Population Of Foxp3 Research Articles

Anti-allergic effects of Ulva-derived polysaccharides, oligosaccharides and residues in a murine model of food allergy

The medicinal benefits of green seaweed Ulva have been documented in traditional Chinese medicine literatures. Sulfated polysaccharides found in Ulva are recognized as the primary bioactive compounds, known for their immunomodulatory and anti-inflammatory properties. Despite this knowledge, the available information regarding anti-allergic activities of Ulva remains limited. The objective of this study was to prepare and characterize Ulva-derived polysaccharides (UP), oligosaccharides (UO), and residues (UR), followed by assessing their potential in improving allergic enteritis and gut microbiota in a murine model of ovalbumin (OVA)-induced food allergy. The immunomodulatory activities of UP, UO, and UR were evaluated by measuring the expression of serum antibodies, splenic cytokines and duodenal transcript factors of T cell subsets. The impact of UP, UO, and UR on enteric microbiota was explored by 16S rRNA gene sequencing analysis of fresh fecal samples from treated mice. Oral treatment of UP, UO, and UR noticeably attenuated allergic diarrhea and enteritis. Additionally, Ulva samples treatment decreased serum levels of IgG1 and OVA-specific IgE while increased the level of OVA-specific IgG. Enhanced production of IFN-γ and reduced production of IL-4 and IL-10 by splenocytes were observed in the treated mice. In parallel, Ulva samples treatment led to a decreased number of GATA3+ cells and an increased number of T-bet+ cells in the duodenum. However, the population of Foxp3+ cells was not significantly altered. Moreover, treatment of Ulva samples improved enteric dysbiosis evidenced by an increased abundance of Lactobacillus murinus, L. johnsonii, and L. reuteri, and a decreased abundance of Kineothrix alysoides, Lacrimispora saccharolytica, L. aerotolerans, and Erysipelotrichaceae in feces. In conclusion, UP, UO, and UR, which could modulate the Th1/Th2 immune balance, alleviate allergic enteritis and improve enteric dysbiosis in varying degrees, are potential to be developed into therapeutic agents for food allergy.

Abstract 4568: Evaluating response of renal cell carcinoma to tyrosine kinase inhibitor and immune checkpoint inhibitor using a human histo-culture platform

Abstract Tyrosine Kinase Inhibitors (TKIs) and Immune checkpoint inhibitors (ICIs) are used in first line treatment of clear cell renal cell carcinoma (ccRCC). Identifying patients who truly benefit from these treatments remains a challenge. Developing newer and better therapy options that fail in the clinical phase is yet another unmet need. Both these limitations could be addressed by employing testing platforms that best capture the heterogeneity and complexity of the tumor within the patient. FarcastTM TruTumor is a near native human histo-culture platform which retains the tumor and stroma along with the intra-tumoral immune compartment post culture that holds promise to improve treatment outcomes in patients. In this study, we developed a ccRCC platform using surgical excess specimens from consented patients and compared its immune profile with the head and neck squamous cell carcinoma (HNSCC) platform. ccRCC samples (n=10) were processed to generate explants and cultured for 72h and interrogated for response to treatment with Sunitinib (TKI:27.7ng/ml) or Nivolumab (anti-PD1:132µg/ml). On comparison of immune profiles between HNSCC and ccRCC at baseline, we observed a significantly lower total immune content in ccRCC. ccRCC showed comparatively higher variation in myeloid (70%CV) and lymphoid compartments (30%CV) as compared to HNSCC. Live tumor and immune cell population was found to be well preserved post-culture in ccRCC. Presence of various T cell sub-populations, monocyte and macrophage population post culture were confirmed using flowcytometry. Sunitinib treatment significantly increased caspase-3 expression (8/10 samples, p value<0.01), along with decrease in tumor content in 4/10 samples (average drop 23%). Two samples which did not respond to Sunitinib treatment showed an increase in Interferon gamma (IFNg) (Log2FC ± SD, 2.7± 0.7) and Granzyme B (Log2FC ± SD, 1.05± 0.85) secretion, in response to Nivolumab treatment. Of these, in one sample we observed an increase in CD8+ Granzyme B, CD8+ Ki67 and decrease in CD4+ FoxP3 population, with concomitant decrease in Pan CK+ population by flowcytometry. In this sample, we observed a decrease in tumor content indicating anti-tumor response to Nivolumab treatment. In summary, the TruTumor platform potentially offers personalized treatment choices to patients improving their chances of recovery. In addition, this platform could provide powerful insights into the mechanisms of a wide range of therapy molecules in development to predict their efficacy better than other simplistic and non-human testing models. Citation Format: Satish Sankaran, Kowshik Jaganathan, Gowri Shankar K, Saurabh Bhargav, Ganesh MS, Amritha Prabha, Prakash BV, Syamkumar V, Biswajit Das, Vasanth K, Manimaran A, Chandan Bhowal, Rajashekar M, Oliyarasi M, Ritu Malhotra, Govindraj K, Nandini Pal Basak. Evaluating response of renal cell carcinoma to tyrosine kinase inhibitor and immune checkpoint inhibitor using a human histo-culture platform. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4568.

