Activation of CD25(+)CD4(+) regulatory T cells by oral antigen administration

Recent development of oral vaccines (Review)

Oral immunization can elicit an effective immune response and immune tolerance to specific antigens. When compared with the traditional injection route, delivering antigens via the gastrointestinal mucosa offers superior immune effects and compliance, as well as simplicity and convenience, making it a more optimal route for immunization. At present, various oral vaccine delivery systems exist. Certain modified bacteria, such as Salmonella, Escherichia coli and particularly Lactobacillus, are considered promising carriers for oral vaccines. These carriers can significantly enhance immunization efficiency by actively replicating in the intestinal tract following oral administration. The present review provided a discussion of the main mechanisms of oral immunity and the research progress made in the field of oral vaccines. Additionally, it introduced the advantages and disadvantages of the currently more commonly administered injectable COVID-19 vaccines, alongside the latest advancements in this area. Furthermore, recent developments in oral vaccines are summarized, and their potential benefits and side effects are discussed.

Obesity-induced hyperglycemia impairs oral tolerance induction and aggravates food allergy

Obesity and type 2 diabetes (T2D) have been found to be associated with abnormalities in several organs, including the intestine. These conditions can lead to changes in gut homeostasis, compromising tolerance to luminal antigens and increasing susceptibility to food allergies. The underlying mechanisms for this phenomenon are not yet fully understood. In this study, we investigated changes in the intestinal mucosa of diet-induced obese mice and found that they exhibited increased gut permeability and reduced Treg cells frequency. Upon oral treatment with ovalbumin (OVA), obese mice failed to develop oral tolerance. However, hyperglycemia treatment improved intestinal permeability and oral tolerance induction in mice. Furthermore, we observed that obese mice exhibited a more severe food allergy to OVA, and this allergy was alleviated after treatment with a hypoglycemic drug. Importantly, our findings were translated to obese humans. Individuals with T2D had higher serum IgE levels and downregulated genes related to gut homeostasis. Taken together, our results suggest that obesity-induced hyperglycemia can lead to a failure in oral tolerance and to exacerbation of food allergy. These findings shed light on the mechanisms underlying the relationship among obesity, T2D, and gut mucosal immunity, which could inform the development of new therapeutic approaches.

Role and Function of Regulatory T Cell in Chronic Rhinosinusitis with Nasal Polyposis

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a subtype of chronic rhinosinusitis characterized by high edema in the stroma, albumin deposition, and formation of pseudocysts. The pathogenesis of CRSwNP is not yet fully understood. Regulatory T (Treg) cells are a subset of CD4+ T cells that play a suppressive immunoregulatory role in the process of CRSwNP. Recent studies have found that there was a significant reduction in Treg cells in polyp tissues, which leads to the onset of CRSwNP. An imbalance between Th17 and Treg cells can also aggravate inflammation toward the Th2 type. This review focuses on our understanding of the function and role of Treg cells and their regulatory factors and clinical significance in CRSwNP. We also summarize the current drug treatments for CRSwNP with Tregs as the potential therapeutic target, which will provide new ideas for the treatment of CRSwNP in the future.

Modulating oxidative stress counteracts specific antigen-induced regulatory T-cell apoptosis in mice

Treg are known to have a central role in orchestrating immune responses, but less is known about the destiny of Treg after being activated by specific Ags. This study aimed to investigate the role of superoxide dismutase, an active molecule in the regulation of oxidative stress in the body, in the prevention of Treg apoptosis induced by specific Ags. Ag-specific Tregs were isolated from the DO11.10 mouse intestine. A food allergy mouse model was developed with ovalbumin as the specific Ag and here, we observed that exposure to specific Ag induced Treg apoptosis through converting the precursor of TGF-β to its mature form inside the Tregs. Oxidative stress was induced in Tregs upon exposure to specific Ags, in which Smad3 bound the latency-associated peptide to induce its degradation, converting the TGF-β precursor to its mature form, TGF-β. Suppressing oxidative stress in Tregs alleviated the specific Ag-induced Treg apoptosis in in vitro experiments and suppressed experimental food allergy by preventing the specific Ag-induced Treg apoptosis in the intestine. In conclusion, exposure to specific Ags induces Treg apoptosis and it can be prevented by upregulating superoxide dismutase or suppressing reactive oxidative species in Tregs.

Attenuation of GARP expression on regulatory T cells by protein transport inhibitors

An integrated understanding of the functional capacities of cells in the context of their physical parameters and molecular markers is increasingly demanded in immunologic studies. Regulatory T cells (Tregs) are a subpopulation of T cells involved in immune response modulation and mediating tolerance to self-antigen with their absence leading to a loss of tolerance. Glycoprotein repetitions A predominant (GARP) is a key marker for activated Tregs, but its detection may also be useful in determining the functional capacities of the cell. This study aims to deduce the optimal stimulation period and the impact of protein transport inhibitors (PTIs), commonly used in the detection of intracellular cytokines, on GARP detection. Through flow cytometric analysis we analyzed different cell culture conditions for optimal GARP expression on activated Tregs. Healthy donor PBMCs were stimulated with either Staphylococcal Enterotoxin B (SEB) or PMA/Ionomycin (PMA/Iono), in the presence and absence of PTIs monensin and/or brefeldin A (BFA) and GARP expression was assessed on CD4+ CD25+ FOXP3+ Tregs. The optimal stimulation period for the detection of GARP was highest at 24-h. Furthermore, we determined that GARP expression on Tregs is significantly reduced when cells are treated with the PTIs monensin and/or BFA following PMA/Iono stimulation. This effect was not seen following SEB stimulation. Therefore, due to the effects of PTIs, alternative methods should be considered when performing simultaneous analysis for cytokine expression and GARP expression on Tregs.

STAT6 Pathway Is Critical for the Induction and Function of Regulatory T Cells Induced by Mucosal B Cells

B cells could convert naïve T cells into regulatory T cells (so-called Treg-of-B cells) which have the ability to treat animal models of inflammatory diseases, including allergic asthma, collagen-induced arthritis and colitis; however, the mechanisms of Treg-of-B cell generation remain unclear. In this study, we investigated the role of STAT6 in the generation of Treg-of-B (P) cells, which Treg cells were generated by Peyer’s patch B cells (P stands for Peyer’s patch). CD4+CD25- T cells from wild type, STAT6 knockout and IL-4 knockout mice were cocultured with wild type Peyer’s patch B cells for Treg-of-B (P) cell generation. A murine asthmatic model was used to analyze the in vivo regulatory function of Treg-of-B (P) cells. The data demonstrated that STAT6 played a critical role in the generation of Treg-of-B (P) cells, which confirmed with STAT6-deficient T cells and the STAT6 inhibitor AS1517499. When STAT6 was lacking, Treg-of-B (P) cells exerted impaired suppressive ability with decreased LAG3 expression. Furthermore, Peyer’s patch B cells played an essential role in regulatory T cell generation. In the absence of Peyer’s patch B cells, T cells expressed decreased phosphorylated STAT6, which was followed by decreased LAG3 expression and impaired suppressive ability, suggesting that Peyer’s patch B cells provided the critical signal to activate STAT6 phosphorylation in T cells. Moreover, STAT6 deficient Treg-of-B (P) cells could not alleviate inflammation in an animal model of asthma in vivo. IL-4 was downstream of phosphorylated STAT6 and maintained Treg-of-B (P) cell survival with increased expression of Bcl-2 and Bcl_XL. We reported a novel finding that the STAT6-LAG3 signaling axis is important for the induction and function of Treg-of-B (P) cells.

