Nitric oxide (NO) is expressed in inflammatory tissues. However, NO effects are controversial in inflammation; NO is described as acting in a dose dependent manner and possess both pro-inflammatory and anti-inflammatory properties. The present thesis explored the role of NO in relation to white blood cell (WBC) and protein system activation by foreign surfaces in simulated extracorporeal circulation (SECC) using human whole blood from volunteer donors. Three doses of NO, 40 ppm, 80 ppm and 500 ppm, were administered and an array of markers of WBC and protein activation were studied. Neutrophil degranulation was detected with myeloperoxidase (MPO), human neutrophil lipocalin (HNL) and lactoferrin (LF); eosinophil degranulation with eosinophil cationic protein (ECP) and eosinophil peroxidase (EPO); and basophil degranulation with histamine. Furthermore, whole blood and WBC capacity to produce reactive oxygen species (ROS) were studied and cytokine release was measured with IL-1 and IL-10. Complement activation was measured with C3a and C5b-9 complex and contact system activation with FXIIa-C1INH, FXIIa-AT, FXIa-C1INH and FXIa-AT. NO increased neutrophil degranulation at all dose levels and 80 ppm NO increased basophil degranulation; whereas, NO exerted no effect on eosinophil degranulation, WBC subset counts, cytokine release or capacity to produce ROS. In addition, while increasing both specific and azurophil degranulation with 40 ppm, 80 ppm and 500 ppm, NO reversed the classical degranulation hierarchy with 500 ppm and azurophil degranulation became predominant. Furthermore, NO effect was greater with 500 ppm than with 80 ppm, indicating a dose response effect. The lack of iNOS mRNA expression in WBC and lack of L-NAME effect on degranulation and nitrite/nitrate production, together with absent increase in nitrite/nitrate in controls, excluded autocrine or paracrine regulation of degranulation. FXIIa-AT and FXIa-AT complexes increased and became predominant during early recirculation, whereas FXIIa-C1INH and FXIa-C1INH complexes were predominant at baseline but remained unaltered, suggesting contact system inhibition predominantly via AT. C3a and C5b-C9 increased. NO had no effect on either contact or complement system activation; however, 500 ppm NO shortened active clotting time. In conclusion, the present data suggest that NO has a direct effect on neutrophil and basophil degranulation. Recognition of NO as an enhancer of degranulation may give access to new therapeutic tools for local and systemic inflammatory therapies; whereas, the identification of increased AT mediated inhibition of FXIIa and unchanged C1INH complexes presents new possibilities for therapeutic intervention in conditions such as hereditary angioedema and heart surgery.

Experimental models of a transfer of stem cells for therapeutic purposes Abstract Stem cell therapy currently represents a standard procedure of treating a wide variety of hereditary diseases and serious injuries. Development of the most suitable way of transfer of stem cells into the patient body remains very important question concerning this type of therapy. In our experiments we used nanofiber scaffolds for stem cell cultivation and their subsequent transfer. These nanofibers were prepared by the original needleless electrospun NanospiderTM technology. Allogeneic cornea or skin graft were transplanted from B6 mice to BALB/c mice. The grafts were covered by a nanofibrous scaffold with cultivated stem cells. Stem cells were stained by an imunofluorescent dye to enable us to monitore their migration from nanofibers into tissues and consequent distribution in the body and characterize changes of this distribution in the time. The methods of ELISA and PCR were used to confirm that mesenchymal stem cells support the production of antiinflammatory cytokines IL-4 and IL-10 and contribute to inhibition of production of proinflammatory cytokines IL-1, IFNγ and inducible nitric oxide synthase. We confirmed an important beneficial role of nanofiber scaffolds in transplantation of mesenchymal stem cells. Nanofiber...

