Research hints that disease is caused by toxins, whose spread to the brain could be blocked
Scientists have raised hopes that they may be able to create a vaccine to block the progress of Parkinson’s disease.
They believe new research provides evidence that an abnormal protein may trigger the condition. If the theory is correct, researchers say it might be possible to prime a person’s immune system – using a special vaccine – so it is ready to attack the rogue protein as it passes through the body. In this way, the protein would be prevented from destroying a person’s dopamine-manufacturing cells, where the disease inflicts its greatest damage.
This new vision of Parkinson’s has been arousing excitement among researchers. “It has transformed the way we see Parkinson’s,” said Roger Barker, professor of clinical neurosciences at Cambridge University.
Parkinson’s does not usually affect people until they are over 50. However, researchers have uncovered recent evidence that suggests it may be caused by an event occurring 10 to 20 years before its main symptoms – tremors, rigidity and slowness of movement – manifest themselves.
“If you ask Parkinson’s patients if, in the past, they have experienced loss of sense of smell or suffer from disturbed sleep or have problems with their bowels, very often they reply they have,” said Barker, whose work is backed by the charity Parkinson’s UK, whose Parkinson Awareness week ends on Sunday. “Frequently these patients manifest symptoms several years before it becomes apparent they have the disease. We now believe there is a link.”
Barker and many other researchers say toxins get taken up in the bowels of patients and that over the years these are slowly transported to the central nervous system until they become lodged in some of the cells of the brain. There, they ultimately wreak damage to cells of the mid-brain, where dopamine, a neurotransmitter involved in motor control, is made.However, this raises a key question: what is the nature of the toxin? “There is growing evidence to suggest that it is a normal protein that has become altered in shape and this abnormal version causes other proteins of the same type to change their shape as well,” said Barker. “Such abnormal proteins are known as a prions, and we think one of them is critically involved in the development of Parkinson’s.”
Prions were first proposed to be the causes of fatal brain diseases such as Creutzfeldt-Jakob in the 1980s, and have since been linked to a number of conditions affecting humans and animals. The connection between prion-like proteins and Parkinson’s is of relatively recent origin, however.
“Prions are abnormal versions of a normal protein,” said Barker. “They spread by transforming normal proteins with which they come into contact into abnormal versions.” Again, recent evidence suggests this may occur in the brains of Parkinson’s patients. Several attempts were made to transplant brain cells taken from aborted foetuses into the brains of people with Parkinson’s. These foetal cells should have restored the abilities of these patients to make dopamine, and although they did so in some cases, it also became clear that some transplanted dopamine cells developed the pathology of Parkinson’s. “That suggests an agent in patients’ brains spread to the foetal cells and affected them as well,” said Barker.
As to the identity of the protein transformed in Parkinson’s, the main candidate is alpha-synuclein, which is found in the brain, though its function is unclear. Recent research suggests it could be transformed into an abnormal state and play a key role in development of Parkinson’s. More importantly, it is possible that its operations could be blocked by devising vaccines to interrupt its spread through the body and so protect the brain’s dopamine production.
“It is early days, though at least one company – in Austria – has already begun trials,” says Barker. “We are probably many years from such a vaccine for Parkinson’s, but there is no doubt about the level of excitement in the field today.”
http://www.theguardian.com/society/2015/apr/25/parkinsons-disease-vaccine-research-protein?CMP=share_btn_fb
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