Le rôle central de la voie mTOR (mammalian Target Of Rapamycin) dans l’homéostasie cellulaire suscite un réel intérêt dans de nombreux domaines thérapeutiques. Les inhibiteurs de mTOR (mTORi) sont utilisés en prévention du rejet de greffe par leur action d’inhibition de l’activation lymphocytaire T et l’induction de lymphocytes T régulateurs (Treg). En cancérologie, les mTORi sont utilisés pour leur action anti-proliférative et anti-angiogénique. Cependant, l’efficacité clinique de ces traitements reste modeste. Bien que des mécanismes de résistance aux mTORi intrinsèques à la cellule tumorale ont été identifiés, leur impact sur le système immunitaire émerge comme un facteur essentiel dans leur efficacité. Notre hypothèse est donc que l’efficacité anti-tumorale des mTORi serait également liée à la modulation de l’immunité anti-tumorale induite par ces traitements.Nous avons réalisé un immunomonitoring, du taux de Treg et de la réponse lymphocytaire Th1 anti-tumorale au sein d’une cohorte prospective de patients atteints de cancer rénal métastatique traités par éverolimus (mTORi).Nous avons observé une augmentation des Treg et de leur fonction suppressive à partir du 2ème mois de traitement dans la quasi-totalité des patients. Paradoxalement, une augmentation des réponses Th1 anti-tumorales a également été observée chez ces patients. Au moment de la progression tumorale, la majorité des patients ont présenté une forte augmentation des Treg associée à une perte de la réponse Th1. Ainsi, nous avons pu définir différents profils immunitaires basés sur la modulation de ces deux paramètres. Les patients présentant une diminution précoce des Treg associée à une augmentation de la réponse Th1 avaient une meilleure survie sans progression par rapport aux autres patients (13.2 vs 4 mois p= 0.02). De façon consistante, cette immunomodulation a été confirmée chez des patients atteints de tumeur neuroendocrine traités par éverolimus. De plus, l’impact du traitement sur les Treg et la réponse Th1 n’était pas influencé par la pharmacocinétique du médicament. Par la suite, nous avons étudié in vivo, chez des souris porteuses de différentes tumeurs, l’impact des mTORi sur la réponse immunitaire anti-tumorale. Comme chez les patients, nous avons observé une augmentation des Treg chez les souris traitées par mTORi. Ainsi, l’utilisation d’anticorps déplétants les Treg ou de souris transgéniques ont permis de démontrer le rôle délétère des Treg sur l’efficacité anti-tumorale des mTORi. Ces résultats suggèrent fortement que les mTORi ont un double effet sur le système immunitaire dans un contexte tumoral, un premier néfaste par l’induction d’un environnement immunosuppresseur et le second positif par l’augmentation d’une réponse Th1 anti-tumorale.Dans un deuxième travail, nous avons exploré l’effet positif des mTORi sur le système immunitaire afin d’optimiser les immunothérapies anti-tumorales. Nous avons montré que l’administration de temsirolimus (mTORi) améliore l’efficacité anti-tumorale d’un vaccin thérapeutique chez la souris. L’effet synergique de cette combinaison était lié à une augmentation de l’infiltration tumorale des LT CD8 anti-tumoraux de phénotype centro-mémoire. L’efficacité de cette combinaison a été nettement améliorée par l’addition d’un antagoniste de CCR4 permettant d’éliminer les Treg induits par le temsirolimus.En conclusion, les mTORi demeurent une stratégie prometteuse en cancérologie malgré la réduction de leur utilisation due à l’arrivée des nouvelles immunothérapies, comme les checkpoints inhibiteurs (notamment dans le cancer du rein) et d’autres thérapies ciblées (inhibiteurs de cycline dans le cancer du sein). En revanche, le futur développement des mTORi devra s’appuyer sur des biomarqueurs prenant en compte l’impact de ces traitements sur le système immunitaire et sur des combinaisons thérapeutiques notamment avec les immunothérapies / The key role of the mTOR (mammalian Target of Rapamycin) pathway in cellular homeostasis raises a real interest in many therapeutics areas. Inhibitors of mTOR (mTORi) are used for graft rejection prevention to inhibit the T lymphocyte (LT) activation and induce regulatory