Endothelial dysfunction in dengue virus pathology

The gut microbiome as a modulator of arterial function and age-related arterial dysfunction

The arterial system is integral to the proper function of all other organs and tissues. Arterial function is impaired with aging, and arterial dysfunction contributes to the development of numerous age-related diseases, including cardiovascular diseases. The gut microbiome has emerged as an important regulator of both normal host physiological function and impairments in function with aging. The purpose of this review is to summarize more recently published literature demonstrating the role of the gut microbiome in supporting normal arterial development and function and in modulating arterial dysfunction with aging in the absence of overt disease. The gut microbiome can be altered due to a variety of exposures, including physiological aging processes. We explore mechanisms by which the gut microbiome may contribute to age-related arterial dysfunction, with a focus on changes in various gut microbiome-related compounds in circulation. In addition, we discuss how modulating circulating levels of these compounds may be a viable therapeutic approach for improving artery function with aging. Finally, we identify and discuss various experimental considerations and research gaps/areas of future research.

Extracellular Vesicles in Flaviviridae Pathogenesis: Their Roles in Viral Transmission, Immune Evasion, and Inflammation

The members of the Flaviviridae family are becoming an emerging threat for public health, causing an increasing number of infections each year and requiring effective treatment. The consequences of these infections can be severe and include liver inflammation with subsequent carcinogenesis, endothelial damage with hemorrhage, neuroinflammation, and, in some cases, death. The mechanisms of Flaviviridae pathogenesis are being actively investigated, but there are still many gaps in their understanding. Extracellular vesicles may play important roles in these mechanisms, and, therefore, this topic deserves detailed research. Recent data have revealed the involvement of extracellular vesicles in steps of Flaviviridae pathogenesis such as transmission, immune evasion, and inflammation, which is critical for disease establishment. This review covers recent papers on the roles of extracellular vesicles in the pathogenesis of Flaviviridae and includes examples of clinical applications of the accumulated data.

Prothymosin α accelerates dengue virus-induced thrombocytopenia

Thrombocytopenia is the hallmark finding in dengue virus (DENV) infection. Prothymosin α (ProT) has both intracellular and extracellular functions involved in cell cycle progression, cell differentiation, gene regulation, oxidative stress response, and immunomodulation. In this study, we found that ProT levels were elevated in dengue patient sera as well as DENV-infected megakaryoblasts and their culture supernatants. ProT transgenic mice had reduced platelet counts with prolonged bleeding times. Upon treatment with DENV plus anti-CD41 antibody, they exhibited severe skin hemorrhage. Furthermore, overexpression of ProT suppressed megakaryocyte differentiation. Infection with DENV inhibited miR-126 expression, upregulated DNA (cytosine-5)-methyltransferase 1 (DNMT1), downregulated GATA-1, and increased ProT expression. Upregulation of ProT led to Nrf2 activation and reduced reactive oxygen species production, thereby suppressing megakaryopoiesis. We report the pathophysiological role of ProT in DENV infection and propose an involvement of the miR-126-DNMT1-GATA-1-ProT-Nrf2 signaling axis in DENV-induced thrombocytopenia.

The expression of circulating hsa-miR-126-3p in dengue-infected Thai pediatric patients

Circulating hsa-miRNA-126 (CmiR-126) has been reported to involve in the pathogenesis of many infectious diseases including dengue virus infection. However, no prior study has been conducted to describe more details in dengue-infected pediatric patients. This study aimed to describe CmiR-126-3p in dengue-infected pediatric patients during the febrile and convalescent phases. Additionally, the correlations between CmiR-126-3p and other relevant clinical laboratory factors were investigated. Sixty paired-serum specimens collected during febrile and convalescent phases were retrieved from patients with dengue fever (DF) (n = 30) and dengue hemorrhagic fever (DHF) (n = 30). Thirty paired-serum specimens collected from non-dengue acute febrile illness patients (AFI) were included as the control group. CmiR-126-3p was determined using reverse transcription quantitative real-time polymerase-chain reaction (RT-qPCR). Relative miRNA expression was calculated as 2^-ΔCt using CmiR-16-5p for data normalization. CmiR-126-3p expression during febrile and convalescent phases in dengue-infected patients was significantly lower than AFI (p < 0.05). However, miRNA levels were not different (p > 0.05) compared between DF and DHF and between primary and secondary infection. CmiR-126-3p levels in DF in the convalescent were significantly higher than in the febrile phase (p = 0.025). No association between CmiR-126-3p and hematocrit, WBC level, platelet count, WBC differential count or dengue viral load was observed (p > 0.05). The data suggest that hsa-miR-126-3p involved in pathogenesis of dengue infection and may be a promising early and late biomarker for DENV infection. However, hsa-miR-126-3p alone cannot be used as a predictor for dengue severity.

Utility of NO and H2S donating platforms in managing COVID-19: Rationale and promise

Viral infections are a continuing global burden on the human population, underscored by the ramifications of the COVID-19 pandemic. Current treatment options and supportive therapies for many viral infections are relatively limited, indicating a need for alternative therapeutic approaches. Virus-induced damage occurs through direct infection of host cells and inflammation-related changes. Severe cases of certain viral infections, including COVID-19, can lead to a hyperinflammatory response termed cytokine storm, resulting in extensive endothelial damage, thrombosis, respiratory failure, and death. Therapies targeting these complications are crucial in addition to antiviral therapies. Nitric oxide and hydrogen sulfide are two endogenous gasotransmitters that have emerged as key signaling molecules with a broad range of antiviral actions in addition to having anti-inflammatory properties and protective functions in the vasculature and respiratory system. The enhancement of endogenous nitric oxide and hydrogen sulfide levels thus holds promise for managing both early-stage and later-stage viral infections, including SARS-CoV-2. Using SARS-CoV-2 as a model for similar viral infections, here we explore the current evidence regarding nitric oxide and hydrogen sulfide's use to limit viral infection, resolve inflammation, and reduce vascular and pulmonary damage.

