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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1151

Rôle de la CK2 dans l’activation de la réponse immunitaire induite par les molécules allergisantes et son lien avec Nrf2 / Role of the protein kinase CK2 in the activation of immune response induced by contact sensitizers - and its link with Nrf2

Bourayne, Marie de 09 July 2015 (has links)
L’eczéma allergique de contact (EAC) est une réaction inflammatoire aiguë médiée par les lymphocytes T (LT), survenant suite à l’exposition répétée de la peau avec une molécule allergisante présente dans l’environnement quotidien ou professionnel. Les molécules allergisantes sont des composés de faible poids moléculaire, appelés haptènes, qui activent les cellules dendritiques (DC). Les DC jouent un rôle essentiel dans la mise en place d’un EAC : elles acquièrent un phénotype mature, contrôlé par la voie des MAPK et la voie NF-B, leur permettant de présenter l’haptène aux LT afin d’initier ainsi une réponse immunitaire spécifique.Nous avons identifié au sein de la DC une nouvelle kinase, la protéine kinase CK2, indispensable à l’acquisition d’un phénotype mature et à la sécrétion de cytokines pro-inflammatoires clés dans l’orientation d’une réponse immunitaire. L’activité de la CK2 dans la DC est nécessaire à la génération d’une réponse Th1 en contrôlant la sécrétion d’IFN par les LT, et maintient une réponse Th17 préexistante. De plus, la CK2 permet à la DC de contrôler l’induction d’une réponse Th2 spontanée. Par ailleurs, la CK2 contrôle l’expression des gènes cibles de Nrf2, un facteur de transcription majeur dans la lutte contre le stress chimique induit par les haptènes. L’activation de Nrf2 met en jeu de nombreuses voies de signalisation, et nous avons mis en évidence c-Jun, facteur de transcription activé par les molécules allergisantes, comme un potentiel partenaire transcriptionnel de Nrf2. / Allergic contact dermatitis represents a severe health problem with increasing worldwide prevalence. It is a T cell-mediated inflammatory skin disease caused by chemicals present in daily or professional environment. Contact sensitizers are low molecular weight compounds termed haptens. These molecules are known to induce an up-regulation of phenotypic markers and cytokine secretion in dendritic cells (DCs), professional antigen-presenting cells, leading to the generation of effector T lymphocytes (LT).We identified a new kinase, termed CK2 (formerly casein kinase 2), as a key kinase in DCs in the acquisition of a mature phenotype and in the production of pro-inflammatory cytokines, involved in T cell polarization in response to contact sensitizers. CK2 activity in DC is necessary to induce a Th1 polarization by controlling the secretion of IFN- by LT, and maintains a pre-existing Th17 response. Moreover, CK2 in DC negatively controls a spontaneous Th2 response.Finally, CK2 controls the expression of Nrf2 target genes mRNA. Nrf2 is a protective transcription factor playing a major role in detoxification, oxidative stress and allergic inflammation generated by contact sensitizers. Nrf2 activation involves different kinases and we highlight that c-Jun could be bound to Nrf2 to generate an active transcriptional complex in response to chemicals.
1152

Traitement anticancéreux et modulation du système immunitaire / Effects of Anticancer Agents on Immune Responses

