scholarly journals Activated microglia mitigate Aβ-associated tau seeding and spreading

2021 ◽  
Vol 218 (8) ◽  
Author(s):  
Maud Gratuze ◽  
Yun Chen ◽  
Samira Parhizkar ◽  
Nimansha Jain ◽  
Michael R. Strickland ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neuronal Loss ◽  
Gain Of Function ◽  
Aged Mice ◽  
Activated Microglia ◽  
Risk Variants ◽  
Neuritic Dystrophy

In Alzheimer’s disease (AD) models, AD risk variants in the microglial-expressed TREM2 gene decrease Aβ plaque–associated microgliosis and increase neuritic dystrophy as well as plaque-associated seeding and spreading of tau aggregates. Whether this Aβ-enhanced tau seeding/spreading is due to loss of microglial function or a toxic gain of function in TREM2-deficient microglia is unclear. Depletion of microglia in mice with established brain amyloid has no effect on amyloid but results in less spine and neuronal loss. Microglial repopulation in aged mice improved cognitive and neuronal deficits. In the context of AD pathology, we asked whether microglial removal and repopulation decreased Aβ-driven tau seeding and spreading. We show that both TREM2KO and microglial ablation dramatically enhance tau seeding and spreading around plaques. Interestingly, although repopulated microglia clustered around plaques, they had a reduction in disease-associated microglia (DAM) gene expression and elevated tau seeding/spreading. Together, these data suggest that TREM2-dependent activation of the DAM phenotype is essential in delaying Aβ-induced pathological tau propagation.

Consideration of a Pharmacological Combinatorial Approach to Inhibit Chronic Inflammation in Alzheimer’s Disease

2019 ◽  
Vol 16 (11) ◽  
pp. 1007-1017 ◽  
Author(s):  
James G. McLarnon
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Animal Models ◽  
Chronic Inflammation ◽  
Preventive Strategy ◽  
Subsequent Work ◽  
Activated Microglia ◽  
Starting Point ◽  
Anti Inflammatory ◽  
Cocktail Approach

A combinatorial cocktail approach is suggested as a rationale intervention to attenuate chronic inflammation and confer neuroprotection in Alzheimer’s disease (AD). The requirement for an assemblage of pharmacological compounds follows from the host of pro-inflammatory pathways and mechanisms present in activated microglia in the disease process. This article suggests a starting point using four compounds which present some differential in anti-inflammatory targets and actions but a commonality in showing a finite permeability through Blood-brain Barrier (BBB). A basis for firstchoice compounds demonstrated neuroprotection in animal models (thalidomide and minocycline), clinical trial data showing some slowing in the progression of pathology in AD brain (ibuprofen) and indirect evidence for putative efficacy in blocking oxidative damage and chemotactic response mediated by activated microglia (dapsone). It is emphasized that a number of candidate compounds, other than ones suggested here, could be considered as components of the cocktail approach and would be expected to be examined in subsequent work. In this case, systematic testing in AD animal models is required to rigorously examine the efficacy of first-choice compounds and replace ones showing weaker effects. This protocol represents a practical approach to optimize the reduction of microglial-mediated chronic inflammation in AD pathology. Subsequent work would incorporate the anti-inflammatory cocktail delivery as an adjunctive treatment with ones independent of inflammation as an overall preventive strategy to slow the progression of AD.

scholarly journals Defining early changes in Alzheimer’s disease from RNA sequencing of brain regions differentially affected by pathology

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Boris Guennewig ◽  
Julia Lim ◽  
Lee Marshall ◽  
Andrew N. McCorkindale ◽  
Patrick J. Paasila ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Rna Sequencing ◽  
Neuronal Loss ◽  
Brain Regions ◽  
Post Mortem ◽  
Tau Pathology ◽  
Membrane Spanning ◽  
Immune Related Genes ◽  
Vesicle Secretion

AbstractTau pathology in Alzheimer’s disease (AD) spreads in a predictable pattern that corresponds with disease symptoms and severity. At post-mortem there are cortical regions that range from mildly to severely affected by tau pathology and neuronal loss. A comparison of the molecular signatures of these differentially affected areas within cases and between cases and controls may allow the temporal modelling of disease progression. Here we used RNA sequencing to explore differential gene expression in the mildly affected primary visual cortex and moderately affected precuneus of ten age-, gender- and RNA quality-matched post-mortem brains from AD patients and healthy controls. The two regions in AD cases had similar transcriptomic signatures but there were broader abnormalities in the precuneus consistent with the greater tau load. Both regions were characterised by upregulation of immune-related genes such as those encoding triggering receptor expressed on myeloid cells 2 and membrane spanning 4-domains A6A and milder changes in insulin/IGF1 signalling. The precuneus in AD was also characterised by changes in vesicle secretion and downregulation of the interneuronal subtype marker, somatostatin. The ‘early’ AD transcriptome is characterised by perturbations in synaptic vesicle secretion on a background of neuroimmune dysfunction. In particular, the synaptic deficits that characterise AD may begin with the somatostatin division of inhibitory neurotransmission.

