Made available in DSpace on 2016-01-26T18:55:27Z (GMT). No. of bitstreams: 1 Dissertacao Sandro.pdf: 259492 bytes, checksum: 9e24465090764a22ac75d827ad8af255 (MD5) Previous issue date: 2008-08-27 / The effect of a probiotic on the immune response of cattle immunized with one dose of rabies vaccine was evaluated in this study. The Nelore bovines (N=75) were divided randomly into 5 groups: four groups fed with a diet supplemented with the 2, 3, 4 and 8 g the probiotic (Proenzime®)/bovine/day, groups G2, G3, G4 and G8, respectively, for 60 days. The 5th group was used as control. All the animals were immunized with a single dose of rabies vaccine on the first day of the experiment (day 0). The antibody titers were measured on days 0, 30 and 60 by RFFIT test. The results show the significant interaction was found between the probiotic level and vaccination time. There was also a significant difference among rabies titers in groups Gc, G2, G3, G4 and G8 on both days 30 and 60. In group G4, titers of rabies antibody in cattle decreased significantly on day 60. A significant difference (p<0.05) between the frequency of immunized animals in the control group and the other treatments was found on both days 30 and 60. On day 60, the control group did not differ from G2. However, no significant difference (p<0.05) was found among the treatments which were supplemented with probiotic. In addition, no significant difference (p<0.05) between the frequency of immunized animals on days 30 and 60 was found in control (Gc) or any other treatment (G2, G3, G4 or G8). In conclusion, the probiotic (Proenzime®) increase the humoral immune response of bovine immunized with rabies vaccine. / Foi avaliado o efeito do probiótico sobre a resposta imune de bovinos imunizados com uma dose de vacina anti-rábica. Utilizaram-se bovinos Nelore (N=75) divididos randomicamente em 5 grupos: quatro grupos foram suplementados com 2, 3, 4 e 8 g probiótico (Proenzime®)/bovino/dia, grupos G2, G3, G4 e G8, respectivamente, por 60 dias. O 5º grupo foi controle. Todos os animais foram imunizados com uma dose de vacina anti-rábica no dia zero do experimento. Os títulos de anticorpos anti-rábicos foram mensurados nos dias 0, 30, 60 por meio do teste de RFFIT. Os resultados mostraram interação significativa entre concentração de probiótico e tempo de vacinação. Também teve aumento significativo nos títulos de anticorpos anti-rábicos nos grupos Gc, G2, G3, G4 e G8 nos dias 30 e 60. No grupo G4 os títulos de anticorpos anti-rábicos reduziram significativamente no dia 60. Houve diferença significativa (p<0,05) entre a freqüência de animais imunizados entre os grupos controle e tratados nos dias 30 e 60. No dia 60, o grupo controle não diferiu do G2. Além disso, não houve diferença significativa (p<0,05) na freqüência de animais nos dias 30 e 60, no grupo controle ou nos grupos tratados (G2, G3, G4 e G8). Conclui-se que o probiótico (Proenzime®) aumentou a resposta imune humoral em bovinos imunizados com vacina anti-rábica.

Made available in DSpace on 2016-01-26T18:55:38Z (GMT). No. of bitstreams: 1 Lundia Bin.pdf: 419626 bytes, checksum: 784b66188ef611a6dd9abf0fdddd231f (MD5) Previous issue date: 2013-08-23 / Toxocariasis is an important zoonosis mainly transmitted by ingestion of embryonated T. canis eggs, a parasite of dogs, present in soil. The nematode larvae can migrate by a variety of organs e may cause disturbances, including respiratory, hepatic, neurological, cardiac and ophthalmic problems. Diagnostic of toxocariasis is based on detection of anti-Toxocara antibodies, particularly IgG, by ELISA. Avidity of IgG has been employed in order to evaluate the phase of infection of a disease. However, experimental studies regard to toxocariasis are scarce in literature. This study aimed to evaluate the Toxocara canis-IgG avidity in experimentally infected rabbits, before and after lactation, and of their offsprings. Seventeen nullipar white New Zealand female rabbits were distributed in two groups. In experimentally infected group, 12 animals were inoculated by oral route with 1,000 T. canis embryonated eggs, whereas five animals were uninfected (control group). Blood samples collections were performed on +7, +14, +21 and +28 days post-infection (dpi) and on the first day following the weaning (60 dpi) in order to obtaining serum for ELISA analysis. ELISA indirect test was run in order to obtain the anti- T. canis antibody reactivity index (RI) as well as the avidity index (AI). Seroconversion was observed on 14 dpi, and all the evaluated animals showed a high AI, excepting one animal (on 14 dpi). After the weaning period, all the studied rabbit showed seroconversion. All the studied bunnies were considered positive for ELISA and