Levels of soluble ST2 in serum associated with severity of dengue due to tumour necrosis factor alpha stimulation

Small extracellular vesicles from the human endothelial cell line EA.hy 926 exert a self-cell activation and modulate DENV-2 genome replication and infection in naïve endothelial cells

Extracellular vesicles (EVs) play crucial roles in cell signaling and communication, transporting molecules that convey a message to target cells. During infectious diseases, EVs can also carry viral molecules that may contribute to viral spread, as previously reported for dengue virus (DENV). EVs from infected endothelial cells (EC) may harbor viral segments and various sets of molecules that could contribute to endothelial dysfunction during severe dengue. However, the effect of these EVs on non-infected EC (NIC) remain unknown. We characterized the EVs produced by the human EC line EA.hy 926 infected with DENV-2 and assessed their functional impact on polarized NIC. Results showed that infection induced an increased in the quantity of produced EVs, which differentially carried proteins mainly involved in proteosome activity, along with a peptide of the NS5 viral protein. Additionally, all types of Y-RNAs were found, accompanied by a set of differentially loaded microRNAs (miRs) that could regulate DENV genome. Pre-treatment of polarized NIC with small EVs (sEVs) from infected EC before DENV-2 infection caused EC activation, a decrease in viral genome replication, and a protective effect against barrier disruption during the first 24h post-infection, suggesting that sEVs could be important in the pathology or resolution of DENV and a promising therapeutic tool for infectious diseases.

Kinetics of cardiovascular and inflammatory biomarkers in paediatric dengue shock syndrome

Glycocalyx disruption and hyperinflammatory responses are implicated in the pathogenesis of dengue-associated vascular leak, however little is known about their association with clinical outcomes of patients with dengue shock syndrome (DSS). We investigated the association of vascular and inflammatory biomarkers with clinical outcomes and their correlations with clinical markers of vascular leakage. We performed a prospective cohort study in Viet Nam. Children ≥5 years of age with a clinical diagnosis of DSS were enrolled into this study. Blood samples were taken daily during ICU stay and 7-10 days after hospital discharge for measurements of plasma levels of Syndecan-1, Hyaluronan, Suppression of tumourigenicity 2 (ST-2), Ferritin, N-terminal pro Brain Natriuretic Peptide (NT-proBNP), and Atrial Natriuretic Peptide (ANP). The primary outcome was recurrent shock. Ninety DSS patients were enrolled. Recurrent shock occurred in 16 patients. All biomarkers, except NT-proBNP, were elevated at presentation with shock. There were no differences between compensated and decompensated DSS patients. Glycocalyx markers were positively correlated with inflammatory biomarkers, haematocrit, percentage haemoconcentration, and negatively correlated with stroke volume index. While Syndecan-1, Hyaluronan, Ferritin, and ST-2 improved with time, ANP continued to be raised at follow-up. Enrolment Syndecan-1 levels were observed to be associated with developing recurrent shock although the association did not reach the statistical significance at the P < 0.01 (OR = 1.82, 95% CI 1.07-3.35, P = 0.038). Cardiovascular and inflammatory biomarkers are elevated in DSS, correlate with clinical vascular leakage parameters and follow different kinetics over time. Syndecan-1 may have potential utility in risk stratifying DSS patients in ICU.

Soluble suppression of tumorigenicity-2 in pregnancy with a small-for-gestational-age fetus and with preeclampsia

OBJECTIVE

Preeclampsia and fetal growth disorders are pregnancy-specific conditions that share common pathophysiological mechanisms. Yet, why some patients develop preeclampsia while others experience fetal growth restriction, or a combination of both clinical presentations, is unknown. We propose that the difference in severity of the maternal inflammatory response can contribute to the clinical phenotypes of preeclampsia vs. small for gestational age (SGA). To assess this hypothesis, we measured maternal plasma concentrations of the soluble isoform of suppression of tumorigenicity-2 (sST2), a member of the interleukin-1 receptor family that buffers proinflammatory responses. Previous reports showed that serum sST2 concentrations rise in the presence of intravascular inflammation and Th1-type immune responses and are significantly higher in patients with preeclampsia compared to those with normal pregnancy. The behavior of sST2 in pregnancies complicated by SGA has not been reported. This study was conducted to compare sST2 plasma concentrations in normal pregnancies, in those with preeclampsia, and in those with an SGA fetus.

METHODS

This retrospective cross-sectional study included women with an SGA fetus (n = 52), women with preeclampsia (n = 106), and those with normal pregnancy (n = 131). Maternal plasma concentrations of sST2 were determined by enzyme-linked immunosorbent assay. Doppler velocimetry of the uterine and umbilical arteries was available in a subset of patients with SGA (42 patients and 43 patients, respectively).

RESULTS

(1) Women with an SGA fetus had a significantly higher median plasma concentration of sST2 than normal pregnant women (p = .008); (2) women with preeclampsia had a significantly higher median plasma concentration of sST2 than those with normal pregnancy (p < .001) and those with an SGA fetus (p < .001); (3) patients with SGA and abnormal uterine artery Doppler velocimetry had a higher median plasma concentration of sST2 than controls (p < .01) and those with SGA and normal uterine artery Doppler velocimetry (p = .02); (4) there was no significant difference in the median plasma sST2 concentration between patients with SGA who had normal uterine artery Doppler velocimetry and controls (p = .4); (5) among patients with SGA, those with abnormal and those with normal umbilical artery Doppler velocimetry had higher median plasma sST2 concentrations than controls (p = .001 and p = .02, respectively); and (6) there was no significant difference in the median plasma sST2 concentrations between patients with SGA who did and those who did not have abnormal umbilical artery Doppler velocimetry (p = .06).

CONCLUSIONS

Preeclampsia and disorders of fetal growth are conditions characterized by intravascular inflammation, as reflected by maternal plasma concentrations of sST2. The severity of intravascular inflammation is highest in patients with preeclampsia.

