Genetic targeting or pharmacological inhibition of galectin-3 dampens microglia reactivity and delays retinal degeneration

Dysfunctional humoral and cellular innate immunity are key components in the development and progression of age-related macular degeneration (AMD). Specifically, chronically activated microglia and their disturbed regulatory system contribute to retinal degeneration. Galectin-3, a b-galactose binding protein, is a potent driver of macrophage and microglia activation and has been implicated in neuroinflammation, including neurodegenerative diseases of the brain. Here, we report that galectin-3 is strongly upregulated in reactive retinal microglia of AMD patients and in two related mouse models of retinal degeneration. Specific targeting of galectin-3 by genetic knockout or using the small-molecule inhibitor TD139 blocks microglia reactivity and protects from retinal damage in different models of light-induced retinal degeneration. These data define galectin-3 as potent driver of retinal degeneration and highlight the protein as a drug target for ocular immunomodulatory therapies. Overall design: Global mRNA expression analysis of Balb/cJ mouse retinas in naive and light exposued mice with vehicle or TD139 treatment