The role of Vitamin C and TET dioxygenases in genome-wide features of regulatory T cells [ATAC-seq]
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ABSTRACT: TET enzymes are essential for the stability and function of regulatory T cells (Tregs), which maintain immune homeostasis and self-tolerance and express the lineage-determining transcription factor Foxp3. We previously showed that Vitamin C acts through TET enzymes to maintain the demethylated status of CNS2, a key intronic enhancer of the Foxp3 gene that is essential for the stability of Foxp3 expression both in vivo and in vitro. Here we show that Vitamin C enables genome-wide features of “induced” T regulatory cells (iTregs) in vitro that overlap with those induced by TET proteins during Treg differentiation in vivo. Vitamin C enhances IL-2 responsiveness in iTregs by increasing phospho-STAT5 levels, STAT5 occupancy and DNA demethylation at key Treg-specific enhancers, and maintains the stable expression of Treg-specific genes including Foxp3 and Il2ra. Our data will be relevant to future studies of the association between plasma Vitamin C levels, Treg function and autoimmunity in humans.
Project description:TET enzymes are essential for the stability and function of regulatory T cells (Tregs), which maintain immune homeostasis and self-tolerance and express the lineage-determining transcription factor Foxp3. We previously showed that Vitamin C acts through TET enzymes to maintain the demethylated status of CNS2, a key intronic enhancer of the Foxp3 gene that is essential for the stability of Foxp3 expression both in vivo and in vitro. Here we show that Vitamin C enables genome-wide features of “induced” T regulatory cells (iTregs) in vitro that overlap with those induced by TET proteins during Treg differentiation in vivo. Vitamin C enhances IL-2 responsiveness in iTregs by increasing phospho-STAT5 levels, STAT5 occupancy and DNA demethylation at key Treg-specific enhancers, and maintains the stable expression of Treg-specific genes including Foxp3 and Il2ra. Our data will be relevant to future studies of the association between plasma Vitamin C levels, Treg function and autoimmunity in humans.
Project description:TET enzymes are essential for the stability and function of regulatory T cells (Tregs), which maintain immune homeostasis and self-tolerance and express the lineage-determining transcription factor Foxp3. We previously showed that Vitamin C acts through TET enzymes to maintain the demethylated status of CNS2, a key intronic enhancer of the Foxp3 gene that is essential for the stability of Foxp3 expression both in vivo and in vitro. Here we show that Vitamin C enables genome-wide features of “induced” T regulatory cells (iTregs) in vitro that overlap with those induced by TET proteins during Treg differentiation in vivo. Vitamin C enhances IL-2 responsiveness in iTregs by increasing phospho-STAT5 levels, STAT5 occupancy and DNA demethylation at key Treg-specific enhancers, and maintains the stable expression of Treg-specific genes including Foxp3 and Il2ra. Our data will be relevant to future studies of the association between plasma Vitamin C levels, Treg function and autoimmunity in humans.
Project description:TET enzymes are essential for the stability and function of regulatory T cells (Tregs), which maintain immune homeostasis and self-tolerance and express the lineage-determining transcription factor Foxp3. We previously showed that Vitamin C acts through TET enzymes to maintain the demethylated status of CNS2, a key intronic enhancer of the Foxp3 gene that is essential for the stability of Foxp3 expression both in vivo and in vitro. Here we show that Vitamin C enables genome-wide features of “induced” T regulatory cells (iTregs) in vitro that overlap with those induced by TET proteins during Treg differentiation in vivo. Vitamin C enhances IL-2 responsiveness in iTregs by increasing phospho-STAT5 levels, STAT5 occupancy and DNA demethylation at key Treg-specific enhancers, and maintains the stable expression of Treg-specific genes including Foxp3 and Il2ra. Our data will be relevant to future studies of the association between plasma Vitamin C levels, Treg function and autoimmunity in humans.
