Regulatory T Cells Accumulate in the Lung Allergic Inflammation and Efficiently Suppress T-Cell Proliferation but Not Th2 Cytokine Production

Foxp3+CD25+CD4+ regulatory T cells are vital for peripheral tolerance and control of tissue inflammation. In this study, we characterized the phenotype and monitored the migration and activity of regulatory T cells present in the airways of allergic or tolerant mice after allergen challenge. To induce lung allergic inflammation, mice were sensitized twice with ovalbumin/aluminum hydroxide gel and challenged twice with intranasal ovalbumin. Tolerance was induced by oral administration of ovalbumin for 5 consecutive days prior to OVA sensitization and challenge. We detected regulatory T cells (Foxp3+CD25+CD4+ T cells) in the airways of allergic and tolerant mice; however, the number of regulatory T cells was more than 40-fold higher in allergic mice than in tolerant mice. Lung regulatory T cells expressed an effector/memory phenotype (CCR4highCD62LlowCD44highCD54highCD69+) that distinguished them from naive regulatory T cells (CCR4intCD62LhighCD44intCD54intCD69−). These regulatory T cells efficiently suppressed pulmonary T-cell proliferation but not Th2 cytokine production

Regulatory T Cells Accumulate in the Lung Allergic Inflammation and Efficiently Suppress T-Cell Proliferation but Not Th2 Cytokine Production

Foxp3+CD25+CD4+ regulatory T cells are vital for peripheral tolerance and control of tissue inflammation. In this study, we characterized the phenotype and monitored the migration and activity of regulatory T cells present in the airways of allergic or tolerant mice after allergen challenge. To induce lung allergic inflammation, mice were sensitized twice with ovalbumin/aluminum hydroxide gel and challenged twice with intranasal ovalbumin. Tolerance was induced by oral administration of ovalbumin for 5 consecutive days prior to OVA sensitization and challenge. We detected regulatory T cells (Foxp3+CD25+CD4+ T cells) in the airways of allergic and tolerant mice; however, the number of regulatory T cells was more than 40-fold higher in allergic mice than in tolerant mice. Lung regulatory T cells expressed an effector/memory phenotype (CCR4highCD62LlowCD44highCD54highCD69+) that distinguished them from naive regulatory T cells (CCR4intCD62LhighCD44intCD54intCD69−). These regulatory T cells efficiently suppressed pulmonary T-cell proliferation but not Th2 cytokine production

Inhibitory Receptors Are Expressed by Trypanosoma cruzi-Specific Effector T Cells and in Hearts of Subjects with Chronic Chagas Disease

We had formerly demonstrated that subjects chronically infected with Trypanosoma cruzi show impaired T cell responses closely linked with a process of T cell exhaustion. Recently, the expression of several inhibitory receptors has been associated with T cell dysfunction and exhaustion. In this study, we have examined the expression of the cytotoxic T lymphocyte antigen 4 (CTLA-4) and the leukocyte immunoglobulin like receptor 1 (LIR-1) by peripheral T. cruzi antigen-responsive IFN-gamma (IFN-γ)-producing and total T cells from chronically T. cruzi-infected subjects with different clinical forms of the disease. CTAL-4 expression was also evaluated in heart tissue sections from subjects with severe myocarditis. The majority of IFN-γ-producing CD4+ T cells responsive to a parasite lysate preparation were found to express CTLA-4 but considerably lower frequencies express LIR-1, irrespective of the clinical status of the donor. Conversely, few IFN-γ-producing T cells responsive to tetanus and diphtheria toxoids expressed CTLA-4 and LIR-1. Polyclonal stimulation with anti-CD3 antibodies induced higher frequencies of CD4+CTAL-4+ T cells in patients with severe heart disease than in asymptomatic subjects. Ligation of CTLA-4 and LIR-1 with their agonistic antibodies, in vitro, reduces IFN-γ production. Conversely, CTLA-4 blockade did not improved IFN-γ production in response to T. cruzi antigens. Subjects with chronic T. cruzi infection had increased numbers of CD4+LIR-1+ among total peripheral blood mononuclear cells, relative to uninfected individuals and these numbers decreased after treatment with benznidazole. CTLA-4 was also expressed by CD3+ T lymphocytes infiltrating heart tissues from chronically infected subjects with severe myocarditis. These findings support the conclusion that persistent infection with T. cruzi leads to the upregulation of inhibitory receptors which could alter parasite specific T cell responses in the chronic phase of Chagas disease

