The Glucose Transporter GLUT3 Controls Regulatory T Cell Function

Regulatory T Cells Stay on Course

Immune Derangements in Patients with Myelofibrosis- the Role of Treg, Th17, and sIL2α

Regulatory T (Treg) cells, a distinct lineage of T cells, are required to maintain immunological tolerance. However, the molecular mechanism(s) by which Treg cells modulate tumor growth and clearance needs further investigation. Thus, the goal of this study is to analyze the absolute number and role of Treg cells during tumorigenesis. To achieve this goal, tumor induction studies were performed on C57/B6 mice using transgenic adenocarcinoma mouse prostate (TRAMP) cell lines C1, C2 and C3. Interestingly, TRAMP C1 and C2 are tumorigenic while TRAMP C3 fail to form tumor. C57/B6 mice treated with different tumorigenic concentrations of TRAMP (C1, C2, and C3) cells. The experimental design also included appropriate controls. Developing tumors, spleen and draining lymph nodes were dissected out and single cell suspensions were prepared. Cells were stained with the specific antibodies such as NK cells, NKT cells, CD4, CD8, macrophages, B cells and Treg cells and analyzed using a 13-color flowcytometer. Preliminary data revealed that development of tumors by TRAMP C1 and TRAMP C2 cells and non-tumorigenesis by TRAMP C3 cells was dependent on number of Treg cells in tumor microenvironment. Therefore, the data suggest that the number of Treg cells present in tumor microenvironment may have a direct impact on tumor progression and clearance. Thus, modulating the number of Treg cells in tumor microenvironment may be a successful therapeutic strategy to control tumor progression

CD38 Expression Levels on Myeloma Cells and the Frequency of Circulating CD38-Positive Treg Cells Are Associated with the Response to Daratumumab in Multiple Myeloma

ObjectiveRheumatoid arthritis (RA) is a typical, progressive autoimmune disease. Its occurrence and development are associated with dysregulation of T and B cell numbers. However, the specific immune characteristics of different RA courses remain incompletely defined. Here, we describe the peripheral blood lymphocyte subsets, particularly CD4 + T subsets, of different RA courses with a focus on early RA (Ea-RA).MethodsIn all, 131 patients with Ea-RA, 117 with advanced RA (Ad-RA), and 109 with treated RA (Tr-RA) were enrolled. We collected general clinical data. Whole blood samples obtained from the patients and 97 healthy controls (HCs) were analysed via flow cytometry.ResultsDecreased absolute NK cell numbers and increased CD4/CD8 T cell ratios were observed in different RA groups, including Ea-RA, compared to healthy controls. In Ea-RA patients, the Th17 and Treg cell numbers were similar to those in HCs. We performed k-means clustering based on the profiles of Th17 and Treg cells for patients with multi-stage of RA. We identified three patient types: type A characterised by relatively low Treg and Th17 cell numbers, type B with moderate levels of Treg cells and levels of Th17 cells similar to that of type C patients, and type C with high levels of Treg cells and levels of Th17 cells similar to that of type B patients.ConclusionThe immune characteristics of Ea-RA patients differ from those of HCs; an immune system disorder is apparent although no differences in Th17 and Treg levels were evident between Ea-RA patients and HCs. We found distributional heterogeneities of Th17 and Treg cells in patients with multi-stage of RA. Stratified management based on such heterogeneity may serve as a useful novel immunotherapy allowing of early intervention.

