Microglia

Question 1

Microglia general function?

Answer 1

Resident mononuclear phagocytes of CNS

Question 2

Microglia found more in white or grey matter?

Answer 2

Grey matter

Question 3

Microglia function (3 categories)?

Answer 3

• Surveillance
• Immune response
• Neuroprotective

Question 4

Actions of microglia?

Answer 4

Phagocytose cellular debris, synaptic pruning, trophic support for neurons, immune function

Question 5

Other CNS macrophages?

Answer 5

Ramified microglia, perivascular macrophage, choroid plexus macrophage

Question 6

Neurodevelopment of microglia?

Answer 6

Mesodermal origin -> amoeboid-like cells (1st trimester) -> intermediate profile (2nd) -> ramified morphology (3rd)

Question 7

Where are microglia derived from?

Answer 7

Haematopoietic stem cell (from yolk sac):

HSC -> common myeloid progenitor -> microglia

Question 8

By what signalling do microglia perform synaptic pruning?

Answer 8

C3-CR3 signalling

Question 9

By what signalling do microglia promote the maturation of synapses?

Answer 9

CX3CL1/CX3CR1

Question 10

Describe the 3 stages of microgliosis

Answer 10

Resting: highly ramified
Reactive: shorter processes, enlarged soma
Phagocyte: amoeboid, rounded

Question 11

What happens upon microglial activation?

Answer 11

• Increased migration
• cell proliferation
• phagocytosis
• increased MHC expression
• increased immune cell surface receptors

Question 12

Microglia release ___ to protect neurons and promote regeneration

Answer 12

TGF-b

Question 13

Microglial relationship with neurodegenerative disease?

Answer 13

All neurodegenerative diseases have microglial activation

Question 14

What is the source of new microglia in a PATHOLOGICAL brain?

Answer 14

Division of endogenous in situ microglia (EXCEPTIONS include stroke and MS)

Question 15

Microglia relationship w/ Alzherimer’s disease?

Answer 15

Microglia surround extracellular Amyloid plaques

Question 16

Microglia relationship w/ MS?

Answer 16

Graded activation: closer to lesion means a greater activation (all microglia in the grey matter are activated)

Question 17

Roles of M1 and M2 microglia?

Answer 17

M1: inflammatory, cytotoxic

M2: anti-inflammatory, repair, clearance

Question 18

Roles of A1 and A2 astrocytes?

Answer 18

A1: neurotoxic
A2: reparative

Question 19

Astrocytes and microglia in MS?

Answer 19

THEORY
Activated microglia -> TNF -> induce A1

OR

Microglia start as M1 (to remove pathogen) and change to M2 (reduce inflamm + stimulate repair)