A rinossinusite crônica (RSC) é uma doença inflamatória da mucosa nasal, e pouco tem sido relacionada à exposição no ambiente de trabalho, em especial ao algodão. Atualmente, uma série de citocinas e quimiocinas tem sido estudada para elucidação das características imunológicas que levam ao desenvolvimento da doença. Objetivos: Caracterizar a exposição ao algodão como indutora de RSC e determinar o padrão de resposta inflamatória imuno-histoquímica da mucosa nasal de indivíduos expostos ou não ao algodão e que desenvolveram RSC. Casuística e Metodos: Por meio de questionário baseado no EPOS e SNOT-22 foi realizado diagnóstico clínico de RSC em indivíduos expostos ao algodão no ambiente de trabalho. Após a confirmação diagnóstica com tomografia computadorizada e nasofibroscopia flexível foi realizada biópsia na mucosa de concha média de pacientes com diagnóstico clínico de RSC para análise da expressão de IL-4, IL-5, IL-10, IL-17 e IL-33. A análise foi realizada também em grupo com RSC sem exposição ao algodão e controle sem RSC. Resultados: Todos os indivíduos expostos ao algodão com sintomatologia sugestiva de RSC apresentaram padrão histológico com aumento da expressão de IL-4, IL-5, IL-10, IL-17 e IL-33. Conclusões: O presente estudo comprovou a estreita relação entre a exposição ao algodão no ambiente de trabalho e o surgimento de uma resposta inflamatória com aumento da expressão das interleucinas estudadas. A possível instituição de terapias/medicamentos que inibissem a expressão dessas citocinas poderia auxiliar na diminuição do processo inflamatório presente na RSC e/ou no desencadeamento da doença / The chronic rhinusinusitis (CRS) is an inflammatory disease of the nasal mucosa, and has been little related to exposure in the work environment, especially to cotton. Currently, a number of cytokines and chemokines have been studied to elucidate the immunological characteristics that lead to the development of the disease. Objectives: To characterize exposure to cotton as an inducer of CRS and to determine the pattern of inflammatory immune-histochemical response of the nasal mucosa of individuals exposed or not to cotton and who developed CRS. Casuistic and Methods: Using a questionnaire based on EPOS and SNOT-22, a clinical diagnosis of CRS was performed in individuals exposed to cotton in the work environment. After diagnostic confirmation with computed tomography and flexible nasofibroscopy, biopsy was performed on the middle concha mucosa of patients with clinical diagnosis of CRS to analyze the expression of IL-4, IL-5, IL-10, IL-17 and IL- 33. The analysis was also performed in a group with CRS without exposure to cotton and control without CRS. Results: All individuals exposed to cotton with symptoms suggestive of CRS had a histological pattern with increased expression of IL-4, IL-5, IL-10, IL-17 and IL-33. Conclusions: This study confirms the close relationship between exposure to cotton in the workplace and the appearance of an inflammatory response with increased expression of interleukins studied. The possible institution of therapies / drugs that inhibit the expression of these cytokines could help in the reduction of the inflammatory process present in CRS and in the onset of the disease

A doença infecciosa que causa o maior número de mortes no mundo é a tuberculose, causada pelo bacilo Mycobacterium tuberculosis. Um dos fatores de risco que aumenta três vezes o desenvolvimento de tuberculose é a diabetes, sendo a obesidade associada com predisposição à diabetes. A obesidade gera inflamação de baixo grau que agrava a progressão de doenças crônicas. Estudos que avaliaram a associação da obesidade com tuberculose são controversos, e o tema merece maior investigação. No presente estudo, usamos um modelo experimental para determinar a interface da obesidade e da tuberculose. Camundongos C57BL/6 foram alimentados com dieta hiperlipídica (HFD - High Fat Diet) durante 60 dias, quando foram infectados com M. tuberculosis (HFD/Mtb) por via intra-traqueal. Como controles experimentais, animais foram alimentados com dieta padrão (LFD - Low Fat Diet) e infectados (LFD/Mtb). Paralelamente, um grupo recebeu HFD e outro LFD, e seguiram sem infecção. Após 30 dias de infecção, totalizando 90 dias de dieta, os diferentes grupos foram avaliados. Os animais obesos e infectados (HFD/Mtb) apresentaram aumento do peso corporal e do peso dos tecidos adiposos, aumento da expressão gênica de IL-1? no tecido adiposo, intolerância à glicose, deficiência na produção de insulina e aumento dos níveis séricos de IFN-? comparados aos animais LFD/Mtb. Além disso, o grupo HFD/Mtb foi mais suscetível e apresentou maior inflamação pulmonar comparado ao grupo LFD/Mtb. A inflamação foi caracterizada por aumento na expressão gênica