Retinal microglia: Functions and diseases

• Published in: Immunology 2022-07, Vol.166 (3), p.268-286
• Main Authors: Fan, Wei, Huang, Weidi, Chen, Jiayi, Li, Na, Mao, Liming, Hou, Shengping
• Format: Article
• Language: English
• Subjects: Communication; Diseases; Homeostasis; Human tissues; Immune system; Immunosurveillance; Inflammation; Microenvironments; Microglia; microglial function; microglial transdifferentiation; Nervous system; Phagocytosis; Photoreceptors; Retina; Retinal cells; retinal degeneration; retinal disease; retinal microglia; Tissue analysis
• ISSN: 0019-2805; 1365-2567
• DOI: 10.1111/imm.13479

Microglia, the resident immune cells in the retina and nervous system, make irreplaceable contributions to the maintenance of normal homeostasis and immune surveillance of these systems. Recently, great progress has been made in determining the origin, distribution, features and functions of retinal microglia and in identifying their roles in retinal diseases. In the retinal microenvironment, microglia constantly monitor changes in their surroundings and maintain balanced functions by communicating with other retinal cells. When disturbed, activated microglia may kill degenerated neurons and photoreceptors through phagocytosis and exacerbate retinal injury by producing multiple proinflammatory mediators. Numerous animal studies and in situ analyses of human tissue have shown that retinal microglia are involved in multiple retinal diseases. The functions and mechanisms of activated microglia in retinal disorders are gradually being elucidated. Increasing evidence points towards the dual roles of microglia in the retina and they are regulated by many factors. How to inhibit the detrimental effects of microglia and promote beneficial effects are worth studying. This review focuses primarily on the features and functions of microglia and how they participate in retinal diseases based on existing research findings. We also discuss current opinions about microglial transdifferentiation. Microglia play important roles in the central nervous system and retina. This article reviewed current understanding of microglial features and functions in the retina under both physiological and pathological conditions. Meanwhile, we also discussed potential methods to treat retinal diseases by targeting retinal microglia.