Cell death is an imperative mechanism for the development, homeostasis and survival of an organism. Various forms of cell death have been documented and recent reports indicate that the mode of cell death elicited can have a profound influence on the development and perpetuation of inflammation. Apoptosis is the predominant, programmed pathway of cell death, which ensures physiological elimination of unwanted cells. On the other hand, another cell death pathway described as programmed necrosis (necroptosis), has recently been revealed. The induction of necroptosis and its impact in host biology is not clear. Herein I have evaluated the mechanisms of necroptosis in macrophages, an important cell type of the immune system. My experiments indicate that type I interferon (IFN-I) signaling through transcription factors STAT1, STAT2 and IRF9, collectively described as the ISGF3 complex, is indispensable for necroptosis of macrophages. Furthermore, my results indicate that IFN-I signaling promotes the sustained phosphorylation of receptor interacting protein kinase 3 (Rip3), a key protein required for the execution of necroptosis. My findings also reveal that dynamin-dependent endocytosis following IFNβ stimulation and caspase inhibition is necessary for the induction of necroptosis. The results presented in this thesis provide new insights into the molecular mechanisms of necroptosis and therefore contribute to a deeper understanding of multiple inflammatory pathologies.

An in vitro IgG secretion assay was developed to investigate the regulation of the humoral immune response in humans. Pokeweed mitogen (PWM), a plant lectin derived from Phytolacca americana stimulates human peripheral blood mononuclear cells (PBMNC) to divide and resting B-lymphocytes to differentiate into immunoglobulin secreting cells (ISC). This differentiation requires that both monocytes and T-lymphocytes be present in the culture system. The amount of IgG secreted by these differentiated B-lymphocytes in response to PWM appears to be the net result of a balance between the functional activity of the regulatory T-helper and T-suppressor cells. Alterations, qualitative or quantitative in any of these leukocyte subsets could conceivably alter the amount of IgG secreted by the B-lymphocyte subpopulation. We have employed this assay to investigate the immune status in a group of chronic progressive multiple sclerosis (MS) patients and to assess the immunoregulatory effects of interferon (Wellferon R, INF) administered in vivo to this selected group. Their mononuclear cells (MNC) were studied in this PWM induced IgG secretion assay before INF treatment and again after 7 days of daily sub-cutaneous injections (5 X 10⁶ u/day). Twenty patients received the interferon (INF) preparation and eighteen received normal saline. The study was carried out in a double blind manner and the code was broken only after individual results had been calculated. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Essential thrombocythemia (ET) is a rare myeloproliferative neoplasm affecting 43.7 out of every 100,000 people in the United States. The disease is characterized by abnormally high platelet counts, mutational abnormalities in Janus Kinase 2 (JAK2)/Calreticulin (CALR)/myeloproliferative leukemia virus oncogene (MPL), and increased megakaryocyte production and differentiation. The average age of onset for patients with ET is between 65-70 years, but recent studies have demonstrated a downward trend in the age of diagnosis. Mechanistically, ET mutations cause the dimerization of JAK and upregulation of the JAK-STAT pathways. Common treatment approaches seek to use cytoreduction and platelet inhibition to lower the risk of a thrombotic event. Hydroxyurea and low-dose aspirin have been the gold-standard of treatment for ET patients. This thesis sought to compare the current available therapy with second-line treatments and investigational treatments. Anagrelide is a key second-line treatment for ET that is used in the event of intolerance to hydroxyurea. It acts through cytoreductive mechanisms which result in a decreased platelet count. Major bleeding is a severe adverse event associated with