Objetivo: Avaliar o teste de contato atópico (TCA) em pacientes com alergia ao leite de vaca (APLV) IgE mediada - grupo 1 e naqueles com doenças eosinofílicas do trato digestório (DETD) - grupo 2, comparando os extratos de leite de vaca (LV) a 20% com o leite in natura, o tempo ideal de oclusão do teste e o valor preditivo positivo do TCA na identificação do leite como desencadeante no grupo 2, avaliada pela melhora clinica e endoscópica após dieta de restrição. Métodos: Estudo de corte transversal, com avaliação de 45 pacientes e 9 controles. O grupo 1 (n=15) com APLV IgE mediada foram diagnosticados pelo teste de provocação e prick teste positivo para LV e o grupo 2 (n=30) pela biópsia mostrando esofagite eosinofílica (15 eosinófilos/cga) ou enterocolite eosinofílica (>20 eosinófilos/cga), prick teste positivo para LV (n=15) e sintomas desencadeados pelo leite. O grupo 3 (n=9) incluiu pacientes com exclusão do diagnóstico de APLV. Utilizou-se câmaras de 12mm e LV in natura e LV a 20% como extratos ( IPI ASAC, Espanha). Os tempos de leitura foram de 24, 48 e 72 horas e considerou-se como TCA positivo, a presença de hiperemia com infiltração e formação de pápulas ou vesículas. Para avaliação do valor preditivo positivo do TCA, considerou-se pacientes com DETD com sintomas associados ao leite, sem melhora com tratamento adequado, IgE específica ao LV e melhora clínica e histológica com a instituição da dieta de restrição. Resultados: Considerando ambos os extratos, houve semelhança quanto à frequência de positividade do TCA nos três tempos de leitura em ambas situações clínicas. Com relação à concordância entre os tempos de leitura do TCA com ambos extratos, observou-se diferença estatisticamente significante entre o tempo de 24 hs com aqueles de 48 e 72hs (p=0,031 em ambas comparações), o mesmo não ocorrendo entre o tempo de 48 e 72hs tanto na APLV como nas DETD. Isoladamente, o LV a 20% mostrou comportamento semelhante em ambas as doenças, com diferença entre o tempo de 24 e aqueles de 48 (p=0,031 / 0,000) e 72hs (p=0,031/ 0,002) respectivamente na APLV e DETD. O extrato de leite in natura nos pacientes com APLV não mostrou diferença estatisticamente significante entre os tempos avaliados, enquanto nos pacientes com DETD observou-se diferença entre 24 hs e os tempos de 48hs (p=0,003) e 72hs (p=0,003). A restrição dietética do leite naqueles pacientes com DETD e TCA positivo foi associada à melhora clínica em 80% dos pacientes e associação com melhora histológica em 65% destes. Conclusões: O TCA utilizando tanto LV in natura como extrato LV a 20%, com leitura após 48 ou 72hs da sua aplicação mostrou-se útil na identificação de pacientes com DETD desencadeada pelo LV. A instituição de dieta restrita neste alimento contribuiu para a melhora dos sintomas e para a redução do número de eosinófilos na biópsia de controle / Objective: To evaluate the atopic patch test (APT) in IgE mediated cow\'s milk allergic patients (CMA) - Group 1 and those with gastrointestinal eosinophilic diseases (GED) - Group 2, comparing extracts of cow\'s milk (CM) 20% protein concentration and fresh milk, the optimal time reading and the positive predictive value of APT in the identification of milk as a trigger food in the group 2, as assessed by clinical and endoscopic improvement after dietary restriction. Methods: Cross-sectional study with evaluation of 45 patients and 9 controls. The group 1 (n = 15) with IgE-mediated CMA was diagnosed by provocation test and positive skin prick test for CM in all patients and group 2 (n = 30) by biopsy showing eosinophilic esophagitis ( 15 eosinophils / hpf) or eosinophilic enterocolitis (> 20 eosinophils / hpf ), prick test positive for CM (n = 15) and symptoms triggered by milk. Group 3 (n = 9) included patients which CMA was excluded. It was used 12mm a plastic chamber of inert material, and as extracts the fresh milk and CM at 20% (IPI ASAC, Spain). The reading times were 24, 48 and 72 hours and was considered as APT positive, the presence of hyperemia with infiltration and papules or vesicles. To evaluate the positive predictive value of the APT, it was considered GED patients with symptoms associated to milk, no response to treatment, specific IgE to CM and clinical and histological improvement after the restricted diet