Insights into potential causes of vascular hyperpermeability in dengue

Immune and vascular modulation by HERVs: the role of CXCR1 and IL18RAP in dengue severity progression

Introduction

Human Endogenous Retroviruses (HERVs), which can be activated by viral infections, have complex roles in gene regulation and immune modulation. However, their contribution to disease progression is not yet fully understood. Dengue fever ranges from mild symptoms to severe cases characterized by plasma leakage and immune dysregulation, providing a relevant context to investigate these interactions.

Methods

This study comes up with a comprehensive analysis of differentially expressed HERVs (DE-HERVs), protein-coding genes (DEGs), and regulatory elements such as microRNAs (DE-miRNA) and non-LTR retroviruses (DE-LINEs and DE-SINEs) derived from the transcriptomes of Brazilian dengue patients across different disease stages.

Results

The results show that DE-HERVs are associated with key genes identified in severe dengue cases, including ARG1, SLC15A2, COL3A1, SVEP1, CH25H, CST7, CXCR1, IL18RAP, SORL1, and TACR1, suggesting their role in immune modulation and endothelial permeability. Specifically, the upregulation of CXCR1 and IL18RAP genes in patients who progressed to severe dengue correlates with a complex regulatory network involving down-regulated microRNAs (miRNAs) and non-LTR retroviruses, emphasizing their relevance to inflammation and vascular permeability. MicroRNAs and non-LTR retroviruses were found to regulate these genes differently across dengue stages, with non-LTR elements appearing predominantly in non-severe cases and miRNA expression profiles varying across the comparison groups.

Discussion

These findings improve our understanding of the molecular mechanisms underlying dengue progression and suggest that HERV-related regulatory networks may influence viral infections. Further research is required to clarify the specific roles of HERVs in dengue pathogenesis.

Characterization of dengue patients in Vietnam: Clinical, virological, and IL-10 profiles during 2021- 2022 outbreaks

BACKGROUND

The pathogenesis of dengue is attributed to a complex interaction between the dengue virus (DENV) and the host immune system. The aim of this study is to investigate the clinical, virological, and Interleukin-10 (IL-10) profiles of dengue patients in Vietnam from two consecutive outbreaks in 2021 and 2022.

METHODS

A total of n=306 dengue patients were examined, who were clinically stratified according to dengue without warning signs (DF; n=178), dengue with warning signs (DWS; n=115) and severe dengue (SD; n=13). Patients were screened for dengue, Zika and chikungunya viruses. DENV were subjected to serotype specific real-time RT-PCR. Interleukin-10 (IL-10) levels were measured by ELISA, and IL-10 promoter variants (-1082G/A; -819C/T; -592C/A) were genotyped by direct Sanger sequencing to determine a possible association with susceptibility to dengue and disease severity.

RESULTS

No chikungunya or Zika viruses were detected. Patients were infected by one of the three different DENV serotypes (DENV-1, -2, -4). Plasma IL-10 levels were significantly elevated in patients (DF vs. DWS, p=0.004; DF vs. SD, p=0.001; DWS vs. SD, p=0.015). While the IL-10 allele -819C contributed to an increased risk of dengue (OR = 1.5, 95% CI = 1.1-2.0, p=0.04), genotype -1082GA showed a protective role against the disease (OR = 0.45, 95% CI = 0.27-0.72, p=0.009), and allele -1082G showed a protective role against DWS (OR = 0.44, 95% CI = 0.22-0.81, p=0.049). Also, the IL-10 GTA (-1082G/-819T/-592A) haplotype was observed to confer protection (OR = 0.31, 95% CI = 0.14-0.67, p< 0.003).

CONCLUSION

While DENV-1 and DENV-2 were the predominant serotypes in circulation, plasma IL-10 levels and IL-10 promoter variants were also significantly associated with dengue and its severity.