Early biomarkers for prediction of severe manifestations of dengue fever: a systematic review and a meta-analysis

Early identification of dengue patients at risk of adverse outcomes is important to prevent hospital overcrowding in low- to middle- income countries during epidemics. We performed a systematic review to identify which biomarkers measured in first 96 h of fever could predict dengue haemorrhagic fever (DHF, World Health Organization 1997 clinical classification) or severe dengue (SD, WHO 2009, clinical classification). PubMed, Scopus, CINAHL, Web of Science, and EMBASE databases were searched for prospective cohort and nested case-control studies published from 1997 to Feb 27, 2022. The protocol for the study was registered in PROSPERO (ID: CRD42021230053). After screening 6747 publications, and analysing 37 eligible studies reporting on 5925 patients, elevated C-reactive protein, aspartate aminotransferase, interleukin-8 and decreased albumin levels were strongly associated with dengue haemorrhagic fever (by meta-analyses of multiple studies, p < 0.05), while elevated vascular cell adhesion protein 1, syndecan-1, aspartate aminotransferase and C-reactive protein levels were strongly associated with severe dengue (by meta-analyses of multiple studies, p < 0.05). Further 44 and 28 biomarkers were associated with the risk of DHF and SD respectively, but only in a single study. The meta-analyses suggest the importance of early acute inflammation with hepatic involvement in determining the subsequent course of illness in dengue.

Unique Immune Blood Markers Between Severe Dengue and Sepsis in Children

BACKGROUND

Pediatric dengue and sepsis share clinical and pathophysiologic aspects. Multiple inflammatory and regulatory cytokines, decoy receptors and vascular permeability factors have been implicated in the pathogenesis of both diseases. The differential pattern and dynamic of these soluble factors, and the relationship with clinical severity between pediatric dengue and sepsis could offer new diagnosis and therapeutic strategies.

METHODS

We evaluated the concentration levels of 11 soluble factors with proinflammatory, regulatory and vascular permeability involvement, in plasma from children with dengue or sepsis, both clinically ranging from mild to severe, in the early, late and convalescence phases of the disease.

RESULTS

During early acute infection, children with sepsis exhibited specific higher concentration levels of IL-6, vascular endothelial growth factor (VEGF), and its soluble decoy receptor II (sVEGFR2) and lower concentration levels of IL-10 and the soluble tumor necrosis factor receptor 2 (sTNFR2), in comparison with children with severe dengue. In addition, the circulating amounts of soluble ST2, and VEGF/sVEGFR2 were widely associated with clinical and laboratory indicators of dengue severity, whereas secondary dengue virus infections were characterized by an enhanced cytokine response, relative to primary infections. In severe forms of dengue, or sepsis, the kinetics and the cytokines response during the late and convalescence phases of the disease also differentiate.

CONCLUSIONS

Dengue virus infection and septic processes in children are characterized by cytokine responses of a specific magnitude, pattern and kinetics, which are implicated in the pathophysiology and clinical outcome of these diseases.

Clinical and prognostic relevance of sST2 in adults with dengue-associated cardiac impairment and severe dengue

BACKGROUND

Dengue can be complicated by severe outcomes including cardiac impairment, and the lack of reliable prognostic biomarkers poses a challenge in managing febrile dengue patients. Here, we investigated the functionality of soluble suppressor of tumorigenicity (sST2) as a predictive marker of severe dengue and its association in dengue-associated cardiac impairment.

METHODS

Plasma samples, aged >16 years, collected from 36 dengue fever, 43 dengue with warning signs, 11 severe dengue (collected at febrile, critical and recovery phases) and 30 controls were assayed for plasma levels of sST2, troponin T and N-terminal (NT)-pro hormone brain natriuretic peptide (NT-proBNP) by ELISA. Cardiac parameters: stroke index (SI), cardiac index (CI) and Granov-Goor Index (GGI) were measured with a bioimpedance device during the different phases for dengue subjects and once for the controls.

PRINCIPAL FINDINGS

In the febrile, critical and early recovery phases, sST2 levels were significantly elevated in dengue participants and sST2 levels increased with increasing disease severity (P < 0.01 for all). sST2 concentrations were negatively correlated with SI (r = -0.48; P < 0.001, r = -0.55; P < 0.001), CI (r = -0.26; P = 0.02, r = -0.6: P < 0.001) and GGI (r = -0.44; P < 0.001, r = -0.57; P < 0.001) in the critical and early recovery phases. In contrast, sST2 levels in the febrile and critical phases, were positive correlated to troponin T (r = 0.44, P < 0.001; r = 0.22, P = 0.03, respectively) and NT-proBNP (r = 0.21, P = 0.03; r = 0.35, P < 0.001). ROC analysis demonstrated sST2 as a good biomarker of severe dengue in the critical phase, AUROC 0.79, P < 0.001.

CONCLUSION/SIGNIFICANCE

sST2 levels were elevated in patients with dengue especially in cases of severe dengue. Furthermore, increased sST2 levels were associated with cardiac indicators suggesting lower cardiac performance. While further research is needed to demonstrate its clinical utility, sST2 may be a useful prognostic biomarker of severe dengue.

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.

Role of cytokines produced by T helper immune-modulators in dengue pathogenesis: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Modulation of the immune reaction is essential in the development of various diseases, including dengue's "Cytokine Tsunami", an increase in vascular permeability with concomitant severe vascular leakage. We aim to identify the role of T-helper (Th) cells, Th2 and Th7, with their related cytokines in dengue pathogenesis.

MATERIAL AND METHODS

Nine electronic databases and manual search were applied to detect available publications. A meta-analysis using a fixed- or random-effect model was performed to measure standardized mean difference (SMD) with 95% confidence interval (CI). The National Institute of Health (NIH) tools for observational cohort, cross-sectional, and case-control studies were used to examine the risk of bias. The protocol was recorded in PROSPERO with CRD42017060230.

