La Jolla immunologists discover a new timeline for Parkinson’s disease

A new study by La Jolla Institute for Immunology finds that T cells may allow for early detection of Parkinson’s cases before motor symptoms develop.

Researchers at the La Jolla Institute for Immunology have shown that tracking potentially harmful T cell reactivity may allow for early detection of Parkinson’s disease years before motor symptom development and diagnosis.

The May 26 study published in npj Parkinson’s Disease paper reveals the harmful T cell reactivity is highest during the “prodromal” period in Parkinson’s, which occurs during the years before patients receive a diagnosis.

The discovery follows previous LJI research that showed T cell responses, which can lead to autoimmune diseases such as type 1 diabetes, rheumatoid arthritis and inflammatory bowel disease, may also contribute to the development of Parkinson’s disease.

The laboratory team of LJI professor Alessandro Sette has found that many people with Parkinson’s disease have T cells that target key proteins, called alpha-synuclein and PINK1, on vulnerable brain cells.

Earlier this year, Sette and his colleagues published a study in npj Parkinson’s Disease that sheds light on exactly which subtypes of T cells target alpha-synuclein. Their findings offered further clues that T cell reactivity plays a role in Parkinson’s disease. Still, the scientists didn’t have a timeline to show when T cells might contribute to disease development.

“This T cell immunity could be a marker for early Parkinson’s treatment, even before people show symptoms,” Sette, the senior author on the new paper, said in a press release. “Treating Parkinson’s in the very early stages can lead to a better outcome.”

The prodromal period in Parkinson’s disease can last for decades before a person develops noticeable symptoms including tremors and cognitive impairments.

Because prodromal Parkinson’s disease is very difficult to detect, the LJI team studied T cell reactivity in research volunteers at high risk of developing Parkinson’s disease. These volunteers had genetic risk factors for Parkinson’s and some had symptoms such as disrupted REM sleep cycles and loss of sense of smell, which can be early signs of Parkinson’s disease development.

Sette and his colleagues found that potentially harmful T cells show up early on, well before the onset of noticeable motor symptoms.

Further study is needed to prove that T cells are driving the inflammation associated with Parkinson’s disease; the new research may guide the development of early diagnostic tools.