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Mutations in NF-κB-related molecules result in combined immunodeficiency characterized by recurrent infection. In this study, we aimed to investigate the association between mutations in NF-κB family members, RELA, RELB, and RELC, and regulatory T cell (Treg) function in humans. RELA, RELB, and RELC were knocked out using CRISPR/Cas9-mediated homologous recombination in CD4+/CD8+ T cells and Tregs isolated from healthy donors. The RELA, RELB, and RELC knockouts did not alter the phenotype or cytokine production profile of CD4+/CD8+ T cells or Jurkat cells. Similar to that observed in knockout mice, RELA or RELC knockout in MT-2 cells and freshly isolated Tregs reduced FOXP3 expression and the immune suppressive function of Tregs. Additionally, PD-L1 expression in effector T cells and Tregs decreased considerably following RELC knockdown. These findings demonstrated that the deletion of RELA or RELC resulted in the loss of Treg-like phenotype and function owing to the downregulation of FOXP3 expression.

Drug reactions with eosinophilia and systemic symptoms (DRESS) and Stevens‐Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) are severe cutaneous adverse hypersensitivity reactions with distinct clinical manifestations. Regulatory T (Treg) cells may behave differently in these syndromes, contributing to their diverse clinical features and outcomes. This study compared Treg dynamics between DRESS and SJS/TEN patients during the acute and recovery phases. Flow cytometry quantitatively analysed and defined the immunophenotype of CD4+CD25+CD127−FoxP3+ Tregs in blood from DRESS and SJS/TEN patients indicated that Treg percentages were lowest in DRESS patients during the acute phase compared to those in the recovery phase in DRESS patients and the acute phase in SJS/TEN patients. During the acute phase, CTLA‐4 expression in Tregs in both DRESS patients with and without autoimmune sequelae was significantly increased, while only DRESS patients without autoimmune sequelae had elevated OX40 expression compared to the healthy controls. High IL‐10 expression in Tregs during the acute phase in SJS/TEN patients was also observed. The suppressive function of Tregs was lower in DRESS compared to SJS/TEN, which was determined using a suppression assay by co‐culturing autologous Treg and effector T cells. Furthermore, NanoString technology explored mRNA profiles in Tregs. Genes associated with the JAK/STAT pathway were found to be downregulated during the acute phase in DRESS patients who later developed autoimmune sequelae. Our findings evidenced impaired Treg function in DRESS compared to SJS/TEN. The early disturbance of the JAK/STAT pathway may serve as a prognostic marker for autoimmune development in DRESS patients. [ABSTRACT FROM AUTHOR]

Regulatory T cells (Tregs) play a central role in modulating adaptive immune responses in humans and mice. The precise biological role of non-canonical nuclear factor ‘κ-light-chain-enhancer’ of activated B cells (NFKB) signaling in human Tregs has yet to be fully elucidated. To gain insight into this process, a Treg-like cell line (MT-2) was genetically modified using CRISPR/Cas9. Interestingly, NFKB2 knockout MT-2 cells exhibited downregulation of FOXP3, while NFKB1 knockout did not. Additionally, mRNA expression of FOXP3-dependent molecules was significantly reduced in NFKB2 knockout MT-2 cells. To better understand the functional role of the NFKB signaling, the NFKB1/NFKB2 loci of human primary Tregs were genetically edited using CRISPR/Cas9. Similar to MT-2 cells, NFKB2 knockout human Tregs displayed significantly reduced FOXP3 expression. Furthermore, NFKB2 knockout human Tregs showed downregulation of FOXP3-dependent molecules and a diminished suppressive function compared to wild-type and NFKB1 knockout Tregs. These findings indicate that non-canonical NFKB signaling maintains a Treg-like phenotype and suppressive function in human Tregs through the FOXP3-dependent regulatory T cell program.

Forkhead Box P3 (FOXP3) is crucial for the development and suppressive function of human regulatory T cells (Tregs). There are two predominant FOXP3 splicing isoforms in healthy humans, the full-length isoform and the isoform lacking exon 2, with different functions and regulation mechanisms. FOXP3 splicing isoforms show distinct abilities in the cofactor interaction and the nuclear translocation, resulting in different effects on the differentiation, cytokine secretion, suppressive function, linage stability, and environmental adaptation of Tregs. The balance of FOXP3 splicing isoforms is related to autoimmune diseases, inflammatory diseases, and cancers. In response to environmental challenges, FOXP3 transcription and splicing can be finely regulated by T cell antigen receptor stimulation, glycolysis, fatty acid oxidation, and reactive oxygen species, with various signaling pathways involved. Strategies targeting energy metabolism and FOXP3 splicing isoforms in Tregs may provide potential new approaches for the treatment of autoimmune diseases, inflammatory diseases, and cancers. In this review, we summarize recent discoveries about the FOXP3 splicing isoforms and address the metabolic regulation and specific functions of FOXP3 splicing isoforms in Tregs. [ABSTRACT FROM AUTHOR]

