Treg Cell Development Research Articles

Transcriptional regulation of adaptive and innate lymphoid lineage specification.

Once alerted to the presence of a pathogen, activated CD4+ T cells initiate distinct gene expression programs that produce multiple functionally specialized T helper (Th) subsets. The cytokine milieu present at the time of antigen encounter instructs CD4+ T cells to differentiate into interferon-(IFN)-γ-producing Th1 cells, interleukin-(IL)-4-producing Th2 cells, IL-17-producing Th17 cells, follicular T helper (Tfh) cells, or regulatory T (Treg) cells. In each of these Th cell subsets, a single transcription factor has been identified as a critical regulator of its specialized differentiation program. In this context, the expression of the "master regulator" is necessary and sufficient to activate lineage-specific genes while restricting the gene expression program of alternative Th fates. Thus, the transcription factor T-bet controls Th1 differentiation program, while the development of Th2, Th17, Tfh, and Treg cells is dependent on transcription factors GATA3, RORγt, Bcl6, and Foxp3, respectively. Nevertheless, master regulators or, more precisely, lineage-defining transcription factors do not function in isolation. In fact, they interact with a complex network of transcription factors, orchestrating cell lineage specification programs. In this review, we discuss the concept of the combinatorial interactions of key transcription factors in determining helper T cell identity. Additionally, lineage-defining transcription factors have well-established functions beyond their role in CD4+ Th subsets. They play critically important functions at distinct stages during T cell development in the thymus and they control the development of innate lymphoid cells (ILCs) in the bone marrow. In tracking the journey of T cells traversing from the thymus to the periphery and during the immune response, we discuss in broad terms developmental stage and context-dependent functions of lineage-defining transcription factors in regulating specification programs of innate and adaptive lymphocytes.

Epimedin C modulates the balance between Th9 cells and Treg cells through negative regulation of noncanonical NF-κB pathway and MAPKs activation to inhibit airway inflammation in the ovalbumin–induced murine asthma model

Allergic asthma is a common airway inflammatory disease and mainly caused by abnormal immune responses to allergens and viruses. The precise mechanisms of airway inflammation and airway hyper-responsiveness (AHR) are still not completely understood. CD4+ helper T cells (Th cells) serve as critical regulators of allergic immunity. The imbalance between T helper 9 (Th9) cells and forkhead box protein 3 (Foxp3)+ regulatory T (Treg) cells may contribute to airway inflammation in asthma. Epimedin C, a dominant compound isolated from Herba Epimedii, has shown anti-inflammatory effects and the immunoregulatory activity, such as increase of lymphocyte proliferation. However, the protective role of epimedin C in an experimental model of ovalbumin (OVA)-induced allergic airway inflammation and the underlying mechanism remain unknown. Female BALB/c mice were sensitized by intraperitoneal injection (i.p.) of OVA plus aluminum hydroxide (Alum) and subsequently challenged with an aerosol of 3% OVA in saline. Mice were treated with different concentrations of epimedin C (20 mg/kg/d, 40 mg/kg/d, 80 mg/kg/d) for 4 weeks. Experimental endpoints were evaluated via the analysis of AHR to acetyl-β-methacholine (Mch), differential inflammatory cell counts, concentrations of cytokines interleukin-9 (IL-9), IL-4 and IL-10 in bronchoalveolar lavage fluid (BALF), serum OVA-specific IgE level, as well as airway inflammation, mucus secretion and collagen deposition in mice. Mechanistically, we investigated the percentages of Th9 cells and Treg cells, as well as mRNA levels of IL-9 and transcription factor Foxp3 in lungs. Furthermore, the proteins expression of nuclear factor-κB (NF-κB) family members p105/p50, RelA, p100/p52 and RelB, as well as mitogen-activated protein kinase (MAPK) family members extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 MAPK was detected. Epimedin C dose-dependently attenuated AHR, airway inflammation, mucus hypersecretion and collagen deposition in OVA-induced murine asthma model. The expression levels of IL-9, IL-4 and OVA-specific IgE were significantly decreased while IL-10 was increased by epimedin C. We further confirmed that epimedin C decreased the percentage of lung Th9 cells with lower mRNA expression of IL-9 and increased the percentage of lung Treg cells with higher mRNA expression of Foxp3. In addition, epimedin C dose-dependently decreased the protein levels of p52, RelB, phosphorylation of ERK1/2 and p38 MAPK which are pivotal to the development of Th9 cells and Treg cells. Collectively, epimedin C could inhibit pathophysiological features of asthma by reconstruction of the balance between Th9 cells and Treg cells through regulation of the noncanonical NF-κB p52/RelB pathway and MAPKs activation. These findings suggest epimedin C as a potential remedy for inflammatory airway diseases.

