Alzheimer’s Disease Genetics: A Dampened Microglial Response?

2021 ◽  
pp. 107385842110245
Author(s):  
Zena K. Chatila ◽  
Elizabeth M. Bradshaw
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Innate Immune ◽  
Regulatory Mechanisms ◽  
Innate Immune Cells ◽  
Genetic Studies ◽  
Age Related ◽  
Microglial Phenotype ◽  
The Central Nervous System ◽  
Microglial Response

Alzheimer’s disease (AD) is a debilitating age-related neurodegenerative condition. Unbiased genetic studies have implicated a central role for microglia, the resident innate immune cells of the central nervous system, in AD pathogenesis. On-going efforts are clarifying the biology underlying these associations and the microglial pathways that are dysfunctional in AD. Several genetic risk factors converge to decrease the function of activating microglial receptors and increase the function of inhibitory receptors, resulting in a seemingly dampened microglial phenotype in AD. Moreover, many of these microglial proteins that are genetically associated with AD appear to interact and share pathways or regulatory mechanisms, presenting several points of convergence that may be strategic targets for therapeutic intervention. Here, we review some of these studies and their implications for microglial participation in AD pathogenesis.

scholarly journals The Innate Immune System in Alzheimer’s Disease

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Allal Boutajangout ◽  
Thomas Wisniewski
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Immune System ◽  
Innate Immune System ◽  
Late Onset ◽  
Innate Immune ◽  
Amyloid Angiopathy ◽  
Functional Variant ◽  
The Central Nervous System ◽  
Congophilic Amyloid Angiopathy

Alzheimer’s disease (AD) is the leading cause for dementia in the world. It is characterized by two biochemically distinct types of protein aggregates: amyloidβ(Aβ) peptide in the forms of parenchymal amyloid plaques and congophilic amyloid angiopathy (CAA) and aggregated tau protein in the form of intraneuronal neurofibrillary tangles (NFT). Several risk factors have been discovered that are associated with AD. The most well-known genetic risk factor for late-onset AD is apolipoprotein E4 (ApoE4) (Potter and Wisniewski (2012), and Verghese et al. (2011)). Recently, it has been reported by two groups independently that a rare functional variant (R47H) of TREM2 is associated with the late-onset risk of AD. TREM2 is expressed on myeloid cells including microglia, macrophages, and dendritic cells, as well as osteoclasts. Microglia are a major part of the innate immune system in the CNS and are also involved in stimulating adaptive immunity. Microglia express several Toll-like receptors (TLRs) and are the resident macrophages of the central nervous system (CNS). In this review, we will focus on the recent advances regarding the role of TREM2, as well as the effects of TLRs 4 and 9 on AD.

scholarly journals Neuroinflammation characterizes the earliest changes in Alzheimer’s disease pathology and associated subjective cognitive impairment in adult hydrocephalus biopsies

2020 ◽  
Author(s):  
Wenrui Huang ◽  
Anne Marie Bartosch ◽  
Harrison Xiao ◽  
Xena Flowers ◽  
Sandra Leskinen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Status ◽  
Subjective Cognitive Decline ◽  
Cognitive Symptoms ◽  
Microglial Phenotype ◽  
Neuronal Genes ◽  
Early Alzheimer’S Disease ◽  
Disease Associated Genes ◽  
Microglial Response

AbstractIn an effort to better characterize the transcriptomic changes that accompany early Alzheimer’s disease (AD) pathology in living patients and correlate with contemporaneous cognitive data, we performed RNA-seq on 106 cortical biopsies that were taken during shunt placement for adult onset hydrocephalus with varying degrees of comorbid AD pathology. A restricted set of genes correlate with AD pathology in these biopsies, and co-expression network analysis demonstrates an evolution from microglial homeostasis to a disease-associated microglial phenotype in conjunction with increasing AD pathologic burden, along with a subset of additional astrocytic and neuronal genes that accompany these changes. Further analysis demonstrates that these correlations are driven by patients that report mild cognitive symptoms, despite similar levels of β-amyloid and tau pathology in comparison to patients who report no cognitive symptoms. Interestingly, downregulation of homeostatic genes and upregulation of disease-associated genes also correlate with microglial plaque invasion and an activated microglial morphology, and this change is not sensitive to cognitive status, suggesting that an initial microglial response to AD pathology is eventually maladaptive. Taken together, these findings highlight a restricted set of microglial and non-microglial genes and suggest that early AD pathology is largely characterized by a loss of homeostatic genes and an activated microglial phenotype that continues to evolve in conjunction with accumulating AD pathology in the setting of subjective cognitive decline.

scholarly journals Immunohistochemical Study of ASC Expression and Distribution in the Hippocampus of an Aged Murine Model of Alzheimer’s Disease