para IL-17, IFN-?, TNF, IL-1?, IL-1?, NLRP3, caspase-1, IL-18, IL-6, aumento de células CD4+ produtoras de IFN-? e/ou IL-17 nos pulmões, e foi também acompanhada por aumento de células CD8+ e células CD4+Foxp3+ quando comparado ao grupo LFD/Mtb. Como NLRP3 é uma molécula chave na metainflamação induzida pela obesidade, mas seu papel ainda não está bem definido na tuberculose, animais deficientes de NLRP3 receberam HFD e foram infectados (NLRP3-/- HFD/Mtb). Esse grupo NLRP3-/- HFD/Mtb foi mais resistente e exibiu redução da inflamação pulmonar comparado ao grupo WT (Wild Type) HFD/Mtb. Sabendo que a obesidade está associada à disbiose e que produtos bacterianos derivados da dieta alimentar ou da microbiota podem estimular a liberação de IL-1? pela ativação de NLRP3, avaliamos o papel da microbiota na comorbidade obesidade e tuberculose. Encontramos disbiose intestinal, caracterizada por aumento do Filo Firmicutes e redução dos Filos Bacteroidetes e Proteobacteria, além do aumento de butirato e redução de acetato e propionato nos intestinos do grupo HFD/Mtb comparado ao grupo LFD/Mtb. O aumento na expressão de claudina-2 sugere alteração na permeabilidade intestinal e possível translocação bacteriana, caracterizada pela disbiose nos pulmões, nos quais foi detectado aumento de Firmicutes, Bacteroidetes e Actinobacteria, e redução de Proteobacteria no grupo HFD/Mtb. Em conclusão, a obesidade aumenta a magnitude da inflamação pulmonar e a suscetibilidade à infecção por M. tuberculosis por um mecanismo dependente de NLRP3. Ambos, aumento da suscetibilidade à infecção e da inflamação pulmonar estão associadas com disbiose intestinal e pulmonar, e aumento da permeabilidade intestinal. / The infectious disease that causes the largest number of deaths in the word is tuberculosis, caused by Mycobacterium tuberculosis bacilli. One of the risk factors that increases the devolpment of tuberculosis three times is diabetes. Obesity generates lowgrade inflammation that magnify the progression of chronic disease. Studies that have evaluated the association between obesity and tuberculosis are controversial, and the issue requires further investigation. In this study, we used an experimental model to determine the interface between obesity and tuberculosis. C57BL/6 mice were fed a highfat diet (HFD) for 60 days and infected by M. tuberculosis (HFD/Mtb) via intratracheal. As experimental control, animals were fed a light-fat diet (LFD) and were infected (LFD/Mtb). In parallel, one group was fed with HFD and another LFD, and they remained without infection. After 30 days of diet completing 90 days of feeding, the different groups were evaluated. Obese and infected animals (HFD/Mtb) showed increased body mass and adipose tissue weight, increased of IL-1? gene expression in adipose tissue, glucose intolerant, impaired insulin production and increased of serum levels of IFN-? compared to LFD/Mtb animals. In addition to, HFD/Mtb animals were more susceptible and exhibited higher lung inflammation compared to LFD/Mtb animals. The inflammation was characterized by increased of IL-17, IFN-?, TNF, IL-1?, IL-1?, NLRP3, caspase-1, IL-18, IL-6 gene expression and increase of IFN-? and/ or IL-17- producing CD4+ cells in the lungs, and was also accompanied by increased CD8+ and CD4+Foxp3+ cells compared to the LFD/Mtb group. As NLRP3 is a key molecule in obesity-induced meta-inflammation, but its role is still not well defined in tuberculosis, NLRP3 deficient animals fed with HFD and were infected (NLRP3-/- HFD/Mtb). This NLRP3-/- HFD/Mtb group was more resistant and exhibited reduction of lung inflammation compared to the WT (Wild Type) HFD/ Mtb group. Considerate that obesity-associated dysbiosis and that bacterial products derived from diet or microbiota can stimulate the release of IL-1? by the activation of NLRP3, we evaluated the microbiota role in obesity and tuberculosis comorbidity. We found intestinal dysbiosis characterized by increased Firmicutes phylum and reduction of Bacteroidetes and Proteobacteria phylum, as well as increased butyrate and diminished acetate and propionate in the intestine of the HFD/Mtb group compared to the LFD/Mtb group. An increase of claudin-2 expression suggests an alteration in intestinal permeability and a possible bacterial translocation characterized by dysbiosis in the lungs, with increased of Firmicutes, Bacteroidetes and Actinobacteria and diminished of Proteobacteria in the HFD/Mtb group. In conclusion, obesity increases the magnitude of pulmonary inflammation and susceptibility to M. tuberculosis infection by an NLRP3-depedent mechanism. Both increased susceptibility to infection and pulmonary inflammation are associated with intestinal and pulmonary dysbiosis, and increased intestinal permeability.