showed a high AI. Nevertheless, both RI and AI of mothers were significantly higher than their offspring. According to the results, it was possible to demonstrate the vertical transmission of T. canis larvae. In addition, the negative correlation between the RI obtained from the rabbits and the bunnies pointed out the possibility of passive protection due to the maternal transfer of antibodies. / A toxocaríase é uma importante zoonose transmitida principalmente pela ingestão de ovos embrionados de T.canis, um parasito de cães, presente no solo. A larva do nematódeo pode migrar por vários órgãos do corpo e ocasionar distúrbios, como problemas respiratórios, hepáticos, neurológicos, cardíacos e oftálmicos. O diagnóstico é realizado principalmente com a detecção de anticorpos, em especial de Imunoglobulinas da classe G (IgG), pela técnica de ELISA. A avidez de IgG tem sido utilizada para avaliar a fase de infecção de uma doença. No caso da toxocaríase, estudos experimentais são escassos na literatura. O objetivo do estudo foi o de avaliar a avidez de anticorpos anti-Toxocara canis em coelhas infectadas experimentalmente, antes e após lactação, e de suas progênies. Foram utilizadas 17 coelhas da linhagem Nova Zelândia, brancas, nulíparas, distribuídas em dois grupos. No grupo experimental, doze coelhas foram infectadas, oralmente, com 1.000 ovos larvados de T. canis. O segundo grupo, constituído por cinco coelhas serviu como controle. Nos dias 7, 14, 21 e 28 pós-infecção (DPI) e no primeiro dia após o desmame (60 DPI), foram coletadas amostras de soro para análise. O teste de ELISA indireto foi realizado para avaliar a o índice de reatividade (IR) de anticorpos IgG anti-T. canis e para cálculo do índice de avidez (IA). A soroconversão nos animais ocorreu a partir do 140 DPI. Com exceção de um animal (aos 14 DPI), todos os IA foram classificados como de alta avidez. Após lactação, (60 DPI), todos os animais foram considerados como ELISA positivo. Em relação aos filhotes todos os animais foram sororreagentes e apresentaram alto IA. Entretanto, tanto o IR quanto o IA das fêmeas foram significativamente maiores que da sua progênie. Os resultados demonstraram a transmissão vertical de larvas. A correlação negativa entre os valores da IR das coelhas e de seus filhotes sugere a possibilidade de proteção passiva pela transferência de anticorpos maternais.

Made available in DSpace on 2016-07-18T17:53:05Z (GMT). No. of bitstreams: 1 Dissertacao Sandro.pdf: 259492 bytes, checksum: 9e24465090764a22ac75d827ad8af255 (MD5) Previous issue date: 2008-08-27 / The effect of a probiotic on the immune response of cattle immunized with one dose of rabies vaccine was evaluated in this study. The Nelore bovines (N=75) were divided randomly into 5 groups: four groups fed with a diet supplemented with the 2, 3, 4 and 8 g the probiotic (Proenzime®)/bovine/day, groups G2, G3, G4 and G8, respectively, for 60 days. The 5th group was used as control. All the animals were immunized with a single dose of rabies vaccine on the first day of the experiment (day 0). The antibody titers were measured on days 0, 30 and 60 by RFFIT test. The results show the significant interaction was found between the probiotic level and vaccination time. There was also a significant difference among rabies titers in groups Gc, G2, G3, G4 and G8 on both days 30 and 60. In group G4, titers of rabies antibody in cattle decreased significantly on day 60. A significant difference (p<0.05) between the frequency of immunized animals in the control group and the other treatments was found on both days 30 and 60. On day 60, the control group did not differ from G2. However, no significant difference (p<0.05) was found among the treatments which were supplemented with probiotic. In addition, no significant difference (p<0.05) between the frequency of immunized animals on days 30 and 60 was found in control (Gc) or any other treatment (G2, G3, G4 or G8). In conclusion, the probiotic (Proenzime®) increase the humoral immune response of bovine immunized with rabies vaccine. / Foi avaliado o efeito do probiótico sobre a resposta imune de bovinos imunizados com uma dose de vacina anti-rábica. Utilizaram-se bovinos Nelore (N=75) divididos randomicamente em 5 grupos: quatro grupos foram suplementados com 2, 3, 4 e 8 g probiótico (Proenzime®)/bovino/dia, grupos G2, G3, G4 e G8, respectivamente, por 60 dias. O 5º grupo foi controle. Todos os animais foram imunizados com uma dose de vacina anti-rábica no dia zero do experimento. Os títulos de anticorpos anti-rábicos foram mensurados nos dias 0, 30, 60 por meio do teste de RFFIT. Os resultados mostraram interação significativa entre concentração de probiótico e tempo de vacinação. Também teve aumento significativo nos títulos de anticorpos anti-rábicos nos grupos Gc, G2, G3, G4 e G8 nos dias 30 e 60. No grupo G4 os títulos de anticorpos anti-rábicos reduziram significativamente no dia 60. Houve diferença significativa (p<0,05) entre a freqüência de animais imunizados entre os grupos controle e tratados nos dias 30 e 60. No dia 60, o grupo controle não diferiu do G2. Além disso, não houve diferença significativa (p<0,05) na freqüência de animais nos dias 30 e 60, no grupo controle ou nos grupos tratados (G2, G3, G4 e G8). Conclui-se que o probiótico (Proenzime®) aumentou a resposta imune humoral em bovinos imunizados com vacina anti-rábica.

