INTRODUÇÃO: A paracoccidioidomicose (PCM) induz uma resposta imune tipo Th1 relacionada à proteção, com imunodepressão antígeno-específica transitória. As células dendríticas (DCs) são as mais potentes apresentadoras de antígeno, porém, pouco se sabe sobre seu papel na PCM humana e sobre os efeitos do fungo em suas funções. OBJETIVO: Investigar os efeitos in vitro de antígenos de Paracoccidioides brasiliensis (P. brasiliensis) sobre as DCs derivadas de monócitos de pacientes com PCM. MÉTODOS: Foram incluídos 27 pacientes com PCM ativa (PA; com diagnóstico micológico, histopatológico ou títulos de anticorpos anti-P. brasiliensis >= 32) e 31 pacientes com PCM tratada (PT; anticorpos anti-P. brasiliensis com títulos <= 4, em duas coletas num período de 6 meses, e doença comprovada no passado pelos mesmos critérios de pacientes com PCM ativa), e de 39 indivíduos sadios (CO; não sensibilizados a antígenos de P. brasiliensis e sem anticorpos a tais antígenos fúngicos) foram geradas a partir de monócitos do sangue periférico, tratados com IL-4 e GM-CSF. As DC diferenciadas não-tratadas (nDC) ou tratadas com TNF-alfa (DC+TNF) foram estimuladas com os antígenos de P. brasiliensis: glicoproteína de 43 kDa (gp43) a 2 e 5 ug/mL (Gp2 e Gp5), e antígeno solúvel a 15 ug/mL (CFA). As moléculas de superfície CD11c, CD1a, HLA-DR, CD86, CD80 e DC-SIGN das DCs foram analisadas por citometria de fluxo e as citocinas IL-10, IL-12p40, IL-1beta e CCL18 foram dosadas nos sobrenadantes das culturas por ELISA. As DCs foram então co-cultivadas com linfócitos autólogos, medindo-se a linfoproliferação por incorporação de timidina triciada e dosando-se por ELISA os níveis de citocinas IL-10, IL-4, IFN-y e TNF-alfa foram dosadas nos sobrenadantes dessas culturas. RESULTADOS: As DCs de PA e PT apresentaram expressão de CD11c e CD1a similar à observada nas DCs de CO. No grupo PT, Gp5 induziu maior expressão de HLA-DR em comparação ao grupo PA, e o CFA aumentou o percentual de DCs CD86+. As DCs de PT, na presença de TNF-alfa, secretaram grandes quantidades de IL-12p40, especialmente frente ao CFA. Este antígeno induziu forte proliferação de linfócitos autólogos tanto de pacientes do grupo PA quanto do grupo PT, em relação ao grupo CO e às células sem CFA. Os níveis de IL-10 foram maiores no grupo PA, enquanto que os de IL-4 foram maiores no grupo PT, tanto nos co-cultivos com DCs e Gp quanto com DCs e CFA. Por outro lado, apenas o estímulo de DCs com CFA, e não com gp43, induziu altos níveis de IFN-y e TNF-alfa. CONCLUSÕES: DCs de PT tem alta expressão de HLA-DR, CD86 e DC-SIGN, altos níveis de IL-12p40 e baixos de IL-10, induzidos por CFA. DCs de PA apresentam expressão de moléculas similar às de DCs de indivíduos sadios, e baixos níveis de IL-12-p40 e IL-10. A gp43 induziu pouca linfoproliferação e baixos níveis de IFN-y e TNF-alfa nos co-cultivos de linfócitos autólogos e DCs de PT e PA. O CFA foi mais eficiente que a gp43 no estímulo de DCs PT e PA mas não de CO, ao induzir proliferação de linfócitos autólogos com aumento da secreção de IFN-y e TNF-alfa. Esses resultados, combinados aos níveis constantes de IL-10 e altas concentrações de IL-12p40, sugerem que o CFA seja melhor indutor de resposta Th1, podendo servir como alvo para pesquisas de epítopos candidatos à vacina de células dendríticas anti-P. brasiliensis. / INTRODUCTION: Paracoccidioidomycosis (PCM) induces a Th1 immune response associated with protection, with a transitory antigen-specific immunodepression. Dendritic cells (DCs) are the most potent antigen presenting cells, but little is known about their role on human PCM and the effects of fungal antigens on their functions. OBJECTIVE: To investigate the in vitro effects of Paracoccidioides brasiliensis (P. brasiliensis) antigens on monocyte-derived DCs from patients with PCM. METHODS: Twenty-seven patients with active PCM (PA; with mycological or histopathological diagnosis or antibody titles anti-P. brasiliensis >= 32) and 31 treated PCM (PT; antibody titles <= 4 on two samples within six months, and proved disease in the past by the same criteria of active PCM) and from 39 non-PCM subjects (CO; non-sensitized to P. brasiliensis antigens and without anti-fungal antigens antibodies) were included in this study and DCs were generated from