Human Th1 and Th17 Cells Exhibit Epigenetic Stability at Signature Cytokine and Transcription Factor Loci

Abstract

The linear model of Th cell lineage commitment is being revised due to reports that mature Th cells can trans-differentiate into alternate lineages. This ability of Th cells to reprogram is thought to be regulated by epigenetic mechanisms that control expression of transcription factors characteristic of opposing lineages. It is unclear, however, to what extent this new model of Th cell plasticity holds true in human Th cell subsets that develop under physiological conditions in vivo. We isolated in vivo-differentiated human Th1 and Th17 cells, as well as intermediate Th1/17 cells, and identified distinct epigenetic signatures at cytokine (IFNG and IL17A) and transcription factor (TBX21, RORC, and RORA) loci. We also examined the phenotypic and epigenetic stability of human Th17 cells exposed to Th1-polarizing conditions and found that although they could upregulate TBX21 and IFN-γ, this occurred without loss of IL-17 or RORC expression, and resulted in cells with a Th1/17 phenotype. Similarly, Th1 cells could upregulate IL-17 upon enforced expression of RORC2, but did not lose expression of IFN-γ or TBX21. Despite alterations in expression of these signature genes, epigenetic modifications were remarkably stable aside from the acquisition of active histone methylation marks at cytokine gene promoters. The limited capacity of human Th17 and Th1 cells to undergo complete lineage conversion suggests that the bipotent Th1/17 cells may arise from Th1 and/or Th17 cells. These data also question the broad applicability of the new model of Th cell lineage plasticity to in vivo-polarized human Th cell subsets.

TBX21-1993T/C (rs4794067) polymorphism is associated with increased risk of chronic periodontitis and increased T-bet expression in periodontal lesions, but does not significantly impact the IFN-g transcriptional level or the pattern of periodontophatic bacterial infection

“…27,28 As a matter of fact, while Th1 cells exhibit epigenetic stability at signature transcription factor loci level, a number of other factors such as chromatin modifications and intergenic noncoding RNAs (such as Tmevpg1) can decisively impact IFN-g production. 29,30 Nevertheless, it is worth noting that regardless of the TBX21 genotype, CP subjects exhibited an overall 10-fold increase in IFN-g expression compared with the H group, and T-bet and IFN-g levels presented a significant statistical correlation (even though such correlation was relatively weak) in periodontal lesions, reinforcing the association of T-bet with Th1 responses in situ. However, no clear association was observed between the TBX21 genotype with the clinical parameters of chronic periodontitis, or between T-bet and IFN-g expression levels and the clinical parameters of periodontitis.…”

Helios+ and Helios− Cells Coexist within the Natural FOXP3+ T Regulatory Cell Subset in Humans

“…5D-F). Surprisingly, following exposure to IL-12, the MFI of T-BET expression was similar in nTreg and Tconv cell clones, further illustrating the ease of T-BET expression in human T cells (20), even in FOXP3 + nTregs (34). The phenotype of the T cell clones was also tested following activation in Th17 polarizing conditions containing IL-6, IL-1b, and IL-23, but as we previously reported (20) these conditions did not induce any detectable IL-17 (data not shown).…”

“…DNA methylation was determined at the FOXP3 Treg-specific demethylated region (TSDR) within the FOXP3 promoter (18). Bisulfite conversion was performed as described (19,20), and converted DNA was used as a template for PCR with PyroMark DNA polymerase (Qiagen) with previously described primers modified for pyrosequencing (forward, 59-TGTTTGGGGGTAGAGGATTT-39; reverse, biotin-TTGGTTTAGGTGG-GGTGATA-39) (18). Pyrosequencing primers were designed using PyroMark Q24 software (Qiagen) (sequencing: 59-GATGTTTTTGGGATATAGATTA-39).…”

Demethylation of the RORC2 and IL17A in Human CD4+ T Lymphocytes Defines Th17 Origin of Nonclassic Th1 Cells

“…1B). We also looked at the transcription factors involved in Th17 and Th1 development, and to this end, we analyzed one ROI for RORC2 (RORC2 downstream (17)) and one for TBX21 (CNS-1). The analysis of DNA methylation status of the RORC2 downstream showed that whereas Th17, Th17/Th1, and nonclassic Th1 cells had a marked demethylation, naive CD4 + Th cells and classic Th1 cells were characterized by a complete methylation of this DNA region ( Fig.…”