FOXP3+ Tregs require WASP to restrain Th2-mediated food allergy.
ABSTRACT: In addition to the infectious consequences of immunodeficiency, patients with Wiskott-Aldrich syndrome (WAS) often suffer from poorly understood exaggerated immune responses that result in autoimmunity and elevated levels of serum IgE. Here, we have shown that WAS patients and mice deficient in WAS protein (WASP) frequently develop IgE-mediated reactions to common food allergens. WASP-deficient animals displayed an adjuvant-free IgE-sensitization to chow antigens that was most pronounced for wheat and soy and occurred under specific pathogen-free as well as germ-free housing conditions. Conditional deletion of Was in FOXP3+ Tregs resulted in more severe Th2-type intestinal inflammation than that observed in mice with global WASP deficiency, indicating that allergic responses to food allergens are dependent upon loss of WASP expression in this immune compartment. While WASP-deficient Tregs efficiently contained Th1- and Th17-type effector differentiation in vivo, they failed to restrain Th2 effector responses that drive allergic intestinal inflammation. Loss of WASP was phenotypically associated with increased GATA3 expression in effector memory FOXP3+ Tregs, but not in naive-like FOXP3+ Tregs, an effect that occurred independently of increased IL-4 signaling. Our results reveal a Treg-specific role for WASP that is required for prevention of Th2 effector cell differentiation and allergic sensitization to dietary antigens.
Project description:Impaired tolerance to innocuous particles during allergic asthma has been linked to increased plasticity of FoxP3+ regulatory T cells (Tregs) reprogramming into pathogenic effector cells, thus exacerbating airway disease. However, failure of tolerance mechanisms is driven by Th2 inflammatory signals. Therefore, the in vivo role of canonical IL-4 receptor ? (IL-4R?) signaling, an essential driver of Th2-type airway responses to allergens, on the regulatory function of FoxP3+ Tregs in allergic asthma was explored. Here, we used transgenic Foxp3cre IL-4R?-/lox and littermate control mice to investigate the role of IL-4 and IL-13 signaling via Tregs in house dust mite-induced (HDM-induced) allergic airway disease. We sensitized mice intratracheally on day 0, challenged them on days 6-10, and analyzed airway hyperresponsiveness (AHR), airway inflammation, mucus production, and cellular profile on day 14. In the absence of IL-4R? responsiveness on FoxP3+ Tregs, exacerbated AHR and airway inflammation were shown in HDM-sensitized mice. Interestingly, reduced induction of FoxP3+ Tregs accompanied increased IL-33 alarmin production and type 2 innate lymphoid cell activation in the lung, exacerbating airway hyperreactivity and lung eosinophilia. Taken together, our findings indicate that IL-4R?-unresponsive FoxP3+ Tregs result in exaggerated innate Th2-type, IL-33-dependent airway inflammation and a break in tolerance during allergic asthma.
Project description:Aeroallergens such as house dust mite (HDM), cockroach, and grass or tree pollen are innocuous substances that can induce allergic sensitization upon inhalation. The serine proteases present in these allergens are thought to activate the protease-activated receptor (PAR)-2, on the airway epithelium, thereby potentially inducing allergic sensitization at the expense of inhalation tolerance. We hypothesized that the proteolytic activity of allergens may play an important factor in the allergenicity to house dust mite and is essential to overcome airway tolerance. Here, we aimed to investigate the role of PAR-2 activation in allergic sensitization and HDM-induced allergic airway inflammation. In our study, Par-2 deficient mice were treated with two different HDM extracts containing high and low serine protease activities twice a week for a period of 5 weeks. We determined airway inflammation through quantification of percentages of mononuclear cells, eosinophils and neutrophils in the bronchial alveolar lavage fluid and measured total IgE and HDM-specific IgE and IgG1 levels in serum. Furthermore, Th2 and pro-inflammatory cytokines including IL-5, IL-13, Eotaxin-1, IL-17, KC, Chemokine (C-C motif) ligand 17 (CCL17) and thymic stromal lymphopoietin (TSLP), were measured in lung tissue homogenates. We observed that independent of the serine protease content, HDM was able to induce elevated levels of eosinophils and neutrophils in the airways of both wild-type (WT) and Par-2 deficient mice. Furthermore, we show that induction of pro-inflammatory cytokines by HDM exposure is independent of Par-2 activation. In contrast, serine protease activity of HDM does contribute to enhanced levels of total IgE, but not HDM-specific IgE. We conclude that, while Par-2 activation contributes to the development of IgE responses, it is largely dispensable for the HDM-induced induction of pro-inflammatory cytokines and airway inflammation in an experimental mouse model of HDM-driven allergic airway disease.
