Role of TREM2 in Alzheimer's Disease and its Consequences on β- Amyloid, Tau and Neurofibrillary Tangles

2020 ◽  
Vol 16 (13) ◽  
pp. 1216-1229 ◽  
Author(s):  
Anurag K. Singh ◽  
Gaurav Mishra ◽  
Anand Maurya ◽  
Rajendra Awasthi ◽  
Komal Kumari ◽  
...  

: Alzheimer's Disease (AD) is age-related neurodegenerative disorder recognized by a steadily gradual cognitive decline that has devastating personal and socioeconomic implications. Recently, some genetic factors for AD have been identified which attracted wide attention of researchers in different areas of AD biology and possible new therapeutic targets. Alternative forms of triggering receptor expressed on myeloid cells 2 (TREM2) genes are examples of such risk factors, which contribute higher risk for developing AD. Comprehending TREM2 function pledge to provide salient insight into how neuroinflammation contributes to AD pathology. The dearth of microglial TREM2 shepherd to augmented tau pathology is couple with frequent enhancement of activated neuronal stress kinases. The involvement of TREM2 in the regulation of tau-associated innate immune response of the CNS has clearly demonstrated through these findings. However, whether decrease level of TREM2 assists pathology of tau through changed clearance and pathological escalation of tau or through direct contact between microglia and neuron and any alternative possible mechanisms need to examine. This review briefly summarizes distinct functional roles of TREM2 in AD pathology and highlights the TREM2 gene regulation. We have also addressed the impact of TREM2 on β-amyloid plaques and tau pathology in Alzheimer’s disease.

2021 ◽  
Vol 15 ◽  
Author(s):  
Guimei Zhang ◽  
Zicheng Wang ◽  
Huiling Hu ◽  
Meng Zhao ◽  
Li Sun

Alzheimer’s disease (AD) is one of the most common types of age-related dementia worldwide. In addition to extracellular amyloid plaques and intracellular neurofibrillary tangles, dysregulated microglia also play deleterious roles in the AD pathogenesis. Numerous studies have demonstrated that unbridled microglial activity induces a chronic neuroinflammatory environment, promotes β-amyloid accumulation and tau pathology, and impairs microglia-associated mitophagy. Thus, targeting microglia may pave the way for new therapeutic interventions. This review provides a thorough overview of the pathophysiological role of the microglia in AD and illustrates the potential avenues for microglia-targeted therapies, including microglial modification, immunoreceptors, and anti-inflammatory drugs.


Nutrients ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 3082
Author(s):  
M. Victoria Moreno-Arribas ◽  
Begoña Bartolomé ◽  
José L. Peñalvo ◽  
Patricia Pérez-Matute ◽  
Maria José Motilva

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder leading to the most common form of dementia in elderly people. Modifiable dietary and lifestyle factors could either accelerate or ameliorate the aging process and the risk of developing AD and other age-related morbidities. Emerging evidence also reports a potential link between oral and gut microbiota alterations and AD. Dietary polyphenols, in particular wine polyphenols, are a major diver of oral and gut microbiota composition and function. Consequently, wine polyphenols health effects, mediated as a function of the individual’s oral and gut microbiome are considered one of the recent greatest challenges in the field of neurodegenerative diseases as a promising strategy to prevent or slow down AD progression. This review highlights current knowledge on the link of oral and intestinal microbiome and the interaction between wine polyphenols and microbiota in the context of AD. Furthermore, the extent to which mechanisms bacteria and polyphenols and its microbial metabolites exert their action on communication pathways between the brain and the microbiota, as well as the impact of the molecular mediators to these interactions on AD patients, are described.


2022 ◽  
Vol 12 ◽  
Author(s):  
Junhua Xie ◽  
Lien Van Hoecke ◽  
Roosmarijn E. Vandenbroucke

Alzheimer’s disease (AD) is a devastating age-related neurodegenerative disorder with an alarming increasing prevalence. Except for the recently FDA-approved Aducanumab of which the therapeutic effect is not yet conclusively proven, only symptomatic medication that is effective for some AD patients is available. In order to be able to design more rational and effective treatments, our understanding of the mechanisms behind the pathogenesis and progression of AD urgently needs to be improved. Over the last years, it became increasingly clear that peripheral inflammation is one of the detrimental factors that can contribute to the disease. Here, we discuss the current understanding of how systemic and intestinal (referred to as the gut-brain axis) inflammatory processes may affect brain pathology, with a specific focus on AD. Moreover, we give a comprehensive overview of the different preclinical as well as clinical studies that link peripheral Inflammation to AD initiation and progression. Altogether, this review broadens our understanding of the mechanisms behind AD pathology and may help in the rational design of further research aiming to identify novel therapeutic targets.