Zoubir, Mustapha 06 April 2012 (has links)
Les thérapies anticancéreuses ont apporté un gain largement reconnu en matière de réduction de la charge tumorale, de survie des patients et d’amélioration de leur qualité de vie, dans un certain nombre de cancers. Hélas, ces thérapies exercent un effet immunosuppresseur en détruisant les effecteurs ou en bloquant l’activité de certains facteurs biologiques impliqués dans le recrutement des acteurs du système immunitaire. D’autre part, plusieurs travaux ont permis de démontrer que ces traitements pouvaient avoir un effet contraire en générant ou en favorisant l’induction d’une réponse immunitaire anti-tumorale, soit par effet direct sur le recrutement et l’activation des effecteurs de l’immunité, soit en potentialisant les interactions cellulaires par des mécanismes biologiques. Ces derniers faisant intervenir les cytokines, la stimulation des TLR, l’augmentation des interactions entre cellules du SI; ce qui permet de passer d’une anergie immunologique vers un véritable système d’éradication des cellules cancéreuses.Dans notre laboratoire, nous avons essayé d’évaluer l’implication du système immunitaire dans la réponse thérapeutique induite par des agents cytotoxiques conventionnels. Ici, nous décrivons les effets d’un inhibiteur de cyclines kinases multi-cibles « CDKi PHA-793 887 » testé dans un essai de phase I mené sur deux sites en Europe. C’est le constat inattendu que 6 des 15 patients, traités par ce médicament (PHA-793887) ont développé de graves infections bactériennes et virales et que 6 d’entre eux ont présenté la réactivation du virus de l’herpès qui nous a conduit à étudier ces effets sur le système immunitaire et en particulier sur le dialogue entre cellules dendritiques (CD) et cellules natural killer (NK). Ce travail met en évidence que ce médicament inhibe le signalling des récepteurs toll-like (TLR) réduisant par conséquent l’interaction CD/NK in vitro. Enfin la stimulation des cellules des patients sous traitement démontre une réduction importante de ce signalling ex-vivo. Ainsi, cet effet immunosuppresseur inattendu a permis une réactivation virale chez 40% des patients. La deuxième partie de ce travail, concerne les effets du cyclophosphamide (CTX) utilisé à faible dose. L’injection d'une faible dose chez la souris ou d’un dosage métronomique chez l'homme, promeut la différenciation des cellules lymphocytaires vers Th17 (sécrétant de l’interleukine-17 (IL-17)) et Th1 (sécrétant de l’interféron-γ (IFN)). Ceux-ci ont été retrouvés dans le sang et dans des ascites carcinomateuses de patients. Ainsi, le CTX pourrait participer à la génération de réponses anti-tumorale via la différenciation Th 17 comme cela fut suggéré par de récentes études précliniques montrant l’existence d’une corrélation étroite entre le taux des lymphocytes Th17 infiltrant la tumeur et la destruction tumorale. / Cancer therapies have made a gain widespread recognition in the reduction of tumor burden, patient survival and improved quality of life in a number of cancers. Unfortunately, these therapies exert an immunosuppressive effect by killing effectors or blocking the activity of certain biological factors involved in recruiting of the immune system. On the other hand, several studies have shown that these treatments could have the opposite effect by generating or promoting the induction of antitumor immune response, either by direct effect on the recruitment and activation of effectors immunity, either by potentiating cellular interactions by biological mechanisms. The latter involving cytokines, TLR stimulation, increased interactions between cells of the IS; which toggles between immunological anergy to a real system to eradicate cancer cells. In our laboratory, we tried to evaluate the involvement of the immune system in the therapeutic response induced by conventional cytotoxic agents. Here, we describe the effects of an inhibitor of cyclin kinases multi-target "CDKIs PHA-793887" tested in a phase I trial conducted at two sites in Europe. This unexpected finding is that 6 of 15 patients treated with this drug (PHA-793887) developed severe bacterial and viral infections and six of them showed reactivation of the herpes virus that has led us to study these effects on the immune system and in particular on the dialogue between dendritic (DCs) and natural killer (NK) cells. This work shows that this drug inhibits the signaling of toll-like receptor (TLR) thereby reducing the interaction DC / NK in vitro. Finally, stimulation of the cells of treated patients demonstrated a significant reduction of this signaling ex vivo. Thus, this immunosuppressive effect has an unexpected viral reactivation in 40% of patients. The second part of this work concerns the effects of metronomic dose of cyclophosphamide (CTX). The injection of a low dose in mice or metronomic dosing in humans, markedly promotes the differentiation of CD4+ T helper 17 (Th17) cells that can be recovered in both blood and tumor beds. However, CTX does not convert regulatory T cells into Th17 cells and promotes cell differentiation into Th17 lymphocytes (secreting interleukin-17 (IL-17)) and Th1 (secreting interferon-γ (IFN)). These were found in blood and in ascites carcinoma patients. Thus, CTX may participate in the generation of antitumor responses through Th 17 differentiation as was suggested by recent preclinical studies showing the existence of a correlation between the rate of Th17 lymphocytes infiltrating the tumor and tumor destruction.
1153

Células dendríticas plasmocitóides, expressão de receptores \"Toll-like\" 9 e 3 e de podoplanina nas lesões cutâneas do Sarcoma de Kaposi associado à síndrome de imunodeficiência adquirida e esporádico / Plasmacytoid dendritic cells and the expression of toll-like receptors 9 and 3 and podoplaninin in cutaneous lesions of Aids-associated Kaposi\'s sarcoma and classic Kaposi\'s sarcoma

