Effector Treg Cells Research Articles

Major depression favors the expansion of Th17-like cells and decrease the proportion of CD39+Treg cell subsets in response to myelin antigen in multiple sclerosis patients.

Mood disorders have been associated with risk of clinical relapses in multiple sclerosis (MS), a demyelinating disease mediated by myelin-specific T cells. We aimed to investigate the impact of major depressive disorder (MDD) and cytokine profile of T-cells in relapsing remitting MS patients. For our study, plasma and PBMC were obtained from 60 MS patients (30 with lifetime MDD) in remission phase. The PBMC cultures were stimulated with anti-CD3/anti-CD28 beads or myelin basic protein (MBP), and effector and regulatory T cell phenotypes were determined by flow cytometry. The cytokine levels, both in the plasma or in the supernatants collected from PBMC cultures, were quantified by Luminex. In some experiments, the effect of serotonin (5-HT) was investigated. Here, higher Th17-related cytokine levels in response to anti-CD3/anti-CD28 and MBP were quantified in the plasma and PBMC cultures of the MS/MDD group in comparison with MS patients. Further, elevated frequency of CD4+ and CD8+ T cells capable of producing IL-17, IL-22 and GM-CSF was observed in depressed patients. Interestingly, the percentage of myelin-specific IFN-γ+IL-17+ and IFN-γ+GM-CSF+ CD4+ T cells directly correlated with neurological disabilities. In contrast, the occurrence of MDD reduced the proportion of MBP-specific CD39+Tregs subsets. Notably, the severity of both neurological disorder and depressive symptoms inversely correlated with these Tregs. Finally, the addition of 5-HT downregulated the release of Th17-related cytokines in response to anti-CD3/anti-CD28 and myelin antigen. In summary, our findings suggested that recurrent major depression, by favoring imbalances of effector Th17 and Treg cell subsets, contributes to MS severity.

Dynamic transcriptional activity and chromatin remodeling of regulatory T cells after varied duration of interleukin-2 receptor signaling.

Regulatory T cells (Tregs) require (interleukin-2) IL-2 for their homeostasis by affecting their proliferation, survival, and activation. Here we investigated transcriptional and epigenetic changes after acute, periodic, and persistent IL-2 receptor (IL-2R) signaling in murine peripheral Tregs in vivo using IL-2 or the long-acting IL-2-based biologic mouse IL-2/CD25. We show that initially IL-2R-dependent STAT5 transcription factor-dependent pathways enhanced gene activation, chromatin accessibility, and metabolic reprogramming to support Treg proliferation. Unexpectedly, at peak proliferation, less accessible chromatin prevailed and was associated with Treg contraction. Restimulation of IL-2R signaling after contraction activated signature IL-2-dependent genes and others associated with effector Tregs, whereas genes associated with signal transduction were down-regulated to somewhat temper expansion. Thus, IL-2R-dependent Treg homeostasis depends in part on a shift from more accessible chromatin and expansion to less accessible chromatin and contraction. Mouse IL-2/CD25 supported greater expansion and a more extensive transcriptional state than IL-2 in Tregs, consistent with greater efficacy to control autoimmunity.