RESULTS

A total of 38 articles were found including 19 case-control, 11 cross-sectional and 8 prospective cohort studies. We indicated that Th2 cytokines (IL-4, IL-6, IL-8) and Th17 cytokine (IL-17) in dengue patients were notably higher than in a healthy control group in acute phase (SMD = 1.59, 95% CI [0.68, 2.51], p = 0.001; SMD = 1.24, 95% CI [0.41, 2.06], p = 0.003; SMD = 1.13, 95% CI [0.61, 1.66], p<0.0001; SMD = 1.74, 95% CI [0.87, 2.61], p<0.0001), respectively.

CONCLUSIONS

This study provides evidence of the significant roles of IL-4, IL-6, IL-8, IL-10 and IL-17 in the pathogenesis of developing a severe reaction in dengue fever. However, to fully determine the association of Th cytokines with dengue, it is necessary to perform further studies to assess kinetic levels during the duration of the illness.

Multivariate time-series analysis of biomarkers from a dengue cohort offers new approaches for diagnosis and prognosis

Dengue is a major public health problem worldwide with distinct clinical manifestations: an acute presentation (dengue fever, DF) similar to other febrile illnesses (OFI) and a more severe, life-threatening form (severe dengue, SD). Due to nonspecific clinical presentation during the early phase of dengue infection, differentiating DF from OFI has remained a challenge, and current methods to determine severity of dengue remain poor early predictors. We present a prospective clinical cohort study conducted in Caracas, Venezuela from 2001-2005, designed to determine whether clinical and hematological parameters could distinguish DF from OFI, and identify early prognostic biomarkers of SD. From 204 enrolled suspected dengue patients, there were 111 confirmed dengue cases. Piecewise mixed effects regression and nonparametric statistics were used to analyze longitudinal records. Decreased serum albumin and fibrinogen along with increased D-dimer, thrombin-antithrombin complex, activated partial thromboplastin time and thrombin time were prognostic of SD on the day of defervescence. In the febrile phase, the day-to-day rates of change in serum albumin and fibrinogen concentration, along with platelet counts, were significantly decreased in dengue patients compared to OFI, while the day-to-day rates of change of lymphocytes (%) and thrombin time were increased. In dengue patients, the absolute lymphocytes to neutrophils ratio showed specific temporal increase, enabling classification of dengue patients entering the critical phase with an area under the ROC curve of 0.79. Secondary dengue patients had elongation of Thrombin time compared to primary cases while the D-dimer formation (fibrinolysis marker) remained always lower for secondary compared to primary cases. Based on partial analysis of 31 viral complete genomes, a high frequency of C-to-T transitions located at the third codon position was observed, suggesting deamination events with five major hot spots of amino acid polymorphic sites outside in non-structural proteins. No association of severe outcome was statistically significant for any of the five major polymorphic sites found. This study offers an improved understanding of dengue hemostasis and a novel way of approaching dengue diagnosis and disease prognosis using piecewise mixed effect regression modeling. It also suggests that a better discrimination of the day of disease can improve the diagnostic and prognostic classification power of clinical variables using ROC curve analysis. The piecewise mixed effect regression model corroborated key early clinical determinants of disease, and offers a time-series approach for future vaccine and pathogenesis clinical studies.

Dynamic changes of soluble ST2 levels predicted fatality and were involved in coagulopathy in dengue fever in the elderly

Background

Severe dengue virus (DENV) infection involves plasma leakage and vascular collapse, and leads to significant morbidity and death. Serum soluble ST2 (sST2 [interleukin (IL)-1 receptor like-1 protein: IL-1-RL-1]) levels are high in pediatric cases of DENV infection, and the disease progresses. However, the correlation between serum sST2 levels and the outcomes of DENV infection in the elderly (≥65 years) is unclear. We thus explored the mechanisms of serial sST2 level changes involved in the coagulopathy and bloodstream infections of elderly patients in Taiwan’s 2015 DENV outbreak.

Methods

This retrospective study was done in a tertiary medical center in southern Taiwan during the outbreak. All DENV-infected patients who, between July 1, 2015, and December 31, 2015, provided a written informed consent for at least two blood sample analyses were enrolled and reviewed. The serum levels of sST2 were quantified. ΔsST2 is defined as the “changes of sST2 levels in serially paired samples”. Receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) analyses were used to evaluate the prognostic ability of ΔsST2.

Results

Forty-three patients with DENV infection were enrolled. Mean patient age was 75.0 ± 12.2 years and the case fatality rate was 44.2% (19/43). Significantly more non-survivors than survivors had increased ST2 level (78.9% vs. 12.5%, p < 0.001). The AUC value for serum ΔsST2 level was 0.857 for predicting DENV fatality. Moreover, patients given frozen fresh plasma (FFP) transfusions were significantly (p = 0.025) more likely to have higher serum ST2 level changes than were those who had not. DENV-infected patients with early bloodstream infections (BSIs) seemed to have higher ST2 levels than those who did not have BSIs.

Conclusions

Serum ST2 levels increased in the elderly (≥ 65 years of age) with DENV infection. The changes in serum sST2 levels might be a critical indicator of DENV infection severity for the elderly; sST2 is an important modulator of coagulopathy in severe DENV infections.