anagrelide. Interferons are another second-line defense in the treatment of ET despite a lack of FDA approval for this indication. Interferons act directly to reduce platelet counts and, unlike other drug classes, mount an immunological response against the JAK2 stem cells to reduce the allelic burden. An immunological approach to ET may be key to the sustained treatment of the disorder without a daily dosing regimen. Despite the promise of interferons, severe adverse effects limit the adherence of many patients to this class of drugs. JAK inhibitors are an investigational drug class that acts directly through the JAK-STAT pathway. JAK inhibitors have shown little efficacy in the treatment of ET and may be better suited for treatment in combination therapies. Telomerase inhibitors are one such investigational drug class that may pair well with JAK inhibitors for the treatment of ET. All of these drug classes were compared to hydroxyurea with respect to their pharmacokinetics, pharmacodynamics, and patient evaluation. Hydroxyurea and low-dose aspirin showed superiority in comparison to other drug classes due to their low toxicity profile and minimum adverse side-effects, high oral bioavailability and wide distribution, high adherence, and production of the most uniform response to reducing thrombotic events and platelet counts. The interferon drug class shows unique potential for the treatment of ET and should be placed above the second-line treatment standard of anagrelide due to its benefits in treatment of younger and pregnant patients. Interferons are the only class of drug for the treatment of ET that did not increase the risk of drug-related leukemogenic transformations. Despite non-adherence due to side-effects and lack of an oral administration, interferons are superior to anagrelide due to their longer dosing interval and immunological attack on JAK2 stem cells. Treatment of ET with anagrelide has shown similar efficacy to hydroxyurea and interferons in platelet reduction and rivals hydroxyurea in the prevention of thrombotic risk. Despite this benefit, the risk of bleeding associated with anagrelide is a significant disadvantage. Hydroxyurea and low-dose aspirin remain the current standard of treatment for patients with ET, although new approaches may soon be available.

Conventional Dendritic cells (cDCs), a specialized group of immunological sentinels with tree-like or dendritic shapes, are critical for recognition of danger signals, presentation of antigens and control of a spectrum of innate and adaptive immune responses. Type I interferons (IFNs), as important danger signals, activate cDCs through the canonical type I IFN receptor signaling. Type I IFNs are the first line of host defense against viral infection by up-regulating IFN-stimulated genes (ISGs). However, there are circumstances in which the silencing of excessive type I IFNs could be beneficial to the host, such as IFN-dependent autoimmune diseases, gene therapy that uses viral vectors and transplantation. The role of type I IFNs in DC development, activation and antigen presentation function remains to be completely investigated. In this dissertation, we studied the regulation of Type I IFNs in murine DCs, both cDCs and plasmacytoid DCs (pDCs), and specifically we investigated the role of two molecules, Signal Transducer and Activator of Transcription 2 (STAT2) and Three prime Repair EXonuclease 1 (Trex1), in DC biology. Our research furthers our understanding of DC development, activation and function, and provides important data for the therapeutic application of modified DCs to induce immunological tolerance in gene therapy, IFN-dependent autoimmune diseases and transplantation. STAT2 is a nuclear transcription factor downstream of type I IFN receptor-mediated signaling, the role of which has been mostly explored in antiviral responses mediated by type I IFNs. However, the involvement of STAT2 in cDC activation and function such as cross-presentation remains hitherto unclear. We report that STAT2 is essential for murine cDC activation upon TLR3, -4, -7 and -9 stimulation. In the absence of STAT2, cDCs displayed impaired up-regulation of type I IFN response (costimulatory