Disease specific alterations in the olfactory mucosa of patients with Alzheimer’s disease

ABSTRACTOlfactory dysfunction manifests in early stages of neurodegeneration in several disorders of the central nervous system. The sense of smell is orchestrated by the cells of the olfactory mucosa located in the upper nasal cavity, however, it is unclear how this tissue reflects key neurodegenerative features in Alzheimer’s disease (AD). Here we report that olfactory mucosa (OM) cells of patients with AD secrete increased amounts of toxic amyloid-beta. We detail cell-type specific gene expression patterns, unveiling 154 differentially expressed AD-associated genes compared to the cognitively normal controls, and 5 distinct cell populations in the cultures, together with disease-associated subpopulations. Overall, coordinated alteration of RNA and protein metabolism, inflammatory processes and signal transduction were observed in multiple cell types, suggesting a key role in AD pathophysiology. Our results demonstrate the potential of OM cultures as a new cellular model for AD. Moreover, for the first time we provide single cell transcript data for investigating the molecular and cellular mechanisms of AD in the OM.

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Metabolism-Based Gene Differences in Neurons Expressing Hyperphosphorylated AT8− Positive (AT8+) Tau in Alzheimer’s Disease

ASN NEURO ◽

10.1177/17590914211019443 ◽

2021 ◽

Vol 13 ◽

pp. 175909142110194

Author(s):

Audra York ◽

Angela Everhart ◽

Michael P. Vitek ◽

Kirby W. Gottschalk ◽

Carol A. Colton

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Metabolic Pathways ◽

Cell Types ◽

Specific Protein ◽

Specific Gene ◽

Specific Cell ◽

Mrna Levels ◽

Double Labeling ◽

Expression Levels

Metabolic adaptations in the brain are critical to the establishment and maintenance of normal cellular functions and to the pathological responses to disease processes. Here, we have focused on specific metabolic pathways that are involved in immune-mediated neuronal processes in brain using isolated neurons derived from human autopsy brain sections of normal individuals and individuals diagnosed as Alzheimer’s disease (AD). Laser capture microscopy was used to select specific cell types in immune-stained thin brain sections followed by NanoString technology to identify and quantify differences in mRNA levels between age-matched control and AD neuronal samples. Comparisons were also made between neurons isolated from AD brain sections expressing pathogenic hyperphosphorylated AT8- positive (AT8+) tau and non-AT8+ AD neurons using double labeling techniques. The mRNA expression data showed unique patterns of metabolic pathway expression between the subtypes of captured neurons that involved membrane based solute transporters, redox factors, and arginine and methionine metabolic pathways. We also identified the expression levels of a novel metabolic gene, Radical-S-Adenosyl Domain1 ( RSAD1) and its corresponding protein, Rsad1, that impact methionine usage and radical based reactions. Immunohistochemistry was used to identify specific protein expression levels and their cellular location in NeuN+ and AT8+ neurons. APOE4 vs APOE3 genotype-specific and sex-specific gene expression differences in these metabolic pathways were also observed when comparing neurons from individuals with AD to age-matched individuals.

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Microglia Mediate the Occurrence and Development of Alzheimer’s Disease Through Ligand-Receptor Axis Communication

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.731180 ◽

2021 ◽

Vol 13 ◽

Author(s):

Chongdong Jian ◽

Lei Wei ◽

Ruikang Mo ◽

Rongjie Li ◽

Lucong Liang ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Logistic Regression ◽

Glial Cells ◽

Cell Types ◽

Support Vector ◽

Marker Genes ◽

Cell Type ◽

Communication Analysis ◽

Cellular Mechanisms

Alzheimer’s disease (AD) is a common neurodegenerative disease. Its onset is insidious and its progression is slow, making diagnosis difficult. In addition, its underlying molecular and cellular mechanisms remain unclear. In this study, clustering analysis was performed on single-cell RNA sequencing (scRNA-seq) data from the prefrontal cortex of 48 AD patients. Each sample module was identified to be a specific AD cell type, eight main brain cell types were identified, and the dysfunctional evolution of each cell type was further explored by pseudo-time analysis. Correlation analysis was then used to explore the relationship between AD cell types and pathological characteristics. In particular, intercellular communication between neurons and glial cells in AD patients was investigated by cell communication analysis. In patients, neuronal cells and glial cells significantly correlated with pathological features, and glial cells appear to play a key role in the development of AD through ligand-receptor axis communication. Marker genes involved in communication between these two cell types were identified using five types of modeling: logistic regression, multivariate logistic regression, least absolute shrinkage and selection operator (LASSO) and support vector machine (SVM). LASSO modeling identified CXCR4, EGFR, MAP4K4, and IGF1R as key genes in this communication. Our results support the idea that microglia play a role in the occurrence and development of AD through ligand-receptor axis communication. In particular, our analyses identify CXCR4, EGFR, MAP4K4, and IGF1R as potential biomarkers and therapeutic targets in AD.

