Dr. Anna Christina Dragon (Hannover/ DE), Agnes Bonifacius (Hannover/ DE), Stefan Lienenklaus (Hannover/ DE), Murielle Verboom (Hannover/ DE), Richard Taubert (Hannover/ DE), Fabio Ius (Hannover/ DE), Prof. Dr. Michael Hudecek (Würzburg/ DE), Professor Constanca Ferreira de Figueiredo (Hannover/ DE), Prof. Dr. Rainer Blasczyk (Hannover/ DE), Prof. Dr. Britta Eiz-Vesper (Hannover/ DE)
Background
One major complication after solid organ transplantation (SOT) is antibody-mediated rejection (AMR) by anti-donor HLA antibodies. However, the B-cell alloimmune response is only indirectly addressed by modern immunosuppression. Unselective B-cell depletion protocols are inefficient in preventing AMR and associated with an increased infection risk, emphasizing the need for a more precise targeting of alloreactive B cells.
Methods
B cells with anti-donor HLA specificity are uniquely characterized by expression of the corresponding B-cell receptors (BCRs). Using BCRs against a distinct HLA molecule as target, we redirected T cells towards alloreactive B cells by introducing a novel chimeric receptor comprising the respective HLA molecule fused to intracellular 4-1BB/CD3ξ signaling domains to generate T cells overcoming rejection by antibodies (CORA-Ts). As a proof-of-concept, CORA-Ts based on an HLA-A*02 molecule were generated and further modified to abrogate T-cell sensitization and confer resistance to immunosuppression. Their ability to recognize and selectively eliminate anti-HLA-A*02 B cells to limit antibody release was tested in vitro as well as in vivo.
Results
Upon co-cultivation with B-cell lines expressing and releasing anti-HLA-A*02 antibodies, CORA-Ts were specifically activated (expression of CD25, CD69, CD137), released pro-inflammatory molecules (e.g. IFN-γ, granzyme B), and exhibited strong cytotoxicity resulting in an effective reduction of the anti-HLA-A*02 antibody release. In a mouse model, CORA-Ts significantly reduced growth of an anti-HLA-A*02 hybridoma B-cell line. Modification of the HLA-A*02 α3-domain abrogated T-cell sensitization against the CORA receptor by prevention of CD8 binding. Additionally, CRISPR/Cas9-mediated knockouts of selected binding proteins endowed CORA-Ts with the ability to resist immunosuppressive treatment.
Conclusion
Our results demonstrate that CORA-Ts are able to specifically recognize and eliminate alloreactive B cells, and thus selectively prevent formation of anti-HLA antibodies even under immunosuppressive conditions. This suggests CORA-Ts as a potent novel approach to specifically combat AMR and to improve long-term graft survival in SOT patients while preserving their overall B-cell immunity.
Offenlegung Interessenkonflikt:
The authors declare no conflict of interest, except that authors A.C.D., C.F., R.B. and B. E.-V. submitted a patent application on CORA-Ts.