Epigenetic mechanisms shape the underlining expression regulatory mechanisms of the STAT3 in multiple sclerosis disease

Objectives

Immunological tolerance is mediated by CD4⁺CD25⁺ regulatory T (Treg) cells. Studies have shown that thymic and peripheral generations of Treg cells depend on the CD28 signaling pathway. T helper 17 (Th17) cells are involved in the pathophysiology of various inflammatory diseases. Cytokines, such as interleukin (IL)-6 and TGF-β, regulate the reciprocal development of Th17 and Treg cells. In CD4⁺ T cells, signal transducer and activator of transcription 3 (STAT3) play a critical role in the induction of Th17 cell differentiation and inhibition of Treg cell development.

Results

In this study, we investigated the STAT3 methylation and gene expression status in patients with MS. Our study demonstrated that the level of STAT3 methylation decreased in relapsing–remitting MS patient compared to control groups, which the decreases were statistically significant. STAT3 gene expression increased in patient group relative to healthy one, and the increases were found to be statistically significant. According to our findings, it can be suggested that DNA hypermethylation of STAT3 affects the gene expression. In addition, there is a strong and significant negative correlation between the methylation status and mRNA level of STAT3.

Tolerogenic Immunomodulation by PEGylated Antigenic Peptides

Current treatments for autoimmune disorders rely on non-specific immunomodulatory and global immunosuppressive drugs, which show a variable degree of efficiency and are often accompanied by side effects. In contrast, strategies aiming at inducing antigen-specific tolerance promise an exclusive specificity of the immunomodulation. However, although successful in experimental models, peptide-based tolerogenic "inverse" vaccines have largely failed to show efficacy in clinical trials. Recent studies showed that repetitive T cell epitopes, coupling of peptides to autologous cells, or peptides coupled to nanoparticles can improve the tolerogenic efficacy of peptides, suggesting that size and biophysical properties of antigen constructs affect the induction of tolerance. As these materials bear hurdles with respect to preparation or regulatory aspects, we wondered whether conjugation of peptides to the well-established and clinically proven synthetic material polyethylene glycol (PEG) might also work. We here coupled the T cell epitope OVA323-339 to polyethylene glycols of different size and structure and tested the impact of these nano-sized constructs on regulatory (Treg) and effector T cells in the DO11.10 adoptive transfer mouse model. Systemic vaccination with PEGylated peptides resulted in highly increased frequencies of Foxp3+ Tregs and reduced frequencies of antigen-specific T cells producing pro-inflammatory TNF compared to vaccination with the native peptide. PEGylation was found to extend the bioavailability of the model peptide. Both tolerogenicity and bioavailability were dependent on PEG size and structure. In conclusion, PEGylation of antigenic peptides is an effective and feasible strategy to improve Treg-inducing, peptide-based vaccines with potential use for the treatment of autoimmune diseases, allergies, and transplant rejection.

Role of Regulatory T Cells in Regulating Fetal-Maternal Immune Tolerance in Healthy Pregnancies and Reproductive Diseases

Regulatory T cells (Tregs) are a specialized subset of T lymphocytes that function as suppressive immune cells and inhibit various elements of immune response in vitro and in vivo. While there are constraints on the number or function of Tregs which can be exploited to evoke an effective anti-tumor response, sufficient expansion of Tregs is essential for successful organ transplantation and for promoting tolerance of self and foreign antigens. The immune-suppressive property of Tregs equips this T lymphocyte subpopulation with a pivotal role in the establishment and maintenance of maternal tolerance to fetal alloantigens, which is necessary for successful pregnancy. Elevation in the level of pregnancy-related hormones including estrogen, progesterone and human chorionic gonadotropin promotes the recruitment and expansion of Tregs, directly implicating these cells in the regulation of fetal-maternal immune tolerance. Current studies have provided evidence that a defect in the number or function of Tregs contributes to the etiology of several reproductive diseases, such as recurrent spontaneous abortion, endometriosis, and pre-eclampsia. In this review, we provide insight into the underlying mechanism through which Tregs contribute to pregnancy-related immune tolerance and demonstrate the association between deficiencies in Tregs and the development of reproductive diseases.

Oral Administration of Flavonifractor plautii Strongly Suppresses Th2 Immune Responses in Mice

The bacterium Flavonifractor plautii (FP), which is found in human feces, has been reported to participate in catechin metabolism in the gut, but this bacterium's effects on immune function are unclear. We assessed the effect of oral administration of FP on the immune response in ovalbumin (OVA) -sensitized mice. We demonstrated that the FP treatment suppressed interleukin (IL)-4 in splenocytes and OVA-specific IgE production in serum from OVA-sensitized mice. Moreover, oral administration of FP augmented CD4⁺CD25⁺ T cells and CD103⁺CD11c⁺ DCs. In animals of the FP group, the proportion of FP was increased in the mesenteric lymph nodes (MLNs), as was the proportion of Deferribacteres in the cecum. Oral administration of FP may inhibit the Th2 immune response by incorporation into the MLNs and/or by inducing changes in the gut microbiota. Thus, FP may be useful in alleviating antigen-induced Th2 immune responses.

Treg Heterogeneity, Function, and Homeostasis

T-regulatory cells (Tregs) represent a unique subpopulation of helper T-cells by maintaining immune equilibrium using various mechanisms. The role of T-cell receptors (TCR) in providing homeostasis and activation of conventional T-cells is well-known; however, for Tregs, this area is understudied. In the last two decades, evidence has accumulated to confirm the importance of the TCR in Treg homeostasis and antigen-specific immune response regulation. In this review, we describe the current view of Treg subset heterogeneity, homeostasis and function in the context of TCR involvement. Recent studies of the TCR repertoire of Tregs, combined with single-cell gene expression analysis, revealed the importance of TCR specificity in shaping Treg phenotype diversity, their functions and homeostatic maintenance in various tissues. We propose that Tregs, like conventional T-helper cells, act to a great extent in an antigen-specific manner, which is provided by a specific distribution of Tregs in niches.

Exosomes Derived From T Regulatory Cells Suppress CD8+ Cytotoxic T Lymphocyte Proliferation and Prolong Liver Allograft Survival

BACKGROUND CD8+ cytotoxic T lymphocytes (CTLs) have been proved to exert crucial roles in immunological rejection. Exosomes (EXOs) secreted by CD4+CD25+ regulatory T (Treg) cells is believed to be deeply involved in immune regulation. Nevertheless, whether immunomodulatory effect of CD4+CD25+ Treg cells on CD8+ CTL depends on EXOs remains unknown and needs to be explored. MATERIAL AND METHODS We purified CD4+CD25+ Treg cells followed by in vitro amplification. EXOs in culture supernatants of Treg cells was separated and identified. The effect of CD4+CD25+ Treg cells and CD4+CD25+ Treg cells-derived EXOs on CD8+ CTL viability, proliferation, cell cycle mRNA, intracellular cytokines, and protein expression were investigated. RESULTS We successfully obtained EXOs from CD4+CD25+ Treg cells. The inhibition effect of EXOs on CD8+ CTL was concentration-dependent. In addition, the inhibition effect of CD4+CD25+ Treg cells could be reversed by GW4869, an EXOs inhibitor. The inhibition effect was associated with the regulation of IFN-γ and perforin. Our in vivo experiments proved that natural CD4+CD25+ Treg cells-released EXOs can prolong liver allograft survival. CONCLUSIONS CD4+CD25+ Treg cells-derived EXOs could become an alternative tool for manipulating the immune system to discover novel underlying immunomodulatory mechanisms.

