Os invertebrados impedem o estabelecimento de uma infecção através de uma resposta imune eficiente. Esta resposta envolve reações celulares e humorais. Existem poucos trabalhos sobre a imunidade das aranhas. O principal objetivo deste estudo foi verificar o papel dos hemócitos e dos peptídeos antimicrobianos na resposta imune da aranha Acanthoscurria gomesiana. Inicialmente, a localização relativa da gomesina e da acanthoscurrina foi determinada, mostrando que 58% dos hemócitos armazenam os dois peptídeos antimicrobianos. Além disso, foi verificado que a gomesina é direcionada aos grânulos dos hemócitos da forma de pró-peptídeo. Observou-se ainda, que após um desafio, os hemócitos migram para o sítio de infecção, onde deve secretar componentes da cascata de coagulação e peptídeos antimicrobianos. Além disso, os resultados mostraram que a fagocitose não é o principal mecanismo ativado após uma infecção. Assim sendo, as principais respostas imunes da aranha são através da coagulação e secreção dos peptídeos antimicrobianos. / Invertebrates avoid the infection establishment through an efficient immune response. This response consists in cellular and humoral reactions. Few data are available concerning the spider\'s immunity. The main aim of this study was to determine the role of hemocytes and antimicrobial peptides on the immunity of the spider Acanthoscurria gomesiana. Initially, the localization of gomesin and acanthoscurrin was determined, showing that 58% of hemocytes store both antimicrobial peptides. Moreover, our results show that gomesin is addressed to the hemocyte granules as a pro-peptide. We also demonstrate, by in vivo and in vitro experiments, that hemocytes migrate to the site of microbial infection. Once at the site of infection, hemocytes might secrete components of coagulation cascade and antimicrobial peptides. Besides, our results suggest that phagocytosis is not the major defense mechanism activated after microbial challenge. Therefore the main reactions involved in the spider defense might be through the coagulation and antimicrobial peptides secretion.

Encefalite auto-imune experimental (EAE) é o modelo animal da doença humana esclerose múltipla. Foi demonstrado que as estatinas podem ter efeitos benéficos na EAE. Diversos mecanismos de ação foram descritos para explicar esses efeitos, entre eles: estímulo a expressão de HO-1, inibição da expressão de Toll-like receptors (TLR) e inibição da produção de citocinas de padrão Th1. Estudamos o efeito de uma estatina, a sinvastatina, na evolução clínica da EAE e seus mecanismos de ação. Também avaliamos o papel do TLR4 na EAE. O tratamento com sinvastatina melhorou a evolução clínica da EAE nas doses de 1 e 5 mg/kg/dia. A análise do infiltrado celular no SNC mostrou mudança do padrão de diferenciação dos linfócitos com menor porcentagem de células produtoras de IL-17 nos grupos tratados em relação aos controles. Os animais TLR-4 -/- apresentaram melhor evolução da doença. Concluímos que o tratamento com sinvastatina melhora a evolução clínica da EAE através da inibição da produção de IL-17 e que animais TLR-4 -/- têm melhor desfecho clínico na EAE que os controles. / Experimental autoimmune encephalomyelitis (EAE) is considered the experimental model for the human multiple sclerosis disease. It has been demonstrated that statins, used as lipid-lowering agents, can have beneficial effects on EAE. Several actions have been described to explain these effects: enhancement of HO-1 expression, inhibition of Toll-like receptors expression and inhibition of Th1 cytokines. We have investigated the effect of a statin, simvastatin, on EAE clinical development and the mechanisms behind those effects. Simvastatin treatment ameliorated EAE clinical outcome at doses 1 and 5 mg/kg/day. SNC cellular infiltrates analysis showed altered pattern of differentiation with decreased percentage of IL-17-producing T lymphocytes in treated group comparing with controls. TLR4 -/- mice showed better clinical development. We concluded that simvastatin treatment ameliorates EAE clinical outcome through inhibition of IL-17 production. Mice TLR4 -/- have better EAE clinical outcome than WT controls.