Endothelial Dysfunction, HMGB1, and Dengue: An Enigma to Solve

Dengue is a viral infection caused by dengue virus (DENV), which has a significant impact on public health worldwide. Although most infections are asymptomatic, a series of severe clinical manifestations such as hemorrhage and plasma leakage can occur during the severe presentation of the disease. This suggests that the virus or host immune response may affect the protective function of endothelial barriers, ultimately being considered the most relevant event in severe and fatal dengue pathogenesis. The mechanisms that induce these alterations are diverse. It has been suggested that the high mobility group box 1 protein (HMGB1) may be involved in endothelial dysfunction. This non-histone nuclear protein has different immunomodulatory activities and belongs to the alarmin group. High concentrations of HMGB1 have been detected in patients with several infectious diseases, including dengue, and it could be considered as a biomarker for the early diagnosis of dengue and a predictor of complications of the disease. This review summarizes the main features of dengue infection and describes the known causes associated with endothelial dysfunction, highlighting the involvement and possible relationship between HMGB1 and DENV.

N6-methyladenosine modification of the Aedes aegypti transcriptome and its alteration upon dengue virus infection in Aag2 cell line

The N⁶-methyladenosine (m⁶A) modification of RNA has been reported to affect viral infections. Studies have confirmed the role of m⁶A in replication of several vector-borne flaviviruses, including dengue virus (DENV), in mammalian cells. Here, we explored the role of m⁶A in DENV replication in the mosquito Aedes aegypti Aag2 cell line. We first determined the presence of m⁶A on the RNAs from mosquito cells and using methylated RNA immunoprecipitation and sequencing (MeRIP-Seq) identified m⁶A modification of the mosquito transcriptome and those that changed upon DENV infection. Depletion of m⁶A methyltransferases and the m⁶A binding protein YTHDF3 RNAs decreased the replication of DENV. In particular, we found that the Ae. aegypti ubiquitin carrier protein 9 (Ubc9) is m⁶A modified and its expression increases after DENV infection. Silencing of the gene and ectopic expression of Ubc9 led to reduced and increased DENV replication, respectively. The abundance of Ubc9 mRNA and its stability were reduced with the inhibition of m⁶A modification, implying that m⁶A modification of Ubc9 might enhance expression of the gene. We also show that the genome of DENV is m⁶A modified at five sites in mosquito cells. Altogether, this work reveals the involvement of m⁶A modification in Ae. aegypti-DENV interaction.

Analysis of m⁶A RNA modifications in the mosquito transcriptome and their changes upon dengue virus infection provides insight into the role of epigenetics in regulating viral replication in mosquitoes.

SARS-CoV-2 and dengue virus co-infection: Epidemiology, pathogenesis, diagnosis, treatment, and management

SARS-CoV-2 and dengue virus co-infection cases have been on the rise in dengue-endemic regions as coronavirus disease 2019 (COVID-19) spreads over the world, posing a threat of a co-epidemic. The risk of comorbidity in co-infection cases is greater than that of a single viral infection, which is a cause of concern. Although the pathophysiologies of the two infections are different, the viruses have comparable effects within the body, resulting in identical clinical symptoms in the case of co-infection, which adds to the complexity. Overlapping symptoms and laboratory features make proper differentiation of the infections important. However, specific biomarkers provide precise results that can be utilised to diagnose and treat a co-infection, whether it is simply COVID-19, dengue, or a co-infection. Though their treatment is distinguished, it becomes more complicated in circumstances of co-infection. As a result, regardless of whatever infection the first symptom points to, confirmation diagnosis of both COVID-19 and dengue should be mandatory, particularly in dengue-endemic regions, to prevent health deterioration in individuals treated for a single infection. There is still a scarcity of concise literature on the epidemiology, pathophysiology, diagnosis, therapy, and management of SARS-CoV-2 and dengue virus co-infection. The epidemiology of SARS-CoV-2 and dengue virus co-infection, the mechanism of pathogenesis, and the potential impact on patients are summarised in this review. The possible diagnosis with biomarkers, treatment, and management of the SARS-CoV-2 and dengue viruses are also discussed. This review will shed light on the appropriate diagnosis, treatment, and management of the patients suffering from SARS-CoV-2 and dengue virus co-infection.

Viral Endothelial Dysfunction: A Unifying Mechanism for COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly transmissible virus with significant global impact, morbidity, and mortality. The SARS-CoV-2 virus may result in widespread organ manifestations including acute respiratory distress syndrome, acute renal failure, thromboembolism, and myocarditis. Virus-induced endothelial injury may cause endothelial activation, increased permeability, inflammation, and immune response and cytokine storm. Endothelial dysfunction is a systemic disorder that is a precursor of atherosclerotic vascular disease that is associated with cardiovascular risk factors and is highly prevalent in patients with atherosclerotic cardiovascular and peripheral disease. Several studies have associated various viral infections including SARS-CoV-2 infection with inflammation, endothelial dysfunction, and subsequent innate immune response and cytokine storm. Noninvasive monitoring of endothelial function and identification of high-risk patients who may require specific therapies may have the potential to improve morbidity and mortality associated with subsequent inflammation, cytokine storm, and multiorgan involvement.

Cytokines storm in COVID-19 with dengue co-infection in pregnancy: Fatal maternal and fetal outcome

We report a 23-year-old pregnant woman who presented with acute high-grade fever, vomiting, and diarrhea for 5 days. She was first hospitalized in RSUD Tangerang-a secondary hospital based in Tangerang and were referred to Cipto Mangunkusumo General Hospital as a tertiary hospital. Initial laboratory results from previous hospital revealed leukopenia, low platelet, elevated aspartate transaminase, and alanine transaminase. Chest radiograph showed no pulmonary infiltration. Reverse transcriptase-PCR (RT-PCR) of the nasopharyngeal swab detected SARS-CoV-2, and NS1 antigen or IgM dengue-specific antibodies were positive. COVID-19 with dengue fever co-infection was diagnosed. Hemorrhagic manifestations were seen in both the mother (gum and gastrointestinal bleeding) and pregnancy (placental abruption). Patient was put on ventilator and was unfortunately lead to her death that were caused by multiorgan dysfunction failure due to co-infection of dengue and COVID-19. Both dengue and COVID-19 had similar manifestation, as it is a warning sign in pregnant patient experienced both that can lead to fatal result in mother and baby. Early diagnosis and management of co-infection is high clinical importance, especially in endemic area of dengue like Indonesia.