Donor bone-marrow CXCR4+ Foxp3+ T-regulatory cells are essential for costimulation blockade-induced long-term survival of murine limb transplants

Vascularized composite allotransplantation (VCA) allows tissue replacement after devastating loss but is currently limited in application and may be more widely performed if maintenance immunosuppression was not essential for graft acceptance. We tested whether peri-transplant costimulation blockade could prolong VCA survival and required donor bone-marrow cells, given that bone-marrow might promote graft immunogenicity or graft-versus-host disease. Peritransplant CD154 mAb/rapamycin (RPM) induced long-term orthotopic hindlimb VCA survival (BALB/c->C57BL/6), as did CTLA4Ig/RPM. Surprisingly, success of either protocol required a bone-marrow-associated, radiation-sensitive cell population, since long-bone removal or pre-transplant donor irradiation prevented long-term engraftment. Rejection also occurred if Rag1−/− donors were used, or if donors were treated with a CXCR4 inhibitor to mobilize donor BM cells pre-transplant. Donor bone-marrow contained a large population of Foxp3+ T-regulatory (Treg) cells, and donor Foxp3+ Treg depletion, by diphtheria toxin administration to DEREG donor mice whose Foxp3+ Treg cells expressed diphtheria toxin receptor, restored rejection with either protocol. Rejection also occurred if CXCR4 was deleted from donor Tregs pre-transplant. Hence, long-term VCA survival is possible across a full MHC disparity using peritransplant costimulation blockade-based approaches, but unexpectedly, the efficacy of costimulation blockade requires the presence of a radiation-sensitive, CXCR4+ Foxp3+ Treg population resident within donor BM.

Peripheral Autoimmune Regulator Induces Exhaustion of CD4+ and CD8+ Effector T Cells to Attenuate Autoimmune Diabetes in Non-Obese Diabetic Mice.

Autoimmune regulator (Aire) is one of the most crucial genes expressed in the thymus, where it orchestrates the promiscuous expression and presentation of tissue-specific antigens during thymocyte selection. The presence of Aire-expressing cells outside the thymus points toward its plausible extrathymic functions; however, the relative contribution of Aire-expressing cells of hematopoietic origin and their role in the modulation of autoimmune diseases are still obscure. Here, we report that non-obese diabetic mice with transgenic Aire expression under the control of the CD11c (integrin alpha X) promoter were significantly protected from autoimmune diabetes compared with their non-transgenic littermates. The protective effect of Aire transgene was mediated primarily by an increase in the “exhausted” populations of CD4+ and CD8+ T cells, both demonstrating poor expressions of interferon-γ and tumor necrosis factor-α. Both CD4+ and CD8+ effector T cells in transgenic mice displayed distinctive and differential expression of T-bet and Eomesodermin, respectively, in conjunction with high expression of programmed cell death protein-1 and other exhaustion-associated markers. Importantly, transgenic Aire expression did not result in any detectable changes in the population of Foxp3+ regulatory T (Treg) cells. Co-transfer experiments also demonstrated that Aire transgenic dendritic cells, as a “stand-alone” cell population, had the potential to suppress effector T cells in vivo without the support of Treg cells, but eventually failed to prevent the diabetogenesis in recipient mice. In conclusion, our study suggests that apart from its role in clonal deletion of autoreactive T cells or clonal diversion to Treg lineage, Aire can also contribute to tolerance by forcing effector T cells into a state of exhaustion with poor effector functions, thereby effectively containing autoimmune diseases.

