A aspergilose invasiva (AI) é a infecção por fungos filamentosos mais comum em pacientes imunodeprimidos, especialmente em transplantes de células tronco hematopoiético e neoplasias hematológicas. Objetivo: Geral: Estabelecer a comparação entre a dosagem de Galactomanana (GM), 1,3betaD-glucana (BDG) e dados tomográficos no diagnóstico da AI bem como seu papel no desfecho clínico. Específicos: 1. Verificar a sensibilidade e especificidade dos ensaios de Galactomanana e de 1,3betaD-glucana no soro e lavado broncoalveolar. 2. Comparar os resultados da galatomanana e 1,3betaD-glucana com os dados de imagem em pacientes com suspeita de AI. 3. Verificar a relação entre a evolução dos níveis de GM e desfecho clínico (óbito e sobrevida). Casuística, Materiais e Métodos: Realizou-se um estudo tipo coorte prospectiva, incluindo 398 sujeitos das diversas enfermarias de pacientes imunodeprimidos do HCFMUSP, sendo incluídos dois grupos de pacientes: 202(51%) AI e 198(49%) controles. Resultados: Dos casos, 18 (8,8%) tinham aspergilose provada, 28 (13,7%) provável e 158 possível (77,5%), de acordo a classificação de 2002 EORTC/MSG (European Organization for Research and Treatment of Cancer / Mycoses Study Group). Os sujeitos submetidos ao TCTH eram 42,7%, com neoplasias hematológicas 37%, TOS 9% e outras doenças 11,3%. Os fatores de risco associados ao desenvolvimento da AI foram neutropenia, monocitopenia, uso de corticóide, presença de doença pelo citomegalovírus e rejeição ou doença do enxerto contra o hospedeiro. O fator de risco associado à evolução para o óbito foi a presença de AI. Foram observados bons desempenhos para a GM tanto no soro como no LBA com LR menores que os registrados na literatura. O melhor desempenho da GM no soro para aspergilose+provável ocorreu com LR de 0,35 com sensibilidade-S, especificidade-E, valor preditivo positivo- VPP), valor preditivo negativo-VPN) e área sob a curva-ASC de 54,4%, 73,4%, 50,8%, 76,2% e 0,64, sendo os valores superiores para aspergilose provada tanto na S, como E, VPN. No LBA os valores de S-E-VPP-VPN-ASC para GM para LR de 0,65 para aspergilose provável + provada foram 58,3%, 92,6%, 87,5%,71,4% e 0,75, sendo na aspergilose provada os valores de S, e VPN superiores. Nesta casuística, o melhor desempenho para BDG no soro apontou para uma LR de 100 pg/mL na aspergilose provável+provada, com 54,5%, 73,4%, 50,8% e 76,2%, 0,64 respectivamente para S-E-VPP-VPN-ASC. Para BDG no LBA, a LR na aspergilose provável + provada foi de 140 pg/mL, com os mesmos valores de 46,7%, 76,7%, 70%, 55,6% e 0.62, respectivamente. Conclusão: A GM no LBA e no soro foram úteis no diagnóstico da aspergilose mediante emprego de LR menores, sendo mais sensível na LBA, principalmente em estágios iniciais da forma angioinvasiva. A persistência de GM sérica foi relacionada ao óbito em relação à negativação da mesma. A proporção de concordância entre a TC e os biomarcadores no soro e no LBA variou de 0,5 a 0,6, com pequena concordância na estatística kappa. Excelente concordância foi observada entre dois radiologistas independentes, que analisaram de maneira cega as TC de sujeitos com aspergilose provada. Nesta casuística com inclusão de doenças sistêmicas e endêmicas, a BDG teve baixo desempenho diagnóstico / Invasive aspergillosis (IA) has become the leading infectious cause of death in immunocompromised hosts, particularly in subjects under SCTH and hematologic neoplasias. Objectives: General: To compare the performance of GM and BG tests in serum and bronchoalveolar lavage fluid (BAL) and computer tomography (CT) scans in the diagnosis of IA in immunocompromised hosts as well as their role in the patient outcome. Specific: 1. To analyse the sensitivity and specificity of Galactomannan and 1,3 betaD-glucan assays in the serum and bronchoalveolar lavage. 2. To compare the results of Galactomannan and 1,3betaD-glucan assays with CT scans in patients with invasive aspergilosis. 