Microglia and other brain immune cells - Vocabulary flashcards

A set of vocabulary-style flashcards covering key microglia concepts from the lecture notes.

Microglia

Brain-resident immune cells that monitor the CNS environment; originate from yolk sac progenitors and self-renew in the brain.

Surveillant microglia

Resting, ramified microglia that continuously patrol the brain parenchyma for signs of trouble.

Synaptic pruning

Microglia-mediated removal of excess or weak synapses during development, often involving complement signaling.

Phagocytosis

Engulfment and digestion of dead cells, debris, or synaptic material by microglia.

Apoptotic cell clearance

Microglia remove dying cells during development and in the adult brain through phagocytosis.

Dendritic cell (brain)

Antigen-presenting cell listed among brain macrophage subpopulations.

Meningeal macrophage

Macrophage population located in the meninges surrounding the CNS.

Perivascular macrophage

Macrophages in the perivascular space around brain blood vessels.

Choroid plexus macrophage

Macrophages in the choroid plexus involved in CSF surveillance.

Monocyte-derived macrophage

Macrophages that originate from circulating monocytes and can infiltrate the CNS during inflammation.

Yolk sac hematopoiesis

Embryonic source of microglial precursors in the yolk sac before CNS colonization.

Fetal liver monocytes

Hematopoietic source contributing to monocyte/macrophage lineage during development.

Self-renewal

Microglia maintain their population in the brain by dividing themselves, with limited input from bone marrow.

Steady-state brain

Normal, non-diseased brain with microglia in a surveillant, homeostatic state.

Inflamed brain

Brain in which microglia adopt activated transcriptional programs and inflammatory functions.

Core transcriptional module

Conserved set of microglial genes defining baseline identity across species.

Environment-dependent transcriptional module

Microglial gene programs that vary with brain environment and include GWAS hits for AD/PD/MS.

DAM (Disease-Associated Microglia)

Microglial transcriptional state enriched in neurodegenerative disease, often TREM2-dependent.

MGnD

Microglia phenotype linked to neurodegeneration; related to DAM in several studies.

TREM2

Microglial receptor promoting transition toward disease-associated/microglial activation states.

P2ry12

Purine receptor marking homeostatic microglia; often downregulated in disease-associated states.

MerTK

Receptor tyrosine kinase important for phagocytosis, including apoptotic cell clearance by microglia.

APOE

Apolipoprotein E; genetic risk factor for Alzheimer's disease; expressed by microglia in disease states.

Spp1 (osteopontin)

Gene upregulated in certain activated microglial states; involved in inflammatory responses.

Lgals3 (galectin-3)

Glycoprotein involved in microglial activation and phagocytosis.

Gpnmb

Gene expressed in microglial activation states, part of the MGnD signature.

Pu.1 (Spi1)

Transcription factor essential for myeloid/microglial lineage commitment.

SALL1

Transcription factor marking homeostatic microglia.

Tmem119

Microglia-specific surface marker used to identify microglia in studies.

CX3CR1

Fractalkine receptor on microglia; mediates neuron-microglia communication and surveillance.

CX3CL1

Fractalkine; neuronal ligand for CX3CR1.

CD200/CD200R

Signaling axis that maintains microglial quiescence and limits activation.

SIRPα/CD47

“Don’t eat me” signals that restrain microglial phagocytosis.

PAMPs

Pathogen-associated molecular patterns that activate microglia via innate receptors.

DAMPs

Damage-associated molecular patterns released by stressed/dying cells to activate microglia.

LPS

Bacterial endotoxin used experimentally to trigger microglial inflammatory responses.

Pro-inflammatory cytokines

Cytokines such as IL-1β, IL-6, and TNF-α produced by activated microglia.

Anti-inflammatory mediators

Cytokines like IL-10 that promote anti-inflammatory responses and tissue protection.

Resting microglia

Microglia in a surveillant, homeostatic state with ramified morphology.

Activated microglia

Microglia that shift to pro- or anti-inflammatory states in response to challenges.

Chronic neurodegenerative diseases

Long-term brain diseases (e.g., Alzheimer’s, Parkinson’s) in which microglia contribute to pathology.

Complement pathway in pruning

System that tags synapses for removal by microglia via receptors like CR3.

CR3

Complement receptor 3 on microglia involved in synaptic pruning; KO reduces engulfment.