Abstract 2647: TGF-β type I receptor inhibitor (TEW-7197) diminishes myeloma progression by multiple immunomodulatory mechanisms in combination with ixazomib

Abstract Background: Multiple myeloma (MM) is an incurable cancer of plasma cells. MM thrives in the bone marrow tumor microenvironment (TME) where several factors sustain MM growth and viability. TGF-β is a multi-functional cytokine elaborated by MM cells and by cells in the bone marrow (BM) TME. TGF-β stimulates MM progression through promotion of catabolic bone remodeling, IL-6 secretion and Th17 T cell development, which act in concert to induce osteolytic bone disease, immune suppression and myeloma progression. Therefore, we evaluated the anti-MM therapeutic potential of a small molecule inhibitor of the TGF-β type I receptor kinase (TβRI), TEW-7197, in combination with the proteasome inhibitor, ixazomib. Currently, TEW-7197 is being evaluated in phase I clinical trials in patients with solid tumors, and exposure to this agent is associated with an acceptable tolerability profile. Methods: The preclinical immunocompetent 5T33MM model (C57BL/KaLwRij) was used to characterize the role of TGF-β signaling in the BM TME. Mice bearing 5T33MM cells expressing luciferase were treated with TEW-7197, ixazomib and the combination of TEW-7197 plus ixazomib daily for 3 weeks, and evaluated for MM growth by bioluminescence imaging (BLI). Cellular and molecular assays were performed in human RPMI8226 and U266 as well as murine 5T33MM cells via apoptosis, real-time PCR and Western blotting. Immunological assays were performed via immunohistochemistry and FACS analyses. Peripheral blood monoclonal protein concentration, M-spike, was measured by ELISA. Results: TEW-7197 attenuated the growth and viability of human and murine MM cells by inducing apoptosis and it inhibited TGF-β-induced activation of Smad2/3 in MM cells in vitro. In our 5T33MM preclinical model, oral administeration of TEW-7197 as single agent inhibited MM progression as measured by peripheral blood monoclonal protein concentration and BLI before and after treatment. TEW-7197 also induced a decrease in mortality and an increase in body weight of mice bearing MM. TEW-7197 alone or combination with ixazomib also attenuated TGF-β activation of Smad2/3, reduced the expansion of CD11b+Gr-1+ myeloid derived suppressor cells (MDSCs) in BM TME, and diminished the population of Foxp3+ regulatory T cells (Treg) in the spleen. Combination therapy of TEW-7197 plus ixazomib prolonged survival and exhibited a synergistic anti-tumor effect when compared to either TEW-7197 or ixazomib alone by significant a reduction in both the M-spike and BLI. Conclusion: Our data demonstrate that the small molecule inhibitor of the TβRI, TEW-7197, effectively modulate the MM TME and is associated with a potent anti-myeloma effect in an immunocompetent murine model of MM. These data provide a rationale for clinical evaluation of the combination therapy of ixazomib and TEW-7197 as a potential therapeutic strategy to improve outcomes in patients with MM. Citation Format: Byung-Gyu Kim, Olga Sergeeva, George Luo, Sung Hee Choi, Zhenghong Lee, Seong-Jin Kim, John Letterio, Ehsan Malek. TGF-β type I receptor inhibitor (TEW-7197) diminishes myeloma progression by multiple immunomodulatory mechanisms in combination with ixazomib [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2647. doi:10.1158/1538-7445.AM2017-2647

Protective Role of ICOS and ICOS Ligand in Corneal Transplantation and in Maintenance of Immune Privilege

The interaction between the inducible costimulatory molecule (ICOS) and ICOS ligand (ICOSL) has been implicated in the differentiation and functions of T cells. The purpose of the present study was to determine the role of ICOS-ICOSL in the immune privilege of corneal allografts. Expression of ICOS and ICOSL mRNA from mouse eyes was assessed by RT-PCR. Corneas of C57BL/6 mice were orthotopically transplanted into the eyes of ICOS-/- BALB/c recipients and BALB/c wild-type (WT) recipients treated with anti-ICOSL mAb, and graft survival was assessed. A separate set of WT and ICOS-/- BALB/c mice received an anterior chamber injection of C57BL/6 splenocytes, and induction of allospecific anterior chamber-associated immune deviation (ACAID) was assessed. In vitro, cornea was incubated with T cells from WT and ICOS-/- BALB/c mice, and destruction of corneal endothelial cells (CECs) and the population of Foxp3+ CD25+ CD4+ T cells was assessed. Inducible costimulatory molecule ligand mRNA was constitutively expressed in the cornea, iris-ciliary body, and retina. Allograft survival in ICOS-/- recipients and WT recipients treated with anti-ICOSL mAb was significantly shorter than in control recipients. Anterior chamber-associated immune deviation was induced less efficiently in ICOS-/- mice. Destruction of CECs by alloreactive ICOS-/- T cells was enhanced compared with WT T cells. After coincubation with allogeneic corneal tissue, the proportion of regulatory T cells was significantly greater among WT T cells than in ICOS-/- T cells. The expression of ICOSL in the cornea and the ICOS-mediated induction of Foxp3+ CD4+ regulatory T cells may contribute to successful corneal allograft survival.