Dermatofitoses são infecções fúngicas de natureza crônica cujo principal agente etiológico é Trichophyton rubrum. Apesar de sua alta ocorrência mundial, pouco se sabe sobre os mecanismos imunológicos envolvidos nestas infecções. Neste trabalho investigamos a participação de duas classes de receptores de imunidade inata (NLRs e CLRs) na resposta a T.rubrum e avaliamos o perfil proteômico de macrófagos quando estimulados com o fungo. Observamos que T.rubrum foi capaz de induzir a produção de IL-1β dependente do inflamassomo NLRP3 e destacamos o papel da sinalização de IL-1 na modulação da resposta de IL-17. Determinamos os CLRs dectina-1 e dectina-2 como receptores essenciais na produção de citocinas inflamatórias e para o controle da infecção experimental. Curiosamente, a IL-17 e os linfócitos T e B foram dispensáveis para a eliminação do fungo. Também identificamos a proteína CLEC1A como uma novo receptor para fungos, envolvido no reconhecimento de glicolipídeos de T.rubrum. Por fim, a análise proteômica de macrofagos revelou a vimentina e a plastina-2 como duas proteínas potencialmente envolvidas na relação patógeno-hospedeiro. / Dermatophytosis are chronic fungal infections whose main causative agent is Trichophyton rubrum. Despite its high incidence worldwide, the immunological mechanisms underlying these infections remain largely unknown. Here we investigated the involvement of two classes of innate immune receptors (NLRs and CLRs) in the reponse to T.rubrum and performed a proteomic profiling of macrophages upon T.rubrum stimulation. We observed that T.rubrum was able to drive NLRP3 inflammasome-derived IL-1β production and highlighted IL-1 signaling as an important component in the shaping of the IL-17 response. We defined the CLRs dectin-1 and dectin-2 as key receptors for the induction of inflammatory cytokines and for the infection control in the in vivo settings. Curiously, IL-17 cytokines and T and B lymphocytes were dispensable for fungal clearance. In addition, we uncovered CLEC1A as a new receptor in fungal sensing, involved in the recognition of T.rubrum glycolipids. Finally, the proteomic analysis revealed Vimentin and Plastin-2 as two proteins potentially involved in the host-pathogen interaction.