Dengue virus (DENV) infection is a mosquito-borne disease that annually affects at least 50 million people worldwide. The cytokine response during DENV infection is mercurial and abstruse. IL-1 receptor-like-1 (IL-1R-L-1 [aka ST2]) protein is associated with the severity of DENV infection, and elevated cytokine levels are important early predictors of dengue hemorrhagic fever and dengue shock syndrome. ST2, a member of the interleukin-1-receptor/toll-like receptor (TLR) superfamily, is an important biomarker of severe forms of pediatric DENV infection. We first confirmed a similar trend in the elderly cohort. Serial changes of soluble ST2 (sST2) levels were a more reliable predictor for dengue fatality than a single measurement was. Patients given fresh frozen plasma (FFP) transfusions had significantly higher serum ST2 levels than those who had not been given FFP transfusions. SerumsST2 might be necessary for modulating coagulopathy in severe DENV infections. The exact molecular mechanism and the optimal timing for sST2 testing need further investigation.

Raman spectroscopy based differentiation of typhoid and dengue fever in infected human sera

This study investigated the potential of Raman spectroscopy, to differentiate between two different types of human pathological conditions with some symptom similarity; typhoid and dengue. Raman spectra were recorded from 20 Salmonella Typhi infected and 22 dengue virus (DENV) infected sera samples using laser wavelength 785 nm. When Raman spectrum (540 to 1830 cm^-1) of serum samples was compared it showed significant variations. Twelve characteristic Raman bands at 562, 649, 716, 780, 838, 1099, 1144, 1156, 1260, 1386, 1556 and 1746 cm^-1 were recorded specifically in case of the typhoid infected samples, whereas four Raman bands at 756, 1218, 1672 and 1686 cm^-1 were found specifically in the DENV infected samples. For statistical differentiation principal component analysis (PCA) and linear discriminant analysis (LDA) was applied which successfully separated two sets of data. These disease specific Raman signatures may be labeled as biomarkers for identification as well as differential diagnosis of typhoid and dengue infection. Hence we propose that Raman spectroscopy has the potential to not only identify but also to differentiate between different pathological conditions, having some similar symptoms like high grade fever in this case.

Interleukin-33 contributes to disease severity in Dengue virus infection in mice

The excessive inflammation often present in patients with severe dengue infection is considered both a hallmark of disease and a target for potential treatments. Interleukin-33 (IL-33) is a pleiotropic cytokine with pro-inflammatory effects whose role in dengue has not been fully elucidated. We demonstrate that IL-33 plays a disease-exacerbating role during experimental dengue infection in immunocompetent mice. Mice infected with dengue virus serotype 2 (DENV2) produced high levels of IL-33. DENV2-infected mice treated with recombinant IL-33 developed markedly more severe disease compared with untreated mice as assessed by mortality, granulocytosis, liver damage and pro-inflammatory cytokine production. Conversely, ST2^-/- mice (deficient in IL-33 receptor) infected with DENV2 developed significantly less severe disease compared with wild-type mice. Furthermore, the increased disease severity and the accompanying pathology induced by IL-33 during dengue infection were reversed by the simultaneous treatment with a CXCR2 receptor antagonist (DF2156A). Together, these results indicate that IL-33 plays a disease-exacerbating role in experimental dengue infection, probably driven by CXCR2-expressing cells, leading to elevated pro-inflammatory response-mediated pathology. Our results also indicate that IL-33 is a potential therapeutic target for dengue infection.

Profiling of Microrna Expression within the Cells of Peripheral Blood Mononuclear after an Infection with Serotype-2 of Dengue Virus: Preliminary Study

The role of microRiboNucleic Acids (miRNA), a small-non coding RNA has been associated with immune regulation in various viral infectionincluding dengue infection. The microRNA will bind a specific protein target in order to encourage an explosive expression of various cytokines, known as cytokines storm in Dengue infection.The objective of this study aimed to determine and evaluate themicroRNAs profile expression withinperipheral blood mononuclear cells having been infected with one of the dengue virus serotype.To obtained the PBMCs from a healthy donor, Ficoll density gradient centrifugation was used to isolate the PBMCs and then followed infecting it with a DENV-2 clinical isolate. Prior to PBMCs isolation, the virus has been propagated and having titration to get an optimal virus titer. We conducted the infection at the multiplication of infections 4 PFU/106 cells.MiRCURYLNATMExiqon was utilized on purpose to extract the RNA. Quantitative Real-Time PCR was applied in order for the miRNAs relative expression to be measured. The preliminary result reveals that miR-150, miR-146a, hsa-let-7e expression were increased 1.74 folds, 2 folds, and 1.49 foldsrespectively at 12 hours post-infection on PBMCs upon DENV-2 infection.The expression of microRNAswas discovered to behigher inPBMCsat the time of infection withDENV-2.ThemiRNAs expression in the uninfected PMBCs was lower than that of the miRNA. This high expression of miRNAsin dengue infection may proceedto dengue infection pathogenesis.

Meta-analysis of biomarkers for severe dengue infections

BACKGROUND

Dengue viral infection is an acute infection that has the potential to have severe complications as its major sequela. Currently, there is no routine laboratory biomarker with which to predict the severity of dengue infection or monitor the effectiveness of standard management. Hence, this meta-analysis compared biomarker levels between dengue fever (DF) and severe dengue infections (SDI) to identify potential biomarkers for SDI.

METHODS

Data concerning levels of cytokines, chemokines, and other potential biomarkers of DF, dengue hemorrhagic fever, dengue shock syndrome, and severe dengue were obtained for patients of all ages and populations using the Scopus, PubMed, and Ovid search engines. The keywords "(IL1* or IL-1*) AND (dengue*)" were used and the same process was repeated for other potential biomarkers, according to Medical Subject Headings terms suggested by PubMed and Ovid. Meta-analysis of the mean difference in plasma or serum level of biomarkers between DF and SDI patients was performed, separated by different periods of time (days) since fever onset. Subgroup analyses comparing biomarker levels of healthy plasma and sera controls, biomarker levels of primary and secondary infection samples were also performed, as well as analyses of different levels of severity and biomarker levels upon infection by different dengue serotypes.

