“Brain and Immunity: Insights into Parkinson’s Disease and Multiple Sclerosis.”
Happy International Day of Immunology 2025!
In recent years, scientists have uncovered fascinating evidence revealing that the brain and immune system are much more interconnected than previously thought. This relationship has profound implications for our understanding of neurological diseases such as Parkinson’s disease, multiple sclerosis, Alzheimer’s, ALS, and even psychiatric conditions.
At ySSI, we spoke with InFLAMES flagship researchers Prof. Eleanor Coffey, who focuses on Parkinson’s disease, and Prof. Laura Airas, who studies Multiple Sclerosis, to learn about the latest advances in neuroimmunology. Let’s dive into some of the latest insights into the growing field of neuroimmunology of these diseases.
How the Brain and Immunity Are Linked
While neurons are the brain’s primary cells, brain has its own resident immune cells known as microglia. They act as the brain’s first line of defense, becoming activated by pathogens or injury. Upon activation, they change shape, migrate to affected areas, and release pro-inflammatory cytokines such as IL-6, IL-1, and TNF-alpha.
However, during disease states or when the blood-brain barrier is compromised, peripheral immune cells — including T cells, B cells, neutrophils, macrophages, and natural killer (NK) cells — can infiltrate the brain. This phenomenon has been observed in conditions like Parkinson’s disease and Multiple sclerosis. This immune cell infiltration is an active area of research which holds the key for novel diagnostic methods and disease modifying therapies.
A groundbreaking Nature study further revealed that brainstem neurons regulate immune responses via the vagus nerve, suggesting that the brain constantly monitors and adjusts immune activity.
Prof. Eleanor Coffey research: Parkinson’s Disease
Our research primarily focuses on understanding the mechanisms behind Parkinson’s disease (PD), a neurodegenerative disorder affecting dopaminergic neurons in a brain region called the substantia nigra. The death of these neurons leads to the classic motor symptoms seen in PD.
Interestingly, inflammation appears to be an early hallmark of Parkinson’s — sometimes emerging up to 20 years before clinical symptoms. Recent theories propose that “inflammaging” and immune exhaustion contribute to disease progression.
To study this, we analyze peripheral blood mononuclear cells (PBMCs) from Parkinson’s patients, since these cells are rich in lysosomes — organelles responsible for breaking down and recycling cellular material. Research has shown that lysosomal dysfunction is common in Parkinson’s and may lead to the accumulation of toxic alpha-synuclein aggregates, forming Lewy bodies, a key pathological hallmark.
By performing multi-layered proteomic analyses on samples from patients at risk of developing Parkinson’s (before they show cardinal symptoms), we aim to uncover early biomarkers and identify disrupted cellular processes. Our cohort is particularly valuable because it includes extensive clinical data, >50 clinical feature measurements in each participant at multiple time points. This includes immune cell profiling, brain scans (SPECT and MRI), motor function, hyposmia and synuclein aggregation assessments. This allows us to track disease progression more accurately and associate specific proteomic changes with immunological features and clinical outcomes.
One immune-related phenomenon we focus on is citrullination, a post-translational modification that can signal cell death, autoimmune activity, or overactive immune responses — all relevant to the inflammatory environment of Parkinson’s.
Prof. Laura Airas research: Multiple Sclerosis (MS)
Our research also centers on multiple sclerosis (MS) — another prime example of the intricate interplay between the immune system and the brain.
In MS, immune cells breach the blood-brain barrier and attack the central nervous system, leading to inflammation, nerve damage, and brain lesions. The disease is unpredictable: some patients experience mild symptoms, while others face profound challenges such as vision loss, speech impairment, or difficulty walking. MS highlights the complex, two-way relationship between brain function and immune activity.
We are particularly focused on investigating microglia — the brain’s resident immune cells — whose behavior can shift between harmful and protective roles. At the Turku PET Center at the University of Turku, Finland, we are developing and applying novel MRI techniques and new PET ligands to track microglial activity at the sites of brain lesions. Visualizing microglia may offer a powerful imaging biomarker for monitoring MS progression.
Additionally, we are examining peripheral blood immune cells from MS patients, aiming to link peripheral immune alterations to brain pathology. Our goal is to bridge imaging findings to clinical outcomes and ultimately adapt these methods for use in clinical trials and patient care. We believe these approaches can be extended to other CNS inflammatory diseases as well.
The Future of Neuroimmunology
The future of neuroimmunology is incredibly promising. Immune dysfunction is now recognized as a key player not just in classical neurodegenerative diseases like Parkinson’s, Alzheimer’s, ALS, and MS, but also in psychiatric disorders.
Emerging technologies, such as immunopeptidomic screening, citrullination discovery analysis, and advanced imaging biomarkers like novel PET ligands, are opening new avenues for research. These tools allow us to identify specific autoimmune components, monitor disease progression in real time, and uncover new therapeutic targets.
In Parkinson’s disease, for example, anti-inflammatory treatments such as inflammasome inhibitors are actively being explored. In MS, imaging microglial activity could revolutionize how we track disease activity and personalize treatments.
Importantly, the fact that immune components in the blood are more accessible than brain tissue suggests a new realm of pharmacologically reachable targets for brain diseases — a shift that could dramatically change how neurological disorders are treated.
For all these reasons, the future of neuroimmunology is not just bright — it is transformative. Each discovery brings us closer to new diagnostics, treatments, and, ultimately, to improving patients’ lives.
Eleanor Coffey
InFLAMES Flagship
Research Director (Forskningschef) at Åbo Akademi University, Finland
Kinase function in Brain research, Parkinson’s Disease research
Laura Airas
InFLAMES Flagship
Professor, Turku PET Centre
Professor of Neuroimmunology at University of Turku, Finland
Multiple sclerosis research, @multiplesclerosisresearchfinland
Young Scandinavian Society for Immunology (ySSI)
Yssi.inbox@gmail.com