No description available.

No description available.

O câncer de ovário é uma importante causa de mortalidade. O subtipo seroso de alto grau é o mais frequente e caracteriza-se por comportamento agressivo, com crescimento rápido e metástase precoce. A falta de ferramentas para diagnóstico em estádios iniciais e a insuficiência de resposta à quimioterapia convencional são dois principais obstáculos para o manejo do câncer seroso de ovário. A detecção precoce neste tumor é complicada por sintomas inespecíficos e ausência de biomarcadores confiáveis. Além disso, o desenvolvimento de resistência à quimioterapia é um desafio para o tratamento, que é geralmente baseado na combinação de platina e paclitaxel. A influência do microambiente tumoral na resposta terapêutica ainda é pouco conhecida. No entanto, há evidências crescentes de que a resposta imunológica pré-existente pode estar relacionada com a variação da sensibilidade à quimioterapia. O microambiente imunorreativo foi associado à melhor prognóstico no câncer do ovário seroso de alto grau em recente estudo canadense. Proteínas da família de Transdutores de Sinal e Ativadores da Transcrição (STATs) participam da regulação de citocinas e são determinantes nas respostas imunes no microambiente tumoral, podendo promover ou inibir o crescimento tumoral. Dados recentes mostram que a expressão elevada de um dos reguladores de STAT, STAT1 atua na tumorigênese do câncer de ovário, facilitando a resposta imune e, potencialmente, alterando a resposta à quimioterapia. Para avaliar o papel da expressão de STAT1 como biomarcador preditivo em 65 pacientes brasileiras com câncer seroso de ovário, examinamos os níveis de STAT1 por imunoistoquímica, e analisamos se houve correlação entre expressão dessa proteína e resposta clínica. Alta expressão de STAT1 foi significativamente associada maior intervalo livre de doença (P=0,0256) e maior sobrevida global (P=0,0193). Estes achados da coorte brasileira, com tempo de seguimento maior que cinco anos, confirmam a associação entre alta expressão de STAT1 e melhor resposta à quimioterapia, e fornecem validação adicional desta proteína como um biomarcador preditivo. Além disso, estes resultados chamam atenção para a possibilidade de utilizar a via de STAT1 para o desenvolvimento de novos medicamentos imunomoduladores, que poderiam melhorar a resposta ao tratamento / Ovarian cancer is a major cause of mortality worldwide. The most frequent subtype is high grade serous, which is characterized by aggressive behavior with rapid growth and early metastasis. Lack of early diagnostic tools and failure of response to conventional chemotherapies are two major impediments to serous ovarian cancer management. Early detection in initial stages is complicated by non-specific symptoms and lack of reliable biomarkers. In addition, development of chemotherapy resistance is a challenge for treatment, which is generally based on combination of platinum and paclitaxel. The influence of the microenvironment of the tumor on therapeutic response is still unknown. However, there is increasing evidence that a pre-existing immunological response may be related to variation in chemotherapy sensitivity. The immunoreactive microenvironment has been shown to be associated with better prognosis in high grade serous ovarian cancer in a recent Canadian study. The Signal Transducer and Activator of Transcription (STAT) proteins regulate cytokines and are central in determining whether immune responses in the tumor microenvironment promote or inhibit cancer. Recent data show that high expression of one of the STAT regulators, STAT1, operates in ovarian cancer tumorigenesis, facilitating immune response and potentially altering response to chemotherapy. To evaluate the role of STAT1 expression as a predictive biomarker in 65 Brazilian serous ovarian cancer patients, we examined STAT1 levels by immunohistochemistry to determine if there was correlation between expression of this protein and clinical response. High expression of STAT1 was significantly associated with both improved disease-free survival (P=0,0256) and overall survival (P=0,0193). These findings from a Brazilian cohort after more than five years of follow up confirm the association of high STAT1 expression with better response to chemotherapy, and provide additional validation of this protein as a predictive biomarker. Moreover these results draw attention to the possibility of utilizing the STAT1 pathway for the development new immunomodulator drugs, that could enhance response to treatment