scholarly journals Association of neurogranin gene expression with Alzheimer's disease pathology in the perirhinal cortex

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xiaoyan Sun ◽  
Qian Wang ◽  
Kaj Blennow ◽  
Henrik Zetterberg ◽  
Micheline McCarthy ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Perirhinal Cortex

Lentivirus-Mediated Expression of Human Secreted Amyloid Precursor Protein-Alpha Promotes Long-Term Induction of Neuroprotective Genes and Pathways in a Mouse Model of Alzheimer’s Disease

2020 ◽  
pp. 1-16
Author(s):  
Margaret Ryan ◽  
Valerie T.Y. Tan ◽  
Nasya Thompson ◽  
Diane Guévremont ◽  
Bruce G. Mockett ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Amyloid Precursor Protein ◽  
Precursor Protein ◽  
Integrated Analysis ◽  
Empty Vector ◽  
Mouse Transcriptome

Background: Secreted amyloid precursor protein-alpha (sAPPα) can enhance memory and is neurotrophic and neuroprotective across a range of disease-associated insults, including amyloid-β toxicity. In a significant step toward validating sAPPα as a therapeutic for Alzheimer’s disease (AD), we demonstrated that long-term overexpression of human sAPPα (for 8 months) in a mouse model of amyloidosis (APP/PS1) could prevent the behavioral and electrophysiological deficits that develop in these mice. Objective: To explore the underlying molecular mechanisms responsible for the significant physiological and behavioral improvements observed in sAPPα-treated APP/PS1 mice. Methods: We assessed the long-term effects on the hippocampal transcriptome following continuous lentiviral delivery of sAPPα or empty-vector to male APP/PS1 mice and wild-type controls using Affymetrix Mouse Transcriptome Assays. Data analysis was carried out within the Affymetrix Transcriptome Analysis Console and an integrated analysis of the resulting transcriptomic data was performed with Ingenuity Pathway analysis (IPA). Results: Mouse transcriptome assays revealed expected AD-associated gene expression changes in empty-vector APP/PS1 mice, providing validation of the assays used for the analysis. By contrast, there were specific sAPPα-associated gene expression profiles which included increases in key neuroprotective genes such as Decorin, betaine-GABA transporter, and protocadherin beta-5, subsequently validated by qRT-PCR. An integrated biological pathways analysis highlighted regulation of GABA receptor signaling, cell survival, and inflammatory responses. Furthermore, upstream gene regulatory analysis implicated sAPPα activation of Interleukin-4, which can counteract inflammatory changes in AD. Conclusion: This study identified key molecular processes that likely underpin the long-term neuroprotective and therapeutic effects of increasing sAPPα levels in vivo

scholarly journals Transcriptomic analysis to identify genes associated with selective hippocampal vulnerability in Alzheimer’s disease

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Angela M. Crist ◽  
Kelly M. Hinkle ◽  
Xue Wang ◽  
Christina M. Moloney ◽  
Billie J. Matchett ◽  
...  
Keyword(s):  
Gene Expression ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Digital Pathology ◽  
Selective Vulnerability ◽  
Brain Regions ◽  
Biochemical Analyses ◽  
The Brain ◽  
Relevant Gene ◽  
Tau Expression

AbstractSelective vulnerability of different brain regions is seen in many neurodegenerative disorders. The hippocampus and cortex are selectively vulnerable in Alzheimer’s disease (AD), however the degree of involvement of the different brain regions differs among patients. We classified corticolimbic patterns of neurofibrillary tangles in postmortem tissue to capture extreme and representative phenotypes. We combined bulk RNA sequencing with digital pathology to examine hippocampal vulnerability in AD. We identified hippocampal gene expression changes associated with hippocampal vulnerability and used machine learning to identify genes that were associated with AD neuropathology, including SERPINA5, RYBP, SLC38A2, FEM1B, and PYDC1. Further histologic and biochemical analyses suggested SERPINA5 expression is associated with tau expression in the brain. Our study highlights the importance of embracing heterogeneity of the human brain in disease to identify disease-relevant gene expression.

Sign in / Sign up

Export Citation Format

Share Document