A doença infecciosa que causa o maior número de mortes no mundo é a tuberculose, causada pelo bacilo Mycobacterium tuberculosis. Um dos fatores de risco que aumenta três vezes o desenvolvimento de tuberculose é a diabetes, sendo a obesidade associada com predisposição à diabetes. A obesidade gera inflamação de baixo grau que agrava a progressão de doenças crônicas. Estudos que avaliaram a associação da obesidade com tuberculose são controversos, e o tema merece maior investigação. No presente estudo, usamos um modelo experimental para determinar a interface da obesidade e da tuberculose. Camundongos C57BL/6 foram alimentados com dieta hiperlipídica (HFD - High Fat Diet) durante 60 dias, quando foram infectados com M. tuberculosis (HFD/Mtb) por via intra-traqueal. Como controles experimentais, animais foram alimentados com dieta padrão (LFD - Low Fat Diet) e infectados (LFD/Mtb). Paralelamente, um grupo recebeu HFD e outro LFD, e seguiram sem infecção. Após 30 dias de infecção, totalizando 90 dias de dieta, os diferentes grupos foram avaliados. Os animais obesos e infectados (HFD/Mtb) apresentaram aumento do peso corporal e do peso dos tecidos adiposos, aumento da expressão gênica de IL-1? no tecido adiposo, intolerância à glicose, deficiência na produção de insulina e aumento dos níveis séricos de IFN-? comparados aos animais LFD/Mtb. Além disso, o grupo HFD/Mtb foi mais suscetível e apresentou maior inflamação pulmonar comparado ao grupo LFD/Mtb. A inflamação foi caracterizada por aumento na expressão gênica para IL-17, IFN-?, TNF, IL-1?, IL-1?, NLRP3, caspase-1, IL-18, IL-6, aumento de células CD4+ produtoras de IFN-? e/ou IL-17 nos pulmões, e foi também acompanhada por aumento de células CD8+ e células CD4+Foxp3+ quando comparado ao grupo LFD/Mtb. Como NLRP3 é uma molécula chave na metainflamação induzida pela obesidade, mas seu papel ainda não está bem definido na tuberculose, animais deficientes de NLRP3 receberam HFD e foram infectados (NLRP3-/- HFD/Mtb). Esse grupo NLRP3-/- HFD/Mtb foi mais resistente e exibiu redução da inflamação pulmonar comparado ao grupo WT (Wild Type) HFD/Mtb. Sabendo que a obesidade está associada à disbiose e que produtos bacterianos derivados da dieta alimentar ou da microbiota podem estimular a liberação de IL-1? pela ativação de NLRP3, avaliamos o papel da microbiota na comorbidade obesidade e tuberculose. Encontramos disbiose intestinal, caracterizada por aumento do Filo Firmicutes e redução dos Filos Bacteroidetes e Proteobacteria, além do aumento de butirato e redução de acetato e propionato nos intestinos do grupo HFD/Mtb comparado ao grupo LFD/Mtb. O aumento na expressão de claudina-2 sugere alteração na permeabilidade intestinal e possível translocação bacteriana, caracterizada pela disbiose nos pulmões, nos quais foi detectado aumento de Firmicutes, Bacteroidetes e Actinobacteria, e redução de Proteobacteria no grupo HFD/Mtb. Em conclusão, a obesidade aumenta a magnitude da inflamação pulmonar e a suscetibilidade à infecção por M. tuberculosis por um mecanismo dependente de NLRP3. Ambos, aumento da suscetibilidade à infecção e da inflamação pulmonar estão associadas com disbiose intestinal e pulmonar, e aumento da permeabilidade intestinal. / The infectious disease that causes the largest number of deaths in the word is tuberculosis, caused by Mycobacterium tuberculosis bacilli. One of the risk factors that increases the devolpment of tuberculosis three times is diabetes. Obesity generates lowgrade inflammation that magnify the progression of chronic disease. Studies that have evaluated the association between obesity and tuberculosis are controversial, and the issue requires further investigation. In this study, we used an experimental model to determine the interface between obesity and tuberculosis. C57BL/6 mice were fed a highfat diet (HFD) for 60 days and infected by M. tuberculosis (HFD/Mtb) via intratracheal. As experimental control, animals were fed a light-fat diet (LFD) and were infected (LFD/Mtb). In parallel, one group was fed with HFD and another LFD, and they remained without infection. After 30 days of diet completing 90 days of feeding, the different groups were evaluated. Obese and infected animals (HFD/Mtb) showed increased body mass and adipose tissue weight, increased of IL-1? gene expression in adipose tissue, glucose intolerant, impaired insulin production and increased of serum levels of IFN-? compared to LFD/Mtb animals. In addition to, HFD/Mtb animals were more susceptible and exhibited higher lung inflammation compared to LFD/Mtb animals. The inflammation was characterized by increased of IL-17, IFN-?, TNF, IL-1?, IL-1?, NLRP3, caspase-1, IL-18, IL-6 gene expression and increase of IFN-? and/ or IL-17- producing CD4+ cells in the lungs, and was also accompanied by increased CD8+ and CD4+Foxp3+ cells compared to the LFD/Mtb group. As NLRP3 is a key molecule in obesity-induced meta-inflammation, but its role is still not well defined in tuberculosis, NLRP3 deficient animals fed with HFD and were infected (NLRP3-/- HFD/Mtb). This NLRP3-/- HFD/Mtb group was more resistant and exhibited reduction of lung inflammation compared to the WT (Wild Type) HFD/ Mtb group. Considerate that obesity-associated dysbiosis and that bacterial products derived from diet or microbiota can stimulate the release of IL-1? by the activation of NLRP3, we evaluated the microbiota role in obesity and tuberculosis comorbidity. We found intestinal dysbiosis characterized by increased Firmicutes phylum and reduction of Bacteroidetes and Proteobacteria phylum, as well as increased butyrate and diminished acetate and propionate in the intestine of the HFD/Mtb group compared to the LFD/Mtb group. An increase of claudin-2 expression suggests an alteration in intestinal permeability and a possible bacterial translocation characterized by dysbiosis in the lungs, with increased of Firmicutes, Bacteroidetes and Actinobacteria and diminished of Proteobacteria in the HFD/Mtb group. In conclusion, obesity increases the magnitude of pulmonary inflammation and susceptibility to M. tuberculosis infection by an NLRP3-depedent mechanism. Both increased susceptibility to infection and pulmonary inflammation are associated with intestinal and pulmonary dysbiosis, and increased intestinal permeability.

