Thymic regulatory T cells (tTregs) and induced regulatory T cells (iTregs) suppress murine acute graft-versus-host disease (GVHD). Previously, we demonstrated that the plasmacytoid dendritic cell indoleamine 2,3-dioxygenase (IDO) fosters the in vitro development of human iTregs via tryptophan depletion and kynurenine (Kyn) metabolites. We now show that stimulation of naïve CD4+ T cells in low tryptophan (low Trp) plus Kyn supports human iTreg generation. In vitro, low Trp + Kyn iTregs and tTregs potently suppress T effector cell proliferation equivalently but are phenotypically distinct. Compared with tTregs or T effector cells, bioenergetics profiling reveals that low Trp + Kyn iTregs have increased basal glycolysis and oxidative phosphorylation and use glutaminolysis as an energy source. Low Trp + Kyn iTreg viability was reliant on interleukin (IL)-2 in vitro. Although in vivo IL-2 administration increased low Trp + Kyn iTreg persistence on adoptive transfer into immunodeficient mice given peripheral blood mononuclear cells to induce GVHD, IL-2–supported iTregs did not improve recipient survival. We conclude that low Trp + Kyn create suppressive iTregs that have high metabolic needs that will need to be addressed before clinical translation.
Bibliographical noteFunding Information:
The authors thank Dr. David A. Bernlohr and Rocio Foncea (Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota) and the Minnesota Obesity Center (National Institutes of Health [NIH] P30 DK050456) for assistance in Seahorse experiments and Charles Lehnen (Department of Pediatrics, University of Minnesota) for technical assistance and animal handling. This work was supported in part by research grants from the Children’s Cancer Research Fund and Blood and Marrow Transplant Research Fund (K.L.H.), Leukemia and Lymphoma Translational Research Grant R6029–07 (B.R.B.), NIH grants R01 HL114512-01 (M.L.M, K.L.H.), P01 AI056299 (B.R.B.), NCI P01 CA067493 (B.R.B., J.E.W., J.S.M.) and NHLBI N01HB037164 (J.E.W., J.S.M.), R01 CA157971, (to A.K.) and F31 award, CA177119 (to E.A.H.). This work was also funded in part by an Infrastructure grant (for the XFe96 Seahorse) from the University of Minnesota Academic Health Center (to A.K.) from the JDRF Collaborative Centers for Cell Therapy and the JDRF Center on Cord Blood Therapies for Type 1 Diabetes (J.L.R., C.H.J.). This work was supported in part by an NIH Clinical and Translational Science Award to the University of Minnesota (8UL1TR000114) and an NIH P30 CA77598 using the shared resource Flow Cytometry Core from the Masonic Cancer Center, University of Minnesota.
- T cell biology
- basic (laboratory) research/science
- bone marrow/hematopoietic stem cell transplantation
- graft-versus-host disease (GVHD)
- immune regulation
- immunosuppression/immune modulation
- tolerance: clinical
- translational research/science