peripheral blood monocytes with IL-4 and GM-CSF. Differentiated DCs were treated with TNF-alfa (DC+TNF) or left untreated (nDC) and then stimulated with P. brasiliensis antigens: 43 kDa glycoprotein (gp43) at 2 and 5 ug/mL (Gp2 and Gp5), and the cell-free antigen at 15 ug/mL (CFA). Surface molecules CD11c, CD1a, HLA-DR, CD85, CD80 and DC-SIGN were analyzed by flow cytometry and the cytokines IL-10, IL-12p40, IL-1beta and CCL18 were assayed by ELISA. DCs were cocultured with autologous lymphocytes: lymphoproliferation was measured by the incorporation of tritiated thymidine and the cytokines IL-10, IL-4, IFN-y and TNF-alfa were also assayed by ELISA. RESULTS: DCs from PA and PT groups showed similar expression of CD11c and CD1a to those of CO group. On the PT group, Gp5 induced higher expression of HLA-DR when compared to PA and CFA increased the percentage of CD86+ DCs. When stimulated with CFA, TNF-alfa -treated DCs from the PT group secreted large amounts of IL-12p40. This antigen also induced strong proliferation of autologous lymphocytes on both PA and PT groups in comparison to CO group and to unstimulated cells. Both DCs with CFA and DCs with gp43 induced high levels of IL-10 and IL-4 on the PA and PT groups, respectively. On the other hand, only DCs with CFA and not those with gp43 were able to induce high levels of IFN-y and TNF-alfa. CONCLUSIONS: CFA-stimulated DCs from treated PCM showed high expression of HLA-DR, CD86 and DC-SIGN, increased levels of IL-12p40 and low levels of IL-10. DCs from patients with active disease have expression of surface molecules similar to those of non-PCM subjects, with low levels of IL-12p40 and IL-10. Gp43 induced low lymphoproliferation and decreased levels of IFN-y and TNF-alfa in the cocultures of DC and autologous lymphocytes from PT and PA groups. CFA was more efficient than gp43 on stimulating DCs to induce proliferation of autologous lymphocytes with increased secretion of IFN-y and TNF-alfa on both PT and PA cells but not on CO. These results combined with constant levels of IL-10 and high amounts of IL-12p40 suggest that CFA may be a better inducer of Th1 immune response and a suitable target for future researches on epitopes candidates for anti-P. brasiliensis dendritic cell-based vaccines

Neste trabalho nós mostramos que células dendríticas (DCs) de camundongos BALB/c expressam receptor para o PAF (Fator ativador de Plaquetas) e que sua ativação promove um fenótipo tolerogênico, associado à produção de IL10 e PGE2. O bloqueio do PAF-receptor por antagonistas aumentou a capacidade das DCs induzirem proliferação de linfócitos T. O antagonista WEB2170 potencializou a resposta imune in vivo a concentração de anticorpo IgG2a OVA-específico aumentou 30 vezes no grupo tratado; a concentração de IgG1 foi semelhante nos dois grupos. O bloqueio do PAFR em camundongos imunizados com OVA em adjuvante completo de Freund, aumentou a produção de IgG1 e IgG2a OVA-específicos. Em camundongos imunizados com OVA/alum o antagonista não alterou a produção de IgG1. Estes resultados indicam que a ativação do PAFR em DCs modula a sua função apresentadora de antígenos pela produção de IL10 e PGE2. O bloqueio do PAFR pode ser útil na ativação das DCs em protocolos de vacinação com DCs e/ou como co-adjuvante em protocolos de imunização. / In the present work we show that BALB/c mice dendritic cells (DCs) express the PAF (platelet-activating factor) receptor and that its activation promotes a tolerogenic phenotype via IL10 and PGE2 production. Blocking PAFR by selective antagonists markedly enhanced DCs ability to induce T cell proliferation. The antagonist WEB2170 potentiated the in vivo immune response the IgG2a OVA-specific levels were 30 fold increased in the treated group; IgG1 concentration was similar for both groups. The PAFR blockade in mice immunized with OVA in complete Freunds adjuvant enhanced both IgG1 and IgG2a OVA-specific antibody production. In OVA/alum immunized mice, the antagonist did not change IgG1 production. These results suggest that PAFR activation in DCs modulates their antigen-presenting function through IL10 and PGE2 production. Blocking PAFR may be useful to induce DCs activation in DCs-based vaccination protocols and/or as a co-adjuvant in immunization protocols.

