Decreased Type I Interferon Production by Plasmacytoid Dendritic Cells Contributes to Severe Dengue

Cytokine and chemokine kinetics in natural human dengue infection as predictors of disease outcome

Dengue is an important tropical disease with considerable global impact. Despite this, there remains an urgent need for reliable biomarkers to predict disease severity, as well as effective antiviral drugs and targeted treatments. In this study, we conducted a comprehensive profiling of 41 plasma mediators in patients with asymptomatic dengue (AD) and symptomatic dengue (SD), which includes mild dengue fever (DF) and severe dengue hemorrhagic fever (DHF). Our findings revealed that the levels of nearly all measured mediators were consistently lower in AD compared to SD patients, suggesting a potential protective cytokine response signature. Time-course cytokine analysis in SD shown significantly elevated levels of pro-inflammatory cytokines and chemokines associated with inflammation and viral clearance upon the acute phase, while various growth factors were elevated during the convalescence. Notably, we identified elevated IL-15 levels in DHF patients three days before fever subsidence, highlighting its potential as an early prognostic biomarker for severe disease outcomes. Furthermore, prolonged high levels of IL-8 and IP-10 in DHF during the critical period may contribute to dengue immunopathogenesis. This study advances the understanding of cytokine dynamics in the natural course of human dengue infection, providing valuable insights for the development of targeted treatments and prognostic biomarkers.

Quantifying temporal differences in the induction of interferon-mediated signalling observed in a dengue virus 1 human infection model: insights from longitudinal proteome analysis

BACKGROUND

According to WHO, dengue is one of the top ten global health threats, with almost half of the world's population at risk of being infected. Most of the annual 400 million dengue virus (DENV) infections manifest asymptomatically or in a mild form, causing symptoms such as fever and headache. Nevertheless, every year 500,000 dengue cases require hospitalization and up to 25,000 patients die. Despite the high incidence, the DENV-elicited proteome response remains insufficiently understood.

METHODS

Therefore, we evaluated the proteome dynamics of nine dengue-naïve individuals experimentally infected with the underattenuated DENV-1 strain 45AZ5 via the Proximity Extension Assay technology of Olink®.

FINDINGS

Using Olink Explore, a total of ∼3000 proteins were quantified simultaneously in serum samples at 8, 10, 14, and 28 days after the viral inoculation. We identified the top ten significant proteins via linear mixed effects models, i.e., interferons (IFNs), IFN-related proteins, and members of the CCL and CXCL chemokine family. In all participants, an increase in IFN-λ1 levels was observed after peak viral load, whereas in one participant an IFN-γ response was not detected. Interestingly, both the onset and peak viral load of this participant were, on average, delayed 4 days compared to other participants. To gain a detailed kinetic overview of the DENV-elicited proteome response, we designed a smaller, targeted Olink® panel to evaluate serum protein levels at multiple time points throughout the infection. Here, we revealed that type I/III IFN response precedes the type II IFN response.

INTERPRETATION

In conclusion, our analyses provided detailed insights into the temporal dynamics of the different IFN responses upon a primary DENV-1 infection. These insights might aid in better understanding dengue pathogenesis.

FUNDING

Funding for this research was provided by Johnson and Johnson, the State of New York, and the Congressionally Directed Medical Research Programs.

Expression of interferon-stimulated genes, but not polymorphisms in the interferon α/β receptor 2 gene, is associated with coronavirus disease 2019 mortality

Excessive inflammatory response is a hallmark of severe COVID-19. This study investigated the associations between interferon-stimulated genes (ISGs) expression, genetic variation in the interferon α/β receptor 2 (IFNAR2) gene, and COVID-19 mortality. We investigated 67 patients with moderate-to-severe COVID-19. Of them, 22 patients (32.8 %) died because of COVID-19. We examined the expression of ISGs in total RNA of peripheral whole blood. We observed a significant increase in the expression of all ISGs examined in non-surviving patients, indicating a heightened interferon type I signaling activation in non-survived patients. Subsequently, we analyzed whether the increase in ISGs expression was correlated with polymorphism within the IFNAR2 gene. Intriguingly, no significant association was observed between IFNAR2 gene polymorphism and COVID-19 mortality. Similarly, no association was noted between the IFNAR2 and ISGs expression levels. Overall, our data showed that higher ISGs expression, which presumably indicates heightened interferon type I activation, is associated with COVID-19 mortality.