Selected Articles from This Issue

Well-differentiated liposarcoma (WDLPS) and dedifferentiated liposarcoma (DDLPS) are both characterized by amplification of MDM2 and CDK4. Although inhibitors of both MDM2 and CDK4 have shown clinical promise as monotherapy, preclinical studies have revealed synergy between MDM2 and CDK4 inhibitors. To assess this combination treatment strategy, Abdul Razak and colleagues conducted a clinical trial combining siremadlin, a p53–MDM2 inhibitor, with ribociclib, a CDK4/6 inhibitor, in patients with locally advanced/metastatic WDLPS or DDLPS. The toxicity profile of this combination was manageable. Furthermore, preliminary signs of clinical activity were observed, with 3 patients achieving a partial response and 38 achieving stable disease. These results suggest that the combination of siremadlin and ribociclib should be studied in future clinical trials.The process of autophagy has been shown to lead to resistance to BRAF/MEK inhibition in BRAFV600-mutant melanoma. To investigate whether this resistance mechanism can be circumvented, Mehnert and colleagues conducted a phase I/II clinical trial assessing the combination of hydroxychloroquine (HCQ), an autophagy inhibitor, with dabrafenib and trametinib, in patients with BRAFV600-mutant melanoma. This combination was well tolerated but did not meet a previously determined criteria for success. That said, evidence of clinical activity was observed: a complete response rate of 41% was observed across the entire cohort, while a response rate of 88% was observed in patients with elevated LDH. A follow-up clinical trial is underway to further study this combination in patients with LDH-elevated, BRAFV600-mutant melanoma.Ionizing radiation has been proposed to enhance the efficacy of checkpoint inhibitors. This combinatorial strategy has been shown to be effective in non-small cell lung cancer and other advanced cancer subtypes. To assess the efficacy of this strategy in patients locally advanced rectal cancer (LARC), Bando and colleagues conducted a phase I trial assessing chemotherapy followed by nivolumab and surgery. A pathological complete response (pCR) was observed in 30% and 60% of patients with MSS and MSI-H LARC, respectively. The authors observed elevated PD-L1 levels and CD8+/effector T-reg cell ratio in patients with pCR. Further clinical trials are needed to confirm these results and further establish prognostic biomarkers for this strategy.Tislelizumab is an anti-PD-1 monoclonal antibody specifically designed to minimize binding to Fcγ receptors (FcγR) and subsequent antibody-dependent phagocytosis by macrophages. Song and colleagues conducted an extended three-year follow-up of a phase II clinical trial of tislelizumab in patients with relapsed/refractor classical Hodgkin lymphoma. Tislelizumab remained generally well-tolerated over this extended period. The overall response rate was 87.1%, and the complete response rate was 67.1%, with 3-year progression-free and overall survival rates of 40.8% and 84.8, respectively. Interestingly, FcγRI-positive macrophages did not correlate with CR or PFS. These results are encouraging, warranting further clinical investigation of tislelizumab.

Laparoscopic sleeve gastrectomy for morbid obesity improves gut microbiota balance, increases colonic mucosal-associated invariant T cells and decreases circulating regulatory T cells.

Laparoscopic sleeve gastrectomy (LSG) for morbid obesity may improve gut microbiota balance and decrease chronic inflammation. This study examines the changes in gut microbiota and immune environment, including mucosal-associated invariant T cells (MAIT cells) and regulatory T cells (Treg cells) caused by LSG. Ten morbidly obese patients underwent LSG at our institution between December 2018 and March 2020. Flow cytometry for Th1/Th2/Th17 cells, Treg cells and MAIT cells in peripheral blood and colonic mucosa and 16S rRNA analysis of gut microbiota were performed preoperatively and then 12months postoperatively. Twelve months after LSG, the median percent total weight loss was 30.3% and the median percent excess weight loss was 66.9%. According to laboratory data, adiponectin increased, leptin decreased, and chronic inflammation improved after LSG. In the gut microbiota, Bacteroidetes and Fusobacteria increased after LSG, and indices of alpha diversity increased after LSG. In colonic mucosa, the frequency of MAIT cells increased after LSG. In peripheral blood, the frequency of Th1 cells and effector Treg cells decreased after LSG. After LSG for morbid obesity, improvement in chronic inflammation in obesity is suggested by change in the constituent bacterial species, increase in the diversity of gut microbiota, increase in MAIT cells in the colonic mucosa, and decrease in effector Treg cells in the peripheral blood.

Single-Cell Transcriptomics Reveals Discrete Steps in Regulatory T Cell Development in the Human Thymus.