Induction of PD-1 and CD44 in CD4+ T cells by circulatory extracellular vesicles from severe dengue patients drives endothelial damage via the NF-kB signaling pathway

Extracellular vesicles (EVs) emerged as critical contributors to the pathogenesis of vascular endothelial barrier dysfunction during the inflammatory response to infection. However, the contribution of circulating EVs to modifying endothelial function during dengue virus infection remains unclear. In this study, we showed that severe dengue patients' plasma-derived EV (SD-EV) were found to carry elevated levels of different protein cargos, e.g., immunoregulatory proteins (PD-L1, CD44). Further, we demonstrated that SD-EV induces PD-1 and CD44 expression on CD4+ T cells. SD-EV-modulated CD4+ T (SD-EV-CD4) cells released secretome delayed endothelial cell (EC) migration, arrested them in the G1 phase, and augmented the expression of PD-L1 and ICAM-1 expression on EC through the Notch signaling pathway. Blocking SD-EV and CD4+ T-cell interaction through the PD-1/PD-L1 pathway partially rescued the CD4+ T cell's effect on EC but did not alter ICAM-1 expression on EC. We observed that the ICAM-1 expression on EC and hyaluronic acid (HA) release from EC was mediated by CD44, which was elevated on SD-EV-modulated CD4+ T cells (SD-EV-CD4), indicating a permeability defect. Blocking of CD44 on SD-EV-CD4 significantly reduced ICAM-1 expression on EC. Further, depletion of specific cytokines, e.g., TNF-α and not IFN-γ from the SD-EV-CD4 secretome, reduced ICAM-1 expression, decreased transendothelial electrical resistance, and induced apoptosis on EC significantly. Treatment with NF-kB inhibitor before secretome addition to EC reduced ICAM-1 expression on EC. In conclusion, we provided evidence that SD-EV-CD4 carrying PD-1 and CD44, when interacting with EC, significantly affected endothelial cell properties and may be significant in dengue-mediated endothelial dysfunction.IMPORTANCEExtracellular vesicles (EVs) are small membrane vesicles secreted into biological fluids, including plasma from living cells, holding insights into pathological processes. Studying EVs under pathological conditions is extremely important as they play a selective role in intercellular communication and modulation of immune response under diverse pathological conditions. However, there is less clarity on how circulatory extracellular vesicles influence immune cells during dengue virus (DV) infection and impact pathogenesis. Our present study highlights the impact of severe dengue patients' plasma-derived EV (SD-EV) on CD4+ T cells and together induce endothelial barrier dysfunction. We provided evidence that SD-EV induces PD-1 and CD44 on CD4+ T cells and, when interacting with endothelial cells (EC), drives endothelial damage through direct interaction or secretome and may be significant in dengue-mediated endothelial dysfunction.

Neutrophils - an understudied bystander in dengue?

Dengue is a mosquito-borne viral disease which causes significant morbidity and mortality each year. Previous research has proposed several mechanisms of pathogenicity that mainly involve the dengue virus and host humoral immunity. However, innate immune cells, such as neutrophils, may also play an important role in dengue, albeit a much less defined role. In this review, we discuss the emerging roles of neutrophils in dengue and their involvement in pathologies associated with severe dengue. We also describe the potential use of several neutrophil proteins as biomarkers for severe dengue. These studies suggest that neutrophils are important players in dengue, and a better understanding of neutrophil-dengue biology is urgently needed.

An effective pan-serotype dengue vaccine and enhanced control strategies could help in reducing the severe dengue burden in Bangladesh-A perspective

Dengue is an important vector-borne disease occurring globally. Dengue virus (DENV) infection can result in a potentially life-threatening disease. To date, no DENV-specific antiviral treatment is available. Moreover, an equally effective pan-serotype dengue virus vaccine is not available. Recently, two DENV vaccines, Dengvaxia and Qdenga, were licensed for limited use. However, none of them have been approved in Bangladesh. DENV is transmitted by Aedes mosquitoes, and global warming caused by climate change favoring Aedes breeding plays an important role in increasing DENV infections in Bangladesh. Dengue is a serious public health concern in Bangladesh. In the year 2023, Bangladesh witnessed its largest dengue outbreak, with the highest number of dengue cases (n = 321,179) and dengue-related deaths (n = 1,705) in a single epidemic year. There is an increased risk of severe dengue in individuals with preexisting DENV-specific immunoglobulin G if the individuals become infected with different DENV serotypes. To date, vector control has remained the mainstay for controlling dengue; therefore, an immediate, strengthened, and effective vector control program is critical and should be regularly performed for controlling dengue outbreaks in Bangladesh. In addition, the use of DENV vaccine in curbing dengue epidemics in Bangladesh requires more consideration and judgment by the respective authority of Bangladesh. This review provides perspectives on the control and prevention of dengue outbreaks. We also discuss the challenges of DENV vaccine use to reduce dengue epidemics infection in Bangladesh.