institution. Results: Considering both extract, there was similarity in the frequency of positive APT evaluating all the reading times in both clinical situations. Regarding the agreement between the reading times with both extracts, there was a statistically significant difference between the time of 24 hours with those of 48 and 72 hours (p = 0.031 for both comparisons). This fact was not observed between the time of 48 and 72 hours in both diseases. The CM 20% extract showed a similar pattern in both diseases, with difference between the reading time of 24 with the 48 hours (p = 0.031/0.000) and 72 hours (p = 0.031/ 0.002) respectively in both diseases. The fresh milk extract in CMA patients showed no statistically significant difference between the reading times evaluated, while in GED patients it was observed difference between 24 hours with the time of 48 hours (p = 0.003) and 72 hours (p = 0.003). The milk restricted diet for GED patients with positive APT was associated to clinical improvement in 80% of patients and in both clinical and histological response in 65% of them. Conclusions: The APT using both fresh CM and CM 20% extract with reading time of 48 or 72 hours showed useful in identifying GED patients triggered by CM. The establishment of milk restricted diet contributed to the improvement of symptoms and to reduce the number of eosinophils in the control biopsy

Objetivo: Avaliar o teste de contato atópico (TCA) em pacientes com alergia ao leite de vaca (APLV) IgE mediada - grupo 1 e naqueles com doenças eosinofílicas do trato digestório (DETD) - grupo 2, comparando os extratos de leite de vaca (LV) a 20% com o leite in natura, o tempo ideal de oclusão do teste e o valor preditivo positivo do TCA na identificação do leite como desencadeante no grupo 2, avaliada pela melhora clinica e endoscópica após dieta de restrição. Métodos: Estudo de corte transversal, com avaliação de 45 pacientes e 9 controles. O grupo 1 (n=15) com APLV IgE mediada foram diagnosticados pelo teste de provocação e prick teste positivo para LV e o grupo 2 (n=30) pela biópsia mostrando esofagite eosinofílica (15 eosinófilos/cga) ou enterocolite eosinofílica (>20 eosinófilos/cga), prick teste positivo para LV (n=15) e sintomas desencadeados pelo leite. O grupo 3 (n=9) incluiu pacientes com exclusão do diagnóstico de APLV. Utilizou-se câmaras de 12mm e LV in natura e LV a 20% como extratos ( IPI ASAC, Espanha). Os tempos de leitura foram de 24, 48 e 72 horas e considerou-se como TCA positivo, a presença de hiperemia com infiltração e formação de pápulas ou vesículas. Para avaliação do valor preditivo positivo do TCA, considerou-se pacientes com DETD com sintomas associados ao leite, sem melhora com tratamento adequado, IgE específica ao LV e melhora clínica e histológica com a instituição da dieta de restrição. Resultados: Considerando ambos os extratos, houve semelhança quanto à frequência de positividade do TCA nos três tempos de leitura em ambas situações clínicas. Com relação à concordância entre os tempos de leitura do TCA com ambos extratos, observou-se diferença estatisticamente significante entre o tempo de 24 hs com aqueles de 48 e 72hs (p=0,031 em ambas comparações), o mesmo não ocorrendo entre o tempo de 48 e 72hs tanto na APLV como nas DETD. Isoladamente, o LV a 20% mostrou comportamento semelhante em ambas as doenças, com diferença entre o tempo de 24 e aqueles de 48 (p=0,031 / 0,000) e 72hs (p=0,031/ 0,002) respectivamente na APLV e DETD. O extrato de leite in natura nos pacientes com APLV não mostrou diferença estatisticamente significante entre os tempos avaliados, enquanto nos pacientes com DETD observou-se diferença entre 24 hs e os tempos de 48hs (p=0,003) e 72hs (p=0,003). A restrição dietética do leite naqueles pacientes com DETD e TCA positivo foi associada à melhora clínica em 80% dos pacientes e associação com melhora histológica em 65% destes. Conclusões: O TCA utilizando tanto LV in natura como extrato LV a 20%, com leitura após 48 ou 72hs da sua aplicação mostrou-se útil na identificação de pacientes com DETD desencadeada pelo LV. A instituição de dieta restrita neste alimento contribuiu para a melhora dos sintomas e para a redução do número de eosinófilos na biópsia de controle / Objective: To evaluate the atopic patch test (APT) in