Embora a utilização do corticóide oral não seja indicada no tratamento de manutenção na doença pulmonar obstrutiva crônica, identificamos em nosso ambulatório, um grupo de pacientes que fazem uso desta medicação de forma continuada e, nos quais, todas as tentativas anteriores de retirada da medicação, havia resultado em exacerbação dos sintomas. O objetivo deste estudo foi o de analisar os fenômenos inflamatórios associados à tentativa de redução progressiva do corticóide oral nesses doentes. Avaliamos o escarro induzido de 14 pacientes usuários crônicos de corticóide. Após a avaliação basal, realizada enquanto os pacientes faziam uso de sua dose habitual da medicação (V0), procedemos ao aumento da prednisona a 40 mg por dia, por duas semanas (V1). A seguir, reduzimos progressivamente a dose até que ocorresse uma exacerbação (EXAC), quando a dose de 40 mg de prednisona foi re-introduzida por duas semanas (APÓS). Comparamos os resultados deste grupo aos de um grupo de pacientes portadores de DPOC não-usuários de corticóide oral. Esses pacientes foram avaliados na condição basal (V0), quando exacerbaram (EXAC) e após o tratamento com 40 mg de prednisona, por duas semanas (APÓS). As variáveis analisadas no escarro foram: % de neutrófilos, % de eosinófilos, % de macrófagos, número total de células, interleucinas 4, 6 e 8. Constatamos que o grupo corticóide apresentou um aumento significativo na porcentagem de eosinófilos na exacerbação em relação a V0, e uma redução significativa em APÓS, em relação a EXAC. Isto não ocorreu no grupo não-corticóide. Ao compararmos os dois grupos, observamos que a concentração das interleucinas 4, 6 e 8, foi significativamente mais alta no grupo corticóide em V0 e na exacerbação em relação ao grupo não-corticóide. Quando analisamos o comportamento das interleucinas nas avaliações seqüenciais, dentro de cada grupo, observamos que a interleucina 4 tendeu à elevação na exacerbação, no grupo corticóide, sem atingir, entretanto, significância estatística. As interleucinas 6 e 8 aumentaram significativamente no grupo corticóide na visita APÓS. Concluímos que a retirada progressiva de corticóide oral induz a exacerbação em pacientes com DPOC corticóide-dependentes com um processo inflamatório eosinofílico, que tende à reversão após o aumento da dose do corticóide / Although in chronic obstructive lung disease the use of oral corticoid is not indicated in the maintenance treatment, we identified a group of patients that make use of this medication continuously. The objective of this study was to analyze the inflammatory phenomena associated to the attempt of progressive reduction of oral corticoids in these patients. We evaluated induced sputum of 14 patients on long-term use of oral corticoids. After the basal evaluation, accomplished while the patients made use of their habitual dose of the medication (V0), we increased the dose of prednisone to 40 mg daily for two weeks (V1). To proceed we reduced the dose progressively until an exacerbation occurred (EXAC), when the dose of prednisone 40 mg daily was reintroduced for two weeks (AFTER). We compared the results to a group of patients with COPD not on use of oral corticoids, that were appraised in the basal condition (V0), when they exacerbated (EXAC) and after the treatment with prednisone 40 mg daily for two weeks (AFTER). The variables analyzed in the sputum were:, % of neutrophils, % of eosinophils, % of macrophages, total number of cells, interleukins 4, 6 and 8. We verified that the corticoid group presented a significant increase in the percentage of eosinophils at the exacerbation in relation to V0, and a significant reduction in AFTER in relation to EXAC. This didn\'t happen in the non corticoid group. When we compared the two groups we observed that the concentration of the interleukins was significantly higher in corticoid group in V0 and at the exacerbation in relation to the non corticoid group. When we analyzed the behavior of the interleukins along the evaluations in each group we observed that interleukin 4 tended to an elevation at the exacerbation in the corticoid group, without reaching statistical significance. Interleukins 6 and 8 increased significantly in the corticoid group in the visit AFTER. We concluded that the progressive reduction of oral corticoid induces exacerbation in patients with COPD on long-term use of prednisone with an eosinophilic inflammatory process that tends to reverse after the increase of the dose of the corticoid