Made available in DSpace on 2016-07-18T17:53:12Z (GMT). No. of bitstreams: 1 Lundia Bin.pdf: 419626 bytes, checksum: 784b66188ef611a6dd9abf0fdddd231f (MD5) Previous issue date: 2013-08-23 / Toxocariasis is an important zoonosis mainly transmitted by ingestion of embryonated T. canis eggs, a parasite of dogs, present in soil. The nematode larvae can migrate by a variety of organs e may cause disturbances, including respiratory, hepatic, neurological, cardiac and ophthalmic problems. Diagnostic of toxocariasis is based on detection of anti-Toxocara antibodies, particularly IgG, by ELISA. Avidity of IgG has been employed in order to evaluate the phase of infection of a disease. However, experimental studies regard to toxocariasis are scarce in literature. This study aimed to evaluate the Toxocara canis-IgG avidity in experimentally infected rabbits, before and after lactation, and of their offsprings. Seventeen nullipar white New Zealand female rabbits were distributed in two groups. In experimentally infected group, 12 animals were inoculated by oral route with 1,000 T. canis embryonated eggs, whereas five animals were uninfected (control group). Blood samples collections were performed on +7, +14, +21 and +28 days post-infection (dpi) and on the first day following the weaning (60 dpi) in order to obtaining serum for ELISA analysis. ELISA indirect test was run in order to obtain the anti- T. canis antibody reactivity index (RI) as well as the avidity index (AI). Seroconversion was observed on 14 dpi, and all the evaluated animals showed a high AI, excepting one animal (on 14 dpi). After the weaning period, all the studied rabbit showed seroconversion. All the studied bunnies were considered positive for ELISA and showed a high AI. Nevertheless, both RI and AI of mothers were significantly higher than their offspring. According to the results, it was possible to demonstrate the vertical transmission of T. canis larvae. In addition, the negative correlation between the RI obtained from the rabbits and the bunnies pointed out the possibility of passive protection due to the maternal transfer of antibodies. / A toxocaríase é uma importante zoonose transmitida principalmente pela ingestão de ovos embrionados de T.canis, um parasito de cães, presente no solo. A larva do nematódeo pode migrar por vários órgãos do corpo e ocasionar distúrbios, como problemas respiratórios, hepáticos, neurológicos, cardíacos e oftálmicos. O diagnóstico é realizado principalmente com a detecção de anticorpos, em especial de Imunoglobulinas da classe G (IgG), pela técnica de ELISA. A avidez de IgG tem sido utilizada para avaliar a fase de infecção de uma doença. No caso da toxocaríase, estudos experimentais são escassos na literatura. O objetivo do estudo foi o de avaliar a avidez de anticorpos anti-Toxocara canis em coelhas infectadas experimentalmente, antes e após lactação, e de suas progênies. Foram utilizadas 17 coelhas da linhagem Nova Zelândia, brancas, nulíparas, distribuídas em dois grupos. No grupo experimental, doze coelhas foram infectadas, oralmente, com 1.000 ovos larvados de T. canis. O segundo grupo, constituído por cinco coelhas serviu como controle. Nos dias 7, 14, 21 e 28 pós-infecção (DPI) e no primeiro dia após o desmame (60 DPI), foram coletadas amostras de soro para análise. O teste de ELISA indireto foi realizado para avaliar a o índice de reatividade (IR) de anticorpos IgG anti-T. canis e para cálculo do índice de avidez (IA). A soroconversão nos animais ocorreu a partir do 140 DPI. Com exceção de um animal (aos 14 DPI), todos os IA foram classificados como de alta avidez. Após lactação, (60 DPI), todos os animais foram considerados como ELISA positivo. Em relação aos filhotes todos os animais foram sororreagentes e apresentaram alto IA. Entretanto, tanto o IR quanto o IA das fêmeas foram significativamente maiores que da sua progênie. Os resultados demonstraram a transmissão vertical de larvas. A correlação negativa entre os valores da IR das coelhas e de seus filhotes sugere a possibilidade de proteção passiva pela transferência de anticorpos maternais.

