Plasma levels of inter-alpha inhibitor proteins in children with acute Dengue virus infection

Novel aspects of sepsis pathophysiology: NETs, plasma glycoproteins, endotheliopathy and COVID-19

In 2016, sepsis was newly defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis remains one of the crucial medical problems to be solved worldwide. Although the world health organization has made sepsis a global health priority, there remain no specific and effective therapy for sepsis so far. Indeed, over the previous decades almost all attempts to develop novel drugs have failed. This may be partly ascribable to the multifactorial complexity of the septic cascade and the resultant difficulties of identifying drug targets. In addition, there might still be missing links among dysregulated host responses in vital organs. In this review article, recent advances in understanding of the complex pathophysiology of sepsis are summarized, with a focus on neutrophil extracellular traps (NETs), the significant role of NETs in thrombosis/embolism, and the functional roles of plasma proteins, histidine-rich glycoprotein (HRG) and inter-alpha-inhibitor proteins (IAIPs). The specific plasma proteins that are markedly decreased in the acute phase of sepsis may play important roles in the regulation of blood cells, vascular endothelial cells and coagulation. The accumulating evidence may provide us with insights into a novel aspect of the pathophysiology of sepsis and septic ARDS, including that in COVID-19.

Modulation of hyaluronan signaling as a therapeutic target in human disease

The extracellular matrix is an active participant, modulator and mediator of the cell, tissue, organ and organismal response to injury. Recent research has highlighted the role of hyaluronan, an abundant glycosaminoglycan constituent of the extracellular matrix, in many fundamental biological processes underpinning homeostasis and disease development. From this basis, emerging studies have demonstrated the therapeutic potential of strategies which target hyaluronan synthesis, biology and signaling, with significant promise as therapeutics for a variety of inflammatory and immune diseases. This review summarizes the state of the art in this field and discusses challenges and opportunities in what could emerge as a new class of therapeutic agents, that we term "matrix biologics".

Exogenous inter-α inhibitor proteins prevent cell death and improve ischemic stroke outcomes in mice

Inter-α inhibitor proteins (IAIPs) are a family of endogenous plasma and extracellular matrix molecules. IAIPs suppress proinflammatory cytokines, limit excess complement activation, and bind extracellular histones to form IAIP-histone complexes, leading to neutralization of histone-associated cytotoxicity in models of sepsis. Many of these detrimental processes also play critical roles in the pathophysiology of ischemic stroke. In this study, we first assessed the clinical relevance of IAIPs in stroke and then tested the therapeutic efficacy of exogenous IAIPs in several experimental stroke models. IAIP levels were reduced in both ischemic stroke patients and in mice subjected to experimental ischemic stroke when compared with controls. Post-stroke administration of IAIP significantly improved stroke outcomes across multiple stroke models, even when given 6 hours after stroke onset. Importantly, the beneficial effects of delayed IAIP treatment were observed in both young and aged mice. Using targeted gene expression analysis, we identified a receptor for complement activation, C5aR1, that was highly suppressed in both the blood and brain of IAIP-treated animals. Subsequent experiments using C5aR1-knockout mice demonstrated that the beneficial effects of IAIPs are mediated in part by C5aR1. These results indicate that IAIP is a potential therapeutic candidate for the treatment of ischemic stroke.

Hyaluronan interactions with innate immunity in lung biology

Lung disease is a leading cause of morbidity and mortality worldwide. Innate immune responses in the lung play a central role in the pathogenesis of lung disease and the maintenance of lung health, and thus it is crucial to understand factors that regulate them. Hyaluronan is ubiquitous in the lung, and its expression is increased following lung injury and in disease states. Furthermore, hyaladherins like inter-α-inhibitor, tumor necrosis factor-stimulated gene 6, pentraxin 3 and versican are also induced and help form a dynamic hyaluronan matrix in injured lung. This review synthesizes present knowledge about the interactions of hyaluronan and its associated hyaladherins with the lung immune system, and the implications of these interactions for lung biology and disease.

A Proteomic Approach Identifies Candidate Early Biomarkers to Predict Severe Dengue in Children

BACKGROUND

Severe dengue with severe plasma leakage (SD-SPL) is the most frequent of dengue severe form. Plasma biomarkers for early predictive diagnosis of SD-SPL are required in the primary clinics for the prevention of dengue death.

METHODOLOGY

Among 63 confirmed dengue pediatric patients recruited, hospital based longitudinal study detected six SD-SPL and ten dengue with warning sign (DWS). To identify the specific proteins increased or decreased in the SD-SPL plasma obtained 6-48 hours before the shock compared with the DWS, the isobaric tags for relative and absolute quantification (iTRAQ) technology was performed using four patients each group. Validation was undertaken in 6 SD-SPL and 10 DWS patients.