Considerando que processos cruciais de diferenciação e maturação das células dendríticas (DCs) são regulados pelo fator de transcrição nuclear kappa B (NF-&#954;B), nos propusemos a estudar esta via em DCs derivadas de monócitos de pacientes com câncer de mama, partindo da hipótese de que alterações desta via contribuam, nesses indivíduos, para a geração de DCs com fenótipo e função alterados, levando ao escape tumoral. A análise da presença de NF-&#954;B no núcleo de monócitos, DCs imaturas (iDCs) e maduras indicou que as pacientes falham em modular tal fator de transcrição, de modo que a quantidade de NF-&#954;B no núcleo de iDCs de pacientes supera os níveis encontrados em controles, fenômeno possivelmente decorrente de alterações nas proteínas inibidoras do NF-&#954;B em pacientes. Observou-se menor frequência de células CD86+, CD83+ e HLA-DR+ (p < 0,05) ao final das culturas das pacientes, e aumento na concentração de IL-8 no sobrenadante das culturas. Coletivamente, estes dados corroboram a hipótese formulada. / Considering that crucial processes of differentiation and maturation of dendritic cells (DCs) are regulated by nuclear factor kappa B (NF-&#954;B), we proposed to study this pathway in monocyte-derived DCs from breast cancer patients, based on the hypothesis that alterations in such pathway may contribute in these individuals to the generation of DCs having phenotypic and functional changes, leading to tumor escape. The analysis of the presence of NF-&#954;B in the nucleus of monocytes, immature and mature DCs indicated that patients fail to modulate this transcription factor, so that the amount of NF-&#954;B in the nucleus of iDCs from patients exceeds levels found in controls, a phenomenon possibly due to alterations in inhibitory proteins of NF-&#954;B in patients. It was also observed diminished frequency of CD86+, CD83+ and HLA-DR+ cells (p <0.05) at the end of the patients cultures, as well as increased IL-8 concentration in the culture supernatants. Collectively, these data support the hypothesis previously formulated.

Células dendríticas (DCs) participam tanto da geração da resposta imune adaptativa como na manutenção da tolerância. O veneno da cascavel Crotalus durissus terrificus, sua principal toxina, crotoxina (CTX) e sua subunidade CB (fosfolipase A2), apresentam efeito supressor sobre o sistema imunológico. Neste trabalho foi avaliado o efeito da CTX e CB sobre a ativação/função das DCs e consequente indução de resposta adaptativa específica anti-Ovalbumina (OVA). Primeiramente, foi verificada a eficiência do processo de maturação das DCs incubadas com OVA associada ao LPS. Os resultados obtidos nesse modelo in vitro mostraram que a CTX e CB inibiram a maturação das DCs estimuladas com OVA &#43; LPS, caracterizada por menor expressão de moléculas coestimuladoras, MHC-II e secreção de citocinas pró-inflamatórias. Em contraste, a CTX e CB induziram maior expressão de ICOS-L, PDL1/2 nas DCs incubadas com OVA &#43; LPS assim como a expressão de RNAm para IL-10 e TGF-&beta;. Além disso, ambas as toxinas foram capazes de aumentar a expressão de PDL1, mas não de ICOS-L ou PDL-2 em DCs. Com relação ao mecanismo envolvido no efeito da CTX e CB sobre as DCs, os resultados mostraram o envolvimento dos receptores peptídeo-formil (FPRs) e a via da 5-Lipoxigenase nesse processo. Sobre a imunidade adaptativa, os resultados mostraram menor proliferação de células TCD3&#43; ou TCD4&#43; obtidas de animais imunizados com OVA quando co-cultivadas com DCs incubadas com ConA ou OVA &#43; LPS na presença de CTX ou CB. A diferenciação de células Th1 e Th2 foi inibida pela adição de CTX ou CB nas co-culturas com DCs estimuladas com LPS. No entanto, verificou-se aumento da população Treg nas co-culturas de células CD4&#43; e DCs incubadas com LPS &#43; CTX ou CB em comparação com DCs estimuladas somente com LPS. A CTX e CB inibiram a diferenciação de células CD4&#43; Tbet&#43; e CD4&#43;Gata3&#43; nas co-culturas de TCD4&#43; purificados de animais DO 11.10 com DCs estimuladas com OVA &#43; LPS. No entanto, apenas a CTX foi capaz de induzir aumento da