• The m6A methyltransferase Mettl14 is involved in the generation of in vitro-induced Tregs (iTregs). • The methyltransferase Mettl14 is necessary for the maintenance of functional iTregs. • Mettl14-mediated m6A modification disrupted iTregs polarization by activating the mTOR-dependent pathway. • Our findings revealed that Mettl14 as a positive regulator has great relevance for improving the iTregs stability and function. Induced regulatory T cell (iTregs) can be generated in vitro. Thus, iTregs-based therapeutics are receiving increased attention for their potential to treat autoimmune diseases and prevent transplant rejection. However, iTregs fail to maintain FoxP3 expression and suppressive activity, which limits their clinical application. Increasing lines of evidence suggest that methyltransferase-like 14 (METTL14), a critical component of the m6A writer complex, regulates the stability and function of the Treg cells. However, beyond meeting the epigenetic modification of Treg cells, whether Mettl14 plays a role in the fate determination of iTregs is unclear. Here, we systemically investigated the potential function of METTL14 in iTregs differentiation and regulatory activity. In our study, iTregs were generated from CD4+ naïve T cells under iTreg-polarizing conditions, we found that the expression of METTL14 was increased in iTregs compared with CD4+naïve T cells. Subsequently, the expression of METTL14 was knocked down by siRNA-METTL14 interference in CD4+ naïve T cells and cultured under iTreg-polarizing conditions. According to the results, Mettl14 deficiency resulted in the disruption of iTregs differentiation evidenced by the limited FoxP3 expression. Meanwhile, inflammatory cytokines such as IFN-γ and IL-17a were upregulated in cultured iTregs. We next determined the functional change in METTL14-deficient iTregs. The results of the colitis development in Rag1 −/− mice and CFSE assays revealed that loss of METTL14 significantly compromised the suppressive function of iTregs in vivo and in vitro. We further checked the altered signaling pathway in METTL14-deficient iTregs. We found that reduced METTL14 leads to activation of the mTOR pathway with increased p-mTOR and p-p70S6K, which are known to modulate the suppressive function of iTregs. In conclusion, our study revealed that Mettl14 plays a critical role in the development and suppressive function of iTregs in vitro and could thus serve as a regulatory element for stabilizing iTregs in cell-based therapy. [ABSTRACT FROM AUTHOR]

Regulatory T cells are suppressive immune cells used in various clinical and therapeutic applications. Canonical regulatory T cells express CD4, FOXP3, and CD25, which are considered definitive markers of their regulatory T-cell status when expressed together. However, a subset of noncanonical regulatory T cells expressing only CD4 and FOXP3 have recently been described in some infection contexts. Using a unique mouse model for the first time demonstrated that the TCF-1 regulation of regulatory T-cell suppressive function is not limited to the thymus during development. Our data showed that TCF-1 also regulated regulatory T cells' suppressive ability in secondary organs and graft-vs-host disease target organs as well as upregulating noncanonical regulatory T cells. Our data demonstrated that TCF-1 regulates the suppressive function of regulatory T cells through critical molecules like GITR and PD-1, specifically by means of noncanonical regulatory T cells. Our in vitro approaches show that TCF-1 regulates the regulatory T-cell effector-phenotype and the molecules critical for regulatory T-cell migration to the site of inflammation. Using in vivo models, we show that both canonical and noncanonical regulatory T cells from TCF-1 cKO mice have a superior suppressive function, as shown by their ability to control conventional T-cell proliferation, avert acute graft-vs-host disease, and limit tissue damage. Thus, for the first time, we provide evidence that TCF-1 negatively regulates the suppressive ability of canonical and noncanonical regulatory T cells. These findings provide evidence that TCF-1 is a novel target for developing strategies to treat alloimmune disorders. [ABSTRACT FROM AUTHOR]

Abstract Background The plasticity of T helper-17 (Th17) and regulatory T (Treg) cells may be a clue to pathogenesis of Juvenile Idiopathic Arthritis (JIA). It is still unclear, whether targeted suppression of Interleukin (IL)-17 is able to influence regulatory function of Treg to control pro-inflammatory effectors in JIA. This study aimed to assess the effect of a Th17-stimulating cytokine environment and of IL-17A-inhibition on phenotype plasticity and suppressive function of Treg derived from JIA patients. Methods Th17 and Treg characteristics of CD4+ helper T cells were investigated in blood samples of JIA patients with oligo- and polyarticular pattern and healthy controls (HC). Isolated CD4+CD25+CD127− cells defined as Treg were cultivated with Th17-inducing cytokine environment as well as with IL-17A-inhibitors and analyzed for plasticity of phenotype by flow cytometry. Furthermore, inhibitory function of Treg on autologous effectors after cultivation with these stimuli was determined by suppression assays. Results Our findings demonstrated significantly elevated proportions of Th17 and Th17-like Treg in JIA compared to HC. After incubation with Th17-inducing stimuli, increased FoxP3 expression in separated Treg in JIA and an impaired suppressive capacity in JIA and HC were found. Blockade of IL-17A resulted in adjustment of FoxP3-expression in JIA to proportions found in controls and in regular suppressive function. Conclusions Our results demonstrate an induction of FoxP3 expressing Treg by Th17-inducing cytokines with concomitant mitigated suppressive function. In contrast, specific IL-17A blockade maintains suppressive Treg function and adjusted FoxP3-expression in JIA to levels found in controls. These findings may help to provide experimental evidence for the successful clinical use of IL-17A inhibition in JIA patients.