3. To analyse the relationship between the evolution of galactomannan levels and clinical outcome (death or survival). Patients, Materials and Methods: From December 2008 to March 2013, a prospective cohort of 398 patients from several wards of immunocompromised patients of Hospital das Clínicas, Faculdade de Medicina, University of São Paulo was included classified in two groups of patients: 202 (51%) with invasive aspergillosis (IA) and 198 (49%) control patients. Results: Considering 202 cases, 18(8.8%) were subjects with proven, 28(13.7%) with probable aspergillosis and 156(77.5%), with possible aspergillosis, according to 2002 EORTC/MSG (European Organization for Research and Treatment of Cancer/Mycoses Study Group) criteria. The most common underlying disease were: HSCT (42.7%), hematologic malignancy (37%), SOT (9%), or other diseases (11.3%). The main risk factors associated with IA were neutropenia, monocytopenia, patients under corticosterois, presence of CMV disease, and rejection or graft versus host disease. The risk factor associated with death was the presence of invasive aspergillosis. Good performances for serum and BAL GM were registered with lower cutoffs in the present workin relationship to those found in the literature. The best cutoff for proven + probable aspergillosis for serum GM was observed at 0.35 vallue with Sensitivity-S, Specificity-Sp, Positive Predictive value-PPV), Negative Predictive Value-NPV) and AUC of 54.4%, 73.4%, 50.8%, 76.2% and 0.64; the values for proven aspergillosis alone were higher for S, Sp and NPV. On BAL tests for GM (cutoff value of 0.65) in proven+probable aspergillosis we observed 58.3%, 92.6%, 87.5%,71.4%, 0.75, respectively as S-Sp-PPV-NPVAUC; the sensitivity and VPN were higher in proven aspergillosis alone. In this work, the best performance in proven+probable aspergillosis for serum BDG showed 100 pg/ML as cutoff value, with 54.5%, 73.4%, 50.8%,76.2%, 0.64 for S-Sp-PPVNPV- AUC, respectively. For BAL- BDG, the cut off for proven+probable aspergillosis was 140 pg/mL, and we observed 46.7%, 76.7%, 70.0%, 55.,6%, 0.62, respectively for for S-Sp-PPV-NPV-AUC. Conclusion: The serum and BAL GM are useful tests for diagnosis in early stages of angioinvasive form at lower cutoffs; BAL GM is more sensitive. Agreement proportion between CT scan and each biomarker in the serum or BAL ranged from 0.5-0.6, with low ? index. Perfect ? statistic was observed for analysis of CT scan of subjects in proven aspergillosis by two independent radiologists, blinded for diagnosis. Persistence of serum GM was associated to death in relationship with its negativation. BDG test showed low performance in this work, where systemic and endemic diseases were included

A aspergilose invasiva (AI) é a infecção por fungos filamentosos mais comum em pacientes imunodeprimidos, especialmente em transplantes de células tronco hematopoiético e neoplasias hematológicas. Objetivo: Geral: Estabelecer a comparação entre a dosagem de Galactomanana (GM), 1,3betaD-glucana (BDG) e dados tomográficos no diagnóstico da AI bem como seu papel no desfecho clínico. Específicos: 1. Verificar a sensibilidade e especificidade dos ensaios de Galactomanana e de 1,3betaD-glucana no soro e lavado broncoalveolar. 2. Comparar os resultados da galatomanana e 1,3betaD-glucana com os dados de imagem em pacientes com suspeita de AI. 3. Verificar a relação entre a evolução dos níveis de GM e desfecho clínico (óbito e sobrevida). Casuística, Materiais e Métodos: Realizou-se um estudo tipo coorte prospectiva, incluindo 398 sujeitos das diversas enfermarias de pacientes imunodeprimidos do HCFMUSP, sendo incluídos dois grupos de pacientes: 202(51%) AI e 198(49%) controles. Resultados: Dos casos, 18 (8,8%) tinham aspergilose provada, 28 (13,7%) provável e 158 possível (77,5%), de acordo a classificação de 2002 EORTC/MSG (European Organization for Research and Treatment of Cancer / Mycoses Study Group). Os sujeitos submetidos ao TCTH eram 42,7%, com neoplasias hematológicas 37%, TOS 9% e outras doenças 11,3%. Os fatores de risco associados ao desenvolvimento da AI foram neutropenia, monocitopenia, uso de corticóide, presença de doença pelo citomegalovírus e rejeição ou doença do enxerto