Soares, Cinara Prata Cirino Castro 25 August 2014 (has links)
INTRODUÇÃO: O Sarcoma de Kaposi (SK) é a neoplasia mais frequente dos doentes com Aids. É causada pelo herpes-vírus 8 (HHV-8). As células dendríticas plasmocitóides (CDp) são especializadas na produção de interferon tipo 1 e participam da resposta imune aos vírus. Os receptores \"toll-like\" são os principais receptores de reconhecimento de padrão, sendo que os receptores toll-like (TLR) 3 e 9 têm função no reconhecimento de vírus. O D2-40 é o anticorpo que reconhece a podoplanina, uma proteína transmembrana, presente no endotélio linfático e que tem função na imunidade. OBJETIVO: Demonstrar e comparar os componentes da imunidade inata: CDp e TLR 3 e 9, nas lesões cutâneas de SK associado a Aids e esporádico. Identificar a presença do HHV-8 nas CDp. Verificar o componente endotelial linfático na progressão das lesões de SK e comparar a expressão dos elementos da imunidade inata estudados, nas lesões com menor e maior componente endotelial linfático. MÉTODOS: Estudo retrospectivo de 50 biopsias de pacientes com diagnóstico de SK, todos com comprovação pelo exame histopatológico e demonstração do antígeno nuclear associado à latência (LANA) do HHV-8. Foram avaliados 11 biopsias de SK da forma clássica (SKc), 22 lesões de doentes com Aids (SK-Aids) e de 17 de doentes com Aids submetidos a tratamento com terapia antirretroviral altamente eficaz (SK-Aids/HAART). Os espécimes foram submetidos a exame por técnica imuno-histoquímica para evidenciar a presença de CDp (anticorpo CD303/BDCA-2), a expressão de TLR 3 e 9, bem como de podoplanina (anticorpo D2-40). Foi realizada também técnica de dupla marcação com CD303 e LANA, objetivando a identificação de CDp infectadas pelo HHV-8.Vinte e três espécimes de granuloma piogênico constituíram o grupo controle. A população de CDp e expressão de TLR 3 e TLR 9 também foi comparada nas lesões cutâneas de SK de doentes com e sem comprometimento visceral pela neoplasia; lesões não tumorais (máculo-papulares/placas) foram comparadas às lesões tumorais (nodulares) e de acordo com níveis sanguíneos de linfócitos T CD4+ (menor e igual ou maior que 350 células/mm3). RESULTADOS: As CDp foram mais numerosas nos espécimes de SK-Aids quando comparado com o granuloma piogênico. Foram identificadas CDp infectadas pelo HHV-8. A expressão de TLR 3 foi menor nas lesões de SK, independente da forma epidemiológica, do que no granuloma piogênico. Para todas as outras comparações da densidade de CDp e expressão de TLR 3 e de TLR 9 não houve diferença entre os grupos. Não houve diferença no componente endotelial linfático das lesões máculo-papulares/placas e tumorais do SK, assim como na expressão dos elementos da imunidade inata estudados entre as lesões com maior e menor componente endotelial linfático. CONCLUSÕES: Demonstrou-se pela primeira vez a presença de CDp e a expressão de TLR 3 e 9 em lesões cutâneas do Sarcoma de Kaposi, bem como a infecção de CDp pelo HHV-8 \"in situ\" nos tumores. Os resultados obtidos sugerem a participação das células CDp e do TLR 3 na patogênese das lesões cutâneas do Sarcoma de Kaposi, independente da presença do vírus da imunodeficiência humana. A imunomarcação de SK com o anticorpo D2-40, tanto nas fases precoce como tardia das lesões, confirma a natureza endotelial linfática das células neoplásicas. Esta parece não ter relação com a expressão dos elementos da imunidade inata estudados / Introduction: Kaposi\'s sarcoma (KS) is the most common Aids-associated malignancy. It is caused by human herpesvirus-8. Plasmacytoid dendritic cells (pDC) are professional interferon producing cells, and participate in the immune response against viruses. Toll-like receptors (TLR) are the main pattern recognition receptors, and TLR 3 and TLR 9 participate in the recognition of viruses. Podoplanin, recognized by antibody D2-40, is a transmembrane protein identified on lymphatic endothelial cells with functions inimmunity. Objective: Demonstrate and compare some innate immunity components: pDC, TLR 3 and TLR 9, in cutaneous lesions of Aids-associated Kaposi\'s sarcoma and classic Kaposi\'s sarcoma. Identify the infection of pDC by HHV-8. Compare the lymphatic endothelial component in the course of tumor progression and compare the expression of innate immunity elements in lesions with a predominance of lymphatic endothelial components or not. Methods: Retrospective study of 50 biopsies diagnosed as Kaposi\'s sarcoma withpositive staining for latency-associated nuclear antigen (LANA) of HHV-8. Eleven classic KS, 22 Aids-associated KS and 17 Aids-associated KS from patients undergoing highly active antiretroviral therapy (HAART) were assessed. Paraffinembedded tissue was submitted to immunohistochemistry technique in order to demonstrate pDC (CD303/BDCA-2 antibody), expression of TLR 3, TLR 9 and podoplanin (D2-40 antibody). We performed double staining with CD303 and LANA in order to identify pDC infection with HHV-8. Twenty-three pyogenic granuloma(PG) specimens were analyzed as a control group. Plasmacytoid dendritic cells population, TLR 3 and TLR 9 expressions were compared between patients with and without visceral disease, nodular stageandpatch/plaque stage and according to bloodlymphocytes T CD4 count(=350 cells/mm3). Results: Plasmacytoid dendritic cells density in Aids-associated SK was higher than in PG. We could identify pDC infection by HHV-8. The expression of TLR 3 in all forms of KS was less extensive than PG. All others comparisons about pDC density, TLR 3 and 9expressions were similar. We found no difference in D2-40 expression between nodular and patch/plaque stages. When comparing tumors with extensive expression of D2-40 (>= 50% of cells) and tumors with less expression (<50% of cells), we found no differences in density of pDC and expression of TLR 3 and TLR 9. Conclusion: This is the first time that pDC, TLR 3 and TLR 9 have been demonstrated in skin lesions of KS, as well as the infection of pDC in the lesions. Our results suggest that pDC and TLR 3 participate in the pathogenesis of KS, independently of HIV presence. The positive staining with D2-40 antibody, in all the stages of KS, confirmsthe lymphatic nature of neoplastic cells. It seems that podoplanin is not related to the innate immunity elements studied here
1154

