scholarly journals Mitochondrial Regulation of Microglial Immunometabolism in Alzheimer’s Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Lauren H. Fairley ◽  
Jia Hui Wong ◽  
Anna M. Barron
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Innate Immunity ◽  
Energy Demand ◽  
High Energy ◽  
Metabolic Programming ◽  
Causative Role ◽  
Immune Functions ◽  
Diverse Range ◽  
Effector Cells

Alzheimer’s disease (AD) is an age-associated terminal neurodegenerative disease with no effective treatments. Dysfunction of innate immunity is implicated in the pathogenesis of AD, with genetic studies supporting a causative role in the disease. Microglia, the effector cells of innate immunity in the brain, are highly plastic and perform a diverse range of specialist functions in AD, including phagocytosing and removing toxic aggregates of beta amyloid and tau that drive neurodegeneration. These immune functions require high energy demand, which is regulated by mitochondria. Reflecting this, microglia have been shown to be highly metabolically flexible, reprogramming their mitochondrial function upon inflammatory activation to meet their energy demands. However, AD-associated genetic risk factors and pathology impair microglial metabolic programming, and metabolic derailment has been shown to cause innate immune dysfunction in AD. These findings suggest that immunity and metabolic function are intricately linked processes, and targeting microglial metabolism offers a window of opportunity for therapeutic treatment of AD. Here, we review evidence for the role of metabolic programming in inflammatory functions in AD, and discuss mitochondrial-targeted immunotherapeutics for treatment of the disease.

scholarly journals A clinical dose of angiotensin-converting enzyme (ACE) inhibitor and heterozygous ACE deletion exacerbate Alzheimer's disease pathology in mice

2019 ◽  
Vol 294 (25) ◽  
pp. 9760-9770 ◽  
Author(s):  
Shuyu Liu ◽  
Fujiko Ando ◽  
Yu Fujita ◽  
Junjun Liu ◽  
Tomoji Maeda ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Angiotensin Converting Enzyme ◽  
Amyloid Precursor Protein ◽  
Ace Inhibitors ◽  
Ace Inhibitor ◽  
Precursor Protein ◽  
Causative Role ◽  
Converting Enzyme ◽  
Clinical Dose

Inhibition of angiotensin-converting enzyme (ACE) is a strategy used worldwide for managing hypertension. In addition to converting angiotensin I to angiotensin II, ACE also converts neurotoxic β-amyloid protein 42 (Aβ42) to Aβ40. Because of its neurotoxicity, Aβ42 is believed to play a causative role in the development of Alzheimer's disease (AD), whereas Aβ40 has neuroprotective effects against Aβ42 aggregation and also against metal-induced oxidative damage. Whether ACE inhibition enhances Aβ42 aggregation or impairs human cognitive ability are very important issues for preventing AD onset and for optimal hypertension management. In an 8-year longitudinal study, we found here that the mean intelligence quotient of male, but not female, hypertensive patients taking ACE inhibitors declined more rapidly than that of others taking no ACE inhibitors. Moreover, the sera of all AD patients exhibited a decrease in Aβ42-to-Aβ40–converting activity compared with sera from age-matched healthy individuals. Using human amyloid precursor protein transgenic mice, we found that a clinical dose of an ACE inhibitor was sufficient to increase brain amyloid deposition. We also generated human amyloid precursor protein/ACE+/− mice and found that a decrease in ACE levels promoted Aβ42 deposition and increased the number of apoptotic neurons. These results suggest that inhibition of ACE activity is a risk factor for impaired human cognition and for triggering AD onset.

The Role of Microglia in Sporadic Alzheimer’s Disease

2021 ◽  
Vol 79 (3) ◽  
pp. 961-968
Author(s):  
Wolfgang J. Streit ◽  
Habibeh Khoshbouei ◽  
Ingo Bechmann
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Late Onset ◽  
Genetic Mutations ◽  
Sporadic Alzheimer’S Disease ◽  
Immune Effector ◽  
Effector Cells ◽  
Immune Effector Cells ◽  
Amyloid Cascade

Microglia constitute the brain’s immune system and their involvement in Alzheimer’s disease has been discussed. Commonly, and in line with the amyloid/neuroinflammation cascade hypothesis, microglia have been portrayed as potentially dangerous immune effector cells thought to be overactivated by amyloid and producing neurotoxic inflammatory mediators that lead to neurofibrillary degeneration. We disagree with this theory and offer as an alternative the microglial dysfunction theory stating that microglia become impaired in their normally neuroprotective roles because of aging, i.e., they become senescent and aging neurons degenerate because they lack the needed microglial support for their survival. Thus, while the amyloid cascade theory relies primarily on genetic data, the dysfunction theory incorporates aging as a critical etiological factor. Aging is the greatest risk factor for the sporadic (late-onset) and most common form of Alzheimer’s disease, where fully penetrant genetic mutations are absent. In this review, we lay out and discuss the human evidence that supports senescent microglial dysfunction and conflicts with the amyloid/neuroinflammation idea.