T cells at the site of autoimmune inflammation show increased potential for trogocytosis

CD4+ T cells acquire membrane fragments from antigen-presenting-cells via a process termed trogocytosis. Identifying which CD4+ T cells undergo trogocytosis in co-culture with Ag-loaded APC can enrich for antigen-reactive T cells without knowledge of their fine specificity or cytokine-production profiles. We sought to assess the suitability of this method to identify disease relevant effector and regulatory T cells during autoimmune inflammation. Trogocytosis efficiently identified MBP-reactive T cells in vitro and ex-vivo following immunization. However, Foxp3+ regulatory T cells constitutively displayed a higher rate of trogocytosis than their Foxp3- counterparts which limits the potential of trogocytosis to identify antigen-reactive Treg cells. During inflammation a locally elevated rate of trogocytosis (seen in both effector and regulatory T cells isolated from the inflamed CNS) precludes the use of trogocytosis as a measure of antigenic reactivity among cells taken from inflammatory sites. Our results indicate trogocytosis detection can enrich for Ag-reactive conventional T cells in the periphery but is limited in its ability to identify Ag-reactive Treg or T effector cells at sites of inflammation. Increased trogocytosis potential at inflammatory sites also draws into the question the biological significance of this phenomenon during inflammation, in Treg mediated suppression and for the maintenance of tolerance in health and disease

Neural correlates of food allergy: role of IgE-dependent mechanisms and sensory C-fibers

Embora alguns estudos tenham considerado a possibilidade da existência de uma relação direta entre alergia alimentar e alterações de comportamento, são escassas as evidências que sustentem esta hipótese. Relatamos neste trabalho que, após desafio oral com o antígeno, camundongos sensibilizados com ovalbumina (OVA) apresentaram maiores níveis de ansiedade, maiores níveis séricos de corticosterona e aumento da imunorreatividade para Fos no núcleo paraventricular do hipotálamo (PVN) e no núcleo central da amígdala (CeA), áreas cerebrais relacionadas com emotividade. Os neurônios ativados pela alergia alimentar no PVN e no CeA são capazes de produzir fator liberador de corticotrofina (CRF). Os dados também demonstraram que a alergia alimentar leva à ativação do núcleo do trato solitário (NTS). Além disso, observamos que animais imunizados com OVA desenvolveram aversão à ingestão de uma solução contendo clara de ovo. Um tratamento com anticorpo anti-IgE ou a indução de tolerância oral bloquearam tanto o desenvolvimento da aversão à dieta contendo o antígeno quanto a expressão de c-fos no sistema nervoso central (SNC). Para investigar o modo pelo qual se dá a comunicação entre o cérebro e o intestino de animais com alergia alimentar, tratamos camundongos neonatalmente com capsaicina visando a destruição de fibras sensoriais do tipo C. O tratamento com capsaicina, embora não tenha impedido o desenvolvimento da aversão, diminuiu a sua magnitude. Ademais, este tratamento bloqueou completamente a ativação do PVN e diminuiu a expressão de c-fos induzida pela alergia alimentar no núcleo do trato solitário (NTS). Contudo, o tratamento com capsaicina não modificou a imunorreatividade para Fos no CeA de animais imunizados desafiados por via oral com o antígeno. Estes resultados demonstram claramente que a alergia alimentar influencia a atividade do SNC e o comportamento animal. Além disso, os dados obtidos evidenciam a participação de mecanismos dependentes de IgE e das fibras do tipo C na comunicação entre cérebro e o intestino de animais com alergia alimentar. De modo geral, além de enfatizar a relevância da integração entre os sistemas imune e nervoso na elaboração de respostas adaptativas, este estudo fornece subsídios para uma melhor compreensão de possíveis desordens de natureza psicológica em pacientes alérgicos.Although many authors have considered the possibility of a direct interaction between food allergy and behavioral changes, the evidence supporting this hypothesis is elusive. Here we show that after oral OVA challenge allergic mice present higher levels of anxiety, increased serum corticosterone, and increased Fos expression in the paraventricular nucleus of the hypothalamus (PVN) and in the central nucleus of the amygdala (CeA), which are both emotionality-related brain areas. Food allergy-activated neurons in the PVN and in the CeA are able to produce CRF. We found that food allergy also induced enhanced Fos immunoreactivity in the nucleus of tractus solitarii (NTS) of OVA-immunized animals. Besides that, OVA-immunized animals developed aversion to an antigen-containing solution. Treatment with anti-IgE antibody, or induction of oral tolerance abrogated both food aversion and the expression of c-fos in the central nervous system. In order to investigate the brain-gut communication in allergic animals, we have employed destruction of sensory C fibers by neonatal capsaicin treatment. Although this treatment did not block development of food aversion, it decreased the magnitude of such aversion. Moreover, we observed that while the degree of Fos staining in the NTS of allergic mice was only diminished by neonatal capsaicin, it was completely blocked in the PVN. However, capsaicin did not modify food alergy-induced c-fos expression in the CeA. Besides establishing a direct relationship between brain function and food allergy, our findings provide evidence showing that IgE-dependent mechanisms and the sensory C fibers play an important role in food allergy signaling to the mouse brain. Finally, this study creates a solid ground for understanding the etiology of psychological disorders in allergic patients

