scholarly journals Neutrophil Recruitment and Participation in Severe Diseases Caused by Flavivirus Infection

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 717
Author(s):  
Marina Alves Fontoura ◽  
Rebeca Fróes Rocha ◽  
Rafael Elias Marques
Keyword(s):  
Complex Disease ◽  
Viral Infections ◽  
Fungal Infections ◽  
Severe Disease ◽  
Hemorrhagic Fever ◽  
Experimental Models ◽  
Neutrophil Recruitment ◽  
Comprehensive Overview ◽  
Flavivirus Infection

Neutrophils are first-line responders to infections and are recruited to target tissues through the action of chemoattractant molecules, such as chemokines. Neutrophils are crucial for the control of bacterial and fungal infections, but their role in the context of viral infections has been understudied. Flaviviruses are important human viral pathogens transmitted by arthropods. Infection with a flavivirus may result in a variety of complex disease manifestations, including hemorrhagic fever, encephalitis or congenital malformations. Our understanding of flaviviral diseases is incomplete, and so is the role of neutrophils in such diseases. Here we present a comprehensive overview on the participation of neutrophils in severe disease forms evolving from flavivirus infection, focusing on the role of chemokines and their receptors as main drivers of neutrophil function. Neutrophil activation during viral infection was shown to interfere in viral replication through effector functions, but the resulting inflammation is significant and may be detrimental to the host. For congenital infections in humans, neutrophil recruitment mediated by CXCL8 would be catastrophic. Evidence suggests that control of neutrophil recruitment to flavivirus-infected tissues may reduce immunopathology in experimental models and patients, with minimal loss to viral clearance. Further investigation on the roles of neutrophils in flaviviral infections may reveal unappreciated functions of this leukocyte population while increasing our understanding of flaviviral disease pathogenesis in its multiple forms.

scholarly journals Viruses and Type 1 Diabetes: From Enteroviruses to the Virome

2021 ◽  
Vol 9 (7) ◽  
pp. 1519
Author(s):  
Sonia R. Isaacs ◽  
Dylan B. Foskett ◽  
Anna J. Maxwell ◽  
Emily J. Ward ◽  
Clare L. Faulkner ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Viral Infections ◽  
Antiviral Drug ◽  
Virus Detection ◽  
Detection Methods ◽  
Islet Autoimmunity ◽  
Comprehensive Overview ◽  
Drug Candidates

For over a century, viruses have left a long trail of evidence implicating them as frequent suspects in the development of type 1 diabetes. Through vigorous interrogation of viral infections in individuals with islet autoimmunity and type 1 diabetes using serological and molecular virus detection methods, as well as mechanistic studies of virus-infected human pancreatic β-cells, the prime suspects have been narrowed down to predominantly human enteroviruses. Here, we provide a comprehensive overview of evidence supporting the hypothesised role of enteroviruses in the development of islet autoimmunity and type 1 diabetes. We also discuss concerns over the historical focus and investigation bias toward enteroviruses and summarise current unbiased efforts aimed at characterising the complete population of viruses (the “virome”) contributing early in life to the development of islet autoimmunity and type 1 diabetes. Finally, we review the range of vaccine and antiviral drug candidates currently being evaluated in clinical trials for the prevention and potential treatment of type 1 diabetes.

scholarly journals Neutrophils in respiratory viral infections

2021 ◽  
Author(s):  
Cecilia Johansson ◽  
Freja C. M. Kirsebom
Keyword(s):  
Viral Infections ◽  
Immune Cell ◽  
Respiratory Infections ◽  
Fungal Infections ◽  
Severe Disease ◽  
The Elderly ◽  
Viral Control ◽  
Immunological Mechanisms ◽  
Respiratory Viral Infections ◽  
Viral Respiratory Infections

AbstractViral respiratory infections are a common cause of severe disease, especially in infants, people who are immunocompromised, and in the elderly. Neutrophils, an important innate immune cell, infiltrate the lungs rapidly after an inflammatory insult. The most well-characterized effector mechanisms by which neutrophils contribute to host defense are largely extracellular and the involvement of neutrophils in protection from numerous bacterial and fungal infections is well established. However, the role of neutrophils in responses to viruses, which replicate intracellularly, has been less studied. It remains unclear whether and, by which underlying immunological mechanisms, neutrophils contribute to viral control or confer protection against an intracellular pathogen. Furthermore, neutrophils need to be tightly regulated to avoid bystander damage to host tissues. This is especially relevant in the lung where damage to delicate alveolar structures can compromise gas exchange with life-threatening consequences. It is inherently less clear how neutrophils can contribute to host immunity to viruses without causing immunopathology and/or exacerbating disease severity. In this review, we summarize and discuss the current understanding of how neutrophils in the lung direct immune responses to viruses, control viral replication and spread, and cause pathology during respiratory viral infections.

scholarly journals Role of unfolded proteins in lung disease

Thorax ◽  
2020 ◽  
Vol 76 (1) ◽  
pp. 92-99
Author(s):  
Kirsty L Bradley ◽  
Clare A Stokes ◽  
Stefan J Marciniak ◽  
Lisa C Parker ◽  
Alison M Condliffe
Keyword(s):  
Protein Synthesis ◽  
Er Stress ◽  
Respiratory Diseases ◽  
Viral Infections ◽  
Genetic Manipulation ◽  
Experimental Models ◽  
Misfolded Proteins ◽  
Pharmacological Agents ◽  
The Impact