porcentagem de células CD4&#43;CD25&#43;FoxP3&#43;. Em experimentos in vivo, foi observada menor proliferação e secreção de IL-2 e IFN nas culturas de células de camundongos imunizados com OVA que receberam CTX ou CB quando estimuladas com OVA em comparação com o observado nas culturas de células de camundongos imunizados com OVA. CTX e CB administradas in vivo em camundongos imunizados com OVA também inibiram a porcentagem de células CD4&#43;IFN&#43;, CD4&#43;IL-4&#43; e promoveram aumento da população CD4&#43;IL-10&#43; em comparação com o obtido em camundongos imunizados somente com a OVA. Em relação à imunidade humoral, a produção de anticorpos IgG1 e IgG2a anti-OVA também foi inibida em camundongos imunizados com OVA que receberam a CTX ou CB. Além disso, a reação de hipersensibilidade do tipo tardio foi suprimida somente em camundongos imunizados com OVA e que receberam a CTX. Estes dados demonstram que a CTX e CB exercem efeito regulador sobre o sistema imune inato e adaptativo e os FPRs bem como a via da 5-lipoxigenase estão envolvidos nessa ação imunomoduladora. / Dendritic cells (DCs) are involved in both the generation of the adaptive immune response and maintenance of the tolerance. The Crotalus durissus terrificus rattlesnake venom, its main toxin, crotoxin (CTX) and CB (phospholipase A2) subunit have suppressive effect on the immune system. In this work it was analyzed the effect of CTX and its CB subunit on the activation/function of DCs and consequent induction of anti-ovalbumin immune response. Firstly, the efficiency of the DCs maturation incubated with OVA associated with LPS was verified. Following, the results obtained in this in vitro model showed that CTX and CB inhibited the maturation of DCs stimulated with OVA + LPS, characterized by lower expression of costimulatory, MHC-II molecules on DCs as well as secretion of proinflammatory cytokines. In contrast, CTX and CB induced an enhancement of ICOS-L, PDL1/2 expression on DCs incubated with OVA, &#43;LPS as well as the expression of IL-10 and TGF-&#223; RNAm. In addition, both toxins were able to increase the expression of PDL1, but not ICOS-L or PDL-2, on DCs. Regarding the mechanism involved in the effect of CTX and CB on DCs, the results showed the involvement of the formyl-peptide receptors (FPRs) and the 5-Lipoxygenase pathway in this process. On adaptive immunity, the results showed lower proliferation of TCD3&#43; or TCD4&#43; cells obtained from mice immunized with OVA when co-cultured with DCs incubated with ConA or OVA &#43; LPS in the presence of CTX or CB. The differentiation of Th1 and Th2 cells were inhibited by the addition of CTX or CB in co-cultures with DCs stimulated with LPS. However, it was verified increased Treg population in co-culture of CD4&#43;cells and DCs incubated with LPS plus CTX or CB compared with DCs LPS-stimulated. CTX and CB inhibited the differentiation of of CD4&#43;Tbet&#43; and CD4&#43;Gata 3&#43; cells in co-cultures of TCD4&#43; purified from DO11.10 mice with DCs stimulated with OVA &#43; LPS. However, only CTX was able to increase the percentage of CD4&#43;CD25&#43;FoxP3&#43; cells. In in vivo experiments, it was observed lower proliferation and IL-2 and IFN secretions in cell cultures of mice immunized with OVA that received CTX or CB incubated with OVA compared with those observed in cell culture of OVA-immunized mice. The administration of CTX and CB in vivo in mice immunized with OVA also inhibited the percentage of CD4&#43;IFN&#43;, CD4&#43;IL-4&#43; cells and increased the CD4&#43;IL-10&#43; population compared with those observed in mice immunized with OVA. In relation to the humoral immunity, the production of anti-OVA IgG1 and IgG2a antibodies was also inhibited in mice immunized with OVA that received CTX or CB. In addition, the delayed hypersensitivity reaction (DTH) was also diminished in mice immunized with OVA that received the CTX. These data demonstrate that CTX and CB exert regulatory effect on innate and adaptive immune system and that FPRs as well as the 5-lipoxygenase pathway are involved in this immunomodulatory activity.

