Figure 3.

Glial interactions in retina and optic nerve. In retina, astrocytes, Müller glia, oligodendrocytes, and microglia widely interact to maintain retinal homeostasis by release of trophic factors and cytokines, ATP-exchange, phagocytosis of neuronal debris, antigen presentation, and by promoting activity of each other. Furthermore, retinal glia cells are interactively involved in maintaining retinal vessels as well as blood–retinal barrier, for example, through interactions between microglia and astrocytes. Some glial interactions also impair function of other glial cells. In particular, microglia via release of cytokines (IL-1β and TNF-alpha) affect function of oligodendrocytes, which myelinate axons of retinal ganglion cells in optic nerve. However, microglia can also contribute to oligodendrogenesis. Although glial interactions attempt to maintain retinal homeostasis, they can also promote retinal neurodegeneration. Prodegenerative factors released from glial cells to interact with one another are highlighted in red.