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Parkinson's partially an autoimmune disease?


Autoimmune response plays an important role in Parkinson's disease
Parkinson's is a neurodegenerative disease that is common around the world. Researchers have now found the first direct evidence that so-called autoimmunity plays an important role in Parkinson's disease.

Scientists at Columbia University Medical Center (CUMC) found that autoimmunity has a strong impact on Parkinson's disease. If the immune system attacks the body's own tissue, this can have a significant impact on the development of Parkinson's. The doctors published the results of their study in the journal "Nature"

Alpha-synuclein can activate T cells
The current study results show a way to prevent the death of neurons in Parkinson's disease by a therapy that dampens the immune response, the experts say. The idea that a faulty immune system contributes to Parkinson's is almost 100 years old, explains author Professor David Sulzer. So far, however, no one has been able to prove a connection. Our results show that two fragments of alpha-synuclein, a protein that accumulates in the brain cells of people with Parkinson's, can activate T cells, the scientists explain. These cells are involved in so-called autoimmune attacks.

Identify people at increased risk
It remains to be seen whether the immune response to alpha-synuclein is an initial cause of Parkinson's or whether it contributes to neuronal death and thus worsens the symptoms after the onset of the disease, explains the author Professor Alessandro Sette. However, the current results could contribute to the development of a much-needed diagnostic test for Parkinson's disease, thus helping to identify people at higher risk or those affected in the early stages of the disease, the researchers explain.

T cells can view neurons damaged by Alzheimer's as invaders
A 2014 study made it clear that dopamine neurons (affected by Parkinson's disease) are particularly vulnerable because they have proteins on the cell surface that help the immune system recognize foreign substances, the researchers explain. In other words: T cells can view neurons as foreign invaders if they have been damaged by Parkinson's disease.

Doctors examined over 100 subjects for their study
In their study, the researchers examined the blood samples from 67 Parkinson's patients and 36 age-matched healthy volunteers. They searched for fragments of alpha-synuclein and other proteins that can be found in neurons. They analyzed participants' samples to find out which protein fragments triggered an immune response.

What causes autoimmune response in Parkinson's?
The identified immune response was associated with the common form of a particular gene. This could explain why many people with Parkinson's disease carry such a gene variant, the scientists emphasize. The autoimmune response in Parkinson's disease arises when neurons are no longer able to break down the abnormal alpha-synuclein, the researchers suspect.

The recycling process of the proteins is reduced by Parkinson's
The damaged proteins are usually broken down and recycled. However, this recycling process decreases with age and through certain diseases - including Parkinson's, explains Professor Sulzer in a press release from the Columbia University Medical Center.

More research is needed
If the abnormal alpha-synuclein begins to accumulate, the immune system could mistake the protein for pathogens. This then leads to an attack by the immune system, the doctors explain. Additional research is now intended to investigate the immune response in other patients and identify the molecular steps that lead to an autoimmune response in animal and cell models.

Immunotherapy could increase immune system tolerance to alpha-synuclein
The new findings open up the possibility of using an immunotherapy approach to increase the tolerance of the immune system to alpha-synuclein. This could help slow the worsening of symptoms in Parkinson's patients, adds Professor Sette. (as)

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