Dermatofitoses são infecções fúngicas de natureza crônica cujo principal agente etiológico é Trichophyton rubrum. Apesar de sua alta ocorrência mundial, pouco se sabe sobre os mecanismos imunológicos envolvidos nestas infecções. Neste trabalho investigamos a participação de duas classes de receptores de imunidade inata (NLRs e CLRs) na resposta a T.rubrum e avaliamos o perfil proteômico de macrófagos quando estimulados com o fungo. Observamos que T.rubrum foi capaz de induzir a produção de IL-1β dependente do inflamassomo NLRP3 e destacamos o papel da sinalização de IL-1 na modulação da resposta de IL-17. Determinamos os CLRs dectina-1 e dectina-2 como receptores essenciais na produção de citocinas inflamatórias e para o controle da infecção experimental. Curiosamente, a IL-17 e os linfócitos T e B foram dispensáveis para a eliminação do fungo. Também identificamos a proteína CLEC1A como uma novo receptor para fungos, envolvido no reconhecimento de glicolipídeos de T.rubrum. Por fim, a análise proteômica de macrofagos revelou a vimentina e a plastina-2 como duas proteínas potencialmente envolvidas na relação patógeno-hospedeiro. / Dermatophytosis are chronic fungal infections whose main causative agent is Trichophyton rubrum. Despite its high incidence worldwide, the immunological mechanisms underlying these infections remain largely unknown. Here we investigated the involvement of two classes of innate immune receptors (NLRs and CLRs) in the reponse to T.rubrum and performed a proteomic profiling of macrophages upon T.rubrum stimulation. We observed that T.rubrum was able to drive NLRP3 inflammasome-derived IL-1β production and highlighted IL-1 signaling as an important component in the shaping of the IL-17 response. We defined the CLRs dectin-1 and dectin-2 as key receptors for the induction of inflammatory cytokines and for the infection control in the in vivo settings. Curiously, IL-17 cytokines and T and B lymphocytes were dispensable for fungal clearance. In addition, we uncovered CLEC1A as a new receptor in fungal sensing, involved in the recognition of T.rubrum glycolipids. Finally, the proteomic analysis revealed Vimentin and Plastin-2 as two proteins potentially involved in the host-pathogen interaction.

