Exposure to Dengue Envelope Protein Domain III Induces Nlrp3 Inflammasome-Dependent Endothelial Dysfunction and Hemorrhage in Mice.

Typically occurring during secondary dengue virus (DENV) infections, dengue hemorrhagic fever (DHF) causes abnormal immune responses, as well as endothelial vascular dysfunction, for which the responsible viral factor remains unclear. During peak viremia, the plasma levels of virion-associated envelope protein domain III (EIII) increases to a point at which cell death is sufficiently induced in megakaryocytes in vitro. Thus, EIII may constitute a virulence factor for endothelial damage. In this study, we examined endothelial cell death induced by treatment with DENV and EIII in vitro. Notably, pyroptosis, the major type of endothelial cell death observed, was attenuated through treatment with Nlrp3 inflammasome inhibitors. EIII injection effectively induced endothelial abnormalities, and sequential injection of EIII and DENV-NS1 autoantibodies induced further vascular damage, liver dysfunction, thrombocytopenia, and hemorrhage, which are typical manifestations in DHF. Under the same treatments, pathophysiological changes in the Nlrp3 inflammasome-deficient mice were notably reduced compared with those in the wild-type mice. These results suggest that the Nlrp3 inflammasome constitutes a potential therapeutic target for treating DENV-induced hemorrhage in DHF.

Eficacia y seguridad de la vacuna contra el dengue / Efficacy and safety of dengue vaccine

El dengue es un problema creciente para la salud pública mundial. En Argentina, los casos se han ido incrementado en los últimos años. La vacuna Dengvaxia (CYD-TDV) fue aprobada por la Agencia Nacional de Medicamentos, Alimentos y Tecnología (ANMAT) en 2017, y actualmente está indicada para personas entre los 9 y 45 años de edad que residan enzonas endémicas. A partir de la consulta de una paciente sobre la posibilidad de vacunarse contra el dengue, la autora se plantea la pertinencia de su indicación, teniendo en cuenta la eficacia y seguridad de la vacuna. Luego de una búsqueda rápida se encontró evidencia que señala que la vacuna contra el dengue CYD-TDV mostró poca eficacia en comparación con otras vacunas disponibles en el mercado, siendo más segura y eficaz en personas que ya han sido infectadas anteriormente por el virus del dengue (sujetos seropositivos). En cambio, se observó un aumento del riesgo de dengue grave en los infectados por vez primera tras la vacunación (sujetos seronegativos). Se concluye que la estrategia recomendada consiste en vacunar únicamente a las personas que hayan tenido infección por dengue con anterioridad, consistiendo en una buena práctica la toma de decisiones compartidas con cada paciente. (AU)

Dengue is a growing problem for global public health. In Argentina, cases have been increasing in recent years. The Dengvaxia vaccine (CYD-TDV) was approved by the National Agency for Medicines, Food and Technology in 2017, and it is currently indicated for people between 9 and 45 years of age who reside in endemic areas. Based on the consultation of a patient about the possibility of being vaccinated against dengue, the author considers the relevance of its indication, taking into account the efficacy and safety of the vaccine. After a quick search, evidence was found that indicates that the CYD-TDV dengue vaccine showed little efficacy compared to other vaccines available on the market, being safer and more effective in people who have already been previously infected by the dengue virus (seropositive subjects). In contrast, an increased risk of severe dengue was observed in those infected for the first time after vaccination (seronegative subjects). It is concluded that the recommended strategy consists of vaccinating only people who have had dengue infection before, making shared decisions with each patient a good practice. (AU)

Mast cell mediators in relation to dengue severity: A systematic review and meta-analysis.

