Investigating the cellular and molecular mechanisms of periventricular inflammation in neuroinflammatory CNS - PROJECT ABSTRACT The goal of the proposal is to understand the cellular and molecular mechanisms driving periventricular inflammation in demyelinating disease and define the role of ependymal cell (EPC) derived complement component 3 (C3) in mediating this process. Periventricular inflammation has been identified as an early event in many neurodegenerative diseases. This is evident in both animal models and human diseases. For example, periventricular white matter hyperintensities (PVWMHs) are commonly observed on MRI scans in conditions such as multiple sclerosis (MS), Alzheimer’s disease, and vascular dementias in humans. Additionally, cerebrospinal fluid (CSF), which is produced within the ventricles, often contains inflammatory mediators indicative of neuroinflammation early in disease, which is often preceding cognitive symptoms. Despite these findings, the cellular and molecular mechanisms driving periventricular inflammation remain poorly understood. Our preliminary data suggest that ependymal cells (EPCs) play a key role in this process by upregulating complement component 3 (C3). C3 is particularly interesting as we and others have shown that it can drive synapse removal in MS and other neurodegenerative diseases, and it is has been implicated in regulating inflammatory processes more generally in the periphery. While past work has suggested astrocytes are the source of C3 in the brain, our data provide EPCs as another novel source that could play key roles in the neuroinflammatory process, which are highly tractable for therapeutic delivery given that half their cell body sits within the CSF. I will now tackle these new questions: 1) How does EPC-derived C3 contribute to periventricular inflammation? 2) How do ventricle-associated cells, including EPCs, astrocytes, choroid plexus, and microglia, interact with each other and the CSF to regulate neuroinflammation? I hypothesize that EPC-derived signaling, including C3, is a key driver of neuroinflammatory processes and that selective ablation of EPC-derived factors will mitigate these pathologies. With powerful in vivo tools to manipulate and monitor EPCs combined with comprehensive -omic strategies, I will now use an EPC-specific C3 deletion model to determine how loss of C3 in EPCs affects EAE severity, gliosis, demyelination, BBB integrity, and peripheral immune cell infiltration (Aim 1). I will also employ single-cell RNA sequencing (scRNA- seq) and CSF proteomics to define intercellular signaling networks between periventricular cells driving neuroinflammation and disease progression (Aim 2). Through these studies, I will receive training in in vivo neuroimaging from Dr. Shazeeb and proteomics from Dr. Lehtinen. I will also receive training in neuroinflammation, molecular genetics, transcriptomics, and bioinformatics from my sponsor Dr. Schafer, with clinical insights from my co-sponsor Dr. McManus and collaborator Dr. Hemond. Together, this project will advance our understanding of periventricular inflammation in neurodegenerative diseases and provide a foundation for my career as a physician-scientist focused on neuroinflammatory disorders.
