T cells are an important part of the immune system, fighting off infections and harmful invaders.
However, sometimes these cells mistakenly attack the body’s own healthy tissues, leading to autoimmune diseases such as type 1 diabetes, rheumatoid arthritis, and inflammatory bowel disease.
In recent years, scientists have found signs that T cells may also be involved in the development of Parkinson’s disease.
Research from the La Jolla Institute for Immunology (LJI), led by Professor Alessandro Sette, has shown that many people with Parkinson’s have T cells that target brain proteins like alpha-synuclein and PINK1, which are found on nerve cells that are particularly vulnerable in the disease.
Earlier work from Sette’s lab, published in npj Parkinson’s Disease, identified which subtypes of T cells target alpha-synuclein. But researchers still didn’t know when T cells begin to play a role in the disease’s development. “
We can see these reactive T cells after someone is diagnosed with Parkinson’s,” says Emil Johansson, Ph.D., a visiting scientist in Sette’s lab. “The question is, what’s happening before that?”
A new study from Sette and his colleagues now provides an answer. The team found that harmful T cell activity is at its highest during the “prodromal” phase of Parkinson’s — the years or even decades before patients show obvious symptoms, such as tremors or memory problems.
“This T cell response could serve as a marker for early treatment, even before symptoms begin,” says Sette. “Treating Parkinson’s early could lead to much better outcomes.”
The prodromal period is difficult to detect, but researchers studied people who were at high risk of developing Parkinson’s. These volunteers had genetic risk factors or early warning signs such as loss of smell and disrupted REM sleep, both linked to Parkinson’s.
The team analyzed blood samples using a lab technique called Fluorospot. This allowed them to see which participants had high levels of T cells that reacted to alpha-synuclein or PINK1. They discovered that these reactive T cells were most active well before the onset of noticeable symptoms, with PINK1-reactive T cells reaching their peak before diagnosis.
Still, the scientists stress that the findings don’t prove that T cells cause Parkinson’s. “We don’t yet know if the immune reaction is causing the nerve damage or if it’s a response to damage that’s already happening,” says Sette. “But the timing of this T cell activity is very interesting and suggests a possible role.”
The research could lead to new early diagnostic tests and even new treatments. LJI scientists are now exploring ways to block harmful inflammation and protect brain cells. “Some T cells may actually help reduce inflammation,” Johansson explains. “We want to know if we can boost these protective T cells and reduce the harmful ones.”
Sette’s team is also studying the role of T cells in other brain diseases like Alzheimer’s. “We’re very interested in finding early markers in these diseases too,” says Sette. “Catching them early is the key to better treatments.”
If you care about Parkinson’s disease, please read studies that Vitamin B may slow down cognitive decline, and Mediterranean diet could help lower risk of Parkinson’s.
For more health information, please see recent studies about how wheat gluten might be influencing our brain health, and Olive oil: a daily dose for better brain health.
The study is published in npj Parkinson’s Disease.
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