molecules and type I IFN-stimulated genes), and reduced inflammatory cytokine production when stimulated with TLR ligands. STAT2 was required in all of the DC responses to exogenous IFNα, suggesting that the canonical STAT1-STAT2 heterodimers are the major signaling transducers downstream of type I IFNs in DCs. Of interest, LPS-induced TNFα and IL6 production were reduced in STAT2-/- DCs but not in IFNAR1-/- DCs, suggesting a novel STAT2-dependent pathway mediated by LPS, bypassing type I IFN-receptor signaling. STAT2-deficient cDCs showed impaired cross-presentation leading to decreased CD8+ T cell response both in vitro and CTL killing in vivo, indicating that STAT2 is essential for TLR-induced cross-presentation. These results demonstrate that STAT2 is critical in the regulation of TLR-induced DC activation and cross-presentation, suggesting an essential role for STAT2 in anti-viral and anti-tumor immune responses. We also propose a novel regulatory function of STAT2 in the LPS response independent of type I IFN receptor signaling. Trex1 mutations are associated with a spectrum of type I IFN-dependent autoimmune diseases such as Aicardi-Goutières syndrome and systemic lupus erythematosus. Trex1 plays an essential role in preventing accumulation of excessive cytoplasmic DNA, avoiding cell-intrinsic innate DNA sensor activation and suppressing activation of both type I IFN-stimulated and IFN-independent antiviral genes. Trex1 also helps HIV escape cytoplasmic detection by DNA sensors. However, regulation of Trex1 in DC biology is lacking. We report that murine cDCs have high constitutive expression of Trex1 in vitro and in vivo in the spleen. In resting bone marrow-derived cDCs, type I IFNs up-regulate Trex1 expression via the canonical IFN receptor signaling pathway (STAT1-, STAT2-dependent). DC activation induced by TLR3, -4, -7 and -9 ligands also augments Trex1 expression through autocrine IFNß production and triggering of the IFN signaling pathway, while TLR4 ligand LPS also stimulates an early expression of Trex1 through an IFN-independent NFΚB-dependent signaling pathway. Furthermore, retroviral infection also induces Trex1 up-regulation in cDCs, as we found that a gene therapy HIV-1-based lentiviral vector induces significant Trex1 expression, suggesting that Trex1 may affect local and systemic administration of gene therapy vehicles. Our data indicate that Trex1 is induced in cDCs during activation upon IFN- and TLR- stimulation through the canonical IFN signaling pathway, and suggest that Trex1 may play a role in cDC activation during infection and autoimmunity. Finally, these results suggest that HIV-like viruses may up-regulate Trex1 to increase their ability to escape immunosurveillance. In order to dissect the role of Trex1 in DC functions, we compared DCs from Trex1-/- and wild-type mice. We report that Trex1 deficiency reduces absolute number of pDCs in BM but not in spleen of male over female mice. Furthermore, Trex1 deficiency preferentially represses Flt3L-induced DC development both in vitro and in vivo but not GM-CSF-dependent DC development, suggesting that Trex1 plays an indispensable role in Flt3L-induced DC development and GM-CSF may compensate the effect of Trex1 deficiency. This defect is only limited to male Trex1-/- DCs, and mimics the effect of mTOR inhibition. Furthermore, although Flt3L-induced Trex1-/- DCs expressed a type I IFN signature, they also exhibited decreased pDC development markers, indicating Trex1 regulates pDC development at the transcriptional level. Thus, we propose a novel and essential role of Trex1 in Flt3L-induced DC development, and the effect of Trex1 regulation is gender-dependent. Together, these findings enhance our understanding of regulatory roles of Type I IFNs in DC development, activation and function, supporting the beneficial role of STAT2/type I IFN axis in TLR-induced DC activation and cross-presentation. Our study in Trex1 reveals Trex1 induction by viral infection, type I IFNs and TLRs in DCs, and a new role of Trex1 in early development of Flt3L-induced DCs in a gender-dependent manner, whereby a balance between type I IFNs and Trex1 is important for DC activation and hemostasis. / Microbiology and Immunology