La tuberculose est encore aujourd’hui un problème de santé majeur et l’augmentation des cas de tuberculoses résistantes au niveau mondial, associé au dépistage et diagnostic insuffisants, suggère une éradication totale encore lointaine. La compréhension des relations hôte-pathogène est essentielle pour permettre d’établir de nouvelles stratégies thérapeutiques. Ces travaux de thèse ont mis en exergue la contribution limitée de la voie de signalisation IL-36, cytokine de la famille de l’IL-1, au cours de l’infection mycobactérienne. Ces données permettent d’envisager sérieusement l’IL-36 en tant que cible thérapeutique pour le psoriasis sans risquer la réactivation de tuberculose latente chez les patients. De plus, nous avons également démontré le rôle différentiel de la voie de signalisation TNF au sein de populations cellulaires spécifiques lors de l’infection par M. tuberculosis, et nos résultats apportent des connaissances solides pour envisager des stratégies immuno-modulatoires qui pourraient constituer l’avenir des traitements antituberculeux. D’autre part, nous avons caractérisé un modèle murin humanisé pour une étude facilitée des anticorps anti-TNF humains actuels. L’utilisation de ce modèle pourrait permettre, à termes, d’identifier et de valider de nouveaux candidats d’anticorps anti-TNF de deuxième génération. Enfin, nous avons montré que des anticorps neutralisants l’IL-17 ne perturbent pas la réponse immunitaire à la tuberculose, contrairement aux anticorps anti-TNF, et que l’absence de l’IL-17 n’est pas compensée par l’IL-22 puisque des animaux déficients pour ces deux voies de signalisation sont capables de contrôler l’infection. / Tuberculosis remains a major health problem in the world nowadays. The increasing incidence of resistant tuberculosis is associated with a poor diagnosis, reflecting important difficulties for total eradication. Understand host-pathogen interactions is crucial to establish new therapeutic strategies. This work first shows the limited contribution of IL-36 pathway during mycobacterial infection. These results suggest that IL-36 could be targeted for the treatment of psoriasis without a high risk of tuberculosis reactivation. We then demonstrate the differential role of TNF pathway among myeloid or lymphoid cells during M. tuberculosis infection, and our data support the development of immunomodulatory strategies to boost host immune response, thus helping to clear the infection. Moreover, we characterize a humanized murine model allowing the study of new anti-TNF candidates in the context of M. tuberculosis infection. Finally, we show that antibodies targeting IL-17 does not dampen host control of M. tuberculosis infection, unlike anti-TNF, and that IL-22 does not compensate absence of IL-17 for this control.

Diese Arbeit beschreibt Ergebnisse einer in-vitro Untersuchung der Antipsychotika Chlorpromazin, Haloperidol, Clozapin, N-Desmethylclozapin und Quetiapin bezüglich ihrer Wirkung auf die Zytokinproduktion. Dafür wurde Vollblut von gesunden Probandinnen invitro mit dem Immunmodulator Toxic-Shock-Syndrome-Toxin-1 (TSST-1) stimuliert. Dabei wurden die Konzentrationen der Zytokine Interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-17 und Tumornekrosefaktor-α (TNF-α) im unstimulierten Blut und im stimulierten Blut, jeweils mit und ohne Zusatz der Antipsychotika gemessen. Es zeigte sich, dass TSST-1 eine signifikante Stimulation der Produktion aller getesteten Zytokine bewirkte und dass es über diese Stimulation mit TSST-1 hinaus zu einer Erhöhung von IL-17 unter allen getesteten Antipsychotika kam. Aufgrund dieser Ergebnisse ist es denkbar, dass Antipsychotika, in Ergänzung zu ihrer Wirkung an Dopaminrezeptoren, auch über diese immunologische Eigenschaft Wirkungen und Nebenwirkungen entfalten können. Weiterhin könnte die IL-17-Produktion ein Biomarker in der Behandlung mit Antipsychotika sein, der wiederum zur individuellen Vorhersage von Wirkungen und Nebenwirkungen beitragen könnte.

The human pathogen Trypanosoma cruzi is an intracellular parasite and the etiological agent of Chagas disease. Protective immune responses to T. cruzi are highly dependent on T helper 1 and CD8+ T cells which produce interferon-gamma. A deficiency in these responses has severe consequences on the ability to control infection. Our investigation into the role of the Th1 transcription factor, T-bet, during murine T. cruzi infection revealed that T-bet is required for resistance. Contrary to our expectations, T-bet was not required for the development of Th1 immunity during infection, as T-bet-deficient mice still developed interferon-gamma-producing T cells. However, T-bet was required to suppress the differentiation of Th17 cells and for the expansion of T. cruzi-specific CD8+ T cells. We first sought to determine the cause of reduced numbers