Studying Abnormalities of Immune System Aging in Parkinson's Disease

Study Rationale:
While immune cells protect us from infection, they can also cause damage by inadvertently responding to other, non-infectious events. Such immune response occurs in Parkinson's disease (PD) and likely contributes to disease progression through promoting inflammation in the brain. As we age, the immune system becomes more "experienced," that is, effective in fighting infections encountered in the past but less able to respond to new infections. This aging of the immune system may play a role in PD. We have found evidence suggesting that markers -- objective measures -- of aging on the surface of T cells (a type of immune cell) in people with Parkinson's differ from those in healthy people of a similar age.

Hypothesis:
The present study will test a theory that typical age-related changes in T cells protect against PD by limiting the ability of the immune system to become activated and cause brain inflammation.

Study Design:
The study will involve 60 people recently diagnosed Parkinson's and 60 healthy people of the same age. Blood samples collected from these people will be used to measure aging markers on the surface of T cells. We will also analyze aging markers in the DNA and internal proteins of these cells. We will test whether these markers differ in individuals with and without PD. We will also investigate whether the aging markers are linked with expected disease progression calculated using simple clinical predictors that we have previously identified.

Impact on Diagnosis/Treatment of Parkinson's disease:
This project has a potential to identify a T-cell-based immune signature -- a set of indicators -- present in early Parkinson's. The signature will indicate how quickly the disease will progress. It could also identify patients who might benefit from future treatments targeting the immune system to slow disease progression.

Next Steps for Development:
If this study is successful, next steps would involve conducting a long-term study to confirm that the identified T-cell signature predicts disease progression and investigate whether the signature has potential to become a target for new therapies.