Treg Induction Research Articles

IL-33 Orchestrated the Interaction and Immunoregulatory Functions of Alternatively Activated Macrophages and Regulatory T Cells InVitro.

Our group has previously demonstrated elevated serum-soluble ST2 in patients with active systemic lupus erythematosus, suggesting a role of IL-33 in the underlying pathogenesis. However, inconsistent results have been reported on the effect of exogenous IL-33 on murine lupus activity, which may be mediated by concerted actions of various immune cells invivo. This study aimed to examine the function of IL-33 on macrophage polarization and regulatory T cells (Treg) and their interactive effects in the lupus setting by invitro coculture experiments of macrophages and T cells that were performed in the presence or absence of IL-33-containing medium. Compared to IL-4-polarized bone marrow-derived macrophages (BMDM) from MRL/MpJ mice, adding IL-33 enhanced mRNA expression of markers of alternatively activated macrophages, including CD206 and Arg1. IL-33 and IL-4 copolarized BMDM produced higher TGF-β but not IL-6 upon inflammatory challenge. These BMDM induced an increase in the Foxp3+CD25+ Treg population in cocultured allogeneic T cells from MRL/MpJ and predisease MRL/lpr mice. These copolarized BMDM also showed an enhanced suppressive effect on T cell proliferation with reduced IFN-γ and IL-17 release but increased TGF-β production. In the presence of TGF-β and IL-2, IL-33 also directly promoted inducible Treg that expressed a high level of CD25 and more sustained Foxp3. Unpolarized BMDM cocultured with these Treg displayed higher phagocytosis. In conclusion, TGF-β was identified as a key cytokine produced by IL-4 and IL-33 copolarized alternatively activated macrophages and the induced Treg, which may contribute to a positive feedback loop potentiating the immunoregulatory functions of IL-33.

Identification of human exTreg cells as CD16+CD56+ cytotoxic CD4+ T cells.

In atherosclerosis, some regulatory T (Treg) cells become exTreg cells. We crossed inducible Treg and exTreg cell lineage-tracker mice (FoxP3eGFP-Cre-ERT2ROSA26CAG-fl-stop-fl-tdTomato) to atherosclerosis-prone Apoe-/- mice, sorted Treg cells and exTreg cells and determined their transcriptomes by bulk RNA sequencing (RNA-seq). Genes that were differentially expressed between mouse Treg cells and exTreg cells and filtered for their presence in a human single-cell RNA-sequencing (scRNA-seq) panel identified exTreg cell signature genes as CST7, NKG7, GZMA, PRF1, TBX21 and CCL4. Projecting these genes onto the human scRNA-seq with CITE-seq data identified human exTreg cells as CD3+CD4+CD16+CD56+, which was validated by flow cytometry. Bulk RNA-seq of sorted human exTreg cells identified them as inflammatory and cytotoxic CD4+T cells that were significantly distinct from both natural killer and Treg cells. DNA sequencing for T cell receptor-β showed clonal expansion of Treg cell CDR3 sequences in exTreg cells. Cytotoxicity was functionally demonstrated in cell killing and CD107a degranulation assays, which identifies human exTreg cells as cytotoxic CD4+T cells.

The immunosuppression effects of deforolimus (ridaforolimus, AP23573) on allograft organ transplantation

AbstractObjectsWe conducted this study to confirm the immunosuppression effect of Deforolimus in heart allotransplantation and find its mechanism.Material and methodsWe used vitro methods to confirm the immunosuppression of Deforolimus in T cell subgroups. Then, we conducted heart allotransplantation from BALB/c donors to C57BL/6 recipients with the oral administration of Deforolimus or blank solvent to contrast the immunosuppression effect in vivo. We used the flow cytometry（）, clone anergy test, ELISA (enzyme‐linked immunosorbent assay), apoptosis test, and lymphocyte translation (LT) to find the mechanism of Deforolimus’ immunosuppressive action.ResultsStudies in vitro demonstrated that Deforolimus had immunosuppressive action. Studies in vivo demonstrated that Deforolimus could inhibit the immune system of the heart allotransplantation recipients to extend the recipients’ life. The mechanisms of Deforolimus’ immunosuppressive action included induction of Tregs (regulatory T cells), induction of T cells anergy, and decreasing proportion of T cells in spleens and lymph nodes.ConclusionDeforolimus suppressed the immunological rejection of mouse cardiac allotransplantation which laid the foundation of Deforolimus applying to solid organ allotransplantation.