DENV NS1 and MMP-9 cooperate to induce vascular leakage by altering endothelial cell adhesion and tight junction

Dengue virus (DENV) is a mosquito-borne pathogen that causes a spectrum of diseases including life-threatening dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Vascular leakage is a common clinical crisis in DHF/DSS patients and highly associated with increased endothelial permeability. The presence of vascular leakage causes hypotension, circulatory failure, and disseminated intravascular coagulation as the disease progresses of DHF/DSS patients, which can lead to the death of patients. However, the mechanisms by which DENV infection caused the vascular leakage are not fully understood. This study reveals a distinct mechanism by which DENV induces endothelial permeability and vascular leakage in human endothelial cells and mice tissues. We initially show that DENV2 promotes the matrix metalloproteinase-9 (MMP-9) expression and secretion in DHF patients’ sera, peripheral blood mononuclear cells (PBMCs), and macrophages. This study further reveals that DENV non-structural protein 1 (NS1) induces MMP-9 expression through activating the nuclear factor κB (NF-κB) signaling pathway. Additionally, NS1 facilitates the MMP-9 enzymatic activity, which alters the adhesion and tight junction and vascular leakage in human endothelial cells and mouse tissues. Moreover, NS1 recruits MMP-9 to interact with β-catenin and Zona occludens protein-1/2 (ZO-1 and ZO-2) and to degrade the important adhesion and tight junction proteins, thereby inducing endothelial hyperpermeability and vascular leakage in human endothelial cells and mouse tissues. Thus, we reveal that DENV NS1 and MMP-9 cooperatively induce vascular leakage by impairing endothelial cell adhesion and tight junction, and suggest that MMP-9 may serve as a potential target for the treatment of hypovolemia in DSS/DHF patients.

DENV is the most common mosquito-transmitted viral pathogen in humans. In general, DENV-infected patients are asymptomatic or have flu-like symptoms with fever and rash. However, in severe cases of DENV infection, the diseases may progress to dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS), the leading causes of morbidity and mortality in school-age children in tropical and subtropical regions. DENV-induced vascular leakage is characterized by enhanced vascular permeability without morphological damage to the capillary endothelium. This study reveals a possible mechanism by which DENV NS1 and MMP-9 cooperatively induce vascular leakage. NS1 also recruits MMP-9 to degrade β-catenin, ZO-1, and ZO-2 that leads to intervene endothelial hyperpermeability in human endothelial cells and mouse vascular. Moreover, the authors further reveal that DENV activates NF-κB signaling pathway to induce MMP-9 expression in patients, mice, PBMC, and macrophages though NS1 protein. This study would provide new in signs into the pathogenesis of DENV infection, and suggest that MMP-9 may act as a drug target for the prevention and treatment of DENV-associated diseases.

Dengue fever as a potential cause of sickle cell intrahepatic cholestasis: A report of two cases

Sickle cell intrahepatic cholestasis is a potentially fatal syndrome characterized by jaundice, painful hepatomegaly, and organ dysfunction. Two cases of sickle cell intrahepatic cholestasis associated with dengue fever were described. Endothelial damage/dysfunction is a mechanism involved in severe hepatobiliary complications related to sickle cell diseases. However, the reasons for the lack of increase in the admission of patients with sickle cell disease having severe acute hepatobiliary complications triggered by endothelial damage/dysfunction due to dengue fever remain unknown. This study describes the first association between sickle cell intrahepatic cholestasis and dengue fever.

SARS-CoV-2 Infection Remodels the Phenotype and Promotes Angiogenesis of Primary Human Lung Endothelial Cells

SARS-CoV-2-associated acute respiratory distress syndrome (ARDS) and acute lung injury are life-threatening manifestations of severe viral infection. The pathogenic mechanisms that lead to respiratory complications, such as endothelialitis, intussusceptive angiogenesis, and vascular leakage remain unclear. In this study, by using an immunofluorescence assay and in situ RNA-hybridization, we demonstrate the capability of SARS-CoV-2 to infect human primary lung microvascular endothelial cells (HL-mECs) in the absence of cytopathic effects and release of infectious particles. Preliminary data point to the role of integrins in SARS-CoV-2 entry into HL-mECs in the absence of detectable ACE2 expression. Following infection, HL-mECs were found to release a plethora of pro-inflammatory and pro-angiogenic molecules, as assessed by microarray analyses. This conditioned microenvironment stimulated HL-mECs to acquire an angiogenic phenotype. Proteome analysis confirmed a remodeling of SARS-CoV-2-infected HL-mECs to inflammatory and angiogenic responses and highlighted the expression of antiviral molecules as annexin A6 and MX1. These results support the hypothesis of a direct role of SARS-CoV-2-infected HL-mECs in sustaining vascular dysfunction during the early phases of infection. The construction of virus-host interactomes will be instrumental to identify potential therapeutic targets for COVID-19 aimed to inhibit HL-mEC-sustained inflammation and angiogenesis upon SARS-CoV-2 infection.

Covid-19 and dengue: Double punches for dengue-endemic countries in Asia

The coronavirus disease 2019 (Covid-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is an international public health crisis with devastating effects. In particular, this pandemic has further exacerbated the burden in tropical and subtropical regions of the world, where dengue fever, caused by dengue virus (DENV), is already endemic to the population. The similar clinical manifestations shared by Covid-19 and dengue fever have raised concerns, especially in dengue-endemic countries with limited resources, leading to diagnostic challenges. In addition, cross-reactivity of the immune responses in these infections is an emerging concern, as pre-existing DENV-antibodies might potentially affect Covid-19 through antibody-dependent enhancement. In this review article, we aimed to raise the issue of Covid-19 and dengue fever misdiagnosis, not only in a clinical setting but also with regards to cross-reactivity between SARS-CoV-2 and DENV antibodies. We also have discussed the potential consequences of overlapping immunological cascades between dengue and Covid-19 on disease severity and vaccine development.

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.

Effect of the Rho GTPase inhibitor-1 on the entry of dengue serotype 2 virus into EAhy926 cells

Dengue virus (DV) is the most rapidly spreading arbovirus in the world. Our previous studies indicated that Rac1, a kind of Rho GTPase, was related with the increased vascular permeability in DV infection. However, the molecular mechanisms that regulate the activity of the Rac1 pathway during DV infection is not fully understood yet. Recently, Rho-specific guanine nucleotide dissociated inhibitors (Rho GDIs), as a pivotal upstream regulator of Rho GTPase, attract our attention. To identify the role of GDI-1 in DV2 infection, the expression of GDI in Eahy926 cells was detected. Moreover, a GDI-1 down-regulated cell line was constructed to explore the correlation between GDI-1 and Rac1 and to further evaluate the function of GDI in DV life cycle. Our results indicated that DV2 infection could up-regulate GDI-1 expression, and down-regulation of GDI enhanced the activity of Rac1. In addition, down-regulated GDI-1 significantly inhibited all steps of DV2 replication cycle. GDI-1 plays an important role in DV2 infection via negatively regulating the activation of the Rac1-actin pathway. These results not only contribute to our further understanding of the pathogenesis of severe dengue but also provide further insight into the development of antiviral drugs.

