Alzheimer's: Scientists discover 'profound influence' of immune cells on disease progression

A small group of immune cells in the brain could hold the key to slowing down progression of Alzheimer’s disease, scientists believe.

UK researchers have found that microglia, which act the first line of defence against infections in the body’s central nervous system, increase in numbers when they encounter harmful proteins in the brain linked to Alzheimer’s disease.

But instead of protecting the nervous system, this growth causes the microglia to become dysfunctional, meaning they accelerate the build-up of this toxic protein – known as amyloid – instead of trying to get rid of them.

The researchers said their findings, published in the journal Cell Reports, could pave the way for developing new treatments for the disease by focusing on microglia.

“We have previously established that microglia respond to toxic amyloid by proliferating, which is part of their function as immune cells – they are trying to contain a foreign protein," said Dr Diego Gomez-Nicola, of the University of Southampton, who led this research. “However, this is the first time we have seen the long-term consequences of this proliferation on the cells, and the impact for the development of the disease.”

The scientists studied the effects of microglia on mice with Alzheimer’s-like symptoms. The findings were then replicated in samples from deceased patients with the disease.

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They found that by stopping the growth of microglia in the lab rodents, they could slow down the rate at which these cells became dysfunctional. This, in turn, reduced the level of toxic amyloid protein in the brain.

The researchers said their work could have “major implications” for slowing down the progression of Alzheimer’s disease.

“These findings have pinpointed a small group of microglia that have a profound influence on the rate at which Alzheimer’s disease accelerates," said Gomez-Nicola.

“As well as providing scientists with more insight into the starting point of the disease, it will enable future research and drug discovery efforts to be refined to target these senescent cells specifically, and hopefully expedite further breakthroughs in the search for effective treatments.”

There are around 850,000 people with dementia in the UK, which is projected to rise to 1.6 million by 2040.