Deep brain stimulation halts Parkinson’s disease-related immune dysregulation in the brain and peripheral blood

This research explores how Deep Brain Stimulation (DBS), a treatment for Parkinson's disease (PD), affects inflammation in both the brain and body. The researchers found that PD patients have lower levels of lymphocytes (important immune cells) in their blood compared to people without PD. While the exact reason isn't clear, these cells might be moving into the brain instead of staying in the blood, there could be changes in how these immune cells are regulated, or other immune cells might be increasing in number. The study revealed important connections between lymphocyte levels and disease progression. Lower levels were linked to worse motor symptoms in patients, and remarkably, by looking at a patient's lymphocyte levels early in their disease, doctors might be able to predict with 85% accuracy how their motor symptoms will develop over the next five years. The most exciting finding concerned DBS treatment itself - it can actually change the levels of immune cells in the body, reduce inflammation in both the brain and body, and specifically helps reduce certain inflammatory cells (Th17 cells) that are known to damage brain cells in PD. Using rat models of PD, the researchers discovered that changes in blood immune cells matched with brain cell damage, and that DBS reduced inflammation in the brain. This might explain why DBS helps improve movement symptoms. While the exact mechanism isn't fully understood yet, DBS might achieve these effects by changing how brain cells release chemical messengers (neurotransmitters), reducing stress signals in the brain, or affecting how immune cells and brain cells communicate with each other. This research suggests that DBS might help PD patients not just by improving movement, but also by reducing harmful inflammation throughout the body. These findings could potentially lead to new treatments that target the immune system to help slow down the progression of Parkinson's disease.