Introdução: A rinite alérgica (RA) e a rinossinusite crônica (RSC) são doenças inflamatórias nasais com prevalência alta e crescente. Estima-se que 15,5% dos norte-americanos tenham RSC, e estudo recente encontrou prevalência de 5,51% na cidade de São Paulo, enquanto a RA acomete entre 10 e 20% da população mundial. Apesar de terem mecanismos fisiopatológicos distintos, em ambas, há recrutamento de células de defesa, principalmente linfócitos T, e produção de citocinas inflamatórias. Esses mediadores variam não apenas entre as doenças, mas também entre as populações acometidas, e seu conhecimento é importante para o diagnóstico correto e direcionamento da terapia escolhida. Objetivos: Mapear os mediadores inflamatórios presentes no lavado nasal e no condensado do ar exalado na RSC e na RA, avaliando possíveis biomarcadores da doença, e analisar o endotipo inflamatório dos pacientes estudados. Além disso, avaliar a qualidade de vida, o nível de obstrução nasal, a qualidade do sono dos pacientes afetados, o transporte mucociliar e coletar material para análise de pH, contagem de células totais e seu diferencial. Pacientes e métodos: Estudo exploratório prospectivo em corte transversal, sendo os pacientes divididos em quatro grupos: 1) Grupocontrole com pacientes sem queixas; 2) Pacientes com RA com prick test positivo; 3) Pacientes com RSC com polipose; e 4) Pacientes com RSC sem polipose. Todos os pacientes responderam a quatro questionários: 20-Item Sino-Nasal Outcome Test (SNOT-20p), Nasal Obstruction Symptom Evaluation (NOSE), o Índice de Qualidade do Sono de Pittsburgh (Pittsburgh Sleep Quality Index - PSQI-BR) e o questionário para triagem e diagnóstico da asma da European Community Respiratory Health Survey (ECRHS). Foi realizado exame físico, incluindo endoscopia nasal (escore de Lund- Kennedy modificado) e, nos pacientes com RSC, avaliação da tomografia computadorizada (TC) de face (escore de Lund-Mackay). Foi também avaliado o transporte mucociliar por meio do teste da sacarina. Coletou-se o condensado do ar exalado para análise do pH e lavado nasal para avaliação do pH, da presença de citocinas e da celularidade (total e diferencial). Foi avaliada a presença de IL-4, IL-5, IL-8, IL-17A, IL-22, TNF-Alfa e IFN-Gama no lavado nasal e IL-5, IL-17A, IL-22 e IFN-Gama no condensado do ar exalado. Resultados: Os pacientes com RSC apresentaram escores significativamente piores nos questionários de obstrução nasal (NOSE, p < 0,01) e qualidade de vida (SNOT-20p, p < 0,01) quando comparados aos controles, e tanto os pacientes com RSC quanto com RA apresentaram pior qualidade do sono (PSQI-BR, p < 0,01). O escore de extensão de Lund- Mackay foi mais elevado nos pacientes com RSC com polipose (p < 0,02). O teste da sacarina apresentou tempo mais prolongado no grupo RSC com polipose (p < 0,01). O pH do condensado do ar exalado não diferiu entre os grupos. O grupo RSC com polipose apresentou tanto diferença do pH (p < 0,01) quanto da contagem de células totais do lavado nasal (p < 0,01) quando comparado ao grupo-controle, porém sem diferença na contagem diferencial. IFN? do condensado foi mais elevado no grupo RA em comparação ao grupo C (p=0,05), enquanto IL-5 foi mais alto no grupo RSC com polipose quando comparado ao grupo RSC sem polipose (p=0,02). Os pacientes foram, então, divididos em endotipos, segundo os grupos descritos por Tomassen et al., sendo que endotipos são os subtipos da doença definidos funcionalmente e patologicamente por mecanismos moleculares distintos. Conclusão: Pacientes com RSC apresentaram escores piores nos questionários de qualidade de vida (SNOT-20p e NOSE), o que, em parte, poderia ser atribuído à pior qualidade do sono apresentada tanto por estes pacientes quanto pelos portadores de RA. O teste da sacarina evidenciou pior transporte mucociliar nos pacientes com RSC com polipose. Não houve diferença do pH do condensado do ar exalado, sugerindo que, apesar de interessante na avaliação das vias aéreas inferiores, este pode não ser um bom teste para análise das vias aéreas superiores. Foram encontradas alterações significantes tanto do pH quanto da contagem de células totais do lavado nasal do grupo com RSC com polipose, sem, no entanto, haver diferença na contagem diferencial. Dos 17 pacientes com RSC com perfil completo de citocinas, 