Abstract A063: Dissecting adipose tissue Treg differentiation and function in metabolism and obesity-associated cancer using TCR transgenic mice

Abstract Recent epidemiological and animal model studies indicate that overweight and obese individuals have increased risk not only of type-2 diabetes and cardiovascular diseases but also of various types of cancer. It was suggested that chronic, low-grade inflammation of the adipose tissue, and eventually systemically, is one of the major causes for obesity-associated metabolic abnormalities and cancer, but the trigger, progression and regulation of obesity-induced inflammation and how these processes might influence the development of cancer remain poorly understood. Our laboratory previously discovered a unique population of Foxp3+ CD4+ regulatory T cells (Tregs), with a distinct transcriptome and clonally expanded T cell receptor (TCR) repertoire, residing in the visceral adipose tissue (VAT) of mice and humans. These cells are critical for regulating local inflammation and maintaining systemic insulin sensitivity, but whether they regulate the development of obesity- associated cancers is currently unknown. Moreover, we are still at the early stages of an integrative understanding of the differentiation, trafficking, and expansion of this unique population of VAT cells. Attempting to fill some of these knowledge-gaps, we developed a VAT Treg TCR transgenic (Tg) mouse line, in which Tregs preferentially accumulate in VAT upon recognition of a currently unknown antigen. With this unique tool, we elucidated the life history of VAT Tregs, determined when and where they accumulate and acquired the unique phenotype, identified factors that are important for their homeostasis, and demonstrated their function in suppressing insulin resistance. We are currently in the process of elucidating their function in controlling the obesity- promoted liver inflammation and tumorigenesis. This study will provide foundations for Treg-based immunotherapy against the metabolic syndrome and obesity-associated cancer, while pointing to new cellular and molecular pathways that may constitute potential therapeutic targets. Citation Format: Chaoran Li, Christophe Benoist, Diane Mathis. Dissecting adipose tissue Treg differentiation and function in metabolism and obesity-associated cancer using TCR transgenic mice [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A063.

Abstract 350: The Pro-atherosclerotic Milieu Converts a Sub-population of Murine Peripheral T Regulatory Cells to a Non-suppressive Th1-like Foxp3+IFNγ+ Phenotype.

CD4+ T cell subsets play diverse roles in inflammation but may also display limited plasticity. The existence of a population of Foxp3+ T regulatory (Treg) cells that co-expresses Interferon-γ (IFNγ) has been demonstrated in several models of inflammation. In atherosclerosis, circulating Treg content inversely corresponds with atherogenesis, suggesting that inflammation might affect peripheral Treg (pTregs) maintenance. Thus, we sought to examine the fate of pTregs within atherosclerotic Apolipoprotein E-deficient (Apoe-/-) mice. Foxp3+IFNγ+ T cells were elevated within the aorta, spleen, and peripheral lymph nodes (PLNs) of atherosclerotic Apoe-/- versus C57BL/6 mice. Further phenotyping of Foxp3+IFNγ+ T cells revealed variable expression of Treg and Th1 markers, including low CTLA4, GITR, CD25 expression, equivalent PD1, CD73, FR4, expression and elevated Tbet, CD119, CXCR3, and CCR5 expression. To determine whether Foxp3+IFNγ+ T cells arise from de novo differentiation or peripheral conversion, we performed fate tracking experiments with co-adoptively transferred naïve T cells and pTregs, or lineage tracing Foxp3yfp-cre+ R26RtdTomato+ pTregs, to aged Apoe-/- mice. Naïve T cells failed to generate Foxp3+IFNγ+ T cells. In contrast, adoptively transferred Tregs maintained Foxp3 expression (50-60%) or adopted a Foxp3+IFNγ+ T phenotype (40-50%) within the spleen, peri-aortic lymph nodes, and aorta. To test the functionality of IFNγ+ Tregs, we isolated IFNγ+ pTregs, IFNγ- pTregs, and Foxp3GFP+ Tregs for T cell suppression assays. While IFNγ- pTregs and Foxp3GFP+ pTregs were equivalently suppressive, IFNγ+ pTregs failed to adequately suppress T cell proliferation. Together these results demonstrate that atherogenic inflammation affects the maintenance of pTregs, resulting in the generation of a subset of dysfunctional Foxp3+IFNγ+ T cells.

