Purified Microglia Reveal a Chemical Signature That Fails With Age, and Faster Still in Alzheimer's Mice

By separating microglia, astrocytes and neurons from mouse brains and measuring their metabolites directly, researchers found microglia carry a distinct glutathione and polyamine chemistry that declines with normal aging and collapses further in an Alzheimer's mouse model, with disruption of the pathway followed by more amyloid buildup.

Microglia, the brain's resident immune cells, run on a distinct internal chemistry built around glutathione and polyamine metabolism, one that deteriorates with normal aging and falls further in a mouse model of Alzheimer's disease, according to a study published in Nature Cell Biology on April 30, 2026. The finding comes from a team led by Jie Yu and Fengzhi Li that purified microglia, astrocytes and neurons separately from mouse brain tissue, an approach the authors note has been difficult because it requires large numbers of intact cells for reliable chemical analysis.

Using targeted measurement of more than 70 known metabolites plus untargeted profiling that captured 9,854 metabolite features, the researchers found glutathione, an antioxidant, and polyamines, small molecules involved in cell growth and repair, were specifically enriched in microglia compared with neurons and astrocytes. Levels of these metabolites tracked closely with the activity of chemokine related genes, the signals microglia use to summon help or respond to damage, suggesting the chemistry and the cell's inflammatory behavior are linked.

In mice bred to develop amyloid plaques, a widely used model called 5xFAD, microglial glutathione and polyamine levels fell further than in mice that had simply aged. To probe whether this chemistry does something, rather than just tracking alongside disease, the researchers bred mice lacking Gpx1, an enzyme central to the glutathione cycle. In amyloid prone mice, removing Gpx1 was followed by abnormal microglial shape and heavier amyloid deposition, a result the authors present as evidence the pathway is not merely a bystander.

That knockout, however, removed Gpx1 throughout the whole animal, not only in microglia, so the experiment shows what happens when the pathway is disrupted body wide rather than proving the effect originates in microglia alone. The entire study, including the aging comparison and the Alzheimer's model, was conducted in mice, using genetically engineered animals bred specifically to develop plaques; no human brain tissue or human patients were examined.

The authors describe the work as a groundwork map of what makes microglia chemically distinct, one they say opens the door to asking whether the same glutathione and polyamine decline occurs in the aging human brain, and whether it could ever be measured or supported there. Neither question has been tested.