Tu130 - Central Nervous System-specific Chimeric Antigen Receptor Regulatory T Cells for the Therapy of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic demyelinating autoimmune disease targeting the neurons of the central nervous system (CNS). So far, there is no cellular therapy for this incurable disease. Therefore, we are developing an approach using the immunosuppressive abilities of regulatory T cells (Tregs) combined with the antigen specificity of chimeric antigen receptors (CARs) to induce tolerance against self-antigens directly at the inflamed site. This strategy has the advantage of no systemic inhibition of the immune system compared to the currently used immunosuppressive drugs.

Utilizing antibody phage display libraries we screened for single chain variable fragments (scFvs) binding to a human extracellular target protein of the CNS, which plays a pivotal role in MS pathology. To secure cross-reactivity we tested the binding ability of the generated scFvs on murine brain sections using immunohistochemistry. Binding scFvs were cloned into different second generation CAR constructs with a CD28 and a CD3zeta signaling domain and subsequently tested their functionality in a NFAT-GFP reporter T cell line. This assay demonstrated that our CARs were able to specifically recognize not only the antigen presented on transfected HEK cells but also the naturally occurring antigen in murine brain lysates. In contrast, CAR signaling was not activated on untransfected HEKs or murine liver lysates, which both do not express the target of interest. Generated CAR-Tregs were also antigen-specific, had a normal Treg phenotype, were suppressive and were stable in vivo. Thus, target-specific CAR-Tregs represent a promising option for tissue-specific immune regulators without compromising the general immune response.