Table 1 M2 markers
From: Neuroinflammation and M2 microglia: the good, the bad, and the inflamed
M2 marker | Function | Expressed in murine microglia? | Expressed in human microglia? | Reference |
|---|---|---|---|---|
Arginase 1 (Arg1) | Converts L-arginine into prolines and polyamines implicated in tissue remodeling and wounding healing. It competes with iNOS for substrates. | Yes | Debated: evidence suggests it is not upregulated in human beings but others have shown elevations in the CNS. | |
Ym1 (Chi3l3) | A secretory lectin that binds heparin/heparan sulfate. It is proposed to prevent degradation of extra cellular matrix components. | Yes | Similar to arginase 1 as it has been seen in human beings. However, it might not be expressed in M2 microglia. | |
FIZZ1 (RetnlB) | Mediates interactions between sensory nerves and inflammatory cells in the lungs. It blocks nerve growth factor induced survival of dorsal root ganglion neurons. | Yes | Unknown | |
MRC (CD206) | Binds and internalizes/phagocytoses mannosylated ligands. | No, limited to perivascular macrophages and meninges | Observed in vitro. | |
CD163 | Binds and internalizes hemoglobin-haptoglobin complex. | Yes | Yes | |
TREM2 | The endogenous ligand is unknown, but thought be involved in debris clearance. | Yes | Yes | |
Dectin-1 (Clec7A) | Recognizes β-glucans and can lead to phagocytosis. | Yes | Observed in human macrophages but unknown whether it is expressed in human microglia. | |
CD301 (MGL1) | Recognizes terminal galactose and N-acetylgalactosamine. Involved in pathogen defense and related to CD206. | Yes (our observations) | Unknown | [46] |