2021 ◽  
Vol 22 (16) ◽  
pp. 8697
Author(s):  
Diana Reimers ◽  
Manuela Vallejo-Muñoz ◽  
María José Casarejos ◽  
Adriano Jimenez-Escrig ◽  
Rafael Gonzalo-Gobernado ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Immune Cells ◽  
Immunohistochemical Study ◽  
Transgenic Mouse Model ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Danger Signals ◽  
Model Of Alzheimer’S Disease ◽  
Pro Inflammatory Cytokines

Neuroinflammation is involved in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease (AD), and is notably dependent on age. One important inflammatory pathway exerted by innate immune cells of the nervous system in response to danger signals is mediated by inflammasomes (IF) and leads to the generation of potent pro-inflammatory cytokines. The protein “apoptosis-associated speck-like protein containing a caspase recruitment domain” (ASC) modulates IF activation but has also other functions which are crucial in AD. We intended to characterize immunohistochemically ASC and pattern recognition receptors (PRR) of IF in the hippocampus (HP) of the transgenic mouse model Tg2576 (APP), in which amyloid-beta (Aβ) pathology is directly dependent on age. We show in old-aged APP a significant amount of ASC in microglia and astrocytes associated withAβ plaques, in the absence of PRR described by others in glial cells. In addition, APP developed foci with clusters of extracellular ASC granules not spatiallyrelated to Aβ plaques, which density correlated with the advanced age of mice and AD development. Clusters were associated withspecific astrocytes characterized by their enlarged ring-shaped process terminals, ASC content, and frequent perivascular location. Their possible implication in ASC clearance and propagation of inflammation is discussed.

scholarly journals Immunotherapeutic Strategies for Alzheimer's Disease Treatment

2009 ◽  
Vol 9 ◽  
pp. 909-919 ◽  
Author(s):  
Beka Solomon
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Passive Immunization ◽  
Amyloid Β ◽  
Amyloid Β Peptide ◽  
Disease Treatment ◽  
Naturally Occurring ◽  
Age Related ◽  
The Central Nervous System ◽  
Naturally Occurring Antibodies

Naturally occurring antibodies against amyloid-β peptides have been found in human cerebrospinal fluid and in the plasma of healthy individuals, but were significantly lower in Alzheimer's disease (AD) patients, suggesting that AD may be an immunodeficient disorder. The performance of anti-amyloid-β antibodies in transgenic mice models of AD showed that they are delivered to the central nervous system, preventing and dissolving amyloid-β plaques. Moreover, these antibodies protected the mice from learning and age-related memory deficits. Active and/or passive immunization against the amyloid-β peptide has been proposed as a method for preventing and/or treating AD. Immunotherapy represents fascinating ways to test the amyloid hypothesis and offers genuine opportunities for AD treatment, but requires careful antigen and antibody selection to maximize efficacy and minimize adverse events.

scholarly journals Microglia in Aging and Alzheimer’s Disease: A Comparative Species Review

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1138
Author(s):  
Melissa K. Edler ◽  
Isha Mhatre-Winters ◽  
Jason R. Richardson
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Animal Models ◽  
Single Species ◽  
Functional Behavior ◽  
Age Related ◽  
Rapid Changes ◽  
The Central Nervous System ◽  
Oxidative Species ◽  
Selection Of

Microglia are the primary immune cells of the central nervous system that help nourish and support neurons, clear debris, and respond to foreign stimuli. Greatly impacted by their environment, microglia go through rapid changes in cell shape, gene expression, and functional behavior during states of infection, trauma, and neurodegeneration. Aging also has a profound effect on microglia, leading to chronic inflammation and an increase in the brain’s susceptibility to neurodegenerative processes that occur in Alzheimer’s disease. Despite the scientific community’s growing knowledge in the field of neuroinflammation, the overall success rate of drug treatment for age-related and neurodegenerative diseases remains incredibly low. Potential reasons for the lack of translation from animal models to the clinic include the use of a single species model, an assumption of similarity in humans, and ignoring contradictory data or information from other species. To aid in the selection of validated and predictive animal models and to bridge the translational gap, this review evaluates similarities and differences among species in microglial activation and density, morphology and phenotype, cytokine expression, phagocytosis, and production of oxidative species in aging and Alzheimer’s disease.

scholarly journals Mild Microglial Responses in the Cortex and Perivascular Macrophage Infiltration in Subcortical White Matter in Dogs with Age-Related Dementia Modelling Prodromal Alzheimer’s Disease

2021 ◽  
pp. 1-18
Author(s):  
Barbara Blicher Thomsen ◽  
Cecilie Madsen ◽  
Katrine Tækker Krohn ◽  
Camilla Thygesen ◽  
Trine Schütt ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
White Matter ◽  
Subcortical White Matter ◽  
Cortical Layers ◽  
Rating Score ◽  
Perivascular Macrophage ◽  
Age Related ◽  
Prodromal Ad ◽  
Microglial Response

