Changing Functional Signatures of Microglia along the Axis of Brain Aging
Bianca Brawek1, Maryna Skok2, Olga Garaschuk1
1Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, 72076 Tübingen, Germany.
Abstract:
Microglia, the innate immune cells of the brain, are commonly perceived as resident macrophages of the central nervous system (CNS). This definition, however, requires further specification, as under healthy homeostatic conditions, neither morphological nor functional properties of microglia mirror those of classical macrophages. Indeed, microglia adapt exceptionally well to their microenvironment, becoming a legitimate member of the cellular brain architecture. The ramified or surveillant microglia in the young adult brain are characterized by specific morphology (small cell body and long, thin motile processes) and physiology (a unique pattern of Ca2+ signaling, responsiveness to various neurotransmitters and hormones, in addition to classic "immune" stimuli). Their numerous physiological functions far exceed and complement their immune capabilities. As the brain ages, the respective changes in the microglial microenvironment impact the functional properties of microglia, triggering further rounds of adaptation. In this review, we discuss the recent data showing how functional properties of microglia adapt to age-related changes in brain parenchyma in a sex-specific manner, with a specific focus on early changes occurring at middle age as well as some strategies counteracting the aging of microglia.
Insights
Microglia, the brain's immune cells, adapt uniquely to their environment, differing from macrophages. Their functions evolve with aging, influenced by sex, prompting new research into brain health strategies.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are the brain's resident immune cells, part of the innate immune system.
- Under homeostatic conditions, microglia exhibit distinct morphological and functional properties compared to classical macrophages.
- Microglia are integral to brain architecture, possessing diverse physiological functions beyond immunity.
Purpose of the Study:
- To review recent data on microglial functional adaptations to aging.
- To highlight sex-specific changes in microglia during aging.
- To explore strategies for counteracting microglial aging.
Main Methods:
- Review of recent scientific literature and data.
- Analysis of morphological and functional properties of microglia.
- Focus on age-related and sex-specific changes in the brain parenchyma.
Main Results:
- Microglia exhibit unique characteristics in young adult brains, including specific morphology and signaling patterns.
- Aging impacts microglial functional properties through microenvironmental changes.
- These age-related adaptations in microglia show sex-specific patterns.
Conclusions:
- Microglial identity and function are distinct from classical macrophages, adapting dynamically to the brain environment.
- Age-related changes in the brain significantly alter microglial function in a sex-specific manner.
- Understanding these adaptations is crucial for developing strategies to maintain brain health during aging.
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