Project description:Only limited evidence is available regarding the cytokine repertoire of effector T cells associated with peanut allergy, and how these responses relate to IgE antibodies to peanut components.To interrogate T cell effector cytokine populations induced by Ara h 1 and Ara h 2 among peanut allergic (PA) children in the context of IgE and to evaluate their modulation during oral immunotherapy (OIT).Peanut-reactive effector T cells were analysed in conjunction with specific IgE profiles in PA children using intracellular staining and multiplex assay. Cytokine-expressing T cell subpopulations were visualized using SPICE.Ara h 2 dominated the antibody response to peanut as judged by prevalence and quantity among a cohort of children with IgE to peanut. High IgE (> 15 kU(A)/L) was almost exclusively associated with dual sensitization to Ara h 1 and Ara h 2 and was age independent. Among PA children, IL-4-biased responses to both major allergens were induced, regardless of whether IgE antibodies to Ara h 1 were present. Among subjects receiving OIT in whom high IgE was maintained, Th2 reactivity to peanut components persisted despite clinical desensitization and modulation of allergen-specific immune parameters including augmented specific IgG4 antibodies, Th1 skewing and enhanced IL-10. The complexity of cytokine-positive subpopulations within peanut-reactive IL-4(+) and IFN-?(+) T cells was similar to that observed in those who received no OIT, but was modified with extended therapy. Nonetheless, high Foxp3 expression was a distinguishing feature of peanut-reactive IL-4(+) T cells irrespective of OIT, and a correlate of their ability to secrete type 2 cytokines.Although total numbers of peanut-reactive IL-4(+) and IFN-?(+) T cells are modulated by OIT in highly allergic children, complex T cell populations with pathogenic potential persist in the presence of recognized immune markers of successful immunotherapy.
Project description:The transcriptional repressor Bcl6 is a critical arbiter of Th cell fate, promoting the follicular Th lineage while repressing other Th cell lineages. Bcl6-deficient (Bcl6(-/-)) mice develop a spontaneous and severe Th2-type inflammatory disease, thus warranting assessment of Bcl6 in regulatory T cell (Treg) function. Bcl6(-/-) Tregs were competent at suppressing T cell proliferation in vitro and Th1-type colitogenic T cell responses in vivo. In contrast, Bcl6(-/-) Tregs strongly exacerbated lung inflammation in a model of allergic airway disease and promoted higher Th2 responses, including systemic upregulation of microRNA-21. Further, Bcl6(-/-) Tregs were selectively impaired at controlling Th2 responses, but not Th1 and Th17 responses, in mixed chimeras of Bcl6(-/-) bone marrow with Foxp3(-/-) bone marrow. Bcl6(-/-) Tregs displayed increased levels of the Th2 transcription factor Gata3 and other Th2 and Treg genes. Bcl6 potently repressed Gata3 transcriptional transactivation, providing a mechanism for the increased expression of Th2 genes by Bcl6(-/-) Tregs. Gata3 has a critical role in regulating Foxp3 expression and functional fitness of Tregs; however, the signal that regulates Gata3 and restricts its transactivation of Th2 cytokines in Tregs has remained unexplored. Our results identify Bcl6 as an essential transcription factor regulating Gata3 activity in Tregs. Thus, Bcl6 represents a crucial regulatory layer in the Treg functional program that is required for specific suppression of Gata3 and Th2 effector responses by Tregs.
