SPP1 and Hyperglycemia: Conversely, cell-to-cell communication between microglia and other retinal cells is a potential feedback mechanism to restrain exacerbated microglial inflammatory responses under hyperglycemia, including microglial interactions with Müller cells (through osteopontin), amacrine cells (mediated by growth arrest-specific protein 6) and cone photoreceptors (through transforming growth factor-β2) [257].