Correlation of host inflammatory cytokines and immune-related metabolites, but not viral NS1 protein, with disease severity of dengue virus infection

Severe dengue can be lethal caused by manifestations such as severe bleeding, fluid accumulation and organ impairment. This study aimed to investigate the role of dengue non-structural 1 (NS1) protein and host factors contributing to severe dengue. Electrical cell-substrate impedance sensing system was used to investigate the changes in barrier function of microvascular endothelial cells treated NS1 protein and serum samples from patients with different disease severity. Cytokines and metabolites profiles were assessed using a multiplex cytokine assay and liquid chromatography mass spectrometry respectively. The findings showed that NS1 was able to induce the loss of barrier function in microvascular endothelium in a dose dependent manner, however, the level of NS1 in serum samples did not correlate with the extent of vascular leakage induced. Further assessment of host factors revealed that cytokines such as CCL2, CCL5, CCL20 and CXCL1, as well as adhesion molecule ICAM-1, that are involved in leukocytes infiltration were expressed higher in dengue patients in comparison to healthy individuals. In addition, metabolomics study revealed the presence of deregulated metabolites involved in the phospholipid metabolism pathway in patients with severe manifestations. In conclusion, disease severity in dengue virus infection did not correlate directly with NS1 level, but instead with host factors that are involved in the regulation of junctional integrity and phospholipid metabolism. However, as the studied population was relatively small in this study, these exploratory findings should be confirmed by expanding the sample size using an independent cohort to further establish the significance of this study.

COVID-19, Renin-Angiotensin System and Endothelial Dysfunction

The newly emergent novel coronavirus disease 2019 (COVID-19) outbreak, which is caused by SARS-CoV-2 virus, has posed a serious threat to global public health and caused worldwide social and economic breakdown. Angiotensin-converting enzyme 2 (ACE2) is expressed in human vascular endothelium, respiratory epithelium, and other cell types, and is thought to be a primary mechanism of SARS-CoV-2 entry and infection. In physiological condition, ACE2 via its carboxypeptidase activity generates angiotensin fragments (Ang 1-9 and Ang 1-7), and plays an essential role in the renin-angiotensin system (RAS), which is a critical regulator of cardiovascular homeostasis. SARS-CoV-2 via its surface spike glycoprotein interacts with ACE2 and invades the host cells. Once inside the host cells, SARS-CoV-2 induces acute respiratory distress syndrome (ARDS), stimulates immune response (i.e., cytokine storm) and vascular damage. SARS-CoV-2 induced endothelial cell injury could exacerbate endothelial dysfunction, which is a hallmark of aging, hypertension, and obesity, leading to further complications. The pathophysiology of endothelial dysfunction and injury offers insights into COVID-19 associated mortality. Here we reviewed the molecular basis of SARS-CoV-2 infection, the roles of ACE2, RAS signaling, and a possible link between the pre-existing endothelial dysfunction and SARS-CoV-2 induced endothelial injury in COVID-19 associated mortality. We also surveyed the roles of cell adhesion molecules (CAMs), including CD209L/L-SIGN and CD209/DC-SIGN in SARS-CoV-2 infection and other related viruses. Understanding the molecular mechanisms of infection, the vascular damage caused by SARS-CoV-2 and pathways involved in the regulation of endothelial dysfunction could lead to new therapeutic strategies against COVID-19.

Cytokine Expression in Dengue Fever and Dengue Hemorrhagic Fever Patients with Bleeding and Severe Hepatitis

Dengue is the most common mosquito-borne flaviviral infection in the world today. Several factors contribute and act synergistically to cause severe infection. One of these is dysregulated host immunological mediators that cause transient pathophysiology during infection. These mediators act on the endothelium to increase vascular permeability, which leads to plasma leakage compromising hemodynamics and coagulopathy. We conducted a prospective study to explore the expression of pro- and anti-inflammatory cytokines and how they relate to clinical dengue manifestations, by assessing their dynamics through acute dengue infection in adults admitted to the Hospital for Tropical Diseases, Bangkok, Thailand. We performed cytokine analysis at three phases of infection for 96 hospitalized adults together with serotyping of confirmed dengue infection during the outbreaks of 2015 and 2016. The serum concentrations of seven cytokines (interleukin [IL]-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor alpha, and interferon gamma) were measured in duplicate using a commercial kit (Bio-Plex Human Cytokine Assay). In this study, the cytokine profile was suggestive of a T-helper 2 response. Most patients had secondary infection, and the levels of viremia were higher in patients with plasma leakage than those without plasma leakage. In addition, we observed that bleeding and hepatitis were associated with significantly higher levels of IL-8 during the early phases of infection. Furthermore, IL-6 levels in the early phase of infection were also elevated in bleeding patients with plasma leakage. These results suggest that IL-6 and IL-8 may act in synergy to cause bleeding in patients with plasma leakage.

Dengue virus non-structural protein 1 activates the p38 MAPK pathway to decrease barrier integrity in primary human endothelial cells

Dengue virus (DENV) causes an estimated 390 million infections worldwide annually, with severe forms of disease marked by vascular leakage. Endothelial cells (EC) are directly responsible for vascular homeostasis and are highly responsive to circulating mediators but are not commonly infected. DENV encodes seven non-structural (NS) proteins; with only one of those, NS1, secreted from infected cells and accumulating in the blood of patients. NS1 has been implicated in the pathogenesis of vascular permeability, but the mechanism is not completely understood. Here we used primary endothelial cells and an array of in vitro approaches to study the effect of NS1 in disease-relevant human ECs. Confocal microscopy demonstrated rapid NS1 internalization by ECs into endosomes with accumulation over time. Transcriptomic and pathway analysis showed significant changes in functions associated with EC homeostasis and vascular permeability. Functional significance of this activation was assessed by trans-endothelial electrical resistance and showed that NS1 induced rapid and transient loss in EC barrier function within 3 h post-treatment. To understand the molecular mechanism by which NS1 induced EC activation, we evaluated the stress-sensing p38 MAPK pathway known to be directly involved in EC permeability and inflammation. WB analysis of NS1-stimulated ECs showed clear activation of p38 MAPK and downstream effectors MAPKAPK-2 and HSP27 with chemical inhibition of the p38 MAP kinase pathway restoring barrier function. Our results suggest that DENV NS1 may be involved in the pathogenesis of severe dengue by activating the p38 MAPK in ECs, promoting increased permeability that characterizes severe disease.