Recruitment of myeloid‑derived suppressor cells and regulatory T‑cells is associated with the occurrence of acute myocardial infarction.

The roles of myeloid-derived suppressor cells (MDSCs) and regulatory T-cells (Tregs) in acute myocardial infarction (AMI) remain elusive. The present study aimed to analyze the proportions of the granulocytic and monocytic populations of MDSCs (G-MDSCs and M-MDSCs, respectively), and Tregs in the peripheral blood mononuclear cells (PBMCs) of patients with AMI. The present study recruited 34 patients with AMI and 37 healthy controls without clinical signs of myocardial ischemia. PBMCs were isolated from the peripheral blood samples of patients with AMI within 24 h following admission to the hospital and from those of the healthy controls during a physical examination. Two subsets of MDSCs, G-MDSCs (CD15+CD33+CD11b+CD14-HLA-DRlow) and M-MDSCs (CD14+CD15-CD11b+HLA-DRlow), and Tregs (CD3+CD4+CD25highCD127low T-cells) in the PBMCs derived from the patients with AMI and healthy controls were analyzed using flow cytometry. The effects of MDSCs derived from patients with AMI on naïve CD4+ T-cells were examined in the co-culture system. The results revealed that the proportions of G-MDSCs and M-MDSCs were higher in the peripheral blood of patients with AMI than in that of the healthy controls. The patients with AMI had significantly higher numbers of programmed death-ligand (PD-L)1- and PD-L2-positive G-MDSCs and M-MDSCs compared with the healthy controls (P<0.05). The MDSCs could acquire a granulocytic phenotype following AMI, and the G-MDSCs and M-MDSCs would be more likely to express PD-L2 and PD-L1, respectively. The ratios of Tregs to CD4+ T-cells and PD-1+ Tregs in the peripheral blood of patients with AMI were significantly higher than those in the healthy controls (P<0.05). The results of flow cytometry demonstrated an increase in the numbers of inducible Tregs in the co-culture system with the G-MDSCs derived from patients with AMI compared with the G-MDSCs derived from the healthy controls (P<0.01). On the whole, the findings presented herein demonstrate the accumulation of MDSCs, and the upregulation of PD-L1 and PD-L2 expression on the surface of MDSCs in patients with AMI. MDSCs can induce the expansion of Tregs by binding PD-1 on the surface of Tregs, thus playing a crucial role in AMI.

Defective Treg generation and increased type 3 immune response in leukocyte adhesion deficiency 1

In 15 Turkish LAD-1 patients and controls, we assessed the impact of pathogenic ITGB2 mutations on Th17/Treg differentiation and functions, and innate lymphoid cell (ILC) subsets.The percentage of peripheral blood Treg cells, in vitro-generated induced Tregs differentiated from naive CD4+ T cells were decreased despite the elevated absolute counts of CD4+ cells in LAD-1 patients. Serum IL-23 levels were elevated in LAD-1 patients. Post-curdlan stimulation, LAD-1 patient-derived PBMCs produced more IL-17A. Additionally, the percentages of CD18-deficient Th17 cells expanded from total or naïve CD4+ T cells were higher. The blood ILC3 subset was significantly elevated in LAD-1. Finally, LAD-1 PBMCs showed defects in trans-well migration and proliferation and were more resistant to apoptosis.Defects in de novo generation of Tregs from CD18-deficient naïve T cells and elevated Th17s, and ILC3s in LAD-1 patients' peripheral blood suggest a type 3-skewed immunity and may contribute to LAD-1-associated autoimmune symptoms.