O câncer de ovário é uma importante causa de mortalidade. O subtipo seroso de alto grau é o mais frequente e caracteriza-se por comportamento agressivo, com crescimento rápido e metástase precoce. A falta de ferramentas para diagnóstico em estádios iniciais e a insuficiência de resposta à quimioterapia convencional são dois principais obstáculos para o manejo do câncer seroso de ovário. A detecção precoce neste tumor é complicada por sintomas inespecíficos e ausência de biomarcadores confiáveis. Além disso, o desenvolvimento de resistência à quimioterapia é um desafio para o tratamento, que é geralmente baseado na combinação de platina e paclitaxel. A influência do microambiente tumoral na resposta terapêutica ainda é pouco conhecida. No entanto, há evidências crescentes de que a resposta imunológica pré-existente pode estar relacionada com a variação da sensibilidade à quimioterapia. O microambiente imunorreativo foi associado à melhor prognóstico no câncer do ovário seroso de alto grau em recente estudo canadense. Proteínas da família de Transdutores de Sinal e Ativadores da Transcrição (STATs) participam da regulação de citocinas e são determinantes nas respostas imunes no microambiente tumoral, podendo promover ou inibir o crescimento tumoral. Dados recentes mostram que a expressão elevada de um dos reguladores de STAT, STAT1 atua na tumorigênese do câncer de ovário, facilitando a resposta imune e, potencialmente, alterando a resposta à quimioterapia. Para avaliar o papel da expressão de STAT1 como biomarcador preditivo em 65 pacientes brasileiras com câncer seroso de ovário, examinamos os níveis de STAT1 por imunoistoquímica, e analisamos se houve correlação entre expressão dessa proteína e resposta clínica. Alta expressão de STAT1 foi significativamente associada maior intervalo livre de doença (P=0,0256) e maior sobrevida global (P=0,0193). Estes achados da coorte brasileira, com tempo de seguimento maior que cinco anos, confirmam a associação entre alta expressão de STAT1 e melhor resposta à quimioterapia, e fornecem validação adicional desta proteína como um biomarcador preditivo. Além disso, estes resultados chamam atenção para a possibilidade de utilizar a via de STAT1 para o desenvolvimento de novos medicamentos imunomoduladores, que poderiam melhorar a resposta ao tratamento / Ovarian cancer is a major cause of mortality worldwide. The most frequent subtype is high grade serous, which is characterized by aggressive behavior with rapid growth and early metastasis. Lack of early diagnostic tools and failure of response to conventional chemotherapies are two major impediments to serous ovarian cancer management. Early detection in initial stages is complicated by non-specific symptoms and lack of reliable biomarkers. In addition, development of chemotherapy resistance is a challenge for treatment, which is generally based on combination of platinum and paclitaxel. The influence of the microenvironment of the tumor on therapeutic response is still unknown. However, there is increasing evidence that a pre-existing immunological response may be related to variation in chemotherapy sensitivity. The immunoreactive microenvironment has been shown to be associated with better prognosis in high grade serous ovarian cancer in a recent Canadian study. The Signal Transducer and Activator of Transcription (STAT) proteins regulate cytokines and are central in determining whether immune responses in the tumor microenvironment promote or inhibit cancer. Recent data show that high expression of one of the STAT regulators, STAT1, operates in ovarian cancer tumorigenesis, facilitating immune response and potentially altering response to chemotherapy. To evaluate the role of STAT1 expression as a predictive biomarker in 65 Brazilian serous ovarian cancer patients, we examined STAT1 levels by immunohistochemistry to determine if there was correlation between expression of this protein and clinical response. High expression of STAT1 was significantly associated with both improved disease-free survival (P=0,0256) and overall survival (P=0,0193). These findings from a Brazilian cohort after more than five years of follow up confirm the association of high STAT1 expression with better response to chemotherapy, and provide additional validation of this protein as a predictive biomarker. Moreover these results draw attention to the possibility of utilizing the STAT1 pathway for the development new immunomodulator drugs, that could enhance response to treatment

