| Source: |
Eskandari, S K, Sulkaj, I, Melo, M B, Li, N, Allos, H, Alhaddad, J B, Kollar, B, Borges, T J, Eskandari, A S, Zinter, M A, Cai, S, Assaker, J P, Choi, J Y, Al Dulaijan, B S, Mansouri, A, Haik, Y, Tannous, B A, van Son, W J, Leuvenink, H G D, Pomahac, B, Riella, L, Tang, L, Seelen, M A J, Irvine, D J & Azzi, J R 2020, 'Regulatory T cells engineered with TCR signaling-responsive IL-2 nanogels suppress alloimmunity in sites of antigen encounter', Science Translational Medicine, vol. 12, no. 569, 4744, pp. 1-16. https://doi.org/10.1126/scitranslmed.aaw4744 |
| Description: |
Adoptive cell transfer of ex vivo expanded regulatory T cells (T-r(egs)) has shown immense potential in animal models of auto- and alloimmunity. However, the effective translation of such T-reg therapies to the clinic has been slow. Because T-reg homeostasis is known to require continuous T cell receptor (TCR) ligation and exogenous interleukin-2 (IL-2), some investigators have explored the use of low-dose IL-2 injections to increase endogenous T-reg responses. Systemic IL-2 immunotherapy, however, can also lead to the activation of cytotoxic T lymphocytes and natural killer cells, causing adverse therapeutic outcomes. Here, we describe a drug delivery platform, which can be engineered to autostimulate T-regs with IL-2 in response to TCR-dependent activation, and thus activate these cells in sites of antigen encounter. To this end, protein nanogels (NGs) were synthesized with cleavable bis(N-hydroxysuccinimide) cross-linkers and IL-2/Fc fusion (IL-2) proteins to form particles that release IL-2 under reducing conditions, as found at the surface of T cells receiving stimulation through the TCR. T-regs surface-conjugated with IL-2 NGs were found to have preferential, allograft-protective effects relative to unmodified T-regs or T-regs stimulated with systemic IL-2. We demonstrate that murine and human NG-modified T-regs carrying an IL-2 cargo perform better than conventional T-regs in suppressing alloimmunity in murine and humanized mouse allotransplantation models. In all, the technology presented in this study has the potential to improve T-reg transfer therapy by enabling the regulated spatiotemporal provision of IL-2 to antigen-primed T-regs. |