IgE mediated cow\'s milk allergic patients (CMA) - Group 1 and those with gastrointestinal eosinophilic diseases (GED) - Group 2, comparing extracts of cow\'s milk (CM) 20% protein concentration and fresh milk, the optimal time reading and the positive predictive value of APT in the identification of milk as a trigger food in the group 2, as assessed by clinical and endoscopic improvement after dietary restriction. Methods: Cross-sectional study with evaluation of 45 patients and 9 controls. The group 1 (n = 15) with IgE-mediated CMA was diagnosed by provocation test and positive skin prick test for CM in all patients and group 2 (n = 30) by biopsy showing eosinophilic esophagitis ( 15 eosinophils / hpf) or eosinophilic enterocolitis (> 20 eosinophils / hpf ), prick test positive for CM (n = 15) and symptoms triggered by milk. Group 3 (n = 9) included patients which CMA was excluded. It was used 12mm a plastic chamber of inert material, and as extracts the fresh milk and CM at 20% (IPI ASAC, Spain). The reading times were 24, 48 and 72 hours and was considered as APT positive, the presence of hyperemia with infiltration and papules or vesicles. To evaluate the positive predictive value of the APT, it was considered GED patients with symptoms associated to milk, no response to treatment, specific IgE to CM and clinical and histological improvement after the restricted diet institution. Results: Considering both extract, there was similarity in the frequency of positive APT evaluating all the reading times in both clinical situations. Regarding the agreement between the reading times with both extracts, there was a statistically significant difference between the time of 24 hours with those of 48 and 72 hours (p = 0.031 for both comparisons). This fact was not observed between the time of 48 and 72 hours in both diseases. The CM 20% extract showed a similar pattern in both diseases, with difference between the reading time of 24 with the 48 hours (p = 0.031/0.000) and 72 hours (p = 0.031/ 0.002) respectively in both diseases. The fresh milk extract in CMA patients showed no statistically significant difference between the reading times evaluated, while in GED patients it was observed difference between 24 hours with the time of 48 hours (p = 0.003) and 72 hours (p = 0.003). The milk restricted diet for GED patients with positive APT was associated to clinical improvement in 80% of patients and in both clinical and histological response in 65% of them. Conclusions: The APT using both fresh CM and CM 20% extract with reading time of 48 or 72 hours showed useful in identifying GED patients triggered by CM. The establishment of milk restricted diet contributed to the improvement of symptoms and to reduce the number of eosinophils in the control biopsy

Esofagite Eosinofílica é uma doença inflamatória crônica restrita ao esôfago e imune mediada por antígenos. Sua prevalência descrita varia desde 0,4%, numa população geral, até 15% em pacientes com sintomas de disfagia. Já se conhece sua associação com doenças atópicas, anafilaxia e alergia alimentar, sendo o leite de vaca um dos principais alimentos envolvidos. Existem relatos recentes de casos em que pacientes foram diagnosticados com esofagite eosinofílica após serem submetidos à imunoterapia oral com o alimento causador de sua alergia alimentar mediada por IgE. Porém, em nenhum destes casos foi avaliado previamente se os mesmos pacientes já não apresentavam eosinofilia esofágica latente e/ou sintomas subjetivos sugestivos da doença. Considerando que, atualmente, um dos tratamentos mais promissores para alergia alimentar é a imunoterapia oral, justificou-se a necessidade de entender se esofagite eosinofílica seria de fato uma complicação do tratamento, ou se seria uma condição pré ou coexistente. Portanto, o objetivo deste trabalho foi avaliar a frequência de eosinofilia esofágica em pacientes com anafilaxia à proteína do leite de vaca. Foram analisados 89 pacientes matriculados no ambulatório de alergia alimentar do HC-FMUSP, com mediana de idade de 8 anos e que apresentavam anafilaxia ao leite de vaca. Todos foram submetidos à endoscopia digestiva alta com biópsias de esôfago, estomago e duodeno. Dados demográficos, comorbidades atópicas, uso de medicações e sintomas gastrointestinais foram