Naturally occurring regulatory T (Treg) cells, which express the transcription factor Foxp3, are indispensable for immunological self-tolerance and immune homeostasis. They also hinder effective tumor immunity and can therefore be targeted to evoke anti-tumor immune responses by reducing them or attenuating their suppressive activity (1). Human Foxp3+ T cells are heterogenous in function and phenotype, including suppressive and non-suppressive populations (2, 3). Efforts to delineate these populations have shown that Foxp3+ cells in the peripheral blood can be separated into at least three functionally distinct subpopulations, including (i) highly proliferative and differentiated Foxp3-high population (designated effector Treg cells) with stable Treg-specific epigenome alterations, the majority of which will die by apoptosis after suppression, (ii) naïve Foxp3-low population (naïve Treg cells), which is in a resting state and upon TCR stimulation differentiates into effector Treg cells, and (iii) Foxp3-low non-suppressive population unstable in Treg-specific epigenome changes and capable of secreting pro-inflammatory cytokines. The three Foxp3+ T-cell subpopulations in the peripheral blood can be distinguished by a combination of expression levels of cell surface molecules such as CD45RA and CD15s (sialyl Lewis X); for example, effector Tregs are CD45RA−CD15s+; naïve Tregs CD45RA+CD15s−; non-Treg cells CD45RA−CD15s−. Each population exhibits distinct behavior in different disease states (2, 3). There is accumulating evidence that abundant Treg cell infiltration into tumors is associated with poor clinical outcomes in various types of cancers. However, the role of Treg cells is controversial in colorectal cancers (CRCs), in which FOXP3+ T cell infiltration indicates better prognosis in some studies. We have recently shown that CRCs, which are commonly infiltrated by terminally differentiated and suppression-competent FOXP3hi Treg cells, can be classified into two types by the degree of additional infiltration of FOXP3lo nonsuppressive T cells capable of secreting inflammatory cytokines (4). Interestingly, CRCs with abundant infiltration of the latter show significantly better prognosis than those with predominant FOXP3hi Treg cell infiltration. Development of such inflammatory FOXP3lo non-Treg cells appears to depend on secretion of IL-12 and TGF-β by tumor tissues and to be correlated with tumor invasion by intestinal bacteria, especially Fusobacterium nucleatum. Thus, functionally distinct subpopulations of tumor-infiltrating FOXP3+ T cells contribute in opposing ways to determining CRC prognosis. These results also indicate indicate that depletion of suppression-competent FOXP3hi effector Treg cells from tumor tissues is an effective treatment strategy for various cancers including CRC. Indeed, depletion of FOXP3hi effector Treg cells alone by administration of cell-depleting anti-CCR4 mAb is able to evoke effective tumor immunity without serious autoimmunity (5). Similarly, Imatinib, a tyrosine kinase inhibitor for the treatment of chronic myeloid leukemia, is able to evoke tumor immunity via specifically depleting effector Treg cells as an off target effect (unpublished). Taken together, Treg depletion by biologicals or small molecules, together with other treatments to activate effector T cells (e.g., tumor antigen vaccination or immune checkpoint blockade) can be an effective way of cancer immunotherapy.

Ripk1 plays an important role as a regulator of programmed cell death processes such as apoptosis and necroptosis and is involved in initiating pro-inflammatory NF-κB signaling. Immune tolerance depends on the proper function and homeostasis of regulatory T (Treg) cells. Here, we show that specific ablation of Ripk1 in Treg cells leads to systemically reduced Treg cell numbers resulting in spontaneous whole-body pathology. Using chimeric mice that allowed us to study Treg cells in the absence of inflammatory conditions, we observed a competitive disadvantage in vivo of Ripk1-deficient compared to Ripk1-proficient Treg cells. Furthermore, single-cell RNA sequencing revealed that Ripk1 is required for the maintenance of the effector Treg cell transcriptional signature, which is essential to prevent immune dysregulation. To overcome the limitation of low cell numbers in the chimeric mice, we isolated Treg cells from mice, in which Ripk1 could be deleted in a tamoxifen-inducible manner. Despite the strong reduction detected in Ripk1-deficient Treg cells of the chimeric mice, we did not observe impaired viability by the sole absence of Ripk1 in Treg cells from the inducible system. Of note, we observed reduced viability of activated Ripk1-deficient Treg cells in the presence of TNF. Together, these findings highlight the fundamental role of Ripk1 in maintaining immune homeostasis by preserving the highly suppressive effector Treg cells.

Lymphedema (LD) is characterized by the accumulation of interstitial fluid, lipids and inflammatory cell infiltrate in the limb. Here, we find that LD tissues from women who developed LD after breast cancer exhibit an inflamed gene expression profile. Lipidomic analysis reveals decrease in specialized pro-resolving mediators (SPM) generated by the 15-lipoxygenase (15-LO) in LD. In mice, the loss of SPM is associated with an increase in apoptotic regulatory T (Treg) cell number. In addition, the selective depletion of 15-LO in the lymphatic endothelium induces an aggravation of LD that can be rescued by Treg cell adoptive transfer or ALOX15-expressing lentivector injections. Mechanistically, exogenous injections of the pro-resolving cytokine IFN−β restores both 15-LO expression and Treg cell number in a mouse model of LD. These results provide evidence that lymphatic 15-LO may represent a therapeutic target for LD by serving as a mediator of Treg cell populations to resolve inflammation.