Efficient gene transfer has been achieved in several animal models using different vector systems, leading to stable transgene expression. The tight control of this expression is now an important outcome for the field of gene therapy. Such regulation is likely to be required for therapeutic applications and in some instances for safety reasons. For this purpose, several regulatable systems depending on small molecules have been developed. Among these, the tetracycline and the rapamycin dependent systems have been largely used. However, if long-term regulation of the transgene has been obtained in small animal models using these inducible systems, when translational studies were initiated in larger animals, the development of an immune response against proteins involved in transgene regulation were often observed. Such immune response was especially documented when using the TetOn tetracycline regulatable system in nonhuman primates (NHP). Humoral and destructive cellular immune responses against the transactivator involved in this regulation system were documented in a large majority of NHP leading to the complete loss of the transgene regulation and expression. This review will describe the immune responses observed in these different model systems applied for transgene regulation. Focus will be finally given on future directions in which such immune responses might be surmounted, enabling long-term transgene regulation in future clinical developments of gene transfer.

Paracoccidioidomycosis is one of the most prevalent systemic mycosis in Latin America, including Brazil. It is caused by chronic infection with Paracoccidioides brasiliensis, a thermally dimorphic fungus. Calomys callosus, Rengger 1830 (Rodentia, Cricetidae), is a wild rodent found in Central Brazil and has been shown to be susceptible to experimental infection with P. brasiliensis. The objective of this work was to study the clinicopathological aspects of this experimental infection in Calomys. callosus infected with 0.6 x 105 yeast isolated from P. brasiliensis (strain Pb18) and to compare it with two others susceptible animals: A / Sn and B10.A mice. For this, five animals from each group were sacrificed at 7, 15, 30, 60, 90 and 120 days post inoculation (d.p.i.). Samples of the lung, liver and spleen were processed for mycological examination to determine the number of counts of colony forming units (CFU) as well as for histopathological examination using hematoxilyn and eosin (H&E), reticulin Gomori, trichromic (Masson), and Grocott´s stains. Blood samples from each mice were collected from orbital venous plexus and used to detect IgG and IgM specific anti-P. brasiliensis by ELISA. To determine of survival post-infection, others eight animals from each group was used. The mortality rate was higher in C. callosus than A / Sn and B10.A mice, being all deaths occurring up to 118 d.p.i. IgM levels tended to rise in all groups, but in B10.A mice and Calomys callosus groups, the level of IgG was significantly elevated during the all experimental period. Granulomatous lesions were observed in the roots of all animal groups and all granulomas were composed by Langhans giant cells, epithelioid cells, macrophages, lymphocytes, plasma cells, eosinophils, and necrosis. In C. callosus, the development of granulomas in lung was observed with 15 d.p.i. and exhibited extensive necrosis, especially at the end of the experiment. The presence of granulomas in liver was detected with seven d.p.i. in all animals, but the extensive necrosis was observed especially in samples of Calomys callosus. Similar pattern was also observed in spleen samples. In addition, in Calomys callosus the granulomatous lesions were more extensive in lung and spleen than in liver. The assessment of differential deposition of collagen showed that in Calomys callosus and B10.A the lesions were predominantly composed by collagen type III, although in B10.A animals a predominance of collagen type I was observed without, however, exceed the levels observed for collagen type III at