Background: The plasticity of T helper-17 (Th17) and regulatory T (Treg) cells may be a clue to pathogenesis of Juvenile Idiopathic Arthritis (JIA). It is still unclear, whether targeted suppression of Interleukin (IL)-17 is able to influence regulatory function of Treg to control pro-inflammatory effectors in JIA. This study aimed to assess the effect of a Th17-stimulating cytokine environment and of IL-17A-inhibition on phenotype plasticity and suppressive function of Treg derived from JIA patients. Methods: Th17 and Treg characteristics of CD4+ helper T cells were investigated in blood samples of JIA patients with oligo- and polyarticular pattern and healthy controls (HC). Isolated CD4+CD25+CD127− cells defined as Treg were cultivated with Th17-inducing cytokine environment as well as with IL-17A-inhibitors and analyzed for plasticity of phenotype by flow cytometry. Furthermore, inhibitory function of Treg on autologous effectors after cultivation with these stimuli was determined by suppression assays. Results: Our findings demonstrated significantly elevated proportions of Th17 and Th17-like Treg in JIA compared to HC. After incubation with Th17-inducing stimuli, increased FoxP3 expression in separated Treg in JIA and an impaired suppressive capacity in JIA and HC were found. Blockade of IL-17A resulted in adjustment of FoxP3-expression in JIA to proportions found in controls and in regular suppressive function. Conclusions: Our results demonstrate an induction of FoxP3 expressing Treg by Th17-inducing cytokines with concomitant mitigated suppressive function. In contrast, specific IL-17A blockade maintains suppressive Treg function and adjusted FoxP3-expression in JIA to levels found in controls. These findings may help to provide experimental evidence for the successful clinical use of IL-17A inhibition in JIA patients. [ABSTRACT FROM AUTHOR]

Regulatory T cell (Treg) adoptive cell therapy (ACT) represents an emerging strategy for restoring immune tolerance in autoimmune diseases. Tregs are commonly purified using a CD4+CD25+CD127lo/- gating strategy, which yields a mixed population: 1) cells expressing the transcription factors, FOXP3 and Helios, that canonically define lineage stable thymic Tregs and 2) unstable FOXP3+Helios- Tregs. Our prior work identified the autoimmune disease risk-associated locus and costimulatory molecule, CD226, as being highly expressed not only on effector T cells but also, interferon-γ (IFN-γ) producing peripheral Tregs (pTreg). Thus, we sought to determine whether isolating Tregs with a CD4+CD25+CD226- strategy yields a population with increased purity and suppressive capacity relative to CD4+CD25+CD127lo/- cells. After 14d of culture, expanded CD4+CD25+CD226- cells displayed a decreased proportion of pTregs relative to CD4+CD25+CD127lo/- cells, as measured by FOXP3+Helios- expression and the epigenetic signature at the FOXP3 Treg-specific demethylated region (TSDR). Furthermore, CD226- Tregs exhibited decreased production of the effector cytokines, IFN-γ, TNF, and IL-17A, along with increased expression of the immunoregulatory cytokine, TGF-β1. Lastly, CD226- Tregs demonstrated increased in vitro suppressive capacity as compared to their CD127lo/- counterparts. These data suggest that the exclusion of CD226-expressing cells during Treg sorting yields a population with increased purity, lineage stability, and suppressive capabilities, which may benefit Treg ACT for the treatment of autoimmune diseases. [ABSTRACT FROM AUTHOR]

Regulatory T cell (Treg) adoptive cell therapy (ACT) represents an emerging strategy for restoring immune tolerance in autoimmune diseases. Tregs are commonly purified using a CD4+CD25+CD127lo/- gating strategy, which yields a mixed population: 1) cells expressing the transcription factors, FOXP3 and Helios, that canonically define lineage stable thymic Tregs and 2) unstable FOXP3+Helios- Tregs. Our prior work identified the autoimmune disease risk-associated locus and costimulatory molecule, CD226, as being highly expressed not only on effector T cells but also, interferon-γ (IFN-γ) producing peripheral Tregs (pTreg). Thus, we sought to determine whether isolating Tregs with a CD4+CD25+CD226- strategy yields a population with increased purity and suppressive capacity relative to CD4+CD25+CD127lo/- cells. After 14d of culture, expanded CD4+CD25+CD226- cells displayed a decreased proportion of pTregs relative to CD4+CD25+CD127lo/- cells, as measured by FOXP3+Helios- expression and the epigenetic signature at the FOXP3 Treg-specific demethylated region (TSDR). Furthermore, CD226- Tregs exhibited decreased production of the effector cytokines, IFN-γ, TNF, and IL-17A, along with increased expression of the immunoregulatory cytokine, TGF-β1. Lastly, CD226- Tregs demonstrated increased in vitro suppressive capacity as compared to their CD127lo/- counterparts. These data suggest that the exclusion of CD226-expressing cells during Treg sorting yields a population with increased purity, lineage stability, and suppressive capabilities, which may benefit Treg ACT for the treatment of autoimmune diseases.