of T. cruzi-specific CD8+ T cells in infected T-bet-deficient mice. First, we found that impaired migration or survival did not contribute to the low number of T. cruzi-specific CD8+ T cells. Secondly, we determined that reduced numbers of CD8+ T cells was not secondary to a defect in antigen-presenting cell activation or priming of CD8+ T cells. A recapitulation of defective expansion in mice with normal T-bet-expressing antigen-presenting cells demonstrated that T-bet expression in T cells was required. Thus, we determined that T-bet regulates the expansion of antigen-specific CD8+ T cells during T. cruzi infection in a T cell-intrinsic manner. Although it was evident T-bet had an integral role in suppressing the development of Th17 cells in response to infection with T. cruzi, several issues remained unclear. The first was the apparent lack of a negative regulatory effect of IFN-g/IFN-g-signaling on Th17 cells, which contradicted published reports. To clarify the role of IFN-g, we investigated the effect of IFN-g- or Stat-1-deficiency during T. cruzi infection. Surprisingly, IFN-g did not have a major role in up-regulating T-bet or for suppressing the development of Th17 responses, whereas Stat-1 was necessary for both. This was unexpected as Stat-1 is an IFN-g-inducible transcription factor, and its activation leads to T-bet induction. Thus, the T-bet-mediated inhibition of Th17 responses during T. cruzi infection is dependent on Stat-1, but not IFN-g. The final aim of this project was to identify the cytokines that negatively regulate Th17 differentiation in response to T. cruzi. We focused on the IL-12-family cytokines, IL-12 and IL-27, which are known to regulate T cell responses. Indeed, IL-12-deficient mice infected with T. cruzi developed a significant increase in Th17 cells similar to that observed in T-bet-deficient mice. Surprisingly, and in contrast to published results in other models, IL-27-deficient mice did not exhibit an increase in Th17 development. Our results demonstrate that IL-12, but not IL-27, is necessary for optimal T-bet expression and regulation of Th17 responses during T. cruzi infection.

No description available.

La neuropiline-1 (Nrp-1) est une protéine transmembranaire agissant comme récepteur des sémaphorines de classe 3 (Sema3) et du facteur de croissance de l'endothélium vasculaire (VEGF). En plus de son rôle crucial dans le développement des systèmes nerveux et cardiovasculaires, Nrp-1 est impliquée dans des processus physiopathologiques impliquant certains de ses ligands classiques (Sema3 et VEGF) ou récemment caractérisés (TGF-β1 et PDGF) dans les tissus adultes. Dans le système immunitaire, Nrp-1 participe aux interactions entre les lymphocytes T et les cellules dendritiques, transmet les effets immunorégulateurs de Sema3A sur les lymphocytes T, et est impliqué dans le mécanisme suppresseur des lymphocytes T régulateurs (Treg) Foxp3+. Cependant, l'expression de Nrp-1 dans les lymphocytes T non-Treg humains et murins n'a été que peu étudiée. L'objectif de ce projet était de caractériser les populations de lymphocytes T Nrp-1+ non-Treg chez la souris, d'analyser leurs fonctions, d'identifier les mécanismes conduisant à l'expression de Nrp-1 dans ces cellules, et de comprendre le rôle joué par Nrp-1 dans les réponses immunitaires T. Mon travail s'est d'une part intéressé à une population de lymphocytes T non-conventionnels appelés lymphocytes « invariant natural killer T » (iNKT). Les lymphocytes iNKT sont des lymphocytes Tαβ dérivés du thymus aux propriétés immunomodulatrices reposant sur la sécrétion rapide de cytokines TH1 et TH2 après engagement de leur TCR semi-invariant par des complexes CD1d/glycolipide. Un sous-type distinct de cellules iNKT, dont l'origine et l'homéostasie sont encore mal connues, produit la cytokine pro-inflammatoire IL-17. Dans ce travail, j'ai montré que les lymphocytes iNKT émigrés thymiques récents sont identifiés spécifiquement par l'expression de Nrp-1. Les lymphocytes iNKT producteurs d'IL-17 expriment Nrp-1 et dépendent de l'export thymique. D'autre part, Nrp-1 est exprimé par les thymocytes immatures en division et certains lymphocytes Tαβ conventionnels mémoires en prolifération homéostatique rapide. In vitro, l'activation des lymphocytes T par le TCR induit l'expression de Nrp-1 de manière dépendante de la voie de signalisation Ca2+/calcineurine/NFAT. L'expression de Nrp-1 dans les lymphocytes T activés les sensibilise aux effets régulateurs de Sema3A et TGF-β1. En conclusion, ces résultats apportent de nouvelles données concernant l'expression et la fonction de Nrp-1 dans le système immunitaire. Plus généralement, cette étude permet d'envisager des stratégies thérapeutiques ciblant les processus dépendants de Nrp-1 dans les pathologies du système immunitaire et du système nerveux ou les cancers.