Dataset Information

Transcriptional regulation of FOXP3 requires integrated activation of both promoter and CNS regions in tumor-induced CD8+ Treg cells.

ABSTRACT: T-regulatory cells are an upsurge in the tumor microenvironment and induce immune-evasion. CD4+ Treg cells are well characterized whereas the role of CD8+ Tregs in cancer has recently started to crease attention. Here, we report an augmentation CD8+FOXP3+ Tregs in breast tumor microenvironment. FOXP3, the lineage-specific transcription factor, is a dominant regulator of Treg cell development and function. FOXP3 is induced preferentially by divergent signaling in CD4+ Treg cells. But how FOXP3 is induced and maintained in tumor-CD8+ Tregs is the Cinderella of the investigation. We observed that RUNX3, a CD8+ lineage-specific transcription factor, binds at the FOXP3-promoter to induce its transcription. In addition to promoter activation, involvement of cis-elements CNS1 and CNS2 in the transcriptional regulation of FOXP3 was also evident in these cells. SMAD3 binds to CNS1 region and acts as transcription inducer, whereas GATA3 plays a temporal role in the FOXP3 transcription by differential chromatin modification in CNS regions. In CNS1 region, GATA3 acts as a repressor for FOXP3 in naïve CD8+ T cells. Whereas in CD8+ Tregs, GATA3 binds directly at CNS2 region and persuaded the maintenance of FOXP3. Therefore, the intervention of these concerted transcriptional machinery may have a therapeutic potential in immunotherapy of cancer.

SUBMITTER: Chakraborty S

PROVIDER: S-EPMC5431671 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Transcriptional regulation of FOXP3 requires integrated activation of both promoter and CNS regions in tumor-induced CD8+ Treg cells.

Chakraborty Sreeparna S Panda Abir K AK Bose Sayantan S Roy Dia D Kajal Kirti K Guha Deblina D Sa Gaurisankar G

Scientific reports 20170509 1

T-regulatory cells are an upsurge in the tumor microenvironment and induce immune-evasion. CD4+ Treg cells are well characterized whereas the role of CD8+ Tregs in cancer has recently started to crease attention. Here, we report an augmentation CD8+FOXP3+ Tregs in breast tumor microenvironment. FOXP3, the lineage-specific transcription factor, is a dominant regulator of Treg cell development and function. FOXP3 is induced preferentially by divergent si ...[more]

PMID: 28487507

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Project description:BACKGROUND: Naturally occurring thymus derived regulatory T cells (Tregs) are central in the maintenance of self-tolerance. The transcription factor FOXP3 is crucial for the suppressive activity of Tregs and is considered the most specific marker for this population. However, human non regulatory T cells upregulate FOXP3 transiently upon activation which calls for other means to identify the Treg population. Since epigenetic mechanisms are involved in the establishment of stable gene expression patterns during cell differentiation, we hypothesized that the methylation profile of the FOXP3 promoter would allow the distinction of truly committed Tregs. METHODOLOGY/PRINCIPAL FINDINGS: Human CD4(+)CD25(hi) Tregs displayed a demethylated FOXP3 promoter (1.4%+/-0.95% SEM methylated) in contrast to CD4(+)CD25(lo) T cells which were partially methylated (27.9%+/-7.1%). Furthermore, stimulated CD4(+)CD25(lo) T cells transiently expressed FOXP3 but remained partially methylated, suggesting promoter methylation as a mechanism for regulation of stable FOXP3 expression and Treg commitment. In addition, transient FOXP3 expressing cells exhibited suppressive abilities that correlate to the methylation status of the FOXP3 promoter. As an alternative to bisulphite sequencing, we present a restriction enzyme based screening method for the identification of committed Tregs and apply this method to evaluate the effect of various culturing conditions. We show that a partial demethylation occurs in long-term cultures after activation, whereas the addition of TGF-beta and/or IL-10 does not induce any additional change in methylation level. CONCLUSIONS/SIGNIFICANCE: The unique FOXP3 promoter methylation profile in Tregs suggests that a demethylated pattern is a prerequisite for stable FOXP3 expression and suppressive phenotype. Presently, FOXP3 is used to identify Tregs in several human diseases and there are future implications for adoptive Treg transfer in immunotherapy. In these settings there is a need to distinguish true Tregs from transiently FOXP3(+) activated T cells. The screening method we present allows this distinction and enables the identification of cells suitable for in vitro expansions and clinical use.

Project description:The continual rise of asthma in industrialised countries stands in strong contrast to the situation in developing lands. According to the modified Hygiene Hypothesis, helminths play a major role in suppressing bystander immune responses to allergens, and both epidemiological and experimental studies suggest that the tropical parasitic trematode Schistosoma mansoni elicits such effects. The focus of this study was to investigate which developmental stages of schistosome infection confer suppression of allergic airway inflammation (AAI) using ovalbumin (OVA) as a model allergen. Moreover, we assessed the functional role and localization of infection-induced CD4(+)Foxp3(+) regulatory T cells (Treg) in mediating such suppressive effects. Therefore, AAI was elicited using OVA/adjuvant sensitizations with subsequent OVA aerosolic challenge and was induced during various stages of infection, as well as after successful anti-helminthic treatment with praziquantel. The role of Treg was determined by specifically depleting Treg in a genetically modified mouse model (DEREG) during schistosome infection. Alterations in AAI were determined by cell infiltration levels into the bronchial system, OVA-specific IgE and Th2 type responses, airway hyper-sensitivity and lung pathology. Our results demonstrate that schistosome infection leads to a suppression of OVA-induced AAI when mice are challenged during the patent phase of infection: production of eggs by fecund female worms. Moreover, this ameliorating effect does not persist after anti-helminthic treatment, and depletion of Treg reverts suppression, resulting in aggravated AAI responses. This is most likely due to a delayed reconstitution of Treg in infected-depleted animals which have strong ongoing immune responses. In summary, we conclude that schistosome-mediated suppression of AAI requires the presence of viable eggs and infection-driven Treg cells. These data provide evidence that helminth derived products could be incorporated into treatment strategies that specifically target suppression of immune responses in AAI by inducing Treg cells.

Dataset Information

Transcriptional regulation of FOXP3 requires integrated activation of both promoter and CNS regions in tumor-induced CD8+ Treg cells.

Publications

Transcriptional regulation of FOXP3 requires integrated activation of both promoter and CNS regions in tumor-induced CD8<sup>+</sup> Treg cells.

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