Innate Immune Pathways Regulating Retinal Cell Development and Regeneration.

Development of the vertebrate retina involves the interaction of multiple signaling pathways and cell types, and there is growing appreciation of the role of innate immune pathways in this process. Resident innate immune cells, particularly microglia, play myriad roles in retinal development, disease, and regeneration. Here we aim to highlight what is known about innate immune cell populations and pathways in retinal cell development and regeneration. Resident innate immune cells are present from the earliest stages of retinal development and regulate developmental cell elimination, synapse refinement, angiogenesis, and recovery from retinal damage. We discuss the signaling pathways mediating immune cell interactions with other cell populations in developing and regenerating retina and highlight species-specific differences in retinal innate immune cell function, which are particularly evident in retinal cell regeneration.