contra o hospedeiro. O fator de risco associado à evolução para o óbito foi a presença de AI. Foram observados bons desempenhos para a GM tanto no soro como no LBA com LR menores que os registrados na literatura. O melhor desempenho da GM no soro para aspergilose+provável ocorreu com LR de 0,35 com sensibilidade-S, especificidade-E, valor preditivo positivo- VPP), valor preditivo negativo-VPN) e área sob a curva-ASC de 54,4%, 73,4%, 50,8%, 76,2% e 0,64, sendo os valores superiores para aspergilose provada tanto na S, como E, VPN. No LBA os valores de S-E-VPP-VPN-ASC para GM para LR de 0,65 para aspergilose provável + provada foram 58,3%, 92,6%, 87,5%,71,4% e 0,75, sendo na aspergilose provada os valores de S, e VPN superiores. Nesta casuística, o melhor desempenho para BDG no soro apontou para uma LR de 100 pg/mL na aspergilose provável+provada, com 54,5%, 73,4%, 50,8% e 76,2%, 0,64 respectivamente para S-E-VPP-VPN-ASC. Para BDG no LBA, a LR na aspergilose provável + provada foi de 140 pg/mL, com os mesmos valores de 46,7%, 76,7%, 70%, 55,6% e 0.62, respectivamente. Conclusão: A GM no LBA e no soro foram úteis no diagnóstico da aspergilose mediante emprego de LR menores, sendo mais sensível na LBA, principalmente em estágios iniciais da forma angioinvasiva. A persistência de GM sérica foi relacionada ao óbito em relação à negativação da mesma. A proporção de concordância entre a TC e os biomarcadores no soro e no LBA variou de 0,5 a 0,6, com pequena concordância na estatística kappa. Excelente concordância foi observada entre dois radiologistas independentes, que analisaram de maneira cega as TC de sujeitos com aspergilose provada. Nesta casuística com inclusão de doenças sistêmicas e endêmicas, a BDG teve baixo desempenho diagnóstico / Invasive aspergillosis (IA) has become the leading infectious cause of death in immunocompromised hosts, particularly in subjects under SCTH and hematologic neoplasias. Objectives: General: To compare the performance of GM and BG tests in serum and bronchoalveolar lavage fluid (BAL) and computer tomography (CT) scans in the diagnosis of IA in immunocompromised hosts as well as their role in the patient outcome. Specific: 1. To analyse the sensitivity and specificity of Galactomannan and 1,3 betaD-glucan assays in the serum and bronchoalveolar lavage. 2. To compare the results of Galactomannan and 1,3betaD-glucan assays with CT scans in patients with invasive aspergilosis. 3. To analyse the relationship between the evolution of galactomannan levels and clinical outcome (death or survival). Patients, Materials and Methods: From December 2008 to March 2013, a prospective cohort of 398 patients from several wards of immunocompromised patients of Hospital das Clínicas, Faculdade de Medicina, University of São Paulo was included classified in two groups of patients: 202 (51%) with invasive aspergillosis (IA) and 198 (49%) control patients. Results: Considering 202 cases, 18(8.8%) were subjects with proven, 28(13.7%) with probable aspergillosis and 156(77.5%), with possible aspergillosis, according to 2002 EORTC/MSG (European Organization for Research and Treatment of Cancer/Mycoses Study Group) criteria. The most common underlying disease were: HSCT (42.7%), hematologic malignancy (37%), SOT (9%), or other diseases (11.3%). The main risk factors associated with IA were neutropenia, monocytopenia, patients under corticosterois, presence of CMV disease, and rejection or graft versus host disease. The risk factor associated with death was the presence of invasive aspergillosis. Good performances for serum and BAL GM were registered with lower cutoffs in the present workin relationship to those found in the literature. The best cutoff for proven + probable aspergillosis for serum GM was observed at 0.35 vallue with Sensitivity-S, Specificity-Sp, Positive Predictive value-PPV), Negative Predictive Value-NPV) and AUC of 54.4%, 73.4%, 50.8%, 76.2% and 0.64; the values for proven aspergillosis alone were higher for S, Sp and NPV. On BAL tests for GM (cutoff value of 0.65) in proven+probable aspergillosis