A lesão tecidual é um dos efeitos locais descritos nos envenenamentos botrópicos. Toxinas isoladas, como: a jararagina (JAR) e bothropstoxina-I (BthTX-I), obtidas dos venenos de B. jararaca e B. jararacussu, respectivamente, induzem intensa resposta inflamatória e lesão tecidual, porém apresentam diferentes mecanismos de ação. Como descrito, a resolução da lesão tecidual envolve a interação entre mecanismos de reparo do tecido e o sistema imune. Neste contexto, a resposta inflamatória é iniciada por meio da detecção de sinais de dano tecidual agudo devido a distúrbios da homeostasia resultantes ou não de agentes microbianos (DAMPs) e/ou por reconhecimento de padrões moleculares associados a patógenos (PAMPs). Uma vez induzida, a resposta inflamatória está envolvida tanto no processo de lesão visando a eliminação do agente indutor, assim como no reparo tecidual. Diversos receptores estão envolvidos no reconhecimento de PAMPs e DAMPs como os transmembrânicos representados pelos do tipo Toll, e os citosólicos que compreendem complexos proteicos que formam os inflamassomas. Estes complexos multiproteicos citosólicos podem participar da indução da resposta imune inata por ativação de caspase-1 com consequente liberação de IL-1&#946, que pode resultar em morte celular. Considerando o exposto, o objetivo deste trabalho foi estudar a participação de inflamassoma na resposta inflamatória no tecido muscular de injeção das toxinas, a capacidade da BthTX-I e JAR de induzir a ativação de inflamassoma em macrófagos e os mecanismos moleculares envolvidos nesse processo. O estudo da migração de neutrófilos e macrófagos para o músculo gastrocnémio de animais C57BL/6 ou deficientes em caspase 1/11 (Caspase 1/11-/-) ou NLRP3 (NLRP3-/-) injetados com JAR e BthTX-I permitiu verificar que o inflamassoma NLRP3 participa da migração destas células inflamatórias para local de injeção das toxinas. A análise da produção de IL-1&#946 nas culturas de macrófagos peritoneais incubados com JAR e BthTX-I (6 e 24h) mostrou que somente a BthTX-I foi capaz de induzir a secreção desta citocina por um mecanismo dependente de caspase 1/11, ASC e NLRP3 e independente de IPAF. A incubação de macrófagos humanos com as toxinas permitiu verificar que ambas as toxinas induziram a secreção de IL-1&#946 dependente de caspase 1, porém esta produção foi significativamente maior em resposta à BthTX-I. Nos macrófagos peritoneais de camundongos observamos a relação entre a secreção de IL-1&#946 e morte celular em ensaio de incorporação do brometo de etídio nas culturas incubadas com BthTX-I por 24h e não com a JAR. Visto que ambas as toxinas injetadas via intramuscular induzem resposta inflamatória intensa, foi analisado o efeito delas sobre a viabilidade e secreção de IL-6 e MCP-1 em miotubos C2C12. Os resultados mostraram que somente a BthTX-I induz efeito miotóxico sobre esta linhagem celular. Além disso, pudemos verificar que BthTX-I induz altos níveis de IL-6 e MCP-1 quando comparados aos obtidos com a JAR. Visto que a BthTX-I induziu alta secreção de MCP-1 pelos miotubos C2C12, em experimento in vivo realizado em camundongos C57BL/6 ou deficientes em CCR2 (CCR2-/-) pode ser observada a dependência da interação entre MCP-1 e o CCR2 para a migração dos macrófagos em resposta a injeção de BthTX-I. Em culturas de miotubos incubados com as toxinas pôde ser observada alta liberação de ATP induzida pela BthTX-I in vitro. Em outros experimentos foi estudada a capacidade do sobrenadante de miotubos incubados com BthTX-I de induzir a secreção de IL-1&#946 pelos macrófagos in vitro. Os resultados mostraram a produção de IL-1&#946 nessas culturas de macrófagos, assim como a produção desta citocina em macrófagos incubados com BthTX-I juntamente com ATP. A hidrólise do ATP no sobrenadante da cultura de C2C12 estimulada com BthTX-I aboliu a secreção de IL-1 pelos macrófagos in vitro. Além disso, foi observada a inibição da produção de IL-1&#946 nas culturas de macrófagos primados com LPS e incubados com a BthTX-I em condições de altas concentrações de KCl sugerindo papel relevante do efluxo de K+ na produção de IL-1&#946 induzida pela BthTX-I. Em conjunto, os resultados acrescentam novas informações sobre o potencial inflamatório da JAR e BthTX-I, quanto à ação destas toxinas em macrófagos, ativação de inflamassoma e células musculares. / Tissue damage is one of the local effects described in bothropic envenomations. Isolated toxins, such as jararhagin (JAR) and bothropstoxin-I (BthTX-I), obtained from B. jararaca and B. jararacussu venoms, respectively, induce intense inflammatory response and tissue injury, however mediated by distinct mechanisms. As described, resolution of tissue injury involves the interaction between mechanisms of tissue repair and the immune system. In this context, the inflammatory response is initiated by detecting of signs of acute tissue damage due to disorders of homeostasis resulting from distinct agents (DAMPs) and / or recognition of pathogens associated molecular patterns (PAMPs). Once induced, the inflammatory response is involved both in the injury process for the elimination of the pathogenic agent, as well as in the tissue repair. Several receptors are involved in the recognition of PAMPs and DAMPs as the transmembrane receptors such as the Toll-like, and the cytosolic ones that comprise protein