analisados e comparados. A frequência de eosinofilia esofágica foi de 38,2% (34 de 89 pacientes). Em 15 dos 34 pacientes com eosinofilia esofágica, foi completada a investigação para esofagite eosinofílica com uso de inibidor de bomba de prótons em dose plena por 8 semanas antes de uma segunda endoscopia. Identificou-se, portanto, cinco pacientes (7,1%) com eosinofilia esofágica responsiva a inibidor de bomba de prótons e 10 pacientes com esofagite eosinofílica (14,2%). No grupo total de pacientes com eosinofilia esofágica (n=34) encontrou-se 29,4% de pacientes com quadro clínico gastrointestinal ausente; 23,5% oligossintomáticos, e apenas 47% com sintomas sugestivos de disfunção esofágica e, destes últimos, nem todos apresentavam sintomas esofágicos persistentes. Pode-se concluir que a frequência de esofagite eosinofílica descrita no grupo estudado foi significativamente superior à estimada na população geral e uma das mais altas descritas em grupos de pacientes com fatores de risco específicos. Também foi observada uma grande parcela de pacientes com eosinofilia esofágica, sendo muitos assintomáticos ou oligossintomáticos, surgindo o questionamento se esta não seria uma doença latente, de início precoce, insidioso e não relacionada diretamente como complicação de tratamentos atuais / Eosinophilic esophagitis is a chronic inflammatory disease, which occurs in the esophagus and is immune mediated by antigens. Its observed prevalence varies between 0.4% in the general population to 15% in patients with dysphagia. Its association with atopic diseases, anaphylaxis and food allergy has already been recognized. Cow\'s milk is one of the main food sources involved. There are recent reports of cases in which patients were diagnosed with eosinophilic esophagitis after being submitted to oral immunotherapy with the food that causes the IgE mediated allergy. However, in none of these cases was it previously determined if the same patients did not already present latent esophageal eosinophilia and/or subjective symptoms suggestive of the disease. Considering that, currently, one of the most promising treatment for food allergy is oral immunotherapy, the need to understand if eosinophilic esophagitis could be a treatment complication, or if it is a coexistent or preexistent condition, is justified. Therefore, the objective of this study was to evaluate esophageal eosinophilia frequency in patients with anaphylaxis to cow\'s milk protein. We analyzed eighty-nine patients registered in the Food Allergy Unit of the HCFMUSP, with a median age of 8 years, who presented cow\'s milk anaphylaxis. All of them were submitted to digestive endoscopy as well as esophagus, stomach, and duodenum biopsies. We also analyzed and compared demographic data, atopic comorbidities, use of medication, and gastrointestinal symptoms. The frequency of esophageal eosinophilia was 38.2% (34 of 89 patients). In 15 of the 34 patients with esophageal eosinophilia, full investigation for the disease was carried out using a proton pump inhibitor at full dose for eight weeks prior to a second endoscopy. From this, five patients (7.1%) had the proton pump inhibitor-responsive esophageal eosinophilia phenotype, and ten patients were diagnosed with eosinophilic esophagitis (14.2%). In the whole group of patients with esophageal eosinophilia (n = 34), it was found 29.4% of patients with an absent gastrointestinal clinical condition, 23.5% were oligosymptomatic, and only 47% had symptoms suggestive of esophagic dysfunction. Of these, not all presented persistent esophagic symptoms. It is possible to conclude that the frequency of eosinophilic esophagitis observed in this group was significantly higher than the estimated for the general population, and one of the highest observed in groups of patients with specific risk factors. A large portion of patients with esophageal eosinophilia were oligosymptomatic or asymptomatic, raising the question if this would not in fact be a latent disease, with a precocious beginning, insidious and not directly related to current treatments complications