Neural correlates of food allergy: role of IgE-dependent mechanisms and sensory C-fibers

Embora alguns estudos tenham considerado a possibilidade da existência de uma relação direta entre alergia alimentar e alterações de comportamento, são escassas as evidências que sustentem esta hipótese. Relatamos neste trabalho que, após desafio oral com o antígeno, camundongos sensibilizados com ovalbumina (OVA) apresentaram maiores níveis de ansiedade, maiores níveis séricos de corticosterona e aumento da imunorreatividade para Fos no núcleo paraventricular do hipotálamo (PVN) e no núcleo central da amígdala (CeA), áreas cerebrais relacionadas com emotividade. Os neurônios ativados pela alergia alimentar no PVN e no CeA são capazes de produzir fator liberador de corticotrofina (CRF). Os dados também demonstraram que a alergia alimentar leva à ativação do núcleo do trato solitário (NTS). Além disso, observamos que animais imunizados com OVA desenvolveram aversão à ingestão de uma solução contendo clara de ovo. Um tratamento com anticorpo anti-IgE ou a indução de tolerância oral bloquearam tanto o desenvolvimento da aversão à dieta contendo o antígeno quanto a expressão de c-fos no sistema nervoso central (SNC). Para investigar o modo pelo qual se dá a comunicação entre o cérebro e o intestino de animais com alergia alimentar, tratamos camundongos neonatalmente com capsaicina visando a destruição de fibras sensoriais do tipo C. O tratamento com capsaicina, embora não tenha impedido o desenvolvimento da aversão, diminuiu a sua magnitude. Ademais, este tratamento bloqueou completamente a ativação do PVN e diminuiu a expressão de c-fos induzida pela alergia alimentar no núcleo do trato solitário (NTS). Contudo, o tratamento com capsaicina não modificou a imunorreatividade para Fos no CeA de animais imunizados desafiados por via oral com o antígeno. Estes resultados demonstram claramente que a alergia alimentar influencia a atividade do SNC e o comportamento animal. Além disso, os dados obtidos evidenciam a participação de mecanismos dependentes de IgE e das fibras do tipo C na comunicação entre cérebro e o intestino de animais com alergia alimentar. De modo geral, além de enfatizar a relevância da integração entre os sistemas imune e nervoso na elaboração de respostas adaptativas, este estudo fornece subsídios para uma melhor compreensão de possíveis desordens de natureza psicológica em pacientes alérgicos.Although many authors have considered the possibility of a direct interaction between food allergy and behavioral changes, the evidence supporting this hypothesis is elusive. Here we show that after oral OVA challenge allergic mice present higher levels of anxiety, increased serum corticosterone, and increased Fos expression in the paraventricular nucleus of the hypothalamus (PVN) and in the central nucleus of the amygdala (CeA), which are both emotionality-related brain areas. Food allergy-activated neurons in the PVN and in the CeA are able to produce CRF. We found that food allergy also induced enhanced Fos immunoreactivity in the nucleus of tractus solitarii (NTS) of OVA-immunized animals. Besides that, OVA-immunized animals developed aversion to an antigen-containing solution. Treatment with anti-IgE antibody, or induction of oral tolerance abrogated both food aversion and the expression of c-fos in the central nervous system. In order to investigate the brain-gut communication in allergic animals, we have employed destruction of sensory C fibers by neonatal capsaicin treatment. Although this treatment did not block development of food aversion, it decreased the magnitude of such aversion. Moreover, we observed that while the degree of Fos staining in the NTS of allergic mice was only diminished by neonatal capsaicin, it was completely blocked in the PVN. However, capsaicin did not modify food alergy-induced c-fos expression in the CeA. Besides establishing a direct relationship between brain function and food allergy, our findings provide evidence showing that IgE-dependent mechanisms and the sensory C fibers play an important role in food allergy signaling to the mouse brain. Finally, this study creates a solid ground for understanding the etiology of psychological disorders in allergic patients

