EVIDENCE that Parkinson鈥檚 disease may be an autoimmune disorder could lead to new ways to treat the illness.
Parkinson鈥檚 begins with abnormal clumping of a protein called synuclein in the brain. Neighbouring dopamine-producing neurons then die, causing tremors and difficulty moving.
The prevailing wisdom has been that these neurons die from a toxic reaction to synuclein deposits. However, Parkinson鈥檚 has been linked to some gene variants that affect how the immune system works, leading to an alternative theory that synuclein causes Parkinson鈥檚 by triggering the immune system to attack the brain.
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An argument against this theory has been that brain cells are safe from immune system attack, because most neurons don鈥檛 have antigens 鈥� the markers immune cells use to recognise a target. But by studying postmortem brain tissue samples, at Columbia University and his team have discovered that dopamine-producing neurons do display antigens. The team has now conducted blood tests to reveal that people with Parkinson鈥檚 show an immune response to these antigens, while people who don鈥檛 have the condition do not (Nature, DOI: ).
These findings suggest Parkinson鈥檚 may be an autoimmune disorder, in which the immune system mistakenly attacks part of the body. There have been hints before that the immune system is involved in Parkinson鈥檚, but this is the first evidence that it plays a major pathological role, says at the University of Cambridge. 鈥淚t would be an attractive target for therapeutic intervention,鈥� he says.
However, it isn鈥檛 clear yet if the immune response directly causes neuron death, or if it is merely a side effect of the disease. Sulzer鈥檚 team plans to try blocking the autoimmune response in Parkinson鈥檚, to see if this can stop the disease progressing.
This article appeared in print under the headline 鈥淧arkinson鈥檚 may be the result of immune attack鈥�
