Stem Cell-Derived Tissue-Associated Regulatory T Cells Suppress Autoimmune Diabetes

Abstract

Pluripotent stem cells (PSCs) can be utilized to obtain a renewable source of healthy regulatory T cells (Tregs) to treat autoimmune diabetes as they have the ability to create nearly entire cell types in the body, including Tregs. However, the right conditions for the development of auto antigen (Ag)-specific Tregs from PSCs (i.e., PSC-Tregs) has not been fully defined. Auto Ag-specific PSC-Tregs can be programmed to be tissue-associated and infiltrate to local inflamed tissues (e.g., islets) to suppress autoimmune responses after adoptive transfer, thus preventing possible overall immunosuppression from non-specific Tregs. In this study, a new approach was developed to generate functional auto Ag-specific Tregs from induced PSC (iPSCs), i.e., iPSC-Tregs, which have the ability to suppress autoimmunity in a murine model of autoimmune diabetes in auto Ag-associated fashion. Murine iPSCs were retrovirally transduced with a DsRed reporter construct containing genes of ovalbumin (OVA)-specific T cell receptor (TCR) and the transcriptional factor FoxP3. The DsRed+ iPSCs were in vitro differentiated into OVA-specific iPSC-Tregs with an OP9 stromal cell line in the presence of recombinant cytokines. A double transgenic (Tg) mouse model of autoimmune diabetes was established in F1 mice in which the first generation from RIP-OVA Tg mice that were crossed with OT-I T cell receptor (TCR) Tg mice was challenged with vaccinia viruses expressing OVA (VV-OVA). Adoptive transfer of OVA-specific iPSC-Tregs dramatically suppressed autoimmunity in the OVA-induced model of autoimmune diabetes, including the inflammation and prevents the insulin-secreting pancreatic beta cells from destruction. Of note, we demonstrated that the adoptive transfer significantly reduced the higher ratio of CD8+ to CD4+ T cells in diabetic mice. These results indicate that stem cells can be used to develop auto Ag-specific Tregs, which have a therapeutic potential for autoimmune diabetes. Disclosure J.J. Song: None.