Background: Microglia contribute to Alzheimer’s disease (AD) pathogenesis by clearing amyloid-β (Aβ) and driving neuroinflammation. Domestic dogs with age-related dementia (canine cognitive dysfunction (CCD)) develop cerebral amyloidosis like humans developing AD, and studying such dogs can provide novel information about microglial response in prodromal AD. Objective: The aim was to investigate the microglial response in the cortical grey and the subcortical white matter in dogs with CCD versus age-matched cognitively normal dogs. Methods: Brains from aged dogs with CCD and age-matched controls without dementia were studied. Cases were defined by dementia rating score. Brain sections were stained for Aβ, thioflavin S, hyperphosphorylated tau, and the microglial-macrophage ionized calcium binding adaptor molecule 1 (Iba1). Results were correlated to dementia rating score and tissue levels of Aβ. Results: Microglial numbers were higher in the Aβ plaque-loaded deep cortical layers in CCD versus control dogs, while the coverage by microglial processes were comparable. Aβ plaques were of the diffuse type and without microglial aggregation. However, a correlation was found between the %Iba1 area and insoluble Aβ 42 and N-terminal pyroglutamate modified Aβ(N3pE)-42. The %Iba1 area was higher in white matter, showing phosphorylation of S396 tau, versus grey matter. Perivascular macrophage infiltrates were abundant in the white matter particularly in CDD dogs. Conclusion: The results from this study of the microglial-macrophage response in dogs with CCD are suggestive of relatively mild microglial responses in the Aβ plaque-loaded deep cortical layers and perivascular macrophage infiltrates in the subcortical white matter, in prodromal AD.

scholarly journals Triggering Innate Immune Receptors as New Therapies in Alzheimer’s Disease and Multiple Sclerosis

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 2164
Author(s):  
Pierre-Alexandre Piec ◽  
Vincent Pons ◽  
Serge Rivest
Keyword(s):  
Multiple Sclerosis ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Innate Immunity ◽  
Immune Cells ◽  
Therapeutic Potential ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Disease Course ◽  
Beneficial Effects

Multiple sclerosis and Alzheimer’s disease are two complex neurodegenerative diseases involving the immune system. So far, available treatments provide at best mild improvements to patients’ conditions. For decades now, a new set of molecules have been used to modulate and regulate the innate immunity in these pathologies. Most studies have been carried out in rodents and some of them have reported tremendous beneficial effects on the disease course. The modulation of innate immune cells is of great interest since it provides new hope for patients. In this review, we will briefly overview the therapeutic potential of some molecules and receptors in multiple sclerosis and Alzheimer’s disease and how they could be used to exploit new therapeutic avenues.

scholarly journals Microglial translational profiling reveals a convergent APOE pathway from aging, amyloid, and tau

2018 ◽  
Vol 215 (9) ◽  
pp. 2235-2245 ◽  
Author(s):  
Silvia S. Kang ◽  
Mark T.W. Ebbert ◽  
Kelsey E. Baker ◽  
Casey Cook ◽  
Xuewei Wang ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Neurodegenerative Disease ◽  
Immune Cells ◽  
Cell Sorting ◽  
Innate Immune ◽  
Innate Immune Cells ◽  
Potential Mechanism ◽  
The Brain

Alzheimer’s disease (AD) is an age-associated neurodegenerative disease characterized by amyloidosis, tauopathy, and activation of microglia, the brain resident innate immune cells. We show that a RiboTag translational profiling approach can bypass biases due to cellular enrichment/cell sorting. Using this approach in models of amyloidosis, tauopathy, and aging, we revealed a common set of alterations and identified a central APOE-driven network that converged on CCL3 and CCL4 across all conditions. Notably, aged females demonstrated a significant exacerbation of many of these shared transcripts in this APOE network, revealing a potential mechanism for increased AD susceptibility in females. This study has broad implications for microglial transcriptomic approaches and provides new insights into microglial pathways associated with different pathological aspects of aging and AD.

scholarly journals Biomarkers for Microglial Activation in Alzheimer's Disease

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Ronald Lautner ◽  
Niklas Mattsson ◽  
Michael Schöll ◽  
Kristin Augutis ◽  
Kaj Blennow ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Microglial Activation ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
First Line ◽  
The Central Nervous System ◽  
Underlying Mechanisms ◽  
The Brain ◽  
Neuroimaging Techniques

Intensive research over the last decades has provided increasing evidence for neuroinflammation as an integral part in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD). Inflammatory responses in the central nervous system (CNS) are initiated by activated microglia, representing the first line of the innate immune defence of the brain. Therefore, biochemical markers of microglial activation may help us understand the underlying mechanisms of neuroinflammation in AD as well as the double-sided qualities of microglia, namely, neuroprotection and neurotoxicity. In this paper we summarize candidate biomarkers of microglial activation in AD along with a survey of recent neuroimaging techniques.

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