12 se encaixam em endotipos já descritos, sendo que, dos cinco restantes, dois apresentam o mesmo perfil, podendo indicar um novo subgrupo / Introduction: Allergic rhinitis (AR) and chronic rhinosinusitis (CRS) are nasal inflammatory diseases with high and increasing prevalence. It is estimated that 15.5% of Americans have CRS, and a recent study found a prevalence of 5.51% in the city of São Paulo, while AR affects between 10 and 20% of the world population. Although they have distinct pathophysiological mechanisms, in both there is recruitment of defense cells, mainly T lymphocytes, and production of inflammatory cytokines. These mediators vary not only between diseases but also among affected populations, and their knowledge is important for the correct diagnosis and targeting of the therapy chosen. Objectives: To map the inflammatory mediators present in the nasal wash and the exhaled breath condensate in the CRS and AR, evaluating possible biomarkers of this diseases, and to analyze the inflammatory endotype of the patients studied. In addition, assess quality of life, level of nasal obstruction, sleep quality of affected patients, mucociliary transport and collect samples for pH analysis, total cell count and its differential. Patients and Methods: Prospective cross-sectional exploratory study, divided into four groups: 1) Control group with patients without complaints 2) Patients with AR with prick test positive 3) Patients with CRS with polyps 4) Patients with CRS without polyps. All patients responded to four questionnaires: 20-Item Sino-Nasal Outcome Test (SNOT-20p), Nasal Obstruction Symptom Evaluation (NOSE), Pittsburgh Sleep Quality Index (PSQI-BR) and European Community Respiratory Health Survey (ECRHS) questionnaire for screening and diagnosis of asthma. A physical examination was performed, including nasal endoscopy (modified Lund-Kennedy score) and, in patients with CRS, a computerized tomography (Lund-Mackay score) evaluation. The mucociliary transport was also evaluated through the saccharin test. The exhaled breath condensate was collected for pH analysis and the nasal wash for evaluation of pH, cytokines and cellularity (total and differential). The presence of IL-4, IL-5, IL-17, IL-17A, IL-22, TNF-Alfa and IFN-Gama in the nasal wash and IL-5, IL-17A, IL-22 and IFN-Gama in the exhaled breath condensate. Results: Patients with CRS had significantly worse scores in the nasal obstruction questionnaire (NOSE, p < 0.01) and quality of life questionnaire (SNOT-20p, p < 0.01) when compared to controls, and both patients with CRS and AR presented worse sleep quality (PSQI-BR, p < 0.01). The Lund-Mackay extension score was higher in patients with CRS with polyps (p < 0.02). The saccharin test showed longer time in the CSR group with polyps (p < 0.01). The pH of the exhaled breath condensate did not differ between groups. The CRS with polyps group presented both pH difference (p < 0.01) and higher total nasal wash cell count (p < 0.01) when compared to the control group, but with no difference in the differential count (p = 0.05), while IL-5 was higher in the CRS group with polyps when compared to the RSC without polyps group (p = 0.02). Patients were then divided into endotypes according to the groups described by Tomassen et al, Endotypes are the subtypes of the disease defined functionally and pathologically by distinct molecular mechanisms. Conclusions: Patients with CRS presented worse scores on quality of life questionnaires (SNOT-20p and NOSE), which could be attributed in part to the poorer quality of sleep presented by both patients with CRS and AR. The saccharin test evidenced worse mucociliary transport in patients with CRS with polyps when compared with control group. There was no difference in the pH of the exhaled breath condensate, suggesting that, although interesting in the evaluation of the lower airways, this may not be a good test for analyzing the upper airways. Significant alterations were found in both pH and total nasal wash cell count in the CSR group with polyposis, but there was no difference in the differential count. Of the 17 patients with CRS with complete cytokine profile, 12 fit into already described endotypes, and of the remaining five, two have the same profile, which may indicate a new subgroup