Therapeutic properties of Helicobacter pylori-derived vacuolating cytotoxin A in an animal model of chronic allergic airway disease

BackgroundIt has previously been shown that the Helicobacter pylori (H. pylori)-derived molecule vacuolating cytotoxin A (VacA) could be suitable for the treatment of allergic airway disease. The therapeutic activity of the protein, which acts through modulation of dendritic cells (DC) and regulatory T cells (Tregs), was demonstrated in murine short-term acute models. The aim of this study is to further evaluate the therapeutic potential of VacA by determining the effectiveness of different application routes and the suitability of the protein for treating the chronic phase of allergic airway disease.MethodsVacA was administered by the intraperitoneal (i.p.), oral (p.o.) or intratracheal (i.t.) routes, and long-term therapeutic effectiveness, allergic airway disease hallmarks, and immune phenotype were analyzed in murine models of acute and chronic allergic airway disease.ResultsAdministration of VacA via the i.p., p.o or i.t. routes was associated with a reduction in airway inflammation. The i.p. route showed the most consistent effect in reducing airway inflammation and i.p. treatment with VacA was the only treatment that significantly reduced mucus cell hyperplasia. In a murine model of chronic allergic airway disease, both short- and long-term treatment with VacA showed a therapeutic effect, with a reduction in a variety of asthma hallmarks, including bronchoalveolar lavage eosinophilia, lung inflammation and goblet cell metaplasia. Short-term treatment was associated with induction of Tregs, while repetitive long-term administration of VacA influenced immunological memory in the lung.ConclusionsIn addition to showing therapeutic efficacy in short-term models, treatment with VacA also appeared to be effective in suppressing inflammation in a chronic airway disease model. The observation that treatment was effective after administration via several different routes highlights the potential of VacA as a therapeutic agent with different routes of administration in humans.

Immunotherapy Targeting CCR8+ Regulatory T Cells Induces Antitumor Effects via Dramatic Changes to the Intratumor CD8+ T Cell Profile.

Regulatory T cells (Tregs) contribute to the formation of a tumor-immunosuppressive microenvironment. CCR8 is reportedly selectively expressed in tumor Tregs, and an anti-CCR8 Ab can exert potent antitumor effects by eliminating intratumor Tregs in murine tumor models. In this study, we analyzed changes to intratumor immunity after anti-CCR8 Ab administration, especially in CD8+ T cells, which are involved in cancer cell killing, using the CT26 colorectal carcinoma mouse model. Immunophenotyping of tumor-infiltrating cells by mass cytometry after Ab administration on day 5 of tumor inoculation revealed that CD8+ T cell subsets were dramatically altered in the CCR8 Ab-treated group, with an increase in naive cells and nonexhausted effector cells and a decrease in exhausted cells with high expression levels of TOX. These results were corroborated with flow cytometry analysis. Delayed administration of the anti-CCR8 Ab on day 9 or 12, when the amount of CCR8+ Tregs and CD8+ T cell exhaustion were more progressed, also resulted in a decrease in exhausted CD8+ T cells, leading to tumor regression. Finally, we confirmed that high CCR8+ Treg infiltration was associated with high TOX expression in CD8+ T cells in human cancer patients. In conclusion, administration of an anti-CCR8 Ab can dramatically alter the activation and exhaustion state of intratumor CD8+ T cells, resulting in strong antitumor effects. In cancer patients with an advanced tumor-immunosuppressive environment, CD8+ T cell exhaustion has progressed along with CCR8+ Treg induction. Therefore, targeted depletion of CCR8+ Tregs is expected to be effective in these patients.

Exosomes from Adipose Tissue-derived Mesenchymal Stem Cells Induce Regulatory T Cells in COVID-19 Patients.