CD4+CD25+FOXP3+ regulatory T (Treg) cells control immunological tolerance. Treg cells are generated in the thymus (tTreg) or in the periphery. Their superior lineage fidelity makes tTregs the preferred cell type for adoptive cell therapy (ACT). How human tTreg cells develop is incompletely understood. By combining single-cell transcriptomics and flow cytometry, we in this study delineated three major Treg developmental stages in the human thymus. At the first stage, which we propose to name pre-Treg I, cells still express lineage-inappropriate genes and exhibit signs of TCR signaling, presumably reflecting recognition of self-antigen. The subsequent pre-Treg II stage is marked by the sharp appearance of transcription factor FOXO1 and features induction of KLF2 and CCR7, in apparent preparation for thymic exit. The pre-Treg II stage can further be refined based on the sequential acquisition of surface markers CD31 and GPA33. The expression of CD45RA, finally, completes the phenotype also found on mature recent thymic emigrant Treg cells. Remarkably, the thymus contains a substantial fraction of recirculating mature effector Treg cells, distinguishable by expression of inflammatory chemokine receptors and absence of CCR7. The developmental origin of these cells is unclear and warrants caution when using thymic tissue as a source of stable cells for ACT. We show that cells in the major developmental stages can be distinguished using the surface markers CD1a, CD27, CCR7, and CD39, allowing for their viable isolation. These insights help identify fully mature tTreg cells for ACT and can serve as a basis for further mechanistic studies into tTreg development.

Depletion of central memory CD8+ T cells might impede the antitumor therapeutic effect of Mogamulizumab

Regulatory T (Treg) cells are important negative regulators of immune homeostasis, but in cancers they tone down the anti-tumor immune response. They are distinguished by high expression levels of the chemokine receptor CCR4, hence their targeting by the anti-CCR4 monoclonal antibody mogamulizumab holds therapeutic promise. Here we show that despite a significant reduction in peripheral effector Treg cells, clinical responses are minimal in a cohort of patients with advanced CCR4-negative solid cancer in a phase Ib study (NCT01929486). Comprehensive immune-monitoring reveals that the abundance of CCR4-expressing central memory CD8+ T cells that are known to play roles in the antitumor immune response is reduced. In long survivors, characterised by lower CCR4 expression in their central memory CD8+ T cells possessed and/or NK cells with an exhausted phenotype, cell numbers are eventually maintained. Our study thus shows that mogamulizumab doses that are currently administered to patients in clinical studies may not differentiate between targeting effector Treg cells and central memory CD8+ T cells, and dosage refinement might be necessary to avoid depletion of effector components during immune therapy.

Regulatory T Cell as a Biomarker of Treatment-Free Remission in Patients with Chronic Myeloid Leukemia.

Simple SummaryTyrosine kinase inhibitors (TKIs) have dramatically improved the treatment of chronic myeloid leukemia (CML). Recently, TKIs were discontinued in patients with CML with deep molecular remission, and some patients have been reported to be able to maintain long-term treatment-free remission (TFR). However, there is no certainty regarding which patients can maintain TFR. We focused on immunity in the TFR phase and investigated the immunological mechanism of continuous TFR or recurrence. Our results suggest that the group that maintains the TFR is immunologically activated. In addition, regulatory T cells can be used as a biomarker. These results may have important implications for future strategies for maintaining TFR in CML treatment. Treatment-free remission (TFR) has become a therapeutic goal in chronic myeloid leukemia (CML), and approximately half of the patients with chronic phase-CML (CML-CP) with deep molecular remission (DMR) by tyrosine-kinase inhibitors (TKIs) have achieved TFR. However, the mechanism of continuous TFR is still unclear, as there are “fluctuate” patients who have BCR–ABL-positive leukemia cells but do not observe obvious relapse. We focused on the immune response and conducted an immune analysis using clinical samples from the imatinib discontinuation study, JALSG-STIM213. The results showed that, in the group that maintained TFR for 3 years, changes in regulatory T (Treg) cells were observed early after stopping imatinib treatment. The effector Treg (eTreg) cells increased transiently at 1 month after stopping imatinib and then returned to baseline at 3 months after stopping imatinib treatment. There was no difference in the Treg phenotype, and CD8+ T cells in the TFR group were relatively activated. High concentrations of imatinib before stopping were negatively correlated with eTreg cells after stopping imatinib. These data suggest immunological involvement in the maintenance of the TFR, and that Treg cells after stopping imatinib might be a biomarker for TFR. Furthermore, high imatinib exposure may have a negative immunological impact on the continuous TFR.

Nilotinib and Dasatinib Evoked Distinct Immune Effects during Tfr Phase of Each Discontinuation Trial

Nilotinib and Dasatinib Evoked Distinct Immune Effects during Tfr Phase of Each Discontinuation Trial

Acsbg1-dependent mitochondrial fitness is a metabolic checkpoint for tissue Treg cell homeostasis.

