Project description:Regulatory T cells (Tregs), lymphocytes that suppress immunological reactions, are of great interest for our comprehension of homeostasis and regulation in the immune system and as a therapeutic target in the treatment of both immune-mediated pathologies and reactivation of the immune response in patients with cancer. Understanding the molecular mechanisms by which these cells are regulated in respone to their environment will help to inform clinical strategies targeting Tregs. We hypothesised that Neuropilin-1, a transmembrane co-receptor for ligands of the semaphorin and growth factor families, promotes the suppressive function of human Tregs. Utilising in vitro lentivirus-mediated transduction with shRNA to knock down neuropilin-1 in primary human Tregs, we demonstrated that neuropilin-1 knockdown Tregs were severely impaired in their capacity to suppress cell proliferation in vitro and in their ability to prolong allograft survival in a humanised mouse model of transplantation. While neuropilin-1-KD Tregs exhibited no defects in survival, proliferation and activation upon stimulation in vitro, we hypothesised that loss of NRP1 expression would alter the global gene expression profile of human Tregs, revealing a NRP1-dependent Treg-associated transcriptional signature.
Project description:To investigate the function of Neuropilin-1 (NRP-1) in Foxp3+ regulatory T (Treg) cell stability and function, we cultured naïve CD4+ T cells under induced Treg cell (iTreg)-differentiating condition. We then flow sorted NRP-1+ and NRP-1- iTreg cells and performed gene expression profiling analysis.
Project description:Regulatory T cells (Treg cells), a distinct subset of CD4+ T cells, are necessary for the maintenance of immune self-tolerance and homeostasis. Recent studies have demonstrated that Treg cells display a unique metabolic profile characterized by an increase in mitochondrial metabolism relative to other CD4+ effector subsets. Furthermore, the Treg cell lineage-defining transcription factor, Foxp3, has been shown to promote respiration; however, it remains unknown whether the mitochondrial respiratory chain is required for Treg cell suppressive capacity, stability, and survival. Here we report that Treg cell-specific ablation of mitochondrial respiratory chain complex III results in the development of a fatal inflammatory disease early in life, without impacting Treg cell number. Mice lacking complex III specifically in Treg cells displayed a loss of Treg cell suppressive capacity without altering Treg cell proliferation and survival. Treg cells deficient in complex III display decreased expression of genes associated with Treg function while maintaining stable FOXP3 expression. Complex III-null Treg cells displayed increased DNA methylation at the loci of differentially down-regulated genes without a global increase in DNA methylation. Loss of complex III in Treg cells resulted in buildup of the metabolites 2-hydroxyglutarate (2-HG) and succinate that can function as inhibitors of α-ketoglutarate (α−KG)-dependent dioxygenase reactions such as the ten-eleven translocation (TET) family of DNA demethylases. Thus, Treg cells require mitochondrial respiration to maintain immune regulatory gene expression and suppressive function.
Project description:Regulatory T cells (Tregs) can suppress a wide variety of cell types, in diverse organ sites and inflammatory conditions. While Tregs possess multiple suppressive mechanisms, the number required for maximal function is unclear. Furthermore, whether any inter-relationship orcross-regulatory mechanisms exist that areused to orchestrate and control their utilization is unknown. Here we assessed the functional capacity of Tregs lacking the ability to secrete both interleukin-10 (IL-10) and IL-35, which individually are required for maximal Treg activity. Surprisingly, IL-10/IL-35-double deficient Tregswere fully functionalin vitro and in vivo. Loss of IL-10 and IL-35 was compensated for by a concurrent increase in cathepsin E (CTSE) expression, enhanced TRAIL (Tnfsf10)expression and soluble TRAIL release, rendering IL-10/IL-35-double deficient Tregsfunctionally dependent on TRAIL in vitro and in vivo. Lastly, while C57BL/6 Tregs are IL-10/IL-35-dependent, Balb/c Tregs, which express high levels of CTSE and enhanced TRAIL expression, are TRAIL-dependent.These data reveal that cross-regulatory pathways exist, which control the utilization of suppressive mechanisms,thereby providing Tregfunctional plasticity. Isolate natural Tregs from the different knockout mouse
Project description:Regulatory T cells (Treg cells), a distinct subset of CD4+ T cells, are necessary for the maintenance of immune self-tolerance and homeostasis. Recent studies have demonstrated that Treg cells display a unique metabolic profile characterized by an increase in mitochondrial metabolism relative to other CD4+ effector subsets. Furthermore, the Treg cell lineage-defining transcription factor, Foxp3, has been shown to promote respiration; however, it remains unknown whether the mitochondrial respiratory chain is required for Treg cell suppressive capacity, stability, and survival. Here we report that Treg cell-specific ablation of mitochondrial respiratory chain complex III results in the development of a fatal inflammatory disease early in life, without impacting Treg cell number. Mice lacking complex III specifically in Treg cells displayed a loss of Treg cell suppressive capacity without altering Treg cell proliferation and survival. Treg cells deficient in complex III display decreased expression of genes associated with Treg function while maintaining stable FOXP3 expression. Complex III-null Treg cells displayed increased DNA methylation at the loci of differentially down-regulated genes without a global increase in DNA methylation. Loss of complex III in Treg cells resulted in buildup of the metabolites 2-hydroxyglutarate (2-HG) and succinate that can function as inhibitors of α-ketoglutarate (α−KG)-dependent dioxygenase reactions such as the ten-eleven translocation (TET) family of DNA demethylases. Thus, Treg cells require mitochondrial respiration to maintain immune regulatory gene expression and suppressive function.
Project description:Regulatory T (Treg) cells play central roles in maintaining immune homeostasis and self-tolerance. However, the molecular mechanisms underlying Treg cell homeostasis and suppressive function are still not fully understood. Here, we report that the deletion of another P subfamily members of the forkhead box (Foxp) subfamily member Foxp1 in Treg cells led to increased numbers of activated Treg (aTreg) cells at the expense of quiescent Treg cells, and also resulted in impaired Treg suppressive function. Mice with Foxp1-deficient Treg cells developed spontaneous inflammatory disease with age; they also had more severe inflammatory disease in colitis and experimental autoimmune encephalomyelitis (EAE) models. Mechanistically, we found that Foxp1 bound to the conserved noncoding sequence 2 (CNS2) element of the Foxp3 locus and helped maintain Treg suppressive function by stabilizing the Foxp3 expression. Furthermore, we found that Foxp1 and Foxp3 coordinated the regulation of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) expression levels. Taken together, our study demonstrates that Foxp1 plays critical roles in both maintaining Treg cell quiescence during homeostasis and regulating Treg suppressive function.