Project description:The CD4+Foxp3+ regulatory T cells play an essential role in maintaining tolerance via their suppressive function on conventional T cells. The intracellular signaling pathways that regulate Foxp3 expression are largely unknown. In this study we describe a novel inhibitory role for AKT in regulating de novo induction of Foxp3 both in vivo and in vitro. A constitutively active allele of AKT significantly diminished TGF-â induced Foxp3 induction via a rapamycin-sensitive pathway, establishing a role for the AKT-mTOR axis in Treg cells. Moreover, the observed impairment in Foxp3 induction was paralleled by a selective downmodulation of the imparted Treg transcriptional signature highlighting the importance of the balance of intracellular signals in Treg differentiation . Our results provide a basis for further elucidation of molecular mechanisms that regulate Foxp3 induction and identify AKT as an important negative regulator of this process. Experiment Overall Design: All gene expression profiles were obtained from highly purified T cell populations sorted by flow cytometry. To reduce variability, cells from multiple mice were pooled for sorting, and three replicates were generated for all groups. RNA from 0.5-2.5 x 105 cells was amplified, labeled, and hybridized to Affymetrix M430v2 microarrays. Raw data were preprocessed with the RMA algorithm in GenePattern, and averaged expression values were used for analysis.
Project description:The CD4+Foxp3+ regulatory T cells play an essential role in maintaining tolerance via their suppressive function on conventional T cells. The intracellular signaling pathways that regulate Foxp3 expression are largely unknown. In this study we describe a novel inhibitory role for AKT in regulating de novo induction of Foxp3 both in vivo and in vitro. A constitutively active allele of AKT significantly diminished TGF-â induced Foxp3 induction via a rapamycin-sensitive pathway, establishing a role for the AKT-mTOR axis in Treg cells. Moreover, the observed impairment in Foxp3 induction was paralleled by a selective downmodulation of the imparted Treg transcriptional signature highlighting the importance of the balance of intracellular signals in Treg differentiation . Our results provide a basis for further elucidation of molecular mechanisms that regulate Foxp3 induction and identify AKT as an important negative regulator of this process. Keywords: Cell population comparison
Project description:Mesenteric lymph node stromal cell-derived extracellular vesicles contribute to peripheral de novo induction of Foxp3+ regulatory T cells.
Project description:Intestinal Foxp3+ regulatory T cell (Treg) subsets are crucial players for tolerance towards microbiota-derived and food-borne antigens, and compelling evidence suggests that intestinal microbiota modulate their differentiation and maintenance. Selected bacterial species and microbiota-derived metabolites such as short-chain fatty acids (SCFAs) have been reported to foster Treg homeostasis in the intestinal lamina propria. Furthermore, gut-draining mesenteric lymph nodes (mLNs) are particularly efficient sites of de novo Treg induction, and we could previously show that mLN stromal cells contribute to this process. Yet, it is not fully elucidated which direct role microbiota and their metabolites play for the early stages of de novo Treg induction and in shaping the Treg transcriptome already during the initial priming within mLNs. Here, we show that neither dysbiotic microbiota nor dietary SCFA supplementation impact de novo induction of Foxp3+ Tregs within mLNs. Even mice housed under germ-free (GF) conditions displayed equivalent frequencies of de novo induced Foxp3+ Tregs within mLNs. Further dissection of the accessible chromatin and transcriptome revealed that microbiota indeed have a limited impact on fostering the establishment of peripherally induced Tregs and do not contribute to the initialization of the epigenetic landscape for an extensive Treg signature. Viewed as a whole, our data suggest that microbiota are dispensable for the early stages of de novo Treg induction within mLNs, while being required to foster further Treg differentiation and homeostasis at later stages within the intestinal lamina propria.
Project description:CD4+ regulatory T cells (Tregs) are key mediators of immunological tolerance and promising effector cells for immuno-suppressive adoptive cellular therapy to fight autoimmunity and chronic inflammation. Their functional stability is critical for their clinical utility and has been correlated to the demethylated state of the TSDR/CNS2 enhancer element in the Treg lineage transcription factor FOXP3. However, proof for a causal contribution of the TSDR de-methylation to FOXP3 stability and Treg induction is so far lacking. We here established a powerful transient-transfection CRISPR-Cas9-based epigenetic-editing method for the selective de-methylation of the TSDR within the endogenous chromatin environment of a living cell. The induced de-methylated state was stable over weeks in clonal T cell proliferation cultures even after expression of the editing complex had ceased. Epigenetic editing of the TSDR resulted in FOXP3 expression, even in its physiological isoform distribution, proving a causal role for the de-methylated TSDR in FOXP3 regulation. However, successful FOXP3 induction was not associated with a switch towards a functional Treg phenotype, in contrast to what has been reported from FOXP3 overexpression approaches. Thus, TSDR de-methylation is required, but not sufficient for a stable Treg phenotype induction. Therefore, targeted demethylation of the TSDR may be a critical addition to published in vitro Treg induction protocols which so far lack FOXP3 stability.