An imbalance between regulatory T (Treg) and T-helper (Th)-17 cells has been implicated in the pathogenesis of coronavirus disease 2019 (COVID-19). Mesenchymal stem cells (MSCs) exert immunomodulatory properties through secreting exosomes. This study aimed to assess the effect of MSC-derived exosomes (MSC-Exo) on the differentiation of peripheral blood mononuclear cells (PBMCs) into Tregs from patients with COVID-19. Exosomes were isolated from adipose tissue-derived MSCs. PBMCs were separated from the whole blood of COVID-19 patients (n=20). Treg frequency was assessed before and 48 hours after treatment of PBMCs with MSC-Exo using flow cytometry. Expression of FOXP3 and cytokine genes, and the concentration of cytokines associated with Tregs, were assessed before and after treatment with MSC-Exo. The frequency of CD4+CD25+CD127- Tregs was significantly higher after treating PBMCs with MSC-Exo (6.695±2.528) compared to before treatment (4.981±2.068). The expressions of transforming growth factor (TGF)-β1, interleukin (IL)-10, and FOXP3 were significantly upregulated in MSC-Exo-treated PBMCs. The concentration of IL-10 increased significantly after treatment (994.7±543.9 pg/mL) of PBMCs with MSC-Exo compared with before treatment (563.5±408.6 pg/mL). The concentration of TGF-β was significantly higher in the supernatant of PBMCs after treatment with MSC-Exo (477.0±391.1 pg/mL) than PBMCs before treatment(257.7±226.3 pg/mL). MSC-Exo has the potential to raise anti-inflammatory responses by induction of Tregs, potentiating its therapeutic effects in COVID-19.

Arginine-Rich Cell-Penetrating Peptide-Mediated Transduction of Mouse Nasal Cells with FOXP3 Protein Alleviates Allergic Rhinitis.

Intranasal corticosteroids are effective medications against allergic rhinitis (AR). However, mucociliary clearance promptly eliminates these drugs from the nasal cavity and delays their onset of action. Therefore, a faster, longer-lasting therapeutic effect on the nasal mucosa is required to enhance the efficacy of AR management. Our previous study showed that polyarginine, a cell-penetrating peptide, can deliver cargo to nasal cells; moreover, polyarginine-mediated cell-nonspecific protein transduction into the nasal epithelium exhibited high transfection efficiency with minimal cytotoxicity. In this study, poly-arginine-fused forkhead box P3 (FOXP3) protein, the "master transcriptional regulator" of regulatory T cells (Tregs), was administered into the bilateral nasal cavities of the ovalbumin (OVA)-immunoglobulin E mouse model of AR. The effects of these proteins on AR following OVA administration were investigated using histopathological, nasal symptom, flow cytometry, and cytokine dot blot analyses. Polyarginine-mediated FOXP3 protein transduction induced Treg-like cell generation in the nasal epithelium and allergen tolerance. Overall, this study proposes FOXP3 activation-mediated Treg induction as a novel and potential therapeutic strategy for AR, providing a potential alternative to conventional intranasal drug application for nasal drug delivery.

Development of a CCR8 monoclonal antibody to block CCR8 signaling and to abolish the immunosuppressive function of Treg for the treatment of cancers.

e14506 Background: The tumor microenvironment (TME) contains regulatory T (Treg) cells, which play a critical role in immunosuppression and are thus an attractive target for cancer therapy. The ideal approach would be to inhibit Tregs within tumors while sparing those in peripheral and normal tissues. Tumor-associated Tregs express the chemokine receptor CCR8, which is involved in the induction, expansion, migration, and immunosuppression of Tregs, making targeted inhibition of CCR8 signaling a potential therapeutic strategy against cancer. Methods: We have developed IPG0521, a monoclonal antibody antagonist of CCR8, and characterized its properties, including signaling blocking, chemotaxis, species cross-reactivity, anti-tumor efficacy, and synergistic antitumor effect with PD1 antibody. Single-cell RNA sequencing with CD45+ cells isolated from tumors treated with or without IPG0521 was also employed for profiling the mechanism of the antitumor effect of IPG0521 in the murine H22 cancer model. Results: IPG0521 inhibits receptor-mediated signaling and chemotaxis in Treg cells with a single-digit nanomolar IC50. It is cross-reactive in five species: mouse, rat, dog, monkey, and human. IPG0521 has shown excellent anti-tumor efficacy in several murine syngeneic cancer models, and its anti-tumor effect is enhanced when combined with a PD-1 antibody. Its sustained anti-tumor efficacy has been demonstrated in the murine H22 cancer model via even withdrawing the antibody during the study. The results of deep single-cell RNA sequencing on tumor-infiltrating lymphocytes (TILs) showed that the transcriptional profiles of these Treg cells could be distinguished into three distinct subsets based on molecular, functional, and immunosuppressive properties. These subsets were defined as the Treg_Foxp3 high subset, which exhibited low immunosuppression, the Treg_Foxp3 mild subset, which demonstrated mild immunosuppression, and the Treg_Foxp3 low subset, which had high proliferation. IPG0521 treatment resulted in a significant increase in the Treg_ Foxp3 high subset and a significant decrease in the Treg _ Foxp3 mild subset while no change in the Treg_ Foxp3 low subset, indicating a reduction in Treg immunosuppression. This change in Treg cells also altered the composition of other immune cells, including a significant increase in neutrophils and natural killer (NK) cells, which ultimately inhibited tumor growth. Conclusions: IPG0521 has potent anti-tumor effects in multiple tumor types, including lung, liver, and breast cancers, in both syngeneic and immune-humanized mouse models. It inhibits Tregs immunosuppression and activates CD8+ T cells to achieve its anti-tumor effects. These results support the development of IPG0521, which is currently under IND filing, as a novel therapeutic agent for the treatment of cancers.