RESULTS

Fifty-six studies of 53 biomarkers from 3,739 dengue cases (2,021 DF and 1,728 SDI) were included in this meta-analysis. Results showed that RANTES, IL-7, IL-8, IL-10, IL-18, TGF-b, and VEGFR2 levels were significantly different between DF and SDI. IL-8, IL-10, and IL-18 levels increased during SDI (95% CI, 18.1-253.2 pg/mL, 3-13 studies, n = 177-1,909, I2 = 98.86%-99.75%). In contrast, RANTES, IL-7, TGF-b, and VEGFR2 showed a decrease in levels during SDI (95% CI, -3238.7 to -3.2 pg/mL, 1-3 studies, n = 95-418, I2 = 97.59%-99.99%). Levels of these biomarkers were also found to correlate with the severity of the dengue infection, in comparison to healthy controls. Furthermore, the results showed that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 display peak differences between DF and SDI during or before the critical phase (day 4-5) of SDI.

DISCUSSION

This meta-analysis suggests that IL-7, IL-8, IL-10, TGF-b, and VEGFR2 may be used as potential early laboratory biomarkers in the diagnosis of SDI. This can be used to predict the severity of dengue infection and to monitor the effectiveness of treatment. Nevertheless, methodological and reporting limitations must be overcome in future research to minimize variables that affect the results and to confirm the findings.

Mathematical modelling and a systems science approach to describe the role of cytokines in the evolution of severe dengue

Background

Dengue causes considerable morbidity and mortality in Sri Lanka. Inflammatory mediators such as cytokines, contribute to its evolution from an asymptotic infection to severe forms of dengue. The majority of previous studies have analysed the association of individual cytokines with clinical disease severity. In contrast, we view evolution to Dengue Haemorrhagic Fever as the behaviour of a complex dynamic system. We therefore, analyse the combined effect of multiple cytokines that interact dynamically with each other in order to generate a mathematical model to predict occurrence of Dengue Haemorrhagic Fever. We expect this to have predictive value in detecting severe cases and improve outcomes. Platelet activating factor (PAF), Sphingosine 1- Phosphate (S1P), IL-1β, TNFα and IL-10 are used as the parameters for the model. Hierarchical clustering is used to detect factors that correlated with each other. Their interactions are mapped using Fuzzy Logic mechanisms with the combination of modified Hamacher and OWA operators. Trapezoidal membership functions are developed for each of the cytokine parameters and the degree of unfavourability to attain Dengue Haemorrhagic Fever is measured.

Results

The accuracy of this model in predicting severity level of dengue is 71.43% at 96 h from the onset of illness, 85.00% at 108 h and 76.92% at 120 h. A region of ambiguity is detected in the model for the value range 0.36 to 0.51. Sensitivity analysis indicates that this is a robust mathematical model.

Conclusions

The results show a robust mathematical model that explains the evolution from dengue to its serious forms in individual patients with high accuracy. However, this model would have to be further improved by including additional parameters and should be validated on other data sets.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-017-0415-3) contains supplementary material, which is available to authorized users.

Maternal plasma-soluble ST2 concentrations are elevated prior to the development of early and late onset preeclampsia - a longitudinal study

OBJECTIVE

The objectives of this study were to determine (1) the longitudinal profile of plasma soluble ST2 (sST2) concentrations in patients with preeclampsia and those with uncomplicated pregnancies; (2) whether the changes in sST2 occur prior to the diagnosis of preeclampsia; and (3) the longitudinal sST2 profile of women with early or late preeclampsia.

MATERIALS AND METHODS

This longitudinal nested case-control study included singleton pregnancies in the following groups: (1) uncomplicated pregnancies (n = 160); and (2) those complicated by early (<34 weeks, n = 9) and late (≥34 weeks, n = 31) preeclampsia. sST2 concentrations were determined by enzyme-linked immunosorbent assays. Mixed-effects models were used for the longitudinal analysis.

RESULTS

(1) Plasma sST2 concentration profiles across gestation differed significantly among cases and controls (p < 0.0001); (2) women with early preeclampsia had higher mean sST2 concentrations than controls at >22 weeks of gestation; cases with late preeclampsia had higher mean concentrations at >33 weeks of gestation (both p < 0.05); and (3) these changes started approximately 6 weeks prior to clinical diagnosis.

CONCLUSIONS

Maternal plasma sST2 concentrations are elevated 6 weeks prior to the clinical diagnosis of preeclampsia. An increase in the maternal plasma concentration of sST2 may contribute to an exaggerated intravascular inflammatory response and/or the Th1/Th2 imbalance in some cases.

Gene expression profiling to identify the toxicities and potentially relevant disease outcomes due to endosulfan exposure

Endosulfan, one of the most toxic organochlorine pesticides, belongs to a group of persistent organic pollutants. Gene expression profiling offers a promising approach in health hazard identification of chemicals. The aim of this study was to use gene expression profiling to identify the toxicities and potentially relevant human diseases due to endosulfan exposure. We performed DNA microarray analysis to analyze gene expression profiles in human endothelial cells exposed to 20, 40 and 60 μM endosulfan in combination with an endothelial phenotype. Microarray results showed that endosulfan increased the number of altered genes in a dose-dependent manner, and changed the expression of 161 genes across all treatment groups. qRT-PCR closely matched the microarray data for the genes tested. Significantly enriched biological processes for overlapping down-regulated genes include the neurological system process, signal transduction, and homeostatic process in all the dose groups. These down-regulated genes were associated with cytoskeleton organization and DNA repair at low doses, and involved in cell cycle, apoptosis, p53 pathway and carcinogenesis at high doses. Those up-regulated genes were linked to the inflammatory response and transcriptional misregulation in cancer at higher doses. These findings are consistent with our established endothelial phenotypes. Endosulfan may be relevant to human diseases including liver cancer, prostate cancer and leukemia using the NextBio Human Disease Atlas. These results provide molecular evidence supporting the toxicities and carcinogenic potential of endosulfan in humans.