Correction: A Human Trypanosome Suppresses CD8+ T Cell Priming by Dendritic Cells through the Induction of Immune Regulatory CD4+ Foxp3+ T Cells.

[This corrects the article DOI: 10.1371/journal.ppat.1005698.]

Pharmacological manipulation of immune-induced food aversion in rats

Background: Mice allergic to ovalbumin (OVA) avoid drinking a solution containing this antigen. This was interpreted as related to IgE-dependent mast cell degranulation and sensory C fiber activation. Methods: We employed pharmacological manipulation to further investigate the mediators involved in immune-induced food aversion. Results: While nonimmunized rats preferred a sweetened OVA solution, immunized rats avoided it. We also employed a paradigm in which rats are conditioned to drink water for two 10-min sessions a day. Tolerant rats presented lower IgE titers, and this manipulation abrogated food aversion. Dexamethasone (1.0 mg/kg) prevented the aversion of OVA-immunized rats to the antigen-containing solution. Combined blockade of H1 and 5-hydroxytryptamine (5-HT)2 receptors by promethazine (3.0 mg/kg) plus methysergide (5.0 mg/kg) was unable to alter food aversion. Blockade of 5-HT3 receptors by ondansetron (1.0 mg/kg) caused a twofold increase in the ingestion of the sweetened OVA solution by immunized rats, suggesting the involvement of 5-HT3 receptors in food aversion. Finally, we showed that dexamethasone or promethazine plus methysergide, but not ondansetron, effectively prevented the IgE-dependent mast-cell-degranulation-induced increase in vascular permeability in rats. Conclusion: We suggest that regardless of whether or not they cause edema, IgE-mediated mast cell degranulation and consequent 5-HT3 signaling are involved in the process that triggers avoidance to the source of the allergen in allergic rat

CTLA-4 and TGF-β contribute to the suppression of OTI CD8⁺ T cell priming induced by <i>T</i>. <i>cruzi</i>-exposed BMDC.

<p>a- 1 x 10⁴ OTI cells were adoptively transferred into C57BL/6 mice treated with IgG or blocking antibodies against CTLA-4 or TGF-β. These mice were transferred with 5 x 10⁵ BMDC (Gr.1), 5 x 10⁵ BMDC-SIINFEKL (Gr.2) or 5 x 10⁵ <i>T</i>. <i>cruzi</i>-exposed BMDC-SIINFEKL (Gr.3). The SIINFEKL-specific immune response was assessed after 5 days. b- The numbers of SIINFEKL-specific CD8⁺ T cells were determined by H-2K^b-SIINFEKL tetramer staining. c- Spleen cells were also restimulated <i>ex vivo</i> with SIINFEKL peptide and the numbers of TNF and/or IFN-γ-producing CD8⁺ T cells were assessed by ICS. d- The proportion of polyfunctional cells simultaneously stained for CD107a, IL-2, TNF and IFN-γ was determined by Boolean analysis. Results are one of two separate experiments expressed as individual values and the mean ± SEM of each group. Asterisks indicate significant differences between the indicated groups (*P<0.05, **P<0.01 One-way ANOVA followed by Tukey post-hoc test).</p