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.

Cytokines, Hormones and Cellular Regulatory Mechanisms Favoring Successful Reproduction

Its semi-allogeneic nature renders the conceptus vulnerable to attack by the maternal immune system. Several protective mechanisms operate during gestation to correct the harmful effects of anti-fetal immunity and to support a healthy pregnancy outcome. Pregnancy is characterized by gross alterations in endocrine functions. Progesterone is indispensable for pregnancy and humans, and it affects immune functions both directly and via mediators. The progesterone-induced mediator - PIBF - acts in favor of Th2-type immunity, by increasing Th2 type cytokines production. Except for implantation and parturition, pregnancy is characterized by a Th2-dominant cytokine pattern. Progesterone and the orally-administered progestogen dydrogesterone upregulate the production of Th2-type cytokines and suppress the production of Th1 and Th17 cytokine production in vitro. This is particularly relevant to the fact that the Th1-type cytokines TNF-α and IFN-γ and the Th17 cytokine IL-17 have embryotoxic and anti-trophoblast activities. These cytokine-modulating effects and the PIBF-inducing capabilities of dydrogesterone may contribute to the demonstrated beneficial effects of dydrogesterone in recurrent spontaneous miscarriage and threatened miscarriage. IL-17 and IL-22 produced by T helper cells are involved in allograft rejection, and therefore could account for the rejection of paternal HLA-C-expressing trophoblast. Th17 cells (producing IL-17 and IL-22) and Th22 cells (producing IL-22) exhibit plasticity and could produce IL-22 and IL-17 in association with Th2-type cytokines or with Th1-type cytokines. IL-17 and IL-22 producing Th cells are not harmful for the conceptus, if they also produce IL-4. Another important protective mechanism is connected with the expansion and action of regulatory T cells, which play a major role in the induction of tolerance both in pregnant women and in tumour-bearing patients. Clonally-expanded Treg cells increase at the feto-maternal interface and in tumour-infiltrating regions. While in cancer patients, clonally-expanded Treg cells are present in peripheral blood, they are scarce in pregnancy blood, suggesting that fetal antigen-specific tolerance is restricted to the foeto-maternal interface. The significance of Treg cells in maintaining a normal materno-foetal interaction is underlined by the fact that miscarriage is characterized by a decreased number of total effector Treg cells, and the number of clonally-expanded effector Treg cells is markedly reduced in preeclampsia. In this review we present an overview of the above mechanisms, attempt to show how they are connected, how they operate during normal gestation and how their failure might lead to pregnancy pathologies.

Human Bone Marrow Mesenchymal Stromal/Stem Cell-Derived Extracellular Vesicles Ameliorate Graft-Versus-Host Disease-Related Manifestations