Tryptophan Trimers and Tetramers Inhibit Dengue and Zika Virus Replication by Interfering with Viral Attachment Processes

Here, we report a class of tryptophan trimers and tetramers that inhibit (at low micromolar range) dengue and Zika virus infection in vitro These compounds (AL family) have three or four peripheral tryptophan moieties directly linked to a central scaffold through their amino groups; thus, their carboxylic acid groups are free and exposed to the periphery. Structure-activity relationship (SAR) studies demonstrated that the presence of extra phenyl rings with substituents other than COOH at the N1 or C2 position of the indole side chain is a requisite for the antiviral activity against both viruses. The molecules showed potent antiviral activity, with low cytotoxicity, when evaluated on different cell lines. Moreover, they were active against laboratory and clinical strains of all four serotypes of dengue virus as well as a selected group of Zika virus strains. Additional mechanistic studies performed with the two most potent compounds (AL439 and AL440) demonstrated an interaction with the viral envelope glycoprotein (domain III) of dengue 2 virus, preventing virus attachment to the host cell membrane. Since no antiviral agent is approved at the moment against these two flaviviruses, further pharmacokinetic studies with these molecules are needed for their development as future therapeutic/prophylactic drugs.

Upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in renal tissue in severe dengue in humans: Effects on endothelial activation/dysfunction

INTRODUCTION

Dengue is an important mosquito-borne disease in tropical and subtropical regions. Adhesion molecules have not been systematically characterized in the renal tissue of patients with severe dengue (SD). The objective of this study was to detect viral antigens in samples from patients that evolved with SD, correlating with the expression of ICAM-1, VCAM-1, VE-cadherin, and E-selectin to contribute to a better understanding of the pathophysiology of SD.

METHODS

Kidney specimens from patients with SD were selected according to clinical and laboratorial data and submitted to histological and immunohistochemistry analysis. A semiquantitative evaluation was performed considering positive immunostaining in 20 glomeruli.

RESULTS

Viral antigens were mainly detected in distal tubules. The intense immunostaining of VCAM-1 and ICAM-1 was observed. The expression of E-selectin was discrete, and VE-cadherin expression varied from mild to moderate. VCAM-1 was slightly intense in the glomerular capsule; the expression of ICAM-1 was diffuse. E-selectin was diffuse, and VE-cadherin varied from mild to moderate. The most frequent histological findings were glomerular congestion, mild glomerulitis, acute renal injury, and glomerular atrophy.

CONCLUSIONS

The results appear to demonstrate an imbalance between vascular endothelial permeability regulating events in renal lesions in SD. The increase in the expression of ICAM-1 and VCAM-1 is an in-situ indicator of higher permeability with a consequent influx of cells favoring the inflammation of the endothelium. These molecules are important in the pathophysiology of the disease and provide the possibility of developing new markers for the evaluation, clinical follow-up, and therapeutic response of patients with SD.

Dengue in hospitalized children with sickle cell disease: A retrospective cohort study in the French departments of America

BACKGROUND

To describe the characteristics of dengue in sickle cell children and try to identify risk factors of severity.

METHODS

In this retrospective study, we describe the evolution according to genotype (SS or SC and controls) and severity.

RESULTS AND CONCLUSIONS

From 2005 to 2013, 106 hospitalizations for dengue fever were recorded, 35 SS genotype, 35 SC and 36 without SCD or any other chronic disease. The clinical evolution was quite different. During hospitalization, SC patients were more likely to develop multiorgan failure (31.4% versus 25.7% for SS, and 0% for controls, p=0.001), or acute pulmonary complications than patients without SC sickle cell disease (14.3% versus 8.6% for SS, and 0% for controls, p=0.03). Level 3 analgesic treatment was more frequent in SC patients (22.9% versus 3% for SS, and 0% for controls, p<0.001). Patients with SC sickle cell disease had a higher proportion of severe forms of dengue (57.1% versus 37.1% for SS, and 0% for controls, p<0.001) than patients without SC sickle cell disease. Transfer in intensive care unit was required for most SC patients (22.9% versus 3% for SS, and 0% for controls, p=0.005).Fatal episodes were more frequent in SC patients than in patients without SC sickle cell disease (5 deaths versus 1 for SS and 0 for controls, p=0.02). Thirty-three patients (47.1%) were diagnosed as having severe dengue (13 SS and 20 SC). On univariate analysis, age >10 years, acute pulmonary complications, multiorgan failure, severe anemia requiring transfusion, use of antibiotic treatment, need for treatment with morphine, and longer hospital stay were statistically more frequent in severe dengue-associated cases. Multiple logistic regression analysis showed that HbSC genotype and acute pulmonary complications, were significantly associated with severe dengue. In the multivariate model, the area of the ROC curve was 0.831. Children with SC genotype, typically thought to have less severe disease, actually had a higher rate of severe dengue and death than those with SS genotype.

Inmunopatología del dengue: importancia y participación de los monocitos y sus subpoblaciones

El dengue es una infección viral aguda transmitida por la picadura de mosquitos del género Aedes, la cual produce hasta 100 millones de infecciones anuales en el mundo. Una gran proporción de individuos infectados con el virus presentan infecciones asintomáticas. Sin embargo, de los individuos que desarrollan la enfermedad, el 95 % presentan signos y síntomas similares a una virosis común, que por lo general se autoresuelven (dengue con y sin signos de alarma). El 5 % restante puede evolucionar a manifestaciones graves, caracterizadas por hemorragias, daño orgánico, choque hipovolémico e incluso la muerte (dengue grave).Los monocitos son uno de los blancos principales de la infección producida por el virus del dengue (DENV), los cuales participan en la replicación del mismo y en la producción de una gran variedad de citoquinas que contribuyen con el daño de diferentes tejidos y órganos en respuesta a la infección. Los monocitos se dividen en tres subpoblaciones: clásica (CD14++CD16-), no clásica (CD14+CD16++) e intermedia (CD14++CD16+), las cuales poseen respuestas funcionales contrastantes en diferentes procesos inflamatorios, en cuanto a la producción de mediadores solubles e interacción con el endotelio. Los monocitos no clásicos parecen ser los principales productores de mediadores inflamatorios como el TNF-α y la IL-1β en respuesta a la infección por DENV. Por lo tanto, se propone que cada subpoblación de monocitos debe tener un papel diferencial en la inmunopatología de la enfermedad.En esta revisión se recopilan los principales aspectos de la replicación viral y la inmunopatología del dengue, así como los principales hallazgos referentes al papel de los monocitos en esta infección y además, se propone un papel potencial y diferencial de las subpoblaciones de monocitos.