2017 ◽  
Vol 28 (8) ◽  
Author(s):  
Yuan Zhang ◽  
Xu Chen ◽  
Yanfang Zhao ◽  
Murugavel Ponnusamy ◽  
Ying Liu

AbstractAlzheimer’s disease (AD) is the most common neurodegenerative disorder leading to dementia in the elderly population. AD is associated with the buildup of β-amyloid and tau, which aggregate into extracellular plaques and neurofibrillary tangles. Although the exact mechanism of pathological process of AD is unclear, the dysfunction of protein degradation mechanisms has been proposed to play an important role in AD. The cellular degradation of abnormal or misfolded proteins consists of three different mechanisms: the ubiquitin proteasomal system (UPS), autophagy-lysosomal pathway (ALP), and interaction of molecular chaperones with UPS or ALP. Any disturbance to these systems causes proteins to accumulate, resulting in pathological process of AD. In this review, we summarize the knowledge of protein degradation pathways in the pathogenesis of AD in light of the current literature. In the future, the regulation UPS or ALP machineries could be the cornerstones of the treatment of AD.


2020 ◽  
Author(s):  
Vincent Pons ◽  
Pascal Lévesque ◽  
Marie-Michèle Plande ◽  
Serge Rivest

Abstract BackgroundAlzheimer’s disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia in the world. Microglia are the innate immune cells of CNS, their proliferation, activation and survival in pathologic and healthy brain have previously been shown to be highly dependent on CSF1R.MethodsHere we investigate the impact of such receptor on AD etiology and microglia. We deleted CSF1R using Cre/Lox system, the knock-out (KO) is restricted to microglia in the APP/PS1 mouse model. We induced the knock-out at 3-month-old, before plaque formation and evaluated both 6 and 8-month-old groups of mice.ResultsOur findings demonstrated that CSF1R KO did not impair microglial survival and proliferation at 6 and 8 months of age in APP cKO compared to their littermate controls groups APPSwe/PS1. We have also shown that cognitive decline is delayed in CSF1R-deleted mice. Ameliorations of AD etiology is associated with a decrease in plaque volume in cortex and hippocampus area. A compensating system seems to take place following the knock-out, since TREM2/β-Catenin and IL-34 expression are significantly increased. Such a compensatory mechanism may promote microglial survival and phagocytosis of Aβ in the brain.ConclusionsOur results provide new insights on the role of CSF1R in microglia and how it interacts with the TREM2/β-Catenin and IL-34 system to clear Aβ and ameliorates the physiopathology of AD.


2022 ◽  
Vol 8 ◽  
Author(s):  
Matthieu Lilamand ◽  
François Mouton-Liger ◽  
Emmanuelle Di Valentin ◽  
Marta Sànchez Ortiz ◽  
Claire Paquet

Alzheimer's disease (AD) is the most frequent age-related neurodegenerative disorder, with no curative treatment available so far. Alongside the brain deposition of β-amyloid peptide and hyperphosphorylated tau, neuroinflammation triggered by the innate immune response in the central nervous system, plays a central role in the pathogenesis of AD. Glucose usually represents the main fuel for the brain. Glucose metabolism has been related to neuroinflammation, but also with AD lesions. Hyperglycemia promotes oxidative stress and neurodegeneration. Insulinoresistance (e.g., in type 2 diabetes) or low IGF-1 levels are associated with increased β-amyloid production. However, in the absence of glucose, the brain may use another fuel: ketone bodies (KB) produced by oxidation of fatty acids. Over the last decade, ketogenic interventions i.e., ketogenic diets (KD) with very low carbohydrate intake or ketogenic supplementation (KS) based on medium-chain triglycerides (MCT) consumption, have been studied in AD animal models, as well as in AD patients. These interventional studies reported interesting clinical improvements in animals and decrease in neuroinflammation, β-amyloid and tau accumulation. In clinical studies, KS and KD were associated with better cognition, but also improved brain metabolism and AD biomarkers. This review summarizes the available evidence regarding KS/KD as therapeutic options for individuals with AD. We also discuss the current issues and potential adverse effects associated with these nutritional interventions. Finally, we propose an overview of ongoing and future registered trials in this promising field.


2021 ◽  
Vol 22 (21) ◽  
pp. 11588
Author(s):  
Yulia K. Komleva ◽  
Ilia V. Potapenko ◽  
Olga L. Lopatina ◽  
Yana V. Gorina ◽  
Anatoly Chernykh ◽  
...  

Background: Alzheimer’s disease (AD) is a devastating neurodegenerative disorder. In recent years, attention of researchers has increasingly been focused on studying the role of brain insulin resistance (BIR) in the AD pathogenesis. Neuroinflammation makes a significant contribution to the BIR due to the activation of NLRP3 inflammasome. This study was devoted to the understanding of the potential therapeutic roles of the NLRP3 inflammasome in neurodegeneration occurring concomitant with BIR and its contribution to the progression of emotional disorders. Methods: To test the impact of innate immune signaling on the changes induced by Aβ1-42 injection, we analyzed animals carrying a genetic deletion of the Nlrp3 gene. Thus, we studied the role of NLRP3 inflammasomes in health and neurodegeneration in maintaining brain insulin signaling using behavioral, electrophysiological approaches, immunohistochemistry, ELISA and real-time PCR. Results: We revealed that NLRP3 inflammasomes are required for insulin-dependent glucose transport in the brain and memory consolidation. Conclusions NLRP3 knockout protects mice against the development of BIR: Taken together, our data reveal the protective role of Nlrp3 deletion in the regulation of fear memory and the development of Aβ-induced insulin resistance, providing a novel target for the clinical treatment of this disorder.