FOXP3 is the master transcription factor in both murine and human FOXP3+ regulatory T cells (Tregs), a T-cell subset with a central role in controlling immune responses. Loss of the functional Foxp3 protein in scurfy mice leads to acute early-onset lethal lymphoproliferation. Similarly, pathogenic FOXP3 mutations in humans lead to immunodysregulation, polyendocrinopathy, enteropathy, and X-linked (IPEX) syndrome, which are characterized by systemic autoimmunity that typically begins in the first year of life. However, although pathogenic FOXP3 mutations lead to overlapping phenotypic consequences in both systems, FOXP3 in human Tregs, but not mouse, is expressed as two predominant isoforms, the full length (FOXP3FL) and the alternatively spliced isoform, delta 2 (FOXP3Δ2). Here, using CRISPR/Cas9 to generate FOXP3 knockout CD4+ T cells (FOXP3KOGFP CD4+ T cells), we restore the expression of each isoform by lentiviral gene transfer to delineate their functional roles in human Tregs. When compared to FOXP3FL or FOXP3Δ2 alone, or double transduction of the same isoform, co-expression of FOXP3FL and FOXP3Δ2 induced the highest overall FOXP3 protein expression in FOXP3KOGFP CD4+ T cells. This condition, in turn, led to optimal acquisition of Treg-like cell phenotypes including downregulation of cytokines, such as IL-17, and increased suppressive function. Our data confirm that co-expression of FOXP3FL and FOXP3Δ2 leads to optimal Treg-like cell function and supports the need to maintain the expression of both when engineering therapeutics designed to restore FOXP3 function in otherwise deficient cells.

FOXP3 is the master transcription factor in both murine and human FOXP3+ regulatory T cells (Tregs), a T-cell subset with a central role in controlling immune responses. Loss of the functional Foxp3 protein in scurfy mice leads to acute early-onset lethal lymphoproliferation. Similarly, pathogenic FOXP3 mutations in humans lead to immunodysregulation, polyendocrinopathy, enteropathy, and X-linked (IPEX) syndrome, which are characterized by systemic autoimmunity that typically begins in the first year of life. However, although pathogenic FOXP3 mutations lead to overlapping phenotypic consequences in both systems, FOXP3 in human Tregs, but not mouse, is expressed as two predominant isoforms, the full length (FOXP3FL) and the alternatively spliced isoform, delta 2 (FOXP3Δ2). Here, using CRISPR/Cas9 to generate FOXP3 knockout CD4+ T cells (FOXP3KOGFP CD4+ T cells), we restore the expression of each isoform by lentiviral gene transfer to delineate their functional roles in human Tregs. When compared to FOXP3FL or FOXP3Δ2 alone, or double transduction of the same isoform, co-expression of FOXP3FL and FOXP3Δ2 induced the highest overall FOXP3 protein expression in FOXP3KOGFP CD4+ T cells. This condition, in turn, led to optimal acquisition of Treg-like cell phenotypes including downregulation of cytokines, such as IL-17, and increased suppressive function. Our data confirm that co-expression of FOXP3FL and FOXP3Δ2 leads to optimal Treg-like cell function and supports the need to maintain the expression of both when engineering therapeutics designed to restore FOXP3 function in otherwise deficient cells. [ABSTRACT FROM AUTHOR]

Regulatory T cells (Treg) are well-known for their immune regulatory potential and are essential for maintaining immune homeostasis. The rationale of Treg-based immunotherapy for treating autoimmunity and transplant rejection is to tip the immune balance of effector T cell-mediated immune activation and Treg-mediated immune inhibition in favor of Treg cells, either through endogenous Treg expansion strategies or adoptive transfer of ex vivo expanded Treg. Compelling evidence indicates that Treg show properties of phenotypic heterogeneity and instability, which has caused considerable debate in the field regarding their correct use. Consequently, for further optimization of Treg-based immunotherapy, it is vital to further our understanding of Treg proliferative, migratory, and suppressive behavior. It is increasingly appreciated that the functional profile of immune cells is highly dependent on their metabolic state. Although the metabolic profiles of effector T cells are progressively understood, little is known on Treg in this respect. The objective of this review is to outline the current knowledge of human Treg metabolic profiles associated with the regulation of Treg functionality. As such information on human Treg is still limited, where information was lacking, we included insightful findings from mouse studies. To assess the available evidence on metabolic pathways involved in Treg functionality, PubMed, and Embase were searched for articles in English indexed before April 28th, 2019 using “regulatory T lymphocyte,” “cell metabolism,” “cell proliferation,” “migration,” “suppressor function,” and related search terms. Removal of duplicates and search of the references was performed manually. We discerned that while glycolysis fuels the biosynthetic and bioenergetic needs necessary for proliferation and migration of human Treg, suppressive capacity is mainly maintained by oxidative metabolism. Based on the knowledge of metabolic differences between Treg and non-Treg cells, we additionally discuss and propose ways of how human Treg metabolism could be exploited for the betterment of tolerance-inducing therapies.