Infectivity of Zika virus on primary cells support tree shrew as animal model

Zika virus (ZIKV) is a mosquito-borne flavivirus that caused the public health emergency. Recently, we have proved a novel small animal tree shrew was susceptive to ZIKV infection and presented the most common rash symptoms as ZIKV patients. Here we further cultured the primary cells from different tissues of this animal to determine the tissue tropism of ZIKV infection in vitro. The results showed that the primary cells from tree shrew kidney, lung, liver, skin and aorta were permissive to ZIKV infection and could support viral replication by the detection of viral specific RNA intra- and extra-cells. In comparing, the skin fibroblast and vascular endothelial cells were highly permissive to ZIKV infection with high releasing of active virus particles in supernatants proved by its infectivity in established neonatal mouse model. The expressions of ZIKV envelop and nonstructural protein-1, and the effects and strong immune response of primary tree shrew cells were also detected followed by ZIKV infection. These findings provide powerful in vitro cell-level evidence to support tree shrew as animal model of ZIKV infection and may help to explain the rash manifestations in vivo.

Identification and Characterization at the Single-Cell Level of Cytokine-Producing Circulating Cells in Children With Dengue

In this study, we identified, at the single-cell level, naturally induced cytokine-producing circulating cells (CPCCs) in children with dengue virus (DENV) infection ranging clinically from mild to severe disease. Tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) CPCCs were detected in children with primary or secondary acute dengue virus (DENV) infection, and the pattern of these cytokines was similar to that seen in the supernatant of cultured peripheral blood mononuclear cells and partially comparable to that found in plasma. Monocytes, B cells, and myeloid dendritic cells (mDCs) were the primary CPCCs detected, and the frequency of mDCs was significantly higher in severe disease. B cells isolated from children with dengue spontaneously secreted TNF-α, IL-6, and interleukin 10, and supernatants from cultures of purified B cells induced activation of allogeneic T cells, supporting an antibody-independent function of these cells during DENV infection. Thus, CPCCs could be a new immune parameter with potential use to evaluate pathogenesis in this infection.

Transcriptome Profiling Reveals Pro-Inflammatory Cytokines and Matrix Metalloproteinase Activation in Zika Virus Infected Human Umbilical Vein Endothelial Cells

The deformities in the newborns infected with Zika virus (ZIKV) present a new potential public health threat to the worldwide community. Although ZIKV infection is mainly asymptomatic in healthy adults, infection during pregnancy can cause microcephaly and other severe brain defects and potentially death of the fetus. The detailed mechanism of ZIKV-associated damage is still largely unknown; however, it is apparent that the virus crosses the placental barrier to reach the fetus. Endothelial cells are the key structural component of the placental barrier. Endothelium integrity as semi-permeable barrier is essential to control the molecules and leukocytes trafficking across the placenta. Damaged endothelium or disruption of adherens junctions could compromise endothelial barrier integrity causing leakage and inflammation. Endothelial cells are often targeted by viruses, including the members of the Flaviviridae family such as dengue virus (DENV) and West Nile virus (WNV); however, little is known about the effects of ZIKV infection of endothelial cell functions. Our transcriptomic data have demonstrated that the large number of cytokines is affected in ZIKV-infected endothelial cells, where significant changes in 13 and 11 cytokines were identified in cells infected with PRVABC59 and IBH30656 ZIKV strains, respectively. Importantly, these cytokines include chemokines attracting mononuclear leukocytes (monocytes and lymphocytes) as well as neutrophils. Additionally, changes in matrix metalloproteinase (MMPs) were detected in ZIKV-infected cells. Furthermore, we for the first time showed that ZIKV infection of human umbilical vein endothelial cells (HUVECs) increases endothelial permeability. We reason that increased endothelial permeability was due to apoptosis of endothelial cells caused by caspase-8 activation in ZIKV-infected cells.

Preliminary study on the expression of endothelial cell biology related genes in the liver of dengue virus infected mice treated with Carica papaya leaf juice

Objective

The purpose of this study was to profile and identify the endothelial cell biology related genes that are affected by dengue virus infection in the liver tissue of AG129 mice, with and without Carica papaya leaf juice treatment.

Results

The dengue fever mouse model was established by intraperitoneal inoculation of dengue virus, New Guinea C strain at 2 × 10⁶ PFU. Daily oral administration of 1000 mg/kg freeze-dried C. papaya leaf juice (FCPLJ) was done starting from day 1 to day 3 post infection. The RNA was extracted from liver tissues harvested on day 4 post infection. The expression levels of 84 genes related to mouse endothelial cell biology were determined by qRT-PCR technique. Dengue virus infection upregulated 15 genes and downregulated two genes in the liver of AG129 mice. The FCPLJ treatment upregulated monocyte chemoattractant protein 1 and downregulated intercellular adhesion molecule 1, integrin beta 3 and fibronectin 1 genes during dengue virus infection. The data showed the potential effect of FCPLJ treatment on the expression profile of endothelial cell biology related genes in the liver of dengue virus infected-AG129 mice. Further proteomic studies are needed to determine the functional roles of the genes affected by FCPLJ treatment.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4242-z) contains supplementary material, which is available to authorized users.

