Project description:Transcriptional profiling shows that Treg in venous thrombi take on a repair Treg profile and produce the matricellular protein SPARC
Project description:The cells and mechanisms involved in blood clot resorption are only partially known. Regulatory T cells (Treg) accumulate in venous blood clots and regulate thrombolysis by controlling the recruitment, differentiation and matrix metalloproteinase (MMP) activity of monocytes. The clot Treg population is heterogeneous and contains a population of Treg that forms the matricellular acid- and cysteine-rich protein (SPARC). SPARC induces MMP activity in monocytes and SPARC+ Treg are required for clot resorption.
Project description:The inflammasome initiates innate defense and inflammatory response by activating caspase-1 and pyroptotic cell death in myeloid cells1,2. It is comprised of an innate immune receptor/effector, pro-caspase-1 and a common adaptor molecule, ASC (apoptotic speck-containing protein with a CARD). Consistent with their pro-inflammatory function, inflammasome components including caspase-1, ASC and NLRP3, are known to exacerbate autoimmunity during experimental autoimmune encephalomyelitis (EAE) by enhancing IL-1 and IL-18 secretion in myeloid cells3-6. Here we show an unexpected function of a DNA-binding inflammasome effector, AIM2 (Absent in Melanoma 2)7-10, in restraining autoimmunity by performing EAE in both whole body and Treg-specific deletion of Aim2–/– mice. AIM2 is highly expressed by human and mouse Treg cells and it is essential to attenuate EAE. RNA-seq, biochemical and metabolic analyses revealed that AIM2 attenuates mTOR, Myc and immune-metabolic functions in both Treg cells isolated in vivo and Treg cells induced in vitro with TGF-. Importantly, we found AIM2 physically interacted with RACK1 in Treg cells to facility the PP2A/RACK1/Akt-mTOR signaling, which is identified as a central component downstream of AIM2 that controls Treg cell function and stability. While AIM2 is generally accepted as an inflammasome effector in myeloid cells, this report reveals a previously unappreciated T cell-intrinsic role of AIM2 in maintaining Treg cell function to restrain autoimmunity. This is achieved by diminishing Akt-mTOR signaling to regulate Treg stability under inflammation, and altering immune-metabolism in Treg cells.
Project description:Thymic-derived natural T regulatory cells (nTregs) are characterized by functional and phenotypic heterogeneity. Recently, a small fraction of peripheral Tregs have been shown to express Klrg1, but it remains unclear the extent Klrg1 defines a unique Treg subset. Here we show that Klrg1+ Tregs represent a terminally differentiated Treg subset derived from Klrg1- Tregs. This subset is a recent antigen-responsive and a highly activated short-lived Treg population that expresses enhanced levels of Treg suppressive molecules and that preferentially resides within mucosal tissues. The development of Klrg1+ Tregs also requires extensive IL-2R signaling. This activity represents a distinct function for IL-2, independent from its contribution to Treg homeostasis and competitive fitness. These and other properties are analogous to terminally differentiated short-lived CD8+ T effector cells. Our findings suggest that an important pathway driving antigen-activated conventional T lymphocytes also operates for Tregs. Gene expression analysis was performed of this and other Treg subsets based on expression of CD62L, CD69, and Klrg1 to define the molecular properties of Klrg1+ Tregs and its relationship to other Treg subsets found in the peripheral immune tissues. Mice were euthanized, spleen cell preparations were made, and each Treg subset was isolated by FACS cell sorting. RNA was immediately prepared for processing.
