Overview of emerging therapies for demyelinating diseases

Table 1 Summary of different cell types and their function during remyelination and demyelination

Cell type	Role during remyelination		Roles during demyelination
Microglial cell: M2 phenotype	Promotes repair and efficient removal of debris to enhance remyelination by expressing the TREM-2 receptor on the cell surface	Microglial cell: M1 phenotype	Produces pro-inflammatory cytokines, further activating demyelination by recruiting phagocytes to the area as well as generating reactive oxygen species
Oligodendrocyte progenitor cell	Precursor cell type found in the central nervous system that have the potential to differentiate into oligodendrocytes
Oligodendrocyte	Cell type in the central nervous system that produces myelin
Astrocytes	Generate a protein network to localize inflammation and sparing tissue		Can form glial scars, impeding OPC entry. Secretes TNF-α, which further promotes phagocytosis and demyelination

OPC: Oligodendrocyte precursor cell; TNF-α: Tumor necrosis factor-alpha.