BACKGROUND: Degranulation of mast cells (MCs) releases several mediators such as vascular endothelial growth factor (VEGF), chymase, tryptase, histamine, and cytokines, which all have important roles in the severity of dengue infection. We aimed to investigate the role of MCs in severity of dengue. METHODS: We searched for relevant studies in 10 databases on 15 August 2016. Meta-analysis (MA) was conducted by R version 3.5.0. RESULTS: We included 24 studies. in vivo and in vitro studies showed higher MC products released from infected mice/cells with dengue virus. In addition, when administering MC stabilizers or antihistaminic drugs, there was a decrease in vascular/capillary permeability. In human and at early stages, studies revealed an insignificant difference in VEGF levels in dengue fever (DF) versus dengue hemorrhagic fever (DHF) (standardized mean difference [SMD] 0.145; 95% confidence interval [CI], -0.348-0.638). Meanwhile, at acute stages and compared with healthy controls, high heterogeneity with an inconclusive difference in VEGF levels were noted in DF and DHF. However, pooled serum and plasma levels of VEGF were increased significantly in dengue shock syndrome (DSS) versus healthy controls (SMD 0.65; 95% CI, 0.3-0.95). There were also significantly higher chymase levels in DHF patients compared with DF during the acute phase (MD -6.531; 95% CI, -12.2 to -0.9). CONCLUSION: VEGF and chymase levels are mediators in dengue pathogenesis. However, limited data were available to support their role in severe dengue cases. Further studies are needed to evaluate the function of other mediators in dengue severity.

Genetic variants of MICB and PLCE1 and associations with the laboratory features of dengue.

BACKGROUND: A previous genome-wide association study identified 2 susceptibility loci for severe dengue at MICB rs3132468 and PLCE1 rs3740360 and further work showed these mutations to be also associated with less severe clinical presentations. The aim of this study was to determine if these specific loci were associated with laboratory features of dengue that correlate with clinical severity with the aim of elucidating the functional basis of these genetic variants. METHODS: This was a case-only analysis of laboratory-confirmed dengue patients obtained from 2 prospective cohort studies and 1 randomised clinical trial in Vietnam (Trial registration: ISRCTN ISRCTN03147572. Registered 24th July 2012). 2742 dengue cases were successfully genotyped at MICB rs3132468 and PLCE1 rs3740360. Laboratory variables were compared between genotypes and stratified by DENV serotype. RESULTS: The analysis showed no association between MICB and PLCE1 genotype and early viraemia level, platelet nadir, white cell count nadir, or maximum haematocrit in both overall analysis and in analysis stratified by serotype. DISCUSSION: The lack of an association between genotype and viremia level may reflect the sampling procedures within the included studies. The study findings mean that the functional basis of these mutations remains unclear. TRIAL REGISTRATION: ISRCTN ISRCTN03147572 . Registered 24th July 2012.

Activation of MDL-1 (CLEC5A) on immature myeloid cells triggers lethal shock in mice.

Systemic inflammatory response syndrome (SIRS) is a potentially lethal condition, as it can progress to shock, multi-organ failure, and death. It can be triggered by infection, tissue damage, or hemorrhage. The role of tissue injury in the progression from SIRS to shock is incompletely understood. Here, we show that treatment of mice with concanavalin A (ConA) to induce liver injury triggered a G-CSF-dependent hepatic infiltration of CD11b+Gr-1+Ly6G+Ly6C+ immature myeloid cells that expressed the orphan receptor myeloid DAP12-associated lectin-1 (MDL-1; also known as CLEC5A). Activation of MDL-1 using dengue virus or an agonist MDL-1-specific antibody in the ConA-treated mice resulted in shock. The MDL-1+ cells were pathogenic, and in vivo depletion of MDL-1+ cells provided protection. Triggering MDL-1 on these cells induced production of NO and TNF-α, which were found to be elevated in the serum of treated mice and required for MDL-1-induced shock. Surprisingly, MDL-1-induced NO and TNF-α production required eNOS but not iNOS. Activation of DAP12, DAP10, Syk, PI3K, and Akt was critical for MDL-1-induced shock. In addition, Akt physically interacted with and activated eNOS. Therefore, triggering of MDL-1 on immature myeloid cells and production of NO and TNF-α may play a critical role in the pathogenesis of shock. Targeting the MDL-1/Syk/PI3K/Akt/eNOS pathway represents a potential new therapeutic strategy to prevent the progression of SIRS to shock.

Contribution of macrophage migration inhibitory factor to the pathogenesis of dengue virus infection.