Mon projet de thèse a consisté en l’identification et la caractérisation moléculaire et immunologique de patients présentant une susceptibilité accrue aux infections fongiques par Candida sp. dans le syndrome Mendélien de candidose cutanéo-muqueuse chronique (CCMC).La CCMC est caractérisée par des infections persistantes ou récurrentes de la peau, des ongles et des muqueuses par les champignons Candida, principalement C. albicans. Elle est fréquemment associée à d’autres infections opportunistes dans certaines immunodéficiences primaires ou acquises, ou bien elle peut être associée à un tableau auto-immun. La CCMC peut finalement être isolée (CCMCi) sans autre tableau clinique sévère: la plupart des cas rapportés sont sporadiques, mais il existe également des cas familiaux avec une hérédité mendélienne autosomique principalement dominante (AD) ou plus rarement récessive (AR).Basés sur les données de la littérature, qui démontrent un rôle majeur de l’immunité dépendante des IL-17s dans la résistance aux infections mucocutanées vis-à-vis de C. albicans et nos résultats récents, qui démontrent un défaut de cette immunité dans certaines immunodéficiences primaires associées à une CCMC [les syndromes AD-HIES et AR APS-1, ainsi que chez les patients déficients en CARD9, nous avons émis l’hypothèse que parmi les patients atteints de CCMCi, certains pourraient présenter un défaut génétique affectant spécifiquement l’immunité IL-17-dépendante. Au début de ma thèse, j’ai participé à l’identification des deux premières étiologies génétiques de la CCMCi : le défaut autosomique récessif (AR) complet en IL-17RA et autosomique dominant (AD) en IL-17F. Plus récemment, j’ai identifié la troisième et la plus fréquente étiologie génétique de la CCMC par l’identification de mutations gain de fonction dans le gène STAT1 suite à une approche explorant l’ensemble du génome (séquençage de l’ensemble des exons). Ces mutations engendrent une « hyper-réponse » aux interférons de type I et II et à l’IL-27 qui inhibent la différentiation des lymphocytes T sécréteurs d’IL-17, impliqués dans l’immunité mucocutanée vis-à-vis de C. albicans chez l’homme.En conclusion, nous avons identifié, en 2011, des trois premières étiologies génétiques de la CCMCi, avec les défauts AR en IL-17RA, AD en IL-17F et des mutations gain-de-fonction de STAT1, toutes associées à un défaut de l’immunité dépendante de l’IL-17. Des mutations gain-de-fonction de STAT1 représentent à ce jour la cause génétique la plus fréquente de la CCMCi avec au total 94 patients rapportés dans la littérature depuis 2011. Nous avons ainsi démontré que la CCMCi est une immunodéficience primaire, associée à un défaut de l’immunité réalisée par les IL-17s. Ces travaux ont des implications majeures dans le domaine immunologique avec la description et la caractérisation des mécanismes biologiques impliqués dans l’immunité protectrice spécifique de C. albicans et une meilleure compréhension des mécanismes physiopathologiques associés à une susceptibilité accrue aux infections fongiques, dans des conditions naturelles d’infection ; et dans le domaine médical, avec la possibilité de diagnostics moléculaires, un conseil génétique en cas de diagnostic positif, une meilleure prise en charge des patients. / My project consists in the molecular and immunological identification and characterization of patients with increased susceptibility to fungal infections with Candida sp. suffering from the Mendelian syndrome of chronic mucocutaneous candidiasis (CMC).CMC is characterized by persistent or recurrent infections of the skin, nails and mucosae by Candida fungi, especially C. albicans. CMC is frequently associated with other opportunistic infections in some acquired or primary immunodeficiencies, or can be associated with autoimmune disorders. Finally, CMC may be present as an isolated form (chronic mucocutaneous candidiasis disease or CMCD) without any other severe infectious or autoimmune clinical manifestation: most reported cases are sporadic, but there are also familial cases with autosomal dominant (AD) or recessive (AR) Mendelian inheritance.Based the literature, which demonstrated a major role of IL-17 cytokines in mucocutaneous immunity with C. albicans, and our recent results, which show an impairment of IL-17 immunity in some primary immunodeficiencies associated with CMC (AD-HIES syndrome, AR APS-1, and CARD9-deficient patients), we hypothesized that among CMCD patients, some might have a genetic defect affecting specifically the IL-17-dependent immunity.At the beginning of my PhD, I participated in the identification of the first two genetic etiologies of CMCD: complete AR IL-17RA and partial AD IL-17F deficiencies. More recently, I identified the third and most common genetic etiology of CMCD by identifying gain of function mutations in the STAT1 gene following an approach exploring the whole genome (sequencing of all exons). These mutations are responsible for a "hyper-response" to type I and II interferons and IL-27, which inhibit the differentiation of IL-17-producing T cells. Impaired IL-17 immunity results in reduced mucocutaneous defenses against C. albicans in humans. In conclusion, we have identified in 2011, the first three genetic etiologies of CMCD with AR IL-17RA and AD IL-17F deficiencies and gain-of-function STAT1 mutations, all associated with an impaired IL-17-dependent immunity. Gain-of-function STAT1 mutations represent the most frequent genetic cause of CMCD with a total of 94 patients reported in the literature since 2011. We have shown that CMCD is a primary immunodeficiency associated with inborn errors of IL-17 immunity. This work has important implications in the field of immunology with the description and characterization of the biological mechanisms involved in protective immunity specific to C. albicans and a better understanding of the pathophysiological mechanisms associated with increased susceptibility to fungal infections in natural conditions of infection, and in the medical field, with the possibility of molecular diagnostics, genetic counseling for a positive diagnosis, and a better follow-up of the patients.