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-04-26T15:54:34Z No. of bitstreams: 1 klausrubackbertges.pdf: 2812002 bytes, checksum: 85312f3aa11372affe21388fe45dce43 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-04-27T11:52:01Z (GMT) No. of bitstreams: 1 klausrubackbertges.pdf: 2812002 bytes, checksum: 85312f3aa11372affe21388fe45dce43 (MD5) / Made available in DSpace on 2018-04-27T11:52:01Z (GMT). No. of bitstreams: 1 klausrubackbertges.pdf: 2812002 bytes, checksum: 85312f3aa11372affe21388fe45dce43 (MD5) Previous issue date: 2018-03-21 / A esofagite eosinofílica vem tendo uma importância crescente na literatura médica. É uma doença inflamatória crônica, imunoantígeno mediada, caracterizada por sintomas de disfunção esofágica e uma infiltração predominantemente eosinofílica na mucosa do esôfago. O diagnóstico histopatológico é definido pela presença de 15 ou mais eosinófilos por campo de grande aumento e o tratamento de cada paciente deve ser individualizado. O processo de remodelamento do esôfago na esofagite eosinofílica ainda não está completamente esclarecido, mas parece envolver a presença de fibrose na lâmina própria, sendo a grande responsável pelos sintomas de disfagia e impactação alimentar. A IL-13 contrarregula a expressão de filagrina nas células epiteliais, promovendo um mecanismo pelo qual antígenos alimentares ativam o sistema imunológico. Este estudo objetivou avaliar a prevalência das características histopatológicas de remodelamento tecidual e a expressão da filagrina em biópsias esofágicas de pacientes com esofagite eosinofílica. Foram avaliadas, retrospectivamente, 50 pacientes com suspeita clínica e/ou endoscópica de esofagite eosinofílica. Deste total, 27 foram selecionados e distribuídos em dois grupos: GI, com 15 a 24 eosinófilos por campo de grande aumento e GII, contendo mais de 24. Após a histomorfometria e imuno-histoquímica para filagrina, comparou-se os dois grupos. Nos parâmetros de fibrose, houve diferença estatisticamente significante, com maior prevalência no GII (p < 0,05). Também houve mais espessamento da camada basal no GII (p < 0,001). No estudo de correlação entre o número de eosinófilos e o percentual de fibrose, encontrou-se correlação positiva: 50,8% (p = 0,016), ou seja, mais fibrose nos casos do GII. Na correlação entre o número de eosinófilos e a espessura da camada basal, o resultado também foi positivo: 52,1% (p = 0,08), ou seja, membrana basal mais espessa no GII. A filagrina mostrou-se reduzida nos pacientes com esofagite eosinofílica. / Eosinophilic esophagitis is of increasing importance in the medical literature. It is a chronic inflammatory disease, mediated immunoantigen, characterized by symptoms of esophageal dysfunction and a predominantly eosinophilic infiltration in the esophagic mucosa. The histopathological diagnosis is defined by the presence of 15 or more eosinophils per large increase field and the treatment of each patient should be individualized. The process of esophageal remodeling into eosinophilic esophagitis is still not fully understood, but it seems to involve a presence of fibrosis in the lamina propria, being a major cause of the symptoms of dysphagia and food impaction. IL-13 counteracts the expression of filaggrin in epithelial cells, promoting a mechanism by which food antigens activate the immune system. This study aimed to evaluate a prevalence of the histopathological characteristics of tissue remodeling and the filaggrin expression in esophageal biopsies of patients with eosinophilic esophagitis. Fifty patients with clinical and/or endoscopic suspicion of eosinophilic esophagitis were retrospectively evaluated. Of these, 27 were selected and distributed in two groups: GI, with 15 to 24 eosinophils per large increase field and GII, containing more than 24. After a histomorphometry and immunohistochemistry for filaggrin, the two groups were compared. In the fibrosis parameters, there was a statistically significant difference, with a higher prevalence in GII (p < 0.05). There was also more thickening of the basal layer in GII (p < 0.001). The correlation study between the number of eosinophils and the percentage of fibrosis found a positive correlation: 50.8% (p = 0.016), that means, more fibrosis in cases of GII. In the correlation between the number of eosinophils and the thickness of the basal layer, the result was also positive: 52.1% (p = 0.08), that means, thicker basal layer in GII. Filaggrin was reduced in patients with eosinophilic esophagitis.

