Parkinson's disease is best known for its effects on the central nervous system. In addition, recent scientific advances generally emphasize the role of the immune system in the presence and development of the disease.
In a study published today in Brain, researchers led by Université de Montréal associate professor of neuroscience Martine Tétreault show that some cell types in the immune system are activated more in patients who have Parkinson's.
"Thanks to a new technology called single-cell RNA-seq, we can differentiate the cellular subtypes and observe gene expression at the cellular level for each cell," explained Tétreault, a research scientist at the CRCHUM, Université de Montréal's affiliated hospital research centre.
"We found that in Parkinson's patients, immune cells in the blood were activated and overexpressed genes associated with stress responses," she said. "Together, these biomarkers form the signature of the disease."
Tétreault conducted the study with three co-first authors: Gaël Moquin-Beaubry, a former postdoctoral fellow in her lab, and current PhD candidates Lovatiana Andriamboavonjy and Sébastien Audet.
Noting the current lack of clinical biomarkers needed to diagnose Parkinson's, the researchers believe that knowing the disease's unique signature could help clinical teams diagnose it early on, from a blood sample.
The set of biomarkers could also make it easier to distinguish the disease from other similar rare diseases, especially Parkinsonian syndromes such as progressive supranuclear palsy (PSP), and multiple system atrophy (MSA).
14 patients tested
In their study, the research team analyzed blood samples from 14 CHUM patients with a confirmed diagnosis of Parkinson's and six patients presenting with Parkinsonian syndromes, comparing them with a control group of 10 healthy people.
"In our study, the gene signature of the disease allowed us to distinguish between patients with Parkinson's disease and those with Parkinsonian syndromes," said Tétreault. "These biomarkers could improve diagnostic reliability or facilitate participant selection for clinical trials testing the efficacy of a drug for this disease."
Her research team is now making available to other scientists a complete atlas of immune system cellular subtypes found in healthy individuals and people with Parkinson's.
In 2024, approximately 110,000 Canadians were living with Parkinson's disease. By 2034, that number is expected to grow to around 150,000.
Author: Bruno Geoffroy
##
About this study
" Mapping the peripheral immune landscape of Parkinson's disease patients with single-cell sequencing ," by Gaël Moquin-Beaudry, Lovatiana Andriamboavonjy et Sébastien Audet under the supervision of Martine Tétreault et al., was published May 26, 2025, in Brain. Funding was provided by the Courtois Foundation and the Weston Family Foundation. The researchers were supported by colleagues in the CHUM's neurology unit, particularly Drs. Michel Panisset, Sylvain Chouinard and Antoine Duquette.
Martine Tétreault and her team would like to thank the patients and their families for their participation in this study.
About the CHUM Research Centre (CRCHUM)
Université de Montréal's affiliated hospital research centre, the CRCHUM, is one of North America's leading hospital research centres. It strives to improve the health of adults through a continuum of research spanning disciplines such as basic science, clinical research and population health. About 2,130 people work at CRCHUM. These include more than 550 researchers and nearly 530 graduate students and postdoctoral fellows. crchum.com
About Université de Montréal
Deeply rooted in Montréal and dedicated to its international mission, Université de Montréal is one of the top universities in the French-speaking world. Founded in 1878, Université de Montréal today has 13 faculties and schools, and together with its two affiliated schools, HEC Montréal and Polytechnique Montréal, constitutes the largest centre of higher education and research in Québec and one of the major centres in North America. It brings together 2,300 professors and researchers and has close to 67,000 students. umontreal.ca