we observed 58.3%, 92.6%, 87.5%,71.4%, 0.75, respectively as S-Sp-PPV-NPVAUC; the sensitivity and VPN were higher in proven aspergillosis alone. In this work, the best performance in proven+probable aspergillosis for serum BDG showed 100 pg/ML as cutoff value, with 54.5%, 73.4%, 50.8%,76.2%, 0.64 for S-Sp-PPVNPV- AUC, respectively. For BAL- BDG, the cut off for proven+probable aspergillosis was 140 pg/mL, and we observed 46.7%, 76.7%, 70.0%, 55.,6%, 0.62, respectively for for S-Sp-PPV-NPV-AUC. Conclusion: The serum and BAL GM are useful tests for diagnosis in early stages of angioinvasive form at lower cutoffs; BAL GM is more sensitive. Agreement proportion between CT scan and each biomarker in the serum or BAL ranged from 0.5-0.6, with low ? index. Perfect ? statistic was observed for analysis of CT scan of subjects in proven aspergillosis by two independent radiologists, blinded for diagnosis. Persistence of serum GM was associated to death in relationship with its negativation. BDG test showed low performance in this work, where systemic and endemic diseases were included

Introdução: No presente estudo foram avaliados biomarcadores na ocorrência de febre em pacientes neutropênicos após transplante de células tronco hematopoiéticas (TCTH). Objetivo: O objetivo principal foi avaliar os valores séricos de biomarcadores: proteína C reativa (PCR), procalcitonina (PCT) e IL-6 (interleucina-6) que possam identificar precocemente infecção em TCTH. Outro objetivo foi fatores de risco para óbito nessa população. Métodos: Os biomarcadores foram avaliados em um estudo prospectivo que incluiu 296 pacientes neutropênicos, submetidos a TCTH autólogo ou alogênico. Os biomarcadores PCT, PCR e IL-6 foram dosados nos seguintes momentos:dia da neutropenia constatada sem febre, evento febril ou hipotermia (T < 35ºC), 24 h após a febre ou hipotermia, 72 horas após a febre ou hipotermia e febre prolongada ou seja 48 horas após a coleta no momento anterior ou na persistência da febre, cinco dias após a coleta no momento anterior. Os dados clínicos e laboratoriais, foram avaliados até a evolução para alta ou o óbito, em uma planilha Excel® 2003 e foram processados pelos programas SPSS e STATA. Os pacientes foram classificados nos seguintes grupos (I- afebril; II- febre de origem indeterminada FOI e III- febre clinica ou microbiologicamente comprovada) em relação a cada marcador estudado (PCT, PCR e IL-6). Foram feitos cálculos para estabelecer área sob a curva ROC, sensibilidade, especificidade, para avaliação da febre e óbito. Para avaliar o desfecho óbito foi realizada análise multivariada com regressão logística stepwise. Resultados: Dos 296 pacientes, 190 apresentaram febre. Duzentos e dezesseis (73%) foram submetidos a transplantes autólogos e 80 (27,0%) alogênicos. Dos 80 casos de TCTH alogênicos 74 (92,6%) eram aparentados e apenas 6 (7,4%) aparentados. Dos 80 casos alogênicos 69 (86,3%) eram fullmatch e 11(13,7%) mismatch. Em relação aos grupos já citados acima, temos a seguinte distribuição: grupo I: 106 pacientes (35,8%); grupo II: 112 pacientes (37,8%) e grupo III: 78 (26,4%). Os valores de média e mediana da IL-6 no momento afebril no grupo I em relação ao grupo II (p = 0,013), apresentando valor significativamente maiores. Os níveis da PCR no grupo I diferiram de forma significativa dos encontrados no grupo III (p < 0,05). Os grupos diferiram em relação aos níveis de IL-6 e de PCR no momento febril. O grupo II apresentou concentrações de IL-6 e de PCR significativamente menores que o grupo III. Os melhores valores de corte de PCT para os momentos de coleta: febre, 24 horas após a febre, 72 horas de febre, e febre prolongada foram respectivamente: 0,32; 0,47; 0,46 e 0,35?g/L. No momento da febre a sensibilidade foi 52,3 e a especificidade 52,6 para o diagnóstico de infecção. Os melhores valores de corte de PCR para os momentos de febre, 24 horas após, 72 horas após e febre prolongada foram, respectivamente: 79, 120, 108 e 72 mg/L. No momento da febre a sensibilidade foi 55,4 e especificidade foi 55,1. Os melhores valores de corte de