Immunotherapy with oral administration of humanized anti-CD3 monoclonal antibody: a novel gut-immune system-based therapy for metaflammation and NASH

The immune system plays a role in the pathogenesis of non-alcoholic steatohepatitis (NASH) underlying hepatocyte injury and fibrosis progression at all disease stages. Oral administration of anti-CD3 monoclonal antibody (mAb) has been shown in preclinical studies to be an effective method for systemic immune modulation and alleviates immune-mediated disorders without T cell depletion. In the present review, we summarize the concept of the oral administration of humanized anti-CD3 mAb in patients with NASH and discuss the potential of this treatment to address the current requirements of treatments for NASH. Recently published preclinical and clinical data on oral administration of anti CD3 are discussed. Human trials have shown that the oral administration of anti-CD3 in healthy volunteers, patients with chronic hepatitis C virus (HCV) infection and patients with NASH and type 2 diabetes is safe and well tolerated, as well as biologically active. Oral anti-CD3 induces regulatory T cells, suppresses the chronic inflammatory state associated with NASH and exerts a beneficial effect on clinically relevant parameters. Foralumab is a fully human anti-CD3 mAb that has recently been shown to exert a potent anti-inflammatory effect in humanized mice. It is being developed for treatment of NASH and primary biliary cholangitis (PBC). Oral administration of anti CD3 may provide an effective therapy for patients with NASH.

CD55 Is Essential for CD103+ Dendritic Cell Tolerogenic Responses that Protect against Autoimmunity

Recent studies traced inflammatory bowel disease in some patients to deficiency of CD55 [decay-accelerating factor (DAF)], but the mechanism underlying the linkage remained unclear. Herein, we studied the importance of DAF in enabling processes that program tolerance in the gut and the eye, two immune-privileged sites where immunosuppressive responses are continuously elicited. Unlike oral feeding or ocular injection of ovalbumin in wild-type (WT) mice, which induced dominant immune tolerance, identical treatment of DAF^-/- mice or DAF^-/- to WT bone marrow chimeras did not. While 10% to 30% of mesenteric and submandibular lymph node CD4⁺ cells became robust T-regulatory cells (Tregs) in WT forkhead box P3 (Foxp3)-green fluorescent protein mice, few in either site became Tregs with little suppressor activity in DAF^-/- Foxp3-green fluorescent protein mice. Phenotyping of CD103⁺ dendritic cells (DCs) from the ovalbumin-fed DAF^-/- mice showed impaired expression of inducer of costimulation (ICOS) ligand, programmed death receptor 1-ligand 1 (PD1-L1), CxxxC chemokine receptor 1 (Cx3CR1), CCR7, and CCR9. Analyses of elicited DAF^-/- Foxp3⁺ Tregs showed reduced expression of interferon regulatory factor 8 (IRF-8)/aldehyde dehydrogenase 1 family member A2 (Aldh1a2) and glycoprotein A repetitions predominant/latency-associated protein associated with Treg transforming growth factor-β production and presentation, as well as integrin β6/integrin β8 associated with Treg and CD103⁺ DC transforming growth factor-β release. Thus, DAF is required for the properties of CD103⁺ DCs and their naïve CD4⁺ cell partners that together program tolerance.

Goblet cells: multifaceted players in immunity at mucosal surfaces

Goblet cells (GCs) are specialized epithelial cells that line multiple mucosal surfaces and have a well-appreciated role in barrier maintenance through the secretion of mucus. Moreover, GCs secrete anti-microbial proteins, chemokines, and cytokines demonstrating functions in innate immunity beyond barrier maintenance. Recently it was appreciated that GCs can form goblet cell-associated antigen passages (GAPs) and deliver luminal substances to underlying lamina propria (LP) antigen-presenting cells (APCs) in a manner capable of inducing adaptive immune responses. GCs at other mucosal surfaces share characteristics with the GAP forming intestinal GCs, suggesting that GAP formation may not be restricted to the gut, and that GCs may perform this gatekeeper function at other mucosal surfaces. Here we review observations of how GCs contribute to immunity at mucosal surfaces through barrier maintenance, the delivery of luminal substances to APCs, interactions with APCs, and secretion of factors modulating immune responses.

Emerging Functions of Regulatory T Cells in Tissue Homeostasis

CD4⁺Foxp3⁺ regulatory T-cells (Tregs) are a unique subset of helper T-cells, which regulate immune response and establish peripheral tolerance. Tregs not only maintain the tone and tenor of an immune response by dominant tolerance but, in recent years, have also been identified as key players in resolving tissue inflammation and as mediators of tissue healing. Apart from being diverse in their origin (thymic and peripheral) and location (lymphoid and tissue resident), Tregs are also phenotypically heterogeneous as per the orientation of ongoing immune response. In this review, we discuss the recent advances in the field of Treg biology in general, and non-lymphoid and tissue-resident Tregs in particular. We elaborate upon well-known visceral adipose tissue, colon, skin, and tumor-infiltrating Tregs and newly identified tissue Treg populations as in lungs, skeletal muscle, placenta, and other tissues. Our attempt is to differentiate Tregs based on distinctive properties of their location, origin, ligand specificity, chemotaxis, and specific suppressive mechanisms. Despite ever expanding roles in maintaining systemic homeostasis, Tregs are employed by large varieties of tumors to dampen antitumor immunity. Thus, a comprehensive understanding of Treg biology in the context of inflammation can be instrumental in effectively managing tissue transplantation, autoimmunity, and antitumor immune responses.

Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development

This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.

Regulatory T Cell-Mediated Tissue Repair

Regulatory T-cells (Treg cells) are a specific group of T-cells that maintain immune homeostasis by counteracting the immune responses of conventional T-cells. So far, the therapeutic applications of Treg cells have focused on the treatment of autoimmune diseases, as depletion of Treg cells or Treg-related genes is known to cause autoimmune defects. However, Treg cells can be a potential solution for tissue repair as they can terminate the pro-inflammatory phase and initiate the anti-inflammatory or regenerative phase at the tissue injury site. This review summarizes the known characteristics of Treg cells and lists examples of their therapeutic applications. The use of Treg cells in the treatment of myocardial infarctions, skeletal muscle injuries, and ischemia injuries has revealed their potential as a promising tissue repair method. We have also discussed the limitations and scope of Treg cells in tissue repair.

Antigen-specific regulatory T-cell responses to intestinal microbiota

The mammalian gastrointestinal tract can harbor both beneficial commensal bacteria important for host health, but also pathogenic bacteria capable of intestinal damage. It is therefore important that the host immune system mount the appropriate immune response to these divergent groups of bacteria-promoting tolerance in response to commensal bacteria and sterilizing immunity in response to pathogenic bacteria. Failure to induce tolerance to commensal bacteria may underlie immune-mediated diseases such as human inflammatory bowel disease. At homeostasis, regulatory T (Treg) cells are a key component of the tolerogenic response by adaptive immunity. This review examines the mechanisms by which intestinal bacteria influence colonic T-cells and B-cell immunoglobulin A (IgA) induction, with an emphasis on Treg cells and the role of antigen-specificity in these processes. In addition to discussing key primary literature, this review highlights current controversies and important future directions.