Initialement développés pour leur action inhibitrice sur les lymphocytes T, les immunosuppresseurs affectent aussi les cellules dendritiques (CD). Nous avons précédemment montré que l’acide mycophénolique (MPA) induisait une résistance des CD humaines à la maturation, néanmoins son mécanisme d’action sur les CD reste méconnu. Ce travail de thèse montre que le MPA inhibe l’activation de p38MAPK et que cette propriété entraîne l’inhibition de la maturation phénotypique induite par le facteur nécrotique tumoral a (TNFa), la diminution de la sécrétion de cytokines pro-inflammatoires et de la capacité allostimulatrice induite par le TNFa ou le lipopolysaccharide suggérant que l’inhibition de la synthèse de cytokines inflammatoires serait déterminante pour inhiber la capacité allostimulatrice. Nous rapportons également que le MPA inhibe la phosphorylation de ERK induite par le TNFa. Ainsi, l’action du MPA sur les CD s’exerce différemment selon l’environnement dans lequel se trouvent les CD. / Immunosuppressive drugs, initially developed to inhibit T cell activation, are also known now to affect dendritic cell (DC) functions. Previous works from our laboratory showed that mycophenolic acid (MPA) induced a resistance to maturation in human DC, however its mechanism of action in DC, remains elusive. In this study, we found that MPA inhibited p38MAPK phosphorylation independently. This p38MAPK inhibition resulted in a decrease phenotypic maturation upon tumor necrosis factor-a (TNF-a) stimulation and in a decrease in the pro-inflammatory cytokine secretion upon either lipopolysaccharide or TNF-a activation. MPA also decreased allostimulatory ability after both stimuli suggesting that inflammatory cytokine inhibition was predominant over co-stimulation marker reduction to inhibit the DC allostimulatory ability. We also showed that MPA only inhibited the TNFa-induced ERK phosphorylation. Thus, the microenvironnement of the DC might influence its ability to response to MPA.

En transplantation d’organes, la réponse immunitaire de l’hôte contre son donneur reste une cause très importante de perte de greffons. Ainsi, un meilleur contrôle de la réponse par induction d’une tolérance spécifique reste une priorité en transplantation humaine. Dans ce travail, nous avons exploré les effets de l’acide mycophénolique (MPA, immunosuppresseur couramment utilisé en transplantation) sur les cellules dendritiques (DC) humaines. Nous avons mis en évidence que le MPA diminue la capacité des DC à activer des lymphocytes T CD8+ cytotoxiques allogéniques en diminuant la synthèse d’interféron gamma dans les DC. Par ailleurs, les DC traitées par MPA sont capables d’induire des lymphocytes T CD4+ régulateurs antigène-spécifiques (iTreg) qui peuvent reprogrammer des DC matures en DC aux propriétés tolérogènes. Enfin, ces iTreg entraînent une réduction de la sécrétion d’IFN-γ par les cellules T CD8+ et une inhibition de leur fonction cytotoxique en réponse à une stimulation allogénique. L’ensemble de ces résultats obtenus in vitro suggèrent que les DC-MPA humaines pourraient être potentiellement utilisés en thérapie cellulaire afin de promouvoir une tolérance d’allogreffe. / In organ transplantation, host immune response against donor still remains a major cause of graft loss. A better control of allogeneic response through the induction of specific tolerance is a major goal in human transplantation. In this work, we explored the effects of mycophenolic acid (MPA, an immunosuppressive drug currently used in transplantation) on dendritic cell (DC) functions. We demonstrated that MPA inhibits DC ability to induce allogeneic cytotoxic CD8+ T cells through inhibition of interferon gamma synthesis in DC. Moreover, mycophenolic acid-treated dendritic cells (MPA-DC) are able to induce antigen-specific regulatory CD4+ T lymphocytes (iTreg) which can convert fully mature DC into tolerogenic DC. These iTreg decrease the expression of proteins associated with cytotoxic function (perforin and granzymes A and B), reduce IFN-γ production by CD8+ T cells and inhibit their cytotoxic function in response to allogeneic stimulation. These results taken together suggest that human MPA-DC could be use in cellular therapy in order to promote allograft tolerance.