Etude de redondances mises en place par le système immunitaire pour lutter contre l'infection par le cytomégalovirus murin / Study of redundancies established by the immune system for the protection during murine cytomegalovirus infection

Cocita, Clément 21 October 2015 (has links)
Chez la souris, les cellules dendritiques plasmacytoïdes (pDC) et natural killer (NK) contribuent à la résistance contre les infections systémiques par les virus herpétiques tels que le cytomégalovirus murin (MCMV). Les pDC représentent la source majeure d’interférons de type I (IFN-I) lors d’une infection par le MCMV. Cette réponse est dépendante de MyD88 et des récepteurs de type Toll 7 et 9. D’autre part, les cellules NK, qui expriment le récepteur d’activation Ly49H, peuvent détecter et lyser les cellules infectées par le MCMV. La perte de l’une de ces réponses augmente la sensibilité à l’infection. Cependant, la façon dont ces réponses antivirales interagissent est mal connue. Chez l’homme, bien que les réponses dépendantes des IFN-I soient essentielles, MyD88 semble superflu pour l’immunité antivirale. Cependant, les mécanismes susceptibles de compenser l’absence de MyD88 chez l’homme sont inconnus. Il a été supposé que les souris déficientes pour MyD88 ne parvenaient pas à monter de réponse protectrice dépendante des IFN-I lors d’infections par le MCMV. Afin d’évaluer cela, nous avons comparé la résistance de souris déficientes pour MyD88, les récepteurs aux IFN-I (IFNAR) et/ou Ly49H lors de cette infection. La déplétion sélective des pDC ou l’absence de MyD88 diminue drastiquement la production d’IFN-I, mais n’empêche pas l’établissement d’une forte réponse aux IFN-I dans la rate. De plus, l’absence de MyD88, mais pas celle d’IFNAR, peut être compensée par l’activité antivirale des cellules NK dépendant de Ly49H. Par conséquent, chez la souris, MyD88 est redondant pour l’établissement d’une réponse splénique aux IFN-I lors d’une infection systémique par le MCMV. / In mice, plasmacytoid dendritic cells (pDC) and natural killer (NK) cells both contribute to resistance to systemic infections with herpes viruses including mouse Cytomegalovirus (MCMV). pDCs are the major source of type I IFN (IFN-I) during MCMV infection. This response requires pDC-intrinsic MyD88-dependent signaling by Toll-Like Receptors 7 and 9. Provided that they express appropriate recognition receptors such as Ly49H, NK cells can directly sense and kill MCMV-infected cells. The loss of any one of these responses has been reported to increase susceptibility to infection. However, the relative importance of these antiviral immune responses and how they are related remain unclear. In humans, while IFN-I responses are essential, MyD88 appears to be dispensable for antiviral immunity. However, the mechanisms that could compensate MyD88 deficiency in humans have not been elucidated. Moreover, it has been assumed, but not proven, that MyD88-deficient mice fail to mount protective IFN-I responses to systemic herpes virus infections. To address these issues, we compared resistance to MCMV infection between mouse strains deficient for MyD88, the IFN-I receptor (IFNAR) and/or Ly49H. We show that selective depletion of pDC or genetic deficiencies for MyD88 drastically decreased production of IFN-I, but not the protective antiviral responses mediated by these cytokines. Moreover, MyD88, but not IFNAR, deficiency could be compensated by Ly49H mediated antiviral NK cell responses. Thus, contrary to the current dogma, but consistent with the situation in humans, we conclude that, in mice, MyD88 is redundant for splenic IFN-I responses against a systemic herpes virus infection.
1155

Etude de l’interaction de Mycoplasma hominis PG21 avec les cellules dendritiques humaines. : Caractérisation de la fraction bioactive du mycoplasme et réponse immunitaire innée de la cellule / Interaction of Mycoplasma hominis PG21 with human dendritic cells : bioactive fraction of the mycoplasma and innate immune response of the cells

