A signaling pathway controlled by transforming growth factor beta (TGF-beta) could be involved in the progression of age-related macular degeneration (AMD), according to a study.1
Researchers at the National Eye Institute (NEI) have found that interrupting TGF-beta signals to immune cells called microglia causes the cells to enter an activated, inflammatory state.1 These activated microglia damage the retina, and the damage is similar to cellular effects observed in AMD, a common cause of vision loss among older Americans.
Scientists have known for years that people with certain variations in genes in the TGF-beta pathway may be more at risk for advanced AMD, which suggests that TGF-beta might contribute to disease progression, according to the NEI.
Under healthy conditions, microglia in the retina integrate a variety of constitutive regulatory signals from other neighboring cells, enabling them to perform homeostatic roles in maintaining retinal structure and function, the authors wrote.
When microglia sense normal levels of these molecules, they adopt a branched shape connected with and maintaining the health of their neuron neighbors. But when the signals change, microglia can enter an activated state, where they move to sites of injury to remove damaged or dead cells.
1. Ma W, Silverman S, et al. “Pathological transformation of retinal microglia in the absence of constitutive TGF-beta signaling induces retinal degeneration and exacerbates choroidal neovascularization.” Jan. 22, 2019. ELife. doi: 10.7554/eLife.42049