Les pDC représentent la première ligne de défense de l’organisme contre les pathogènes et établissent le lien essentiel entre l’immunité innée et adaptative. Les pDC endocytent et détruisent les particules virales et ainsi détectent leur matériel génétique grâce à des senseurs antiviraux de la famille des Toll-Like Receptors (TLR). L’activation des TLR7/9 induit la production massive d’interféron de type I (IFN-I), un antiviral puissant indispensable au contrôle de la propagation virale lors des phases aigues de l’infection. Cependant, l’IFN-I peut s’avérer avoir des effets délétères dans un grand nombre d’infections chroniques et de maladies auto-immunes. Ainsi, il semble indispensable de découvrir les mécanismes régulateurs des pDC ainsi que des modulateurs de l’activation des pDC. Nous avons ainsi montré que les monoamines (histamine, dopamine, sérotonine) et les polyamines (spermine et spermidine) inhibent l’activation complète des pDC stimulées par divers virus. Par la suite, nous avons identifié CXCR4 comme étant le récepteur des amines sur les pDC. Ainsi nous avons pu montrer que les amines pouvaient réguler les pDC en passant par CXCR4 et que ce récepteur était un interrupteur d’activation potentiel des pDC lors des infections virales. Afin de comprendre le mécanisme des amines, nous avons développé une nouvelle technologie : la transfection de siRNA dans les pDC primaires humaines. D’autre part, nous avons détecté des cellules géantes multinucléées en forme de roue de bicyclette lorsque les pDC sont cultivées in vitro avec de grandes quantités de virus VIH. Ainsi, comme les monocytes et les macrophages, les pDC peuvent former in vitro des cellules géantes multinucléées exprimant de hauts niveaux de protéines virales p24 de VIH-1. Cependant, les pDC ne sont que très peu infectées (moins de 5%). Nous nous sommes alors demandé si le corécepteur CXCR4 du virus VIH était aussi important que le récepteur CD4 pour la reconnaissance de ce dernier lors de l’activation des pDC. / PDC are the first line of defense of our organism against pathogens and establish the essential link between the innate and adaptive immunity. pDC endocyte and destroy the viral particles and thus, detect the genetic material with their antiviral sensors from the Toll-Like Family (TLR). The activation of TLR7/9 induces massive production of type I interferon (IFN-I), a powerful antiviral molecule, essential to control viral propagation during the acute phases of the infection. However, type I IFN can have deleterious effects in a large number of chronic infections and autoimmune diseases. Thus, it seems essential to discover the regulatory mechanism of pDC as well as pDC activation modulators. We showed that monoamines (histamine, dopamine and serotonin) and polyamines (spermine and spermidine) inhibit completely the activation of virus-stimulated pDC. Thus, we showed that amines regulated pDC activation through CXCR4 engagement and that this receptor was a potential switch "on-off" for pDC during viral infections. To better understand the mechanism of action by which amines inhibit pDC activation, we developed a new technology: siRNA transfection in human primary pDC. Furthermore, we detected multinuclear giant cells bearing the shape of a bicycle wheel when pDC are cultured in vitro with high quantities of HIV virus. Thus, on top of monocytes and macrophages, pDC can form in vitro multinuclear giant cells with high levels of p24 viral protein of HIV-1. However, pDC barely get infected (less than 5%). We then wondered if the receptors and co-receptors of the virus were important for the viral recognition during HIV-activation of pDC.