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Generation of APOE knock-down SK-N-SH human neuroblastoma cells using CRISPR/Cas9: a novel cellular model relevant to Alzheimer’s disease research

Bioscience Reports ◽

10.1042/bsr20204243 ◽

2021 ◽

Vol 41 (2) ◽

Author(s):

Sonia Sanz Muñoz ◽

Brett Garner ◽

Lezanne Ooi

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neuroblastoma Cells ◽

Cell Types ◽

Human Neuroblastoma ◽

Multiple Cell ◽

Fragmentation Patterns ◽

The Brain ◽

Precise Role ◽

Apoe Expression

Abstract APOE ε4 is the major genetic risk factor for Alzheimer’s disease (AD). A precise role for apolipoprotein E (apoE) in the pathogenesis of the disease remains unclear in part due to its expression in multiple cell types of the brain. APOE is highly expressed in astrocytes and microglia, however its expression can also be induced in neurons under various conditions. The neuron-like cell line SK-N-SH is a useful model in the study of the cellular and molecular effects of apoE as it can be differentiated with retinoic acid to express and secrete high levels of apoE and it also shows the same apoE fragmentation patterns observed in the human brain. We previously found that apoE is cleaved into a 25-kDa fragment by high temperature-requirement serine protease A1 (HtrA1) in SK-N-SH cells. To further understand the endogenous functions of apoE, we used CRISPR/Cas9 to generate SK-N-SH cell lines with APOE expression knocked-down (KD). APOE KD cells showed lower APOE and HTRA1 expression than parental SK-N-SH cells but no overt differences in neuritogenesis or cell proliferation compared with the CRISPR/Cas9 control cells. This research shows that the loss of apoE and HtrA1 has a negligible effect on neuritogenesis and cell survival in SK-N-SH neuron-like cells.

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Transcriptome and Translatome Regulation of Pathogenesis in Alzheimer’s Disease Model Mice

Journal of Alzheimer s Disease ◽

10.3233/jad-215357 ◽

2022 ◽

pp. 1-22

Author(s):

Guillermo Eastman ◽

Elizabeth R. Sharlow ◽

John S. Lazo ◽

George S. Bloom ◽

José R. Sotelo-Silveira

Keyword(s):

Gene Expression ◽

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Expression Patterns ◽

Regulation Of Gene Expression ◽

Ribosome Profiling ◽

Mouse Strains ◽

Translational Efficiency ◽

Rna Seq ◽

Cellular Mechanisms

Background: Defining cellular mechanisms that drive Alzheimer’s disease (AD) pathogenesis and progression will be aided by studies defining how gene expression patterns change during pre-symptomatic AD and ensuing periods of declining cognition. Previous studies have emphasized changes in transcriptome, but not translatome regulation, leaving the ultimate results of gene expression alterations relatively unexplored in the context of AD. Objective: To identify genes whose expression might be regulated at the transcriptome and translatome levels in AD, we analyzed gene expression in cerebral cortex of two AD model mouse strains, CVN (APPSwDI;NOS2 -/- ) and Tg2576 (APPSw), and their companion wild type (WT) strains at 6 months of age by tandem RNA-Seq and Ribo-Seq (ribosome profiling). Methods: Identical starting pools of bulk RNA were used for RNA-Seq and Ribo-Seq. Differential gene expression analysis was performed at the transcriptome, translatome, and translational efficiency levels. Regulated genes were functionally evaluated by gene ontology tools. Results: Compared to WT mice, AD model mice had similar levels of transcriptome regulation, but differences in translatome regulation. A microglial signature associated with early stages of Aβ accumulation was upregulated at both levels in CVN mice. Although the two mice strains did not share many regulated genes, they showed common regulated pathways related to AβPP metabolism associated with neurotoxicity and neuroprotection. Conclusion: This work represents the first genome-wide study of brain translatome regulation in animal models of AD and provides evidence of a tight and early translatome regulation of gene expression controlling the balance between neuroprotective and neurodegenerative processes in brain.