PRINCIPAL FINDINGS

Nineteen plasma proteins exhibited significantly different relative concentrations (p<0.05), with five over-expressed and fourteen under-expressed in SD-SPL compared with DWS. The individual protein was classified to either blood coagulation, vascular regulation, cellular transport-related processes or immune response. The immunoblot quantification showed angiotensinogen and antithrombin III significantly increased in SD-SPL whole plasma of early stage compared with DWS subjects. Even using this small number of samples, antithrombin III predicted SD-SPL before shock occurrence with accuracy.

CONCLUSION

Proteins identified here may serve as candidate predictive markers to diagnose SD-SPL for timely clinical management. Since the number of subjects are small, so further studies are needed to confirm all these biomarkers.

Novel interactions of domain III from the envelope glycoprotein of dengue 2 virus with human plasma proteins

Blood cells and plasma are important media for the four serotypes of dengue virus (DENV1-4) spreading into an infected person. Thus, interactions with human plasma proteins are expected to be decisive in the course of the viral infection. Affinity purification followed by MS analysis (AP/MS) was used to isolate and identify plasma-derived proteins capable to interact with a recombinant protein comprising the domain III of the envelope protein of DENV2 (DIIIE2). The elution of the AP potently inhibits DENV2 infection. Twenty-nine proteins were identified using a label-free approach as specifically captured by DIIIE2. Of these, a direct interaction with C reactive protein, thrombin and Inter-alpha-inhibitor complexes was confirmed by ELISA. Results provide further evidence of a significant representation of proteins from complement and coagulation cascades on DENV2 interactome in human plasma and stand out the domain III of the viral envelope protein as participant on these interactions. A functional clustering analysis highlights the presence of three structural motifs among putative DIIIE2-binding proteins: hydroxylation and EGF-like calcium-binding- and Gla domains.

BIOLOGICAL SIGNIFICANCE

Early cycles of dengue virus replication take place in human blood cells. Thus, the characterization of the interactome of dengue virus proteins in human plasma can lead to the identification of pivotal interactions for the infection that can eventually constitute the target for the development of methods to control dengue virus-caused disease. In this work we identified 29 proteins from human plasma that potentially interact with the envelope protein of dengue 2 virus either directly or through co-complex formation. C reactive protein, thrombin and Inter-alpha-inhibitor complexes were validated as interactors of the domain III of the envelope protein of dengue 2. Results highlight the presence of three structural motifs among putative DIIIE2-binding proteins: hydroxylation and EGF-like calcium-binding- and Gla domains. This finding together with the participation of domain III of the envelope protein on the interactions with human plasma proteins should contribute to a better understanding of dengue virus interactome in human plasma. Such knowledge can contribute to the development of more effective treatments to infected persons.

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.

Potential prognostic markers for predicting onset of dengue hemorrhagic fever

Dengue is fast evolving as a global infectious disease with more than 390 million infections reported annually. Despite the considerable amount of research, there are no effective vaccines for dengue and the clinical management of the disease solely relies on the effective medical care and supportive treatment of the patients. Rapid diagnosis and early prediction of the severity of the disease will not only aid the clinical management of the disease but also enable efficient utilization of the medical resources in the resource-poor dengue endemic regions. In this review, we have focused on certain diagnostic and prognostic biomarkers for dengue infection which could have a predictive potential for disease severity in the clinical scenario.

Discovery and characterization of potential prognostic biomarkers for dengue hemorrhagic fever

Half a million patients are hospitalized with severe dengue every year, many of whom would die without timely, appropriate clinical intervention. The majority of dengue cases are uncomplicated; however, 2-5% progress to severe dengue. Severe dengue cases have been reported with increasing frequency over the last 30 years. To discover biomarkers for severe dengue, we used surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to analyze dengue virus positive serum samples from the acute phase of infection. Using this method, 16 proteins were identified as candidate biomarkers for severe dengue. From these 16 biomarkers, three candidates were selected for confirmation by enzyme-linked immunosorbent assay and Western blot: vitronectin (Vtn, 55.1 kDa), hemopexin (Hx, 52.4 kDa), and serotransferrin (Tf, 79.2 kDa). Vitronectin, Hx, and Tf best differentiated between dengue and severe dengue.

Elevated levels of cell-free circulating DNA in patients with acute dengue virus infection

Background

Apoptosis is thought to play a role in the pathogenesis of severe dengue and the release of cell-free DNA into the circulatory system in several medical conditions. Therefore, we investigated circulating DNA as a potential biomarker for severe dengue.

Methods and Findings

A direct fluorometric degradation assay using PicoGreen was performed to quantify cell-free DNA from patient plasma. Circulating DNA levels were significantly higher in patients with dengue virus infection than with other febrile illnesses and healthy controls. Remarkably, the increase of DNA levels correlated with the severity of dengue. Additionally, multivariate logistic regression analysis showed that circulating DNA levels independently correlated with dengue shock syndrome.

Conclusions

Circulating DNA levels were increased in dengue patients and correlated with dengue severity. Additional studies are required to show the benefits of this biomarker in early dengue diagnosis and for the prognosis of shock complication.