scholarly journals The Role of the Innate Immune System in Alzheimer’s Disease and Frontotemporal Lobar Degeneration: An Eye on Microglia

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Elisa Ridolfi ◽  
Cinzia Barone ◽  
Elio Scarpini ◽  
Daniela Galimberti
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Frontotemporal Lobar Degeneration ◽  
Environmental Changes ◽  
Current Evidence ◽  
Neuronal Function ◽  
Immune Effector ◽  
Effector Cells ◽  
The Central Nervous System

In the last few years, genetic and biomolecular mechanisms at the basis of Alzheimer’s disease (AD) and frontotemporal lobar degeneration (FTLD) have been unraveled. A key role is played by microglia, which represent the immune effector cells in the central nervous system (CNS). They are extremely sensitive to the environmental changes in the brain and are activated in response to several pathologic events within the CNS, including altered neuronal function, infection, injury, and inflammation. While short-term microglial activity has generally a neuroprotective role, chronic activation has been implicated in the pathogenesis of neurodegenerative disorders, including AD and FTLD. In this framework, the purpose of this review is to give an overview of clinical features, genetics, and novel discoveries on biomolecular pathogenic mechanisms at the basis of these two neurodegenerative diseases and to outline current evidence regarding the role played by activated microglia in their pathogenesis.

scholarly journals Photobiomodulation for Alzheimer’s Disease: Has the Light Dawned?

Photonics ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 77 ◽  
Author(s):  
Michael Hamblin
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Trials ◽  
Near Infrared ◽  
Infrared Light ◽  
Western World ◽  
Diverse Range ◽  
Non Invasive ◽  
Dementia Patients ◽  
Relieve Pain

Next to cancer, Alzheimer’s disease (AD) and dementia is probably the most worrying health problem facing the Western world today. A large number of clinical trials have failed to show any benefit of the tested drugs in stabilizing or reversing the steady decline in cognitive function that is suffered by dementia patients. Although the pathological features of AD consisting of beta-amyloid plaques and tau tangles are well established, considerable debate exists concerning the genetic or lifestyle factors that predispose individuals to developing dementia. Photobiomodulation (PBM) describes the therapeutic use of red or near-infrared light to stimulate healing, relieve pain and inflammation, and prevent tissue from dying. In recent years PBM has been applied for a diverse range of brain disorders, frequently applied in a non-invasive manner by shining light on the head (transcranial PBM). The present review discusses the mechanisms of action of tPBM in the brain, and summarizes studies that have used tPBM to treat animal models of AD. The results of a limited number of clinical trials that have used tPBM to treat patients with AD and dementia are discussed.

F4-06-03: INSIGHTS FROM NEUROPATHOLOGY AND MODULATION OF INNATE IMMUNITY AS A THERAPEUTIC APPROACH FOR ALZHEIMER'S DISEASE

2006 ◽  
Vol 14 (7S_Part_26) ◽  
pp. P1391-P1392
Author(s):  
Eleanor Drummond ◽  
Fernando Goni ◽  
Frances Prelli ◽  
Henrieta Scholtzova ◽  
Thomas Wisniewski
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Innate Immunity ◽  
Therapeutic Approach

Alterations in immune functions during normal aging and Alzheimer's disease

1999 ◽  
Vol 85 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Cai Song ◽  
Maurits Vandewoude ◽  
Wim Stevens ◽  
Luc De Clerck ◽  
Marc Van der Planken ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Normal Aging ◽  
Immune Functions

Recent progress on the role of GABAergic neurotransmission in the pathogenesis of Alzheimer’s disease

2016 ◽  
Vol 27 (4) ◽  
pp. 449-455 ◽  
Author(s):  
Ghulam Abbas ◽  
Wajahat Mahmood ◽  
Nurul Kabir
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Gaba Receptor ◽  
Amyloid Β ◽  
Receptor Subtypes ◽  
Causative Role ◽  
Gabaergic Neurotransmission ◽  
Promising Target ◽  
The Brain