Les maladies immunitaires chroniques incluant les maladies auto-immunes et inflammatoires touchent 20 à 25% de la population des pays occidentaux. La comparaison des taux de concordance chez les jumeaux ou l’histoire familiale de sujets atteints de la maladie cœliaque (maladie auto-immune de l’intestin) ou de l’œsophagite éosinophilique (maladie inflammatoire de l’œsophage) indiquent que des facteurs génétiques et environnementaux interviennent dans la susceptibilité à ces maladies. Cependant, ces études ne distinguent pas de manière claire la prédisposition génétique selon l’hétérogénéité clinique (enfants versus adultes) ou ethnique (stratification des populations). Méthodes. Les haplotypes HLA de prédisposition à la maladie cœliaque et les polymorphismes des gènes candidats IL-13 (R130Q), IL-5 (-746 T/G) et IL-5R (-80A/G) impliqués dans la physiopathologie de l’œsophagite éosinophilique, ont été caractérisés par la technique PCR-SSP sur l’ADN génomique. Résultats: Nos études familiales et cas-contrôles réalisées chez une population Québécoises avec un fond génétique très homogène nous a permis : i) d’éviter le problème de stratification des populations, ii) de confirmer que les gènes HLA sont également associés à la maladie cœliaque (enfants et adultes) au Québec comme dans les autres populations Caucasiennes, iii) de mettre en évidence le rôle du gène IL-13 dans la prédisposition à l’œsophagite éosinophilique (garçons et filles) et d’exclure les gènes IL-5 et IL-5R comme facteurs de susceptibilité dans notre population. Conclusion: Ce travail confirme pour la première fois l’impact des gènes HLA dans la prédisposition à la maladie cœliaque et le rôle du facteur génétique dans l’œsophagite éosinophilique chez une population Canadienne Française avec un fond génétique ayant un fort effet fondateur. / Chronic immune diseases including autoimmune and inflammatory diseases affect 20 to 25% of Western country population. The higher concordance of disease in twins or in first-degree relative of patients with celiac disease (bowel autoimmune disease) or eosinophilic esophagitis (inflammatory disease of the esophagus) indicate that genetic and environmental factors are involved in susceptibility to these diseases. However, these studies do not distinguish clearly genetic predisposition according to clinical heterogeneity (children versus adults) or ethnicity (population stratification). Methods: HLA haplotypes predisposing to celiac disease and polymorphisms of candidate genes IL-13 (R130Q), IL-5 (-746 T / G) and IL-5R (-80A / G) involved in physiopathology of eosinophilic esophagitis, have been evaluated by PCR-SSP on genomic DNA. Results: Our familial and case-control studies performed in populations having a very similar genetic background with a strong founder effect, allowed us: i) to avoid the problem of population stratification, ii) to confirm that HLA genes are also associated with celiac disease in Quebec (children and adults) as in other Caucasian populations, iii) to identify the role of IL-13 gene in susceptibility to eosinophilic esophagitis (boys and girls) and to exclude IL-5 and IL-5R genes as susceptibility factor in our population. Conclusion: This study confirms for the first time the impact of HLA genes in predisposition to celiac disease and the role of genetic factors in eosinophilic esophagitis in a French Canadian population with a strong founder effect.

Indiana University-Purdue University Indianapolis (IUPUI) / Regulatory T (Treg) cells represent an important layer of immune-regulation indispensible for curtailing exuberant inflammatory responses and maintaining self-tolerance. Treg cells have translational potential for autoimmunity, inflammation, transplantation and cancer. Therefore, delineating the molecular underpinnings underlying the development, suppressor function and stability of Tregs is particularly warranted. The transcriptional repressor Bcl6 is a critical arbiter of helper T cell fate, promoting the follicular helper (Tfh) lineage while repressing Th1, Th2 and Th17 differentiation. Bcl6-deficient mice develop a spontaneous and severe Th2-type inflammatory disease including myocarditis and pulmonary vasculitis, suggesting a potential role for Bcl6 in Treg cell function. Bcl6-deficient Treg cells are competent in controlling Th1 responses, but fail to control Th2 inflammation in an airway allergen model. Importantly, mice with Bcl6 deleted specifically in the Treg lineage develop severe myocarditis, thus highlighting a critical role for Bcl6 in Treg-mediated control of Th2 inflammation. Bcl6-deficient Tregs display an intrinsic increase in Th2 genes and microRNA-21 (miR-21) expression. MiR-21 is a novel Bcl6 gene target in T cells and ectopic expression of miR-21 directs Th2 differentiation in non-polarized T cells. MiR-21 is up-regulated in mouse models of airway inflammation and also in human patients with eosinophilic esophagitis and asthma. Thus, miR-21 is a clinically relevant biomarker for Th2-type pathologies. Our results define a key function for Bcl6 in repressing Gata3 function and miR-21 expression in Tregs, and provide greater understanding of the control of Th2 inflammatory responses by Treg cells.