Dengue fever is an emerging viral disease transmitted by arthropods to humans in tropical countries. Dengue hemorrhagic fever (DHF) is escalating in frequency and mortality rates. Here we studied the involvement of macrophage migration inhibitory factor (MIF) in dengue virus (DENV) infection and its pathogenesis. Patients with DHF had elevated plasma concentrations of MIF. Both leukocytes from these patients and macrophages from healthy donors infected in vitro with DENV showed a substantial amount of MIF within lipid droplets. The secretion of MIF by macrophages and hepatocytes required a productive infection and occurred without an increase in gene transcription or cell death, thus indicating active secretion from preformed stocks. In vivo infection of wild-type and mif-deficient (Mif(-/-)) mice demonstrated a role of MIF in dengue pathogenesis. Clinical disease was less severe in Mif(-/-) mice, and they exhibited a significant delay in lethality, lower viremia, and lower viral load in the spleen than wild-type mice. This reduction in all parameters of severity on DENV infection in Mif(-/-) mice correlated with reduced proinflammatory cytokine concentrations. These results demonstrated the contribution of MIF to the pathogenesis of dengue and pointed to a possible beneficial role of neutralizing MIF as an adjunctive therapeutic approach to treat the severe forms of the disease.

Dengue, dengue hemorrágico / Dengue, dengue haemorrhagic fever

El Dengue o Fiebre por Dengue, es una enfermedad febril producida por uno de los cuatro serotipos del virus Dengue, que pertenecen al grupo de virus transmitidos por artrópodos, arthropod-borne-virus ó arbovirus. La transmisión se hace por medio de la hembra del mosquito Aedes aegypti, que pertenece al género flavivirus de la familia flaviridae. El Dengue es la enfermedad transmitida por vectores más frecuente en todo el mundo. Desde 1993 en Costa Rica el Dengue es una enfermedad endémica en las costas del océano Pacífico y del mar Caribe. Durante estos años y hasta el 8 de septiembre del 2007 la prevalencia de Dengue Clásico es de 4.087 casos por 100000 habitantes, de Dengue Hemorrágico 14 casos por 100000 habitantes para una tasa de letalidad por dengue hemorrágico de 0.02 por ciento. Entre la inoculación del virus por la mosquita Aedes y la aparición de los síntomas hay un lapso de 3 a 14 días, en promedio 7 días. Es el período de incubación de la enfermedad. Existen 4 grupos antigénicos o serotipos de virus del Dengue: DEN-1, DEN-2, DEN-3 y DEN-4. El DEN-1 tiene sólo 7 biotipos, y el DEN-2, 34 biotipos. Las hemorragias que se producen en el Dengue son el producto de las lesiones en el endotelio vascular, de la trombocitopenia, de la disfunción de las plaquetas y de la alteración de los factores de coagulación. La lesión de las esclusas de la Zonula Occludens provoca un escape de líquidos del espacio intra-vascular al espacio extra-vascular. La hipovolemia desencadena una serie de respuestas homeostáticas que tiene como fin mantener una mejor perfusión de los órganos más nobles de la economía en detrimento de otros órganos como son la piel y los músculos. El periodo febril dura de 3 a 7 días, y el día de la defervescencia, día cero, el paciente evolucionará hacia la convalecencia o hacia el Dengue Hemorrágico. En los primeros días suele aparecer exantema generalizado, con palidez de la piel al hacer presión sobre ella. Las manos y pies se tornan hiper...

Descripción de la fiebre hemorrágica del dengue, serotipo 3, Ciudad de La Habana, 2001-2002 / Description of dengue hemorrhagic fever, serotype 3, City of Havana, 2001-2002