Project description:Regulatory T (Treg) cells play an indispensable role in immune homeostasis. The development and function of Tregs are dependent on transcriptional factor Foxp3, but how constant expression of Foxp3 is maintained in Tregs is not clear. Here we show that ablation of the conserved non-coding DNA sequence 2 (CNS2) at the Foxp3 locus in mice led to spontaneous lymphoproliferative disease and exacerbation of experimental autoimmune encephalomyelitis (EAE). CNS2 is required for activated Treg cells to maintain elevated Foxp3 expression, which is critical for their suppressor function and lineage stability. Mechanistically, upon TCR stimulation, NFAT binds to both CNS2 and Foxp3 promoter and mediates the interaction between CNS2 and Foxp3 promoter. Our findings demonstrated an essential role for CNS2 in maintaining the stability and function of activated Treg cells and identified NFAT as a key mediator of its function. Gene expression was profiled in T regulatory cells (Treg) in WT and CNS2 knockout mice. CNS2 knockout mice lack a conserved non-coding DNA sequence 2 (CNS2) at the Foxp3 locus. Treg cells were further sorted into Foxp3-high and Foxp3-low populations based on the expression level of Foxp3. mRNA was profiled using RNA-Seq (unstranded, polyA+, SE100) in replicate for each condition
Project description:Regulatory T cells (Tregs) are critical for the maintenance of immune homeostasis and self‑tolerance, and can be therapeutically used for prevention of unwanted immune responses such as allotransplant rejection. Tregs are characterized by the expression of the transcription factor Foxp3, and recent work suggested that epigenetic imprinting of Foxp3 and other Treg‑specific epigenetic signatures genes is crucial for the stabilization of both Foxp3 expression and immunosuppressive properties within Tregs. Lately, Vitamin C was reported to enhance the activity of enzymes of the ten‑eleven‑translocation family, thereby fostering the demethylation of Foxp3 and other Treg‑specific epigenetic signatures genes in developing Tregs. Here, we in vitro generated alloantigen‑specific Foxp3+ Tregs (allo‑iTregs) in presence of vitamin C, and those Tregs showed a pronounced demethylation of Foxp3 and other Treg‑specific epigenetic signatures genes, accompanied with an enhanced stability of Foxp3 expression. However, RNA‑seq analysis revealed an only minor impact of Vitamin C on the transcriptome of allo‑iTregs. Importantly, when being tested in vivo in a highly immunogenic skin transplantation model vitamin C‑treated allo‑iTregs showed a superior suppressive capacity as compared to allo‑iTregs generated in absence of vitamin C. Together, our results might pave the way for the establishment of novel protocols for the in vitro generation of allo‑antigen specific Foxp3+ Tregs for therapeutic usage in transplantation medicine.
Project description:Regulatory T (Treg) cells play an indispensable role in immune homeostasis. The development and function of Tregs are dependent on transcriptional factor Foxp3, but how constant expression of Foxp3 is maintained in Tregs is not clear. Here we show that ablation of the conserved non-coding DNA sequence 2 (CNS2) at the Foxp3 locus in mice led to spontaneous lymphoproliferative disease and exacerbation of experimental autoimmune encephalomyelitis (EAE). CNS2 is required for activated Treg cells to maintain elevated Foxp3 expression, which is critical for their suppressor function and lineage stability. Mechanistically, upon TCR stimulation, NFAT binds to both CNS2 and Foxp3 promoter and mediates the interaction between CNS2 and Foxp3 promoter. Our findings demonstrated an essential role for CNS2 in maintaining the stability and function of activated Treg cells and identified NFAT as a key mediator of its function.
Project description:T-regulatory (Treg) cells are important to immune homeostasis, and Treg cell deficiency or dysfunction leads to autoimmune disease. An histone/protein acetyltransferase (HAT), p300, was recently found important for Treg function and stability, but further insights into the mechanisms by which p300 or other HATs affect Treg biology are needed. Here we show that CBP, a p300 paralog, is also important in controlling Treg function and stability. Thus, while mice with Treg-specific deletion of CBP or p300 developed minimal autoimmune disease, the combined deletion of CBP and p300 led to fatal autoimmunity by 3-4 weeks of age. The effects of CBP and p300 deletion on Treg development are dose-dependent, and involve multiple mechanisms. CBP and p300 cooperate with several key Treg transcription factors that act on the Foxp3 promoter to promote Foxp3 production. CBP and p300 also act on the Foxp3 CNS2 region to maintain Treg stability in inflammatory environments by regulating pCREB function and GATA3 expression, respectively. Lastly, CBP and p300 regulate the epigenetic status and function of Foxp3. Our findings provide insights into how HATs orchestrate multiple aspects of Treg development and function, and identify overlapping but also discrete activities for p300 and CBP in control of Treg cells. RNA from three independent samples from magnetically separated CD4+CD25+ Treg of fl-p300/Foxp3cre mice and fl-CBP/Foxp3cre, compared to wild type (Foxp3cre) control (all C57Bl/6 background).