IL-6 para os momentos de febre, 24 h após, 72 horas após a febre e febre prolongada foram respectivamente: 34, 32, 16 e 9 pg/mL. A sensibilidade e especificidade no momento da febre foram respectivamente: 59,8 e 59,7. Na análise dos três biomarcadores no grupo de pacientes autólogos, verifica-se que só a IL-6 apresenta valores significativos nos momentos iniciais (afebril, febre e 24 horas após a febre). Os seguintes fatores de risco independentes foram identificados na análise multivariada: doador aparentado, doador não aparentado, infecção por Gram-negativo, DHL >= 390 (UI/L), ureia >= 25 (mg/dL) e PCR >= 120 (mg/L). Conclusões: IL-6 e PCR têm associação com diagnóstico precoce de infecção clinica ou microbiologicamente confirmada em neutropenia febril após TCTH. A associação dos três marcadores não apresentou nenhuma vantagem, e não melhorou a acurácia diagnóstica. A IL-6 foi o único biomarcador significativamente associado de forma precoce com infecção quando avaliado apenas pacientes submetidos a TCTH autólogos As variáveis independentes associadas com óbito foram: transplante alogênico, infecção por Gram-negativos, DHL >= 390UI/L no momento da febre e ureia >= 25 mg/dL no momento da febre e PCR >= 120 (mg/L) / Introduction: In the present study, biomarkers were assessed in the occurrence of fever in neutropenic patients upon hematopoietic stem cell transplantation (HSCT). Objective: The main objective was to assess the serum values of biomarkers: C-reactive protein (CRP), procalcitonin (PCT) and IL-6 (interleukin-6) which can early identify infection in HSCT. Another objective was risk factors for death in that population. Methods: The biomarkers were assessed in a prospective study which comprised 296 neutropenic patients submitted to autologous or allogeneic HSCT. The biomarkers PCT, CRP and IL-6 were dosed at the following moments: day of afebrile neutropenia, febrile event or hypothermia (T < 35ºC), 24 h upon fever or hypothermia, 72 hours upon fever or hypothermia and long-standing fever, that is, 48 hours upon the last sampling or at fever persistence, five days upon the last sampling. The clinical and laboratory data were assessed up to the evolution to discharge or death, in an Excel® 2003 spreadsheet and were processed by the SPSS and STATA software. Patients were classified in the following groups (I- afebrile; II- fever of unknown origin FUO and III- clinically or microbiologically proven fever) in regard to each biomarker studied (PCT, CRP and IL-6). Calculations were made to establish the area under the ROC curve, sensitivity, specificity, for the assessment of the evolution and death. In order to assess the death outcome, a multivariate analysis with stepwise logistic regression was conducted. Results: Out of the 296 patients, 190 had fever. Two hundred and sixteen (73%) were submitted to autologous transplantations and 80 (27.0%) to allogeneic ones. Out of the 80 cases of allogeneic HSCT, 74 (92.6%) were related and only 6 (7.4%) were unrelated. Out of the 80 allogeneic cases, 69 (86.3%) were fullmatch and 11(13.7%) were mismatch. In regard to the groups mentioned above, we have the following distribution: group I: 106 patients (35.8%); group II: 112 patients (37.8%) and group III: 78 patients (26.4%). The mean and median values of IL-6 at fever onset in group I in regard to group II (p = 0.013), presenting significantly higher values. The levels of CRP in group I differed significantly from those found in group III (p < 0.05). The groups differed in regard to the levels of IL-6 and CRP at fever onset. Group II presented IL-6 and CRP concentrations significantly lower than group III. The best cut-off values of PCT for sampling: fever onset, 24 hours upon fever, 72 hours of fever, and long-standing fever were, respectively: 0.32; 0.47; 0.46 and 0.35?g/L. At fever onset, sensitivity was 52.3 and specificity 52.6 for infection diagnosis. The best cut-off values of CRP for fever onset, 24 hours upon fever, 72 hours upon fever and long-standing fever were, respectively: 79, 120, 108 and 72 mg/L. At fever