Astragalus Polysaccharide Mediates Immunomodulatory Effects on Crosstalk between Human Peripheral Blood Mononuclear Cells and Ovarian Cancer Cell Line.

Astragalus polysaccharide (APS) is a functional component of Astragalus membranaceus with antitumor and immunomodulatory properties. This study evaluated the effect of APS on the peripheral blood mononuclear cell (PBMC) proliferation, cytokine secretion, and regulatory T cell (Treg) induction in an in vitro coculture model of human PBMCs and A2780 human ovarian cancer cells. PBMC proliferation and Treg frequency were measured by flow cytometry. Cytokine levels were assessed by enzyme-linked immunosorbent assay. APS significantly enhanced the PBMC proliferation, reduced Treg frequency, decreased anti-inflammatory cytokines including interleukin [IL]-10, transforming growth factor beta (TGF-β), and vascular endothelial growth factor-A (VEGF-A), and increased the pro-inflammatory cytokine IL-6. These findings suggest that APS may be an effective immunomodulatory supplement for cancer therapy, particularly for ovarian cancer by enhancing antitumor immune responses.

Zinc Treated Engineered Human Dendritic Cells Capable of Synthesizing High Active Vitamin D and Retinoic Acid Concentrations Enhance Gut-homing Regulatory T Cell Induction

Abstract Inflammatory bowel disease (IBD) is a chronic inflammatory disorder in the gastrointestinal tract (the Gut). Available IBD therapies can cause severe side effects, and many patients either fail to respond to the treatment or lose therapeutic effects with time. Hence, IBD therapy is still an unmet medical need. We recently proposed to enhance the induction of regulatory T cells (Tregs) expressing gut-homing molecules (gut-homing Tregs) to control chronic gut inflammation in IBD patients without compromising systemic immunity. We have shown that dendritic cells (DCs), engineered to de novo synthesize high concentrations of the active vitamin D (1,25-dihydroxy vitamin D or 1,25[OH]2D) and retinoic acid, increase the induction of gut-homing Tregs phenotypically and functionally in healthy mice and the mice induced for experimental colitis. This current study investigated whether the engineered DCs worked in humans. In addition, we also asked how zinc impacts the function of our engineered DCs because zinc is a biologically essential mineral widely included in daily supplements and has also been shown to tolerize DCs. Our data showed that the engineered DCs, derived from healthy control subjects and IBD patients, stimulated autologous naïve CD4+ T cells to express both regulatory and gut-homing molecules (gut-homing Tregs). In addition, the stimulated CD4+ T cells suppressed the proliferation of autologous effector T cells. Moreover, the addition of zinc enhanced the ability of the engineered human DCs to augment the induction of autologous gut-homing Tregs. Hence, our findings indicate zinc-treated engineered DCs are a promising novel IBD therapy. This study was partially supported by the AAI Careers in Immunology Fellowship; the US Army Medical Research and Materiel Command grant (W81XWH-15-0240); and the GI Foundation of Loma Linda University Innovation grant (RIG-GI 681207-2967).