Embora a utilização do corticóide oral não seja indicada no tratamento de manutenção na doença pulmonar obstrutiva crônica, identificamos em nosso ambulatório, um grupo de pacientes que fazem uso desta medicação de forma continuada e, nos quais, todas as tentativas anteriores de retirada da medicação, havia resultado em exacerbação dos sintomas. O objetivo deste estudo foi o de analisar os fenômenos inflamatórios associados à tentativa de redução progressiva do corticóide oral nesses doentes. Avaliamos o escarro induzido de 14 pacientes usuários crônicos de corticóide. Após a avaliação basal, realizada enquanto os pacientes faziam uso de sua dose habitual da medicação (V0), procedemos ao aumento da prednisona a 40 mg por dia, por duas semanas (V1). A seguir, reduzimos progressivamente a dose até que ocorresse uma exacerbação (EXAC), quando a dose de 40 mg de prednisona foi re-introduzida por duas semanas (APÓS). Comparamos os resultados deste grupo aos de um grupo de pacientes portadores de DPOC não-usuários de corticóide oral. Esses pacientes foram avaliados na condição basal (V0), quando exacerbaram (EXAC) e após o tratamento com 40 mg de prednisona, por duas semanas (APÓS). As variáveis analisadas no escarro foram: % de neutrófilos, % de eosinófilos, % de macrófagos, número total de células, interleucinas 4, 6 e 8. Constatamos que o grupo corticóide apresentou um aumento significativo na porcentagem de eosinófilos na exacerbação em relação a V0, e uma redução significativa em APÓS, em relação a EXAC. Isto não ocorreu no grupo não-corticóide. Ao compararmos os dois grupos, observamos que a concentração das interleucinas 4, 6 e 8, foi significativamente mais alta no grupo corticóide em V0 e na exacerbação em relação ao grupo não-corticóide. Quando analisamos o comportamento das interleucinas nas avaliações seqüenciais, dentro de cada grupo, observamos que a interleucina 4 tendeu à elevação na exacerbação, no grupo corticóide, sem atingir, entretanto, significância estatística. As interleucinas 6 e 8 aumentaram significativamente no grupo corticóide na visita APÓS. Concluímos que a retirada progressiva de corticóide oral induz a exacerbação em pacientes com DPOC corticóide-dependentes com um processo inflamatório eosinofílico, que tende à reversão após o aumento da dose do corticóide / Although in chronic obstructive lung disease the use of oral corticoid is not indicated in the maintenance treatment, we identified a group of patients that make use of this medication continuously. The objective of this study was to analyze the inflammatory phenomena associated to the attempt of progressive reduction of oral corticoids in these patients. We evaluated induced sputum of 14 patients on long-term use of oral corticoids. After the basal evaluation, accomplished while the patients made use of their habitual dose of the medication (V0), we increased the dose of prednisone to 40 mg daily for two weeks (V1). To proceed we reduced the dose progressively until an exacerbation occurred (EXAC), when the dose of prednisone 40 mg daily was reintroduced for two weeks (AFTER). We compared the results to a group of patients with COPD not on use of oral corticoids, that were appraised in the basal condition (V0), when they exacerbated (EXAC) and after the treatment with prednisone 40 mg daily for two weeks (AFTER). The variables analyzed in the sputum were:, % of neutrophils, % of eosinophils, % of macrophages, total number of cells, interleukins 4, 6 and 8. We verified that the corticoid group presented a significant increase in the percentage of eosinophils at the exacerbation in relation to V0, and a significant reduction in AFTER in relation to EXAC. This didn\'t happen in the non corticoid group. When we compared the two groups we observed that the concentration of the interleukins was significantly higher in corticoid group in V0 and at the exacerbation in relation to the non corticoid group. When we analyzed the behavior of the interleukins along the evaluations in each group we observed that interleukin 4 tended to an elevation at the exacerbation in the corticoid group, without reaching statistical significance. Interleukins 6 and 8 increased significantly in the corticoid group in the visit AFTER. We concluded that the progressive reduction of oral corticoid induces exacerbation in patients with COPD on long-term use of prednisone with an eosinophilic inflammatory process that tends to reverse after the increase of the dose of the corticoid

