosz Wasąg
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Iron Homeostasis ◽  
Clinical Signs ◽  
Amyloid Β ◽  
Amyloid Plaques ◽  
Postmortem Brain ◽  
Brain Iron ◽  
Brain Functions

Alzheimer’s disease (AD), the most common form of dementia in elderly individuals, is marked by progressive neuron loss. Despite more than 100 years of research on AD, there is still no treatment to cure or prevent the disease. High levels of amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain are neuropathological hallmarks of AD. However, based on postmortem analyses, up to 44% of individuals have been shown to have high Aβ deposits with no clinical signs, due to having a “cognitive reserve”. The biochemical mechanism explaining the prevention of cognitive impairment in the presence of Aβ plaques is still unknown. It seems that in addition to protein aggregation, neuroinflammatory changes associated with aging are present in AD brains that are correlated with a higher level of brain iron and oxidative stress. It has been shown that iron accumulates around amyloid plaques in AD mouse models and postmortem brain tissues of AD patients. Iron is required for essential brain functions, including oxidative metabolism, myelination, and neurotransmitter synthesis. However, an imbalance in brain iron homeostasis caused by aging underlies many neurodegenerative diseases. It has been proposed that high iron levels trigger an avalanche of events that push the progress of the disease, accelerating cognitive decline. Patients with increased amyloid plaques and iron are highly likely to develop dementia. Our observations indicate that the butyrylcholinesterase (BChE) level seems to be iron-dependent, and reports show that BChE produced by reactive astrocytes can make cognitive functions worse by accelerating the decay of acetylcholine in aging brains. Why, even when there is a genetic risk, do symptoms of the disease appear after many years? Here, we discuss the relationship between genetic factors, age-dependent iron tissue accumulation, and inflammation, focusing on AD.

scholarly journals New Insights into the Molecular Bases of Familial Alzheimer’s Disease

2020 ◽  
Vol 10 (2) ◽  
pp. 26 ◽  
Author(s):  
Valeria D’Argenio ◽  
Daniela Sarnataro
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Protein Misfolding ◽  
Association Studies ◽  
Genome Wide Association Studies ◽  
App Processing ◽  
Rare Mutations ◽  
Genome Wide ◽  
Molecular Bases ◽  
The Brain

Like several neurodegenerative disorders, such as Prion and Parkinson diseases, Alzheimer’s disease (AD) is characterized by spreading mechanism of aggregated proteins in the brain in a typical “prion-like” manner. Recent genetic studies have identified in four genes associated with inherited AD (amyloid precursor protein-APP, Presenilin-1, Presenilin-2 and Apolipoprotein E), rare mutations which cause dysregulation of APP processing and alterations of folding of the derived amyloid beta peptide (Aβ). Accumulation and aggregation of Aβ in the brain can trigger a series of intracellular events, including hyperphosphorylation of tau protein, leading to the pathological features of AD. However, mutations in these four genes account for a small of the total genetic risk for familial AD (FAD). Genome-wide association studies have recently led to the identification of additional AD candidate genes. Here, we review an update of well-established, highly penetrant FAD-causing genes with correlation to the protein misfolding pathway, and novel emerging candidate FAD genes, as well as inherited risk factors. Knowledge of these genes and of their correlated biochemical cascade will provide several potential targets for treatment of AD and aging-related disorders.

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