2020 ◽  
Vol 21 (20) ◽  
pp. 7452
Author(s):  
Vidyasagar Naik Bukke ◽  
Moola Archana ◽  
Rosanna Villani ◽  
Antonino Davide Romano ◽  
Agata Wawrzyniak ◽  
...  

Alzheimer’s disease (AD) is an age-related dementia and neurodegenerative disorder, characterized by Aβ and tau protein deposition impairing learning, memory and suppressing synaptic plasticity of neurons. Increasing evidence suggests that there is a link between the glucose and glutamate alterations with age that down-regulates glucose utilization reducing glutamate levels in AD patients. Deviations in brain energy metabolism reinforce the development of AD by hampering glutamate levels in the brain. Glutamate is a nonessential amino acid and the major excitatory neurotransmitter synthesized from glucose. Alterations in cerebral glucose and glutamate levels precede the deposition of Aβ plaques. In the brain, over 40% of neuronal synapses are glutamatergic and disturbances in glutamatergic function have been implicated in pathophysiology of AD. Nevertheless, targeting the glutamatergic system seems to be a promising strategy to develop novel, improved therapeutics for AD. Here, we review data supporting the involvement of the glutamatergic system in AD pathophysiology as well as the efficacy of glutamatergic agents in this neurodegenerative disorder. We also discuss exciting new prospects for the development of improved therapeutics for this devastating disorder.


2020 ◽  
Author(s):  
Vincent Pons ◽  
Pascal Lévesque ◽  
Marie-Michèle Plande ◽  
Serge Rivest

Abstract Background: Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the most common form of dementia in the world. Microglia are the innate immune cells of CNS, their proliferation, activation and survival in pathologic and healthy brain have previously been shown to be highly dependent on CSF1R. Methods: Here we investigate the impact of such receptor on AD etiology and microglia. We deleted CSF1R using Cre/Lox system, the knock-out (KO) is restricted to microglia in the APP/PS1 mouse model. We induced the knock-out at 3-month-old, before plaque formation and evaluated both 6 and 8-month-old groups of mice. Results: Our findings demonstrated that CSF1R KO did not impair microglial survival and proliferation at 6 and 8 months of age in APP cKO compared to their littermate controls groups APPSwe/PS1. We have also shown that cognitive decline is delayed in CSF1R-deleted mice. Ameliorations of AD etiology is associated with a decrease in plaque volume in cortex and hippocampus area. A compensating system seems to take place following the knock-out, since TREM2/β-Catenin and IL-34 expression are significantly increased. Such a compensatory mechanism may promote microglial survival and phagocytosis of Aβ in the brain. Conclusions: Our results provide new insights on the role of CSF1R in microglia and how it interacts with the TREM2/β-Catenin and IL-34 system to clear Aβ and ameliorates the physiopathology of AD.


INTRODUCTION Alzheimer’s disease (AD) is characterized by progressive cognitive loss coupled with age-related functional impairment. Its two major brands are β-amyloid plaques and neurofibrillary tangles. There is strong evidence for a relationship between Metabolic Syndrome (MS) and AD. Both pathologies are quite prevalent and dependent on aging. OBJECTIVE The present study seeks to understand the role of the metabolic syndrome in the pathophysiology of Alzheimer’s disease and to describe preventive and therapeutic interventions. METHODOLOGY The review was made based on the search for scientific articles in the electronic databases PUBMED and Web of Science, using the descriptors “Alzheimer’s Disease”, “Metabolic Syndrome” DISCUSSION MS is a metabolic breakdown with the potential to damage insulin signaling in the brain, causing insulin resistance, inhibiting β-amyloid clearance and its accumulation, which generates neuroinflammation. In addition, it induces a prothrombotic state with ischemic effects, resulting in oxidative stress and neuroinflammation and progressive local brain atrophies. The components of the metabolic syndrome are related to AD, exacerbating neuroinflammation and insulin resistance. Preventive and therapeutic measures aiming at the MS are promising. CONCLUSION From the analyzes developed in this study, different relationships between the components of MS and AD are perceived, the first being possible causes and / or effects of the second. Since insulin resistance plays a major role in the initiation and perpetuation of cognitive impairment in AD. Furthermore, the components of MS associated with AD, when treated with preventive and therapeutic measures, break this association by promoting rebalancing of the metabolism.


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