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An Overview of Astrocyte Responses in Genetically Induced Alzheimer’s Disease Mouse Models

Cells ◽

10.3390/cells9112415 ◽

2020 ◽

Vol 9 (11) ◽

pp. 2415

Author(s):

Fokion Spanos ◽

Shane A. Liddelow

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Mouse Models ◽

Cell Types ◽

Functional Changes ◽

New Methods ◽

Metabolic Functions ◽

The Central Nervous System ◽

Multiple Cell ◽

The Many

Alzheimer’s disease (AD) is the most common form of dementia. Despite many years of intense research, there is currently still no effective treatment. Multiple cell types contribute to disease pathogenesis, with an increasing body of data pointing to the active participation of astrocytes. Astrocytes play a pivotal role in the physiology and metabolic functions of neurons and other cells in the central nervous system. Because of their interactions with other cell types, astrocyte functions must be understood in their biologic context, thus many studies have used mouse models, of which there are over 190 available for AD research. However, none appear able to fully recapitulate the many functional changes in astrocytes reported in human AD brains. Our review summarizes the observations of astrocyte biology noted in mouse models of familial and sporadic AD. The limitations of AD mouse models will be discussed and current attempts to overcome these disadvantages will be described. With increasing understanding of the non-neuronal contributions to disease, the development of new methods and models will provide further insights and address important questions regarding the roles of astrocytes and other non-neuronal cells in AD pathophysiology. The next decade will prove to be full of exciting opportunities to address this devastating disease.

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A human brain vascular atlas reveals diverse cell mediators of Alzheimer’s disease risk

10.1101/2021.04.26.441262 ◽

2021 ◽

Author(s):

Andrew C. Yang ◽

Ryan T. Vest ◽

Fabian Kern ◽

Davis P. Lee ◽

Christina A. Maat ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Human Brain ◽

Protein Transport ◽

Disease Risk ◽

Expression Patterns ◽

Cell Types ◽

Mural Cell ◽

Perivascular Cell ◽

Brain Vasculature

AbstractThe human brain vasculature is of vast medical importance: its dysfunction causes disability and death, and the specialized structure it forms—the blood-brain barrier—impedes treatment of nearly all brain disorders. Yet, no molecular atlas of the human brain vasculature exists. Here, we develop Vessel Isolation and Nuclei Extraction for Sequencing (VINE-seq) to profile the major human brain vascular and perivascular cell types through 143,793 single-nucleus transcriptomes from 25 hippocampus and cortex samples of 17 control and Alzheimer’s disease (AD) patients. We identify brain region-enriched pathways and genes divergent between humans and mice, including those involved in disease. We describe the principles of human arteriovenous organization, recapitulating a gradual endothelial and punctuated mural cell continuum; but discover that many zonation and cell-type markers differ between species. We discover two subtypes of human pericytes, marked by solute transport and extracellular matrix (ECM) organization; and define perivascular versus meningeal fibroblast specialization. In AD, we observe a selective vulnerability of ECM-maintaining pericytes and gene expression patterns implicating dysregulated blood flow. With an expanded survey of brain cell types, we find that 30 of the top 45 AD GWAS genes are expressed in the human brain vasculature, confirmedin situ. Vascular GWAS genes map to endothelial protein transport, adaptive immune, and ECM pathways. Many are microglia-specific in mice, suggesting an evolutionary transfer of AD risk to human vascular cells. Our work unravels the molecular basis of the human brain vasculature, informing our understanding of overall brain health, disease, and therapy.

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Shared Blood Transcriptomic Signatures between Alzheimer’s Disease and Diabetes Mellitus

Biomedicines ◽

10.3390/biomedicines9010034 ◽

2021 ◽

Vol 9 (1) ◽

pp. 34

Author(s):

Taesic Lee ◽

Hyunju Lee

Keyword(s):

Diabetes Mellitus ◽

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Protein Interactions ◽

Expression Patterns ◽

Protein Protein Interactions ◽

Hub Genes ◽

Gene Modules ◽

Gene Regulatory ◽

The Brain

Alzheimer’s disease (AD) and diabetes mellitus (DM) are known to have a shared molecular mechanism. We aimed to identify shared blood transcriptomic signatures between AD and DM. Blood expression datasets for each disease were combined and a co-expression network was used to construct modules consisting of genes with similar expression patterns. For each module, a gene regulatory network based on gene expression and protein-protein interactions was established to identify hub genes. We selected one module, where COPS4, PSMA6, GTF2B, GTF2F2, and SSB were identified as dysregulated transcription factors that were common between AD and DM. These five genes were also differentially co-expressed in disease-related tissues, such as the brain in AD and the pancreas in DM. Our study identified gene modules that were dysregulated in both AD and DM blood samples, which may contribute to reveal common pathophysiology between two diseases.