As células T CD4+ do baço são importantes na proteção frente à malária através de mecanismos mediados pelas citocinas do perfil Th1. Neste trabalho observamos o aumento das células NK1.1+TCR<font face=\"Symbol\">a<font face=\"Symbol\">b por baço nos camundongos C57BL/6, que apresentam o fenótipo de células ativadas, produzem IFN-<font face=\"Symbol\">g, expressam de níveis altos de Fas e PD-L1 que correlaciona com a baixa capacidade proliferativa na fase aguda da infecção pelo Plasmodium chabaudi AS. As células T CD4+ convencionais são a principal subpopulação de células T ativadas na resposta imune frente à infecção, que se desenvolve em duas fases consecutivas concomitantemente com as parasitemias aguda e crônica. Na fase aguda da infecção, a resposta das células T CD4+ convencionais é intensa e de curta duração, com produção grandes quantidades citocinas com cinética semelhante às células T CD4+ não-convencionais. Dessa maneira, as células T CD4+ convencionais possuem um papel central no início da resposta ao P. chabaudi, respondendo em paralelo com as células T não-convencionais como uma ponte entre a imunidade inata e adquirida. / Spleen CD4+ T cells have an important role for protection against malaria through mechanisms mediated by Th1 cytokines. We observed that the increase in NK1.1+TCR<font face=\"Symbol\">a<font face=\"Symbol\">b cell numbers per spleen in C57BL/6 mice, show an activated cell phenotype, with high expression of Fas and PD-L1 correlating with their low proliferative capacity and produce IFN-<font face=\"Symbol\">g during the acute P. chabaudi infection. We show that conventional CD4+ T cells are the main activated T cells subpopulation in the immune response to infection, which develops in two consecutive phases concomitantly with acute and chronic parasitemias. In the acute phase, the conventional CD4+ T cell response is intense and short-lasting, rapidly providing proinflammatory. Taken together, these results indicated the central role of conventional CD4+ T cells during P. chabaudi malaria, acting in parallel with non-conventional CD4+ T cells as a link between innate and acquired immunity.

Introdução: Informações de vida real relativas ao tratamento da hepatite C crônica com interferon peguilado (Peg-IFN) e ribavirina (RBV) servem para mensurar sua efetividade nos anos em que o seu uso foi amplamente difundido, além de auxiliar em tomada de decisões futuras. Objetivos: Avaliar a taxa de resposta virológica sustentada (RVS) nos pacientes com hepatite C crônica tratados com Peg-IFN e RBV, fora de protocolos de pesquisa. Determinar os fatores associados à obtenção de RVS, frequência e causas de interrupção precoce do tratamento e de redução ou interrupção temporária dos medicamentos. Métodos: Estudo observacional retrospectivo de uma coorte de pacientes de dois ambulatórios de um centro de referência brasileiro localizado em São Paulo/SP. Resultados: Dos 440 indivíduos analisados, 182 apresentaram RVS (prevalência: 41,4% [IC95%: 36,7 - 46,1]). A RVS ocorreu em 33,5% (104/310) dos pacientes com genótipo 1 e em 53,8% (7/13) e 60,5% (69/114) daqueles com genótipos 2 e 3, respectivamente. Após análise multivariada, a RVS esteve positiva e independentemente associada à presença dos genótipos 2 ou 3 (p < 0,001), ausência de esteatose (p = 0,025) e de tratamento prévio (p = 0,038). Os eventos adversos mais frequentemente relacionados à redução de dose ou suspensão temporária de Peg-IFN ou RBV foram anemia (15,6%) e plaquetopenia (3,9%). Dos eventos adversos que levaram 79 (18%) pacientes a interromper o tratamento precocemente, distúrbios psiquiátricos (15,1%) e anemia (13,9%) foram os mais frequentes. Conclusões: A taxa de RVS foi semelhante àquela obtida em outros estudos de vida real. A RVS esteve independentemente associada à: presença dos genótipos 2 ou 3, ausência de esteatose e ausência de tratamento prévio. As principais causas de redução de dose dos medicamentos foram anemia e plaquetopenia e de interrupção precoce do tratamento, desordens psiquiátricas, e citopenias / Introduction: The association of pegylated interferon (Peg-IFN) and ribavirin (RBV) was considered a first line