Is Alzheimer's an immune system disease?
by Sarah Knapton for The Telegraph:
Alzheimer’s disease could be prevented or cured by a new drug which reboots the immune system to stop devastating memory loss, scientists believe.
A new study has shown for the first time that immune cells play a crucial role in the formation of sticky plaques which clump between brain cells, preventing them from functioning correctly.
Usually the body protects the brain from these plaques. But US scientists have found that in Alzheimer’s Disease the immune cells in the brain seem to go haywire, producing a molecule which actually reduces the immune response and consumes an important brain nutrient.
However a drug which blocks that molecule is already being tested in cancer patients, and researchers discovered that it stops the formation of plaques. It raises the prospect that statin-like drugs could be given to the middle-aged to ward off dementia.
Animal tests have already shown that the drug, difluoromethylornithine, (DFMO) stops mice developing Alzheimer’s and improved memory in creatures who already had the disorder."It's surprising, because suppression of the immune system is not what the field has been thinking is happening in Alzheimer’s Disease," said Matthew Kan from Duke University School of Medicine, which carried out the study.“Instead, scientists have previously assumed that the brain releases molecules involved in ramping up the immune system, that supposedly damage the brain."All of this suggests to us that if you can block this process, then you can protect, the mouse, at least, from Alzheimer's disease.”
The brains of people with Alzheimer's show two hallmark signs, ‘plaques’ and ‘tangles’. Plaques are the build-up of sticky proteins called beta amyloid, and tangles are twisted strands of a protein called tau.Researchers found that most immune cells stay the same with the onset of Alzheimer’s, but one type, called microglia start producing a molecule called CD11c which suppress the immune system and eats up the important brain protecting nutrient called arginine.The molecule was found in the highest quantities in regions of the brain involved in memory and where neurons had died."We see this study opening the doors to thinking about Alzheimer's in a completely different way, to break the stalemate of ideas in Alzheimer’s," said Dr Carol Colton, professor of neurology at Duke University.“That the drug worked is a strong indication that we may be on an interesting and worthwhile track for better understanding how the Alzheimer’s pathology is started.“There is the possibility that other agents based on this drug could be developed for safe and effective use to stop the early onset of Alzheimer’s.”Dementia charities said the research was promising but advised maintaining a healthy diet and exercising.“These early findings could open new doors for future treatment development for Alzheimer’s, said Dr Laura Phipps of Alzheimer’s Research UK.“Current research suggests that the best way to maintain a healthy brain throughout life is to ensure a balanced diet, not smoke, keep mentally and physically active and exercise regularly, and to keep blood pressure and cholesterol in check.”Dr James Pickett, Head of Research at Alzheimer’s Society said: “This study in animals joins some of the dots in our incomplete understanding of the processes that cause Alzheimer’s disease, in particular around the role played by the immune system.“Importantly, these new findings reflect earlier observations that arginine is reduced in the brains of people with Alzheimer’s disease.”The research was published in the Journal of Neuroscience.Source: http://bit.ly/1E90ue3