Within-host models unravelling the dynamics of dengue reinfections

Caused by four serotypes, dengue fever is a major public health concern worldwide. Current modeling efforts have mostly focused on primary and heterologous secondary infections, assuming that lifelong immunity prevents reinfections by the same serotype. However, recent findings challenge this assumption, prompting a reevaluation of dengue immunity dynamics. In this study, we develop a within-host modeling framework to explore different scenarios of dengue infections. Unlike previous studies, we go beyond a deterministic framework, considering individual immunological variability. Both deterministic and stochastic models are calibrated using empirical data on viral load and antibody (IgM and IgG) concentrations for all dengue serotypes, incorporating confidence intervals derived from stochastic realizations. With good agreement between the mean of the stochastic realizations and the mean field solution for each model, our approach not only successfully captures primary and heterologous secondary infection dynamics facilitated by antibody-dependent enhancement (ADE) but also provides, for the first time, insights into homotypic reinfection dynamics. Our study discusses the relevance of homotypic reinfections in dengue transmission at the population level, highlighting potential implications for disease prevention and control strategies.

The Dynamic Relationship between Dengue Virus and the Human Cutaneous Innate Immune Response

Dengue virus (DENV) is a continuing global threat that puts half of the world's population at risk for infection. This mosquito-transmitted virus is endemic in over 100 countries. When a mosquito takes a bloodmeal, virus is deposited into the epidermal and dermal layers of human skin, infecting a variety of permissive cells, including keratinocytes, Langerhans cells, macrophages, dermal dendritic cells, fibroblasts, and mast cells. In response to infection, the skin deploys an array of defense mechanisms to inhibit viral replication and prevent dissemination. Antimicrobial peptides, pattern recognition receptors, and cytokines induce a signaling cascade to increase transcription and translation of pro-inflammatory and antiviral genes. Paradoxically, this inflammatory environment recruits skin-resident mononuclear cells that become infected and migrate out of the skin, spreading virus throughout the host. The details of the viral-host interactions in the cutaneous microenvironment remain unclear, partly due to the limited body of research focusing on DENV in human skin. This review will summarize the functional role of human skin, the cutaneous innate immune response to DENV, the contribution of the arthropod vector, and the models used to study DENV interactions in the cutaneous environment.

Febrile Phase Soluble Urokinase Plasminogen Activator Receptor and Olfactomedin 4 as Prognostic Biomarkers for Severe Dengue in Adults

BACKGROUND

Dengue cases continue to rise and can overwhelm healthcare systems during outbreaks. In dengue, neutrophil mediators, soluble urokinase plasminogen activator receptor (suPAR) and olfactomedin 4, and mast cell mediators, chymase and tryptase, have not been measured longitudinally across the dengue phases. The utility of these proteins as prognostic biomarkers for severe dengue has also not been assessed in an older adult population.

METHODS

We prospectively enrolled 99 adults with dengue-40 dengue fever, 46 dengue with warning signs and 13 severe dengue, along with 30 controls. Plasma levels of suPAR, olfactomedin 4, chymase and tryptase were measured at the febrile, critical and recovery phases in dengue patients.