Molecular mechanisms in the pathogenesis of dengue infections

Dengue is the most rapidly emerging climate-sensitive infection, and morbidity/mortality and disease incidence are rising markedly, leading to healthcare systems being overwhelmed. There are currently no specific treatments for dengue or prognostic markers to identify those who will progress to severe disease. Owing to an increase in the burden of illness and a change in epidemiology, many patients experience severe disease. Our limited understanding of the complex mechanisms of disease pathogenesis has significantly hampered the development of safe and effective treatments, vaccines, and biomarkers. We discuss the molecular mechanisms of dengue pathogenesis, the gaps in our knowledge, and recent advances, as well as the most crucial questions to be answered to enable the development of therapeutics, biomarkers, and vaccines.

Age-related transcript changes in type I interferon signaling in children and adolescents with long COVID

SARS-CoV-2 typically causes mild symptoms in children, but evidence suggests that persistent immunopathological changes may lead to long COVID (LC). To explore the interplay between LC and innate immunity, we assessed the type I interferon (IFN-I) response in children and adolescents with LC symptoms (LC; n = 28). This was compared with age-matched SARS-CoV-2 recovered participants without LC symptoms (MC; n = 28) and healthy controls (HC; n = 18). We measured the mRNA expression of IFN-I (IFN-α/β/ε/ω), IFN-I receptor (IFNAR1/2), and ISGs (ISG15, ISG56, MxA, IFI27, BST2, LY6E, OAS1, OAS2, OAS3, and MDA5) in PBMCs collected 3-6 months after COVID-19. LC adolescents (12-17 years) had higher transcript levels of IFN-β, IFN-ε, and IFN-ω than HC, whereas LC children (6-11 years) had lower levels than HC. In adolescents, increased levels of IFN-α, IFN-β, and IFN-ω mRNAs were found in the LC group compared with MC, while lower levels were observed in LC children than MC. Adolescents with neurological symptoms had higher IFN-α/β mRNA levels than MC. LC and MC participants showed decreased expression of ISGs and IFNAR1, but increased expression of IFNAR2, than HC. Our results show age-related changes in the expression of transcripts involved in the IFN-I signaling pathway in children and adolescents with LC.

Antrodia cinnamomea Suppress Dengue Virus Infection through Enhancing the Secretion of Interferon-Alpha

Dengue caused by dengue virus (DENV) is a mosquito-borne disease. Dengue exhibits a wide range of symptoms, ranging from asymptomatic to flu-like illness, and a few symptomatic cases may develop into severe dengue, leading to death. However, there are no effective and safe therapeutics for DENV infections. We have previously reported that cytokine expression, especially inflammatory cytokines, was altered in patients with different severities of dengue. Antrodia cinnamomea (A. cinnamomea) is a precious and endemic medical mushroom in Taiwan. It contains unique chemical components and exhibits biological activities, including suppressing effects on inflammation and viral infection-related diseases. According to previous studies, megakaryocytes can support DENV infection, and the number of megakaryocytes is positively correlated with the viral load in the serum of acute dengue patients. In the study, we investigated the anti-DENV effects of two ethanolic extracts (ACEs 1-2) and three isolated compounds (ACEs 3-5) from A. cinnamomea on DENV infection in Meg-01 cells. Our results not only demonstrated that ACE-3 and ACE-4 significantly suppressed DENV infection, but also reduced interleukin (IL)-6 and IL-8 levels. Moreover, the level of the antiviral cytokine interferon (IFN)-α was also increased by ACE-3 and ACE-4 in Meg-01 cells after DENV infection. Here, we provide new insights into the potential use of A. cinnamomea extracts as therapeutic agents against DENV infection. However, the detailed mechanisms underlying these processes require further investigation.

Dengue virus co-opts innate type 2 pathways to escape early control of viral replication

Mast cell products and high levels of type 2 cytokines are associated with severe dengue disease. Group 2 innate lymphoid cells (ILC2) are type-2 cytokine-producing cells that are activated by epithelial cytokines and mast cell-derived lipid mediators. Through ex vivo RNAseq analysis, we observed that ILC2 are activated during acute dengue viral infection, and show an impaired type I-IFN signature in severe disease. We observed that circulating ILC2 are permissive for dengue virus infection in vivo and in vitro, particularly when activated through prostaglandin D2 (PGD2). ILC2 underwent productive dengue virus infection, which was inhibited through CRTH2 antagonism. Furthermore, exogenous IFN-β induced expression of type I-IFN responsive anti-viral genes by ILC2. PGD2 downregulated type I-IFN responsive gene and protein expression; and urinary prostaglandin D2 metabolite levels were elevated in severe dengue. Moreover, supernatants from activated ILC2 enhanced monocyte infection in a GM-CSF and mannan-dependent manner. Our results indicate that dengue virus co-opts an innate type 2 environment to escape early type I-IFN control and facilitate viral dissemination. PGD2 downregulates type I-IFN induced anti-viral responses in ILC2. CRTH2 antagonism may be a therapeutic strategy for dengue-associated disease.