Essential role of IL-17A in activating Treg cells in autoimmune uveitis

Abstract The balance between Th17 cells and regulatory T (Treg) cells is critical for host homeostasis. The signature cytokine of Th17 cells, IL-17A, is a pro-inflammatory cytokine associated with various autoimmune diseases in patients and in animal models. Our previous study demonstrated that IL-17A limits pathogenicity of Th17 cells by inducing IL-24. In this study, we investigate the role of IL-17A in regulating Treg cells. In-vitro studies showed that IL-17A promotes both the differentiation and suppressive functions of Treg cells. Adoptive transfer of IL-17A-treated Treg cells is more potent to ameliorate experimental autoimmune uveitis (EAU) in mice when compared to the control Treg cells. We found that the induction of Treg cells is impaired in Il17ra −/−mice after EAU immunization and Il17ra −/−naïve T cells are less effective in their differentiation into Treg cells in EAU compared to wild-type cells. Mechanistic studies revealed that IL-17A activates NF-kB signaling and inhibits TAZ, a Foxp3 suppressor, during Treg cell differentiation. In conclusion, our data suggest that IL-17A is involved in Tregs induction and/or maintenance, and that this has a role in controlling the autoimmune response. Natural Science Foundation of Guangdong Province (2019A1515010956, 2021A1515010569, 2022A1515012450) Fundamental Research Fund of the State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center.

Prophylactic and therapeutic use of synthetically glycosylated antigens to limit allergic airway disease

Abstract Asthma is a disease involving chronic airway inflammation affecting more than 300 million people worldwide. There is currently no cure for asthma. While effective, corticosteroids cause broad immune suppression and long-term debilitating disease. Novel immune modulatory therapeutics leave patients vulnerable to infections. Therefore, there is a current need for new therapeutics that target the underlying causes of the disease without triggering detrimental side effects. Through synthetic glycosylation, our platform targets hepatic antigen presenting cells and leverages the liver’s tolerance-inducing mechanisms to limit inflammatory T cell responses, while promoting regulatory T cell (Treg) responses, thus preventing broad immunosuppression. In a model of experimental allergic airway inflammation, prophylactic treatment with synthetically mannosylated OVA (pMan OVA) ameliorated the allergic response to inhaled OVA. Our treatment reduced lung and airway eosinophilia, systemic levels of IgE and OVA-specific IgG1, and airway mucus. Furthermore, pMan OVAtreatment reduced OVA specific lung T H2 cells, and exhibited reduced production of IL-4, IL-5 and IL-13 upon antigen specific restimulation. Treatment with pMan OVAwas accompanied by induction of OVA-specific Tregs, which negatively correlated with features of allergic airway disease. In previously sensitized mice, therapeutic intervention with pMan OVAreduced airway and lung eosinophilia, B cell and CD4 +T cell inflammation. Altogether, these data suggest a potential role for prophylactic and therapeutic intervention with synthetically glycosylated allergens in ameliorating disease severity in a model of allergic airway inflammation.

Gut microbiome-derived isodeoxycholic acid promotes mucosal immune non-responsiveness

Abstract Perturbations to the commensal gut microbiota are associated with the increasing prevalence of food allergies. Our lab has reported that colonization of germ-free mice with feces from healthy, but not cow’s milk allergic, infants protects against anaphylaxis to a cow’s milk allergen. Protection was associated with higher levels of the secondary bile acid (SBA) isodeoxycholic acid (isoDCA) in the feces of healthy-colonized mice. IsoDCA has been reported to induce regulatory T cells (Tregs) which suppress inflammation. We hypothesize that isoDCA-driven induction of mucosal Tregs promotes non-responsiveness and protects against food allergy. To study this, we identified two Clostridiaspecies, Peptacetobacter hiranonisand Ruminococcus gnavus, that together produce isoDCA from taurocholic acid (TCA), an abundant host bile acid. Using a Group II intron-based system, we engineered R. gnavus Δrumgna_00694, a functional knock-out of a 3β-hydroxysteroid dehydrogenase required to produce isoDCA. In our system, P. hiranonisconverts TCA to deoxycholic acid (DCA) and R. gnavusWT, but not Δrumgna_00694, converts DCA to isoDCA. Ongoing experiments will compare isoDCA-dependent Treg induction in gut-associated lymphoid tissues of mice co-colonized with P. hiranonisand R. gnavusWT or Δrumgna_00694. Once optimized, this system can be used in our allergic sensitization model to investigate the role of SBA in protection against food allergy and maintenance of intestinal homeostasis.

