Would a more vigorous immune system help prevent Alzheimer's disease? The immune system looks like it protects our brains from beta-amyloid build-up. So would immune system rejuvenation protect the brain from Alzheimer's?
Recent work in mice suggested that the immune system is involved in removing beta-amyloid, the main Alzheimer's-causing substance in the brain. Researchers have now shown for the first time that this may apply in humans.
Researchers at the Peninsula College of Medicine and Dentistry, University of Exeter with colleagues in the National Institute on Aging in the USA and in Italy screened the expression levels of thousands of genes in blood samples from nearly 700 people. The telltale marker of immune system activity against beta-amyloid, a gene called CCR2, emerged as the top marker associated with memory in people.
The immune system ages along with the rest of the body. Is Alzheimer's disease partly caused by the immune system becoming too sluggish to prevent beta-amyloid build-up in the brain?
A rejuvenated immune system would offer a number of advantages. Most obviously, old people would be at less risk of death from pneumonia or assorted infections picked up in hospitals. But also, an aged immune system is associated with an increased risk of cancer. In fact, rare people have an especially anti-cancer immune system. So a combined rejuvenation and anti-cancer enhancement of the immune system would cut cancer risks.
Since the immune system also removes metabolic trash from the body a rejuvenated immune system would likely reduce the rate of overall body aging by preventing the build-up harmful secretions of cells such as beta-amyloid.
Researchers at the Karolinska Institutet in Sweden have developed a vaccine against beta amyloid protein which might enable the immune system to basically gobble up this protein that causes death of neurons and their support cells.
The new treatment, which is presented in Lancet Neurology, involves active immunisation, using a type of vaccine designed to trigger the body's immune defence against beta-amyloid. In this second clinical trial on humans, the vaccine was modified to affect only the harmful beta-amyloid. The researchers found that 80 per cent of the patients involved in the trials developed their own protective antibodies against beta-amyloid without suffering any side-effects over the three years of the study. The researchers believe that this suggests that the CAD106 vaccine is a tolerable treatment for patients with mild to moderate Alzheimer's. Larger trials must now be conducted to confirm the CAD106 vaccine's efficacy.
One problem I see: the immune systems of older folks are much less effective due to aging. Will the aged be able to mount a big enough immune response to clear away the beta amyloid? Not clear.