Goret, Julien 07 December 2015 (has links)
Mycoplasma hominis est une bactérie opportuniste qui peut être responsable d’infections du tractus urogénital, d’infections néonatales ou d’infections disséminées notamment chez les patients immunodéprimés. La membrane des mycoplasmes constitue l’interface d’interaction directe avec le milieu extérieur en raison de l’absence de paroi. Cette membrane contient de nombreuses lipoprotéines qui ont le pouvoir d’activer des cellules dendritiques humaines (hDCs), d’induire la production de cytokines et de polariser le système immunitaire adaptatif. Nous avons étudié l’interaction de M. hominis PG21 avec les hDCs en nous penchant d’une part sur la fraction du mycoplasme qui active les hDCs et d’autre part sur la réponse immunitaire innée des hDCs. Apres avoir déterminé les lipoprotéines contenues dans un extrait TX-114 de M. hominis PG21, nous avons enrichi en lipoprotéines bioactives une fraction de vésicules membranaires du mycoplasme par une double extraction utilisant deux détergents non dénaturants, le Sarkosyl puis le Triton X-114. Apres séparation par SDS-PAGE, nous avons identifié vingt lipoprotéines qui pourraient entrainer la sécrétion d’IL-23 par les hDCs, notamment la lipoprotéine MHO_4720. Un lipopeptide synthétique correspondant à la fraction N-terminale de MHO_4720 est capable de stimuler les hDCs. En analysant les variations transcriptionnelles des gènes codant pour les 48 lipoprotéines de M. hominis PG21 par qRT-PCR, nous avons également déterminé que 21 lipoprotéines sont surexprimées après 4h ou 24h de contact entre le mycoplasme et les hDCs. Enfin, la réponse cellulaire a été évaluée par PCR array et ELISA. Nous avons observé l’activation d’inflammasome(s) par la mise en évidence de la production d’IL-1β dépendant de la caspase 5. / Mycoplasma hominis is involved in urogenital tract infections, neonatal infections or disseminated infections particularly in immunocompromised patients. Mycoplasmas have no cell wall and their membrane is the main interface mediating the interaction between the mycoplasma and its environment. Lipoproteins that are anchored to the extracellular side of the plasma membrane are known to induce the maturation of human dendritic cells (hDCs), to stimulate the pro-inflammatory cytokine production by hDCs and to polarize the adaptive immune system. We studied the interaction of M. hominis PG21 with hDCs in order to assess the lipoproteins that can induce the stimulation of hDCs, to determine the lipoproteins that are regulated upon interaction of the mycoplasma with the host cell and to evaluate the innate host cell response. Using a double extraction strategy with two non-denaturing detergents, Sarkosyl then Triton X-114, and separation by SDS-PAGE, we found that 20 lipoproteins may induce the secretion of IL-23 by the hDCs, especially the MHO_4720 lipoprotein. We showed that a synthetic lipopeptide corresponding to the N-terminus part of the MHO_4720 lipoprotein can stimulate the hDCs in a dose-dependent manner. Using qRT-PCR for the evaluation of the transcriptional regulation of the 48 lipoprotein-coding genes of M. hominis PG21, we also determined that 21 lipoproteins were upregulated upon 4h and 24h of contact of M. hominis with hDCs. Finally, the hDC innate immune response was evaluated by PCR array and ELISA. We observed a caspase 5-dependent production of IL- 1β corresponding to the activation of an inflammasome.
1156

Avaliação da resposta tecidual \"in situ\" do fenótipo, da expressão de HHV-8/LANA e de citocinas em lesões cutâneas de sarcoma de Kaposi clássico e sarcoma de Kaposi associado à AIDS na era pré e pós-terapia anti-retroviral combinada / Evaluation of tissue response \"in situ\" of the phenotype, expression of HHV-8/LANA and cytokines in cutaneous lesions of classic Kaposi sarcoma and AIDS associated Kaposi sarcoma in the pre-and post- highly active antiretroviral therapy era