HIF-2\u03b1 is indispensable for regulatory T cell function

Hypoxia-inducible factor 1α (HIF-1α) and HIF-2α are master transcription factors that regulate cellular responses to hypoxia, but the exact function in regulatory T (Treg) cells is controversial. Here, we show that Treg cell development is normal in mice with Foxp3-specific knockout (KO) of HIF-1α or HIF-2α. However, HIF-2α-KO (but not HIF-1α-KO) Treg cells are functionally defective in suppressing effector T cell-induced colitis and inhibiting airway hypersensitivity. HIF-2α-KO Treg cells have enhanced reprogramming into IL-17-secreting cells. We show crosstalk between HIF-2α and HIF-1α, and that HIF-2α represses HIF-1α expression. HIF-1α is upregulated in HIF-2α-KO Treg cells and further deletion of HIF-1α restores the inhibitory function of HIF-2α-KO Treg cells. Mice with Foxp3-conditional KO of HIF-2α are resistant to growth of MC38 colon adenocarcinoma and metastases of B16F10 melanoma. Together, these results indicate that targeting HIF-2α to destabilize Treg cells might be an approach for regulating the functional activity of Treg cells.

Monocyte-Independent and -Dependent Regulation of Regulatory T-Cell Development in Mycoplasma Infection.

Although Mycoplasma pneumoniae (MP) infection has been implicated in the pathogenesis of allergic diseases, the mechanism of this trigger remains unknown. We explored the mechanism for how MP infection could tilt the balance between regulatory T cells (Tregs) and Th17 cells. We analyzed the frequency, phenotype, and function of Tregs in patients at the different stages of MP and various virus infections over a period of more than 1 year. We examined the effect of monocytes to elucidate signals that can regulate the balance between Treg and Th17 cells. The functional activity of Tregs was profoundly impaired during the acute stage of MP as well as viral infections. Upon resolution, however, the Treg function remained impaired even 1 year after MP infection. In the resolution stage, the impaired Treg function was associated with an increase in interleukin (IL) 17A+ Tregs and Th17 cells. Development of Th17 cells was dependent on the "aberrant" proinflammatory monocytes (pMOs), characterized by potent ability to produce IL-6 in a Toll-like receptor 2-dependent manner. Depending on the prevalence of the pMOs, Tregs and Th17 cells could mutually regulate the number and function of the other. The pMOs/IL-6 could be crucial therapeutic targets against MP-induced allergic diseases.

The Role of MicroRNAs in Development and Function of Regulatory T Cells - Lessons for a Better Understanding of MicroRNA Biology.

MicroRNAs (miRNAs) have emerged as critical posttranscriptional regulators of the immune system, including function and development of regulatory T (Treg) cells. Although this critical role has been firmly demonstrated through genetic models, key mechanisms of miRNA function in vivo remain elusive. Here, we review the role of miRNAs in Treg cell development and function. In particular, we focus on the question what the study of miRNAs in this context reveals about miRNA biology in general, including context-dependent function and the role of individual targets vs. complex co-targeting networks. In addition, we highlight potential technical pitfalls and state-of-the-art approaches to improve the mechanistic understanding of miRNA biology in a physiological context.