Nonalcoholic fatty liver disease is associated with increased hemoconcentration, thrombocytopenia, and longer hospital stay in dengue-infected patients with plasma leakage

A prominent histopathological feature of fatal dengue cases is hepatic steatosis. However, the association between hepatic steatosis and dengue severity is unknown. We conducted a study to determine the associations of nonalcoholic fatty liver disease (NAFLD) with laboratory markers of dengue severity and length of hospital stay (LOS). A retrospective study was conducted at a private hospital in Jakarta, Indonesia, from December 2011 to December 2016. Bivariate analysis was performed to analyze the associations of laboratory markers of dengue severity and LOS with the presence or absence of NAFLD in no-plasma-leakage (no leakage) and plasma-leakage (leakage) groups. There were 267 dengue-infected patients included in this study. Of these patients, 115 (43.1%) were classified as belonging to the no leakage group, and 152 (56.9%) were classified as belonging to the leakage group. Of the 115 patients belonging to the no leakage group, 53 (46.1%) did not have NAFLD, and 62 (53.9%) had NAFLD. Of the 152 patients belonging to the leakage group, 85 (55.9%) did not have NAFLD, and 67 (44.1%) had NAFLD. Leakage group patients with NAFLD experienced significantly higher hemoconcentration severity (p = 0.04), lower platelet count (p = 0.004) and higher LOS (p = 0.042) than did leakage group patients without NAFLD. The presence of NAFLD in dengue-infected patients with plasma leakage was associated with more severe hemoconcentration, thrombocytopenia and prolonged hospital stay.

Upregulation of HLA-E by dengue and not Zika viruses

Introduction

The most severe form of dengue virus (DENV) illness, dengue haemorrhagic fever, is characterised by plasma leakage and increased vascular permeability.

Objectives

Given the critical role that endothelial cells play in the pathogenesis of DENV, we wanted to determine whether infection with DENV altered the expression of MHC class I related genes including HLA‐E.

Results

In this study, we provide evidence that HLA‐E but not MICA/B or HLA‐G is upregulated by all four serotypes of DENV in an endothelial cell line human microvascular endothelial cells (HMEC)‐1. In contrast, Zika virus (ZIKV), a related flavivirus, where plasma leakage is not a major manifestation of disease, did not upregulate HLA‐E. We found modest levels of soluble HLA‐E in supernatants from DENV but not ZIKV‐infected cells. Coculture experiments found minimal activation of natural killer (NK) cells in the presence of both uninfected and infected HMEC‐1 cells. HLA‐E induced by DENV infection could not dampen the degranulation of activated NK cells by interacting with its ligand NKG2a.

Conclusions

Our results suggest that while DENV infection induces HLA‐E, the high MHC class I expression on uninfected and infected HMEC‐1 cells may dominate the diverse signals generated between inhibitory and activating receptors on NK cells and ligands on target cells.

Which Dengue Vaccine Approach Is the Most Promising, and Should We Be Concerned about Enhanced Disease after Vaccination? Questions Raised by the Development and Implementation of Dengue Vaccines: Example of the Sanofi Pasteur Tetravalent Dengue Vaccine

Dengue is a still-growing public health concern in many tropical and subtropical regions of the world. The development and implementation of an effective dengue vaccine in these regions is a high priority. This insight focuses on the expected characteristics of a safe and efficacious vaccine, referring to the clinical experience obtained during the development of the first tetravalent dengue vaccine from Sanofi Pasteur, now licensed in several endemic countries. Safety and efficacy data from both short- and long-term follow-up of large-scale efficacy studies will be discussed, as well as the next steps following vaccine introduction.

Antiviral effect of compounds derived from the seeds of Mammea americana and Tabernaemontana cymosa on Dengue and Chikungunya virus infections

Background

The transmission of Dengue virus (DENV) and Chikungunya virus (CHIKV) has increased worldwide, due in part to the lack of a specific antiviral treatment. For this reason, the search for compounds with antiviral potential, either as licensed drugs or in natural products, is a research priority. The objective of this study was to identify some of the compounds that are present in Mammea americana (M. americana) and Tabernaemontana cymosa (T. cymosa) plants and, subsequently, to evaluate their cytotoxicity in VERO cells and their potential antiviral effects on DENV and CHIKV infections in those same cells.

Methods

Dry ethanolic extracts of M. americana and T. cymosa seeds were subjected to open column chromatographic fractionation, leading to the identification of four compounds: two coumarins, derived from M. americana; and lupeol acetate and voacangine derived from T. cymosa.. The cytotoxicity of each compound was subsequently assessed by the MTT method (at concentrations from 400 to 6.25 μg/mL). Pre- and post-treatment antiviral assays were performed at non-toxic concentrations; the resulting DENV inhibition was evaluated by Real-Time PCR, and the CHIKV inhibition was tested by the plating method. The results were analyzed by means of statistical analysis.

Results

The compounds showed low toxicity at concentrations ≤ 200 μg/mL. The compounds coumarin A and coumarin B, which are derived from the M. americana plant, significantly inhibited infection with both viruses during the implementation of the two experimental strategies employed here (post-treatment with inhibition percentages greater than 50%, p < 0.01; and pre-treatment with percentages of inhibition greater than 40%, p < 0.01). However, the lupeol acetate and voacangine compounds, which were derived from the T. cymosa plant, only significantly inhibited the DENV infection during the post-treatment strategy (at inhibition percentages greater than 70%, p < 0.01).

Conclusion

In vitro, the coumarins are capable of inhibiting infection by DENV and CHIKV (with inhibition percentages above 50% in different experimental strategies), which could indicate that these two compounds are potential antivirals for treating Dengue and Chikungunya fever. Additionally, lupeol acetate and voacangine efficiently inhibit infection with DENV, also turning them into promising antivirals for Dengue fever.

Impact of dengue virus (serotype DENV-2) infection on liver of BALB/c mice: A histopathological analysis

In this research, we characterized the histopathological impact of dengue virus (serotype DENV-2) infection in livers of BALB/c mice. The mice were infected with different doses of DENV-2 via intraperitoneal injection and liver tissues were processed for histological analyses and variation was documented. In the BALB/c mouse model, typical liver tissues showed regular hepatocyte architecture, with normal endothelial cells surrounding sinusoid capillary. Based on histopathological observations, the liver sections of BALB/c mice infected by DENV-2 exhibited a loss of cell integrity, with a widening of the sinusoidal spaces. There were marked increases in the infiltration of mononuclear cells. The areas of hemorrhage and micro- and macrovesicular steatosis were noted. Necrosis and apoptosis were abundantly present. The hallmark of viral infection, i.e., cytopathic effects, included intracellular edema and vacuole formation, cumulatively led to sinusoidal and lobular collapse in the liver. The histopathological studies on autopsy specimens of fatal human DENV cases are important to shed light on tissue damage for preventive and treatment modalities, in order to manage future DENV infections. In this framework, the method present here on BALB/c mouse model may be used to study not only the effects of infections by other DENV serotypes, but also to investigate the effects of novel drugs, such as recently developed nano-formulations, and the relative recovery ability with intact immune functions of host.