onset, sensitivity was 55.4 and specificity was 55.1. The best cut-off values of IL-6 for fever onset, 24 hours upon fever, 72 hours upon fever and long-standing fever were, respectively: 34, 32, 16 and 9 pg/mL. At fever onset, sensitivity and specificity were, respectively: 59.8 and 59.7. In the analysis of the three biomarkers in the group of autologous patients, it is observed that only IL-6 presents significant values at initial moments (afebrile, fever and 24 hours upon fever). The following independent risk factors were identified in the multivariate analysis: related donor, unrelated donor, Gram-negative infection, DHL >= 390 (UI/L), urea >= 25 (mg/dL) and CRP>=120 (mg/L). Conclusions: IL-6 and CRP are associated to the early diagnosis of clinically or microbiologically confirmed infection in post-HSCT febrile neutropenia. The association of the three biomarkers did not present any advantage, nor did it improve diagnostic accuracy. IL-6 was the only biomarker significantly associated at an early stage with infection when assessed only in patients submitted to autologous HSCT. The independent variables associated with death were: allogeneic transplantation, Gram-negative infection, DHL >= 390UI/L at fever onset and urea >= 25 mg/dL at fever onset and PCR >= 120 (mg/L)

Les récepteurs de type Toll (TLR) sont des récepteurs cellulaires jouant un rôle pivot dans le déclenchement de la réponse immunitaire après une infection ou une blessure, c'est-à-dire une inflammation. L'activation de la signalisation TLR a été associée à l’épilepsie. Dans ce projet, j'utilisai trois modèles distincts pour étudier comment le déclenchement des TLR contribue à l'épileptogenèse. Il existe une corrélation entre les malformations corticales développementales telle la dysplasie corticale focale (FCD) et convulsions fébriles dans les enfants de bas âge. Récemment, une réponse neuro-inflammatoire fut identifiée dans les lésions FCD. Nous postulâmes que l'inflammation induite par le FCD peut augmenter la sensibilité aux crises (chapitre 2). Nous modélisâmes FCD en induisant une congélation-lésion corticale chez le rat néonatal. La lésion corticale déclencha des effecteurs en aval de TLR4, spécifiquement le précurseur de la cytokine Caspase-1, dans l'hippocampe ipsilatéral à la lésion. Les rats lésés développèrent des crises fébriles expérimentales nettement plus rapidement que les rats témoins. Le blocage de l'activité de la Caspase-1 prolongea significativement la latence des crises chez les rats lésés. Nos résultats impliquent l'inflammation médiée par la Caspase-1 en tant que déclencheur des crises fébriles chez les enfants avec FCD préexistante. Des études antérieures déterminèrent que l'activation systémique de la cascade TLR4 abaisse le seuil de crise. Nous étudiâmes si la pénétration des cellules immunitaires périphériques dans le cerveau pendant la stimulation TLR4 favorise l'activité ictal en stimulant la voie TLR4 dans les leucocytes prélevés sur la rate de rat (splénocytes). Ensuite, nous co-cultivâmes des splénocytes avec des coupes organotypiques dérivées du cerveau in vitro (chapitre 3). L'ajout de splénocytes stimulés par TLR4 donna lieu à une neuro-inflammation et à une excitation neuronale accrue. L’ajout de splénocytes non-stimulés n’eut aucun effet pro-inflammatoire ou pro-excitateur dans les coupes organotypiques. De plus, l'inhibition de la Caspase-1 dans des coupes organotypiques co-cultivées avec des splénocytes stimulés diminua la neuro-inflammation et l'hyperexcitabilité neuronale. Nos résultats suggèrent que l'infiltration de leucocytes activés par TLR4 dans le cerveau augmente la prédisposition aux crises via les mécanismes médiés par la Caspase-1. Précédemment, des rapports montrèrent que l'activation de la signalisation TLR3 facilite l'évolution des crises. L'introduction d'un agoniste synthétique TLR3 chez la souris in vivo et des coupes organotypiques hippocampiques in vitro produisirent des mécanismes anti-inflammatoires dépendants de la dose et du temps (chapitre 4). La stimulation TLR3 supprimait les crises d'hippocampe