A transmissão vertical do HIV-1 da mãe para criança foi significativamente reduzida com o uso de terapias antirretrovirais, resultando um aumento do número de crianças que foram expostas ao vírus. Estudos evidenciam a expressão de receptores Toll-like (TLR) em células trofoblásticas que pode ser uma ferramenta importante para regular a diferenciação e ativação de células do sistema imunológico, orquestrando um ambiente imunorregulador, contribuindo para o sucesso gravidez e proteção do feto. Considerando que as consequências da infecção por HIV-1 no microambiente placentário, na mãe e no recém-nascido (RN) não são bem entendidos, salienta-se a necessidade de investigar estratégias que possam potencializar a resposta imune inata, neste contexto. Com isso, no presente trabalho, foram avaliados as células mononucleares (CMN) do sangue periférico e cordão umbilical (RN) de parturientes infectadas por HIV-1 e parturientes-RN não infectados, a secreção de TNF-a, IL-10 e IFN-a induzida por agonistas de TLRs extracelular (TLR2, TLR4 e TLR5) e agonistas de TLRs intracelulares (TLR3, TLR7, TLR7/8, TLR9). Além disso, como sensor da resposta imune inata foi avaliado o perfil de resposta de células dendríticas mielóides (mDC) e plasmocitóides (pDC), após ativação com ligantes relacionados com resposta antiviral (TLR7, TLR7/8 e TLR9). No microambiente placentário foi verificada a expressão de CD123, TLR8, CD14/CD16 e HLA-G de amostras da decídua e vilo de mães infectadas por HIV-1 e grupo controle. Os resultados mostraram que as CMNs de mães infetadas por HIV-1 e de seus RNs têm um déficit na secreção TNF-a após ativação pelas vias de TLR2, TLR5, TLR3, TLR7, contudo, preservada para estimulação TLR7/TLR8 (composto CL097), principalmente pelas células de recém-nascidos. Além disso, apenas a ativação com CL097 foi eficaz para induzir a secreção IL-10 e IFN-a pelo grupo infectado, tanto na mãe quanto no RN. O CL097 também foi capaz de induzir a expressão de RNAm para o fator regulador de interferon-7 (IRF-7), IFN-a e TNF-a em níveis similares entre os grupos, confirmando o potencial de ativação TLR7/8. A ativação via TLR7/TLR8 foi capaz de controlar o déficit na da produção de TNF-a pelas mDC, mas não reverteu a resposta funcional de IFN-a por pDCs nas mães e RN infectados por HIV-1. No tecido placentário infectado por HIV-1, houve aumento da expressão de TLR8, CD123, e HLA-G. Os achados mostraram a importância da via TLR8 tanto na resposta sistêmica como no microambiente placentário, ressaltando a importância dos ligantes naturais e/ou sintético no papel adjuvante para melhorar a resposta antiviral na interação materno-fetal. / Mother-to-child transmission of HIV-1 has been significantly reduced with the use of antiretroviral therapies, resulting an increased number of HIV1-exposed uninfected infants. Studies have been evidenced that expression of Toll-like receptors (TLR) in trophoblast cells may be a relevant tool to regulate the differentiation and activation of immune cells, orchestrating an immunoregulatory environment, contributing to successful pregnancy and fetal protection. Since the consequences of HIV-infection in the immune innate system from placental microenvironment, mother, and newborn are not well understood, emphasize to investigate the strategies to potentiate the innate immune immune response. We evaluated in mononuclear cells (CMN) of peripheral blood and cord blood from HIV-1-infected pregnant and uninfected mother-cord blood the TNF-a, IL-10 and IFN-a secretion induced by agonists of extracellular Toll-like receptor (TLRs) (TLR2, TLR4 and TLR5) and agonists for intracellular TLRs (TLR7, TLR7/8, TLR9). Moreover, as checkpoint of innate immune response we evaluate the myeloid dendritic cells (mDC) and plasmacytoid DC (pDC) responsinevess to TLRs related to antiviral response (TLR7, TLR7/8 e TLR9). Were also evaluated expression of CD123, TLR8, CD14/CD16 and HLA-G of maternal samples of decidua and villi both infected by HIV-1.The results showed that HIV-1 infected mother-cord blood have a deficit in the TNF-a response induced by TLR2, TLR5, TLR3, TLR7 PBMC activation, but preserved for TLR7/8 (CL097) stimulation, mainly by the newborn cells. Moreover, only CL097 activation was efficacious to induce IL-10 and IFN-a secretion by the infected group, in both mother and cord blood cells. Up-regulation of IFN-a secretion level was achieved with CL097 by cord blood from HIV-infected mother compared to control mothers. CL097 stimulation was also able to induce Interferon-regulator factor-7, IFN-a and TNF-a mRNA expression in PBMC at similar levels between groups, confirming the potential of TLR7/8 activation. TLR7/TLR8 activation overcomes the impairment of TNF-a production by mDC, but maintained the dysfunctional type I IFN response by pDCs in HIV-infected pairs. Expression of TLR8, CD123 and HLA-G was increased in placental tissue from infected-mother compare to uninfected control. Our findings highlight the dysfunction of innate immune response in HIV-treated mother-newborn. Adjuvant potential of TLR8, in the systemic response as well as in the placental microenvironment, emphasizes the use of natural and /or synthetic TLR agonists to improve antiviral response at the maternal-fetal interface.