Les protéines étant au coeur d’un grand nombre de processus biologiques, elles sont des cibles thérapeutiques largement convoitées. Les foldamères, notamment les oligoamides aromatiques, présentent une structure bien définie, prévisible, stable en solution et à l’état solide. Ajouté à cela, leur taille moyenne en fait de bons candidats pour la reconnaissance de surfaces de protéines, grâce à leurs chaînes latérales protéinogènes. Cette thèse présente les différentes étapes de leur conception, de la synthèse de la brique constitutive à l’obtention d’un foldamère fonctionnalisé grâce à la synthèse en phase supportée. La stratégie d’investigation des interactions entre un foldamère et une protéine est détaillée. L’originalité réside dans le fait que le foldamère est ancré directement à la protéine et le dichroïsme circulaire sert de méthode de screening. L’analyse structurale des hits permet de générer de nouveaux foldamères dans le but d’améliorer les interactions avec la protéine : c’est une stratégie itérative. Cette approche est appliquée premièrement à l’anhydrase carbonique humaine II, protéine modèle qui sert de preuve de principe pour cette approche ; puis à des protéines d’intérêt thérapeutique plus important : l’interleukine 4 et la cyclophiline A. Enfin, une étude concernant l’introduction de flexibilité au sein de foldamères de quinolines est présentée. / Since proteins are at the basis of many biological processes, they are widely studied as therapeutic targets. Aromatic oligoamide foldamers have a very well defined structure, predictable and stable both in solution and solid state. Because of their medium size, they appear as potent candidates for protein surface recognition thanks to their proteinogenic side chains. This manuscript presents the different steps of their design, from the scaffold’s synthesis to obtaining a functionalized foldamer, thanks to solid phase synthesis. The strategy to investigate protein/foldamer interactions will be detailed. Its originality lies in the fact that the foldamer is anchored to the protein. Circular dichroism has been used as a screening method to detect foldamer/protein interactions. Structural analysis of the hits will allow the design of new foldamers with the objective of enhancing foldamer/protein interactions: it is an iterative strategy. This approach has been applied firstly to human carbonic anhydrase II (HCA). This protein is used as a model system and proof of concept before moving to more therapeutically relevant proteins; interleukin 4 and cyclophilin A. Finally, a study on introducing flexibility in quinoline foldamers is presented.

Les lymphocytes B jouent un rôle central dans l’immunité humorale par leur capacité à présenter des antigènes aux lymphocytes T, à sécréter des cytokines et à se différencier en plasmocytes produisant des anticorps. Ces fonctions peuvent être induites par leur stimulation in vitro. Par leur aptitude à présenter des antigènes indépendamment de la spécificité du récepteur des lymphocytes B (BCR), les lymphocytes B peuvent être utilisés comme cellules présentatrices d’antigènes (antigen-presenting cells, APC) afin d’induire la réponse cellulaire des lymphocytes T CD8+ cytotoxiques spécifiques. L’immunité cellulaire est cruciale pour prévenir les infections contre certains virus et en immunothérapie du cancer. L’objectif général de ces travaux est d’étudier la biologie des lymphocytes B. Plus particulièrement, nous souhaitons comprendre et améliorer leur fonction de présentation d’antigène afin d’utiliser les lymphocytes B comme source alternative d’APC. Dans la première partie de ces travaux, notre attention s’est portée sur la compréhension du mécanisme de présentation croisée par le complexe majeur d’histocompatibilité de classe I (CMH-I) par lequel un épitope de la protéine gp100 du mélanome, inséré dans une nanoparticule pseudo-virale (VLP) composée de la protéine de surface du virus de la mosaïque de la papaye (PapMV), est présenté par les lymphocytes B. Cette VLP est une plateforme vaccinale capable de stimuler le système immunitaire sans l’aide d’adjuvant et facilite la présentation croisée de l’épitope inséré, de façon indépendante de l’activité du protéasome. Les résultats obtenus démontrent que l’apprêtement de l’épitope inséré dans la nanoparticule s’effectue selon une voie de présentation croisée vacuolaire qui dépend de l’activité de la cathepsine