Browsing publications of the research group experimentelle Immunologie (EXIM) by Subject (MeSH)
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Epigenetic modification of the human CCR6 gene is associated with stable CCR6 expression in T cells.CCR6 is a chemokine receptor expressed on Th17 cells and regulatory T cells that is induced by T-cell priming with certain cytokines, but how its expression and stability are regulated at the molecular level is largely unknown. Here, we identified and characterized a noncoding region of the human CCR6 locus that displayed unmethylated CpG motifs (differentially methylated region [DMR]) selectively in CCR6(+) lymphocytes. CCR6 expression on circulating CD4(+) T cells was stable on cytokine-induced proliferation but partially down-regulated on T-cell receptor stimulation. However, CCR6 down-regulation was mostly transient, and the DMR within the CCR6 locus remained demethylated. Notably, in vitro induction of CCR6 expression with cytokines in T-cell receptor-activated naive CD4(+) T cells was not associated with a demethylated DMR and resulted in unstable CCR6 expression. Conversely, treatment with the DNA methylation inhibitor 5'-azacytidine induced demethylation of the DMR and led to increased and stable CCR6 expression. Finally, when cloned into a reporter gene plasmid, the DMR displayed transcriptional activity in memory T cells that was suppressed by DNA methylation. In summary, we have identified a noncoding region of the human CCR6 gene with methylation-sensitive transcriptional activity in CCR6(+) T cells that controls stable CCR6 expression via epigenetic mechanisms.
Inhibition of the JAK/STAT Signaling Pathway in Regulatory T Cells Reveals a Very Dynamic Regulation of Foxp3 Expression.The IL-2/JAK3/STAT-5 signaling pathway is involved on the initiation and maintenance of the transcription factor Foxp3 in regulatory T cells (Treg) and has been associated with demethylation of the intronic Conserved Non Coding Sequence-2 (CNS2). However, the role of the JAK/STAT pathway in controlling Foxp3 in the short term has been poorly investigated. Using two different JAK/STAT pharmacological inhibitors, we observed a detectable loss of Foxp3 after 10 min. of treatment that affected 70% of the cells after one hour. Using cycloheximide, a general inhibitor of mRNA translation, we determined that Foxp3, but not CD25, has a high turnover in IL-2 stimulated Treg. This reduction was correlated with a rapid reduction of Foxp3 mRNA. This loss of Foxp3 was associated with a loss in STAT-5 binding to the CNS2, which however remains demethylated. Consequently, Foxp3 expression returns to normal level upon restoration of basal JAK/STAT signaling in vivo. Reduced expression of several genes defining Treg identity was also observed upon treatment. Thus, our results demonstrate that Foxp3 has a rapid turn over in Treg partly controlled at the transcriptional level by the JAK/STAT pathway.
Neuropilin 1 is expressed on thymus-derived natural regulatory T cells, but not mucosa-generated induced Foxp3+ T reg cells.Foxp3 activity is essential for the normal function of the immune system. Two types of regulatory T (T reg) cells express Foxp3, thymus-generated natural T reg (nT reg) cells, and peripherally generated adaptive T reg (iT reg) cells. These cell types have complementary functions. Until now, it has not been possible to distinguish iT reg from nT reg cells in vivo based solely on surface markers. We report here that Neuropilin 1 (Nrp1) is expressed at high levels by most nT reg cells; in contrast, mucosa-generated iT reg and other noninflammatory iT reg cells express low levels of Nrp1. We found that Nrp1 expression is under the control of TGF-β. By tracing nT reg and iT reg cells, we could establish that some tumors have a very large proportion of infiltrating iT reg cells. iT reg cells obtained from highly inflammatory environments, such as the spinal cords of mice with spontaneous autoimmune encephalomyelitis (EAE) and the lungs of mice with chronic asthma, express Nrp1. In the same animals, iT reg cells in secondary lymphoid organs remain Nrp1(low). We also determined that, in spontaneous EAE, iT reg cells help to establish a chronic phase of the disease.
The Treg-specific demethylated region stabilizes Foxp3 expression independently of NF-κB signaling.Regulatory T cells (Tregs) obtain immunosuppressive capacity by the upregulation of forkhead box protein 3 (Foxp3), and persistent expression of this transcription factor is required to maintain their immune regulatory function and ensure immune homeostasis. Stable Foxp3 expression is achieved through epigenetic modification of the Treg-specific demethylated region (TSDR), an evolutionarily conserved non-coding element within the Foxp3 gene locus. Here, we present molecular data suggesting that TSDR enhancer activity is restricted to T cells and cannot be induced in other immune cells such as macrophages or B cells. Since NF-κB signaling has been reported to be instrumental to induce Foxp3 expression during Treg development, we analyzed how NF-κB factors are involved in the molecular regulation of the TSDR. Unexpectedly, we neither observed transcriptional activity of a previously postulated NF-κB binding site within the TSDR nor did the entire TSDR show any transcriptional responsiveness to NF-κB activation at all. Finally, the NF-κB subunit c-Rel revealed to be dispensable for epigenetic imprinting of sustained Foxp3 expression by TSDR demethylation. In conclusion, we show that NF-κB signaling is not substantially involved in TSDR-mediated stabilization of Foxp3 expression in Tregs.