Project description:Purpose:Bisphenol A (BPA) is found in many plastic products and is thus a common environmental endocrine disruptor. Plastic-related health problems, including allergic diseases, are attracting increasing attention. However, few experimental studies have explored the effect of BPA on allergic rhinitis (AR). We explore whether BPA was directly related to the allergic inflammation induced by ovalbumin (OVA) in AR mice. Methods:We first constructed OVA-induced mouse model, and after BPA administration, we evaluated nasal symptoms and measured the serum OVA-specific IgE levels by ELISA. Th2 and Treg-related cytokines of nasal mucosa were measured by cytometric bead array. Th2 and Treg-specific transcription factor levels were assayed by PCR. The proportions of CD3+CD4+IL-4+Th2 and CD4+Helios+Foxp3+ T cells (Tregs) in spleen tissue were determined by flow cytometry. Results:Compared to OVA-only-induced mice, BPA addition increased nasal symptoms and serum OVA-specific IgE levels. OVA and BPA coexposure significantly increased IL-4 and IL-13 protein levels compared to those after OVA exposure alone. BPA plus OVA tended to decrease the IL-10 protein levels compared to those after OVA alone. Coexposure to OVA and BPA significantly increased the GATA-3-encoding mRNA level, and decreased the levels of mRNAs encoding Foxp3 and Helios, compared to those after OVA exposure alone. BPA increased the Th2 cell proportion, and decreased that of Tregs, compared to the levels with OVA alone. Conclusion:BPA exerted negative effects by exacerbating AR allergic symptoms, increasing serum OVA-specific IgE levels, and compromising Th2 and Treg responses.
Project description:The beneficial effects of probiotics have been described in allergic sensitization and diseases; however, many questions remain unanswered, such as characteristics of the most effective strains in modulation of allergic responses and how orally administered probiotics affect the systemic immune system. In the present work, oral administration of five lactic acid bacteria strains showed variable effects on protection against the allergic reaction in a mouse model of food allergy to shrimp tropomyosin (ST). The most effective anti-allergic strain, Bacillus coagulans 09.712 (Bc), greatly improved epithelial barrier function and increased lymphocytes proliferation. Moreover, Bc suppresses ST sensitization by altering Th1/Th2/Treg balance as a result of strong induction of CD4+Foxp3+Tregs in combination with IL-10 producing. Bc-specific induction of CD4+Foxp3+ Tregs also suppresses Th17 pro-inflammatory response in this mouse model. Finally, the intake of Bc suppresses mTOR activation and thus the phosphorylation of downstream factors. Inhibition of mTOR signaling by Bc further results in FOXP3 up-regulation and GATA-3 down-regulation, which, in turn, facilitate to control Th2-predominant and Th17 pro-inflammatory responses caused by ST. Our work provides further characterization of the anti-allergic effects of probiotic LAB strains, and identifies new targets for preventive and curative treatment of food allergies.
Project description:Multiple factors interact to trigger allergic diseases, including individual genetic background and factors related to the environment such as exposure to allergens, air pollution and respiratory infections. The FOXP3 transcription factor is constitutively expressed in CD4+CD25+FOXP3+ regulatory T cells (Tregs) and is critical for the maintenance of immune homeostasis. For example, FOXP3 is responsible for the suppression of the Th2 response following exposure to allergens. Studies have shown that expression of the FOXP3 gene is reduced in patients with asthma and allergies compared to healthy controls. Therefore, the impairment of FOXP3 function caused by genetic polymorphisms and/or epigenetic mechanisms may be involved in the etiology of asthma and other allergic diseases. This review discusses some aspects of the role of FOXP3 in the development of asthma and allergy, with a particular emphasis on genetic and epigenetic factors.
Project description:Regulatory T cells (Tregs) play a critical role in the maintenance of airway tolerance. We report that inhaled soluble Ag induces adaptive Foxp3(+) Tregs, as well as a regulatory population of CD4(+) T cells in the lungs and lung-draining lymph nodes that express latency-associated peptide (LAP) on their cell surface but do not express Foxp3. Blocking the cytokine IL-10 or TGF-? prevented the generation of LAP(+) Tregs and Foxp3(+) Tregs in vivo, and the LAP(+) Tregs could also be generated concomitantly with Foxp3(+) Tregs in vitro by culturing naive CD4(+) T cells with Ag and exogenous TGF-?. The LAP(+) Tregs strongly suppressed naive CD4(+) T cell proliferation, and transfer of sorted OVA-specific LAP(+) Tregs in vivo inhibited allergic eosinophilia and Th2 cytokine expression in the lung, either when present at the time of Th2 sensitization or when injected after Th2 cells were formed. Furthermore, inflammatory innate stimuli from house dust mite extract, nucleotide-binding oligomerization domain containing 2 ligand, and LPS, which are sufficient for blocking airway tolerance, strongly decreased the induction of LAP(+) Tregs. Taken together, we concluded that inducible Ag-specific LAP(+) Tregs can suppress asthmatic lung inflammation and constitute a mediator of airway tolerance together with Foxp3(+) Tregs.
