ZAGREB, 16 March (Hina) – A team of Croatian scientists, doctors and clinicians has found that Parkinson’s disease is associated with measurable changes in specific immune cells in the blood, helping link the disease to inflammatory processes beyond the brain.
The research, published in the journal “Parkinson’s Disease” by Springer Nature, was conducted by experts from the Zagreb University Hospital Centre, the University of Zagreb School of Medicine, the Ruđer Bošković Institute and the Dr. Fran Mihaljević University Hospital for Infectious Diseases.
Parkinson’s disease is typically recognised by tremor, slowed movement and other motor difficulties, while processes in the brain that are not externally visible develop for years. One of these is chronic inflammation in the nervous system, which may influence the course of the disease.
The study examined the peripheral immune profile in Parkinson’s disease, focusing on changes in immune cell types and their activity patterns in the blood.
Researchers analysed two types of immune cells: dendritic cells, which detect danger signals and guide the overall immune response, and CD4+ T cells, which coordinate the body’s defence by regulating when immune responses should intensify or subside.
Blood samples from Parkinson’s patients and control participants were compared. Target immune cells were first isolated using magnetic separation and then analysed with flow cytometry and single-cell RNA sequencing, explained Sarah Meglaj Bakrać of the University of Zagreb School of Medicine.
This approach enabled detection of rare cell subgroups that are often lost in averaged results. Because highly specialised subtypes of CD4 T cells and dendritic cells are present in very small numbers in the blood, samples were enriched with these rare cells to allow more precise analysis.
Sarah Meglaj Bakrać and Katarina Mandić of the Ruđer Bošković Institute are the study’s first authors.
The clearest finding was the activation of a specific group of dendritic cells and CD4 T cells involved in immune processes in people with Parkinson’s disease.
A key part of the research was bioinformatic analysis conducted at Ruđer Bošković Institute. Katarina Mandić and Anja Barešić analysed gene expression in tens of thousands of individual cells using a supercomputer to identify differences between patients and the control group and pinpoint the genes, cell subgroups and biological processes most prominent in Parkinson’s disease.
According to Zagreb University Hospital Centre director Fran Borovečki, the results show that Parkinson’s disease is linked not only to changes in the brain but also to measurable alterations in the immune system in the blood consistent with inflammatory processes.
The researchers stressed that the study does not claim to have identified a new therapy, but highlights where to look and which immune components in the blood stand out most when comparing patients with healthy controls.
The study was carried out as part of the project “Molecular mechanisms of immune response and inflammasome activation in Parkinson’s disease”, funded by the Croatian Science Foundation.