Recombinant IgG2a Fc (M045) multimers effectively suppress experimental autoimmune myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder caused by target-specific pathogenic antibodies directed toward postsynaptic neuromuscular junction (NMJ) proteins, most commonly the skeletal muscle nicotinic acetylcholine receptor (AChR). In MG, high-affinity anti-AChR Abs binding to the NMJ lead to loss of functional AChRs, culminating in neuromuscular transmission failure and myasthenic symptoms. Intravenous immune globulin (IVIg) has broad therapeutic application in the treatment of a range of autoimmune diseases, including MG, although its mechanism of action is not clear. Recently, the anti-inflammatory and anti-autoimmune activities of IVIg have been attributed to the IgG Fc domains. Soluble immune aggregates bearing intact Fc fragments have been shown to be effective treatment for a number of autoimmune disorders in mice, and fully recombinant multimeric Fc molecules have been shown to be effective in treating collagen-induced arthritis, murine immune thrombocytopenic purpura, and experimental inflammatory neuritis. In this study, a murine model of MG (EAMG) was used to study the effectiveness of this novel recombinant polyvalent IgG2a Fc (M045) in treating established myasthenia, with a direct comparison to treatment with IVIg. M045 treatment had profound effects on the clinical course of EAMG, accompanied by down-modulation of pathogenic antibody responses. These effects were associated with reduced B cell activation and T cell proliferative responses to AChR, an expansion in the population of FoxP3+ regulatory T cells, and enhanced production of suppressive cytokines, such as IL-10. Treatment was at least as effective as IVIg in suppressing EAMG, even at doses 25–30 fold lower. Multimeric Fc molecules offer the advantages of being recombinant, homogenous, available in unlimited quantity, free of risk from infection and effective at significantly reduced protein loads, and may represent a viable therapeutic alternative to polyclonal IVIg.

Abstract 385: Conversion of Established Murine Inducible T Regulatory Cells to Foxp3+IFN?+ T Cells in Atherosclerosis Occurs in an IL-12 Dependent Manner

In inflammation, T cell subsets are known to play diverse roles and recent evidence suggests that T helper cells display limited plasticity under specific stimuli. Evidence indicates that a decrease in the number of circulating Tregs corresponds with atherogenesis, and the existence of a population of Foxp3+ T regulatory cells that co-expresses inflammatory cytokines such as Interleukin-17A (IL-17A) and Interferon γ (IFNγ) has been demonstrated in models of inflammation. However, the cellular precursors and mechanisms underlying the generation of Foxp3+IL-17A+ and Foxp3+IFNγ+ T cells are unclear. Thus, we sought to study the fate of T regulatory cells during atherogenesis within 12 week western diet (WD)-fed Apolipoprotein E-deficient (Apoe-/-) mice. Apoe-/- mice have a population of Foxp3+IFNγ+ T regulatory cells within the aorta, spleen, peripheral lymph nodes (PLNs), peri-aortic LNs (PALNs), and mesenteric LNs (MLNs). To determine whether Foxp3+IFNγ+ Tregs arise from de novo differentiating naïve T cells or established Tregs, we performed a series of fate tracking experiments with co-adoptively transferred naïve T cells and inducible T regs in Apoe-/- mice. Both adoptively transferred T regs and naïve T cells were present in the blood and emigrated to the aorta, spleen, PLNs, MLNs, and PALNs of Apoe-/- mice. While naïve T cells were present in the tissues examined, they failed to appreciably differentiate to effector T cell fates. In contrast, half of the adoptively transferred Treg cells lost the expression of Foxp3 within all of the tissues examined. The remaining T regs maintained Foxp3 expression (40-45% of transferred Tregs) or adopted a Foxp3+IFNγ+ phenotype (5-10%). To assess how established T reg cells may convert to Foxp3+IFNγ+ T cells, in vitro differentiated iTregs were maintained in Treg conditions with or without IL-12 and assessed by flow cytometry. iTregs cultured without IL-12 did not become Foxp3+IFNγ+ cells. However in iTreg cultures supplemented with IL-12, 10% of Foxp3+ Tregs co-expressed IFNγ. Together, these results suggest that the pro-inflammatory conditions during atherogenesis affect the maintenance of established Treg cells, resulting in the loss of Foxp3 expression or the generation of Foxp3+IFNγ+ Tregs.

