Study Reveals Brain Immune Cells Could Help Prevent Alzheimer’s Disease

Research indicates that certain immune cells in the brain may be essential in delaying the onset of Alzheimer’s disease. This finding could pave the way for new treatments designed to encourage these cells into a protective state.

Previous studies have shown that a type of brain immune cell, known as microglia, can both alleviate and exacerbate Alzheimer’s symptoms due to their role in inflammation. An international team of scientists has explored how microglia toggle between these helpful and harmful roles.

In experiments with Alzheimer’s mouse models, Pinar Ayata and her colleagues at the Icahn School of Medicine discovered that when microglia come into contact with amyloid-beta protein clumps—common indicators of Alzheimer’s—they enter a unique neuroprotective state.

“Microglia are not just harmful responders in Alzheimer’s; they can actually protect the brain,” says neuroscientist Anne Schaefer from the Icahn School of Medicine in New York. She adds that their findings enhance understanding of microglia’s remarkable adaptability and their vital roles in various brain functions.

Interestingly, the study identified two key traits of this protective microglia subtype: they exhibit lower levels of a protein linked to Alzheimer’s called PU.1, while showing increased expression of another protein known as CD28, which plays a critical role in the immune system.

This specific combination of characteristics allowed microglia to effectively slow the accumulation of amyloid-beta proteins in mice and also limit the buildup of tau, another protein connected to Alzheimer’s. When researchers decreased CD28 levels in the mice, they noticed a surge in inflammatory microglia and a rise in amyloid-beta plaques.

This aligns with earlier research indicating that individuals with a genetic predisposition for lower PU.1 levels tend to develop Alzheimer’s later in life. “These findings explain why reduced PU.1 levels are associated with a lower risk of Alzheimer’s,” notes geneticist Alison Goate from the Icahn School of Medicine.

While it seems to be a natural mechanism against Alzheimer’s progression, it’s clear it isn’t strong enough to halt the disease entirely. The researchers are optimistic that future therapies could enhance this subtype of microglia, though verifying their function in humans is essential first.

Alzheimer’s is a notably complex condition influenced by various risk factors, which suggests that effective treatments will likely need to target multiple aspects simultaneously. One potential avenue for future research could involve triggering microglia to adopt this neuroprotective state.

The research also sheds light on how Alzheimer’s interacts with the immune system at large. The modified microglia found in this study appear to function similarly to T cells, the immune cells patrolling other parts of the nervous system.