T cells (LTreg). In cancerology, they are used for their antiproliferative and antiangiogenic actions. However, the clinical efficacy of those treatments is low. Although several mTORi resistance mechanisms linked to the tumor cell have been identified, their impact on the immune system appears as a key factor in their efficiency. Thus, our hypothesis is that the clinical efficacy of mTORi could also be dependent of an anti-tumoral immunity modulation resulting from those treatments.We performed an immunomonitoring of the Treg rate and the tumor specific Th1 anti-tumor response among a prospective cohort of patients with a metastatic renal carcinoma treated by everolimus (mTORi). We observed that the Treg rate and the suppressive function increase after the second month of treatment for almost all the patients. Paradoxically, an increase of the Th1 anti-tumoral response has also been observed for these patients. At disease progression, a majority of the patients has shown an important increase of Treg with a decrease of the Th1 response. Thus, we have been able to define different immune profiles based on the modulation of these two parameters. Progression free survival of patients with an earlier decrease of Treg and an increase of Th1 response was significantly longer compared to other patients (13.2 vs 4 months p=0.02). This immunomodulation has been consistently confirmed with patients affected by neuroendocrine tumor and treated with everolimus. The treatment impact on Treg and the Th1 response was not related to the pharmacokinetic of the drug. Thereafter, we have studied in vivo the impact of mTORi on the anti-tumoral immune response with mice affected by different tumors. We have observed the same increase of Treg in mice treated with mTORi as the increase observed in the patients. Thus, using antibodies depleting the Treg or transgenic mice allowed us to confirm the deleterious role of Treg on the anti-tumor mTORi efficacy. Those results strongly suggest that mTORi have a double effect on the immune system, a harmful impact by the induction of an immunosuppressive environment and a positive impact by the increase of the anti-tumor Th1 response.In a second time, we have studied the positive effect of mTORi on the immune system in order to optimize the anti-tumoral immunotherapies. We have shown that the administration of temsirolimus (mTORi) improves the anti-tumoral efficiency of a therapeutic vaccination on mice. Indeed, the synergic effect of this combination is tied with an augmentation of tumor infiltrate anti-tumor T CD8 with a central memory phenotype. The efficiency of this combination has been greatly improved by the addition of an antagonist CCR4 allowing the elimination of Treg generated by temsirolimus.In conclusion, mTORi remain a promising strategy in cancerology even if their use is likely to be reduced as new immunotherapies such as checkpoint inhibitors (renal carcinoma) or other targeted therapies (cycline dependent kinase inhibitors in breast cancer) appeared. In the future, the development of mTORi must integrate biomarkers taking into account the impact of these treatments on the immune system, and therapeutic combination such as the immunotherapy

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The definitive diagnosis of strongyloidiasis is normally done by detection of larvae on faecal samples; however, the number of parasites is limited in most cases and the elimination of larvae is irregular. Thus, developing reliable serological methods for the diagnosis of strongyloidiasis becomes imperative. The aim of this study was to establish a coproantigen ,antigen, antibody and immune complex detection by enzyme-linked immunosorbent assay in serum and bronchoalveolar lavage fluid (BALF) samples of non immunosuppressed or immunosuppressed rats experimentally infected with Strongyloides venezuelensis. For kinetics of coproantigen detection (0 and 5, 8, 13 and 21 days post-infection (d.p.i)), we used an anti-L3 polyclonal antibody produced in rabbits. For antigen and immune complex detection in serum and BALF samples (0 and 2, 5, 8, 13 and 21d.p.i), the microtitre plates were