Functional Expansion of Regulatory T Cells to Limit CNS Autoimmunity

About This Grant

PROPOSAL SUMMARY Autoimmune diseases remain challenging to treat due to a lack of therapies that specifically target immune dysregulation without inducing generalized immunosuppression. Dysregulated immunoregulatory networks drive autoimmune disorders and are often associated with imbalances in regulatory T (Treg) and effector T (Teff) cells. Treg cell therapy or selective expansion of Treg cells in vivo can shift the Treg/Teff balance towards Treg cells to resolve ongoing inflammation and promote tissue repair to restore function and improve overall quality of life. However, selective and functional expansion of Treg cells during ongoing autoimmune conditions (i.e., therapeutic use) has been challenging. This is mainly because immune regulatory networks are complex, and our knowledge of the cellular and molecular choreography of Tregs in tissues is still evolving, particularly in the context of autoinflammatory disorders of the central nervous system (CNS). Treg cells hold tremendous potential to not only stop the course of the disease but also to restore neuronal function by inducing the repair of damaged axons. Therefore, our main objective is to investigate key principles of expansion of Treg cells to limit the pathophysiology of CNS autoimmunity and promote myelin repair. Capitalizing on the multiphoton imaging, state-of-the-art ratiometric calcium indicator, Salsa6f, label-free detection of myelin lesions, we aim to identify the role of combinatorial activation of T cell receptor (TCR), IL-2 signaling, and TGF-beta signaling for expansion of Treg cells in vivo. Using immunomodulatory Treg expanding biologics (TREBs) and experimental autoimmune encephalomyelitis (EAE), a model of MS-like disease, we will determine target engagement, biodistribution, and immunosafety of combinatorial Treg-expanding biologics (Aim 1); and define cellular and molecular determinants of Treg expansion and evaluate therapeutic efficacy in models of CNS autoimmunity (Aim 2). We postulate that selective expansion of Treg cells is an ideal strategy to curb ongoing autoinflammatory responses while preserving the immune system’s ability to fight new infections and promoting tissue repair for functional recovery. Although our exploratory/developmental project aims to establish a mechanistic link between Treg expansion and clinical improvement during CNS autoimmunity, in a broader context, our studies will guide the rational design of Treg-targeting immunotherapies, accelerating translation into effective and safe treatments for MS and several other autoimmune conditions.