the end of the experiment. On the other hand, the levels of collagen were lower in A / Sn mice than Calomys callosus and B10.A. and, apparently, it was not identified in the lung. On the other hand, in this group was observed a tendency to increase the deposition of collagen type I in the liver at the end of experiment. Callomys callosus showed a higher number of CFU in the three organs studied, especially in the lungs. The proportion of viable fungi in liver, lung and spleen was always higher in Calomys callosus than A / Sn and B10.A and tend to increase in liver and lung during the infection progression with the presence of budding fungi. Conclusions: Ours results indicate that the experimental infection by Paracoccidioides brasiliensis (Pb18) was more aggressive and widespread in Calomys callosus than A/Sn and B10, especially in the lung. So, Calomys callosus can be considered as an alternative animal model in studies of paracoccidioidomycosis infection. / Paracoccidioides brasiliensis é um fungo termodimórfico causador da paracoccidioidomicose, a mais prevalente micose profunda e sistêmica da América Latina, ocorrendo principalmente no Brasil. Calomys callosus, Rengger 1830 (Rodentia, Cricetidae), é um roedor selvagem encontrado no Brasil Central, que tem se mostrado susceptível a infecção experimental pelo P. brasiliensis. O objetivo deste trabalho foi estudar aspecctos clínico-patológicos desta infecção em C. callosus inoculados com 0,6 x 105 leveduras de P. brasiliensis, cepa Pb18, comparando-o aos camundongos A/Sn e B10.A. Cinco animais de cada grupo foram sacrificados aos 7, 15, 30, 60, 90 e 120 dias pós inóculo (d.p.i.), e fragmentos dos pulmões, fígado e baço foram processados para exame micológico direto, cultura em Mycosel, contagem de unidades formadoras de colônias (UFC), e para exame histopatológico, através das colorações de hematoxilina e eosina, reticulina de Gomori, tricrômico de Masson, metenamina prata de Gomori-Grocott. Sangue foi coletado do plexo venoso orbital para realização de ELISA e dosagem de IgG e IgM específicos anti-P. brasiliensis. Outro grupo, contendo oito animais de cada espécie, foi usado para observação da sobrevida pós-infecção. A mortalidade foi maior em C. callosus, com todas as mortes ocorrendo até os 118 d.p.i. Os níveis de IgM mostraram tendência a elevação nos três grupos avaliados. Os camundongos B10.A e Calomys callosus mostraram tendência a elevação dos níveis de IgG, observada durante o período experimental. Lesões granulomatosas foram observadas nos órgãos analisados dos três grupos de animais testados, constituídos por células gigantes tipo Langhans, células epitelióides, macrófagos, linfócitos, plasmócitos, eosinófilos e necrose. Nos pulmões os granulomas foram mais precocemente observados em Calomys callosus (15 d.p.i.), evoluindo com maior presença de necrose no final do experimento. O fígado mostrou granulomas já aos sete d.p.i. em todos os animais, sendo mais necrosante em Calomys callosus. Padrão semelhante foi observado também para o baço. Em todos os órgãos analisados, as lesões granulomatosas foram mais extensas em Calomys callosus no pulmão e no baço, ocupando aos 90 d.p.i. respectivamente, 90% e 70% dos parênquimas examinados, sendo mais reduzida no fígado. Em relação à avaliação da deposição diferencial de colágeno, observou-se que as lesões em Calomys callosus e B10.A tiveram predominantemente deposição de colágeno tipo III. No fígado e baço dos animais B10.A identificou-se deposição crescente de colágeno tipo I, sem entretanto superar os níveis observados para o colágeno tipo III, até o final do experimento. Nos camundongos A/Sn os níveis de colágeno depositados foram mais baixos, comparativamente aos outros animais, não sendo aparentemente identificados nas lesões pulmonares, mostrando tendência a aumento de deposição de colágeno tipo I, nos períodos finais do experimento, verificado no fígado. Calomys callosus apresentaram maior número de UFC nos três órgãos estudados, especialmente nos pulmões. As proporções de fungos viáveis identificadas