Stanford Medicine researchers report that blocking a single receptor on a class of long-lived immune cells left multiple organs in aging mice looking more youthful, with the brain among them. The work, done in mice and human cells, centers on tissue-resident macrophages - immune cells that take up permanent residence inside organs rather than circulating through the bloodstream.
The team found that these macrophages lose their ability with age to clear away another class of immune cells, and that this housekeeping failure appears to feed aging across the body. The receptor they disabled normally responds to a hormone tied to inflammation and pain in both mice and humans. When it was switched off specifically in tissue-resident macrophages, youthful characteristics were preserved in the brain, heart, skeletal and cardiac muscle, liver, spleen, bone marrow, kidney and colon.
Mice with the receptor disabled were also protected from several conditions that track with chronic inflammation and aging, including frailty, excess fat accumulation and heart trouble. Cognitive decline was substantially reduced as well, according to Katrin Andreasson, MD, the Edward F. and Irene Thiel Pimley Professor in Neurology and Neurological Sciences at Stanford.
For dementia research, the appeal of a finding like this is its breadth. Rather than targeting a single disease protein in the brain, it suggests that a common inflammatory switch inside resident immune cells may sit upstream of decline in many organs at once - including the cognitive decline that accompanies aging. That remains a hypothesis built on mouse experiments and human cells, not people.