Biomarkers of severe dengue disease - a review

Dengue virus infection presents a wide spectrum of manifestations including asymptomatic condition, dengue fever (DF), or severe forms, such as dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) in affected individuals. The early prediction of severe dengue in patients without any warning signs who may later develop severe DHF is very important to choose appropriate intensive supportive therapy since available vaccines for immunization are yet to be approved. Severe dengue responses include T and B cell activation and apoptosis, cytokine storm, hematologic disorders and complement activation. Cytokines, complement and other unidentified factors may transiently act on the endothelium and alter normal fluid barrier function of the endothelial cells and cause plasma leakage. In this review, the host factors such as activated immune and endothelial cells and their products which can be utilized as biomarkers for severe dengue disease are discussed.

Host biomarkers are associated with progression to dengue haemorrhagic fever: a nested case-control study

OBJECTIVES

Dengue represents the most important arboviral infection worldwide. Onset of circulatory collapse can be unpredictable. Biomarkers that can identify individuals at risk of plasma leakage may facilitate better triage and clinical management.

DESIGN

Using a nested case-control design, we randomly selected subjects from a prospective cohort study of dengue in Colombia (n=1582). Using serum collected within 96 hours of fever onset, we tested 19 biomarkers by ELISA in cases (developed dengue hemorrhagic fever or dengue shock syndrome (DHF/DSS); n=46), and controls (uncomplicated dengue fever (DF); n=65) and healthy controls (HC); n=15.

RESULTS

Ang-1 levels were lower and angptl3, sKDR, sEng, sICAM-1, CRP, CXCL10/IP-10, IL-18 binding protein, CHI3L1, C5a and Factor D levels were increased in dengue compared to HC. sICAM-1, sEng and CXCL10/IP-10 were further elevated in subjects who subsequently developed DHF/DSS (p=0.008, p=0.028 and p=0.025, respectively). In a logistic regression model, age (odds ratio (OR) (95% CI): 0.95 (0.92-0.98), p=0.001), hyperesthesia/hyperalgesia (OR; 3.8 (1.4-10.4), p=0.008) and elevated sICAM-1 (>298ng/mL: OR; 6.3 (1.5-25.7), p=0.011) at presentation were independently associated with progression to DHF/DSS.

CONCLUSIONS

These results suggest that inflammation and endothelial activation are important pathways in the pathogenesis of dengue and sICAM-1 levels may identify individuals at risk of plasma leakage.

Dengue fever in patients under biologics

Dengue fever (DF) is an epidemic viral mosquito-borne infection limited to tropical and subtropical countries. Biological therapies have been frequently used for the last 15 years in the treatment of inflammatory rheumatic conditions like rheumatoid arthritis. However, no data is available regarding the characteristics of this infection in patients on biological therapy. Yet, numerous patients on biotherapy have holidays in countries where DF exists. Moreover, the mosquitoes Aedes albopictus, vector of this viral disease, is now found in some developed countries such as southern Europe and the USA, allowing the possibility of a DF outbreak. We conducted a survey of individuals on biotherapy and described a case series of the patients experiencing DF. Our 8 patients on biotherapy (anti-TNF, n=6; rituximab, n=2) for a rheumatic condition did not experience severe DF.

Receptor-activated human α2-macroglobulin interacts with the envelope protein of dengue virus and protects virions from temperature-induced inactivation through multivalent binding

Based on the hypothesis that interactions between virions and serum components may influence the outcome of dengue virus (DENV) infections, we decided to use affinity chromatography with domain III from the envelope (E) protein of DENV2 (DIIIE2) as a ligand to isolate virus-binding proteins from human plasma. This approach yielded serum amyloid P (SAP) and α2-macroglobulin (α2M) as novel viral interactors. After confirming the specific binding of both SAP and α2M to DIIIE2 by ELISA, the latter interaction was examined in greater detail. We obtain evidence suggesting that the binding species was actually the receptor-activated form of α2M (α2M*), that α2M* could bind monovalently to recombinant domain III from all four DENV serotypes with affinities in the micromolar range ranking as DENV4>DENV1~DENV2>DENV3 and that this interaction exhibited a strong avidity effect when multivalent binding was favoured (KD 8 × 10(-8) M for DIIIE2). We also showed that α2M* bound to DENV virions of the four serotypes, protecting the virus from temperature-induced inactivation in the absence of serum and enhancing infectivity. The latter effect exhibited an ED50 of 2.9 × 10(-8) M, also suggesting an avidity effect due to multivalent binding. These results will further contribute to the characterization of the virus-host factor interaction network during human DENV infection.

Type I interferon signals in macrophages and dendritic cells control dengue virus infection: implications for a new mouse model to test dengue vaccines

Dengue virus (DENV) infects an estimated 400 million people every year, causing prolonged morbidity and sometimes mortality. Development of an effective vaccine has been hampered by the lack of appropriate small animal models; mice are naturally not susceptible to DENV and only become infected if highly immunocompromised. Mouse models lacking both type I and type II interferon (IFN) receptors (AG129 mice) or the type I IFN receptor (IFNAR(-/-) mice) are susceptible to infection with mouse-adapted DENV strains but are severely impaired in mounting functional immune responses to the virus and thus are of limited use for study. Here we used conditional deletion of the type I IFN receptor (IFNAR) on individual immune cell subtypes to generate a minimally manipulated mouse model that is susceptible to DENV while retaining global immune competence. Mice lacking IFNAR expression on CD11c(+) dendritic cells and LysM(+) macrophages succumbed completely to DENV infection, while mice deficient in the receptor on either CD11c(+) or LysM(+) cells were susceptible to infection but often resolved viremia and recovered fully from infection. Conditional IFNAR mice responded with a swift and strong CD8(+) T-cell response to viral infection, compared to a weak response in IFNAR(-/-) mice. Furthermore, mice lacking IFNAR on either CD11c(+) or LysM(+) cells were also sufficiently immunocompetent to raise a protective immune response to a candidate subunit vaccine against DENV-2. These data demonstrate that mice with conditional deficiencies in expression of the IFNAR represent improved models for the study of DENV immunology and screening of vaccine candidates.