A critical role of foxp3a-positive regulatory T cells in maintaining immune homeostasis in zebrafish testis development

Suppressive regulatory T cells (Treg cells) play a vital role in preventing autoimmunity and restraining excessive immune response to both self- and non-self-antigens. Studies on humans and mice show that the Forkhead box p3 (Foxp3) is a key regulatory gene for the development and function of Treg cells. In zebrafish, Treg cells have been identified by using foxp3a as a reliable marker. However, little is known about the function of foxp3a and Treg cells in gonadal development and sex differentiation. Here, we show that foxp3a is essential for maintaining immune homeostasis in zebrafish testis development. We found that foxp3a was specifically expressed in a subset of T cells in zebrafish testis, while knockout of foxp3a led to deficiency of foxp3a-positive Treg cells in the testis. More than 80% of foxp3a–/– mutants developed as subfertile males, and the rest of the mutants developed as fertile females with decreased ovulation. Further study revealed that foxp3a–/– mutants had a delayed juvenile ovary-to-testis transition in definite males and sex reversal in about half of the definite females, which led to a dominance of later male development. Owing to the absence of foxp3a-positive Treg cells in the differentiating testis of foxp3a–/– mutants, abundant T cells and macrophages expand to disrupt an immunosuppressive milieu, resulting in defective development of germ cells and gonadal somatic cells and leading to development of infertile males. Therefore, our study reveals that foxp3a-positive Treg cells play an essential role in the orchestration of gonadal development and sex differentiation in zebrafish.

Transcriptional and translational control of Foxp3+ regulatory T cell functional adaptation to inflammation.

Foxp3+ regulatory T (Treg) cells are the major gatekeepers of the immune system for the maintenance of self-tolerance and immune homeostasis. Treg cell development rests on the key activities of the master-switch transcription factor, Foxp3, which establishes the essential core program that defines Treg cell lineage identity in the thymus and peripheral tissues. Moreover, Foxp3+ Treg cells integrate a variety of inflammatory signals from the tissue microenvironment to engage specialized pathways in order to adapt their suppressive functions in situ. CD4+ Treg cell subsets possess mechanisms to control both gene transcription and mRNA translation. Ultimately, the resulting proteome orchestrates distinct cellular processes that poise Treg cell subsets to respond to inflammatory signals in a timely and context-dependent manner in lymphoid and non-lymphoid tissues for a coordinated modulation of immunity. Thus, understanding how Treg cells control their cellular adaptation in lymphoid and non-lymphoid tissues may reveal therapeutic targets for the treatment of autoimmunity and chronic inflammatory diseases.

All-trans-retinoic acid shifts Th1 towards Th2 cell differentiation by targeting NFAT1 signalling to ameliorate immune-mediated aplastic anaemia.

Severe acquired aplastic anaemia (AA) is a serious disease characterised by autoreactive T cells attacking haematopoietic stem cells, leading to marrow hypoplasia and pancytopenia. Immunosuppressive therapy combined with antithymocyte globulin and ciclosporin can rescue most patients with AA. However, the relapse after ciclosporin withdrawal and the severe side effects of long-term ciclosporin administration remain unresolved. As such, new strategies should be developed to supplement current therapeutics and treat AA. In this study, the possibility of all-trans-retinoic acid (ATRA) as an alternative AA treatment was tested by using an immune-mediated mouse model of AA. Results revealed that ATRA inhibited T-cell proliferation, activation and effector function. It also restrained the Fas/Fasl pathway, shifted Th1 towards Th2 cell development, rebalanced T-cell subsets at a relatively high level and corrected the Th1/Th2 ratio by targeting NFAT1 signalling. In addition, ATRA inhibited Th17 cell differentiation and promoted regulatory T-cell development. Therefore, ATRA was an effective agent to improve AA treatment outcomes.

MKL-1 is a coactivator for STAT5b, the regulator of Treg cell development and function