Oral treatment with foralumab, a fully human anti-CD3 monoclonal antibody, prevents skin xenograft rejection in humanized mice

Oral administration of biologics may be a feasible approach for immune therapy that improves drug safety and potentiates mechanisms of tolerance at mucosal barriers. We tested the ability of a fully human non-FcR binding anti-CD3 mAb, foralumab, to prevent skin xenograft rejection in mice with human immune systems. At an intragastric dose of 15μg, the drug could transit through the small bowel. Serum absorption and binding of lymphoid cells was seen and proliferative responses of splenic CD8+ T cells to mitogen were reduced. Five consecutive daily doses, then weekly dosing led to indefinite graft acceptance without depletion of peripheral T cells. Proliferative and cytokine responses to activation of splenocytes with PHA were reduced. The serum levels of IL-10 but not TNF were increased 6days after application of the skin graft. Oral treatment with anti-CD3 mAb may represent a feasible approach for immune modulation.

Respiratory Syncytial virus infection compromises asthma tolerance by recruiting interleukin-17A-producing cells via CCR6-CCL20 signaling

Asthma tolerance can be induced by breast-feeding or oral feeding with ovalbumin (OVA). Anergy or deletion of specific T cells and generation of T regulatory cells might contribute to this process. However, whether respiratory syncytial virus (RSV) infection would affect asthma tolerance is not very clear. Here, we first established asthma and oral tolerance mouse models and then analyzed airway hypersensitivity and asthma-related genes in the lung, CCR6-expressing IL-17A⁺ cells in the lungs, hilar or mesenteric lymph nodes (HLN or MLN) among control, asthmatic, tolerized, RSV infection, and RSV-infected asthmatic and tolerized groups. We also administrated CCL20 or IL-17A neutralizing antibody to RSV-infected tolerized mice to test whether RSV infection would mobilize CCR6-expressing IL-17A⁺ cells from MLN to the infected lungs. We found that tolerized mice infected with RSV developed asthma-like responses manifested by increasing airway hypersensitivity, exacerbating peribronchial inflammation, elevating lung asthma-related genes (Il17a, Mu5ac, and Gob5), accumulating CCR6-expressing IL-17A⁺ cells in the lungs and HLN with a reduction of this cell population in MLN. CCL20-CCR6 co-expression in RSV-infected tolerized MLN was reduced. Neutralization of CCL20 reduced CD3⁺CD4⁺CCR6⁺ cells in the RSV-infected tolerized HLN. Neutralization of IL-17A mitigated the compromising effects of RSV infection on asthma tolerance. Taken together, RSV infection impairs asthma tolerance by recruiting IL-17A-producing cells via CCR6-CCL20 signaling. The findings provide novel insight into exacerbation and therapeutic strategy of asthma under RSV infection.

T-cell expression of AhR inhibits the maintenance of pTreg cells in the gastrointestinal tract in acute GVHD

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that affects the function and development of immune cells. Here, we show that recipient mice receiving AhR^-/- T cells have improved survival and decreased acute graft-versus-host disease (aGVHD) in 2 different murine allogeneic bone marrow transplant (BMT) models. We also show that CD4⁺ T cells lacking AhR demonstrate reduced accumulation in secondary lymphoid tissue because of low levels of proliferation 4 days after BMT. Additionally, we found a significant increase in the quantity of peripherally induced regulatory donor T (pT_reg) cells in the colon of recipients transplanted with AhR^-/- T cells 14 days after transplant. Blockade of AhR using a clinically available AhR antagonist greatly enhanced the in vitro generation of inducible T_reg (iT_reg) cells from naïve CD4⁺ human T cells. We have identified AhR as a novel target on donor T cells that is critical to the pathogenesis of aGVHD.

Schistosoma japonicum HSP60-derived peptide SJMHE1 suppresses delayed-type hypersensitivity in a murine model

Background

Parasite-derived molecules with immunomodulatory properties, which have been optimised during host-parasite co-evolution, exhibit potential applications as novel immunotherapeutics. We have previously demonstrated that Schistosoma japonicum HSP60-derived peptide SJMHE1 induces CD4⁺CD25⁺ regulatory T-cells (Tregs) and that adoptively transferred SJMHE1-induced CD4⁺CD25⁺ Tregs inhibit delayed-type hypersensitivity (DTH) in mice. However, multiple concerns regarding this method render this treatment unsuitable. To gain further insights into the potential effects of SJMHE1, we used ovalbumin (OVA)-induced DTH and evaluated the effect of SJMHE1 on DTH mice.

Methods

BALB/c mice were sensitised with OVA alone or combined with SJMHE1 and then challenged with OVA to induce DTH. We first analysed the potential effects of SJMHE1 by measuring DTH responses, T-cell responses, cytokine secretion, and Treg proportions. We then evaluated the expression levels of IL-10 and TGF-β1 in CD4⁺CD25⁺ T-cells during DTH and Treg generation to identify the mechanism by which SJMHE1 suppresses DTH.

Results

SJMHE1 modulated the effector response against OVA-induced DTH and stimulated the production of the anti-inflammatory cytokines IL-10 and TGF-β1 in immunised mice through a mechanism involving CD4⁺CD25⁺ Tregs. SJMHE1-induced CD4⁺CD25⁺ Tregs expressed high levels of CTLA-4, IL-10, and TGF-β1, which substantially contributed to the suppressive activity during DTH. The administration of SJMHE1 to DTH in mice led to the expansion of CD4⁺CD25⁺ Tregs from CD4⁺CD25⁻ T-cells in the periphery, which inhibited DTH responses.

Conclusions

Our study proves that the parasite-driven peptide suppresses DTH in mice, which may confer a new option for inflammation treatment.

Immune responses to Mycobacterial heat shock protein 70 accompany self-reactivity to human BiP in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease, and a member of human heat shock protein (HSP) 70 protein family, Binding Immunoglobulin Protein (BiP), has been identified as an important autoantigen for T and B cells. We herein focused on Mycobacterial (Myc) HSPs and immune responses to MycHSPs in RA patients. Serum titers of antibodies against MycHSP70 were significantly elevated in RA patients and correlated with serum anti-BiP antibody titers. A MycHSP70-derived HLA-DR4 major epitope was identified using the proliferative capacity of RA PBMCs as an indicator. The major epitope, MycHSP70_287–306, was located at the corresponding position in the major epitope for human BiP_336–355, and a strong correlation was found between the proliferation of PBMCs in response to MycHSP70_287–306 and BiP_336–355. The immunization of HLA-DR4 transgenic mice with MycHSP70 induced the proliferation of T cells and development of anti-BiP antibodies. In contrast, the oral administration of MycHSP70_287–306 resulted in the amelioration of collagen-induced arthritis, serum antibody responses, and T cell proliferation. In conclusion, immune responses to MycHSP70 were associated with adaptive immunity against BiP in RA, and could be an important mechanism underlying the development of autoimmunity.

Mesenteric IL-10-producing CD5+ regulatory B cells suppress cow's milk casein-induced allergic responses in mice

Food allergy is a hypersensitive immune reaction to food proteins. We have previously demonstrated the presence of IL-10-producing CD5(+) B cells and suggested their potential role in regulating cow's milk casein allergy in humans and IgE-mediated anaphylaxis in mice. In this study, we determined whether IL-10-producing CD5(+) regulatory B cells control casein-induced food allergic responses in mice and, if so, the underlying mechanisms. The induction of oral tolerance (OT) by casein suppressed casein-induced allergic responses including the decrease of body temperature, symptom score, diarrhea, recruitment of mast cells and eosinophils into jejunum, and other biological parameters in mice. Notably, the population of IL-10-producing CD5(+) B cells was increased in mesenteric lymph node (MLN), but not in spleen or peritoneal cavity (PeC) in OT mice. The adoptive transfer of CD5(+) B cells from MLN, but not those from spleen and PeC, suppressed the casein-induced allergic responses in an allergen-specific and IL-10-dependent manner. The inhibitory effect of IL-10-producing CD5(+) B cells on casein-induced allergic response was dependent on Foxp3(+) regulatory T cells. Taken together, mesenteric IL-10-producing regulatory B cells control food allergy via Foxp3(+) regulatory T cells and could potentially act as a therapeutic regulator for food allergy.