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Neuropathology of the Brainstem to Mechanistically Understand and to Treat Alzheimer’s Disease

Journal of Clinical Medicine ◽

10.3390/jcm10081555 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1555

Author(s):

Ágoston Patthy ◽

János Murai ◽

János Hanics ◽

Anna Pintér ◽

Péter Zahola ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cortical Neurons ◽

Molecular Mechanisms ◽

Neurodegenerative Disorder ◽

Brain Structures ◽

Specific Information ◽

Cellular Mechanisms ◽

Monoaminergic System ◽

Monoaminergic Neurons

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder as yet without effective therapy. Symptoms of this disorder typically reflect cortical malfunction with local neurohistopathology, which biased investigators to search for focal triggers and molecular mechanisms. Cortex, however, receives massive afferents from caudal brain structures, which do not only convey specific information but powerfully tune ensemble activity. Moreover, there is evidence that the start of AD is subcortical. The brainstem harbors monoamine systems, which establish a dense innervation in both allo- and neocortex. Monoaminergic synapses can co-release neuropeptides either by precisely terminating on cortical neurons or, when being “en passant”, can instigate local volume transmission. Especially due to its early damage, malfunction of the ascending monoaminergic system emerges as an early sign and possible trigger of AD. This review summarizes the involvement and cascaded impairment of brainstem monoaminergic neurons in AD and discusses cellular mechanisms that lead to their dysfunction. We highlight the significance and therapeutic challenges of transmitter co-release in ascending activating system, describe the role and changes of local connections and distant afferents of brainstem nuclei in AD, and summon the rapidly increasing diagnostic window during the last few years.

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Microglial Function and Regulation during Development, Homeostasis and Alzheimer’s Disease

Cells ◽

10.3390/cells10040957 ◽

2021 ◽

Vol 10 (4) ◽

pp. 957

Author(s):

Brad T. Casali ◽

Erin G. Reed-Geaghan

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Immune Cells ◽

Expression Patterns ◽

Brain Parenchyma ◽

Primary Role ◽

And Function ◽

Inflammatory Milieu ◽

The Brain ◽

Homeostatic State

Microglia are the resident immune cells of the brain, deriving from yolk sac progenitors that populate the brain parenchyma during development. During development and homeostasis, microglia play critical roles in synaptogenesis and synaptic plasticity, in addition to their primary role as immune sentinels. In aging and neurodegenerative diseases generally, and Alzheimer’s disease (AD) specifically, microglial function is altered in ways that significantly diverge from their homeostatic state, inducing a more detrimental inflammatory environment. In this review, we discuss the receptors, signaling, regulation and gene expression patterns of microglia that mediate their phenotype and function contributing to the inflammatory milieu of the AD brain, as well as strategies that target microglia to ameliorate the onset, progression and symptoms of AD.

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The role of neuroglial metabotropic glutamate receptors in Alzheimer's disease

Current Neuropharmacology ◽

10.2174/1570159x19666210916102638 ◽

2021 ◽

Vol 19 ◽

Author(s):

Khaled S. Abd-Elrahman ◽

Shaarika Sarasija ◽

Stephen S. G. Ferguson

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Glutamate Receptors ◽

Metabotropic Glutamate Receptors ◽

Expression Patterns ◽

Neuronal Cell ◽

Hyperphosphorylated Tau ◽

Metabotropic Glutamate ◽

Group I ◽

The Brain

: Glutamate, the major excitatory neurotramitter in the brain exerts its effects via both ionotropic glutamate receptors and metabotropic glutamate receptors (mGluRs). There are three subgroups of mGluRs, pre-synaptic Group II and Group III mGluRs and post-synaptic Group I mGluRs. mGluRs are ubiquitously expressed in the brain and their activation is poised upstream of a myriad of signaling pathways, resulting in their implication in the pathogenesis of various neurodegenerative diseases including, Alzheimer’s disease (AD). While the exact mechanism of AD etiology remains elusive, β-amyloid (Aβ) plaques and hyperphosphorylated tau tangles remain the histopathological hallmarks of AD. Though less electrically excitable, neuroglia are a major non-neuronal cell type in the brain and are composed of astrocytes, microglia, and oligodendrocytes. Astrocytes, microglia, and oligodendrocytes provide structural and metabolic support, active immune defence, and axonal support and sheathing, respectively. Interestingly, Aβ and hyperphosphorylated tau are known to disrupt the neuroglial homeostasis in the brain, pushing them towards a more neurotoxic state. In this review, we discuss what is currently known regarding the expression patterns of various mGluRs in neuroglia and how Aβ and tau alter the normal mGluR function in the neuroglia and contribute to the pathophysiology of AD.

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