Project description:Regulatory T (Treg) cells play an important role in the induction and maintenance of peripheral tolerance. Treg cells also suppress a variety of other immune responses, including anti-tumor and alloimmune responses. We have previously reported that tumor-activated Treg cells express granzyme B and that granzyme B is important for Treg cell-mediated suppression of anti-tumor immune responses (GSE13409). Here, we report that allogeneic mismatch also induces the expression of granzyme B. Granzyme B-deficient mice challenged with fully mismatched allogeneic P815 mastocytoma cells have markedly improved survival compared to WT and other granzyme- or perforin-deficient mice, suggesting an immunoregulatory role for granzyme B in this setting. Treg cells harvested from the tumor environment of P815-challenged mice express granzyme B. Treg cells also express granzyme B in vitro during mixed lymphocyte reactions and in vivo in a mouse model of graft-versus-host disease (GVHD). However, in contrast to findings from our previously published tumor model, granzyme B is not required for the suppression of effector T cell (Teff) proliferation in in vitro Treg suppression assays stimulated by either Concanavalin A or allogeneic antigen presenting cells. Additionally, in an ex vivo assay, sort-purified in vivo-activated CD4+Foxp3+ Treg cells from mice with active GVHD -- under conditions known to induce granzyme B expression in Treg cells -- suppressed Teff cell proliferation in a granzyme B-independent manner. Adoptive transfer of naive granzyme B-deficient CD4+CD25+ Treg cells into a mouse model of GVHD rescued hosts from lethatlity equivalently to naive wild-type Treg cells. Serum analysis of GVHD-associated cytokine production in these recipients also demonstrated that Treg cells suppressed production of IL-2, IL-4, IL-5, GM-CSF, and IFN-gamma in a granzyme B-independent manner. In order to determine whether the context in which Treg cells are activated alters the intrinsic properties of Treg cells, we used Foxp3 reporter mice to obtain gene expression profiles of CD4+Foxp3+ Treg cells purifed from naive resting spleens, spleens from mice with acute GVHD, and from ascites fluid of mice challenged intraperitoneally with allogeneic P815 tumor cells. Unsupervised analyses revealed distinct activation signatures of Treg cells among the 3 experimental groups. Taken together, these findings demonstrate that granzyme B is not required for Treg cell-mediated suppression of GVHD, which is in contrast to what we have previously reported for Treg cell function in the setting of tumor challenge. Cell intrinsic differences could partially account for these differential phenotypes. These data also suggest the therapeutic potential of targeting specific Treg cell suppressive functions in order to segregate GVHD and graft-versus-tumor effector functions. Experiment Overall Design: Six replicates of Naive CD4+Foxp3+ Treg cells were purified from resting spleens, five replicates of allogeneic tumor-activated Treg cells and three samples of GVHD-activated Treg cells. Experiment Overall Design: Naive reps 1-3 are controls for the GVHD-activated samples. Experiment Overall Design: Naive reps 4-6 are controls for the Allogeneic tumor-activated samples.
Project description:Regulatory T (Treg) cells, as central mediators of immune suppression, play crucial roles in many aspects of immune system physiology and pathophysiology. Treg cells are characterized by a distinct pattern of gene expression, including upregulation of immune-suppressive genes and silencing of inflammatory cytokine genes. However, the molecular mechanisms that establish and/or maintain such gene regulation in Treg cells remain largely unknown. We recently reported that Nr4a family nuclear orphan receptors are essential for the development of Treg cells. The fact that Treg cells maintain high levels of expression of all Nr4a family components suggests that they may also play critical roles beyond Treg cell development. Thus, we compared mRNA expression pattern between wild-type Treg cells and Nr4a-deficietn Treg cells. As a result, we found that expression of 'Treg-signature genes' were globally down regulated in Nr4a-deficient Treg cells. mRNA from wild-type and Nr4a-deficient Treg cells were analyzed.
Project description:T regulatory lymphocytes were shown to be partly responsible for immune tolerance to cancer cells. In that respect these cells oppose to the mounting of an efficacious immune response needed to cure cancer. To treat advanced metastatic colorectal cancer, the investigators propose an immunotherapy consisting in autologous lymphocytes infusion depleted from T-regulatory cells, associated with a 5-day prior lymphoid-ablative chemotherapy associating cyclophosphamide (day 1 & 2) with fludarabine (day 1 to 5). To administer treatment and monitor chemotherapy safety, patients will be hospitalized for 3 weeks until complete recovery from chemotherapy. Patients will then be followed-up ambulatory for 9 months during which time they will be assessed for tumor size with computed tomography (CT) - scan (primary criteria).
Project description:Thymic-derived natural T regulatory cells (nTregs) are characterized by functional and phenotypic heterogeneity. Recently, a small fraction of peripheral Tregs have been shown to express Klrg1, but it remains unclear the extent Klrg1 defines a unique Treg subset. Here we show that Klrg1+ Tregs represent a terminally differentiated Treg subset derived from Klrg1- Tregs. This subset is a recent antigen-responsive and a highly activated short-lived Treg population that expresses enhanced levels of Treg suppressive molecules and that preferentially resides within mucosal tissues. The development of Klrg1+ Tregs also requires extensive IL-2R signaling. This activity represents a distinct function for IL-2, independent from its contribution to Treg homeostasis and competitive fitness. These and other properties are analogous to terminally differentiated short-lived CD8+ T effector cells. Our findings suggest that an important pathway driving antigen-activated conventional T lymphocytes also operates for Tregs. Gene expression analysis was performed of this and other Treg subsets based on expression of CD62L, CD69, and Klrg1 to define the molecular properties of Klrg1+ Tregs and its relationship to other Treg subsets found in the peripheral immune tissues.