ORCID
http://orcid.org/0000-0002-3166-3929
Date of Award
Spring 5-15-2023
Degree Name
Doctor of Philosophy (PhD)
Degree Type
Dissertation
Abstract
Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system (CNS) that leads to demyelination, axonal damage, and neuronal loss. Patients are typically diagnosed early in adulthood and due to the chronic nature of the disease, will continue to develop symptoms over their lifetime. Currently available therapeutics for MS focus on symptomatic relief and reduce severity of relapses; however, they are unable to prevent disease progression or promote recovery. Therefore, there is a critical need to understand the biological mechanisms driving neuroinflammatory and neurodegenerative processes in MS and to translate these findings into novel therapeutic strategies.
Here we employ a commonly used murine model, experimental autoimmune encephalomyelitis (EAE), that replicates the neuroinflammatory phenotypes observed in MS. We first examine the role of astrocyte - T cell crosstalk in determining the location of lesions within the CNS. Using in vitro cultures, we show that Th17 associated cytokines upregulate VCAM-1 expression preferentially on brainstem astrocytes, while Th1 associated cytokines upregulate CXCR7 expression preferentially on spinal cord astrocytes. We then take advantage of different EAE models, which promote either spinal cord or hindbrain inflammation, to show that these regional differences in astrocyte gene expression are maintained in vivo and that astrocyte specific targeting of these localization cues diminishes lymphocyte entry into the corresponding CNS region (Chapter 2). We next examine a novel role for type III interferons (interferon lambda or IFNL) in maintaining chronic neuroinflammation. Using genetic knockdown and antibody mediated neutralization approaches, we show that ablation of IFNL signaling during EAE prevents chronic inflammation, decreases Th1 effector cell function within the CNS, and reduces axonal injury. Conditional deletion of the IFNL receptor on CD11c+ cells also results in improved recovery during EAE, suggesting that CD11c+ cells are critical targets of IFNL signaling. IFNL ligand and receptor levels are increased in lesions of MS patients compared with their normal appearing white matter, highlighting the relevance of our murine studies to human disease (Chapter 3). Lastly, we use a model of relapsing remitting EAE to show that targeting sphingosine-1-phosphate-receptor-2 (S1PR2) with a selective antagonist following disease onset diminishes severity of subsequent relapses and reduces immune cell infiltration into the CNS meninges. In vitro studies reveal that the S1P-S1PR2 signaling axis promotes CXCR4 - mediated transmigration of MS patient CD4+ T cells, highlighting a mechanism by which S1PR2 may promote disease (Chapter 4). Overall, our data explore the roles of key molecules driving different stages of CNS autoimmune disease and highlight their therapeutic potentials.
Language
English (en)
Chair and Committee
Robyn Klein
Committee Members
Anne Cross, Brian Edelson, Erik Musiek, John Russell,
Recommended Citation
Manivasagam, Sindhu, "Examining Therapeutic Targets for Central Nervous System Autoimmune Disease" (2023). Arts & Sciences Electronic Theses and Dissertations. 2885.
https://openscholarship.wustl.edu/art_sci_etds/2885