Dengue and COVID-19: two sides of the same coin

BACKGROUND

Many countries in Asia and Latin America are currently facing a double burden of outbreaks due to dengue and COVID-19. Here we discuss the similarities and differences between the two infections so that lessons learnt so far from studying both infections will be helpful in further understanding their immunopathogenesis and to develop therapeutic interventions.

MAIN BODY

Although the entry routes of the SARS-CoV-2 and the dengue virus (DENV) are different, both infections result in a systemic infection, with some similar clinical presentations such as fever, headache, myalgia and gastrointestinal symptoms. However, while dengue is usually associated with a tendency to bleed, development of micro and macrothrombi is a hallmark of severe COVID-19. Apart from the initial similarities in the clinical presentation, there are further similarities between such as risk factors for development of severe illness, cytokine storms, endothelial dysfunction and multi-organ failure. Both infections are characterised by a delayed and impaired type I IFN response and a proinflammatory immune response. Furthermore, while high levels of potent neutralising antibodies are associated with protection, poorly neutralising and cross-reactive antibodies have been proposed to lead to immunopathology by different mechanisms, associated with an exaggerated plasmablast response. The virus specific T cell responses are also shown to be delayed in those who develop severe illness, while varying degrees of endothelial dysfunction leads to increased vascular permeability and coagulation abnormalities.

CONCLUSION

While there are many similarities between dengue and SARS-CoV-2 infection, there are also key differences especially in long-term disease sequelae. Therefore, it would be important to study the parallels between the immunopathogenesis of both infections for development of more effective vaccines and therapeutic interventions.

Immune and non-immune functions of adipose tissue leukocytes

Adipose tissue is a complex dynamic organ with whole-body immunometabolic influence. Much of the work into understanding the role of immune cells in adipose tissue has been in the context of obesity. These investigations have also uncovered a range of typical (immune) and non-typical functions exerted by adipose tissue leukocytes. Here we provide an overview of the adipose tissue immune system, including its role as an immune reservoir in the whole-body response to infection and as a site of parasitic and viral infections. We also describe the functional roles of specialized immunological structures found within adipose tissue. However, our main focus is on the recently discovered 'non-immune' functions of adipose tissue immune cells, which include the regulation of adipocyte homeostasis, as well as responses to changing nutrient status and body temperature. In doing so, we outline the therapeutic potential of the adipose tissue immune system in health and disease.

Increased serum IL-2, IL-4, IL-5 and IL-12p70 levels in AChR subtype generalized myasthenia gravis

Background

Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular junctions. Cytokines play important roles in facilitating the immune response and augmenting the pathogenic antibody production. The current study aims to sensitively characterize the serum levels of cytokines with very low concentration in generalized MG (gMG).

Methods

Using ultrasensitive single-molecule arrays (SIMOA), we measured serum IL-2, IL-4, IL-5 and IL-12p70 in 228 participants including 152 immunotherapy-naïve anti-acetylcholine receptor (AChR) subtype gMG from Huashan MG registry and 76 age-matched healthy controls. Subgroup analysis was then performed by stratifying patients according to the onset ages, MGFA classification, disease duration at baseline.

Results

Serum IL-2, IL-4, IL-5 and IL-12p70 levels were significantly elevated in gMG compared to controls (0.179 pg/mL versus 0.011 pg/mL, P < 0.0001; 0.029 pg/mL versus 0.018 pg/mL, P = 0.0259; 0.215 pg/mL versus 0.143 pg/mL, P = 0.0007; 0.132 pg/mL versus 0.118 pg/mL, P = 0.0401). Subgroup analysis revealed that IL-2 levels were slightly elevated in gMG with MGFA II compared to MGFA III/IV (0.195 pg/mL versus 0.160 pg/mL, P = 0.022), as well as elevated levels of IL-2 (0.220 pg/mL versus 0.159 pg/mL, P = 0.0002) and IL-5 (0.251 pg/mL versus 0.181 pg/mL, P = 0.004) in late-onset gMG compared with the early-onset gMG. gMG patients with a long duration had a significant increased serum IL-12p70 than those with a short duration (0.163 pg/mL versus 0.120 pg/mL, P = 0.011).

Conclusion

Serum IL-2, IL-4, IL-5 and IL-12p70 levels were increased in AChR subtype gMG using ultrasensitive measurement. Serum cytokines with very low concentrations may provide as potential biomarkers in stratifying gMG patients in future prospective cohort studies.

