Abstract Text: Pathologic T cells drive many diseases, including autoimmune diseases like type 1 diabetes (T1D). Currently approved treatments are limited in their ability to differentiate pathogenic from non-pathogenic T cells, causing significant risk of adverse effects including infection and malignancy. A potential solution are chimeric antigen receptors (CARs), synthetic constructs that repurpose T cell cytotoxicity specifically against target-bearing cells. We hypothesized this technology could be developed for targeted depletion of specific CD8 T cells populations.
Working within the canonical ovalbumin system, we have developed two novel CAR designs which target CD8 T cells via their T cell receptor (TCR). The anti-Vβ5 CAR is a second-generation CAR with traditional extracellular scFv-domain that targets the β-chain(Vβ5) of the OT-I TCR. The OVA-MHC-I-Bait CAR replaces the scFv-domain with an extracellular MHC(H-2Kb) complex with cognate epitope. Using in vitro co-culture assays, both anti-Vβ5 and OVA-MHC-I-Bait CAR T cells demonstrate activation by and robust killing of OT-I T cells despite expected activation of OT-I T cells. Both CARs demonstrate in vivo killing of OVA-reactive CD8 T cells generated via adjuvanted-ovalbumin vaccination, resulting in decreased protection against ovalbumin-expressing Listeria monocytogenes. We found that adoptive transfer of OVA-reactive T cells from OVA-vaccinated mice will induce T1D in RIP-mOVA mice. Subsequent administration of both CARs was able to prevent T1D.
In conclusion, we have developed two TCR-targeting CARs which precisely kill specific CD8 T cells with resultant functional immune changes including altered microbial immunity and prevention of T1D. Durable, specific depletion of CD8 T cells has broad therapeutic applications.
