The brain is protected by tightly regulated barriers, including the blood-brain (BBB), blood-cerebrospinal fluid (CSF), and arachnoid barrier. These barriers are maintained by tight junctions between barrier-forming cells and are monitored by patrolling immune cells. However, despite these defenses, peripheral inflammatory stimuli can still impact the brain, potentially contributing to the onset and progression of various neurological disorders, such as Parkinson's and Alzheimer's disease. This project aims to study how low-grade inflammation, viral infections, and the gut microbiome influence neuroinflammation and disease development. To achieve this, we will combine mouse models of neurological disorders with inflammatory triggers and microbiota alterations and analyze immune cell trafficking, and the role of (bacterial) extracellular vesicles and metabolites in brain inflammation and disease symptoms. This will help clarify how peripheral inflammation drives neurological disease.