complexes - inflammasomes. These cytosolic multiprotein complexes may participate in the induction of the innate immune response by activation of caspase-1 with consequent release of IL-1&#946, which may result in cell death. Thus, we aimed to study the role of inflammasome on the inflammatory response in muscular tissue of JAR and BthTX-I injection, the ability of BthTX-I and JAR to induce the activation of inflammasome in macrophages and the molecular mechanisms involved in this process. The analyses of the neutrophils and macrophages migration in gastrocnemius muscle of C57BL/6 or Caspase 1/11 (Caspase 1/11-/-) or NLRP3 (NLRP3-/-) deficient mice injected with JAR e BthTX-I allow us to verify that NLRP3 inflammasome participates in these cells migration for the local of the toxins injection. The detection of IL-1&#946 on supernatants from macrophage cultures incubated with JAR or BthTX-I (6 e 24h) showed that only BthTX-I was able to induce this cytokine secretion by a mechanism dependent of caspase 1/11, ASC and NLRP3 and independent of IPAF. The incubation of human macrophages with the toxins demonstrated that both toxins induced IL-1&#946 secretion, however this production was significantly higher in response to BthTX-I. On murine macrophage cultures it was verified the correlation between the IL-1&#946 secretion and the cell death in the incorporation of ethidium bromide assay of cultures incubated with BthTX-I during 24h and not with JAR. Since that both toxins injected in the muscle induced intense inflammation, it was analyzed the effect of both toxins on the viability and the secretions of IL-6 and MCP-1 by C2C12 myotubes. The results showed that only BthTX-I induces a myotoxic effect on this cell line. Furthermore, it was verified that BthTX-I induces high secretion of IL-6 and MCP-1 when compared with those induced by JAR. Considering that BthTX-I induces high levels of MCP-1, in in vivo experiment using C57BL/6 and CCR2 deficient (CCR2-/-) mice it was observed that the interaction of MCP-1 and CCR2 is essential for the macrophage recruitment for the toxin injection. High release of ATP was detected in C2C12 myotube cultures incubated with BthTX-I but not with JAR. In another experiments it was studied the ability of the supernatants of C2C12 myotubes incubated with BthTX-I to induce the IL-1&#946 secretion by peritoneal macrophages in vitro. The results showed the IL-1&#946 secretion in the macrophage cultures as well as the cytokne secretion in macrophages incubated with BthTX-I and ATP independent of the priming with LPS. The hydrolysis of the ATP on the supernatants of C2C12 incubated with the BthTX-I abolished the IL-1&#946 production by macrophages in vitro. In addition, it was not observed IL-1&#946 production by macrophages primed with LPS and incubated with BthTX-I in the presence of high concentration of KCl suggesting a relevant role of K&#43 efflux for this cytokine secretion in response to BthTX-I. Taken together, the results show new findings about the inflammatory effect of JAR and BthTX-I, concerning about the action of these toxins on macrophages, inflammasome activation and muscle cell.

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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

De l'isolement des îlots pancréatiques à leur implantation, l'inflammation est omniprésente au cours de la transplantation d'îlots pancréatiques. Le maintien d'une inflammation contrôlée est essentiel pour préserver la survie et la fonctionnalité du greffon à court et long terme. L'objectif de ce travail de thèse est d'identifier précisément les mécanismes inflammatoires à l'origine de la perte précoce des îlots et de déterminer des cibles thérapeutiques pour limiter ces réactions inflammatoires.Nous avons ainsi démontré que les conditions de culture induisent des réactions à l'origine du développement d'un phénotype pro-inflammatoire et pro-oxydant propre à l'îlot. Cette induction se caractérise par une élévation de la sécrétion de cytokines, de chimiokines pro-inflammatoires, une activation des voies de l'inflammation Toll-like récepteurs (TLRs)-dépendantes et une génération d'espèces réactives de l'oxygène (ROS). Toutefois, ce processus peut être prévenu par l'activation de l'Hème oxygénase-1 (HO-1), une enzyme anti-oxydante et anti-inflammatoire.Par l'étude des réactions inflammatoires sur un modèle animal de transplantation mimant les conditions de transplantation humaine, nous avons démontré qu'un changement des médiateurs plasmatiques de l'inflammation et du protéome hépatique s'opère 12 heures après transplantation. De plus, ces résultats sont associés à une infiltration des îlots par les cellules immunitaires qui s'organise 12 heures après transplantation. Nous avons également établi le rôle anti-inflammatoire de la rapamycine (une drogue immunomodulatrice) sur les îlots et les macrophages in vitro. Nous avons ainsi démontré que l'usage de la rapamycine avec la mise en place d'un pré-traitement des îlots et du receveur avant la greffe serait envisageable. Ces travaux ont permis de caractériser les mécanismes inflammatoires mis en oeuvre immédiatement avant et après transplantation. Ainsi, ces données offrent de nouvelles pistes thérapeutiques susceptibles de prévenir et/ou limiter l'inflammation au cours de la transplantation d'îlots pancréatiques.