Introducción: el dengue es una entidad de etiología viral, que habitualmente se clasifica en 2 formas clínicas: fiebre del dengue y fiebre hemorrágica del dengue. Su agente causal posee 4 serotipos (dengue 1 al 4). Objetivos: reportar la descripción clínica y de algunos parámetros de laboratorio e imagenológicos del total de pacientes definidos como fiebre hemorrágica del dengue, comparados con un grupo de casos de fiebre dengue, ingresados en el Instituto de Medicina Tropical Pedro Kourí durante la epidemia. Métodos: se estudiaron todos los enfermos con fiebre hemorrágica del dengue y un grupo de pacientes con fiebre del dengue, ingresados durante la epidemia por dengue 3 de Ciudad de La Habana, 2001-2002. Se analizaron las variables sociodemográficas, manifestaciones clínicas, de laboratorio y ultrasonográficas. Se calculó estimación de riesgo y diferencia de proporciones. Resultados: los factores de riesgo asociados a fiebre hemorrágica del dengue fueron sexo masculino (RR 1,94; IC 95 por ciento 1,29-2,89) y asma bronquial (RR 1,68 IC 95 por ciento 1,11-2,55). Las manifestaciones que predominaron en dicha forma clínica fueron vómitos, dolor abdominal, astenia y anorexia. El laboratorio y el ultrasonido fueron útiles para diferenciar el grado de severidad del cuadro clínico. Conclusiones: los hallazgos contribuyen al conocimiento de aspectos clínicos del dengue, serotipo 3.

Introduction: Dengue is often classified into two clinical presentations: dengue fever and dengue hemorrhagic fever. The disease is caused by any of four dengue virus serotypes (dengue 1 to 4). Objectives: To report the clinical description and some of lab and imaging indications found in all the patients defined as dengue hemorrhagic fever cases and to compare them with those of a group of dengue fever cases admitted to Pedro Kourí Institute of Tropical Medicine during the epidemic. Methods: All dengue hemorrhagic fever cases and a group of dengue fever patients, admitted to Pedro Kourí Institute during dengue 3 epidemic occurred in the City of Havana from 2001 to 2002, were studied. Demographic characteristics, clinical manifestations and laboratory and ultrasonographic findings were analyzed. Risk estimation and ratio differences were calculated. RESULTS: The risk factors associated to dengue hemorrhagic fever were male sex (RR 1.94; CI 95 por ciento 1.29-2.89) and bronchial asthma (RR 1.68 CI 95 por ciento 1.11-2.55). Vomiting, abdominal pain, asthenia and anorexia were more frequent in patients with hemorrhagic fever. Clinical laboratory and ultrasound were useful tools for determining the level of severity of the clinical picture. Conclusions: These findings lead to a better understanding of the clinical aspects of dengue 3 virus.

Caracterización clínica del dengue hemorrágico en niños / Clinical features of hemorrhagic dengue in children

Objetivos: Determinar los síntomas presentes al ingreso que predicen evolución a dengue hemorrágico. Material y métodos: Se realizó un estudio de casos y controles de 88 pacientes ingresados en el servicio de pediatría del Hospital "Dr. Enrique Baltodano" de Liberia en el año 2003. Los pacientes incluidos en el estudio tuvieron serología positiva IgM al egreso. Se realizó la fase descriptiva sexo, edad y posteriormente un análisis multivariado de las variables clínicas asociadas con evolución a dengue hemorrágico. Resultados: De los 88 pacientes, 22 evolucionaron a dengue hemorrágico y 66 a dengue clásico. 39.8 por ciento (n igual 35) masculinos, 60.2 por ciento (n igual 53) femeninos. La edad promedio en años 5.2 años los dengues hemorrágicos y 7.7 años los dengues clásicos. La estancia promedio en días: 4 para los diagnosticados por dengue hemorrágico y 2.7 los diagnosticados con dengue clásicos. Dolor abdominal y dolor retroocular son los predictores independientes de dengue hemorrágico en niños. Los hallazgos de ultrasonido fueron ascitis en 45 por ciento (n igual 10) y 55 por ciento (n igual 12) además de ascitis, derrame pleural y edema de vesícula. Conclusiones: Dolor abdominal y retroocular detectados al ingreso son los predictores independientes de dengue hemorrágico.