RESULTS

The suPAR levels were significantly elevated in severe dengue compared to the other dengue severities and controls in the febrile (P < .001), critical (P < .001), and recovery (P = .005) phases. In the febrile phase, suPAR was a prognostic biomarker of severe dengue, with an AUROC of 0.82. Using a cutoff derived from Youden's index (5.4 ng/mL) and an estimated prevalence of severe dengue (16.5%) in our healthcare institution, the sensitivity was 71.4% with a specificity of 87.9% in the febrile phase, and the positive and negative predictive values were 54.7% and 95.8%, respectively. Olfactomedin 4 was elevated in dengue patients but not in proportion to disease severity in the febrile phase (P = .04) There were no significant differences in chymase and tryptase levels between dengue patients and controls.

CONCLUSIONS

In adult dengue, suPAR may be a reliable prognostic biomarker for severe dengue in the febrile phase.

Severe dengue infection unmasking drug-induced liver injury: Successful management with N-acetylcysteine

Key Clinical Message

Clinicians in tuberculosis and dengue endemic regions should have heightened vigilance for drug-induced liver injury (DILI) overlapping with active infections, enabling prompt recognition and life-saving conservative management.

Abstract

Severe dengue and drug-induced liver injury (DILI) are significant independent risk factors for acute liver failure. The co-occurrence of these conditions significantly complicates clinical management. Here, we describe the case of a 21-year-old Nepali female who developed acute liver failure during antitubercular therapy (ATT). The patient, presenting with fever and nausea after 3 weeks of ATT, subsequently received a diagnosis of severe dengue. Laboratory evidence indicated markedly elevated transaminases (AST 4335 U/L, ALT 1958 U/L), total bilirubin (72 μmol/L), and INR (>5). Prompt discontinuation of first-line ATT, initiation of a modified ATT regimen, and N-acetylcysteine (NAC) infusion facilitated the patient's recovery after a week of intensive care. This case underscores the potential for synergistic hepatotoxicity in regions where multiple endemic illnesses coincide. Early recognition of DILI, cessation of offending agents, and comprehensive intensive care are crucial interventions. While the definitive efficacy of NAC remains under investigation, its timely administration in these complex cases warrants exploration for its potential lifesaving benefits.

Recent Dengue Infection in Bangladesh: A Seasonal Endemic Progressing to Year-long Serious Health Concern

Dengue represents one of the most dangerous mosquito-borne viral diseases. Although the disease has been prevalent around the globe over the centuries, recent outbreaks of dengue have devasted the healthcare delivery system of many countries. Being a global infection, dengue virus (DENV) is endemically present mainly in Latin America and Caribbean countries as well as countries in South Asia. The recent outbreak of DENV infection has indicated an exceptional outbreak of DENV in some countries in South Asia. There has been a serious endemic of DENV during 2019. After a heterogeneous pause, another severe outbreak of DENV was reported in some Asian countries in 2023. Among the Asian countries, Bangladesh has reported an acute upsurge of DENV infection in 2023 with record numbers of fatalities. However, this pattern of DENV has not been detected in neighbors of Bangladesh, such as India or other countries in Southeast Asia. This provides an emergent task of dissecting the present DENV infection in Bangladesh from different angles to get insights for future containment of the DENV infection, not only in Bangladesh but also in other DENV endemic areas or DENV-native areas.

How to cite this article

Akbar SMF, Khan S, Mahtab M, et al. Recent Dengue Infection in Bangladesh: A Seasonal Endemic Progressing to Year-long Serious Health Concern. Euroasian J Hepato-Gastroenterol 2023;13(2):145-151.

Myeloperoxidase inhibition may protect against endothelial glycocalyx shedding induced by COVID-19 plasma

BACKGROUND

SARS-CoV-2, the causative agent of COVID-19, is a threat to public health. Evidence suggests increased neutrophil activation and endothelial glycocalyx (EG) damage are independently associated with severe COVID-19. Here, we hypothesised that an increased level of blood neutrophil myeloperoxidase (MPO) is associated with soluble EG breakdown, and inhibiting MPO activity may reduce EG damage.