A substantial proportion of patients who receive allogeneic hematopoietic stem cell transplantation develop an immunologic adverse event of acute graft-versus-host disease (GVHD). Cell therapy with bone marrow mesenchymal stromal/stem cells (BM-MSC) is one of the effective treatments for such patients with GVHD. Lines of evidence have suggested that BM-MSC inhibit the function of immune cells mainly through secretion of soluble immune modulators and partially through cell-to-cell contact-dependent mechanism. However, further understanding of how they work has been an important issue. Recently, extracellular vesicles (EV) gain interests as mediators based on their capacity of transmitting signals to sites of action regardless of physiological barriers to reach. In this study, we examined the effects of human BM-MSC-derived EV on clinical, histological and immunologic manifestations of the acute GVHD model mice. We also analyzed whether biological processes mediated by microRNA (miRNA) in human BM-MSC-derived EV are involved in such immunologic effects.Human MSC were isolated from BM samples purchased from AllCells (Alameda, CA) based on our previously published method (Biochem Biophys Res Commun 2016;469:823). EV were isolated from the culture supernatant of BM-MSC by using the Total Exosome Isolation kit (Invitrogen, Carlsbad, CA). We confirmed that the isolated EV expressed CD63 and CD81 by immunoblot analysis and showed morphology of saucer-like shape by transmission electron microscopy. For in vitro experiments, peripheral blood mononuclear cells (PBMC) were activated by anti-CD3/CD28 antibodies with a Dynabeads Human T-Activator (Life Technologies AS, Oslo, Norway). For in vivo experiments, we used a mouse model where GVHD was induced by intravenously injecting spleen cells (1 x 108 per mouse) from C57BL/6 mice (H-2b) into irradiated (8 Gy) BDF1 mice (H-2b x d). The severity of GVHD was assessed histologically and clinically as previously described method (Blood 1996;88:3230, J Clin Invest 1998;102:115).We first tested the effects of BM-MSC-derived EV on T cell subsets in the expansion culture of anti-CD3/CD28-stimulated PBMC. In culture with human BM-MSC-derived EV, the expansion of PBMC was suppressed. Flow cytometric analysis showed that the expansion of CD3+ T cells including CD4+ and CD8+ T cells was suppressed. The frequency of CD45RA+Foxp3low cells (naive Treg cells) was higher and that of CD45RA-Foxp3high cells (effector Treg cells) was lower in culture with EV than those in a single culture of PBMC. In addition, the ratio of CD8/naive Treg cells was lower in culture with EV than that in a single culture of PBMC. Thus, BM-MSC-derived EV suppressed the T cell expansion and preserved naive Treg cells.We then investigated the effects of BM-MSC-derived EV on acute GVHD in mouse model. Systemic infusion of human BM-MSC-derived EV significantly prolonged the survival of GVHD mice with the median survival period of 16 days while that was 10 days in control untreated GVHD mice. The clinical scores of BM-MSC-derived EV-treated mice were lower than those of the control mice, indicating that EV ameliorated systemic symptoms of GVHD. In the histological assessment of GVHD-targeted organs, EV treatment significantly mitigated GVHD-associated abnormalities in specimens particularly from large bowel. Flow cytometric analysis of PB from the BM-MSC-derived EV-treated GVHD mice indicated that both CD4+ and CD8+ T cells were suppressed, and CD62L-CD44+ T cells was decreased and CD62L+CD44- T cells was increased compared with the control untreated GVHD mice. In addition, EV-treated mice still contained substantial Treg population. Thus, EV suppressed functional differentiation of peripheral T cells from naïve phenotype to effector phenotype and did not enhance depletion of Treg cells. Collectively, BM-MSC-derived EV showed immunomodulatory effects in murine GVHD model.Finally, we performed microarray analysis of microRNAs in BM-MSC-derived EV and found down-regulated cell proliferative processes as identified by Gene Ontology enrichment analysis.This study revealed that BM-MSC-derived EV captured the therapeutic effects of cell-of-origin against GVHD in association with immunologic mechanism of T cell suppression and peripheral naïve T cell preservation. Our findings provide the basis of BM-MSC-mediated anti-GVHD effect with the EV-mediated mechanism. DisclosuresTakaori-Kondo:celgene: Honoraria, Research Funding; Bristol-Myers Squibb, Novartis, Janssen pharma, Pfizer: Honoraria.

Conserved human effector Treg cell transcriptomic and epigenetic signature in arthritic joint inflammation

Treg cells are critical regulators of immune homeostasis, and environment-driven Treg cell differentiation into effector (e)Treg cells is crucial for optimal functioning. However, human Treg cell programming in inflammation is unclear. Here, we combine transcriptional and epigenetic profiling to identify a human eTreg cell signature. Inflammation-derived functional Treg cells have a transcriptional profile characterized by upregulation of both a core Treg cell (FOXP3, CTLA4, TIGIT) and effector program (GITR, BLIMP-1, BATF). We identify a specific human eTreg cell signature that includes the vitamin D receptor (VDR) as a predicted regulator in eTreg cell differentiation. H3K27ac/H3K4me1 occupancy indicates an altered (super-)enhancer landscape, including enrichment of the VDR and BATF binding motifs. The Treg cell profile has striking overlap with tumor-infiltrating Treg cells. Our data demonstrate that human inflammation-derived Treg cells acquire a conserved and specific eTreg cell profile guided by epigenetic changes, and fine-tuned by environment-specific adaptations.

Post-Translational Modifications in Transcription Factors that Determine T Helper Cell Differentiation.