Fiebre amarilla: la enfermedad recurrente: a propósito de un caso / Yellow fever: the recurrent disease: a purpose of a case

La fiebre amarilla es una enfermedad infecciosa producida por arbovirus que origina compromisos hepático, hemorrágico y renal, frecuentemente fatales. Tiene dos patrones de transmisión, el urbano, generalmente epidémico y el selvático de presentación esporádica o pequeños brotes. Esta enfermedad es una de las grandes plagas de la historia de la humanidad; durante siglos azotó a los habitantes y colonizadores del Africa y la América tropical. A mediados de este siglo la enfermedad disminuyó su incidencia con las campañas de erradiación del vector y la introducción de la vacunación en 1934. Actualmente se informan entre 1000 y 3000 casos anuales, un 10 por ciento de los cuales tiene lugar en Centro y Sudamérica. No existen antivirales efectivos disponibles para esta enfermedad. La fiebre amarilla es difícil de identificar durante las etapas tempranas, ya que puede confundirse fácilmente con malaria, fiebre tifoidea, fiebre viral hemorrágica, leptospirosis y hepatitis viral. El tratamiento es sintomático y de sostén. La fiebre amarilla puede prevenirse con la vacunación. El caso que se presenta a continuación es un paciente masculino de 19 años que consulta por presentar fiebre, evacuaciones líquidas, cefalea y epistaxis, teniendo antecedentes apidemiológicos y familiares importantes, el cual fue tratado desde el comienzo de su ingreso como un Síndrome Icterohemorrágico, al no tener un diagnóstico bien establecido, el cual se obtuvo al egresado el paciente mediante resultados serológicos positivos para fiebre amarilla (1,2).

Transient CD4/CD8 ratio inversion and aberrant immune activation during dengue virus infection.

The immune status after dengue virus infection was studied in dengue patients from an outbreak of serotype 3 dengue virus infection in the southern part of Taiwan during November and December 1998. Consecutive blood samples from 29 dengue patients, of whom 21 had dengue fever and 8 had dengue hemorrhagic fever/dengue shock syndrome, were collected, and the immunophenotypes of the peripheral blood mononuclear cells were determined by flow cytometry. The early activation marker CD69 appeared on lymphocytes and monocytes at day 4 after the onset of fever, and declined afterward. However, a transient reverse in the CD4/CD8 ratio occurred at days 6-10 after the onset of fever. The CD4/CD8 ratio inversion was manifested in 10 of 29 dengue patients and was encountered more frequently in dengue hemorrhagic fever/dengue shock syndrome than in dengue fever patients. Analysis of the clinical blood cell count of these 10 cases showed that increase of immature neutrophils developed at fever days 5-6, CD4(dim) or CD8(dim) monocytosis at days 6-7, and atypical lymphocytosis at days 8-10 after the onset of fever. Serum IL-6 was found at either day 7 or day 9-11. The PHA-stimulated T-cell response was depressed as well. These changes in immune parameters indicate aberrant immune activation during dengue virus infection and might be involved in the pathogenesis of dengue virus infection.

Dengue-specific T cell responses in peripheral blood mononuclear cells obtained prior to secondary dengue virus infections in Thai schoolchildren.

Children who experience secondary dengue virus (DV) infections are at increased risk for dengue hemorrhagic fever. To study the effect of preexisting T cell responses to DV on the severity of secondary virus infection, peripheral blood mononuclear cells (PBMC) from 10 subsequently hospitalized and 12 nonhospitalized Thai schoolchildren were stimulated with inactivated dengue antigens, and proliferation of interferon (IFN)-gamma or tumor necrosis factor (TNF)-alpha responses of the preinfection PBMC were measured. Proliferation responses were observed in 11 subjects, and IFN-gamma responses were seen in 12 subjects, 6 of whom showed broad serotype cross-reactive IFN-gamma responses. TNF-alpha responses were detected exclusively in 4 hospitalized subjects. Four PBMC samples that showed neither proliferation nor cytokine responses to any dengue antigen were from nonhospitalized subjects. This study, thought to be the first to investigate T cell responses to DV in preinfection PBMC, suggests that the pattern of preexisting T cell responses influences the risk for severe disease.

