Immune cells may play a greater role in Alzheimer’s disease than we thought
Neurobiologists from University of California, Irvine with the Sue & Bill Gross Stem Cell Research Center and the Institute for Memory Impairments and Neurological Disorders have discovered that the body’s immune system, which helps fight off bacteria, may play a larger role in Alzheimer’s disease.
The researchers observed this when they genetically modified Alzheimer’s disease mice to lack key immune cells – T-cells, B-cells, and NK-cells – in their blood. The accumulation of the distinctive brain plaques that were associated with the neurodegenerative disorder increased twofold in these mice.
Alzheimer’s disease is the number one cause of age-related dementia. It is thought to be caused by the accumulation of a protein called beta-amyloid which then amasses to form the amyloid plaques.
Matthew Blurton-Jones, an assistant professor of neurobiology and behavior, along with Samuel Marsh, a doctoral student, wanted to test if immune cells that reside outside the brain and play a huge role in autoimmune diseases might also affect Alzheimer’s in some way. So, they genetically modified mice with Alzheimer’s to lack three certain immune cells. After six months, the brains of these mice showed more than double increase rate of the accumulation of the beta-amyloid protein.
To confirm their findings, they transplanted healthy bone marrow stem cells to the genetically-modified mice to help them develop new immune cells. This transplantation allowed the B-cells to create new antibodies that reached the brain and helped eradicate the beta-amyloid.
“We found that in Alzheimer’s mice with intact immune systems, antibodies — which are made by B-cells — accumulated in the brain and associated with microglia. This, in turn, helped increase the clearance of beta-amyloid,” according to Marsh.
“We know that the immune system changes with age and becomes less capable of making T- and B-cells. So whether aging of the immune system in humans might contribute to the development of Alzheimer’s is the next big question we want to ask,” Blurton-Jones added.
Source: Science Daily.