IMPORTANCE

Dengue virus infects 400 million people every year worldwide, causing 100 million clinically apparent infections, which can be fatal if untreated. Despite many years of research, there are no effective vaccine and no antiviral treatment available for dengue. Development of vaccines has been hampered in particular by the lack of a suitable small animal model. Mouse models used to test dengue vaccine are deficient in interferon (IFN) type I signaling and severely immunocompromised and therefore likely not ideal for the testing of vaccines. In this study, we explored alternative models lacking the IFN receptor only on certain cell types. We show that mice lacking the IFN receptor on either CD11c- or LysM-expressing cells (conditional IFNAR mice) are susceptible to dengue virus infection. Importantly, we demonstrate that conditional IFN receptor knockout mice generate a better immune response to live virus and a candidate dengue vaccine compared to IFNAR mice and are resistant to subsequent challenge.

Increased expression of cytokines, soluble cytokine receptors, soluble apoptosis ligand and apoptosis in dengue

Several studies have been performed to determine biomarkers that define the risk factors to developing severe forms of dengue. In this study, the levels of TNF-α, IL-6, IL-1, IL-17, soluble interleukin-1 receptor like 1 protein (sST2), soluble TNF-related apoptosis-inducing ligand (sTRAIL), IL-12 and soluble receptors for TNF (sTNF-RI and sTNF-RII) were determined by ELISA in dengue patients and monocyte/macrophage cultures. Dengue was classified as dengue without warning symptoms (DNWS), with warning symptoms (DWWS) and severe dengue (SD). High values of IL-6, sTNFRI, sTNFRII and sST2 were observed in DWWS and/or SD and IL-12 and sTRAIL in DNWS. TNF-α and IL-17 were increased not associated to the disease severity. High production of TNF-α, IL-1β, IL-12, IL-17, sST2 and sTRAIL and apoptosis expression were observed in dengue monocyte/macrophage cultures. This study shows that beneficial or deleterious biomarkers can be present in dengue regardless the disease severity and that monocytes may be in part the source of studied molecules.

An emerging role for the anti-inflammatory cytokine interleukin-10 in dengue virus infection

Infection with dengue virus (DENV) causes both mild dengue fever and severe dengue diseases, such as dengue hemorrhagic fever and dengue shock syndrome. The pathogenic mechanisms for DENV are complicated, involving viral cytotoxicity, immunopathogenesis, autoimmunity, and underlying host diseases. Viral load correlates with disease severity, while the antibody-dependent enhancement of infection largely determines the secondary effects of DENV infection. Epidemiological and experimental studies have revealed an association between the plasma levels of interleukin (IL)-10, which is the master anti-inflammatory cytokine, and disease severity in patients with DENV infection. Based on current knowledge of IL-10-mediated immune regulation during infection, researchers speculate an emerging role for IL-10 in clinical disease prognosis and dengue pathogenesis. However, the regulation of dengue pathogenesis has not been fully elucidated. This review article discusses the regulation and implications of IL-10 in DENV infection. For future strategies against DENV infection, manipulating IL-10 may be an effective antiviral treatment in addition to the development of a safe dengue vaccine.

High Serum Levels of the Interleukin-33 Receptor Soluble ST2 as a Negative Prognostic Factor in Hepatocellular Carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common primary malignant liver tumor, usually arises in the setting of liver cirrhosis (LC), and has a poor prognosis. The recently discovered Th2-cytokine interleukin-33 (IL-33) is a possible mediator in pancreatic and gastric carcinogeneses. IL-33 binds to its receptor and to soluble ST2 (sST2), which thereby acts as a regulator. The role of IL-33 and sST2 in HCC has not been elucidated yet.

METHODS

We conducted a case-control study with 130 patients and 50 healthy controls (HCs). Sixty-five patients suffered from HCC and 65 patients had LC without HCC. We assessed serum IL-33 and sST2 levels and their association with established prognostic scores, liver function parameters, and overall survival (OS).

RESULTS

No significant difference in IL-33 serum levels was found in HCC compared to LC and HCs. IL-33 levels did not correlate with OS, liver function parameters, the Model for End-Stage Liver Disease (MELD) score, or the Cancer of the Liver Italian Program (CLIP) score. sST2 levels were significantly elevated in LC and HCC patients compared to HCs (P < .0001). Mean sST2 levels in LC were higher than in HCC (P < .0001), but a significant association with OS was only observed in the HCC group (P = .003). sST2 in HCC correlated with the CLIP score, the MELD score, and liver function parameters.

CONCLUSION

In the present study, the serum concentration of sST2 was associated with OS of HCC. Therefore, sST2 may be considered as a new prognostic marker in HCC and is worth further evaluation.

