PReS-FINAL-1011: Can repeated T cell receptor stimulation lead to epigenetic reprogramming of the treg-specific demethylated region in human conventional T cells?

Introduction Regulatory T (Treg) cells, vital to prevent autoimmune disease, can be identified by their expression of the forkhead box P3 (FoxP3) transcription factor. Human conventional T (Tconv) cells stimulated via the T cell receptor (TCR) can also express FoxP3. Although this can confer some intrinsic regulatory effects, controversy exists over whether FoxP3 expression alone gives rise to the Treg cell phenotype. Treg-specific demethylated region (TSDR) demethylation is thought to be a reliable marker of commitment to the Treg cell lineage. In most human studies, analysis of TSDR methylation status has been performed on bulk populations, where only a subpopulation of cells express FoxP3. However, TSDR demethylation may occur selectively in cells expressing the highest levels of FoxP3 protein. Previously, investigation of epigenetic modifications in FoxP3 human Tconv cells has been hampered by the inability to separate cells on the basis of FoxP3 expression. Recently, however, a protocol has been published detailing a method for DNA extraction from cells that have been fixed and stained for FoxP3, permitting more informative phenotyping of TSDR methylation status.