treatment for chronic hepatitis C during the past decade. Routine clinical practice information and real-life treatment outcomes can guide future therapeutic strategies for this group of patients. Objectives: The main objective of our study was to determine the sustained virological response (SVR) rate under current clinical practice. The secondary objectives were: 1- to investigate the factors that before or during treatment could predict SVR 2- to identify the causes of treatment interruption. Method: This cross-sectional study enrolled hepatitis C patients treated with Peg-IFN and RBV in a tertiary outpatient clinic setting. Data were collected retrospectively on patients treated for hepatitis C. Demographics, treatment outcomes and potential predictors of outcome were recorded. Results: Among the 440 analyzed patients 182 achieved SVR (prevalence: 41.4% [95% CI: 36.7 to 46.1]). On an intention-to-treat basis, SVR rates were 33.5% (104/310), 53.8% (7/13) and 60.5% (69/114) in genotypes 1, 2 and 3 respectively. After multivariate analysis, SVR was independently associated with presence of genotypes 2 or 3 (p < 0.001), no hepatic steatosis (p=0.025) and absence of prior treatment (p = 0.038). Anemia (15.6%) and thrombocytopenia (3.9%) were the most frequent causes of treatment dose reduction. Among the adverse events that led 79 patients into treatment discontinuation, the most frequent were psychiatric complications (15.1%) and anemia (13.9%). Conclusion: In our cohort, the treatment success rate (SVR) was similar to that observed in other in real-life setting studies. The SVR was independently associated with: presence of genotypes 2 or 3, no hepatic steatosis and absence of prior treatment. Psychiatric disorders and anemia were the main causes of premature treatment discontinuation

A transmissão vertical mãe-recém-nato é a principal fonte de infecção pediátrica. O tratamento antirretroviral vem reduzindo a transmissão vertical, mas também tem elevado o número de infantes expostos não infectados, os quais vêm mostrando maior risco de morbidade e mortalidade. Este dado salienta a importância de avaliar as características imunológicas, relacionadas à resposta inata no binômio mãe e recém-nato. A proposta do trabalho foi avaliar a expressão de fatores antivirais em células mononucleares (CMN), tecido placentário e no colostro de mães infectadas por HIV e cordão umbilical (RN), comparadas com mães-RN controle não infectadas. Os dados mostram que há uma ativa expressão dos fatores antivirais, sejam constitutivos ou induzíveis por IFN, nas mães infectadas por HIV e nos RN expostos. No sítio de interface materno-fetal, decídua e face fetal da placenta, foi detectado um perfil alterado de expressão dos fatores antivirais, especialmente da proteína APOBEC3G. Apesar da relativa imaturidade imunológica dos RNs, a infecção materna por HIV gerou um perfil semelhante de expressão dos fatores antivirais nos RN, por uma complexa interação de fatores relacionados a gestação e a infecção. / Vertical transmission mother-newborn is the main source of pediatric infection. The antiretroviral therapy has reduced vertical transmission, but also has increased the number of exposed uninfected infants, which have shown increased risk of morbidity and mortality. This finding emphasizes the importance of evaluating the immunological characteristics, related to innate response in both the mother and newborn. The purpose of this study was to evaluate the expression of antiviral factors in mononuclear cells (MNC), placental tissue and colostrum of HIV-infected mothers and umbilical cord (RN), compared with control mothers-uninfected infants. The data show that the active expression of antiviral factors, are constitutive or inducible by IFN in HIV-infected mothers and newborns exposed. At the site of maternal-fetal interface, decidua and placental villi, a profile was detected altered expression of antiviral factors, especially the APOBEC3G protein. Despite the relative immunological immaturity of the newborn, maternal HIV infection generated a similar profile of expression of antiviral factors in RN, by a complex interaction of factors related to pregnancy and infection.