CD4+ T helper (Th) cells play a crucial role in the modulation of innate and adaptive immune responses through the differentiation of Th precursor cells into several subsets, including Th1, Th2, Th17, and regulatory T (Treg) cells. Effector Th and Treg cells are distinguished by the production of signature cytokines and are important for eliminating intracellular and extracellular pathogens and maintaining immune homeostasis. Stimulation of naïve Th cells by T cell receptor and specific cytokines activates master transcription factors and induces lineage specification during the differentiation of Th cells. The master transcription factors directly activate the transcription of signature cytokine genes and also undergo post-translational modifications to fine-tune cytokine production and maintain immune balance through cross-regulation with each other. This review highlights the post-translational modifications of master transcription factors that control the differentiation of effector Th and Treg cells and provides additional insights on the immune regulation mediated by protein arginine-modifying enzymes in effector Th cells.

Peripheral Blood from Rheumatoid Arthritis Patients Shows Decreased Treg CD25 Expression and Reduced Frequency of Effector Treg Subpopulation

Rheumatoid arthritis (RA) is a common autoimmune disease characterized by immune cell infiltration of the synovium, leading to the loss of cartilage, bone, and joint function. Although regulatory T (Treg) cells are thought to modulate the initiation and progression of RA, a consensus has yet to be reached regarding the function and composition of Treg cells in RA patients. To address these discrepancies, we analyzed not only the total Treg frequency but also that of Treg subpopulations in the peripheral blood of RA patients and healthy controls by flow cytometry. We found that the total Treg population was not significantly different between RA and control subjects. However, the effector Treg cell subgroup, defined as CD45RA−CD25hi, showed markedly decreased frequency in RA patients. In addition, the total Treg population from RA patients showed a significant decline in the expression of CD25. Both the naïve and effector Treg subgroups also showed marked reduction of CD25 expression in RA patients compared to controls. These data suggest that the decreased frequency of effector Treg cells and overall reduction of CD25 expression in Treg cells in the peripheral blood may be evidence of altered Treg homeostasis associated with RA pathogenesis.

N-cadherin inhibitor creates a microenvironment that protect TILs from immune checkpoints and Treg cells

BackgroundFew patients with prostate cancer benefit from current immunotherapies. Therefore, we aimed to explore new strategies to change this paradigm.MethodsHuman tissues, cell lines and in vivo experiments were used to...

Efficient IL-2R signaling differentially affects the stability, function, and composition of the regulatory T-cell pool

Signaling via interleukin-2 receptor (IL-2R) is a requisite for regulatory T (Treg) cell identity and function. However, it is not completely understood to what degree IL-2R signaling is required for Treg cell homeostasis, lineage stability and function in both resting and inflammatory conditions. Here, we characterized a spontaneous mutant mouse strain endowed with a hypomorphic Tyr129His variant of CD25, the α-chain of IL-2R, which resulted in diminished receptor expression and reduced IL-2R signaling. Under noninflammatory conditions, Cd25Y129H mice harbored substantially lower numbers of peripheral Treg cells with stable Foxp3 expression that prevented the development of spontaneous autoimmune disease. In contrast, Cd25Y129H Treg cells failed to efficiently induce immune suppression and lost lineage commitment in a T-cell transfer colitis model, indicating that unimpaired IL-2R signaling is critical for Treg cell function in inflammatory environments. Moreover, single-cell RNA sequencing of Treg cells revealed that impaired IL-2R signaling profoundly affected the balance of central and effector Treg cell subsets. Thus, partial loss of IL-2R signaling differentially interferes with the maintenance, heterogeneity, and suppressive function of the Treg cell pool.

Acsbg1 Dependent Mitochondrial Fitness is a Metabolic Checkpoint for Tissue T <sub>reg</sub> Cell Homeostasis

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 and the function of Treg cells. Some ACSL members, a family of acyl-CoA synthase, are expressed in T cells, but their function remains unclear. Using a combination of RNA-seq and proteome analyses, we found that Acsbg1, a member of ACSL, is selectively expressed in Treg cells. We herein show that the genetic deletion and pharmacological inhibition of Acsbg1 causes not only mitochondrial dysfunction, but also dampens other metabolic pathways including glycolysis and the TCA-cycle. The extrinsic supplementation of sgAcsbg1 Treg cells with oleoyl-CoA restored the phenotype of the Treg metabolic signature. Furthermore, we also found evidence of this pathway in ST2 + effector Treg cells in the lung, which underlies the enhanced immunosuppressive capacity in the airway inflammation. Thus, Acsbg1 serves as a metabolic checkpoint governing Treg cell homeostasis and the resolution of lung inflammation.