Objectives: Regulatory T cells (Tregs) are frequently functionally impaired in patients with granulomatosis with polyangiitis (GPA). However, the mechanism underlying their impaired function is unknown. Here, we hypothesized that Treg dysfunction in GPA is due to altered microRNA (miRNA) expression.Methods: RNA isolated from FACS-sorted memory (M) Tregs (CD4+CD45RO+CD25+CD127−) of 8 healthy controls (HCs) and 8 GPA patients without treatment was subjected to miRNA microarray analysis. Five differentially expressed miRNAs were validated in a larger cohort by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). An miRNA target gene database search revealed targets that were tested with RT-qPCR in MTregs from patients and HCs. cAMP levels were measured using flow cytometry.Results: Microarray analysis revealed 19 differentially expressed miRNAs, of which miR-142-3p was confirmed to be significantly upregulated in MTregs from GPA patients compared to those from HCs (1.9-fold, p = 0.03). In vitro overexpression of miR-142-3p lowered the suppressive capacity of MTregs (2.1-fold, p = 0.03), and miR-142-3p expression correlated negatively with the suppressive capacity (rho = −0.446, p = 0.04). Overexpression of miR-142-3p significantly decreased cAMP levels (p = 0.02) and tended to decrease the mRNA levels of a predicted target gene, adenylate cyclase 9 (ADCY9; p = 0.06). In comparison to those from HCs, MTregs from GPA patients had lower ADCY9 mRNA levels (2-fold, p = 0.008) and produced significantly less cAMP after stimulation. Importantly, induction of cAMP production in miR-142-3p overexpressed MTregs by forskolin restored their suppressive function in vitro.Conclusion: Overexpression of miR-142-3p in MTregs from GPA patients might cause functional impairment by targeting ADCY9, which leads to the suppression of cAMP production.

Regulatory T cells (Treg) are well-known for their immune regulatory potential and are essential for maintaining immune homeostasis. The rationale of Treg-based immunotherapy for treating autoimmunity and transplant rejection is to tip the immune balance of effector T cell-mediated immune activation and Treg-mediated immune inhibition in favor of Treg cells, either through endogenous Treg expansion strategies or adoptive transfer of ex vivo expanded Treg. Compelling evidence indicates that Treg show properties of phenotypic heterogeneity and instability, which has caused considerable debate in the field regarding their correct use. Consequently, for further optimization of Treg-based immunotherapy, it is vital to further our understanding of Treg proliferative, migratory, and suppressive behavior. It is increasingly appreciated that the functional profile of immune cells is highly dependent on their metabolic state. Although the metabolic profiles of effector T cells are progressively understood, little is known on Treg in this respect. The objective of this review is to outline the current knowledge of human Treg metabolic profiles associated with the regulation of Treg functionality. As such information on human Treg is still limited, where information was lacking, we included insightful findings from mouse studies. To assess the available evidence on metabolic pathways involved in Treg functionality, PubMed, and Embase were searched for articles in English indexed before April 28th, 2019 using "regulatory T lymphocyte," "cell metabolism," "cell proliferation," "migration," "suppressor function," and related search terms. Removal of duplicates and search of the references was performed manually. We discerned that while glycolysis fuels the biosynthetic and bioenergetic needs necessary for proliferation and migration of human Treg, suppressive capacity is mainly maintained by oxidative metabolism. Based on the knowledge of metabolic differences between Treg and non-Treg cells, we additionally discuss and propose ways of how human Treg metabolism could be exploited for the betterment of tolerance-inducing therapies. [ABSTRACT FROM AUTHOR]

Objectives: Regulatory T cells (Tregs) are frequently functionally impaired in patients with granulomatosis with polyangiitis (GPA). However, the mechanism underlying their impaired function is unknown. Here, we hypothesized that Treg dysfunction in GPA is due to altered microRNA (miRNA) expression. Methods: RNA isolated from FACS-sorted memory (M) Tregs (CD4+CD45RO+CD25+CD127−) of 8 healthy controls (HCs) and 8 GPA patients without treatment was subjected to miRNA microarray analysis. Five differentially expressed miRNAs were validated in a larger cohort by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR). An miRNA target gene database search revealed targets that were tested with RT-qPCR in MTregs from patients and HCs. cAMP levels were measured using flow cytometry. Results: Microarray analysis revealed 19 differentially expressed miRNAs, of which miR-142-3p was confirmed to be significantly upregulated in MTregs from GPA patients compared to those from HCs (1.9-fold, p = 0.03). In vitro overexpression of miR-142-3p lowered the suppressive capacity of MTregs (2.1-fold, p = 0.03), and miR-142-3p expression correlated negatively with the suppressive capacity (rho = −0.446, p = 0.04). Overexpression of miR-142-3p significantly decreased cAMP levels (p = 0.02) and tended to decrease the mRNA levels of a predicted target gene, adenylate cyclase 9 (ADCY9; p = 0.06). In comparison to those from HCs, MTregs from GPA patients had lower ADCY9 mRNA levels (2-fold, p = 0.008) and produced significantly less cAMP after stimulation. Importantly, induction of cAMP production in miR-142-3p overexpressed MTregs by forskolin restored their suppressive function in vitro. Conclusion: Overexpression of miR-142-3p in MTregs from GPA patients might cause functional impairment by targeting ADCY9, which leads to the suppression of cAMP production. [ABSTRACT FROM AUTHOR]

Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder characterized by production of auto-antibodies against platelet antigens. It is obvious that regulatory T cells (Tregs) have a major role in controlling immune homeostasis and preventing autoimmunity. To investigate the frequency and functions of Tregs, twenty ITP patients and twenty age- and sex- matched healthy controls were recruited. The peripheral blood mononuclear cells were isolated and the proportion of Tregs was defined by flow cytometry method. The expression of immune-regulatory markers, cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and glucocorticoid induced tumor necrosis factor receptor (GITR) were also assessed by quantitative Real-time polymerase chain reaction TaqMan method. For evaluation of Treg function, Tregs were enriched and their ability to inhibit proliferation of T cells was measured and levels of immune-regulatory cytokines IL-10 and Transforming growth factor beta (TGF-β) were also measured.Results showed that the frequency of Tregs and the mean fluorescence intensity of forkhead box P3 (FOXP3) protein significantly decreased in ITP patients compared to those in healthy controls. In addition, there was a significant reduction in relative expression of both CTLA-4 and GITR mRNA in ITP patients (p=0.02 and p=0.006, respectively). The suppressive function of Tregs also diminished in ITP patients compared to controls. Both IL-10 and TGF-β cytokines were produced in lower amounts in ITP patients than controls. It could be concluded that alteration in Treg frequency and functional characteristics might be responsible for loss of self-tolerance and subsequently destructive immune responses observed in ITP patients.

Objective. IL-35 is the most recently identified member of the IL-12 family. It consists of EBV-induced gene 3 (EBI3) and IL-12α chain p35. We investigated whether IL-35 enhances the in vitro immunosup-pressive function of peripheral blood isolated from patients with RA. Methods. Peripheral blood was harvested from 17 active and 10 inactive RA patients and IL-35 concentrations were quantified using an ELISA. An expression vector containing IL-35 with a FLAG tag at the carboxyl-terminus was constructed by covalently linking EBI3 and IL-12α (p35). The function of IL-35 was then evaluated in a suppression assay using T cells isolated from human RA patients with CD2, CD3 and CD28 antibodies. Results. Serum IL-35 levels and the number of Treg were decreased significantly in patients with active RA. There was a significant correlation between serum IL-35 and the 28-joint DAS with ESR (DAS28-ESR) in patients with active RA. IL-35 treatment enhanced the regulatory function, suppressing the levels of inflammatory cytokines such as IL-17 and IFN-γ and the cellular growth of effector T cells stimulated by conjugation with CD2, CD3 and CD28. Conclusion. These data revealed that IL-35 might suppress T cell activation during the peripheral immune responses of RA. Therefore our data suggest that IL-35 might have multiple therapeutic targets. [ABSTRACT FROM AUTHOR]

Follicular helper T ( TFH) cells and B cells are linked to the pathogenesis of ankylosing spondylitis ( AS). Follicular regulatory T ( TFR) cells suppress TFH cell and germinal center B cell numbers in vivo. The role of TFR cells in AS is unknown. The frequency of peripheral blood inducible FOXP3+ CXCR5+ CD4+ TFR cells and CXCR5+ CD4+ TFH cells were taken from 20 onset AS patients and 10 healthy controls, and were examined by flow cytometry, their disease activity were measured by the Bath Ankylosing Spondylitis Disease Activity Index. The concentrations of serum interleukin ( IL)-21, immunoglobulin G, immunoglobulin A, immunoglobulin M and C-reactive protein were examined, and the values of erythrocyte sedimentation rate were measured. The frequency of peripheral blood FOXP3+ CXCR5+ CD4+ TFR cells, CXCR5+ CD4+ TFH cells, the ratio of FOXP3+ CXCR5+ CD4+ TFR/ CXCR5+ CD4+ TFH cells and the concentration of serum IL-21 in the AS patients were significantly higher than those in the healthy controls ( P < 0.0001, P = 0.0027, P < 0.0001, P = 0.0039, respectively). The frequency of FOXP3+ CXCR5+ CD4+ TFR cells and the ratio of FOXP3+ CXCR5+ CD4+ TFR/ CXCR5+ CD4+ TFH cells still significantly rose in those patients after standard treatment ( P = 0.0006, P < 0.0001), the concentration of serum IL-21 decreased after treatment ( P = 0.0049), accompanied by significantly minimized disease activities. Furthermore, the TFR cells were negatively correlated with serum immunoglobulin A in those patients before treatment ( r = −0.582, P = 0.0071), and the frequency of TFR cells was negatively correlated with that of TFH cells and the concentration of serum IL-21 after treatment ( r = −0.550, P = 0.046; r = −0.581, P = 0.0371). TFR cells might participate in the pathogenesis of AS, and might be responsible for controlling the autoantibodies, the frequency and function of TFH cells to inhibit the development of AS. [ABSTRACT FROM AUTHOR]

