New Delhi, Nov 5
A team of scientists has found that the presence of the APOE4 protein -- the most important genetic risk factor for Alzheimer's disease -- can cause healthy immune cells in the brain -- microglia -- to cause harmful inflammation and clumps of misfolded proteins.
The same microglia, in a brain without APOE4 protein, patrol for damage and clear away debris and harmful proteins.
For the study, scientists at Gladstone Institutes in the US created a "chimeric" mice model for studying Alzheimer's. The mouse model not only carries human APOE genes, but the team also transplanted human neurons producing the APOE4 protein into the brains of mice.
On removing microglia, they discovered that the APOE4 protein no longer triggered as many deposits of amyloid or tau -- two types of misfolded proteins that are hallmarks of Alzheimer's disease.
The findings, published in the journal Cell Stem Cell, suggest that drugs that can reduce levels of APOE4 in neurons or target microglia -- either by reducing the number of microglia or their level of inflammatory activity -- could be a promising strategy for slowing or preventing Alzheimer's disease progression in people with the APOE4 gene.
Gladstone Senior Investigator Yadong Huang said that "drugs reducing microglia (in Alzheimer's patients) may eventually be useful in treating the disease".
Importantly, the team transplanted the neurons in the mice model, after the brain matured. This helped the researchers to mimic late-onset Alzheimer's disease.