Table 1.

A variety of markers have been proposed for the various non-resting microglial states. The existence of overlap between markers for different states contradicts the idea of the binary ‘M1/M2’ paradigm. CCL2 (Chemokine Ligand 2); STAT3 (Signal Transducer and Activator of Transcription 3); CSTD (Cathepsin D); LPL (Lipoprotein Lipase); CLEC7a (C-type lectin domain containing 7a); TYROBP (TYRO protein tyrosine-kinase bindin protein).

	‘M1’	‘M2’	Senescent/Dystrophic	DAM	Primed
Cytokines	IL-1β, TNF-ɑ, IFN-γ, IL-6	TGF-β, IL-4, IL-13, IL-4Ra, IL-10	TNF-ɑ, IL-6		IL-1β. CD14
Chemokines	CD11b	CD206	CCL2	CD9, CD11c, CD14, CD44, CD86
Membrane Receptors and Channels	MHC-II, Fc-γ, Kv1.3		MHC-II, Kv1.3	TREM2, AXL, CLEC7a	MHC-II, TLR-1, TLR-2, TLR-4, TLR-7
Transcription Factors and Growth Factors	NF-κB, IRF1, STAT3		NF-κB, VEGF
Enzymes		ARG1	MMP1, SA-β-GAL	CSTD, LPL
Other	ROS, NOS	FIZZ1, Ym1/2	Ferritin, p16INK4a	TYROBP, APOE, CST7	ROS
References	[42,48,49]	[37,39,41,42,50,51]	[52,53,54,55]	[56,57,58,59]	[60,61,62,63]