Microglia in Alzheimer's disease
Heela Sarlus1,2, Michael T Heneka1,2,3
1Department of Neurodegenerative Diseases and Gerontopsychiatry, University of Bonn, Bonn, Germany.
Abstract:
Microglia are brain-resident myeloid cells that mediate key functions to support the CNS. Microglia express a wide range of receptors that act as molecular sensors, which recognize exogenous or endogenous CNS insults and initiate an immune response. In addition to their classical immune cell function, microglia act as guardians of the brain by promoting phagocytic clearance and providing trophic support to ensure tissue repair and maintain cerebral homeostasis. Conditions associated with loss of homeostasis or tissue changes induce several dynamic microglial processes, including changes of cellular morphology, surface phenotype, secretory mediators, and proliferative responses (referred to as an "activated state"). Activated microglia represent a common pathological feature of several neurodegenerative diseases, including Alzheimer's disease (AD). Cumulative evidence suggests that microglial inflammatory activity in AD is increased while microglial-mediated clearance mechanisms are compromised. Microglia are perpetually engaged in a mutual interaction with the surrounding environment in CNS; thus, diverse microglial reactions at different disease stages may open new avenues for therapeutic intervention and modification of inflammatory activities. In this Review, the role of microglia in the pathogenesis of AD and the modulation of microglia activity as a therapeutic modality will be discussed.
Insights
Microglia, the brain's immune cells, become overactive and less effective at clearing debris in Alzheimer's disease (AD). Modulating these activated microglia offers a promising therapeutic strategy for AD.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are essential myeloid cells in the central nervous system (CNS), performing immune surveillance and maintaining brain homeostasis.
- They act as sensors, initiating immune responses to insults and supporting tissue repair through phagocytosis and trophic factor release.
- Microglial activation, characterized by morphological and functional changes, is a hallmark of neurodegenerative diseases like Alzheimer's disease (AD).
Purpose of the Study:
- To review the critical role of microglia in the pathogenesis of Alzheimer's disease (AD).
- To explore the therapeutic potential of modulating microglial activity in AD.
Main Methods:
- This review synthesizes current research on microglial function in the CNS.
- It analyzes the dysregulation of microglial inflammatory responses and impaired clearance mechanisms in AD.
- The review discusses the dynamic interactions between microglia and the CNS environment at various disease stages.
Main Results:
- In AD, microglia exhibit heightened inflammatory activity.
- Microglial-mediated clearance functions are significantly compromised in Alzheimer's disease.
- Activated microglia are a common pathological feature across different stages of AD.
Conclusions:
- Microglial dysfunction, including increased inflammation and reduced phagocytosis, contributes significantly to AD pathogenesis.
- Targeting and modulating microglial inflammatory activities present a potential therapeutic avenue for Alzheimer's disease.
- Understanding the diverse microglial reactions in AD may lead to novel treatment strategies.
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