BackgroundFoxp3+CD4+ regulatory T cells (Treg) constitutes a key event in autoimmune diseases. STAT5b is the critical link between the IL-2/15 and FOXP3, the master regulator of Treg cells.MethodsThe CD3+T cell and Foxp3+CD4+ regulatory T cells were overexpressioned or knockdown MKL-1 and STAT5a and tested for Treg cell development and function. Direct interaction of MKL-1 and STAT5a were analyzed by coimmunoprecipitation assays, Luciferase assay, Immunofluoresence Staining and Yeast two-hybrid screening. The effect of MKL-1 and STAT5a on the Treg genes expression was analyzed by qPCR and western blotting and Flow cytometry.ResultsHowever, the molecular mechanisms mediating STAT5b-dependent Treg genes expression and Treg cell phenotype and function in autoimmune diseases are not well defined. Here, we report that the MKL-1 is a coactivator for the major Treg genes transcription factor STAT5b, which is required for human Treg cell phenotype and function. The N terminus of STAT5b, which contains a basic coiled-coil protein–protein interaction domain, binds the C-terminal activation domain of MKL-1 and enhances MKL-1 mediated transcriptional activation of Treg-specific, CArG containing promoters, including the Treg-specific genes Foxp3. Suppression of endogenous STAT5b expression by specific small interfering RNA attenuates MKL-1 transcriptional activation in cultured human cells. The STAT5b–MKL-1 interaction identifies a role of Treg-specific gene regulation and regulated mouse Treg cell development and function and suggests a possible mechanism for the protective effects of autoimmune disease Idiopathic Thrombocytopenic Purpura (ITP).ConclusionsOur studies demonstrate for the first time that MKL-1 is a coactivator for STAT5b, the regulator of Treg cell development and function.-iyKJXfczyP238CqvjMFToVideo abstract

A Genome-wide CRISPR Screen Reveals a Role for the Non-canonical Nucleosome-Remodeling BAF Complex in Foxp3 Expression and Regulatory T Cell Function

SummaryRegulatory T (Treg) cells play a pivotal role in suppressing auto-reactive T cells and maintaining immune homeostasis. Treg cell development and function are dependent on the transcription factor Foxp3. Here, we performed a genome-wide CRISPR loss-of-function screen to identify Foxp3 regulators in mouse primary Treg cells. Foxp3 regulators were enriched in genes encoding subunits of the SWI/SNF nucleosome-remodeling and SAGA chromatin-modifying complexes. Among the three SWI/SNF-related complexes, the Brd9-containing non-canonical (nc) BAF complex promoted Foxp3 expression, whereas the PBAF complex was repressive. Chemical-induced degradation of Brd9 led to reduced Foxp3 expression and reduced Treg cell function in vitro. Brd9 ablation compromised Treg cell function in inflammatory disease and tumor immunity in vivo. Furthermore, Brd9 promoted Foxp3 binding and expression of a subset of Foxp3 target genes. Our findings provide an unbiased analysis of the genetic networks regulating Foxp3 and reveal ncBAF as a target for therapeutic manipulation of Treg cell function.

Loss of Phosphatidylinositol 3-Kinase Activity in Regulatory T Cells Leads to Neuronal Inflammation

Class I PI3K enzymes are critical for the maintenance of effective immunity. In T cells, PI3Kα and PI3Kδ are activated by the TCR and costimulatory receptors, whereas PI3Kγ is activated by G protein-coupled chemokine receptors. PI3Kδ is a key regulator of regulatory T (Treg) cell function. PI3K isoform-selective inhibitors are in development for the treatment of diseases associated with immune dysregulation, including chronic inflammatory conditions, cancer, and autoimmune diseases. Idelalisib (PI3Kδ), alpelisib (PI3Kα), duvelisib (PI3Kδ/γ), and copanlisib (pan-PI3K) have recently been approved for use in cancer treatment. Although effective, these therapies often have severe side effects associated with immune dysregulation and, in particular, loss of Treg cells. Therefore, it is important to gain a better understanding of the relative contribution of different PI3K isoforms under homeostatic and inflammatory conditions. Experimental autoimmune encephalitis is a mouse model of T cell-driven CNS inflammation, in which Treg cells play a key protective role. In this study, we show that PI3Kδ is required to maintain normal Treg cell development and phenotype under homeostatic conditions but that loss of PI3Kδ alone in Treg cells does not lead to autoimmunity. However, combined loss of PI3Kα and PI3Kδ signaling resulted in increased experimental autoimmune encephalitis disease severity. Moreover, mice lacking PI3Kα and PI3Kδ in Treg cells developed spontaneous peripheral nerve inflammation. These results show a key role for PI3K signaling in Treg cell-mediated protection against CNS inflammation.