S, de l’acidification des lysosomes et requiert l’induction de l’autophagie. Ainsi, nous avons défini plus précisément le mécanisme de présentation croisée par lequel les lymphocytes B apprêtent et présentent un épitope inséré dans la VLP de PapMV. Par la suite, nous avons cherché à améliorer le protocole d’activation in vitro permettant d’amplifier et d’induire les fonctions de présentation d’antigènes des lymphocytes B, dans le but d’utiliser ces cellules pour activer les réponses cellulaires des lymphocytes T CD8+ cytotoxiques. Les stimulations in vitro des lymphocytes B par le CD40 ligand (CD40L) et l’interleukine (IL)-21 ou la combinaison de l’IL-4 et l’IL-21 au lieu de l’activation standard avec le CD40L et l’IL-4 ont été évaluées. Nos résultats ont approfondi nos connaissances de la biologie des lymphocytes B. Nous avons démontré que la stimulation des lymphocytes B avec le CD40L et l’IL-21 augmente leur prolifération, mais mène à leur différenciation en plasmocytes sécrétant des anticorps. Au contraire, la stimulation avec le CD40L et l’IL-4 induit efficacement leur fonction de présentation d’antigènes. La stimulation des lymphocytes B avec le CD40L et la combinaison de l’IL-4 et de l’IL-21 augmente leur prolifération, mène seulement faiblement à leur différenciation en cellules sécrétrices d’anticorps, mais induit efficacement leur fonction de présentation d’antigènes. Nous avons démontré pour la première fois que cette méthode permet de générer des APC puissantes capables d’induire la réponse des lymphocytes T CD8+ cytotoxiques in vitro. Nos résultats nous permettent de postuler que ces cellules pourraient être capables de mener à une réponse cellulaire in vivo. En tant qu’APC efficaces, les lymphocytes B pourraient être utilisés dans une stratégie vaccinale ou être employés comme APC afin d’améliorer les traitements d’immunothérapie du cancer par transfert adoptif de lymphocytes T. Ainsi, les travaux présentés dans cette thèse ont porté tant sur la compréhension des mécanismes de présentation croisée d’un épitope inséré dans la VLP de PapMV par les lymphocytes B, que sur l’amélioration de la méthode permettant d’induire leur fonction de présentation d’antigènes pour activer les lymphocytes T CD8+ cytotoxiques. Ces travaux de recherche fondamentale ont permis de contribuer à des avancées sur les connaissances de la biologie des lymphocytes B. Ils offrent de nouvelles pistes de réflexion quant aux utilisations biotechnologiques des lymphocytes B comme source alternative d’APC pour des applications de recherche fondamentale et clinique telles que la vaccination et les traitements d’immunothérapie du cancer. / B lymphocytes are central to humoral immunity due to their ability to present antigens to T cells, secrete cytokines and to differentiate into antibody-producing plasma cells. These functions can be induced by their in vitro stimulation. Being able to present antigens independently of the specificity of their B cell receptor (BCR), B cells can be used as antigen-presenting cells (APC) to induce specific cytotoxic CD8+ T cell cellular responses. Cellular immunity is crucial to prevent infections against viruses and in cancer immunotherapy. The main aim of this thesis is to study B cell biology. Specifically, we aim to deepen our understanding of their antigen presentation function and improve this function to use B cells as an alternative source of APC. First, we focused on deciphering the class I major histocompatibility complex (MHC-I) cross-presentation mechanism by which an epitope from gp100 melanoma protein, inserted in a virus-like particle (VLP) made of the coat protein of the papaya mosaic virus (PapMV), is presented by B cells. This VLP is a vaccine platform able to stimulate the immune system with no adjuvant and mediate a proteasome independent cross-presentation of the inserted epitope. Our results show that the inserted epitope is processed through a vacuolar pathway dependent on cathepsin S activity, lysosome acidification and requires the induction of autophagy. Thus, we provide a more detailed characterization of the mechanism used by B cells to process and cross-present an epitope inserted in PapMV VLP. Secondly, we aimed to improve the in vitro activation protocol used to expand B cells and induce their antigen presentation functions to use these cells to trigger cytotoxic CD8+ T cell cellular responses. We evaluated