Graduate Student University of Kansas Medical Center Kansas City, Missouri, United States
Disclosure(s):
Elly Puckett: No financial relationships to disclose
Introduction/Rationale: Type 1 diabetes (T1D) is an autoimmune disease characterized by the destruction of β-cells in the pancreatic islets, resulting in insulin deficiency. Currently the best treatment option for T1D is exogenous insulin, which regulates blood glucose levels, but does not change the underlying disease. The increasing number of T1D diagnoses highlight the need for novel therapies. An area of growing interest is the use of regulatory T cells (Tregs) to suppress autoreactive T cells. Clinical trials involving the transfer of autologous ex vivo expanded polyclonal CD4+ Tregs have shown this approach to be safe; however, it has limitations. These include challenges with ex vivo Treg expansion, antigen specificity, loss of immunosuppressive activity, and inherent Treg functional defects due to genetic deficiencies in autoimmune patients.
Methods: Our group has developed a patented protocol for generating engineered Tregs (eTregs) by expressing two transcription factors critical for Treg function, FOXP3 and Helios in conventional T cells. We hypothesize that our FOXP3+Helios+ eTregs can suppress the islet-specific reactivity of cytotoxic CD8+ T cells (CTLs). To test this hypothesis, we have generated CTLs specific for an islet-specific antigen and FOXP3+Helios+ eTregs, as well as isolated natural Tregs (nTregs), all from the same donor. We then compared the ability of the eTregs with that of nTregs to suppress CTL reactivity against the human β cell line βlox5.
Results: Preliminary experiments revealed that both the nTregs and eTregs can suppress the cytotoxic function and cytokine secretion of the islet-specific CTLs. Separating the Tregs and CTLs using transwell inserts abrogated the suppressive effect, indicating that suppression is mediated by a cell contact-dependent mechanism.
Conclusion: These data indicate that FOXP3+Helios+ engineered Tregs can effectively suppress islet specific CTL responses in vitro and support the continued investigation of eTregs as a potential cell-based immunotherapy for T1D.
