People's brain defenses against invading microorganisms can cause Alzheimer's disease, which shows that vaccines can prevent this condition.
Alzheimer's disease has long been thought to be related to the accumulation of B-amyloid in the sticky plaques in the brain, but the function of these plaques has been unclear. "Do they play a role in the brain, or are they just accumulating like garbage?" Rudolph Tanzi, Harvard Medical School, USA questioned.
Now, Tanzi has discovered that these plaques can act as a defense system against invading pathogens. Tanzi's team and Robert Moir's team at Massachusetts General Hospital in Boston found that B-amyloid can act as an antibacterial compound and form part of the human immune system.
In order to understand whether B-amyloid protein can help humans resist microorganisms that try to enter the brain, the team injected the mouse brain with bacteria that may produce plaque like humans. This can directly form plaques.
"When you look at these plaques, you will find that there is a bacterium in each plaque." Tanzi said, "A bacterium can form a complete plaque overnight."
This shows that infection triggers plaque formation. These sticky plaques may block or kill bacteria, viruses, and other pathogens, but if they are not removed quickly, they may cause inflammation and tangles other proteins, leading to neuronal death, and speeding up Alzheimer’s The progression of the disease.
"So, the stickiness of light powder-like protein has both advantages and disadvantages," said Samuel Gandy of Sinai Hospital in New Zealand.
"This work is very important, it shows that amyloid is associated with infection." said Brian Balin of the Philadelphia College of Osteopathic Medicine, Pennsylvania. His research has shown that Chlamydia pneumoniae is a potential factor that triggers the formation of B-amyloid, and other studies have also shown that sporangia virus can trigger the formation of B-amyloid. But so far, there is no good explanation for why such plaques form and how they accumulate.
The Jacobus Jansen team at Maastricht University in the Netherlands found through MRI brain scans that patients in the early stages of Alzheimer's disease have a more permeable brain blood barrier, which indicates that the disease is due to the fact that the brain is very vulnerable to pathogens. "The microbiological hypothesis seems to be feasible," Jansen said.
If the infectious agent can prevent the formation of plaque, then the vaccine can have an effect on the disease group. "In other words, if people can prevent those pathogens through vaccination, they can prevent subsequent plaque formation." Moir said.