The role of Toll like receptors in retinal microglia in retinal inflammatory and ischemic diseases

Toll-like receptors (TLRs) play crucial roles in the innate immune system by recognizing pathogen-associated molecular patterns derived from various microbes and self-derived molecules derived from damaged cells.TLRs can express in multiple cells in the retina, such as glia cells, retinal pigment epithelium (RPE) as well as photoreceptor cells.When combined with special ligands, TLRs can initiate intracellular signal transduction pathways, induce specific gene expression, and upregulate the expression of costimulatory molecules as well as stimulate the secretion of inflammatory factors which take part in resisting to infection.Furthermore, these inflammatory factors may have an effect on retinal neovascular diseases via regulating angiogenic growth factors level.Microglia cells are the most important part in retinal innate immune system as they can participate in immune surveillance and tissue repair.Among the recognition receptors of microglia cells, TLRs play a significant role in regulating microglia cells which involved in retinal infection and inflammation as well as ischemic retinal diseases.In this review, we focused on the role of TLRs in microglia cells.