LOS ANGELES, Aug. 21 (Xinhua) - Scientists from the University of California, Irvine (UC Irvine) have discovered how to forestall Alzheimer's disease in a laboratory setting, a finding that could one day help in devising targeted drugs that prevent it, according to a study published Wednesday in the journal Nature Communications.

The researchers found that by removing brain immune cells known as microglia from rodent models of Alzheimer's disease, beta-amyloid plaques - the hallmark pathology of AD - never formed.

Previous research has shown most Alzheimer's risk genes are turned on in microglia, suggesting these cells play a role in the disease. "However, we hadn't understood exactly what the microglia are doing and whether they are significant in the initial Alzheimer's process," said Kim Green, associate professor of neurobiology and behavior at UC Irvine.

"We decided to examine this issue by looking at what would happen in their absence," Green said.

The researchers used a drug that blocks microglia signaling that is necessary for their survival. Green and his lab have previously shown that blocking this signaling effectively eliminates these immune cells from the brain.

"What was striking about these studies is we found that in areas without microglia, plaques didn't form," Green said. "However, in places where microglia survived, plaques did develop. You don't have Alzheimer's without plaques, and we now know microglia are a necessary component in the development of Alzheimer's."

The scientists also discovered that when plaques are present, microglia perceive them as harmful and attack them. However, the attack also switches off genes in neurons needed for normal brain functioning.

"This finding underlines the crucial role of these brain immune cells in the development and progression of Alzheimer's," said Green, adding that the discovery holds promise for creating future drugs that prevent the disease.