Fernanda Guedes Luiz 15 December 2008 (has links)
Sarcoma de Kaposi (SK) é um tumor de origem vascular associado ao herpesvírus 8 humano (HHV-8). A incidência do SK-AIDS tem diminuído após o advento da terapia anti-retroviral combinada (HAART), sem estudos relacionando a resposta inflamatória cutânea e a expressão de HHV-8 na era pré e pós HAART. Utilizamos a immuno-histoquímica para caracterizar e quantificar in situ as células inflamatórias, o padrão de citocinas e a expressão de HHV-8 em lesões cutâneas de sarcoma de Kaposi clássico (SKC), sarcoma de Kaposi associado à AIDS (com ou sem HAART). O número diminuído de linfócitos TCD4+ em lesões de SK-AIDS quando comparado com SKC, reflete a imunodeficiência severa causada pelo HIV. O número de linfócitos TCD8+ foi similar nos três grupos de SK, o qual parece não se correlacionar com a forma clínico-epidemiológica do SK. As células S100+ e DD FXIIIa+ estiveram aumentadas em todas as lesões de SK comparadas com a pele normal. Nós também encontramos uma população celular dérmica S100+CD1a- peculiar nas lesões de SK. Os macrófagos CD68+ estiveram aumentados nas lesões de SKC quando comparados com as lesões de SK-AIDS, mas similares com aqueles encontrados em lesões de SK-AIDS/HAART. Dados semelhantes foram encontrados nas células de Langerhans epidérmicas nesses grupos, sugerindo uma recuperação immune parcial através da HAART. O número aumentado de células expressando IFN- em lesões de SKC e SK-AIDS/HAART quando comparado com SK-AIDS sugere essa citocina como um indicador de resposta imune mais eficaz. A expressão aumentada de IL-1 nas lesões de SKC e SK-AIDS/HAART poderia estar relacionada ao seu efeito anti-tumoral. A expressão de TNF-, IL-4 e IL-6 foram similares entre as lesões de SK avaliadas. Através de dupla marcação, a identificação nuclear de HHV-8 em DD FXIIIa+ sugere esse tipo celular como alvo para infecção por HHV-8. As lesões de SKC apresentaram número aumentado de células com expressão de HHV-8 quando comparado com os grupos de SK-AIDS, independente da HAART. Nosso estudo mostra que existiu uma recuperação da resposta immune local nas lesões de SK-AIDS/HAART e que a severidade clínica do SK não pode estar diretamente associada com a densidade aumentada de células infectadas pelo HHV-8 no tecido / Kaposis sarcoma (KS) is a vascular-originated tumor associated to human herpesvirus 8 (HHV-8). The incidence of AIDS-KS has decreased after the advent of highly active antiretroviral therapy (HAART), without studies regarding cutaneous inflammatory response and HHV-8 expression in pre- and post-HAART era. We used immunohistochemistry to characterize and to quantify in situ inflammatory cells, its cytokines pattern and the expression of HHV-8 in cutaneous lesions of classic Kaposis sarcoma (CKS), AIDS associated Kaposis sarcoma (with or without HAART). The decreased number of T CD4+ lymphocytes in lesions of AIDS-KS as compared with CKS, reflect the severe immunodeficiency caused by HIV. T CD8+ lymphocytes numbers were similar in three KS groups, which appeared unrelated to the clinical or epidemiological type of KS. S100+ cells and FXIIIa+ DD were increased in all KS lesions as compared with normal skin. We also found a peculiar dermal cellular population in KS lesions. CD68+ macrophages were higher in CKS lesions as compared with AIDS-KS lesions, but similar to those found in lesions of HAART/AIDS-KS. Similar data were found in epidermal Langerhans cells in these groups, suggesting a partial immune recovery by HAART. The high number of cells expressing IFN- in CKS lesions and HAART/AIDS-KS as compared with AIDS-KS suggests that this cytokine may be a marker of effective immune response. The increased expression of IL-1 in CKS lesions and HAART/AIDS-KS could be related with its anti-tumor effect. Expression of TNF-, IL-4 e IL-6 were similar between KS lesions. Demonstrated by double-immunostaining, nuclear identification of HHV-8 in FXIIIa+ DD suggests this cell type as target for HHV-8 infection. CKS lesions showed increased number of cells with HHV-8 expression as compared with another groups of AIDS-KS, independent of HAART. Our data shown that there was a partial recovery of local immune response in HAART/AIDS-KS lesions and that the KS clinical severity cannot be directly associated with the increased density of HHV-8 infected cells in tissue
1157

Étude in vitro et ex vivo de la réponse des cellules dendritiques à l’infection par le virus Lassa / Ex vivo and in vitro study of dendritic cell response to Lassa virus