Primary dengue virus infections induce differential cytokine production in Mexican patients

Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient’s clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcription-polymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.

Poly(I:C) Induces Human Lung Endothelial Barrier Dysfunction by Disrupting Tight Junction Expression of Claudin-5

Viral infections are often accompanied by pulmonary microvascular leakage and vascular endothelial dysfunction via mechanisms that are not completely defined. Here, we investigated the effect of the Toll-like receptor 3 (TLR3) ligand polyinosinic-polycytidylic acid [Poly(I:C)], a synthetic analog of viral double-stranded RNA (dsRNA) commonly used to simulate viral infections, on the barrier function and tight junction integrity of primary human lung microvascular endothelial cells. Poly(I:C) stimulated IL-6, IL-8, TNFα, and IFNβ production in conjunction with the activation of NF-κB and IRF3 confirming the Poly(I:C)-responsiveness of these cells. Poly(I:C) increased endothelial monolayer permeability with a corresponding dose- and time-dependent decrease in the expression of claudin-5, a transmembrane tight junction protein and reduction of CLDN5 mRNA levels. Immunofluorescence experiments revealed disappearance of membrane-associated claudin-5 and co-localization of cytoplasmic claudin-5 with lysosomal-associated membrane protein 1. Chloroquine and Bay11-7082, inhibitors of TLR3 and NF-κB signaling, respectively, protected against the loss of claudin-5. Together, these findings provide new insight on how dsRNA-activated signaling pathways may disrupt vascular endothelial function and contribute to vascular leakage pathologies.

Transcriptome profiling reveals differential expression of interferon family induced by dengue virus 2 in human endothelial cells on tissue culture plastic and polyacrylamide hydrogel

A cell model is critical for studying the molecular mechanisms of dengue virus 2 (DENV-2) invasions and cell bioactivity can be easily affected by the substrate matrix. Tissue culture plastic (TCP) and polyacrylamide hydrogel (PAMH) are two kinds of matrices widely used for cells. The effects of different matrices on the cultured cells with DENV-2 invasion remain unknown. To address the issue, the effects of TCP and PAMH were explored in primary human umbilical vein endothelial cells (HUVECs) with DENV-2 invasion. HUVECs were assigned into four groups: group A (cultured on TCP), group B (cultured on PAMH), group C (cultured on TCP with DENV-2 invasion), and group D (cultured on PAMH with DENV-2 invasion). Flow cytometry was performed on HUVECs after 48-hr culture. Gene expression patterns were analyzed by gene microarray. The levels of interleukin-29 (IL-29) were measured by real-time qRT-PCR and ELISA. There were no cell apoptosis induced by DENV-2 in HUVECs cultured on TCP and PAMH (P > 0.05). After DENV-2 invasion, the up-regulated genes involve in the activities of oligoadenylate synthetase (OAS), interferon-related cytokine, and growth factors so on. The up-regulated pathways involve in the responses to DENV-2 and innate immunity. IL-29 was induced in the HUVECs on PAMH when compared with the cells on TCP (P < 0.05). Thus, different matrices cause different immune responses, which should be considered in the cell models for exploring the molecular mechanisms of DENV-induced diseases.

Regulators of endothelial integrity as severity predictors in dengue

INTRODUCTION

Dengue is currently among the mosquito-borne diseases of greatest global impact. The clinical course of the disease can be unpredictable, so proper handling in its early stages is critical to ensure optimal outcomes. 

OBJECTIVE

To evaluate serum regulators of endothelial integrity (VEGF, sICAM-1, sEndoglina, Ang-1, and Ang-2) as predictive markers of dengue severity. 

MATERIALS AND METHODS

We conducted a case-control study nested in an appropriate cohort. Endothelial regulator levels were first measured by ELISA, after which analysis was performed using logistic regression of clinical and regulatory variables, with severity as an output variable. A possible severity prediction model, based on the variables of interest and output, was defined using the best area under the ROC curve. 

RESULTS

The median subject age was 24 years. Severe cases were associated with Ang-2 serum levels of ≥1,490 ng/ml (OR=3.1; p=0.015). Serum levels of Ang-2 (≥1,490 ng/ml) contributed to the severity prediction model, as did a 0.73 area under the ROC curve, together with the variables rash, impaired consciousness and abdominal pain, with an OR of 3.2 (CI 95%: 1.16 to 8.9; p=0.024). 

CONCLUSION

The endothelial regulator Ang-2 could be a predictor of severity in dengue.

Anti-dengue virus nonstructural protein 1 antibodies contribute to platelet phagocytosis by macrophages

Thrombocytopenia is an important clinical manifestation of dengue disease. The hypotheses concerning the pathogenesis of thrombocytopenia include decreased production and increased destruction or consumption of platelets. We previously suggested a mechanism of molecular mimicry in which antibodies (Abs) directed against dengue virus (DENV) nonstructural protein 1 (NS1) cross-react with platelets. Furthermore, several lines of evidence show activation of endothelial cells (ECs) and macrophages are related to dengue disease severity. Previous studies also suggested that Ab-opsonised platelets facilitate the engulfment of platelets by macrophages. Here we show that TNF-α-activated ECs upregulate adhesion molecule expression to enhance the binding of platelets and macrophages and lead to anti-DENV NS1 Ab-mediated platelet phagocytosis. We further demonstrate that the interaction between macrophages and TNF-α-activated ECs requires binding of FcγR with the Fc region of platelet-bound anti-DENV NS1 Abs. Importantly, the binding of anti-DENV NS1 Abs to platelets did not interfere with platelet adhesion to ECs. The adhesion molecules ICAM-1 and β3 integrin expressed on ECs as well as the FcγR expressed on macrophages were critical in anti-DENV NS1 Ab-mediated platelet phagocytosis on activated ECs. Moreover, anti-DENV NS1 Abs dramatically enhanced platelet engulfment by macrophages in a murine model of DENV infection. Our study provides evidence for a novel role for anti-DENV NS1 Abs in the pathogenesis of thrombocytopenia in dengue disease by enhancing platelet phagocytosis by macrophages.