Mutações no gene CD40LG estão associadas à Síndrome de Hiper-IgM, relacionada ao cromossomo X, que é uma Imunodeficiência Primária. A ausência da interação CD40L/CD40 (linfócitos-DCs) acarreta um aumento da suscetibilidade às infecções fúngicas. Os efeitos do tratamento in vitro com interferon-gama em células dendríticas de pacientes com mutações no CD40L demonstraram potencial sobre a imunologia das DCs e nos remete a fundamentar possíveis ensaios clínicos futuros, que tenham por tema a prevenção e o tratamento de infecções oportunistas. / Mutations in the CD40LG gene are associated with the X-linked Hyper-IgM Syndrome, which is a Primary Immunodeficiency. The absence of the CD40L / CD40 interaction (lymphocytes-DCs) leads to increased susceptibility to fungal infections. The effects of in vitro gamma-interferon treatment on dendritic cells from patients with CD40L mutations have demonstrated potential for DC immunology and suggest that future clinical trials should address the prevention and treatment of opportunistic infections.

Células dendríticas (DCs) são células do sistema imunológico muito importantes no processo de indução de imunidade, capazes de conectar respostas imunes inata e adquirida e levar à ativação de células T e B. Recentemente demonstrou-se que é possível direcionar antígenos diretamente para as DCs in vivo através da administração de baixas doses de uma proteína recombinante híbrida fusionada a um anticorpo monoclonal específico para receptores presentes na superfície destas células. Dois dos anticorpos monoclonais utilizados tem a capacidade de ligar-se aos receptores endocíticos DEC205 e DCIR2 presentes na superfície de duas sub-populações distintas de DCs.Construiu-se anticorpos híbridos em fusão com os genes que codificam a proteína MSP-119 presente na superfície das formas merozoítas de P.yoelii e P.vivax. Ensaios de imunização mostraram que o anticorpo anti-DEC fusionado a qualquer das duas proteínas foi capaz de induzir principalmente uma resposta imune celular quando administrado na presença de diferentes adjuvantes. Já a resposta imune humoral foi modulada dependendo de várias combinações. / Dendritic cells (DCs) are cells of the immune system very important in the process of induction of immunity. They are able to connect innate and acquired immune responses and lead to activation of T and B cells. Recently it was shown that it is possible to target antigens directly to DCs in vivo by the administration of low doses of a recombinant hybrid protein consisting of a monoclonal antibody specific for receptors present on the surface of these cells fused with the antigen of interest. When these hybrid antibodies were injected in animals in the presence of a DC maturation stimulus, strong immune response against different antigens was obtained. Two of the monoclonal antibodies used have the ability to bind to either the DEC205 or the DCIR2 endocytic receptors present on the surface of two distinct DC sub-populations. In this work, we constructed hybrid antibodies fused with the sequence encoding the MSP-119 protein present on the surface P. yoelii and P. vivax merozoites. Most antibodies were successfully produced and maintained their ability to bind to their respective receptors. Immunization trials showed that the anti-DEC antibody fused to any of the two proteins was able to induce mainly a cellular immune response when administered in the presence of adjuvants. On the other hand, the humoral immune response depends of some combinations.