Engrafting human regulatory T cells with a flexible modular chimeric antigen receptor technology

Publication date: Available online 2 March 2018
Source:Journal of Autoimmunity
Author(s): Stefanie Koristka, Alexandra Kegler, Ralf Bergmann, Claudia Arndt, Anja Feldmann, Susann Albert, Marc Cartellieri, Armin Ehninger, Gerhard Ehninger, Jan Moritz Middeke, Martin Bornhäuser, Marc Schmitz, Jens Pietzsch, Katja Akgün, Tjalf Ziemssen, Jörg Steinbach, Michael P. Bachmann
As regulatory T cells (Tregs) play a fundamental role in immune homeostasis their adoptive transfer emerged as a promising treatment strategy for inflammation-related diseases. Preclinical animal models underline the superiority of antigen-specific Tregs compared to polyclonal cells. Here, we applied a modular chimeric antigen receptor (CAR) technology called UniCAR for generation of antigen-specific human Tregs. In contrast to conventional CARs, UniCAR-endowed Tregs are indirectly linked to their target cells via a separate targeting module (TM). Thus, transduced Tregs can be applied universally as their antigen-specificity is easily adjusted by TM exchange. Activation of UniCAR-engrafted Tregs occurred in strict dependence on the TM, facilitating a precise control over Treg activity. In order to augment efficacy and safety, different intracellular signaling domains were tested. Both 4-1BB (CD137) and CD28 costimulation induced strong suppressive function of genetically modified Tregs. However, in light of safety issues, UniCARs comprising a CD137-CD3ζ signaling domain emerged as constructs of choice for a clinical application of redirected Tregs. In that regard, Tregs isolated from patients suffering from autoimmune or inflammatory diseases were, for the first time, successfully engineered with UniCAR 137/ζ and efficiently suppressed patient-derived effector cells. Overall, the UniCAR platform represents a promising approach to improve Treg-based immunotherapies for tolerance induction.



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