Lymph node trafficking of regulatory T cells is prerequisite for immune suppression

Regulatory T cells have a crucial role in health and disease because of their immune regulation function. However, the anatomic sites where regulatory T cells exert optimal immune regulation are open to debate. In our current study with the use of a shear-stress flow assay, we found that regulatory T cells exhibited significantly decreased adhesion to either activated endothelial monolayer or intercellular adhesion molecule 1 or E-selectin-coated surfaces compared with activated effector T cells. The less transmigration capacity of the regulatory T cells prompted our speculation of preferential lymph node localization for the regulatory T cells that endowed these cells with immune regulation function in the most efficient manner. To test this hypothesis, the role of lymph node localization in regulatory T cell-mediated immune suppression was evaluated with a footpad inflammation model. We found that adoptively transferred regulatory T cells inhibited the development of footpad inflammation. In addition, although blockage of CCR7 or CD62L had no effect on the immune suppressive function of the regulatory T cells per se, pretreatment of the regulatory T cells with either CCR7 or CD62L blocking antibodies prevented their recruitment into draining lymph nodes and concomitantly abrogated the immune suppressive effects of adoptively transferred regulatory T cells during footpad inflammation. Our data demonstrate the crucial role of lymph node localization in regulatory T cell-mediated immune suppression and suggest a probable hierarchy in the anatomic sites for optimal immune regulation. Elucidating the relationships between the transmigration characteristics of the regulatory T cells and their immune regulation function will provide insightful information for regulatory T cell-based cell therapy.

Oral-tolerization Prevents Immune Responses and Improves Transgene Persistence Following Gene Transfer Mediated by Adeno-associated Viral Vector

Gene therapy represents a feasible strategy to treat inherited monogenic diseases and intramuscular (i.m.) injection of recombinant adeno-associated viral (AAV) vector is now recognized as a convenient and safe method of gene transfer. However, this approach is hampered by immune responses directed against the vector and against the transgenic protein. We used here to reproduce this situation a mouse model where robust immune responses are induced following injection of an AAV vector coding for an immunogenic transgenic protein. We show that prophylactic oral administration of the immunogenic protein before AAV-mediated gene transfer completely prevented antibody formation and cytotoxic CD8(+) T-cell response. Consistently, prophylactic oral-tolerization considerably improved long-term transgene persistence and expression. Mechanistically, inhibition of the cytotoxic immune response involved abortive proliferation of antigen-specific cytotoxic CD8(+) T cells, upregulation of the PD-1 immunoregulatory molecule, downregulation of the Bcl-2 antiapoptotic factor, and their deletion in the context of AAV-mediated gene transfer. Hence, gene therapy may represent an ideal situation where oral-tolerization can be adopted before or at the same time as vector injection to efficiently prevent deleterious immune responses directed against the transgenic protein.

Oral anti-CD3 immunotherapy for HCV-nonresponders is safe, promotes regulatory T cells and decreases viral load and liver enzyme levels: results of a phase-2a placebo-controlled trial

Orally administered anti-CD3 antibodies are biologically active in the gut through induction of regulatory T cells, exert an immune-modulatory effect, and alleviate insulin resistance and liver damage in patients with NASH.

AIMS

To determine the safety of oral anti-CD3 monoclonal antibody (MAb) immunotherapy in chronic HCV patients with associated immune dysfunction.

METHODS

Four groups (n = 9) of chronic HCV patients who were nonresponders to interferon plus ribavirin therapy received oral placebo (group A) or anti-CD3 MAb at one of three dosage levels for 30 days. Patients were followed for safety parameters and serum levels of liver enzymes, virus, cytokines and regulatory T cells.

RESULTS

Oral anti-CD3 immunotherapy was safe and well tolerated; no treatment-related adverse events were noted. The following improvements were noted relative to pretreatment levels: HCV viral load and AST and ALT levels decreased in the low- and high-dose groups following 30 days of therapy. In two of the treated groups, an increase in regulatory T cells (CD4(+) CD25(+) ) was noted. The positive effects were somewhat more apparent in subjects with initially elevated liver enzyme levels.

CONCLUSIONS

Oral anti-CD3 MAb immunotherapy for nonresponder HCV patients was safe and well tolerated. Trends and statistically significant improvements were observed as reductions in viral load and liver enzyme levels, along with an increase in regulatory T-cell levels. These data support a role for the immune system in the pathogenesis of HCV infection and suggest that this immunotherapy is worthy of evaluation in combination with HCV antiviral drugs.

Mycobacterial heat shock protein 65 (mbHSP65)-induced atherosclerosis: Preventive oral tolerization and definition of atheroprotective and atherogenic mbHSP65 peptides

OBJECTIVE

The aim of this study was to identify atherogenic and atheroprotective peptides of bacterial HSP60 [taking mycobacterial HSP65 (mbHSP65) as a potent paradigmatic representative] that could be used as candidates for an orally applied tolerizing vaccine against atherosclerosis.

METHODS

ApoE(-/-) mice were immunized with mbHSP65 protein or peptides, given mbHSP65 orally and then kept either on chow or high cholesterol diet. Atherosclerosis was assessed by en face and immunohistological analysis. Anti-HSP autoantibodies were detected by ELISA. The number and in vitro suppressive function of splenic and lymph node regulatory T cells (Tregs) were analyzed by flow cytometry. Specific T cell reactivity against mbHSP65 protein or peptides was assessed by proliferation assay.

RESULTS

Decreased lesion size was accompanied by (a) increased splenic Treg numbers; (b) increased interleukin (IL)-10 mRNA levels in the aorta; (c) increased levels of anti-mbHSP65 and anti-mouse HSP60 antibodies pointing to pro-eukaryotic HSP60 humoral crossreaction, not curtailed by oral tolerization; (d) most importantly, we identified and functionally characterized novel atherogenic and atheroprotective mbHSP65 epitopes.

CONCLUSION

Atheroprotective mbHSP65 peptides may be considered as potential candidates for the development of a tolerizing vaccine to prevent and treat atherosclerosis, while keeping protective immunity to non-atherogenic domains of mbHSP65 intact.