Protein Prenylation Drives Discrete Signaling Programs for the Differentiation and Maintenance of Effector Treg Cells

Effector regulatory T (eTreg) cells are essential for immune tolerance and depend upon Tcell receptor (TCR) signals for generation. The immunometabolic signaling mechanisms that promote the differentiation and maintenance of eTreg cells remain unclear. Here, we show that isoprenoid-dependent posttranslational lipid modifications dictate eTreg cell accumulation and function by intersecting with TCR-induced intracellular signaling. We find that isoprenoids are essential for activated Treg cell suppressive activity, and Treg cell-specific deletion of the respective farnesylation- and geranylgeranylation-promoting enzymes Fntb or Pggt1b leads to the development of fatal autoimmunity, associated with reduced eTreg cell accumulation. Mechanistically, Fntb promotes eTreg cell maintenance by regulating mTORC1 activity and ICOS expression. In contrast, Pggt1b acts as a rheostat of TCR-dependent transcriptional programming and Rac-mediated signaling for establishment of eTreg cell differentiation and immune tolerance. Therefore, our results identify bidirectional metabolic signaling, specifically between immunoreceptor signaling and metabolism-mediated posttranslational lipid modifications, for the differentiation and maintenance of eTreg cells.

Regulatory T cell subsets in bullous pemphigoid and dipeptidyl peptidase-4 inhibitor-associated bullous pemphigoid

BackgroundRegulatory T (Treg) cells play an essential role in peripheral immune tolerance. Bullous pemphigoid (BP) is the most common blistering disease and is caused by autoantibodies to two BP antigens: type XVII collagen and BP230. Recently, we reported that Treg cell dysfunction may cause the production of autoantibodies to BP antigens. Several studies have suggested an association between Treg cells and BP pathogenesis. However, Treg cells are heterogeneous in humans, leading to inconsistent results in previous studies. ObjectiveTo assess functional Treg subsets in BP. MethodsWe examined three distinct Treg subsets in conventional BP (cBP) patients before versus after systemic corticosteroid treatment, dipeptidyl peptidase-4 inhibitor-associated BP (DPP-4i-BP) patients, younger controls and older controls. ResultsWe found that total Treg cells and all Treg cell subsets were increased in cBP patients before treatment and decreased by systemic corticosteroid treatment. In contrast, neither total Treg cells nor all Treg subsets were increased in DPP-4i-BP. Notably, CD45RA− Foxp3hi effector Treg cells positively correlated with disease severity in cBP, whereas CD45RA+Foxp3lo naïve Treg cells positively correlated with the disease severity in DPP-4i-BP. ConclusionThese findings suggest that Treg cells are differently involved in the pathogeneses of cBP and DPP-4i-BP.

Regulatory T Cell-Specific Epigenomic Region Variants Are a Key Determinant of Susceptibility to Common Autoimmune Diseases

The contribution of FOXP3-expressing naturally occurring regulatory T (Treg) cells to common polygenic autoimmune diseases remains ambiguous. Here, we characterized genome-wide epigenetic profiles (CpG methylation and histone modifications) of human Treg and conventional T (Tconv) cells in naive and activated states. We found that single-nucleotide polymorphisms (SNPs) associated with common autoimmune diseases were predominantly enriched in CpG demethylated regions (DRs) specifically present in naive Treg cells but much less enriched in activation-induced DRs common in Tconv and Treg cells. Naive Treg cell-specific DRs were largely included in Treg cell-specific super-enhancers and closely associated with transcription and other epigenetic changes in naive and effector Treg cells. Thus, naive Treg cell-specific CpG hypomethylation had a key role in controlling Treg cell-specific gene transcription and epigenetic modification. The results suggest possible contribution of altered function or development of natural Treg cells to the susceptibility to common autoimmune diseases.