Changes of immunological parameters with administration of Japanese Kampo medicine (Juzen-Taihoto/TJ-48) in patients with advanced pancreatic cancer

The prognosis of pancreatic cancer is extremely poor regardless of various combination therapies. Immunoaugumentation against tumor cells was recently A focus. We reported that the population of Foxp3(+)CD25(+)CD4(+) regulatory T cells (Foxp3(+)Treg) was the new parameter for the estimation of host immunity and had correlation with tumor aggressiveness. Here we show the immunoaugumentation effects of Japanese Kampo medicine, Juzen-Taihoto/TJ-48, empirically considered as an immunoaugumentation drug, with investigation of Treg and other immunological parameters. Peripheral Foxp3(+) Treg populations, CD4/CD8 ratio, and CD57(+) cells (NK cells) populations in advanced pancreatic cancer patients (n = 30, stage VI A and B according to TNM classification) were estimated after TJ-48 administration for 14 days before the anti-cancer therapy. Treg populations were significantly increased compared to healthy donors (Mann-Whitney U test, P < 0.001). Administration of Juzen-Taihoto/TJ-48 significantly decreased Treg populations (Mann-Whitney U test, P < 0.001) and increased the CD4/CD8 ratio (Mann-Whitney U test, P < 0.01), even though CD57(+) cell populations did not change significantly. Juzen-Taihoto/TJ-48 increased regulatory activities in T cells through decreasing Foxp3(+) Treg populations in advanced pancreatic cancer patients. This effect can lead to immunoaugumentation for various combination therapies.

Analysis of Suppressor and Non-Suppressor FOXP3+ T Cells in HIV-1-Infected Patients

Recently, it was shown that peripheral blood FOXP3+CD4+ T cells are composed of three phenotypic and functionally distinct subpopulations. Two of them having in vitro suppressive effects were characterized as resting Treg cells (rTregs) and activated Treg cells (aTregs). A third subset, identified as FOXP3+ non-Tregs, does not display any suppressor activity and produce high levels of Th1 and Th17 cytokines upon stimulation. In the present study we focus on the characteristics of these three subsets of FOXP3+CD4+ T cells in untreated HIV-1-infected patients. We found that the absolute counts of rTregs, aTregs and FOXP3+ non-Tregs were reduced in HIV-1 patients compared with healthy donors. The relative frequency of rTregs and aTregs was similar in HIV-1 patients and healthy donors, while the frequency of FOXP3+ non-Tregs was significantly higher in HIV-1 patients, reaching a maximum in those patients with the lower values of CD4 counts. Contrasting with the observations made in FOXP3- CD4+ T cells, we did not find a negative correlation between the number of rTregs, aTregs or FOXP3+ non-Tregs and virus load. Studies performed with either whole PBMCs or sorted aTregs and FOXP3+ non-Tregs cells showed that these two populations of FOXP3+ T cells were highly permissive to HIV-1 infection. Upon infection, FOXP3+ non-Tregs markedly down-regulates its capacity to produce Th1 and Th17 cytokines, however, they retain the ability to produce substantial amounts of Th2 cytokines. This suggests that FOXP3+ non-Tregs might contribute to the polarization of CD4+ T cells into a Th2 profile, predictive of a poor outcome of HIV-1-infected patients.

Identification and expansion of highly suppressive CD8+FoxP3+ regulatory T cells after experimental allogeneic bone marrow transplantation

AbstractFoxP3+ confers suppressive properties and is confined to regulatory T cells (Treg) that potently inhibit autoreactive immune responses. In the transplant setting, natural CD4+ Treg are critical in controlling alloreactivity and the establishment of tolerance. We now identify an important CD8+ population of FoxP3+ Treg that convert from CD8+ conventional donor T cells after allogeneic but not syngeneic bone marrow transplantation. These CD8+ Treg undergo conversion in the mesenteric lymph nodes under the influence of recipient dendritic cells and TGF-β. Importantly, this population is as important for protection from GVHD as the well-studied natural CD4+FoxP3+ population and is more potent in exerting class I–restricted and antigen-specific suppression in vitro and in vivo. Critically, CD8+FoxP3+ Treg are exquisitely sensitive to inhibition by cyclosporine but can be massively and specifically expanded in vivo to prevent GVHD by coadministering rapamycin and IL-2 antibody complexes. CD8+FoxP3+ Treg thus represent a new regulatory population with considerable potential to preferentially subvert MHC class I–restricted T-cell responses after bone marrow transplantation.