Characterization and functional studies of forkhead box protein 3(-) lymphocyte activation gene 3(+) CD4(+) regulatory T cells induced by mucosal B cells

The induction of mucosal tolerance has been demonstrated to be an effective therapeutic approach for the treatment of allergic diseases. Our previous study demonstrated that Peyer's patch B cells could convert naive T cells into regulatory T cells (so-called Treg -of-B(P) cells); however, it is important to characterize this particular subset of Treg -of-B cells for future applications. This study aimed to investigate the role of lymphocyte activating gene 3 (LAG3) in mediating the regulatory function of Treg -of-B(P) cells induced by mucosal follicular B (FOB) cells. Microarray analysis and real-time polymerase chain reaction (PCR) were used to assess the gene expression pattern of Treg -of-B(P) cells. To evaluate the role of LAG3, the in-vitro suppressive function and the alleviation of airway inflammation in a murine model of asthma was assessed. Our data indicated that FOB cells isolated from Peyer's patches had the ability to generate more suppressive Treg -of-B cells with LAG3 expression, compared with CD23(lo) CD21(lo) B cells. LAG3 is not only a marker for Treg -of-B(P) cells, but also participate in the suppressive ability. Moreover, CCR4 and CCR6 could be detected on the LAG3(+) , not LAG3(-) , Treg -of-B(P) cells and would help cells homing to allergic lung. In the murine model of asthma, the adoptive transfer of LAG3(+) Treg -of-B(P) cells was able to sufficiently suppress T helper type 2 (Th2) cytokine production, eosinophil infiltration and alleviate asthmatic symptoms. LAG3 was expressed in Treg -of-B(P) cells and was also involved in the function of Treg -of-B(P) cells. In the future, this particular subset of Treg -of-B cells might be used to alleviate allergic symptoms.

Oral mixture of autologous colon-extracted proteins for the Crohn’s disease: A double-blind trial

AIM: To evaluate the safety and efficacy of oral administration of Alequel™, an autologous protein-containing colon extract.

METHODS: A total of 43 patients were enrolled in a randomized, placebo-controlled, double-blind trial. Patients were orally administered with autologous protein-containing colon extract three doses of autologous study drug per week for 15 wk, for a total of 45 doses. Patients were followed for safety parameters. Remission was defined as a Crohn’s disease activity index (CDAI) score of less than or equal to 150. All patients were followed for changes in subsets of T cells by fluorescence-activated cell sorting analysis.

RESULTS: Analysis was performed on a total number of evaluable patients of 14 in the study drug group and 15 in the placebo group. Treatment was well tolerated by all patients. No major treatment-related adverse events were reported or observed in any of the treated patients during the feeding or follow-up periods. Between weeks 6 and 9 of the study, six of the 14 (43%) evaluable subjects who received the study drug achieved a CDAI of 150 or lower. In contrast, five of the 15 (33%) evaluable subjects in the placebo group achieved remission. Between weeks 9 and 12, the remission rates were 50% and 33% for the drug group and placebo group, respectively. Among the drug-treated subjects who achieved remission, the effect of the drug was judged as stable in eight of the 14 subjects as measured by at least two CDAI scores indicating remission in the 15-wk treatment period. A decreased percentage of peripheral natural killer T regulatory cells (a decrease of 28% vs an increase of 16%) and an increased ratio of CD4⁺/CD8⁺ T lymphocytes (an increase of 11% vs a decrease of 9%) were noted in subjects with a significant clinical response.

CONCLUSION: Oral administration of the autologous colonic extract could be a safe and effective for the treatment of patients with moderate to severe Crohn’s disease.

Induced miR-99a expression represses Mtor cooperatively with miR-150 to promote regulatory T-cell differentiation

Peripheral induction of regulatory T (Treg) cells provides essential protection from inappropriate immune responses. CD4(+) T cells that lack endogenous miRNAs are impaired to differentiate into Treg cells, but the relevant miRNAs are unknown. We performed an overexpression screen with T-cell-expressed miRNAs in naive mouse CD4(+) T cells undergoing Treg differentiation. Among 130 candidates, the screen identified 29 miRNAs with a negative and 10 miRNAs with a positive effect. Testing reciprocal Th17 differentiation revealed specific functions for miR-100, miR-99a and miR-10b, since all of these promoted the Treg and inhibited the Th17 program without impacting on viability, proliferation and activation. miR-99a cooperated with miR-150 to repress the expression of the Th17-promoting factor mTOR. The comparably low expression of miR-99a was strongly increased by the Treg cell inducer "retinoic acid", and the abundantly expressed miR-150 could only repress Mtor in the presence of miR-99a. Our data suggest that induction of Treg cell differentiation is regulated by a miRNA network, which involves cooperation of constitutively expressed as well as inducible miRNAs.

Heme oxygenase-1 confers protection and alters T-cell populations in a mouse model of neonatal intestinal inflammation

BACKGROUND

Necrotizing enterocolitis (NEC), an intestinal inflammatory disease affecting premature infants, is associated with low regulatory T (Treg) to effector T (Teff) cell ratios. We recently demonstrated that heme oxygenase-1 (HO-1) deficiency leads to increased NEC development. Here, we investigated the effects of HO-1 on T-cell proportions in a murine NEC-like injury model.

METHODS

Intestinal injury was induced in 7-d-old wild-type (WT) or HO-1 heterozygous (HO-1 Het) pups by formula-feeding every 4 h for 24-78 h by oral gavage and exposures to 5%O2. Controls remained breastfed. HO-1 was induced in WT pups by administering heme preinjury induction. Lamina propria T cells were identified by flow cytometry. For adoptive transfer studies, WT splenic/thymic Tregs were injected intraperitoneally into HO-1 Het pups 12-24 h preinduction.

RESULTS

Het mice showed increased intestinal injury and decreased Treg/Teff ratios. Genes for pattern recognition (Toll-like receptor-4, C-reactive protein, MyD88) and neutrophil recruitment increased in Het pups after NEC induction. Inducing intestinal HO-1 decreased NEC scores and incidence, and increased Treg/Teff ratios. Moreover, adoptive transfer of Tregs from WT to HO-1 Het pups decreased NEC scores and incidence and restored Treg/Teff ratios.

CONCLUSION

HO-1 can change Treg proportions in the lamina propria of young mice under inflammatory conditions, which might, in part, confer intestinal protection.

Oral Administration of OKT3 MAb to Patients with NASH, Promotes Regulatory T-cell Induction, and Alleviates Insulin Resistance: Results of a Phase IIa Blinded Placebo-Controlled Trial

Oral administration of anti-CD3 antibodies induced regulatory T cells (Tregs) alleviating the insulin resistance and liver damage in animal models.

OBJECTIVE

To determine the safety and biological effects of oral OKT3 monoclonal antibody (Balashov et al. Neurology 55:192-8, 2000) in patients with NASH.

DESIGN

In this Phase-IIa trial, four groups of patients with biopsy-proven NASH (n = 9/group) received placebo (group A) or oral OKT3 (group B: 0.2; C: 1.0; D: 5.0 mg/day) for 30 days. Patients were followed for safety, liver enzymes, glucose, lipid profile, oral glucose tolerance test (OGTT), serum cytokines and Tregs.

RESULTS

Oral OKT3 was well tolerated without treatment-related adverse events. OKT3 induced Tregs: with significant increases of CD4(+)LAP(+) (Latency associated peptide) and CD4(+)CD25(+)LAP(+) cells in Group D, and a significant increase in TGF-β in Groups C and D. AST decreased significantly in group D and a trend in Groups B and C. Fasting plasma glucose decreased significantly in all treatment groups compared with placebo. OGTT decreased significantly in Group D. Correlations were observed between the changes in several immune-modulatory effects and clinical biomarkers. While serum anti-CD3 levels where undetectable increases in human anti-mouse antibody levels were observed in Groups C and D.

CONCLUSION

Oral administration of anti-CD3 MAb to patients with NASH was safe and well tolerated. Positive biological effects were noted in several hepatic, metabolic and immunologic parameters. These findings provide the basis for future trials to investigate the effect of oral anti-CD3 MAb immunotherapy in patients with NASH.