Mouse Double Minute 2 Homolog-Mediated Ubiquitination Facilitates Forkhead Box P3 Stability and Positively Modulates Human Regulatory T Cell Function.

Regulatory T cells (Treg cells) are essential for maintaining immune tolerance, and the dysfunction of Treg cells may cause autoimmune diseases and tumors. Forkhead box P3 (FOXP3) is the key transcription factor controlling Treg cell development and suppressive function. Mouse double minute 2 homolog (MDM2), an E3 ubiquitin ligase, has been identified as an oncoprotein that mediates the ubiquitination and degradation of tumor suppressor p53; however, whether it has functions in Treg cells remains unknown. Here, we demonstrate that MDM2 positively regulates human Treg cell suppressive function via its mediated ubiquitination and stabilization of FOXP3. Knockdown of MDM2 with shRNA in human primary Treg cells leads to the impaired ability of FOXP3 to regulate the expression levels of downstream genes and the attenuated suppressive capacity of Treg cells, due to FOXP3 instability. Consistently, MDM2 overexpression in human Treg cells enhances FOXP3 stability and Treg cell suppressive capacity. Mechanistically, MDM2 interacts with FOXP3, and mainly mediates monoubiquitination and polyubiquitination of FOXP3, thus stabilizing the protein level of FOXP3. We have also found lysine residues in FOXP3 required for MDM2-mediated ubiquitination. In addition, TCR/CD28 signaling upregulates the expression level of MDM2 and its mediated FOXP3 ubiquitination in human Treg cells. Therefore, our findings reveal that MDM2 in Treg cells could be a potential therapeutic target for treating autoimmune diseases and tumors.

Genetics Meets Epigenetics in Treg Cells and Autoimmunity

Most autoimmunity-associated SNPs in the genome map to noncoding regulatory regions in Tcells, but the nature of underlying epigenetic mechanisms and any normal purpose in Tcell differentiation remain unclear. In this issue of Immunity, Ohkura etal. establish that crucial SNPs linked to autoimmune disease are enriched in DNA regions of CpG demethylation that govern Treg cell development and function.

Gut Microbial Metabolites Induce Donor-Specific Tolerance of Kidney Allografts through Induction of T Regulatory Cells by Short-Chain Fatty Acids.

Short-chain fatty acids derived from gut microbial fermentation of dietary fiber have been shown to suppress autoimmunity through mechanisms that include enhanced regulation by T regulatory cells (Tregs). Using a murine kidney transplantation model, we examined the effects on alloimmunity of a high-fiber diet or supplementation with the short-chain fatty acid acetate. Kidney transplants were performed from BALB/c(H2d) to B6(H2b) mice as allografts in wild-type and recipient mice lacking the G protein-coupled receptor GPR43 (the metabolite-sensing receptor of acetate). Allograft mice received normal chow, a high-fiber diet, or normal chow supplemented with sodium acetate. We assessed rejection at days 14 (acute) and 100 (chronic), and used 16S rRNA sequencing to determine gut microbiota composition pretransplantation and post-transplantation. Wild-type mice fed normal chow exhibited dysbiosis after receiving a kidney allograft but not an isograft, despite the avoidance of antibiotics and immunosuppression for the latter. A high-fiber diet prevented dysbiosis in allograft recipients, who demonstrated prolonged survival and reduced evidence of rejection compared with mice fed normal chow. Allograft mice receiving supplemental sodium acetate exhibited similar protection from rejection, and subsequently demonstrated donor-specific tolerance. Depletion of CD25+ Tregs or absence of the short-chain fatty acid receptor GPR43 abolished this survival advantage. Manipulation of the microbiome by a high-fiber diet or supplementation with sodium acetate modified alloimmunity in a kidney transplant model, generating tolerance dependent on Tregs and GPR43. Diet-based therapy to induce changes in the gut microbiome can alter systemic alloimmunity in mice, in part through the production of short-chain fatty acids leading to Treg cell development, and merits study as a potential clinical strategy to facilitate transplant acceptance.

Autocrine TGF-β1 Maintains the Stability of Foxp3+ Regulatory T Cells via IL-12Rβ2 Downregulation.

