This project focused on engineering primary human regulatory T cells (Tregs) with a chimeric antigen receptor (CAR) to create a therapy for type 1 diabetes (T1D). These CAR Tregs can target and protect transplanted allogeneic beta cells from allogeneic immune rejection and autoimmunity. Yet, finding a unique target protein that is only present in one place and nowhere else is very challenging. Moreover, there is a shortage of high-quality cadaveric primary human islets for transplantation. To circumvent these challenges, we co-engineered stem cells and Tregs so that the engineered Tregs protect engineered stem cell-derived tissues.
Specifically, we genetically modified stem cells to express a unique inert protein ligand on their surface. We then differentiated them into beta cells still expressing that ligand. In parallel, we isolated Tregs (T-Regulatory cells) from blood and genetically modified them with a chimeric antigen receptor (CAR) such that they now recognize the unique ligand on the engineered beta cells. We showed that this dual engineering allows for localized protection from immune attack of ligand-expressing human beta cells by ligand-specific human CAR Tregs in humanized mice. Moreover, we have identified CAR affinity as a key parameter influencing CAR Treg phenotype and function. Ongoing experiments are developing new unique ligands and new CARs specific to those ligands to continue dissecting CAR Treg biology and design the next generation of engineered cell therapies for T1D.
Advancements in T1D research
This project addressed both the beta cell loss and the immune response aspects of type 1 diabetes in this new therapeutic strategy, with some other challenges addressed as well:
- Shortage of high-quality cadaveric islets -> we used stem cell-derived beta cells, an off-the-shelf inexhaustible resource
- Islet transplants get rejected by T1D recipients due to allogeneic rejection (the islets and the recipient are not matched) and autoimmunity (the patient’s immune system destroys beta cells) -> we protected the beta cells from immune attack with antigen-specific regulatory T cells (Tregs)
- Tregs work well when they are antigen-specific, but antigen-specific Tregs are very rare and sometimes the antigen is unknown -> we used chimeric antigen receptor regulatory T cells (CAR Tregs) which can be generated to bind to any surface antigen of choice
- it is extremely hard to find a single cell surface protein that is present in islets or beta cells and nowhere else in the body -> we modified the stem cells to introduce a unique bait than no other cell in the recipient’s body will have and then made a CAR speciifc to that bait and put it in Tregs
Click HEREÂ to view a summary of his study, as reported by his institution, Medical University of South Carolina.
This project’s findings were published in greater detail here in CELL MAGAZINE.
Publications acknowledging DRC support so far:
Skartsis*, N., Muller, Y.D., Ferreira, L.M.R., 2023. Regulatory T cell homeostasis: requisite signals and implications for clinical development of biologics. Clin Immunol 246:109201
Skartsis*, N., Ferreira, L.M.R., Tang, Q., 2022. The dichotomous roles of TNFa signaling in CD4+ T cells. Front Immunol 13:1042622.
Ghobadinezhad, F., Ebrahimi, N., Mozaffari, F., Moradi, N., Beiranvand, S., Pournazari, M., Rezaei-Tazangi, F., Khorram, R., Afshinpour, M., Robino, R.A., Aref*, A.R., Ferreira*, L.M.R., 2022. The emerging role of regulatory cell-based therapy in autoimmune disease. Front Immunol 13:1075813
Zimmerman, C.M., Robino, R.A., Cochrane R.W., Dominguez, M.D., Ferreira*, L.M.R., 2024. Redirecting human conventional and regulatory T cells using chimeric antigen receptors. Methods Mol Biol 2748:201-241
Barra, J.M., Robino, R.A., Castro-Gutierrez, R., Proia, J., Russ*, H.A., Ferreira*, L.M.R., 2024. Combinatorial genetic engineering strategy for immune protection of stem cell-derived beta cells by chimeric antigen receptor regulatory T cells. Cell Rep 43 (11):114994
Cochrane, R.W., Robino, R.A., Granger, B., Allen, E., Vaena, S., Romeo, M.J., de Cubas, A.A., Berto, S., Ferreira*, L.M.R., 2024. High affinity chimeric antigen receptor signaling induces an inflammatory program in human regulatory T cells. Mol Ther Methods Clin Dev 32(4): 101385