Immune thrombocytopenic purpura (ITP) is an autoimmune bleeding disorder characterized by production of auto-antibodies against platelet antigens. It is obvious that regulatory T cells (Tregs) have a major role in controlling immune homeostasis and preventing autoimmunity. To investigate the frequency and functions of Tregs, twenty ITP patients and twenty age- and sexmatched healthy controls were recruited. The peripheral blood mononuclear cells were isolated and the proportion of Tregs was defined by flow cytometry method. The expression of immune-regulatory markers, cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and glucocorticoid induced tumor necrosis factor receptor (GITR) were also assessed by quantitative Real-time polymerase chain reaction TaqMan method. For evaluation of Treg function, Tregs were enriched and their ability to inhibit proliferation of T cells was measured and levels of immune-regulatory cytokines IL-10 and Transforming growth factor beta (TGF-β) were also measured.Results showed that the frequency of Tregs and the mean fluorescence intensity of forkhead box P3 (FOXP3) protein significantly decreased in ITP patients compared to those in healthy controls. In addition, there was a significant reduction in relative expression of both CTLA-4 and GITR mRNA in ITP patients (p=0.02 and p=0.006, respectively). The suppressive function of Tregs also diminished in ITP patients compared to controls. Both IL-10 and TGF-β cytokines were produced in lower amounts in ITP patients than controls. It could be concluded that alteration in Treg frequency and functional characteristics might be responsible for loss of self-tolerance and subsequently destructive immune responses observed in ITP patients. [ABSTRACT FROM AUTHOR]

Highlights: [•] Regulatory T cells number is decreased in CVID patients. [•] Regulatory T cells inhibitory function is decreased in CVID patients. [•] Tregs from CVID patients produce less IL-10 than those from healthy controls. [ABSTRACT FROM AUTHOR]

Naturally occurring CD4+CD25 + regulatory T cells (nTregs) that express high level of Foxp3 actively suppress pathological and physiological immune responses, contributing to the maintenance of immunological self-tolerance and immune homeostasis. Although Foxp3 is required for nTreg development and appears to be necessary for mature murine Treg function, the precise role of Foxp3 in regulating natural human Treg function in alloimmune response is unclear. In this study, we used siRNA-mediated gene silencing to knockdown Foxp3 expression in natural human Tregs and investigated the importance of Foxp3 in maintaining human nTreg suppressive function. We showed that Foxp3 knockdown resulted in impaired phenotype and nonresponsiveness, downregulated expression of function molecules, and reduced production of suppressive cytokines in nTregs. These changes correlated with diminished nTreg activity in suppressing proliferation of effector CD4+CD25 - T cells, their cytotoxicity against allogeneic target cells and production of effector cytokines in response to allogeneic stimulation. Thus, this study shows that ongoing Foxp3 expression is required for natural human Tregs to maintain their phenotype and suppressive function in the alloimmune response. [ABSTRACT FROM AUTHOR]

Objective The pathogenesis of dilated cardiomyopathy (DCM) is closely connected with dysfunction of the autoimmune system, and CD4+CD25highCD127low/- regulatory T (Treg) cells have a vital role in maintaining self-tolerance. In this study, we compared the frequency and regulatory function of Treg cells between DCM patients and normal controls. Methods and Results The frequencies of CD4+CD25+ T cells in DCM patients were statistically decreased compared with normal controls (p<0.05) by flow cytometry, and the levels of FOXP3 mRNA and protein expression in PBMCs (peripheral blood mononuclear cells) of DCM patients were lower than those of normal controls (p<0.01), using real-time RT-PCR assay and western blot. Notably, the suppressive capacity of CD4+CD25highCD127low/- regulatory T cells of DCM patients acting on autologous CD4+CD25- responder T (Tresp) cells seemed to be partially impaired (43.83±3.19% suppression versus 63.17±3.66% in normal controls, p=0.01). Surprisingly, Treg cells from DCM patients efficiently suppressed the proliferation of Tresp cells from normal subjects to the similar level as Treg cells from normal subjects on autologous Tresp cells (p=0.286), whereas Treg cells of normal subjects poorly inhibited the proliferation of Tresp cells from DCM patients. Conclusion The defective capacity of Treg cells suppressing autologous Tresp cells is attributed to the increasing resistance of Tresp cells to inhibition of Treg cells in DCM patients. Therefore, strategies to improve the susceptibility of Tresp cells to Treg cell-mediated suppression might benefit DCM patients. [ABSTRACT FROM AUTHOR]