Dengue hemorrágica / Dengue haemorrhagic fever

A dengue hemorrágica/síndrome do choque da dengue (DH/SCD) é uma arbovirose de notificaçäo compulsória provocada por um vírus da família Flavovirae que apresenta quatro subtipos. É transmitida principalmente pelo mosquito Aedes aegypti. Ela se caracteriza por uma febre alta de início repentino, trombocitopenia, hemoconcentraçäo, exudaçäo de plasma, tendência ao choque e às manifestaçöes hemorrágicas. Outros sintomas como artralgia, mialgia e dor retrocular também podem ocorrer. Sua principal hipótese de ocorrência é uma reinfecçäo por um vírus, heteróloga, ou seja, é uma infecçäo secundária por um vírus diferente da primeira infecçäo. Atinge principalmente crianças, asiáticos e caucasianos e é endêmica em alguns países do mundo, principalmente no sudeste asiático. Pode, na ocorrência de choque, levar ao óbito entre 12 a 24 horas. Por isso, o diagnóstico rápido e preciso é indispensável, consistindo basicamente na anamnese, exame físico e exames laboratoriais como o hemograma. Na clínica, devem ser observados sinais de aumento da permeabilidade vascular. No choque pode ocorrer bradicardia. O trratamento se dá basicamente através da infusäo de soro e a prevençäo deve ser feita, principalmente combatendo o mosquito (com a eliminaçäo de criadouros, pulverizaçöes, uso de larvicidas) e através de vacinas; contudo estas ainda estäo em estudo.(au)

Dengue hemorrágico emergencia pediátrica en el Huila

El dengue hemorrágico (DH) hizo su aparición en el Huila en 1992, desarrollándose la primera epidemia con 125 casos, la mayoría de éstos, en niños. El impacto en la población infantil ha sido evidente y persistente hasta hoy, cuando vivimos el segundo brote con 246 niños afectados, encontrando una mortalidad del 4.5 por ciento. Para observar las características clínicas de los pacientes con DH en esta segunda epidemia, se realizó un estudio prospectivo, descriptivo; se tuvieron en cuenta todos los niños hospitalizados en dos grandes instituciones asistenciales de Neiva, con diagnóstico clínico y comprobación serológica de DH en el año de 1997. En el 72 por ciento de los pacientes afectados, los síntomas se localizaron en el abdomen consistentes en: dolor intenso y progresivo, vómito, hepatomegalia y ascitis. Algunos casos asociados a hemorragia del tracto gastrointestinal. Un hecho importante, relacionado con la severidad del estado clínico fue la presencia, tiempo de instauración y severidad de derrames serosos (pleurales, peritoneales y pericárdicos) en el 40 por ciento de los casos. Estos derrames, se instauraron rápidamente, lo cual es reflejo de la severidad de la fuga vascular, llevando incluso al 30 por ciento de los pacientes a Shock Dengue Hemorrágico (SSD). 45 casos se presentaron en niños menores de dos años, lo que representa el 19 por ciento de los niños con DH. Sin embargo, el 50 por ciento de los niños que murieron, correspondieron a este grupo de edad. En conclusión, nos enfrentamos a una segunda epidemia considerablemente más severa por el mayor número de pacientes afectados, más casos de shock, lo que pudo estar relacionado con la virulencia del serotipo viral circulante. Los hallazgos abdominales se convirtieron en datos cardinales para el pronóstico ya que, sobre todo, la velocidad y la severidad con la que se se instauraron estos signos fueron predictivos de shock y complicaciones fatales.

Pathophysiologic and prognostic role of cytokines in dengue hemorrhagic fever.

Dengue shock syndrome is a severe complication of dengue hemorrhagic fever (DHF), characterized by a massive increase in vascular permeability. Plasma cytokine concentrations were prospectively studied in 443 Vietnamese children with DHF, of whom 6 died. Shock was present in 188 children on admission to hospital, and in 71 children it developed later. Contrary to expectations, certain inflammatory markers (interleukin-6 and soluble intercellular adhesion molecule-1) were lower in the group with shock, and this may reflect the general loss of protein from the circulation due to capillary leakage. Only soluble tumor necrosis factor receptor (TNFR) levels showed a consistent positive relationship with disease severity. In patients with suspected DHF without shock, admission levels of sTNFR-75 in excess of 55 pg/mL predicted the subsequent development of shock, with a relative risk of 5.5 (95% confidence interval, 2.3-13.2). Large-scale release of soluble TNFR may be an early and specific marker of the endothelial changes that cause dengue shock syndrome.