The signal transducer and activator of transcription 1 (STAT1) and 2 (STAT2) are primarily activated by interferons and play a central role in orchestrating responses to a variety of pathogens by activating the transcription of nuclear encoded genes that mediate antiviral, antigrowth and immune surveillance responses. In addition to their nuclear effects, we report that STAT1 and STAT2 inhibit the expression of mitochondrial encoded mRNAs by activating type I interferons (IFNβ) under basal conditions. STAT1-/- livers also exhibit elevated levels of nuclear encoded components of the electron transport chain (ETC). Treatment of wild-type mice with IFNβ inhibits both mitochondrial and nuclear transcription of the ETC components. The inhibition of mitochondrial encoded transcription by IFNβ is both STAT1 independent and dependent because it is also seen in STAT1-/- mice. This inhibitory action of IFNβ on mitochondrial transcription is mediated by a small pool of STAT1 and STAT2 residing within the mitochondria. This study would suggest a novel mechanism for STAT1 and STAT2, wherein they negatively regulate mitochondrial transcription and STAT1 coordinately regulates transcription of both mitochondrial and nuclear ETC components upon IFNβ stimulation. PGC1α has been described as the master regulator of mitochondrial biogenesis, and upon starvation its levels are elevated within the liver to increase mitochondrial biogenesis. The levels of PGC1α are increased in the STAT1-/- mice basally. However they are not increased further under starvation. Additionally, we report a novel phenotype of the STAT1-/- mice that suggests that they have a dysregulation of energy expenditure during starvation. We see that activation of hormone sensitive lipase which is the rate limiting step of lipolysis is attenuated in the adipose tissue of STAT1-/- mice and that there is less lipid accumulation in the livers of STAT1-/- compared to wild-type mice. The mechanism of STAT1’s role in energy regulation is not fully understood; however, this report would suggest that STAT1 does play a role within fasting homeostasis that is independent of IFNβ.

No description available.

Background: Azithromycin polarizes macrophages into an alternative phenotype and promotes a regulated immunity. Arginase is an important effector of these macrophages believed to play an essential role in decreasing injury and promoting repair. Hypothesis: Decreases in inflammation in response to Pseudomonas aeruginosa (PA) pneumonia achieved by polarizing macrophages to an alternative phenotype is dependent upon the production of arginase. Methods: Requirement of arginase was examined by pharmacological inhibition using S-(2-boronoethyl)- l-cysteine (BEC) or l-norvaline and by infecting arginase-1 conditional knock-out mice (Arg1flox/flox;Lyz2-cre (Arg1Δm)) with PA intratracheally. Arg1ΔM and control Arg1flox/flox mice were then dosed with azithromycin daily via oral gavage beginning four days prior to infection. Analysis of weight loss in addition to characterization of inflammatory cells and cytokine production via flow cytometry was performed. Macrophages were then stimulated with LPS and polarized with IL4/13, IFNγ, or azithromycin plus IFNγ. Western blot for signaling mediators, p65 translocation assay, and immunofluorescence were performed. Results: Myeloid arginase-1 deletion resulted in greater morbidity along with more severe inflammatory response compared to the Arg1flox/flox mice. Arg1Δm mice had greater numbers of neutrophils, macrophages, and lymphocytes in their airways and lymph nodes compared to the Arg1flox/flox mice. Conversely, global arginase inhibition resulted in greater weight loss along with greater neutrophil and macrophage infiltration compared to Arg1Δm mice. BEC and l-norvaline treated mice had higher numbers of lymphocytes in their lymph nodes with variable effects on airway lymphocyte counts. Azithromycin treatment comparably reduced the acute inflammatory responses in both Arg1Δm and Arg1flox/flox mice. To evaluate this mechanism, we show in vitro that azithromycin decreases NF-κB activation by preventing p65 nuclear translocation and by decreasing STAT1 activation in a concentration-dependent manner. These effects were reversed with IKKβ inhibition. Conclusions: Myeloid arginase is essential for control of inflammatory responses in PA pneumonia with potentially different effects of other cellular sources demonstrated with global arginase inhibition. Azithromycin reduces excessive inflammation even in the absence of arginase, potentially through a cross-inhibitory mechanism involving STAT1 and NF-κB pathways through IKKβ.