Os invertebrados impedem o estabelecimento de uma infecção através de uma resposta imune eficiente. Esta resposta envolve reações celulares e humorais. Existem poucos trabalhos sobre a imunidade das aranhas. O principal objetivo deste estudo foi verificar o papel dos hemócitos e dos peptídeos antimicrobianos na resposta imune da aranha Acanthoscurria gomesiana. Inicialmente, a localização relativa da gomesina e da acanthoscurrina foi determinada, mostrando que 58% dos hemócitos armazenam os dois peptídeos antimicrobianos. Além disso, foi verificado que a gomesina é direcionada aos grânulos dos hemócitos da forma de pró-peptídeo. Observou-se ainda, que após um desafio, os hemócitos migram para o sítio de infecção, onde deve secretar componentes da cascata de coagulação e peptídeos antimicrobianos. Além disso, os resultados mostraram que a fagocitose não é o principal mecanismo ativado após uma infecção. Assim sendo, as principais respostas imunes da aranha são através da coagulação e secreção dos peptídeos antimicrobianos. / Invertebrates avoid the infection establishment through an efficient immune response. This response consists in cellular and humoral reactions. Few data are available concerning the spider\'s immunity. The main aim of this study was to determine the role of hemocytes and antimicrobial peptides on the immunity of the spider Acanthoscurria gomesiana. Initially, the localization of gomesin and acanthoscurrin was determined, showing that 58% of hemocytes store both antimicrobial peptides. Moreover, our results show that gomesin is addressed to the hemocyte granules as a pro-peptide. We also demonstrate, by in vivo and in vitro experiments, that hemocytes migrate to the site of microbial infection. Once at the site of infection, hemocytes might secrete components of coagulation cascade and antimicrobial peptides. Besides, our results suggest that phagocytosis is not the major defense mechanism activated after microbial challenge. Therefore the main reactions involved in the spider defense might be through the coagulation and antimicrobial peptides secretion.

Encefalite auto-imune experimental (EAE) é o modelo animal da doença humana esclerose múltipla. Foi demonstrado que as estatinas podem ter efeitos benéficos na EAE. Diversos mecanismos de ação foram descritos para explicar esses efeitos, entre eles: estímulo a expressão de HO-1, inibição da expressão de Toll-like receptors (TLR) e inibição da produção de citocinas de padrão Th1. Estudamos o efeito de uma estatina, a sinvastatina, na evolução clínica da EAE e seus mecanismos de ação. Também avaliamos o papel do TLR4 na EAE. O tratamento com sinvastatina melhorou a evolução clínica da EAE nas doses de 1 e 5 mg/kg/dia. A análise do infiltrado celular no SNC mostrou mudança do padrão de diferenciação dos linfócitos com menor porcentagem de células produtoras de IL-17 nos grupos tratados em relação aos controles. Os animais TLR-4 -/- apresentaram melhor evolução da doença. Concluímos que o tratamento com sinvastatina melhora a evolução clínica da EAE através da inibição da produção de IL-17 e que animais TLR-4 -/- têm melhor desfecho clínico na EAE que os controles. / Experimental autoimmune encephalomyelitis (EAE) is considered the experimental model for the human multiple sclerosis disease. It has been demonstrated that statins, used as lipid-lowering agents, can have beneficial effects on EAE. Several actions have been described to explain these effects: enhancement of HO-1 expression, inhibition of Toll-like receptors expression and inhibition of Th1 cytokines. We have investigated the effect of a statin, simvastatin, on EAE clinical development and the mechanisms behind those effects. Simvastatin treatment ameliorated EAE clinical outcome at doses 1 and 5 mg/kg/day. SNC cellular infiltrates analysis showed altered pattern of differentiation with decreased percentage of IL-17-producing T lymphocytes in treated group comparing with controls. TLR4 -/- mice showed better clinical development. We concluded that simvastatin treatment ameliorates EAE clinical outcome through inhibition of IL-17 production. Mice TLR4 -/- have better EAE clinical outcome than WT controls.

