Brain-resident immune cells that have slipped into senescence - a worn-out state in which cells stop dividing but keep signaling to their neighbors - release a protein called DLK1 that disrupts nearby neurons and oligodendrocytes, the cells that protect nerve fibers. The finding comes from a study led by investigators at Weill Cornell Medicine and published August 11 in the journal Neuron.
Working in a mouse model of accelerated aging, the team observed large numbers of these immune cells entering the senescent, dysfunctional state and secreting DLK1. Rather than aging quietly, the cells appear to actively spread trouble to the cells around them. That points to a specific mechanism connecting an aging brain to the memory and thinking problems that often accompany it, and to the heightened vulnerability to neurodegenerative disease that comes with age.
The practical appeal of identifying a secreted protein is that it sits outside the cell, where a drug or antibody could potentially reach it. Study lead author Dr. Li Gan, director of the Helen and Robert Appel Alzheimer's Disease Research Institute at Weill Cornell Medicine, said one strategy the group hopes to test is neutralizing DLK1 in the brain to see whether doing so slows brain aging.
For now this is mouse work, in a model designed to accelerate aging rather than reproduce the slow arc of human aging, and no DLK1-blocking treatment has been tested. What the study contributes is a plausible target and a clearer picture of how senescent immune cells in the brain might drive decline rather than simply accompany it.