A inibição da secreção pulsátil de prostaglandina F2alfa (PGF2&alpha;) uterina (atividade antiluteolítica) pela ação do interferon-tau (IFN-&tau;) trofoblástico, mantêm a secreção de progesterona pelo corpo lúteo, fundamental ao estabelecimento da gestação nas fêmeas bovinas. Supõe-se que essa atividade antiluteolítica esteja presente no microambiente uterino bovino, portanto objetivou-se estudá-la. Dada à inexistência de ensaios que meçam especificamente a atividade antiluteolítica propôs-se elaborar um ensaio biológico para tal. Observou-se que células BEND tratadas com forbol 12,13 dibutirato (PdBu) por 6 horas em cultivo sintetizam PGF2&alpha; e tal síntese é inibida na presença de interferon-tau recombinante bovino (rbIFN-&tau;). Em outro estudo definiu-se que 25 ng/mL de PdBu promove estímulo consistente à síntese de PGF2&alpha;. A partir da análise de regressão do percentual de inibição à síntese de PGF2&alpha; estimulada por PdBu, em função da concentração de interferon-tau recombinante (rbIFN-&tau;), calculou-se a concentração de rbIFN-&tau; que inibiu em 50% a síntese máxima de PGF2&alpha; (observada na presença apenas de PdBu). Definiu-se a atividade antiluteolítica como o recíproco da concentração proteica requerida para atingir esse percentual de inibição (50%), e que a solução com uma unidade antiluteolítica é aquela que com um micrograma exerça tal efeito. Caracterizou-se a utilização dessa isoforma como padrão do ensaio antiluteolítico e calculou-se a atividade antiluteolítica do mesmo, 9,61 x 10&sup2; UA/&micro;g de proteína. Em estudo seguinte observou-se a modulação da síntese de PGF2&alpha; estimulada por PdBu, em função da concentração proteica de um pool de lavados uterinos ou meios condicionados por conceptos obtidos no décimo sétimo dia de gestação. Notou-se que para cada fluido testado há um intervalo de concentrações onde observa-se aumento linear na atividade antiluteolítica em função do acréscimo proteico. A partir da análise por regressão linear desse evento calculou-se a atividade antiluteolítica de cada amostra. Para o pool de lavados uterinos calculou-se 1,63 x 10-&sup1; UA/ &micro;g de proteína, e para o pool de meios condicionados por conceptos 1,66 x 10&sup2; UA/&micro;g de proteína. Estes estudos permitiram desenvolver uma metodologia para observar a atividade antiluteolítica em humores biológicos. Aplicando o ensaio antiluteolítico estudou-se a atividade antiluteolítica presente em lavados uterinos obtidos durante o período crítico de fêmeas bovinas prenhes ou cíclicas ( respectivamente, 56,2 e 33,9 UA/&micro;g de proteina), notou-se que a atividade antiluteolítica foi maior no microambiente uterino de fêmeas gestantes. Tal resultado associado à potente atividade antiluteolítica observada para os meios condicionados por conceptos indicam a participação do IFN-&tau; secretado pelo concepto na modulação da síntese de PGF2&alpha;. Entretanto, observou-se atividade antiluteolítica nos lavados uterinos obtidos de fêmeas cíclicas, o que indica que a síntese de PGF2&alpha; estimulada por PdBu pode ser modulada por outras proteínas, além do IFN-&tau;. Sugere-se que a atividade antiluteolítica, observada através do ensaio biológico proposto, é resultante da atuação de fatores estimulatórios e inibitórios presentes nos humores biológicos. Conclui-se que a atividade antiluteolítica pode ser mensurada pelo ensaio biológico proposto, no entanto outros estudos devem ser conduzidos para correlacionar essa atividade com a atuação do IFN-&tau;. / The inhibition of pulsatile secretion of PGF2&alpha; mediated by interferon-tau (IFN) is fundamental on the maternal recognition of pregnancy, maintaining the progesterone secretion by corpus luteum. Therefore the measurement of interferon activity in the uterine microenvironment was studied. Due to a lack of assays those measure specific antiluteolytic capacities we suggest develop a biological assay for it. In this research we observed that BEND cells treated with PdBu synthesize PGF2&alpha;, wich is inhibited by the presence of recombinant bovine interferon-tau (rbIFN-&tau;). Following we defined 25ng/mL as PdBu (phorbol 12,13 dibutirate) stimulus at the PGF2&alpha; synthesis to be applied in this biological assay. Studies about the modulation of PdBu-stimulated PGF2&alpha; synthesis by the rbIFN-&tau; validate the use of this isoform as a reference, defining a standard-curve and allowing estimating the antiluteolytic activity of 9.61 x 10&sup2; antiluteolytic units per microgram (UA/&micro;g) of protein. Further, we observed the modulation of PdBu-stimulated PGF2&alpha; synthesis exerted by a pool of uterine flushings or conceptus conditioned medium, and for each tested fluid, there is a range of concentrations where is observed an increasing rate on the inhibition of PGF2&alpha; synthesis. A restrict analysis on this concentrations range shows a linear behavior and allow calculate the antiluteolytic activity of each sample1.63 x 10-&sup1; UA/ &micro;g of protein from a pool of uterine flushings, and 1.66 x 10&sup2; UA/&micro;g from conceptus conditioned medium. These studies validated a method to observe the antiluteolytic activity from biological fluids. Using the antiluteolytic assay, we studied the antiluteolytic activity present in uterine flushings obtained during the critic period by pregnant or cyclic bovine females cíclicas (respectively 56,2 e 33,9 UA/&micro;g of protein). We observed higher antiluteolytic activity from pregnant uterine microenvironment than in cyclic uterine microenvironment. This result linked with the high antiluteolytic activity observed to conceptus conditioned medium, suggest the participation of IFN-&tau; secreted by the conceptus in the PGF2&alpha; synthesis modulation. However, we observed the antiluteolytic activity in uterine flushing obtained by cyclic cows, suggesting that the PGF2&alpha; synthesis could be modulated by another proteins. We believe that the antiluteolytic activity, observed by the antiluteolytic assay, ensue the action of inhibitors or stimulators factors in the biological fluids. We conclude that the antiluteolytic assay could be measured by the proposed biological assay, nevertheless another studies must be done in order to correlate this activity with the interferon action.

Introdução: Informações de vida real relativas ao tratamento da hepatite C crônica com interferon peguilado (Peg-IFN) e ribavirina (RBV) servem para mensurar sua efetividade nos anos em que o seu uso foi amplamente difundido, além de auxiliar em tomada de decisões futuras. Objetivos: Avaliar a taxa de resposta virológica sustentada (RVS) nos pacientes com hepatite C crônica tratados com Peg-IFN e RBV, fora de protocolos de pesquisa. Determinar os fatores associados à obtenção de RVS, frequência e causas de interrupção precoce do tratamento e de redução ou interrupção temporária dos medicamentos. Métodos: Estudo observacional retrospectivo de uma coorte de pacientes de dois ambulatórios de um centro de referência brasileiro localizado em São Paulo/SP. Resultados: Dos 440 indivíduos analisados, 182 apresentaram RVS (prevalência: 41,4% [IC95%: 36,7 - 46,1]). A RVS ocorreu em 33,5% (104/310) dos pacientes com genótipo 1 e em 53,8% (7/13) e 60,5% (69/114) daqueles com genótipos 2 e 3, respectivamente. Após análise multivariada, a RVS esteve positiva e independentemente associada à presença dos genótipos 2 ou 3 (p < 0,001), ausência de esteatose (p = 0,025) e de tratamento prévio (p = 0,038). Os eventos adversos mais frequentemente relacionados à redução de dose ou suspensão temporária de Peg-IFN ou RBV foram anemia (15,6%) e plaquetopenia (3,9%). Dos eventos adversos que levaram 79 (18%) pacientes a interromper o tratamento precocemente, distúrbios psiquiátricos (15,1%) e anemia (13,9%) foram os mais frequentes. Conclusões: A taxa de RVS foi semelhante àquela obtida em outros estudos de vida real. A RVS esteve independentemente associada à: presença dos genótipos 2 ou 3, ausência de esteatose e ausência de tratamento prévio. As principais causas de redução de dose dos medicamentos foram anemia e plaquetopenia e de interrupção precoce do tratamento, desordens psiquiátricas, e