Project description:A reproducible method to inhibit allergic immune responses is accomplished with hi-dose Ag sensitization, via intraperitoneal (IP) injection. However, the role of CD4+ CD25+ FoxP3+ T regulatory cells (Treg) in this process is unknown, as is whether such modulation extends to ocular allergy. We therefore determined herein whether hi-dose sensitization modulates ocular allergy, and whether CD4+ CD25+ FoxP3+ Treg are involved. C57BL/6 mice were IP sensitized via low-dose (100 µg) versus hi-dose (1000 µg) ovalbumin (OVA), in aluminum hydroxide (1 mg) and pertussis-toxin (300 ng). Other mice received anti-CD25 Ab (PC61) to ablate Treg during sensitization. In another experiment, Treg from hi-dose sensitized mice were adoptively transferred into low-dose sensitized mice. Once daily OVA challenges were administered. Clinical signs, IgE, T cell cytokines, and eosinophils were assessed. Data revealed that hi-dose, but not low-dose, sensitization led to allergy modulation, indicated by decreased clinical signs, serum IgE levels, Th2 recall responses, and eosinophil recruitment. T cells from hi-dose sensitized mice showed a robust increase in TGF-b production, and Treg from these mice were able to efficiently suppress effector T cell proliferation in vitro. In addition, in vivo Treg ablation in hi-dose sensitized mice revoked allergy modulation. Lastly, Treg from hi-dose sensitized mice were able to adoptively transfer allergy modulation to their low-dose sensitized counterparts. Collectively, these findings indicate that modulation to hi-dose sensitization, which is extended to ocular allergy, occurs in a Treg-dependent manner. In addition, our data suggest that hi-dose sensitization may henceforth facilitate the further examination of CD4+ CD25+ FoxP3+ Treg in allergic disease.
Project description:<h4>Objective</h4>Anaphylaxis is a life-threatening outcome of immediate-type hypersensitivity to allergen, consecutive to mast cell degranulation by allergen-specific IgE. Regulatory T cells (Treg) can control allergic sensitization and mast cell degranulation, yet their clinical benefit on anaphylactic symptoms is poorly documented. Here we investigated whether Treg action during the effector arm of the allergic response alleviates anaphylaxis.<h4>Methods</h4>We used a validated model of IgE-mediated passive systemic anaphylaxis, induced by intravenous challenge with DNP-HSA in mice passively sensitized with DNP-specific IgE. Anaphylaxis was monitored by the drop in body temperature as well as plasma histamine and serum mMCP1 levels. The role of Treg was analyzed using MHC class II-deficient (A?(°/°)) mice, treatment with anti-CD25 or anti-CD4 mAbs and conditional ablation of Foxp3(+) Treg in DEREG mice. Therapeutic efficacy of Treg was also evaluated by transfer experiments using FoxP3-eGFP knock-in mice.<h4>Results</h4>Anaphylaxis did not occur in mast cell-deficient W/W(v) mutant mice and was only moderate and transient in mice deficient for histamine receptor-1. Defects in constitutive Treg, either genetic or induced by antibody or toxin treatment resulted in a more severe and/or sustained hypothermia, associated with a rise in serum mMCP1, but not histamine. Adoptive transfer of Foxp3(+) Treg from either naïve or DNP-sensitized donors similarly alleviated body temperature loss in Treg-deficient DEREG mice.<h4>Conclusion</h4>Constitutive Foxp3(+) Treg can control the symptomatic phase of mast cell and IgE-dependent anaphylaxis in mice. This might open up new therapeutic avenues using constitutive rather than Ag-specific Treg for inducing tolerance in allergic patients.