BREAKTHROUGH: Brain ‘cleaning’ revelation could combat Alzheimer’s and Parkinson's disease

By OLIVIA LERCHE PUBLISHED
 May 26, 2016

A DISCOVERY which has revealed how the brain cleans itself of toxins could lead to treatment for dementia, Alzheimer’s and Parkinson’s disease.  

The findings could lead to new treatments for Alzheimer's disease

Scientists have found that when neurons - specialised cells which transmitting nerve impulses - die, the debris needs to be removed for the brain tissue to continue functioning properly.

The process of brain cleaning - which gets rid of the dead material - is called phagocytosis, and is carried out by highly specialised cells in the brain called microglia.

A new study has, for the first time, investigated the process of neuronal death and microglial phagocytosis in the diseased brain of epilepsy patients and mice.

It is known that during epilepsy-associated seizures, neurons die. However, contrary to what happens in the healthy brain, during epilepsy, microglia seem to be ‘blind’ and unable to find the dead neurons and to destroy them.

Experts say the behaviour of the microglia is ‘abnormal’ and dead neurons cannot be eliminated.

This means the dead neurons accumulate, spreading the damage to neighbouring neurons and triggering an inflammatory response that worsens the brain injury.

Lead author Dr Amanda Sierra, director of the Laboratory of Glial Cell Biology at the Achucarro Basque Centre for Neuroscience said: "Phagocytosis, the engulfment and digestion of cellular debris, is at the core of the regenerative response of the damaged tissue, because it prevents the spillover of toxic intracellular contents and is actively anti-inflammatory.

"In the brain, the professional phagocytes are microglia, whose dynamic processes rapidly engulf and degrade cells undergoing apoptosis - programmed cell death - in physiological conditions.

The scientists believe the findings could lead to new treatments to alleviate the effects of brain diseases not only for epilepsy but Alzheimer's disease, Parkinson’s disease and stroke, which are all neurdegenerative conditions and affect thousands of people across the UK. 

"Thus, microglia hold the key to brain regeneration, but their efficiency as phagocytes in the diseased brain is only presumed,” added Dr Sierra. 

"Our data strongly support that this inflammation may at least in part originate from the microglial phagocytic impairment, but whether this dysfunction contributes to seizures remains to be determined.

Microglia are not just 'reactive' to damage but function impaired

In summary, our results demonstrate that in the epileptic brain, microglia are not merely 'reactive' to the neuronal damage but have their basal phagocytic function impaired.

"Because neuronal death and inflammation are hallmarks of all major brain diseases, such as ischemic stroke, Alzheimer, Parkinson, or multiple sclerosis, harnessing microglial phagocytosis may serve to control tissue damage and inflammation as a novel strategy to accelerate brain recovery."

Some 850,000 people in the UK have Alzheimer’s, a figure which could hit two million within 30 years.

The study was published in PLOS Biology.

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