Expression of CD39 on FoxP3+ T regulatory cells correlates with progression of HBV infection

BackgroundAlthough it is known that regulatory T cells (Tregs) can suppress the function of effector T cells, and may contribute to impaired immune response, the precise role of Tregs during the course of hepatitis B virus (HBV) infection remains to be elucidated. A newly identified subset of the CD4+Foxp3+ Tregs, the CD39+ Tregs, has been associated with viral infections and autoimmune diseases. Therefore, we hypothesized that this discrete Treg subset may contribute to the chronic infection of HBV.ResultsInitial characterization studies of healthy peripheral CD39+FoxP3+CD4+ T cells revealed that the majority were CD45RA- Treg cells. Subsequent analysis of HBV-infected patients (38 asymptomatic HBV carriers (AsCs), 37 chronic active hepatitis B (CAH), 29 HBV-associated acute-on-chronic liver failure (ACLF)) and healthy individuals (25 controls) was conducted to assess association with HBV copy number and the liver injury marker alanine aminotransferase (ALT). A higher percentage of CD39+ Tregs was detected within the population of FoxP3+CD4+ T cells in peripheral blood of AsCs patients. Moreover, the percentage of CD39+ Tregs was significantly less in CAH and ACLF patients. The increased proportions of circulating CD39+ Tregs were positively correlated with serum viral load, but inversely correlated with serum ALT level.ConclusionThese findings not only suggest that CD39+ Treg cells may be involved in HBV disease progression but also identify CD39+ Tregs as a dynamic immune regulatory cell population that may represent a new target of immunomodulatory therapeutic interventions.

Regulatory T Cells Stay on Course

Regulatory T (Treg) cells are thought to be susceptible to conversion into effector T cells. In this issue of Immunity, Miyao et al. (2012) provide evidence that the apparent plasticity of murine Foxp3(+) Treg cells is largely restricted to a defined subset of poorly committed Foxp3(+) cells.

CCL17 Promotes Intestinal Inflammation in Mice and Counteracts Regulatory T Cell–Mediated Protection From Colitis

Priming of T cells by dendritic cells (DCs) in the intestinal mucosa and associated lymphoid tissues helps maintain mucosal tolerance but also contributes to the development of chronic intestinal inflammation. Chemokines regulate the intestinal immune response and can contribute to pathogenesis of inflammatory bowel diseases. We investigated the role of the chemokine CCL17, which is expressed by conventional DCs in the intestine and is up-regulated during colitis. Colitis was induced by administration of dextran sodium sulfate (DSS) to mice or transfer of T cells to lymphopenic mice. Colitis activity was monitored by body weight assessment, histologic scoring, and cytokine profile analysis. The direct effects of CCL17 on DCs and the indirect effects on differentiation of T helper (Th) cells were determined in vitro and ex vivo. Mice that lacked CCL17 (Ccl17(E/E) mice) were protected from induction of severe colitis by DSS or T-cell transfer. Colonic mucosa and mesenteric lymph nodes from Ccl17-deficient mice produced lower levels of proinflammatory cytokines. The population of Foxp3(+) regulatory T cells (Tregs) was expanded in Ccl17(E/E) mice and required for long-term protection from colitis. CCR4 expression by transferred T cells was not required for induction of colitis, but CCR4 expression by the recipients was required. CCL17 promoted Toll-like receptor-induced secretion of interleukin-12 and interleukin-23 by DCs in an autocrine manner, promoted differentiation of Th1 and Th17 cells, and reduced induction of Foxp3(+) Treg cells. The chemokine CCL17 is required for induction of intestinal inflammation in mice. CCL17 has an autocrine effect on DCs that promotes production of inflammatory cytokines and activation of Th1 and Th17 cells and reduces expansion of Treg cells.

Trichinella spiralis antigens prime mixed Th1/Th2 response but do not induce de novo generation of Foxp3+ T cells in vitro.

SummaryMany parasitic helminth infections induce Th2-type immune responses and engage the regulatory network. In this study, we specifically investigated the influence of antigens derived from different life stages of the helminth Trichinella spiralis on the polarization of naive CD4+ T cells by dendritic cells. Results obtained from C57BL/6 mice showed that T. spiralis derived antigens have the capacity to induce bone marrow-derived dendritic cells to acquire an incompletely mature phenotype that promotes a significant proliferation of naive CD4+ T cells and a mixed Th1/Th2 cytokine profile with the predominance of Th2 cytokines. Increased production of IL-4, IL-9, IL-10 and IL-13 accompanied increased IFN-γ. Furthermore, dendritic cells pulsed with T. spiralis antigens did not induce an increase in the population of Foxp3+ T regulatory cells. Although other helminth antigens have demonstrated the capacity to induce de novo generation of Foxp3+ T regulatory cells, here our in vitro studies provide no evidence that T. spiralis antigens have this capacity.