citopenias / Introduction: The association of pegylated interferon (Peg-IFN) and ribavirin (RBV) was considered a first line treatment for chronic hepatitis C during the past decade. Routine clinical practice information and real-life treatment outcomes can guide future therapeutic strategies for this group of patients. Objectives: The main objective of our study was to determine the sustained virological response (SVR) rate under current clinical practice. The secondary objectives were: 1- to investigate the factors that before or during treatment could predict SVR 2- to identify the causes of treatment interruption. Method: This cross-sectional study enrolled hepatitis C patients treated with Peg-IFN and RBV in a tertiary outpatient clinic setting. Data were collected retrospectively on patients treated for hepatitis C. Demographics, treatment outcomes and potential predictors of outcome were recorded. Results: Among the 440 analyzed patients 182 achieved SVR (prevalence: 41.4% [95% CI: 36.7 to 46.1]). On an intention-to-treat basis, SVR rates were 33.5% (104/310), 53.8% (7/13) and 60.5% (69/114) in genotypes 1, 2 and 3 respectively. After multivariate analysis, SVR was independently associated with presence of genotypes 2 or 3 (p < 0.001), no hepatic steatosis (p=0.025) and absence of prior treatment (p = 0.038). Anemia (15.6%) and thrombocytopenia (3.9%) were the most frequent causes of treatment dose reduction. Among the adverse events that led 79 patients into treatment discontinuation, the most frequent were psychiatric complications (15.1%) and anemia (13.9%). Conclusion: In our cohort, the treatment success rate (SVR) was similar to that observed in other in real-life setting studies. The SVR was independently associated with: presence of genotypes 2 or 3, no hepatic steatosis and absence of prior treatment. Psychiatric disorders and anemia were the main causes of premature treatment discontinuation

As células T CD4+ do baço são importantes na proteção frente à malária através de mecanismos mediados pelas citocinas do perfil Th1. Neste trabalho observamos o aumento das células NK1.1+TCR<font face=\"Symbol\">a<font face=\"Symbol\">b por baço nos camundongos C57BL/6, que apresentam o fenótipo de células ativadas, produzem IFN-<font face=\"Symbol\">g, expressam de níveis altos de Fas e PD-L1 que correlaciona com a baixa capacidade proliferativa na fase aguda da infecção pelo Plasmodium chabaudi AS. As células T CD4+ convencionais são a principal subpopulação de células T ativadas na resposta imune frente à infecção, que se desenvolve em duas fases consecutivas concomitantemente com as parasitemias aguda e crônica. Na fase aguda da infecção, a resposta das células T CD4+ convencionais é intensa e de curta duração, com produção grandes quantidades citocinas com cinética semelhante às células T CD4+ não-convencionais. Dessa maneira, as células T CD4+ convencionais possuem um papel central no início da resposta ao P. chabaudi, respondendo em paralelo com as células T não-convencionais como uma ponte entre a imunidade inata e adquirida. / Spleen CD4+ T cells have an important role for protection against malaria through mechanisms mediated by Th1 cytokines. We observed that the increase in NK1.1+TCR<font face=\"Symbol\">a<font face=\"Symbol\">b cell numbers per spleen in C57BL/6 mice, show an activated cell phenotype, with high expression of Fas and PD-L1 correlating with their low proliferative capacity and produce IFN-<font face=\"Symbol\">g during the acute P. chabaudi infection. We show that conventional CD4+ T cells are the main activated T cells subpopulation in the immune response to infection, which develops in two consecutive phases concomitantly with acute and chronic parasitemias. In the acute phase, the conventional CD4+ T cell response is intense and short-lasting, rapidly providing proinflammatory. Taken together, these results indicated the central role of conventional CD4+ T cells during P. chabaudi malaria, acting in parallel with non-conventional CD4+ T cells as a link between innate and acquired immunity.