Project description:Thymus-originated tTregs and in vitro induced iTregs are subsets of regulatory T cells. While they share the capacity of immune suppression, their stabilities are different, with iTregs losing their phenotype upon stimulation or under inflammatory milieu. Epigenetic differences, particularly methylation state of Foxp3 CNS2 region, provide an explanation for this shift. Whether additional regulations, including cellular signaling, could directly lead phenotypical instability requires further analysis. Here we show that upon TCR triggering, store-operated calcium entry (SOCE) and NFAT nuclear translocation are blunted in tTregs, yet fully operational in iTregs, similar to Tconvs. On the other hand, tTregs show minimal changes in their chromatin accessibility upon activation, in contrast to iTregs that demonstrate an activated chromatin state with highly accessible T cell activation and inflammation related genes. Assisted by several cofactors, NFAT driven by strong SOCE signaling in iTregs preferentially binds to primed opened T helper (TH) genes, resulting in their activation normally observed only in Tconv activation, ultimately leads to instability. Conversely, suppression of SOCE in iTregs can partially rescue their phenotype. Thus our study adds two new layer, cellular signaling and chromatin accessibility, of understanding in Treg stability, and may provide a path for better clinical applications of Treg cell therapy.
Project description:Foxp3+ regulatory T (Treg) cells restrict immune pathology in inflamed tissues; however, an inflammatory environment presents a threat to Treg cell identity and function. We here establish a transcriptional signature of central nervous system (CNS) Treg cells that accumulate during experimental autoimmune encephalitis (EAE) and identify a pathway that maintains Treg cell function and identity during severe inflammation. This pathway was dependent on the transcriptional regulator Blimp1, which prevented dismantling of Foxp3 expression and "toxic" gain-of-function of Treg cells in the inflamed CNS. Blimp1 negatively regulated IL-6- and STAT3-mediated methylation of Treg cell-specific conserved non-coding sequence 2 (CNS2) in the Foxp3 locus. Consequently, CNS2 was heavily methylated when Blimp1 was ablated, leading to loss of Foxp3 expression and severe disease. These findings identify a Blimp1-dependent epigenetic pathway that preserves Treg cell stability in inflamed non-lymphoid tissues.
Project description:T-regulatory (Treg) cells are important to immune homeostasis, and Treg cell deficiency or dysfunction leads to autoimmune disease. An histone/protein acetyltransferase (HAT), p300, was recently found important for Treg function and stability, but further insights into the mechanisms by which p300 or other HATs affect Treg biology are needed. Here we show that CBP, a p300 paralog, is also important in controlling Treg function and stability. Thus, while mice with Treg-specific deletion of CBP or p300 developed minimal autoimmune disease, the combined deletion of CBP and p300 led to fatal autoimmunity by 3-4 weeks of age. The effects of CBP and p300 deletion on Treg development are dose-dependent, and involve multiple mechanisms. CBP and p300 cooperate with several key Treg transcription factors that act on the Foxp3 promoter to promote Foxp3 production. CBP and p300 also act on the Foxp3 CNS2 region to maintain Treg stability in inflammatory environments by regulating pCREB function and GATA3 expression, respectively. Lastly, CBP and p300 regulate the epigenetic status and function of Foxp3. Our findings provide insights into how HATs orchestrate multiple aspects of Treg development and function, and identify overlapping but also discrete activities for p300 and CBP in control of Treg cells.