in vivo et réduisait l'excitabilité synaptique dans le réseau hippocampique à la fois in vivo et in vitro. Nous avons déterminé que les effets anticonvulsivants médiés par TLR3 étaient principalement provoqués par les cascades en aval IRF3 / IFN-β. Ainsi, nos données suggèrent que l'activation de TLR3 peut protéger le cerveau contre les crises par la production d'IFN-β. Nos résultats donnent un aperçu des nouveaux mécanismes cellulaires sous-jacents à la modulation inflammatoire de l'excitabilité neurale. Notre découverte des rôles de la Caspase-1 et de l'IFN-β dans l'influence du seuil de crise améliorera notre compréhension des fondements moléculaires de la génération de crises ce qui pourraient améliorer le traitement de l'épilepsie. / Toll-like receptors (TLRs) are cellular receptors that play a pivotal role in initiating immune response following infection or injury, i.e. inflammation. Nevertheless, activation of TLR signaling has been associated with seizure manifestation. In this research, I employed three distinct models to study how triggering TLRs contributes to ictogenesis. There is a correlation between developmental cortical malformations, e.g. focal cortical dysplasia (FCD), and fever-provoked, i.e. febrile, seizures in young children. Recently, neuroinflammation was reported in FCD lesions. Therefore, we posited that FCD-induced inflammation may increase seizure susceptibility (Chapter 2). To recapitulate FCD pathology, we induced a cortical freeze-lesion in neonatal rats. Lesioning the cortex triggered TLR4 downstream effectors, specifically the cytokine precursor Caspase-1, in the hippocampus ipsilateral to the lesion. Further, lesioned rats developed experimental febrile seizures markedly faster than sham control rats. Strikingly, blocking Caspase-1 activity prior to seizure induction significantly prolonged seizure latency in lesioned rats. Our results implicate Caspase-1-mediated inflammation as a main driver of febrile seizures in children with pre-existing brain malformations. In addition, previous reports determined that systemic activation of TLR4 cascade lowers seizure threshold. Hence, we developed an in vitro model to investigate whether penetration of peripheral immune cells into the brain during TLR4 stimulation promotes ictogenic activity (Chapter 3). First, we stimulated TLR4 pathway in leukocytes harvested from rat spleen, i.e. splenocytes. Thereafter, we co-cultured splenocytes with brain-derived organotypic slices in vitro. Adding TLR4-stimulated splenocytes gave rise to neuroinflammation and enhanced neuronal excitation, whereas adding unstimulated splenocytes failed to evoke pro-inflammatory or proexcitatory effects in organotypic slices. Moreover, Caspase-1 inhibition in organotypic slices cocultured with stimulated splenocytes diminished neuroinflammation and neuronal hyperexcitability. Our findings suggest that infiltration of TLR4-activated leukocytes into the brain elevate seizure predisposition via Caspase-1-mediated mechanisms. Beside TLR4 pathway, it was previously shown that activation of TLR3 signaling facilitates seizure evolution. In chapter 4, introducing a synthetic TLR3 agonist to mice in vivo and to hippocampal organotypic slices in vitro yielded anti-inflammatory mechanisms in a dose- and time-dependent manner. Also, we found that TLR3 stimulation suppressed hippocampal seizures in vivo and reduced synaptic excitability in the hippocampal network both in vivo and in vitro. Finally, we determined that TLR3-mediated anticonvulsive effects were chiefly driven by IRF3/IFN-β downstream cascades. Thus, our data suggests that TLR3 activation may protect the brain from seizures through production of IFN-β. Altogether, our findings provide insight into novel cellular mechanisms underlying inflammatory modulation of neural excitability. Furthermore, our discovery of the roles of Caspase-1 and IFN-β in influencing seizure threshold will improve our understanding of the molecular underpinnings of seizure generation, which may ultimately have therapeutic benefits for epilepsy treatment.