Rapamycin Promotes the Enrichment of CD4 +CD25 hiFoxP3 + T Regulatory Cells From Naïve CD4 + T Cells of Baboon That Suppress Antiporcine Xenogenic Response In Vitro

The predominance of Th17 lymphocytes and decreased number and function of Treg cells in preeclampsia

Regulatory T (Treg) cells are critical for immunological tolerance and immune homeostasis. Treg cells strongly rely on mitochondrial metabolism and show a lower level of glycolysis. However, little is known about the role of lipid metabolism in the regulation of Treg cell homeostasis. Some members of the ACSL family of acyl-coenzyme A (CoA) synthases are expressed in Tcells, but their function remains unclear. A combination of RNA-sequencing and proteome analyses shows that Acsbg1, a member of ACSL, is selectively expressed in Treg cells. We show that the genetic deletion of Acsbg1 not only causes mitochondrial dysfunction, but it also dampens other metabolic pathways. The extrinsic supplementation of Acsbg1-deficient Treg cells with oleoyl-CoA restores the phenotype of the Treg metabolic signature. Furthermore, this pathway in ST2+ effector Treg cells enhances immunosuppressive capacity in airway inflammation. Thus, Acsbg1 serves as a metabolic checkpoint governing Treg cell homeostasis and the resolution of lung inflammation.

Regulatory T (Treg) cells, which express Foxp3 as a transcription factor, are subsets of CD4(+) T cells. Treg cells play crucial roles in immune tolerance and homeostasis maintenance by regulating the immune response. The primary role of Treg cells is to suppress the proliferation of effector T (Teff) cells and the production of cytokines such as IFN-γ, TNF-α, and IL-2. It has been demonstrated that Treg cells' ability to inhibit the function of Teff cells is enhanced during persistent pathogen infection and cancer development. To clarify the function of Treg cells under resting or inflamed conditions, a variety of in vitro suppression assays using mouse or human Treg cells have been devised. The main aim of this study is to develop a method to compare the differences in phenotype and suppressive function between resting and activated Treg cells. To isolate activated Treg cells, mice were infected with lymphocytic choriomeningitis virus (LCMV) clone 13 (CL13), a chronic strain of LCMV. Treg cells isolated from the spleen of LCMV CL13-infected mice exhibited both the activated phenotype and enhanced suppressive activity compared with resting Treg cells isolated from naïve mice. Here, we describe the basic protocol for ex vivo phenotype analysis to distinguish activated Treg cells from resting Treg cells. Furthermore, we describe a protocol for the measurement of the suppressive activity of fully activated Treg cells.

Regulatory T (TReg) cells constitute an essential counterbalance to adaptive immune responses. Failure to maintain appropriate TReg cell numbers or function leads to autoimmune, malignant and immunodeficient conditions. Dynamic homeostatic processes preserve the number of forkhead box P3-expressing (FOXP3(+)) TReg cells within a healthy range, with high rates of cell division being offset by apoptosis under steady-state conditions. Recent studies have shown that TReg cells become specialized for different environmental contexts, tailoring their functions and homeostatic properties to a wide range of tissues and immune conditions. In this Review, we describe new insights into the molecular controls that maintain the steady-state homeostasis of TReg cells and the cues that drive TReg cell adaptation to inflammation and/or different locations. We highlight how differing local milieu might drive context-specific TReg cell function and restoration of immune homeostasis, and how dysregulation of these processes can precipitate disease.

Natural regulatory T cells in isolated early responders compared with dual responders with allergic asthma

Promising immunotherapeutic strategies are emerging to restore tolerance in autoimmune diseases by triggering an increase in the number and/or the function of endogenous regulatory T (Treg) cells, which actively control pathological immune responses. Evidence suggests a remarkable heterogeneity in peripheral Treg cells that warrants their better characterization in terms of phenotype and suppressive function, to determine which subset may be optimally suitable for a given clinical situation. We found that repetitive injections of immature dendritic cells expanded Foxp3-negative CD49b(+) Treg cells that displayed an effector memory phenotype. These expanded Treg cells were isolated ex vivo for transcriptome analysis and found to contain multiple transcripts of the canonical Treg signature shared mainly by CD25(+) but also by other subphenotypes. We characterized the CD49b(+) Treg cell phenotype, underscoring its similarities with the CD25(+) Treg cell phenotype and highlighting some differential expression patterns for several markers, including lymphocyte activation gene 3, KLRG1, CD103, ICOS, CTLA-4, and granzyme B. Comparison of the CD25(+) and CD49b(+) Treg cells' suppressive mechanisms, in vitro and in vivo, revealed the latter's potent suppressive activity, which was partly dependent on IL-10 secretion. Altogether, our results strongly suggest that expression of several canonical Treg cell markers and suppressive function could be Foxp3 independent, and underscore the therapeutic potential of IL-10-secreting CD49b(+) Treg cells in arthritis.