nos diferentes órgãos de Calomys callosus foram maiores que aquelas observadas nos outros animais, tendendo a aumento no fígado e pulmões, com o transcorrer da infecção, ocorrendo o mesmo em relação aos brotamentos fúngicos. Conclusões: A infecção experimental produzida pela inoculação de 0,6 x 105 leveduras de Paracoccidioides brasiliensis, cepa virulenta Pb18 produziu a doença no C. callosus, que sob o ponto de vista clínico-patológico foi mais grave e disseminada do que a observada nos modelos murinos de susceptibilidade e de resistência, sobretudo nos pulmões. Calomys callosus pode ser considerado como modelo animal alternativo no estudo da paracoccidioidomicose infecção. / Doutor em Imunologia e Parasitologia Aplicadas

La réponse humorale aux antigènes (Ag) thymo-indépendants (TI) tels que les polysaccharides (PS) bactériens ne nécessite pas l’intervention des lymphocytes T mais requiert un dialogue entre lymphocytes B et cellules présentatrices d’Ag (APC). La singularité des Ag TI est qu’ils peuvent générer une réponse anticorps (Ac) in vivo en l’absence de signal danger exogène. Nous avons postulé que les PS bactériens sont capables d’induire un état de compétence des APC leur permettant d’exercer leur fonction auxiliaire vis à vis de la différenciation des lymphocytes B induite par les Ag TI. Notre travail a consisté, d’une part, à identifier la nature de l’APC et à documenter l’état de compétence des APC induit par un PS capsulaire d’une souche de pneumocoque (PS3). Nos résultats montrent que les macrophages et les cellules dendritiques peuvent tous deux exercer une fonction auxiliaire vis-à-vis de la réponse Ac aux Ag TI via la sécrétion de deux cytokines, BAFF et APRIL. Nos données montrent également que ce PS bactérien inhibe différentes réponses impliquant les cellules T (réponse humorale à un Ag thymo-dépendant, hypersensibilité retardée induite par un haptène fort). L’analyse phénotypique et fonctionnelle de cellules dendritiques exposées au PS3 nous conduit à proposer que le PS induit la différenciation des cellules dendritiques en cellules tolérogènes. L’ensemble de nos données suggèrent que l’état de compétence des APCs liée à leur fonction auxiliaire dans la réponse Ac aux Ag TI est équivalent à la fonction tolérogène, déjà documentée dans la littérature. Cette dualité des APCs induite par le PS (stimulatrices vis à vis de la réponse Ac, tolérogènes vis à vis des réponses cellulaires) pourrait jouer un rôle physiologique important au niveau de la muqueuse intestinale. / The humoral immune response against thymus-independent (TI) antigens (Ag) such as bacterial capsular polysaccharides (PS) does not require the help from T lymphocytes but needs a dialog between B cells and antigen presenting cells (APC). The particularity of TI Ag is their ability to generate an antibody response in vivo in the absence of exogenous danger signals. We have postulated that bacterial PS induce a competence status of the APC enabling them to act as auxiliary cells towards the B cells differentiation induced by TI Ag. In the present study, we have indentified the nature of the APC and explored the competence status induced by a capsular PS from S. pneumoniae (PS3). Our results show that both macrophages and dendritic cells (DC) can exert an auxiliary function towards the humoral response to TI Ag by secreting two major cytokines, BAFF and APRIL. We have also shown that bacterial PS suppress different responses involving T cells as humoral response to a thymus-dependent Ag and delayed hyper-sensitivity induced by a potent hapten. The phenotypical and functional analysis of DC exposed to PS3 led us to postulate that PS induces the differentiation of DC into tolerogenic cells. Altogether our findings suggest that the APC’s competence status enabling them to provide help to B cells against TI Ag is their tolerogenic function. This double function of the APC induced by PS (stimulatory towards antibody response and tolerogenic towards cellular responses) could be important in the intestinal mucosal sites.

