STAT3 activation impairs the stability of Th9 cells

Th9 cells regulate multiple immune responses including immunity to pathogens and tumors, allergic inflammation, and autoimmunity. Despite ongoing research into Th9 development and function, little is known about the stability of the Th9 phenotype. In this report we demonstrate that IL-9 production is progressively lost in Th9 cultures over several rounds of differentiation. The loss of IL-9 is not due to an outgrowth of cells that do not secrete IL-9, as purified IL-9 secretors demonstrate the same loss of IL-9 in subsequent rounds of differentiation. The loss of IL-9 production correlates with increases in phospho-STAT3 levels within the cell, and the production of IL-10. STAT3-deficient Th9 cells have increased IL-9 production that is maintained for longer in culture than IL-9 in control cultures. IL-10 is responsible for STAT3 activation during the first round of differentiation, and contributes to instability in subsequent rounds of culture. Together, our results indicate that environmental cues dictate the instability of the Th9 phenotype, and suggest approaches to enhance Th9 activity in beneficial immune responses

STAT3 Impairs STAT5 Activation in the Development of IL-9-Secreting T Cells

Th cell subsets develop in response to multiple activating signals, including the cytokine environment. IL-9-secreting T cells develop in response to the combination of IL-4 and TGF-β, although they clearly require other cytokine signals, leading to the activation of transcription factors including STAT5. In Th17 cells, there is a molecular antagonism of STAT5 with STAT3 signaling, although whether this paradigm exists in other Th subsets is not clear. In this paper, we demonstrate that STAT3 attenuates the ability of STAT5 to promote the development of IL-9-secreting T cells. We demonstrate that production of IL-9 is increased in the absence of STAT3 and cytokines that result in a sustained activation of STAT3, including IL-6, have the greatest potency in repressing IL-9 production in a STAT3-dependent manner. Increased IL-9 production in the absence of STAT3 correlates with increased endogenous IL-2 production and STAT5 activation, and blocking IL-2 responses eliminates the difference in IL-9 production between wild-type and STAT3-deficient T cells. Moreover, transduction of developing Th9 cells with a constitutively active STAT5 eliminates the ability of IL-6 to reduce IL-9 production. Thus, STAT3 functions as a negative regulator of IL-9 production through attenuation of STAT5 activation and function

Prostaglandina E2 inhibts the differentiation of Th17 cells on the context of phagocytosis of infected apoptotic cells

A fagocitose de células apoptóticas, também denominada eferocitose, é um processo dinâmico e de fundamental importância para homeostase dos tecidos após uma injúria. Estudos demonstraram previamente que a fagocitose de células apoptóticas promove a síntese de mediadores anti-inflamatórios como PGE2, TGF-? e IL-10, podendo resultar num microambiente supressor e aumento da susceptibilidade do hospedeiro contra agentes infecciosos. Entretanto, a fagocitose de células apoptóticas infectadas por células dendríticas promove a geração não apenas de citocinas anti-inflamatórias como TGF-?, mas também de IL-6 e IL-23, levando a um efeito imunoestimulador, a diferenciação de células Th17. A atuação da PGE2 na imunidade adaptativa vem sendo investigada quanto à diferenciação e ativação de linfócitos Th1, Treg e Th17. Nossos resultados demonstram que a fagocitose de células apoptóticas infectadas com E. coli promove a ativação e migração de células dendríticas, assim como a produção de citocinas pró- e anti-inflamatórias e altos níveis de PGE2. No entanto, diferente da hipótese inicial, a presença de altas concentrações de PGE2 inibe drasticamente a diferenciação de células Th17 no contexto de fagocitose de células apoptóticas infectadas com E. coli por células dendríticas, in vitro. O tratamento de linfócitos T CD4+naive com antagonistas e agonistas de EP2/EP4 demonstram que o efeito supressor de PGE2 é mediado primordialmente pelo receptor EP4. Por fim, nossos resultados in vivo comprovam os resultados obtidos in vitro, demonstrando o papel supressor de PGE2 na diferenciação de células Th17 no contexto de fagocitose de células apoptóticas infectadas em modelo de infecção pulmonar.The phagocytosis of apoptotic cells, also called efferocytosis, is a dynamic process critical for tissue homeostasis after injury. We and other groups previously have shown that phagocytosis of apoptotic cells promotes the synthesis of anti-inflammatory mediators such as PGE2, TGF-? and IL-10, that may result in the suppression of host defense against microorganisms. However, an elegant study using infected apoptotic cells showed that phagocytosis of these cells promote not only the generation of anti-inflammatory cytokines such as TGF-? but also IL-6 and IL-23, resulting in an immunostimulatory effect, the differentiation of Th17 cells. The role of PGE2 in adaptive immunity has been investigated regarding differentiation and activation of Th1, Th17 and Treg. Our results demonstrate that engulfment of E.coli infected apoptotic cells promotes the activation and migration of dendritic cells as well as production of pro and anti-inflammatory cytokines together with high levels of PGE2. However, differing from our hypothesis, high levels of PGE2 inhibits drastically the differentiation of Th17 cells on the context of engulfment of E.coli infected apoptotic cells by dendritic cells in vitro. The treatment of T CD4+naive cells with antagonist or agonists of EP2/EP4 receptors demonstrates the suppressor effect is mainly mediated by EP4 receptor. Finally, the instillation of E.coli infected apoptotic cells in E.coli infected animals resulted on modest Th17 increase but treatment with cox inhibitor increased Th17 cell differentiation. Therefore, our in vivo results prove the in vitro results