Summary: Background: Patients with chronic ordinary urticaria (CU) are divided into two groups: 30–50% have chronic autoimmune urticaria, and the remainder have chronic idiopathic urticaria. CD4+CD25+ regulatory T (Treg) cells play critical roles in maintaining peripheral tolerance and preventing autoimmunity, but the characteristics of Treg cells have not yet been defined in CU. Objective: To identify whether CD4+ T cells play an important immunoregulatory role in the etiology of CU, we determined the frequencies and functions of circulating CD4+CD25+ and CD4+CD25− T cells in CU patients and healthy control subjects, with special focus on the characteristics of CD4+CD25+ T cells. Methods: Peripheral blood mononuclear cells (PBMCs) were obtained from CU and healthy controls in this study. The frequency of CD4+CD25+ T cells in PBMCs was detected by flow cytometry. The expression levels of forkhead box P3 (FOXP3) and transforming growth factor-β (TGF-β) in CD4+CD25+ T cells were detected by real-time PCR. Furthermore, the suppressive function of CD4+CD25+ T cells was analyzed. Additionally, the Th1/Th2 cytokine secretory profile in mitogen-stimulated CD4+CD25− T cells was measured by ELISA. Results: An increased frequency of CD4+CD25+ T cells was observed in CU patients (n =19) compared to control subjects (n =7). No significant difference was detected in the expression levels of FOXP3 or TGF-β between CU patients (n =14) and control subjects (n =7). Strikingly, the suppressive capacity of CD4+CD25+ Treg cells from 2 of 5 CU patients was partially defective. We also found that cytokine production from CD4+CD25− T cells was significantly reduced in CU patients (n =9) compared to healthy donors (n =11). Conclusions: Our data demonstrate that CD4+CD25+ and CD4+CD25− T cells in PBMCs exhibit defective functions in CU patients. [Copyright &y& Elsevier]

Regulatory T cells (Treg cells) are important for preventing autoimmunity and maintaining tissue homeostasis, but whether Treg cells can adopt tissue- or immune-context-specific suppressive mechanisms is unclear. Here, we found that the enzyme hydroxyprostaglandin dehydrogenase (HPGD), which catabolizes prostaglandin E 2 (PGE 2) into the metabolite 15-keto PGE 2 , was highly expressed in Treg cells, particularly those in visceral adipose tissue (VAT). Nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ)-induced HPGD expression in VAT Treg cells, and consequential Treg-cell-mediated generation of 15-keto PGE 2 suppressed conventional T cell activation and proliferation. Conditional deletion of Hpgd in mouse Treg cells resulted in the accumulation of functionally impaired Treg cells specifically in VAT, causing local inflammation and systemic insulin resistance. Consistent with this mechanism, humans with type 2 diabetes showed decreased HPGD expression in Treg cells. These data indicate that HPGD-mediated suppression is a tissue- and context-dependent suppressive mechanism used by Treg cells to maintain adipose tissue homeostasis. • HPGD is specifically upregulated in Treg cells and confers suppressive capabilities • HPGD-induced Tconv cell suppression is in part mediated by PPARγ signaling • HPGD expression in Treg cells is vital for VAT homeostasis and metabolic regulation • T2D patients have a reduced Treg cell fraction expressing lower amounts of HPGD Regulatory T (Treg) cells are important for preventing autoimmunity and maintaining tissue homeostasis. Schmidleithner et al. report a hydroxyprostaglandin dehydrogenase (HPGD)-mediated tissue- and context-dependent suppressor mechanism used by Treg cells to maintain adipose tissue homeostasis through the metabolism of PGE 2 into the PPARγ ligand 15-keto-PGE2, which is conserved in human and mouse. [ABSTRACT FROM AUTHOR]

Regulatory B cells (Bregs) participate in auto-tolerance maintenance and immune homeostasis. Despite their impact on many diseases and due to the difficulty to define them, knowledge about their origin and their physiological inducers is still unclear. The incomplete understanding about the generation of Bregs and their limited numbers in periphery make it difficult to develop Breg-based therapy. Therefore, identifying factors that promote their development would allow their ex-vivo production in order to create new immunotherapy. This project aims to test the capacity of several cytokines (Interleukin 1-beta (IL-1β), Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF), and Cluster of differentiation 40 ligand (CD40L)) and bacteria-derived oligodeoxynucleotides (CpG-ODN), alone or in combination, to generate B cells with regulatory phenotype and function. We have demonstrated that the Breg-associated phenotypes were heterogeneous between one and other stimulation conditions. However, the expression of other markers related to Bregs such as IL-10, CD80, CD86, CD71, Programmed cell death-1 (PD-1), and Programmed death-ligand 1 (PD-L1) was increased when cells were stimulated with CpG alone or in combination. Moreover, stimulated B cells presented a suppressive function on autologous activated peripheral blood mononuclear cells (PBMC) proliferation. Therefore, this work is the first step to demonstrate the feasibility to induce functional Breg-like cells in vitro and will then facilitate the way to produce Breg-like cells as a potential future cellular therapy. [ABSTRACT FROM AUTHOR]