Les lymphocytes B (LB) et les plasmocytes (PC) émergent comme des cellules importantes dans la surveillance immunitaire des tumeurs, même si leur rôle pro- ou anti-tumoral reste activement débattu. Nous avons émis l’hypothèse que cette dualité fonctionnelle de la réponse B pourrait être dictée par l'identité des sous-populations de LB infiltrant la tumeur et/ou par la nature des anticorps (Ac) qu’ils produisent. Dans ce contexte, nous avons montré que les tumeurs du sein et de l’ovaire sont souvent infiltrées par des LB mémoires et des PC exprimant/produisant principalement des IgG ou des IgA. Les IgA sont fortement enrichis dans les tumeurs mammaires in situ, plus précoces, et dans 15-20% des tumeurs invasives, suggérant un rôle différentiel des IgG et des IgA dans la progression tumorale. Les IgA, pouvant être monomériques ou dimériques dans les tumeurs, ciblent en général des antigènes (Ags) différents de ceux des IgG. Nous montrons de plus que les Ags ciblés par les IgA et les IgG sont souvent impliqués dans des fonctions de développement des tissus et d’interaction avec l’ADN, et sont parfois partagés entre patients et entre les types de tumeurs, suggérant leur importance dans la réponse anti-tumorale. En parallèle, grâce à l’étude des tumeurs de patientes souffrant d’un syndrome neurologique paranéoplasique, nous avons pu montrer que l’induction concomitante de PC à IgG et de LT CD8+ cytotoxiques dans la tumeur était liée à des amplifications et/ou des mutations dans les gènes des Ags tumoraux. Ces résultats mettent en évidence l’important des LB et des Ig dans la réponse anti-tumoral, et ouvre des pistes pour rechercher des cibles thérapeutiques en immunothérapie / B and plasma cells are rising as crucial cells in the immune surveillance of tumors, even though their pro- or anti-tumor role is still debated. We argue that this dual functionality of B cells could depend on the identity of tumor-infiltrating B cell subsets and/or by the nature of the antibodies they produce. With that knowledge, we showed that breast and ovarian tumors are usually infiltrated by memory B cells and plasma cells that express and/or produce mainly IgG or IgA. This last class of Ig in highly enriched in in situ carcinomas of the breast, corresponding to earlier tumors, and in 15-20% of invasive tumors, suggesting a differential role of IgG and IgA in tumor progression. IgA, that can be monomeric or dimeric in tumors, often target antigens that differ from those targeted by IgG. We also show that antigens targeted by IgA and IgG in the tumor are often involved in functions related to the development of tissues and DNA interactions, and can be share amongst patients and between breast and ovarian tumors, suggesting their importance in the anti-tumor immune response. In parallel, using tumors from patients suffering from a paraneoplastic neurological syndrome, we established that the concomitant induction of IgG PC and CD8+ cytotoxic T cells in the tumor is associated wth amplifications and/or mutations in the genes of tumor antigens. These results highlight the importance of B cells and Ig in the anti-tumor immune response and give leads to look for new targets in immunotherapy

En période néonatale, la muqueuse intestinale est immature et particulièrement perméable, notamment aux facteurs environnementaux comme les toxiques, les infections mais aussi les événements stressants. De la bonne maturation de la barrière intestinale va dépendre la mise en place de l'homéostasie intestinale et donc la tolérance vis-à-vis des antigènes luminaux. La survenu d’évènements stressants durant la petite enfance est associée au déclenchement et/ou l’entretien de pathologies gastro-intestinales fonctionnelles comme le Syndrome de l’Intestin Irritable (SII) mais aussi organiques comme les Maladies Inflammatoires Chroniques de l’Intestin (MICI). De plus, ces pathologies malgré leurs différences dans la sévérité et les signes cliniques, partagent un certain nombre de caractéristiques physiopathologiques communes, comme la rupture de l’intégrité de la barrière intestinale associée à une rupture de tolérance vis-à-vis des antigènes luminaux et plus particulièrement contre le microbiote intestinal. L’objectif de ce travail a été d’évaluer les effets d’un Stress de Séparation Maternelle (SSM) sur l’homéostasie intestinale et la réponse immunitaire vis-à-vis du microbiote commensal chez la souris jeune adulte. Nos résultats ont mis en évidence un dimorphisme sexuel dans ce modèle. Chez les souris mâles jeunes adultes, le SSM diminue les fonctions de la barrière intestinale associé à une altération de la réponse humorale et cellulaire au niveau systémique vis-à-vis du microbiote commensal, ainsi qu’à un défaut des cellules présentatrices d’antigènes, conduisant à une inflammation de bas grade malgré un profil proinflammatoire des lymphocytes T. Chez les souris femelles jeunes adultes, le SSM altère la fonctionnalité des cellules de Paneth associée à surpopulation bactérienne intestinale, responsable de la sensibilité viscérale en réponse à une distension colorectale et une réponse humorale systémique dirigée contre le microbiote commensal. Nous avons mis en évidence une empreinte du SSM chez le jeune adulte, capable d'induire des modifications profondes de l’homéostasie intestinale ainsi que de la réponse immunitaire systémique contre le microbiote intestinal. Le SSM altère l'homéostasie intestinale et reproduit des caractéristiques communes aux pathologies digestives à savoir une rupture de