12. glial cells v Flashcards
(14 cards)
What are microglia?
Immune cell populations in the brain residing in the brain parenchyma
Microglia are distinct from other macrophage populations found in perivascular spaces, meninges, and choroid plexus.
What factors contribute to microglial diversity?
Microglial diversity includes:
* Morphology
* Regional density
* Turnover rates
* Gene expression
Different brain regions exhibit varying characteristics in these aspects.
How do microglia survey their environment?
Microglia constantly survey their environment using motile processes
Each microglial cell monitors a specific territory in a mosaic-like distribution.
What triggers microglial processes to extend toward a site?
Detection of damage, such as ATP release
This response occurs rapidly and continuously within minutes.
What is synaptic pruning?
Selective removal of synapses during development by microglia
Demonstrated in the visual system through experiments with tracers.
What role do microglia play in synaptic pruning?
Microglia preferentially remove ipsilateral connections in the dorsal lateral geniculate nucleus
This process is mediated by complement receptor 3 on microglia.
How do microglia influence neuronal development?
They influence axonal outgrowth and positioning of specific neuronal populations
Studies with microglia-deficient mice show altered neuronal development.
What happens to excess neural progenitor cells?
They undergo apoptosis and are cleared by microglia
This is particularly important in the dentate gyrus where adult neurogenesis occurs.
What is the current understanding of microglial states in disease?
Microglia exist in various states along a spectrum, not just M1 vs. M2
These states depend on factors like stimuli, age, genetic background, sex, and systemic inflammatory status.
What evidence links microglia to Alzheimer’s disease?
Systemic infections accelerate cognitive decline and risk genes associated with immunity (TREM2, APOE)
Genome-wide association studies have highlighted these relationships.
What are disease-associated microglia (DAMs)?
A subset of microglia (~10-15%) that adopt a specific phenotype around amyloid plaques
This involves a two-step conversion process requiring TREM2.
How do activated microglia contribute to neurodegeneration?
They execute synaptic degeneration and act as transducers of pathology
Initial activation occurs due to amyloid-beta misfolding.
True or False: The role of microglia is limited to being pro-inflammatory (M1) or anti-inflammatory (M2).
False
The understanding of microglial roles has evolved to recognize a spectrum of states.
Fill in the blank: Microglia efficiently clear _______ cells in the dentate gyrus.
apoptotic
This process is crucial to prevent toxicity from excess cells.