coated with IgG anti-S. venezuelensis and with alkaline parasite extract for antibody detection. The statistical analysis were analyzed using Two Way ANOVA, followed by the Bonferroni test. The criterion for statistical significance was set at p<0,05. The number of eggs/g of faeces recovered at 8 d.p.i was significantly higher for non immunosuppressed and immunosuppressed animals (p<0.01). The coproantigen detection was significantly higher at 13° d.p.i in non immunosuppressed (p<0.05) and in immunosuppressed it was anticipated to the 5th d.p.i. It was observed that antigen detection in serum samples was not a good approache for evaluating the infection however in BALF samples it showed superior results. In immunosuppressed animals, IgG specific for S. venezuelensis was preferentially detected during the 5° and 13° d.p.i and in immunosuppressed animals, during the entire experimental kinetics. In BALF samples, antibodies detection was observed from the 8° to the 21° d.p.i in non immunosuppressed animals and in immunosuppressed animals it was anticipatedto the 2° d.p.i, with higher reactivity at 5° d.p.i (p<0.05). The immune complex detection in serum samples of the non immunosuppressed animals was observed from the 5° to the 13° d.p.i and in immunosuppressed animals, during the entire kinetics. In BALF samples, immune complex detection was higher in non immunosuppressed animals. In conclusion, coproantigen and immune complex detection in serum and BALF samples are alternatives for early strongyloidiasis diagnosis, mainly in immunocompromised cases. / O diagnóstico definitivo da estrongiloidíase normalmente é realizado mediante a detecção de larvas nas fezes; porém a quantidade de parasitos é limitada e a eliminação de larvas é reduzida e irregular. Sendo assim, o desenvolvimento de testes sorológicos confiáveis para o diagnóstico da estrongiloidíase torna-se uma alternativa necessária. O objetivo deste estudo foi demonstrar a cinética de detecção de coproantígenos e de antígenos, anticorpos e imunocomplexos circulantes em amostras de soro e de lavado bronco alveolar (LBA) de ratos imunossuprimidos e experimentalmente infectados por Strongyloides venezuelensis. Para a cinética (0 e 5, 8, 13 e 21 dias pós-infecção (d.p.i)) de coproantígenos utilizou-se anticorpo policlonal anti-L3 produzido em coelhos. Para a detecção de antígenos e de imunocomplexos em amostras de soro e de LBA (0 e 2, 5, 8, 13 e 21 d.p.i), placas de microtitulação foram sensibilizadas com IgG anti-S. venezuelensis e com extrato alcalino de larvas para a detecção de anticorpos. A análise estatística foi realizada por Two Way ANOVA, seguida pela teste de Bonferroni, considerando p<0,05 significativo. A cinética de eliminação de ovos/g de fezes mostrou que o pico ocorre no 8° d.p.i sendo significativamente maior nos animais imunossuprimidos (p<0,01). O pico de detecção de coproantígenos nos animais não imunossuprimidos foi no 13° d.p.i (p<0,05), sendo que nos animais imunossuprimidos a detecção foi antecipada para o 5° d.p.i. A detecção de antígeno em amostras de soro não foi uma boa ferramenta diagnóstica para avaliar a infecção enquanto que em amostras de LBA mostrou ser ferramenta auxiliar. A detecção de IgG específica para S. venezuelensis em amostras de soro de animais não imunossuprimidos foi preferencialmente durante o 5° e o 8° d.p.i. e em animais imunossuprimidos, durante toda a cinética experimental. Nas amostras de LBA, a detecção de anticorpos ocorreu do 8° ao 21° d.p.i em animais não imunossuprimidos e em animais imunossuprimidos, foi antecipada para o 2° d.p.i, como pico de reatividade no 5° d.p.i (p<0,05). A detecção de imunocomplexos em amostras de soro de animais não imunossuprimidos foi possível do 5° aos 13° d.p.i e em animais imunossuprimidos, durante toda a cinética. Em amostras de LBA, a detecção de imunocomplexo foi maior em animais não imunossuprimidos. Concluiu-se que a detecção de coproantígeno e de imunocomplexos circulantes em amostra de soro e em amostras de LBA são uma alternativa para o diagnóstico precoce da estrongiloidíase principalmente nos casos de imunossupressão. / Doutor em Imunologia e Parasitologia Aplicadas