Transforming growth factor beta 1 (TGF-β1) is an immunosuppresive cytokine that plays an essential role in immune homeostasis. It is well known that regulatory T (Treg) cells express TGF-β1; however, the role of autocrine TGF-β1 in the development, function, and stability of Treg cells remains poorly understood. We found that Treg cell-derived TGF-β1 was not required for the development of thymic Treg cells in mice, but played a role in the expression of latency-associated peptide and optimal suppression of naïve T cell proliferation in vitro. Moreover, the frequency of Treg cells was significantly reduced in the mesenteric lymph nodes of the Treg cell-specific TGF-β1-deficient mice, which was associated with increased frequency of IFN-γ-producers among Treg cells. TGF-β1-deficient Treg cells were more prone to express IFN-γ than TGF-β1-sufficient Treg cells in a dendritic cell-mediated stimulation in vitro as well as in an adoptive transfer study in vivo. Mechanistically, TGF-β1-deficient Treg cells expressed higher levels of Il12rb2 and were more sensitive to IL-12-induced conversion into IFN-γ-producing Treg cells or IFN-γ-producing exTreg cells than TGF-β1-sufficient Treg cells. Our findings demonstrate that autocrine TGF-β1 plays a critical role in the optimal suppressive activity and stability of Treg cells by downregulating IL-12R on Treg cells.

Regulating T-cell differentiation through the polyamine spermidine

The cross-talk between the host and its microbiota plays a key role in the promotion of health. The production of metabolites such as polyamines by intestinal-resident bacteria is part of this symbiosis shaping host immunity. The polyamines putrescine, spermine, and spermidine are abundant within the gastrointestinal tract and might substantially contribute to gut immunity. We aimed to characterize the polyamine spermidine as a modulator of T-cell differentiation and function. Naive T cells were isolated from wild-type mice or cord blood from healthy donors and submitted to polarizing cytokines, with and without spermidine treatment, to evaluate CD4+ T-cell differentiation invitro. Moreover, mice were subjected to oral supplementation of spermidine, or its precursor l-arginine, to assess the frequency and total numbers of regulatory T (Treg) cells invivo. Spermidine modulates CD4+ T-cell differentiation invitro, preferentially committing naive T cells to a regulatory phenotype. After spermidine treatment, activated T cells lacking the autophagy gene Atg5 fail to upregulate Foxp3 to the same extent as wild-type cells. These results indicate that spermidine's polarizing effect requires an intact autophagic machinery. Furthermore, dietary supplementation with spermidine promotes homeostatic differentiation of Treg cells within the gut and reduces pathology in a model of T-cell transfer-induced colitis. Altogether, our results highlight the beneficial effects of spermidine, or l-arginine, on gut immunity by promoting Treg cell development.

Type 2 immunity in the skin and lungs.

There has been extensive progress in understanding the cellular and molecular mechanisms of inflammation and immune regulation in allergic diseases of the skin and lungs during the last few years. Asthma and atopic dermatitis (AD) are typical diseases of type 2 immune responses. interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin are essential cytokines of epithelial cells that are activated by allergens, pollutants, viruses, bacteria, and toxins that derive type 2 responses. Th2 cells and innate lymphoid cells (ILC) produce and secrete type 2 cytokines such as IL-4, IL-5, IL-9, and IL-13. IL-4 and IL-13 activate B cells to class-switch to IgE and also play a role in T-cell and eosinophil migration to allergic inflammatory tissues. IL-13 contributes to maturation, activation, nitric oxide production and differentiation of epithelia, production of mucus as well as smooth muscle contraction, and extracellular matrix generation. IL-4 and IL-13 open tight junction barrier and cause barrier leakiness in the skin and lungs. IL-5 acts on activation, recruitment, and survival of eosinophils. IL-9 contributes to general allergic phenotype by enhancing all of the aspects, such as IgE and eosinophilia. Type 2 ILC contribute to inflammation in AD and asthma by enhancing the activity of Th2 cells, eosinophils, and their cytokines. Currently, five biologics are licensed to suppress type 2 inflammation via IgE, IL-5 and its receptor, and IL-4 receptor alpha. Some patients with severe atopic disease have little evidence of type 2 hyperactivity and do not respond to biologics which target this pathway. Studies in responder and nonresponder patients demonstrate the complexity of these diseases. In addition, primary immune deficiency diseases related to T-cell maturation, regulatory T-cell development, and T-cell signaling, such as Omenn syndrome, severe combined immune deficiencies, immunodysregulation, polyendocrinopathy, enteropathy, X-linked syndrome, and DOCK8, STAT3, and CARD11 deficiencies, help in our understanding of the importance and redundancy of various type 2 immune components. The present review aims to highlight recent advances in type 2 immunity and discuss the cellular sources, targets, and roles of type 2 mechanisms in asthma and AD.