La leucémie lymphoblastique aiguë des cellules Pré-B (B-ALL) reste le type de cancer le plus souvent diagnostiqué chez les enfants. Des études ont montré que des déterminants génétiques jouent un rôle important dans la susceptibilité/résistance au développement de ce cancer. À cet égard, les gènes Killer-cell Immunoglobulin-like Receptor (KIR) sont d'une importance particulière. Ces gènes sont fortement polymorphiques et codent pour des récepteurs qui contrôlent l’activité fonctionnelle des cellules Natural Killer (NK). Notre hypothèse est que les gènes activateurs des KIR s’associent avec la résistance innée pour développer la B-ALL. Afin d'évaluer cette hypothèse, nous avons entrepris une étude de cas-contrôles chez des enfants canadiens-français dans laquelle nous avons utilisé l'ADN génomique de 100 patients atteints de B-ALL ainsi que l’ADN de 245 individus sains. La présence ou l'absence de chaque gène KIR a été détectée par PCR en utilisant des amorces de séquences spécifiques. Nous avons trouvé que la présence des gènes KIR activateurs est significativement diminuée chez les enfants leucémiques par rapport aux témoins. En outre, le nombre de ces gènes a aussi montré une association significative linéaire avec la résistance au développement d’une B-ALL. Cela suggère des effets additifs de ces gènes permettant de conférer une protection contre ce cancer. Ces résultats pourraient être utiles afin de déceler de façon précoce les enfants ayant un risque de développer cette leucémie. Enfin, des stratégies thérapeutiques basées sur les récepteurs KIR pourraient être envisagées et s'avérer utiles concernant le traitement de ce cancer chez les enfants. / Investigating genetic determinants that play a role in conferring susceptibility/resistance to the development of acute B cell leukemia (B-ALL) in children is highly desirable. We hypothesized that activating Killer-cell Immunoglobulin-like Receptor (KIR) genes, which are implicated in NK cell activation, may represent one of these determinants. To test this hypothesis, we conducted a case-control study in French-Canadian children in which we used genomic DNA from 100 B-ALL patients and 245 healthy controls. The presence or absence of each KIR gene was detected by PCR using sequence-specific primers. We found that the frequencies of these genes are significantly reduced in B-ALL cases when compared with their healthy counterparts. Furthermore, we found that these genes had an additive effect in reducing risk for developing the cancer. The results may be useful in early identification of children at risk for developing this cancer. Moreover, KIR-based therapies may prove to be useful in treating this cancer.

La leucémie lymphoblastique aiguë des cellules Pré-B (B-ALL) reste le type de cancer le plus souvent diagnostiqué chez les enfants. Des études ont montré que des déterminants génétiques jouent un rôle important dans la susceptibilité/résistance au développement de ce cancer. À cet égard, les gènes Killer-cell Immunoglobulin-like Receptor (KIR) sont d'une importance particulière. Ces gènes sont fortement polymorphiques et codent pour des récepteurs qui contrôlent l’activité fonctionnelle des cellules Natural Killer (NK). Notre hypothèse est que les gènes activateurs des KIR s’associent avec la résistance innée pour développer la B-ALL. Afin d'évaluer cette hypothèse, nous avons entrepris une étude de cas-contrôles chez des enfants canadiens-français dans laquelle nous avons utilisé l'ADN génomique de 100 patients atteints de B-ALL ainsi que l’ADN de 245 individus sains. La présence ou l'absence de chaque gène KIR a été détectée par PCR en utilisant des amorces de séquences spécifiques. Nous avons trouvé que la présence des gènes KIR activateurs est significativement diminuée chez les enfants leucémiques par rapport aux témoins. En outre, le nombre de ces gènes a aussi montré une association significative linéaire avec la résistance au développement d’une B-ALL. Cela suggère des effets additifs de ces gènes permettant de conférer une protection contre ce cancer. Ces résultats pourraient être utiles afin de déceler de façon précoce les enfants ayant un risque de développer cette leucémie. Enfin, des stratégies thérapeutiques basées sur les récepteurs KIR pourraient être envisagées et s'avérer utiles concernant le traitement de ce cancer chez les enfants. / Investigating genetic determinants that play a role in conferring susceptibility/resistance to the development of acute B cell leukemia (B-ALL) in children is highly desirable. We hypothesized that activating Killer-cell Immunoglobulin-like Receptor (KIR) genes, which are implicated in NK cell activation, may represent one of these determinants. To test this hypothesis, we conducted a case-control study in French-Canadian children in which we used genomic DNA from 100 B-ALL patients and 245 healthy controls. The presence or absence of each KIR gene was detected by PCR using sequence-specific primers. We found that the frequencies of these genes are significantly reduced in B-ALL cases when compared with their healthy counterparts. Furthermore, we found that these genes had an additive effect in reducing risk for developing the cancer. The results may be useful in early identification of children at risk for developing this cancer. Moreover, KIR-based therapies may prove to be useful in treating this cancer.