High plasma levels of soluble ST2 but not its ligand IL-33 is associated with severe forms of pediatric dengue

Identification of early determinants of dengue disease progression, which could potentially enable individualized patient care are needed at present times. Soluble ST2 (sST2) has been recently reported to be elevated in the serum of children older than 2 years old and adults with dengue infection and it was correlated with secondary infections as well as with severe presentations of the disease. The mechanism by which secreted ST2 is linked to severe dengue and plasma leakage remains unclear. One possibility is that IL-33 ligand may be elevated, contributing to membrane bound ST2 as part of the immune activation in dengue infection. We determined plasma levels of sST2 and the ligand IL-33 in 66 children with acute secondary dengue infections clinically classified using the guidelines of the World Health Organization, 2009. Dengue infection showed significant increases in cytokines IL-12p70, IL-10, IL-8, IL-6, IL-1β and TNFα measured by flow cytometry based assay compared to uninfected individuals. In contrast, IL-33 levels remained unchanged between infected and uninfected individuals. The levels of sST2 positively correlated with values of IL-6 and IL-8 and inversely correlated with number of median value of platelet levels. In addition to circulating cytokine positive correlations we found that sST2 and isoenzyme creatine kinase-MB (CK-MB), a marker of myocardial muscle damage present in severe dengue cases were associated. Our pediatric study concluded that in dengue infections sST2 elevation does not involve concomitant changes of IL-33 ligand. We propose a study to assess its value as a predictor factor of disease severity.

The evolutionary role of the IL-33/ST2 system in host immune defence

Interleukin (IL)-33 is a recently identified pleiotropic cytokine, which can orchestrate complex innate and adaptive immune responses in immunity and disease. It has been characterized as a cytokine of the IL-1 family and affects a wide range of immune cells by signalling through its receptor ST2L. Accumulating evidence suggests a crucial role of IL-33/ST2 in inducing and modifying host immune responses against a variety of pathogens including parasites, bacteria, viruses and fungi as well as sterile insults of both endogenous and exogenous source. In this review, we endeavour to give a comprehensive overview of the current knowledge about the role of IL-33 and its receptor ST2 in host defence against infections.

Dengue and soluble mediators of the innate immune system

Huge emphasis has been placed on the role of the adaptive immune system in dengue pathogenesis. Yet there is increasing evidence for the importance of the innate immune system in regulating dengue infection and possibly influencing the disease. This review focuses on the interplay between the innate immune system and dengue and highlights the role of soluble immunological mediators. Type I and type II interferons of the innate immune system demonstrate non-overlapping roles in dengue infection. Furthermore, while some IFN responses to dengue are protective, others may exert disease-related effects on the host. But aside from interferons, a number of cytokines have also been implicated in dengue pathogenesis. Our expanding knowledge of cytokines indicates that these soluble mediators act upon a complicated network of events to provoke the disease. This cytokine storm is generally attributed to massive T cell activation as an outcome of secondary infection. However, there is reason to believe that innate immune response-derived cytokines also have contributory effects, especially in the context of severe cases of primary dengue infection. Another less popular but interesting perspective on dengue pathogenesis is the effect of mosquito feeding on host immune responses and viral infection. Various studies have shown that soluble factors from vector saliva have the capacity to alter immune reactions and thereby influence pathogen transmission and establishment. Hence, modulation of the innate immune system at various levels of infection is a critical component of dengue disease. In the absence of an approved drug or vaccine for dengue, soluble mediators of the innate immune system could be a strategic foothold for developing anti-viral therapeutics and improving clinical management.

ST2 and IL-33 in pregnancy and pre-eclampsia

Normal pregnancy is associated with a mild systemic inflammatory response and an immune bias towards type 2 cytokine production, whereas pre-eclampsia is characterized by a more intense inflammatory response, associated with endothelial dysfunction and a type 1 cytokine dominance. Interleukin (IL)-33 is a newly described member of the IL-1 family, which binds its receptor ST2L to induce type 2 cytokines. A soluble variant of ST2 (sST2) acts as a decoy receptor to regulate the activity of IL-33. In this study circulating IL-33 and sST2 were measured in each trimester of normal pregnancy and in women with pre-eclampsia. While IL-33 did not change throughout normal pregnancy, or between non-pregnant, normal pregnant or pre-eclamptic women, sST2 was significantly altered. sST2 was increased in the third trimester of normal pregnancy (p<0.001) and was further increased in pre-eclampsia (p<0.001). This increase was seen prior to the onset of disease (p<0.01). Pre-eclampsia is a disease caused by placental derived factors, and we show that IL-33 and ST2 can be detected in lysates from both normal and pre-eclampsia placentas. ST2, but not IL-33, was identified on the syncytiotrophoblast layer, whereas IL-33 was expressed on perivascular tissue. In an in vitro placental perfusion model, sST2 was secreted by the placenta into the 'maternal' eluate, and placental explants treated with pro-inflammatory cytokines or subjected to hypoxia/reperfusion injury release more sST2, suggesting the origin of at least some of the increased amounts of circulating sST2 in pre-eclamptic women is the placenta. These results suggest that sST2 may play a significant role in pregnancies complicated by pre-eclampsia and increased sST2 could contribute to the type 1 bias seen in this disorder.

Statins reduce dengue virus production via decreased virion assembly

BACKGROUND

Most of the effects of statins can be explained by pleiotropic effects independent of their lowering of serum cholesterol; in some cases, these effects have been shown to be a result of the role of statins in the prenylation of cellular proteins, some of which are involved in the life cycle of animal viruses. This study evaluated the potential antiviral activity of lovastatin (LOV) against dengue virus (DENV) infection of epithelial and endothelial cells (VERO cells, epithelial cells derived from African green monkey kidney, and HMEC-1 cells, human dermal microvascular endothelial cells).

METHODS

To evaluate its potential antiviral effects, LOV was used before, during and after inoculation of cell cultures with DENV.

RESULTS

Before and after viral inoculation, LOV caused a reduction in virus yield (80% for HMECs and 25% for VERO cells). However, with LOV treatment after inoculation induced a marked increase (2- to 9-fold) in viral-positive RNA while the amount of viral protein increased only by 13-23%. A moderate reduction (1 log unit) in viral titer occurred concurrent with the increase in DENV genomic RNA and protein within the cells.

CONCLUSIONS

According to our results, LOV appears to have a greater effect on viral assembly than on replication, resulting in the cellular presence of viral genomic RNA and proteins that fail to take the normal assembly pathway.