Differential effects of orally administered <i>Lactobacillus acidophilus</i> L-55 on the gene expression of cytokines and master immune switches in the ileum and spleen of laying hen with an attenuated Newcastle disease virus vaccine

This study aimed to evaluate the benefits of oral administration of Lactobacillus acidophilus strain L-55 (LaL-55) to chickens inoculated with a Newcastle disease virus (NDV)-based live-attenuated vaccine by examining the mRNA expression of several genes related to viral infection in the spleen and ileum by quantitative reverse transcription polymerase chain reaction. In the spleen, interferon (IFN)-α was significantly higher in the low- and middle-dose LaL-55 groups at 6 weeks than at 4 weeks. IFN regulatory factor (IRF)-3 and IRF-7 expression was significantly higher in the low-dose LaL-55 group than in the middle- and high-dose LaL-55 groups. In the ileum, melanoma differentiation-associated gene 5 showed a dose-dependent increase at 4 weeks. IFN-γ and IRF-7 showed dose-dependent increases at 6 weeks. These results suggested that LaL-55 boosts the immune response to the NDV vaccine, albeit by different mechanisms in the spleen and ileum.

Lactococcus lactis Strain Plasma Intake Suppresses the Incidence of Dengue Fever-like Symptoms in Healthy Malaysians: A Randomized, Double-Blind, Placebo-Controlled Trial

Dengue fever (DF) is a mosquito-borne disease still with no effective treatment or vaccine available. A randomized, placebo-controlled, double-blinded, parallel-group trial was undertaken to evaluate the efficacy of oral intake of Lactococcus lactis strain plasma (LC-Plasma) on the presentation and severity of DF-like symptoms among healthy volunteers. Study participants (320) were assigned into two groups, and consumed either placebo or LC-Plasma tablets (approximately 100 billion cells/day) for 8 weeks. The clinical symptoms of DF were self-recorded through questionnaires, and exposure to DENV was determined by serum antibody and/or DENV antigen tests. No significant differences between groups were observed for exposure to DENV, or the symptomatic ratio. Results obtained showed that participants from the LC-Plasma group reported a significant reduction in the cumulative incidence days of DF-like symptoms, which include fever (p < 0.001), muscle pain (p < 0.005), joint pain (p < 0.001), and pain behind the eyes (p < 0.001), compared to that of the placebo group. Subgroup analysis revealed a significantly (p < 0.05) reduced severity score in the LC-Plasma group when study sites were separately analyzed. Overall, our findings suggest that LC-Plasma supplementation reduces the cumulative days with DF-like symptoms, and the severity of the symptoms. Daily oral intake of LC-Plasma, hence, is shown to mitigate the DF-like symptoms.

Differential levels of IFNα subtypes in autoimmunity and viral infection

Type I interferons are essential for host response to viral infections, while dysregulation of their response can result in autoinflammation or autoimmunity. Among IFNα (alpha) responses, 13 subtypes exist that signal through the same receptor, but have been reported to have different effector functions. However, the lack of available tools for discriminating these closely related subtypes, in particular at the protein level, has restricted the study of their differential roles in disease. We developed a digital ELISA with specificity and high sensitivity for the IFNα2 subtype. Application of this assay, in parallel with our previously described pan-IFNα assay, allowed us to study different IFNα protein responses following cellular stimulation and in diverse patient cohorts. We observed different ratios of IFNα protein responses between viral infection and autoimmune patients. This analysis also revealed a small percentage of autoimmune patients with high IFNα2 protein measurements but low pan-IFNα measurements. Correlation with an ISG score and functional activity showed that in this small sub group of patients, IFNα2 protein measurements did not reflect its biological activity. This unusual phenotype was partly explained by the presence of anti-IFNα auto-antibodies in a subset of autoimmune patients. This study reports ultrasensitive assays for the study of IFNα proteins in patient samples and highlights the insights that can be obtained from the use of multiple phenotypic readouts in translational and clinical studies.

Viral-induced inflammatory coagulation disorders: Preparing for another epidemic

A number of viral infectious diseases have emerged or reemerged from wildlife vectors that have generated serious threats to global health. Increased international traveling and commerce increase the risk of transmission of viral or other infectious diseases. In addition, recent climate changes accelerate the potential spread of domestic disease. The Coronavirus disease 2019 (COVID-19) pandemic is an important example of the worldwide spread, and the current epidemic will unlikely be the last. Viral hemorrhagic fevers, such as Dengue and Lassa fevers, may also have the potential to spread worldwide with a significant impact on public health with unpredictable timing. Based on the important lessons learned from COVID-19, it would be prudent to prepare for future pandemics of life-threatening viral diseases. Among the various threats, this review focuses on the coagulopathy of acute viral infections since hypercoagulability has been a major challenge in COVID-19, but represents a different presentation compared to viral hemorrhagic fever. However, both thrombosis and hemorrhage are understood as the result of thromboinflammation due to viral infections, and the role of anticoagulation is important to consider.