barrière associée à une réponse immunitaire contre le microbiote sans symptômes majeurs. Ce travail a permis d'identifier la survenue d'événements stressants pendant la petite enfance comme un facteur environnemental important capable d'altérer l'homéostasie intestinale chez des individus sains et qui pourrait contribuer au déclenchement de pathologies intestinales chez des individus génétiquement prédisposés. / Perinatal period is characterized by an immature intestinal barrier particularly permeable to luminal antigens and as such highly vulnerable to environmental factors like toxins, infections or stressful events. The appropriate maturation of intestinal barrier leads to intestinal homeostasis and tolerance toward luminal contents. Early life stressful events are associated with the development and/or maintenance of functional gastrointestinal disorders like Irritable Bowel Syndrome (IBS) or organic one like Inflammatory Bowel Diseases (IBD). These pathologies are highly different in term of etiology and clinical severity however they share common features like alteration in intestinal barrier associated with an abnormal immune response toward luminal contents especially commensal microbiota. Our aim was to evaluate the consequences of maternal separation (MS) on intestinal homeostasis, host-microbiota relationship and the humoral and cellular response at adulthood. Due to sexual dimorphism in this model, the results are presented separately for male and female. In young adult male mice, MS decreases intestinal barrier functions associated with an alteration of systemic humoral and cellular response toward commensal microbiota. Moreover, a defect of antigen presenting cells in spleen leads to systemic low grade inflammation despite a pro-inflammatory profile of T cell. In young adult female mice, MS alters the functionality of Paneth cells associated with an intestinal bacterial overgrowth, leading to visceral sensitivity and systemic humoral response toward commensal microbiota. We highlighted that MS has long lasting adverse effects on intestinal homeostasis and systemic immune response toward commensal microbiota in young adult. MS impairs intestinal homeostasis in healthy individuals and might contribute to trigger intestinal pathologies in susceptible persons.

Le streptocoque du groupe B (GBS) est un agent causant des septicémies et des méningites chez les nouveaux nés et chez les adultes. Une réaction sérologique dirigée contre la capsule polysaccharidique (CPS) permet de différencier les 10 sérotypes de GBS, dont le sérotype III qui est le plus fréquemment isolé en cas de méningite. Actuellement l’efficacité de l’unique traitement disponible, l’antibioprophylaxie intrapartum, est controversée. Dans l’optique d’élargir les options de prévention, cette étude vise à mieux comprendre les interactions entre GBS III et le développement de la réponse adaptative, sujet qui est peu documenté. Cette étude a évalué, par cytométrie en flux (FACS), les sous-populations des lymphocytes B (LB) spléniques impliquées suite à l’infection systémique de GBS III dans un modèle in vivo. De plus, la réponse humorale contre GBS III et contre la CPS III purifiée ainsi que la formation des centres germinatifs (GCs) spléniques dans un contexte de multiples infections par GBS ont été évalués. Les résultats suggèrent que la première infection stimule la production d’anticorps contre GBS III mais peu contre sa CPS. De plus, GBS III activerait la différenciation des LB et induirait la formation des GCs liée au déclenchement d’une réponse mémoire permettant un meilleur contrôle lors des infections subséquentes. Malgré sa faible immunogénicité, la CPS ne semblerait pas interférer avec le développement de l’immunité adaptative humorale contre la bactérie. La production d’anticorps contre GBS III qui implique la commutation de classe serait principalement produite contre des épitopes différents de ceux composant la CPS III. / Group B Streptococcus (GBS) is an agent of septicemia and meningitis in newborns but also in adults. A serological reaction directed against the polysaccharide capsule (CPS) allows to differentiate 10 GBS serotypes, including serotype III which is the most frequently isolated in cases of meningitis. Currently the effectiveness of the only available treatment, intrapartum antibiotic prophylaxis, is controversial. To improve prevention strategies, this study aims to better understand the interactions between GBS and the development of the adaptive response, a subject that is poorly documented. This study evaluated, by flow cytometry (FACS), the splenic subpopulations of B lymphocytes (LB) involved following systemic GBS infection in an in vivo model. This study also evaluated the serum anti-GBS antibody response and against its purified capsule as well as the formation of splenic germinal centers (GCs) in the context of multiple GBS infections. Results suggest that the first infection stimulates the production of antibodies against GBS III but little against its capsule. Furthermore, results suggest that GBS activates B cell differentiation by inducing the production of GCs, which are linked to triggering a memory response allowing better control in subsequent infections. Despite its low immunogenicity, the CPS does not appear to interfere with the development of adaptive humoral immunity against the bacteria. Therefore, the production of antibodies against GBS III, involving class switching, would recognize different epitopes from those found on its capsule.