Figure 3.

Interaction of immune cells with synaptogenesis, axonal regrowth and myelin sheath repair. In terms of synaptogenesis, astrocytes are beneficial by secreting agrin, thrombospondins (TSPs)‐1 and ‐2, ephrin‐A1 and ephrin‐A5. Microglia is important in synaptic pruning by engulfing synaptic debris and ensure synapse maturation. Complement system exert their positive effects on synaptic pruning and remodeling, along with increasing synaptic density and axonal sprouting. For axonal sprouting, astrocytes can produce stimulating factors like bone morphologic protein 7 (BMP 7), ephrin‐A1 and ephrin‐A5. Macrophages promote axonal sprouting through IL‐10 and oncomodulin release. M2 microglia and macrophage have been found to promote remyelination and may help to repair white matter injury. Astrocytes may also promote remyelination by expressing CD 59 and ciliary neurotrophic factor (CNTF)