the in vitro stimulation of B cells with CD40 ligand (CD40L) and interleukin (IL)-21 or the combination of IL-4 and IL-21 instead of the standard activation method based on CD40L and IL-4. Our results deepen our knowledge of B cell biology. We showed that stimulating B cells with CD40L and IL-21 increases their proliferation but leads to their differentiation in antibody-producing plasma cells. In comparison, the stimulation with CD40L and IL-4 efficiently induces their antigen presentation function. The stimulation of B lymphocytes with CD40L and the combination of IL-4 and IL-21 increases their proliferation, weakly leads to their differentiation in antibody-secreting cells but is very efficient in inducing their antigen presentation function. We show for the first time that this method can generate potent APC able to induce cytotoxic CD8+ T cell responses in vitro. Our results allow us to hypothesize that these cells could be capable of triggering cellular immunity in vivo. As efficient APC, B cells could be used in a vaccination strategy or be employed as APC to improve cancer immunotherapy treatments such as adoptive cell transfer of T lymphocytes. Thus, the work presented in this thesis provides a deeper understanding of the antigen cross-presentation pathway by which B cells process and present an epitope inserted in PapMV VLP. It also reports an improved method to induce antigen presentation function of B cells to stimulate cytotoxic CD8+ T cells. This research work constitutes a leap forward in fundamental B cell research by increasing our knowledge of B cell biology. It also brings new opportunities regarding biotechnological uses of B cells as an alternative source of APC for fundamental and clinical applications such as vaccination and cancer immunotherapy treatments.

Glycosphingolipids (GSLs), composed of a polar saccharide head and a lipophilic ceramide tail, are ubiquitous components of the plasma membrane of eukaryotic cells. They serve in many regulatory capacities and have antigenic properties towards natural killer T (NKT) cells of the innate immune system. Critical to the recognition of glycosylceramides by NKT cells are antigen presenting cells (APC), such as dendritic cells, which are responsible for binding, processing, and delivery of ligands to these lymphocytes. This event is mediated by CD1d, a major histocompatibility complex-like protein expressed on the surface of APCs, which binds GSL antigens by the ceramide moiety and presents the polar group to the T cell receptors of CD1d-restricted cells. The subsequent immune response involves NKT cell proliferation and emission of numerous cytokines, such as interferon-gamma (IFN-gamma) and interleukin-4 (IL-4), resulting in the stimulation of the innate and adaptive immune systems through maturation of APCs, activation of T cells, and secretion of antibodies by B cells. To understand the structure-activity relationship between GSLs and NKT cell activity and the requirements for intracellular processing of antigens, analogs of the model compound alphaGalCer (KRN-7000) have been synthesized. These include fluorophore-appended 6”-amino-α-galactosylceramides and N-alkenoyl GSLs, such as PBS-57, a potent alphaGalCer surrogate useful in NKT cell stimulation studies. A nonantigenic beta-C-galactosylceramide has also been prepared as an inhibitor of these innate lymphocytes. To probe the potential for using NKT cells to bias the immune system between the proinflammatory TH1 response or the immunomodulatory TH2 mode, versions of alphaGalCer with shortened ceramides have been created. One of these truncated analogs, PBS-25, has successfully been cocrystallized with CD1d and the binary complex structure solved by X-ray crystallography. Synthetic glycosphingolipids derived from Novosphingobium capsulatum and Sphingomonas paucimobilis have also been made. In assays with classical Valpha14i/Valpha24i NKT cell lines, these Gram-negative bacterial antigens were recognized directly and specifically by host immune systems through CD1d-restriction, unlike GSL-deficient microbes (e.g., Salmonella typhimurium). A search for other GSL-bearing alpha-proteobacteria led to the discovery of another natural glycosphingolipid, an N-alkenoylphytosphingoid-alpha-galactoside, isolated from the outer membrane of Ehrlichia muris.

Thesis (Ph. D.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).