Avaliação do potencial profilático de células dendríticas transfectadas com RNA fúngico em modelo experimental de esporotricose sistêmica

A esporotricose é uma infecção micótica provocada pelo fungo dimórfico Sporothrix schenckii. Apresenta em geral lesões cutâneas nodulares e/ou ulcerativas, da qual o fungo dissemina por via linfática, provocando em alguns casos, infecção sistêmica. As células dendríticas (CDs) são células apresentadoras de antígenos profissionais, capazes de traduzir a informação associada ao fungo e promover uma resposta celular tanto in vitro quanto in vivo. Entretanto, os mecanismos envolvidos na interação entre CDs e o fungo S. schenckii ainda não foram esclarecidos. O presente estudo investigou as mudanças fenotípicas e funcionais em células dendríticas derivadas da medula óssea de camundongos, in vitro, promovidas pelos diferentes estímulos fúngicos e sua capacidade em iniciar uma resposta imune celular. Os antígenos estudados foram o exoantígeno, RNA total de levedura ou hifa, e levedura viva do fungo S. schenckii. Os resultados demonstraram que todos os estímulos foram capazes de ativar as CDs em termos de geração de uma resposta imune celular. Enquanto o grupo Levedura promoveu uma produção mais acentuada de IFN-g do que IL-17, o grupo Exo100 gerou uma produção similar entre essas citocinas. Esse resultado sugere que o exoantígeno pode ser capaz de desviar a resposta imune celular de um perfil Th1 efetor para Th17 inflamatório. O RNA obtido do fungo S. schenckii em sua forma leveduriforme foi capaz de ativar CDs, promovendo uma resposta Th1 enquanto o RNA obtido a partir da hifa promoveu resposta Th17 em 48 horas de ensaio de co-cultura. Nesse contexto, a citocina IL-12 foi essencial para a ativação de células T produtoras de IFN-g, enquanto as citocinas TGF-β e IL-6 foram necessárias para ativação de células T produtoras de IL-17. Nossos dados demonstram a plasticidade das CDs em traduzir diferentes estímulos derivados do fungo S. schenckii em uma resposta...Sporotrichosis is a disease caused by the dimorphic fungus Sporothrix schenckii. The mains clinical manifestations occur on the skin, however the number of systemic and visceral cases has increased, especially in immunocompromised patients. Dendritic cells (DC) are highly capable of recognizing the fungus associated data and translate it into differential T cells responses both in vitro and in vivo. Although, the mechanisms involved in the interaction between DCs and S. schenckii are not fully elucidated. The study aimed to investigate the phenotypic and functional changes in bone marrow dendritic cells stimulated in vitro with the yeast form, or exoantigen, or total RNA from yeast or hyphal forms, of the fungus S. schenckii and its ability to trigger a cellular immune response. Our results demonstrated that live yeast-form from S. schenckii and exoantigen, on its higher dose, were able to activate BMDC and made them fully capable of triggering T cell responses in vitro. Whereas the Yeast group promoted a more enunciated IFN-γ production than IL-17, the Exo100 group generated a similar production of both cytokines. The exoantigen stimulus suggest an ability in deviating the immune response from an effector Th1 to inflammatory Th17 response, although we do not know the effects of an increase on Th17 cells in sporotrichosis. Similarly, RNA antigens were equally capable of immunomodulation, with yeast RNA promoting a Th1 whereas hyphal RNA promoted Th17 responses at 48 hours co-culture assay. In this context, the IL-12 cytokine was shown essencial to the activation of IFN-g producing T cells, whilst TGF-β and IL-6 cytokines were shown needed for IL-17 producing T cells activation. Our data demonstrated the plasticity of DC on translating the data associated with the fungus S. schenckii and ExoAg and total RNA into differential T cells response in vitro. Further we assessed the ability of these cells on ...Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Prostaglandin E 2 and the suppression of phagocyte innate immune responses in different organs

The local and systemic production of prostaglandin E 2 (PGE 2 ) and its actions in phagocytes lead to immunosuppressive conditions. PGE 2 is produced at high levels during inflammation, and its suppressive effects are caused by the ligation of the E prostanoid receptors EP 2 and EP 4 , which results in the production of cyclic AMP. However, PGE 2 also exhibits immunostimulatory properties due to binding to EP 3 , which results in decreased cAMP levels. The various guanine nucleotide-binding proteins (G proteins) that are coupled to the different EP receptors account for the pleiotropic roles of PGE 2 in different disease states. Here, we discuss the production of PGE 2 and the actions of this prostanoid in phagocytes from different tissues, the relative contribution of PGE 2 to the modulation of innate immune responses, and the novel therapeutic opportunities that can be used to control inflammatory responses

Prostaglandin E and the Suppression of Phagocyte Innate Immune Responses in Different Organs

The local and systemic production of prostaglandin E2 (PGE2) and its actions in phagocytes lead to immunosuppressive conditions. PGE2 is produced at high levels during inflammation, and its suppressive effects are caused by the ligation of the E prostanoid receptors EP2 and EP4, which results in the production of cyclic AMP. However, PGE2 also exhibits immunostimulatory properties due to binding to EP3, which results in decreased cAMP levels. The various guanine nucleotide-binding proteins (G proteins) that are coupled to the different EP receptors account for the pleiotropic roles of PGE2 in different disease states. Here, we discuss the production of PGE2 and the actions of this prostanoid in phagocytes from different tissues, the relative contribution of PGE2 to the modulation of innate immune responses, and the novel therapeutic opportunities that can be used to control inflammatory responses