Premature Treg induction in early life results in FoxP3 instability post-weaning

Abstract Peripherally-derived RORγt+ regulatory T cells (Tregs) induced in early life are crucial for maintaining oral tolerance later in life, and the loss of these long-lived cells is associated with increased allergic and inflammatory phenotypes in several animal models. We have identified a predominant pathway of luminal antigen delivery that is associated with Treg development. Around weaning, microbial and dietary proteins are delivered to the colonic lamina propria via goblet cell-associated antigen passages (GAPs) and taken up by antigen presenting cells. GAP formation is inhibited by breastmilk-derived epidermal growth factor (EGF) which is highest in maternal milk at parturition and is diminished by weaning. We have previously shown that disruption of this process – via EGF receptor inhibition (EGFRi) day of life (DOL)4–8 or by conditional deletion of EGFR from goblet cells – results in premature antigen delivery. Consequently, this results in an early initial increase in FoxP3 expression in the colon that is unstable and, ultimately, lost by Tregs primed pre-weaning; this suggests that earlier education of T cells is incompatible with regulatory T cell differentiation in early life. EGFRi-treated FoxP3eGFP-Cre-ERT2ROSAlsl-YFPmice, whose FoxP3+ cells were YFP-labeled at DOL21, had a larger number of YFP+ T cells that lost FoxP3 expression than that of control mice, by DOL28. Further, compared to controls, wild-type mice treated with EGFRi DOL4–8 had increased IFNγ, TNFα, and IL-17a-expressing CD4 T cells when challenged with DSS colitis later in life. This suggests that early antigen delivery-associated FoxP3 instability may contribute to an increased propensity toward an inflammatory phenotype later in life.

Endogenous retroviruses act as a tonic signal for Treg induction and oral tolerance development

Abstract Endogenous retrovirus (ERVs) result from accumulated germline infections by ancient exogenous retroviruses and constitute a sizable proportion of the mammalian genome. Recent findings support the idea that these elements control tissue immune threshold of activation and inflammation. Within this context, our lab has recently described that, in the skin, the beneficial immunity to the microbiota depends on endogenous retrovirus expression. How the crosstalk between ERVs and the microbiota controls tissue immunity at other barrier sites and how dysregulation of this dialogue impairs tolerance responses remain unknown. Our results reveal that antiretroviral (anti-RT) treatment (blocking the conversion of ERV into cDNA) impairs gut regulatory T cell homeostasis and differentiation and compromises the induction of oral tolerance to food antigens. Consistently, our data demonstrate that antiretroviral treatment impairs type I IFN signaling in mucosal dendritic cells involved in the induction of regulatory T cells. Further, our results show that epithelial ERV expression is highly conserved across tissues and seems to be only partially affected by the microbiota in the small intestine. Altogether, our results propose that ERV control immunoregulation within the gastrointestinal tract by acting as a tonic signal required for Treg induction and differentiation thereby promoting oral tolerance and preventing allergic responses. This work was supported in part by intramural funds of NIAID, NIH. C.A.R is supported by Damon Runyon Fellowship program (DRG-2496-23).