Schaeffer, Justine 20 November 2018 (has links)
Le virus Lassa (LASV) induit une fièvre hémorragique chez l’homme et est responsable de 3 000 à 5 000 décès par an. Aucun vaccin ou traitement efficace contre LASV n’est disponible, et les mécanismes de pathogenèse de la fièvre de Lassa sont encore mal compris. Des études chez l’homme et le primate suggèrent que la réponse interféron de type I (IFN-I) et de la réponse T sont critiques pour la survie de l’hôte. Nous nous sommes intéressés à la réponse des cellules dendritiques (DC) à LASV, car elles peuvent à la fois produire des IFN-I et induire la réponse T. Nous avons étudié les DC plasmacytoïdes (pDC), spécialisées dans la réponse IFN-I, et les DC myéloïdes (mDC), présentatrices d’antigènes. Nous avons montré que les pDC et les mDC ne sont pas productivement infectées par MOPV et LASV. Les pDC produisent des quantités importantes d’IFN-I en réponse à MOPV, mais pas à LASV. Les mDC sont activées et produisent des IFN-I en réponse à MOPV mais aussi à LASV. Cependant, seules les mDC infectées par MOPV sont capables d’activer des lymphocytes T. De plus, la présence de lymphocytes T inhibe complètement l’activation des mDC infectées par LASV. Ces différences entre les mDC infectées par MOPV et LASV dépendent de la nucléoprotéine de LASV, qui est connue pour ses propriétés immunosuppressives, mais aussi de la glycoprotéine. En résumé, nous avons obtenu des différences de réponse à l’infection par MOPV ou LASV chez les pDC et les mDC. Ces cellules pourraient avoir un rôle essentiel in vivo dans la réponse globale à LASV, et donc dans l’issue de la fièvre de Lassa / Lassa virus (LASV) is responsible for a viral haemorrhagic fever in humans and the death of 3,000 to 5,000 people every year. There is currently no vaccine or treatmentavailable against LASV, and its pathogenesis is not completely understood yet. According to studies on humans and primates, type I interferon (IFN-I) and T cell responses appear to be critical for the host. We studied the response of dendritic cells (DC) to LASV, as DC are involved in both IFN-I production and T cell activation. We compared the response of primary human DC to LASV and Mopeia virus (MOPV), which is similar to LASV, but non-pathogenic.We focused on plasmacytoid DC (pDC), specialized in IFN-I production, and myeloid DC (mDC), specialized in antigen presentation. We showed that neither pDC nor mDC were productively infected by LASV and MOPV. pDC infected with MOPV produced large amounts of IFN-I, whereas pDC infected with LASV did not. mDC produced substantial amounts of IFN-I in response to both LASV and MOPV. However, only MOPV-infected mDC were able to activate T cells. More surprisingly, coculture with T cells completely inhibited the activation of LASV-infected mDC. These differences between LASV- and MOPV-infected mDC were mostly due to LASV nucleoprotein, which has major immunosuppressive properties, but the glycoprotein was also involved. Overall, these results showed differences in pDC and mDC response to MOPV and LASV. Therefore, both pDC and mDC may be important for the global response to LASV in vivo, and play a role in the outcome of Lassa fever
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Impact du VEGF sur les altérations synaptiques dans la maladie d’Alzheimer / VEGF impact on synaptic alterations in Alzheimer's disease

Martin, Laurent 06 December 2018 (has links)
La maladie d’Alzheimer est caractérisée par un déclin progressif des capacités cognitives. Les Aßo induisent des dysfonctionnements de la transmission via une altération des récepteurs au glutamate et une perte de synapses.Nos récents résultats démontrent que le VEGF facilite la plasticité synaptique et la mémoire chez des souris via son action sur son récepteur VEGFR2. Nous avons montré que le VEGF stimule l’insertion synaptique des récepteurs glutamatergiques et la formation de synapses, suggérant ainsi un rôle dans la modulation des altérations synaptiques observées dans la maladie d’Alzheimer.Notre objectif est d’étudier le rôle du VEGF, spécifiquement dans la maladie d’Alzheimer. Tout d’abord, nous avons examiné son expression en relation avec les plaques séniles chez des patients et dans un modèle de la maladie d’Alzheimer. Nos résultats ont démontré une colocalisation entre le VEGF et ces plaques.Afin d’examiner plus finement l’interaction Aß-VEGF, nous avons analysé la liaison entre les Aßo et le VEGF en test ELISA et puces à peptides. Nous avons ainsi démontré un potentiel blocage de l’interaction entre le VEGF et son récepteur, menant à des défauts de son activation.Enfin, nous avons examiné si le VEGF prévient les altérations synaptiques par des approches électrophysiologiques, biochimiques et immunocytochimiques. Nos résultats démontrent que lors d’un traitement aux Aßo, le VEGF restaure la LTP, l’expression des récepteurs au glutamate et limite la perte synaptique.Dans l’ensemble, nos résultats suggèrent que l’interaction Aß-VEGF altère la voie du VEGF chez les patients. De plus, le VEGF réduit la toxicité induite par les Aßo sur les synapses / Alzheimer disease (AD) is characterized by a progressive decline in cognitive abilities. Amyloid-ß oligomers (Aßo) trigger synapse dysfunction through defects in glutamate receptor function and subsequent dendritic spine loss. These synaptic impairments compromise memory and contribute to cognitive deficits.Our recent findings revealed that VEGF facilitates synaptic plasticity and memory in mice through its VEGFR2 receptor in neurons. We showed that VEGF promotes glutamate receptor synaptic insertion and stimulates dendritic spine formation, suggesting it may be a key candidate for alleviating synapse damage in AD.Our objective is to study the role of VEGF in synapse protection in AD models and unravel the underlying mechanisms.First, we examined the VEGF expression pattern in postmortem brain tissue from AD patients and APPPS1 model of AD. Our results showed a partial colocalization between VEGF and Aß plaques in AD patients and APPPS1 brains.To further investigate the Aß-VEGF interaction, we used Elisa assay and peptide arrays and demonstrated that Aßo binds several domains of VEGF, impedding VEGFR2 activation.Finally, we examined whether VEGF can prevent synapse damage induced by Aßo using electrophysiological, biochemical and 3D modelling approaches. Our results demonstrated that VEGF treatments can restore LTP in Aßo-treated hippocampal slices, glutamate receptor content at synapses and increase dendritic spine density.All together, our results suggest that Aß-VEGF interaction may alter VEGF pathway in AD and that VEGF reduces Aßo-induced toxicity at synapses by modulating glutamate receptor expression and promoting spine formation and/or stabilization
1159