Exchange protein directly activated by cAMP modulates regulatory T-cell-mediated immunosuppression

The cAMP signalling pathway plays an essential role in immune functions. In the present study we examined the role of the cAMP/EPAC1 (exchange protein directly activated by cAMP) axis in regulatory T-cell (Treg)-mediated immunosuppression using genetic and pharmacological approaches. Genetic deletion of EPAC1 in Tregs and effector T-cells (Teffs) synergistically attenuated Treg-mediated suppression of Teffs. Mechanistically, EPAC1 inhibition enhanced activation of the transcription factor STAT3 (signal transducer and activator of transcription 3) and up-regulated SMAD7 expression while down-regulating expression of SMAD4. Consequently, CD4+ T-cells were desensitized to transforming growth factor (TGF) β1, a cytokine employed by Tregs to exert a broad inhibitory function within the immune system. Furthermore, deletion of EPAC1 led to production of significant levels of ovalbumin IgG antibodies in a low-dose, oral-tolerance mouse model. These in vivo observations are consistent with the finding that EPAC1 plays an important role in Treg-mediated suppression. More importantly, pharmacological inhibition of EPAC1 using an EPAC-specific inhibitor recapitulates the EPAC1 deletion phenotype both in vivo and in vitro. The results of the present study show that EPAC1 boosts Treg-mediated suppression, and identifies EPAC1 as a target with broad therapeutic potential because Tregs are involved in numerous pathologies, including autoimmunity, infections and a wide range of cancers.

In vivo anti-LAP mAb enhances IL-17/IFN-γ responses and abrogates anti-CD3-induced oral tolerance

Regulatory T cells (Tregs) play a critical role in the maintenance of immunological tolerance. The best-characterized Tregs are those expressing the transcription factor Foxp3 and in vivo modulation of Foxp3 Tregs has been employed to study their role in immune homeostasis. Latency-associated peptide (LAP) is a membrane-bound TGF-β complex that has also been shown to play a role in Treg function and oral tolerance. We developed a novel anti-mouse LAP mAb that allowed us to investigate the effect of targeting LAP in vivo on immune function and on anti-CD3-induced oral tolerance. We found that in vivo anti-LAP mAb administration led to a decrease in the number of CD4+LAP+ Tregs in spleen and lymph nodes without affecting CD4+Foxp3+ Tregs. Spleen cells from anti-LAP-injected mice proliferated more in vitro and produced increased amounts of IL-2, IL-17 and IFN-γ. Moreover, injection of anti-LAP antibody abrogated the protective effect of oral anti-CD3 on experimental autoimmune encephalomyelitis (EAE). Finally, in vivo anti-LAP administration prior to myelin oligodendrocyte glycoprotein immunization resulted in severe EAE in the absence of pertussis toxin, which is used for EAE induction. Our findings demonstrate the importance of CD4+LAP+ T cells in the control of immune homeostasis and autoimmunity and provides a new tool for the in vivo investigation of murine LAP+ Tregs on immune function.

PD-1 regulates extrathymic regulatory T-cell differentiation

Treg cells and the programed death-1/programed death ligand-1 (PD-1/PD-L1) pathway are both critical for maintaining peripheral tolerance to self-Ags. A significant subset of Treg cells constitutively expresses PD-1, which prompted an investigation into the role of PD-1/PD-L1 interactions in Treg-cell development, function, and induction in vivo. The phenotype and abundance of Treg cells was not significantly altered in PD-1-deficient mice. The thymic development of polyclonal and monospecific Treg cells was not negatively impacted by PD-1 deficiency. The suppressive function of PD-1(-/-) Treg cells was similar to their PD-1(+/+) counterparts both in vitro and in vivo. However, in three different in vivo experimental settings, PD-1(-/-) conventional CD4(+) T cells demonstrated a strikingly diminished tendency toward differentiation into peripherally induced Treg (pTreg) cells. Our results demonstrate that PD-1 is dispensable for thymic Treg-cell development and suppressive function, but is critical for the extrathymic differentiation of pTreg cells in vivo. These data suggest that Ab blockade of the PD-1/PD-L1 pathway may augment T-cell responses by acting directly on conventional T cells, and also by suppressing the differentiation of pTreg cells.

Non-pulmonary allergic diseases and inflammatory bowel disease: A qualitative review

While the etiological underpinnings of inflammatory bowel disease (IBD) are highly complex, it has been noted that both clinical and pathophysiological similarities exist between IBD and both asthma and non-pulmonary allergic phenomena. In this review, several key points on common biomarkers, pathophysiology, clinical manifestations and nutritional and probiotic interventions for both IBD and non-pulmonary allergic diseases are discussed. Histamine and mast cell activity show common behaviors in both IBD and in certain allergic disorders. IgE also represents a key immunoglobulin involved in both IBD and in certain allergic pathologies, though these links require further study. Probiotics remain a critically important intervention for both IBD subtypes as well as multiple allergic phenomena. Linked clinical phenomena, especially sinonasal disease and IBD, are discussed. In addition, nutritional interventions remain an underutilized and promising therapy for modification of both allergic disorders and IBD. Recommending new mothers breastfeed their infants, and increasing the duration of breastfeeding may also help prevent both IBD and allergic diseases, but requires more investigation. While much remains to be discovered, it is clear that non-pulmonary allergic phenomena are connected to IBD in a myriad number of ways and that the discovery of common immunological pathways may usher in an era of vastly improved treatments for patients.

Plasmacytoid dendritic cells of the gut: relevance to immunity and pathology

Plasmacytoid dendritic cells (pDCs) are bone marrow-derived immune cells with the ability to express copious amounts of type I and III interferon (IFN) and can differentiate into antigen-presenting dendritic cells as a result of stimulation by pathogen-derived nucleic acid. These powerful combined functionalities allow pDCs to bridge the innate and adaptive immune systems resulting in a concerted pathogen response. The contribution of pDCs to gastrointestinal immunity is only now being elucidated and is proving to be a critical component in systemic immunity. This review will explore the immunology of pDCs and will discuss their involvement in human disease and tolerance with an emphasis on those in the gastrointestinal lymphoid tissue.

Molecular mechanisms of the adaptive, innate and regulatory immune responses in the intestinal mucosa of celiac disease patients

Celiac disease is a complex genetic disorder that affects the small intestine of genetically predisposed individuals when they ingest gluten, a dietary protein. Although several genome screens have been successful in identifying susceptibility loci in celiac disease, the only genetic contributors identified so far are the human leukocyte antigen (HLA)-DQ2/DQ8 molecules. One of the most important aspects in the pathogenesis of celiac disease is the activation of a T-helper 1 immune response, when the antigen-presenting cells that express HLA-DQ2/DQ8 molecules present the toxic gluten peptides to reactive CD4(+) T-cells. Recently, new insights into the activation of an innate immune response have also been described. It is generally accepted that the immune response triggers destruction of the mucosa in the small intestine of celiac disease patients. Hence, the activation of a detrimental immune response in the intestine of celiac disease patients appears to be key in the initiation and progression of the disease. This review summarizes the immunologic pathways that have been studied in celiac disease thus far, and will point to new potential candidate genes and pathways involved in the etiopathogenesis of celiac disease, which should lead to novel alternatives for diagnosis and treatment.

Is reactivation of toxoplasmic retinochoroiditis associated to increased annual rainfall?

BACKGROUND

Reactivation of toxoplasmic retinochoroiditis is the most frequent form of uveitis in Misiones, Argentina. Fluctuations in the number of patients consulting with this type of uveitis were detected during the last decade. Since the province was consecutively exposed to rainy and dry periods over the last years, we decided to explore whether a relationship between reactivation of toxoplasmic retinochoroiditis and rain might be established according to the data registered during the 2004-2010 period.

