American researchers have discovered that immune cells in the brain could, when they are weakened, be the cause of Alzheimer’s disease.
Alzheimer’s disease remains a mystery. Researchers from the University of Washington School of Medicine have just made a important discovery in understanding this pathology. If immune cells in the brain, called microglia, are weakened, tau protein and amyloid plaques develop, which we know causes disease. Stimulating these cells would therefore make it possible to stop, or even prevent the progression of the disease.
The role of Tau protein and amyloid plaques
Before the first symptoms, Alzheimer’s disease is expressed in the brain through the accumulation of amyloid plaques and the transformation of the Tau protein. Gradually, this causes the degeneration of neurons and the loss of cognitive functions characteristic of the disease. For a long time, scientists have wondered about the links between this protein and amyloid plaques.
Weakened cells that create an environment favorable to disease
In this new research, originally published in Nature Neuroscience, the researchers conducted a study on mice. They first started from the observation that a mutation in the TREM2 gene weakens microglia and therefore used it to create several groups of rodents: one part with normal microglia and the other with weakened microglia. Then they injected small amounts of Tau protein into the brains of the mice. Those with weakened microglia had more distorted tau structures near amyloid plaques.
These are present in the brains of many older people and do not always cause Alzheimer’s. But when immune cells in the brain are weakened, the amyloid plaques damage the neurons around them and create an environment conducive to the deformation of Tau structures.
Microglia, cause and cure of the disease
Other tests have shown that immune cells in the brain, when they are functioning normally, isolate these plaques and prevent them from attacking neurons. For the researchers, it would be possible to use microglia to prevent the progression of the disease: when these immune cells are boosted, this could slow down the deformation of the structures of the Tau protein and therefore cognitive losses. Scientists are already working on developing drugs capable of stimulating these cells and preventing the development of the disease.
Today incurable, Alzheimer’s disease results from a slow degeneration of neurons, beginning in the hippocampus (a cerebral structure essential for memory) then spreading to the rest of the brain. It is characterized by disorders of recent memory, executive functions and orientation in time and space. The patient gradually loses his cognitive faculties and his autonomy. 900,000 people are affected in France, according to theInsermfigures constantly increasing.
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