The role of NFAT in CD8+Foxp3+ Tregs

Abstract CD8 +Foxp3 +regulatory T cells (CD8 Treg) correspond to a very low frequency population which can be observed during GVHD at early stage or in some cancer types. However, in vitro, around 30–60% of CD8 can express Foxp3 after induction culture with TCR stimulation and TGF-β (iCD8Treg). Why in healthy mice and humans this cell population has very low or non-frequency been still an unresolved question. In vitro, iCD8Tregs can suppress effector cells in a similar way as iCD4Treg. However, in vivo, in the IBD model, we observed that in contrast to iCD4Treg, iCD8Treg lose the Foxp3 expression and consequently their suppressive function. Also, iCD8Treg increase the IFN-γ production. These results suggest that iCD8Treg are not able to maintain the Foxp3 expression in comparison with iCD4Treg cells. What signaling pathway is responsible for the Foxp3 losing in iCD8Treg? We found a positive correlation between Foxp3 maintenance and cyclosporin A (CSA) concentration, and a reduction of IFN-γ in culture in iCD8Treg, but not for iCD4Treg. We evaluated the effect of CSA, an NFAT inhibitor, on the Tregs induction culture (with TGF-β) in the CD8 cells and found that there was no increase of Foxp3 expression. These results suggest that NFAT signaling plays a role in the Foxp3 maintenance but not in the induction of the iCD8Treg and this role is different from iCD4 Tregs.

Characterization of excretory/secretory products of the Taenia crassiceps cysticercus involved in the induction of regulatory T cells in vivo.

The ability to modulate the host immune response has allowed some parasites to establish themselves in the tissues of an immunocompetent organism. While some parasite excretion/secretion products (ESPs) were recently reported to induce differentiation of regulatory T cells (Tregs), their identity is not known. This work is aimed to identify and characterize ESPs of Taenia crassiceps cysticerci linked with Treg induction in vivo. ESPs were obtained from cultures of T. crassiceps cysticerci and inoculated in mice, measuring Treg levels by flow cytometry. Proteins in ESPs were analyzed by electrophoresis; then, ESPs were classified as either differential or conserved. Differentially included proteins were MS-sequenced and functionally characterized. Only 4 of 10 ESPs induced Tregs. Proteins with catalytic activity and those involved in immunological processes predominated, supporting the idea that these molecules could play an important role in the induction of Tregs.

Tumor-infiltrating mast cells stimulate ICOS+ regulatory T cells through an IL-33 and IL-2 axis to promote gastric cancer progression

IntroductionIn solid tumors, regulatory T cell (Treg) and mast cell perform different roles depending on the microenvironment. Nevertheless, mast cell and Treg-mediated interactions in gastric cancer (GC) are unclear, as are their regulation, function, and clinical significance. ObjectiveThe present study demonstrated the mechanism of tumor-infiltrating mast cells stimulating ICOS+ regulatory T cells via the IL-33/IL-2 axis to promote the growth of gastric cancer. MethodsAnalyses of 98 patients with GC were conducted to examine mast cell counts, ICOS+ Tregs, and the levels of IL-33 or IL-2. Isolated ICOS+ Treg and CD8+ T cell were stimulated, cultured and tested for their functional abilities in vitro and in vivo. ResultsGC patients exhibited a significantly more production of IL-33 in tumors. Mast cell stimulated by tumor-derived IL-33 exhibited a prolonged lifespan through IL-33 mediated inhibition of apoptosis. Moreover, mast cells stimulated by tumor-derived IL-33 secreted IL-2, which induced Treg expansion. These inducible Tregs displayed an activated immunosuppressive phenotype with positive expression for the inducible T cell co-stimulator (ICOS). In vitro, IL-2 from IL to 33-stimulated mast cells induced increased numbers of ICOS+ Tregs with increased immunosuppressive activity against proliferation and effector function of CD8+ T cell. In vivo, ICOS+ Tregs were treated with anti-IL-2 neutralizing antibody followed by co-injection with CD8+ T cells in GC mouse model, which showed an increased CD8+ T cell infiltration and effector molecules production, meanwhile tumor growth and progression were inhibited. Besides, reduction in GC patient survival was associated with tumor-derived ICOS+ Tregs. ConclusionOur results highlight a crosstalk between GC-infiltrating mast cells and ICOS+ Tregs and provide a novel mechanism describing ICOS+ Treg expansion and induction by an IL-33/mast cell/IL-2 signaling axis in GC, and also provide functional evidence that the modulation of this immunosuppressive pathway can attenuate GC-mediated immune tolerance.