Development of citrullinated-vimentin-specific CAR for targeting Tregs to treat autoimmune rheumatoid arthritis

Abstract Rheumatoid arthritis (RA) is one of the most common chronic autoimmune diseases that is characterized by an aberrant inflammation of the synovial membrane that causes irreversible joint and bone damage. Regulatory T cells (Tregs) are defective in RA patients while adoptive transfer of expanded autologous Tregs efficiently reversed disease in collagen-induced arthritis (CIA), an animal model of RA. These studies strongly suggest that Treg therapy may be effective in the treatment of RA patients by reducing joint inflammation and inducing immune tolerance. However, clinical treatment with polyclonal Tregs may lead to general immunosuppression. Thus, the development of precise RA Ag-specific Tregs would increase specific activity, promote selective migration to the site of the abnormal inflammation and enhance their function. Thus, we engineered chimeric antigen receptor (CAR)-expressing Tregs specifically targeting an antigen present in the joint of RA patients to induce a localized and effective immunosuppressive response. We developed a single chain Fv directed against a posttranslational modified intermediate filament protein, citrullinated vimentin (CV), an antigen found, almost exclusively, in the extracellular matrix of the synovial tissue of the RA patients and implicated in the pathogenesis of the disease. The scFv was grafted into a functional CAR construct, transduced into human Tregs and shown to react with CV expressed in RA patient synovial fluid and CV-expressing cells. Studies are underway to demonstrate the functional activity of these CAR-expressing Tregs in in vivo mouse models a validation step in the development of a promising therapeutic tool to treat RA and potentially other autoimmune disorders.