AbstractDespite their possible causative role, targeting amyloidosis, tau phosphorylation, acetylcholine esterase, glutamate, oxidative stress and mitochondrial metabolism have not yet led to the development of drugs to cure Alzheimer’s disease (AD). Recent preclinical and clinical reports exhibit a surge in interest in the role of GABAergic neurotransmission in the pathogenesis of AD. The interaction among GABAergic signaling, amyloid-β and acetylcholine is shown to affect the homeostasis between excitation (glutamate) and inhibition (GABA) in the brain. As a consequence, over-excitation leads to neurodegeneration (excitotoxicity) and impairment in the higher level functions. Previously, the glutamate arm of this balance received the most attention. Recent literature suggests that over-excitation is primarily mediated by dysfunctional GABA signaling and can possibly be restored by rectifying anomalous metabolism observed in the GABAergic neurons during AD. Additionally, neurogenesis and synaptogenesis have also been linked with GABAergic signaling. This association may provide a basis for the needed repair mechanism. Furthermore, several preclinical interventional studies revealed that targeting various GABA receptor subtypes holds potential in overcoming the memory deficits associated with AD. In conclusion, the recent scientific literature suggests that GABAergic signaling presents itself as a promising target for anti-AD drug development.

Paroxysmal slow cortical activity in Alzheimer’s disease and epilepsy is associated with blood-brain barrier dysfunction

2019 ◽  
Vol 11 (521) ◽  
pp. eaaw8954 ◽  
Author(s):  
Dan Z. Milikovsky ◽  
Jonathan Ofer ◽  
Vladimir V. Senatorov ◽  
Aaron R. Friedman ◽  
Ofer Prager ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Causative Role ◽  
Barrier Dysfunction ◽  
Therapeutic Implications ◽  
Young Rats ◽  
Blood Brain ◽  
Nonconvulsive Seizures

A growing body of evidence shows that epileptic activity is frequent but often undiagnosed in patients with Alzheimer’s disease (AD) and has major therapeutic implications. Here, we analyzed electroencephalogram (EEG) data from patients with AD and found an EEG signature of transient slowing of the cortical network that we termed paroxysmal slow wave events (PSWEs). The occurrence per minute of the PSWEs was correlated with level of cognitive impairment. Interictal (between seizures) PSWEs were also found in patients with epilepsy, localized to cortical regions displaying blood-brain barrier (BBB) dysfunction, and in three rodent models with BBB pathology: aged mice, young 5x familial AD model, and status epilepticus–induced epilepsy in young rats. To investigate the potential causative role of BBB dysfunction in network modifications underlying PSWEs, we infused the serum protein albumin directly into the cerebral ventricles of naïve young rats. Infusion of albumin, but not artificial cerebrospinal fluid control, resulted in high incidence of PSWEs. Our results identify PSWEs as an EEG manifestation of nonconvulsive seizures in patients with AD and suggest BBB pathology as an underlying mechanism and as a promising therapeutic target.

scholarly journals The Alzheimer’s disease-associated protective Plcγ2-P522R variant promotes immune functions

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Mari Takalo ◽  
Rebekka Wittrahm ◽  
Benedikt Wefers ◽  
Samira Parhizkar ◽  
Kimmo Jokivarsi ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Immune Cell ◽  
Therapeutic Option ◽  
Immune Functions ◽  
Disease Etiology ◽  
Cell Functions ◽  
Bv2 Microglia ◽  
Brain Mrna ◽  
Protective Variant

Abstract Background Microglia-specific genetic variants are enriched in several neurodegenerative diseases, including Alzheimer’s disease (AD), implicating a central role for alterations of the innate immune system in the disease etiology. A rare coding variant in the PLCG2 gene (rs72824905, p.P522R) expressed in myeloid lineage cells was recently identified and shown to reduce the risk for AD. Methods To assess the role of the protective variant in the context of immune cell functions, we generated a Plcγ2-P522R knock-in (KI) mouse model using CRISPR/Cas9 gene editing. Results Functional analyses of macrophages derived from homozygous KI mice and wild type (WT) littermates revealed that the P522R variant potentiates the primary function of Plcγ2 as a Pip2-metabolizing enzyme. This was associated with improved survival and increased acute inflammatory response of the KI macrophages. Enhanced phagocytosis was observed in mouse BV2 microglia-like cells overexpressing human PLCγ2-P522R, but not in PLCγ2-WT expressing cells. Immunohistochemical analyses did not reveal changes in the number or morphology of microglia in the cortex of Plcγ2-P522R KI mice. However, the brain mRNA signature together with microglia-related PET imaging suggested enhanced microglial functions in Plcγ2-P522R KI mice. Conclusion The AD-associated protective Plcγ2-P522R variant promotes protective functions associated with TREM2 signaling. Our findings provide further support for the idea that pharmacological modulation of microglia via TREM2-PLCγ2 pathway-dependent stimulation may be a novel therapeutic option for the treatment of AD.

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