METHODS

Analysing a subset of acute and convalescent COVID-19 plasma, 10 from severe and 15 from non-severe COVID-19 cases, and 9 from pre-COVID-19 controls, we determined MPO levels, MPO activity and soluble EG proteins (syndecan-1 and glypican-1) levels by enzyme-linked immunosorbent assay. In vitro primary human aortic endothelial cells were cultured with plasma untreated or treated with specific MPO inhibitors (MPO-IN-28, AZD5904) to determine EG shedding. We then investigated whether inhibiting MPO activity decreased EG degradation.

RESULTS

In COVID-19 plasma, MPO levels, MPO activity and levels of soluble EG proteins are significantly raised compared to controls, and concentrations increase in proportion to disease severity. Despite clinical recovery, protein concentrations remain significantly elevated. Interestingly, there is a trend of increasing MPO activity in convalescent plasma in both severe and non-severe groups. MPO levels and MPO activity correlate significantly with soluble EG levels and inhibiting MPO activity leads to reduced syndecan-1 shedding, in vitro.

CONCLUSIONS

Neutrophil MPO may increase EG shedding in COVID-19, and inhibiting MPO activity may protect against EG degradation. Further research is needed to evaluate the utility of MPO inhibitors as potential therapeutics against severe COVID-19.

Association of Neutrophil Mediators With Dengue Disease Severity and Cardiac Impairment in Adults

BACKGROUND

Cardiac impairment contributes to hypotension in severe dengue (SD). However, studies examining pathogenic factors affecting dengue-associated cardiac impairment are lacking. We examined the role of neutrophil mediators on cardiac impairment in clinical dengue.

METHODS

We prospectively enrolled adult patients with dengue and controls. Cardiac parameters were measured using a bioimpedance device. Neutrophils mediators were measured, including myeloperoxidase (MPO) and citrullinated histone H3.

RESULTS

We recruited 107 dengue patients and 30 controls. Patients with dengue were classified according to World Health Organization 2009 guidelines (44 with dengue fever [DF], 51 with DF with warning signs, and 12 with SD). During critical phase, stroke index (P < .001), cardiac index (P = .03), and Granov-Goor index (P < .001) were significantly lower in patients with dengue than in controls. During critical phase, MPO was significantly higher in patients with dengue than in controls (P < .001) and also significantly higher in patients with SD than in those with DF. In addition, MPO was inversely associated with the stroke, cardiac, and Granov-Goor indexes, during the critical phase, and longitudinally as well.

CONCLUSIONS

Cardiac function was decreased, and MPO increased, during with critical phase in patients SD compared with those with DF and controls. MPO may mediate dengue-associated cardiac impairment.

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.

Serum levels of matrix metalloproteinases as prognostic markers for severe dengue with plasma leakage

BACKGROUND

Plasma leakage is a major pathogenic manifestation of severe dengue and is a precursor of life-threatening complications associated with dengue. Accumulating evidence indicates the role of Matrix Metalloproteinases (MMPs) in mediating vascular permeability and plasma leakage following induction by the dengue virus. This study aims to investigate the utility of MMP-2, MMP-3, and MMP-9 in predicting the severity of dengue infection and further explore the relationship of these markers with the pathogenic factors associated with plasma leakage.

METHODS

The dengue-positive subjects were classified into mild and severe dengue groups based on the manifestation of warning signs. The samples in each group and healthy controls were quantified for basic laboratory characteristics. The levels of MMP-2, MMP-3, MMP-9, and Macrophage migration inhibitory factor (MIF) were estimated in all serum samples using a multiplex bead-based assay.

RESULTS

MMP-2 and MMP-9 were markedly elevated in severe dengue patients compared to mild dengue patients and healthy controls. No alteration in the circulating levels of MMP-3 was observed between the study groups. ROC curve analysis indicated that MMP-2 and MMP-9 exhibited good potential for predicting severe dengue. Notably, an increase in MMP-9 was associated with increased MIF and Hematocrit levels in severe dengue patients.

CONCLUSION

MMP-2 and MMP-9 could serve as prognostic biomarkers for severe dengue. These findings also identify the association of MMP-9 with markers of plasma leakage, thereby encouraging further studies to explore the therapeutic potential of targeting MMP-9 in managing plasma leakage in severe dengue.