GITR Ligand–Mediated Local Expansion of Regulatory T Cells and Immune Privilege of Corneal Allografts

The pathway between the glucocorticoid-induced tumor necrosis factor receptor family-related protein (GITR) and GITR ligand (GITRL) has been shown to control the function of regulatory T cells (Treg). The present study was conducted to investigate the role of this pathway and Treg in establishing immune privilege status for corneal allografts. Corneas of C57BL/6 mice were orthotopically transplanted into the eyes of BALB/c mice, and graft survival was assessed. A separate set of BALB/c mice received an anterior chamber injection of C57BL/6 splenocytes, and induction of allo-specific anterior chamber-associated immune deviation was assessed. Recipients were intraperitoneally administrated anti-GITRL, anti-CD25 monoclonal antibodies (mAb), or control immunoglobulin (IgG). Expressions of GITRL, GITR, and Foxp3 in the allografts were assessed. In vitro, cornea pretreated with anti-GITRL mAb or control IgG was incubated with T cells, and destruction of corneal endothelial cells and the population of Foxp3(+)CD25(+)CD4(+) T cells were assessed. GITRL was expressed constitutively in the cornea and iris-ciliary body. GITRL-expressing allografts were infiltrated with Foxp3+GITR+CD25+CD4(+) T cells. Blockade of GITRL did not affect allo-specific ACAID but led to infiltration of Foxp3(-)CD4(+) T cells and allograft rejection. Depletion of CD25+CD4(+) Treg also accelerated allograft rejection. Destruction of corneal endothelial cells by T cells was significantly enhanced in GITRL-blocked cornea compared with control cornea. Foxp3+CD25+CD4(+) T cells were increased after incubation with GITRL-expressing cornea, but not with GITRL-blocked cornea. Presence of Foxp3+CD25+CD4(+) Treg in the allograft is necessary for allograft survival. GITRL-dependent expansion of Treg within the cornea is one mechanism underlying immune privilege in corneal allografts.

FoxP3+ regulatory T cells are distinct from leukemia cells in HTLV‐1–associated adult T‐cell leukemia

Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma (ATLL). It has been postulated that ATLL cells might act as regulatory T cells (T(regs)) which, in common with ATLL cells, express both CD25 and FoxP3, and so contribute to the severe immune suppression typical of ATLL. We report here that the frequency of CD25(+) cells varied independently of the frequency of FoxP3(+) cells in both a cross-sectional study and in a longitudinal study of 2 patients with chronic ATLL. Furthermore, the capacity of ATLL cells to suppress proliferation of heterologous CD4(+)CD25(-) cells correlated with the frequency of CD4(+) FoxP3(+) cells but was independent of CD25 expression. Finally, the frequency of CD4(+)FoxP3(+) cells was inversely correlated with the lytic activity of HTLV-1-specific CTLs in patients with ATLL. We conclude that ATLL is not a tumor of FoxP3(+) regulatory T cells, and that a population of FoxP3(+) cells distinct from ATLL cells has regulatory functions and may impair the cell-mediated immune response to HTLV-1 in patients with ATLL.

Therapeutic efficacy of oxymatrine on chronic urticaria and its contribution to populations of Foxp3+ regulatory T cells in peripheral blood of patients.

Objective To explore the therapeutic effect of oxymatrine on chronic urticaria and its immune mechanism. Methods Totally, 69 patients were randomly and equally divided into 3 groups to receive treatment with oral mizolastine alone (mizolastine group), oral mizolastine and intramuscular oxymatrine (combination group), intramuscular oxymatrine alone (oxymatrine group), respectively. The dose of mizolastine and oxymatrine was 10 mg and 400 mg daily, respectively, and the treatment lasted 15 days. Efficacy was assessed according to pruritus intensity and number of erythema and wheals on day 7, 14, and 28 after the beginning of treatment. Venous blood was obtained from patients at the baseline, on day 14, 28 after the initiating of treatment and subjected to the detection of CD4+Foxp3+ regulatory T cell populations via three-color fluorescence flow cytometric analysis. Results The efficacy in combination and oxymatrine groups were significantly higher than that in mizolastine group (t = 49.18, P 0.05). The proportion of Foxp3+CD4+CD25+ regulatory T cells in peripheral blood was significantly increased in patients treated with oxymatrine, compared with normal human controls and patients treated with mizolastine (all P < 0.05). Conclusions Oxymatrine has a marked effect on the treatment of chronic urticaria, likely by increasing the proportion of Foxp3+CD4+CD25+ regulatory T cells in peripheral blood of patients. Key words: Urticaria; Sophora flavescens; Therapy; CD4-positive T-iymphocytes