<p>All-trans retinoic acid (ATRA), a biologically active metabolite of vitamin A, is a powerful inducer of terminal differentiation and growth arrest of several myeloid cell lines <i>in vitro</i>. Although the efficacy of ATRA as an anti-cancer drug has been demonstrated by the successful treatment of acute promyelocytic leukemia (APL), knowledge concerning the molecular mechanisms directing ATRA-induced differentiation and cell cycle arrest of myeloid cells is lacking. Our results show, for the first time, that the complex regulation of cell cycle proteins and myeloid-specific transcription factors induced by ATRA relies on functional Stat1. We found that Stat1 is activated by both tyrosine-701 and serine-727 phosphorylation upon ATRA-induced differentiation of the human monoblastic cell line U-937. Expression of phosphorylation deficient mutants of Stat1 (Stat1Y701F or Stat1S727A) inhibited both ATRA-induced differentiation and cell cycle arrest of U-937 cells, pointing to a requirement of active Stat1 in these processes. </p><p>Detailed analysis of the molecular mechanism of ATRA-induced cell cycle arrest and differentiation showed that the onset of cell cycle arrest was associated with a decrease in c-Myc and cyclin E levels and upregulation of p27^Kip1 and p21^WAF1/CIP1. This was followed by a rapid fall in cyclin A and B and a coordinate dephosphorylation of the retinoblastoma protein (pRb). The inhibition of ATRA-induced cell-cycle arrest by constitutive expression of Stat1Y701F or Stat1S727A was associated with impaired regulation of these cyclins and p27^Kip1, positioning Stat1 activation upstream of these events. To further understand the process of ATRA-induced differentiation, the regulation of myeloid-specific transcription factors was investigated during ATRA-treatment. Notably, ATRA-induced upregulation of Stat2, ICSBP and C/EBP-ε was selectively impaired in sublines expressing Stat1Y701F or Stat1S727A, suggesting an important function of these factors downstream Stat1. Taken together, the work in this thesis clearly demonstrates that Stat1 plays a key role in ATRA-induced terminal differentiation of myeloid cells, through regulation of cell cycle proteins and myeloid-specific transcription factors. </p>

All-trans retinoic acid (ATRA), a biologically active metabolite of vitamin A, is a powerful inducer of terminal differentiation and growth arrest of several myeloid cell lines in vitro. Although the efficacy of ATRA as an anti-cancer drug has been demonstrated by the successful treatment of acute promyelocytic leukemia (APL), knowledge concerning the molecular mechanisms directing ATRA-induced differentiation and cell cycle arrest of myeloid cells is lacking. Our results show, for the first time, that the complex regulation of cell cycle proteins and myeloid-specific transcription factors induced by ATRA relies on functional Stat1. We found that Stat1 is activated by both tyrosine-701 and serine-727 phosphorylation upon ATRA-induced differentiation of the human monoblastic cell line U-937. Expression of phosphorylation deficient mutants of Stat1 (Stat1Y701F or Stat1S727A) inhibited both ATRA-induced differentiation and cell cycle arrest of U-937 cells, pointing to a requirement of active Stat1 in these processes. Detailed analysis of the molecular mechanism of ATRA-induced cell cycle arrest and differentiation showed that the onset of cell cycle arrest was associated with a decrease in c-Myc and cyclin E levels and upregulation of p27Kip1 and p21WAF1/CIP1. This was followed by a rapid fall in cyclin A and B and a coordinate dephosphorylation of the retinoblastoma protein (pRb). The inhibition of ATRA-induced cell-cycle arrest by constitutive expression of Stat1Y701F or Stat1S727A was associated with impaired regulation of these cyclins and p27Kip1, positioning Stat1 activation upstream of these events. To further understand the process of ATRA-induced differentiation, the regulation of myeloid-specific transcription factors was investigated during ATRA-treatment. Notably, ATRA-induced upregulation of Stat2, ICSBP and C/EBP-ε was selectively impaired in sublines expressing Stat1Y701F or Stat1S727A, suggesting an important function of these factors downstream Stat1. Taken together, the work in this thesis clearly demonstrates that Stat1 plays a key role in ATRA-induced terminal differentiation of myeloid cells, through regulation of cell cycle proteins and myeloid-specific transcription factors.