Efeito da saliva de Aedes aegypti sobre a diferenciação, maturação e função de células dendríticas e na proliferação de linfócitos T. / Effect of Aedes aegypti saliva on the differentiation, maturation and function of dendritic cells and on T lymphocyte proliferation.

Bizzarro, Bruna 15 June 2012 (has links)
Mosquitos são os mais importantes vetores de patógenos humanos, transmitindo um amplo espectro de doenças infecciosas emergentes e reemergentes. Nesse cenário, o mosquito Aedes aegypti está entre as espécies mais relevantes. No presente estudo investigamos as atividades do extrato de glândula salivar (EGS) desse mosquito vetor na biologia das células dendríticas e dos linfócitos T. Nossos dados revelam que o EGS não interfere na diferenciação, maturação e função de células dendríticas murinas. Entretanto, componentes salivares desse mosquito possuem um efeito direto sobre linfócitos. O mecanismo de ação do EGS envolveu a apoptose de células T naïve, enquanto células de memória foram mais resistentes a essa atividade. Uma molécula com peso molecular acima de 400 kDa é provavelmente a responsável por esse efeito. Em conjunto, os resultados gerados por esse trabalho contribuem com a elucidação dos efeitos biológicos da saliva de Ae. aegypti na imunidade de seus hospedeiros e, conseqüentemente, seu papel na transmissão de doenças. / Mosquitoes are the most important vectors of human pathogens, transmitting a wide range of emerging and re-emerging infectious diseases. In this scenario, Aedes aegypti is a relevant mosquito species. In the present study, we have investigated the activities of the salivary gland extract (SGE) of this mosquito vector on the dendritic cell and T lymphocyte biology. Our data reveals that the SGE does not interfere on the differentiation, maturation and function of murine dendritic cells. However, salivary components of these mosquitoes have a direct effect on lymphocytes. The mechanism of action of SGE involved apoptosis of naïve T cells, while memory cells were more resistant to this activity. A molecule with molecular weight above 400 kDa is likely responsible for this effect. .Taken together, the results generated by this work contribute to the understanding of the biological effects of Ae. aegypti saliva on the host and, consequently, its role on the transmission of diseases.
1160

Autoantibodies and the Type I Interferon System in the Etiopathogenesis of Systemic Lupus Erythematosus

Blomberg, Stina January 2003 (has links)
<p>In sera remitted for anti-nuclear antibody (ANA) analysis, the supplement of a sensitive anti-SSA/Ro ELISA to the conventional ANA screening by immunofluorescence (IF) revealed that one fourth of the individuals with IF-ANA negative, but SSA/Ro ELISA positive sera, had systemic lupus erythematosus (SLE) or cutaneous LE. Consequently, adding a sensitive anti-SSA/Ro ELISA to the ANA screening is valuable for the serological detection of ANA negative SLE/LE patients.</p><p>SLE patients often have measurable interferon-alpha (IFN-α) levels in serum, and IFN-α treatment of patients with non-autoimmune diseases can induce SLE. Thus, the type I IFN system seems to be important in SLE and was therefore investigated. Initially, a decreased IFN-α producing capacity, due to a 70-fold reduction in the number of circulating natural IFN-α producing cells (NIPC), was noted in peripheral blood mononuclear cells (PBMC) from SLE patients. SLE-sera contained an endogenous IFN-α inducing factor (SLE-IIF), consisting of IgG and DNA in the form of small immune complexes (300-1000 kD). The SLE-IIF selectively activated NIPC and was more common in sera from patients with active disease compared to individuals with inactive disease. IFN-α producing cells could be detected by immunohistochemistry in both lesional and unaffected skin from SLE patients, and IFN-α gene transcription could be verified by in situ hybridisation in some of the skin biopsies. A reduced number of NIPC, detected by expression of the blood dendritic cell antigen (BDCA)-2, was noted among SLE-PBMC. The IFN-α production triggered by SLE-IIF in SLE-PBMC was inhibited by monoclonal antibodies (mAbs) to BDCA-2 and markedly decreased by anti-BDCA-4 mAbs. </p><p>The observations in the present thesis may explain the ongoing IFN-α production in SLE patients, indicate an important role for the activated type I IFN system in the pathogenesis, and suggest that direct targeting of SLE-NIPC may constitute a new therapeutic principle in SLE.</p>

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