Epigenetic Modulation of Foxp3: Generation of CD4+CD25- T Cells with a Suppressor Phenotype
Year: 2009
Type: article
Abstract: Regulatory T cells (Tregs) contribute to the maintenance of self-tolerance. Major obstacles for their routine use in human clinical trials to reduce autoimmunity or GvHD include the low number of Tregs, low yields and efficiencies of purification and severe limitations maintaining suppressor function after ex vivo expansion. Foxp3 is the master gene responsible for the development and function of Tregs. Demethylated CpG islands within the Foxp3 locus of Tregs led us to investigate whether an FDA-approved demethylating agent, decitabine, could be used to enhance Foxp3 expression and convert non-Tregs cells into Tregs. Treatment of human CD4+CD25-FOXP3- T cells with decitabine induced FOXP3 expression. Real time RT-PCR demonstrated levels of mRNA for FOXP3 that were comparable to that seen in anti-CD3/CD28 bead-activated natural Tregs. This resulted in increased expression at the protein level in 60% of decitabine-treated cells (dcT). Decitabine also induced Foxp3 expression in 80% murine CD4+CD25- T cells. Consistent with these results, decitabine induced marked increased GFP expression in CD4+CD25- T cells from Foxp3-ires-GFP KI mice. In addition, decitabine injection into sub-lethally irradiated mice transplanted with TCD BM increased the percentage of CD4+Foxp3+ T cells in the spleens. Of note, dcT could potently suppress proliferation of CD4+CD25- T cells in vitro in response to both anti-CD3/CD28 bead activation and to allo-APC in mixed lymphocyte cultures. Transwell experiments demonstrated that the suppressor function of dcT is cell-contact dependent. Surprisingly, we found that their suppressive properties are independent of Foxp3 expression as evidenced by dcT from Foxp3 KO mice were equally suppressive as WT dcT. In a murine BMT model (B6→Balb/c), conventional T-cells (Tconv) (10 × 106) incubated with anti-CD3/CD28 beads and decitabine were found to promote enhanced engraftment with reduced GvHD, compared to mice receiving PBS-treated Tconv. In addition, addition of dcT with Tconv (1:1 ratio) resulted in decreased GvHD and improved survival, compared to Balb/c recipients receiving B6 Tconv and pbsT. In summary, decitabine-treatment enhanced Foxp3 expression in non-Tregs cells. These dcT efficiently suppressed the proliferation of allo-reactive T cells in vitro and mitigated GvHD in vivo. The suppressor function of dcT was cell-contact dependent but unexpectedly Foxp3-independent.
Authors: J. Choi, M. Schroeder, J. Ritchey, J.F. DiPersio
Institution: Washington University in St. Louis
Language: English
Topic: T-cell and B-cell Immunology
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,650
OpenAlex ID: W2144783060