MicroRNA-92a controls the balance between inflammatory and regulatory T cells in CNS autoimmunity

Abstract Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are mediated by dysregulated autoreactive T cell responses in the central nervous system (CNS). This dysregulation consists of an imbalance between inflammatory T helper cells, such as Th17 cells, and Foxp3+ T regulatory cells (Tregs). MicroRNAs (miRNAs), a class of small non-coding RNAs, are known to play a key role in immune function, and to be dysregulated in EAE and MS. However, identifying specific miRNA pathways that directly connect clinical activity with immune mechanisms in CNS autoimmunity has been a challenge. Previous work has identified miR-92a as one of the most significantly elevated miRNAs in the sera of MS patients, which positively correlates with neurological symptoms and brain atrophy. We now report a major functional role for miR-92a in CNS autoimmunity. MiR-92a is increased during EAE, and its loss strikingly attenuates clinical disease. This attenuation is accompanied by reduced Th17 and increased Treg cells in the CNS. Mechanistically, we found that T cell-intrinsic miR-92a inhibits the development and function of Treg cells while promoting those of Th17 cells by targeting Foxo1, a key transcription factor in T helper cell biology. Preclinical administration of miR-92a inhibitor phenocopies miR-92a loss and ameliorates EAE. Analogous to mice, miR-92a is significantly elevated in MS patient T cells, and reciprocally regulates human Treg and Th17 differentiation. These findings suggest miR-92a skews the Treg/Th17 balance to promote CNS autoimmunity, and that miR-92a silencing may be of therapeutic benefit for MS patients.

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.

FOXP3 promotes colorectal carcinoma liver metastases by evaluating MMP9 expression via regulating S-adenosylmethionine metabolism.

BackgroundGrowing evidence has proved that Forkhead box protein 3 (FOXP3), which is a master regulatory gene in the development and function of regulatory T-cells, is expressed in human cancer cells. This expression indicates the crucial role FOXP3 takes up as the disease progresses. However, its role in colorectal cancer (CRC) liver metastasis is still mostly unknown. This study set out to explore the molecular characteristics of FOXP3 in driving the liver metastasis within CRC.MethodsWe downloaded the RNA-seq data from the GSE50760. Weighted gene co-expression network analysis (WGCNA)WGCNA and RNA-Seq analysis were applied to find the key gene network associated with colorectal cancer liver metastasis. Then we performed pathway enrichment analysis on liver metastasis-associated gene set. Immunohistochemistry, in vitro and in vivo studies were conducted to test expression and function of FOXP3 in CRC tissues and liver metastasis tissues. Non-targeted metabolomics analysis was performed to identify the alteration of FOXP3 expression in metabolites of colorectal cancer liver metastasis. Western blot was performed to confirm changes of matrix metalloproteinase 9MMP9 expression were downstream events of S-adenosyl-methionine (SAM).ResultsWe found that FOXP3 and MMP9 exhibited co-expression relationships and affected liver metastasis in CRC. Upregulation of FOXP3 promotes cell migration and invasion in CRC, which suggests a pro-cancer effect. Moreover, metabolomics analysis showed that knockdown of FOXP3 significantly reduced SAM levels, and changes of MMP9 expression were downstream events of SAM, which is concentration-dependent. Besides, The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Western blot analysis confirmed that overexpression of FOXP3 activates the Wnt pathway to promote colon cancer metastasis.ConclusionsOur results altogether suggested that FOXP3 expression inhibited the SAM cycle to reduce SAMe levels, resulting in altered MMP9 expression and helped CRC liver metastasis.