RESULTS

The frequency of toxoplasmic reactivation episodes increases when precipitation increases (mostly in second and fourth trimesters of each year). Analysis of the independent variables demonstrates that precipitation is a significant predictor of the frequency of reactivation episodes. Although registered toxoplasmic reactivations were more frequent during the third trimester of the year, the association between the third trimester and the reactivation episodes did not reach statistical significance.

CONCLUSION

Prolonged and intense rainfall periods were significantly associated with the reactivation of toxoplasmic retinochoroiditis. Changes promoted by this climatic condition on both the parasite survival in the soil as well as a putative effect on the host immune response due to other comorbidities are discussed.

Regulatory T Cells Control Immune Responses through Their Non-Redundant Tissue Specific Features

Regulatory T cells (Treg) are needed in the control of immune responses and to maintain immune homeostasis. Of this subtype of regulatory lymphocytes, the most potent are Foxp3 expressing CD4+ T cells, which can be roughly divided into two main groups; natural Treg cells (nTreg), developing in the thymus, and induced or adaptive Treg cells (iTreg), developing in the periphery from naïve, conventional T cells. Both nTreg cells and iTreg cells have their own, non-redundant roles in the immune system, with nTreg cells mainly maintaining tolerance toward self-structures, and iTreg developing in response to externally delivered antigens or commensal microbes. In addition, Treg cells acquire tissue specific features and are adapted to function in the tissue they reside. This review will focus on some specific features of Treg cells in different compartments of the body.

IgY antibodies anti-Tityus caripitensis venom: purification and neutralization efficacy

Tityus caripitensis is responsible for most of scorpion stings related to human incidents in Northeastern Venezuela. The only treatment for scorpion envenomation is immunotherapy based on administration of scorpion anti-venom produced in horses. Avian antibodies (IgY) isolated from chicken egg yolks represent a new alternative to be applied as anti-venom therapy. For this reason, we produced IgY antibodies against T. caripitensis scorpion venom and evaluated its neutralizing capacity. The anti-scorpion venom antibodies were purified by precipitation techniques with polyethylene glycol and evaluated by Multiple Antigen Blot Assay (MABA), an indirect ELISA, and Western blot assays. The lethality neutralization was evaluated by preincubating the venom together with the anti-venom prior to testing. The IgY immunoreactivity was demonstrated by a dose-dependent inhibition in Western blot assays where antibodies pre-absorbed with the venom did not recognize the venom proteins from T. caripitensis. The anti-venom was effective in neutralizing 2LD50 doses of T. caripitensis venom (97.8 mg of IgY neutralized 1 mg of T. caripitensis venom). Our results support the future use of avian anti-scorpion venom as an alternative to conventional equine anti-venom therapy in our country.

Adenoviral transduction of naive CD4 T cells to study Treg differentiation

Regulatory T cells (Tregs) are essential to provide immune tolerance to self as well as to certain foreign antigens. Tregs can be generated from naive CD4 T cells in vitro with TCR- and co-stimulation in the presence of TGFβ and IL-2. This bears enormous potential for future therapies, however, the molecules and signaling pathways that control differentiation are largely unknown. Primary T cells can be manipulated through ectopic gene expression, but common methods fail to target the most important naive state of the T cell prior to primary antigen recognition. Here, we provide a protocol to express ectopic genes in naive CD4 T cells in vitro before inducing Treg differentiation. It applies transduction with the replication-deficient adenovirus and explains its generation and production. The adenovirus can take up large inserts (up to 7 kb) and can be equipped with promoters to achieve high and transient overexpression in T cells. It effectively transduces naive mouse T cells if they express a transgenic Coxsackie adenovirus receptor (CAR). Importantly, after infection the T cells remain naive (CD44(low), CD62L(high)) and resting (CD25(-), CD69(-)) and can be activated and differentiated into Tregs similar to non-infected cells. Thus, this method enables manipulation of CD4 T cell differentiation from its very beginning. It ensures that ectopic gene expression is already in place when early signaling events of the initial TCR stimulation induces cellular changes that eventually lead into Treg differentiation.

CD4+CD25+ regulatory T cells-derived exosomes prolonged kidney allograft survival in a rat model

CD4(+)CD25(+) regulatory T cells (Tregs) are negative regulators of the immune system that induce and maintain immune tolerance. Exosomes are natural products released from many sources and play a role in antigen presentation, immunoregulation, and signal transduction. In order to determine whether exosomes can be released from Tregs and participate in transplantation tolerance, we isolated and purified Tregs-derived exosomes and established a rat model of kidney transplantation. We then transferred the autologous exosomes into recipients to observe the effect of transplantation tolerance in vivo and in vitro. From in vivo study, serum analysis and histology showed that the function of exosomes can postpone allograft rejection and prolong the survival time of transplanted kidney. From in vitro study, exosomes possessed the capacity to suppress T cells proliferation. Taken together, these results suggest that the Tregs-derived exosomes have a suppressive role on acute rejection and inhibit T cells proliferation, especially exosomes derived from donor-type Tregs, which imply that the Tregs-derived exosomes are one of far-end regulation mechanisms of Tregs. Thus, exosomes released from Tregs could be considered as a possible immunosuppressive reagent for the treatment of transplant rejection.

Mechanism of oral tolerance induction to therapeutic proteins

Oral tolerance is defined as the specific suppression of humoral and/or cellular immune responses to an antigen by administration of the same antigen through the oral route. Due to its absence of toxicity, easy administration, and antigen specificity, oral tolerance is a very attractive approach to prevent unwanted immune responses that cause a variety of diseases or that complicate treatment of a disease. Many researchers have induced oral tolerance to efficiently treat autoimmune and inflammatory diseases in different animal models. However, clinical trials yielded limited success. Thus, understanding the mechanisms of oral tolerance induction to therapeutic proteins is critical for paving the way for clinical development of oral tolerance protocols. This review will summarize progress on understanding the major underlying tolerance mechanisms and contributors, including antigen presenting cells, regulatory T cells, cytokines, and signaling pathways. Potential applications, examples for therapeutic proteins and disease targets, and recent developments in delivery methods are discussed.

Early life exposure to antibiotics and the risk of childhood allergic diseases: an update from the perspective of the hygiene hypothesis

The prevalence of allergic diseases has been growing rapidly in industrial countries during recent decades. It is postulated that growing up with less microbial exposure may render the immune system susceptible to a T helper type 2 (Th2)-predominant allergic response-also known as the hygiene hypothesis. This review delineates recent epidemiological and experimental evidence for the hygiene hypothesis, and integrates this hypothesis into the association between early life exposure to antibiotics and the development of allergic diseases and asthma. Several retrospective or prospective epidemiological studies reveal that early exposure to antibiotics may be positively associated with the development of allergic diseases and asthma. However, the conclusion is inconsistent. Experimental studies show that antibiotics may induce the Th2-skewed response by suppressing the T helper type 1 (Th1) response through inhibition of Th1 cytokines and disruption of the natural course of infection, or by disturbing the microflora of the gastrointestinal (GI) tract and therefore jeopardizing the establishment of oral tolerance and regulatory T cell immune responses. The hygiene hypothesis may not be the only explanation for the rapid increase in the prevalence of allergic diseases and asthma. Further epidemiological and experimental studies addressing the issue of the impact of environmental factors on the development of allergic diseases and the underlying mechanisms may unveil novel strategies for the prevention and treatment of allergic diseases in the future.