The lungs are exposed to a range of environmental toxins (including cigarette smoke, air pollution, asbestos) and pathogens (bacterial, viral and fungal), and most respiratory diseases are associated with local or systemic hypoxia. All of these adverse factors can trigger endoplasmic reticulum (ER) stress. The ER is a key intracellular site for synthesis of secretory and membrane proteins, regulating their folding, assembly into complexes, transport and degradation. Accumulation of misfolded proteins within the lumen results in ER stress, which activates the unfolded protein response (UPR). Effectors of the UPR temporarily reduce protein synthesis, while enhancing degradation of misfolded proteins and increasing the folding capacity of the ER. If successful, homeostasis is restored and protein synthesis resumes, but if ER stress persists, cell death pathways are activated. ER stress and the resulting UPR occur in a range of pulmonary insults and the outcome plays an important role in many respiratory diseases. The UPR is triggered in the airway of patients with several respiratory diseases and in corresponding experimental models. ER stress has been implicated in the initiation and progression of pulmonary fibrosis, and evidence is accumulating suggesting that ER stress occurs in obstructive lung diseases (particularly in asthma), in pulmonary infections (some viral infections and in the setting of the cystic fibrosis airway) and in lung cancer. While a number of small molecule inhibitors have been used to interrogate the role of the UPR in disease models, many of these tools have complex and off-target effects, hence additional evidence (eg, from genetic manipulation) may be required to support conclusions based on the impact of such pharmacological agents. Aberrant activation of the UPR may be linked to disease pathogenesis and progression, but at present, our understanding of the context-specific and disease-specific mechanisms linking these processes is incomplete. Despite this, the ability of the UPR to defend against ER stress and influence a range of respiratory diseases is becoming increasingly evident, and the UPR is therefore attracting attention as a prospective target for therapeutic intervention strategies.

scholarly journals The Regulation of Flavivirus Infection by Hijacking Exosome-Mediated Cell–Cell Communication: New Insights on Virus–Host Interactions

Viruses ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 765
Author(s):  
José Manuel Reyes-Ruiz ◽  
Juan Fidel Osuna-Ramos ◽  
Luis Adrián De Jesús-González ◽  
Selvin Noé Palacios-Rápalo ◽  
Carlos Daniel Cordero-Rivera ◽  
...  
Keyword(s):  
Viral Infections ◽  
Cell Communication ◽  
Cell Interaction ◽  
Host Cells ◽  
Human Pathogens ◽  
Cellular Functions ◽  
Cellular Targets ◽  
Host Interaction ◽  
Flavivirus Infection

The arthropod-borne flaviviruses are important human pathogens, and a deeper understanding of the virus–host cell interaction is required to identify cellular targets that can be used as therapeutic candidates. It is well reported that the flaviviruses hijack several cellular functions, such as exosome-mediated cell communication during infection, which is modulated by the delivery of the exosomal cargo of pro- or antiviral molecules to the receiving host cells. Therefore, to study the role of exosomes during flavivirus infections is essential, not only to understand its relevance in virus–host interaction, but also to identify molecular factors that may contribute to the development of new strategies to block these viral infections. This review explores the implications of exosomes in flavivirus dissemination and transmission from the vector to human host cells, as well as their involvement in the host immune response. The hypothesis about exosomes as a transplacental infection route of ZIKV and the paradox effect or the dual role of exosomes released during flavivirus infection are also discussed here. Although several studies have been performed in order to identify and characterize cellular and viral molecules released in exosomes, it is not clear how all of these components participate in viral pathogenesis. Further studies will determine the balance between protective and harmful exosomes secreted by flavivirus infected cells, the characteristics and components that distinguish them both, and how they could be a factor that determines the infection outcome.

scholarly journals Viruses and Type 1 Diabetes: From Enteroviruses to the Virome

2021 ◽  
Author(s):  
Sonia R Isaacs ◽  
Dylan B Foskett ◽  
Anna J Maxwell ◽  
Emily J Ward ◽  
Clare L Faulkner ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Viral Infections ◽  
Antiviral Drug ◽  
Virus Detection ◽  
Detection Methods ◽  
Islet Autoimmunity ◽  
Comprehensive Overview ◽  
Drug Candidates

For over a century, viruses have left a long trail of evidence implicating them as frequent suspects in the development of type 1 diabetes. Through vigorous interrogation of viral infections in individuals with islet autoimmunity and type 1 diabetes using serological and molecular virus detection methods, and mechanistic studies of virus infected human pancreatic β-cells, the prime suspects have been narrowed down to predominantly human enteroviruses. Here we provide a comprehensive overview of evidence supporting the hypothesised role of enteroviruses in the development of islet autoimmunity and type 1 diabetes. We also discuss concerns over the historical focus and investigation bias toward enteroviruses, and summarise current unbiased efforts aimed at characterising the complete population of viruses (the “virome”) contributing early in life to the development of islet autoimmunity and type 1 diabetes. Finally, we review the range of vaccine and antiviral drug candidates currently being evaluated in clinical trials for the prevention and potential treatment of type 1 diabetes.

scholarly journals Novel insights into the metabolic action of Kiss1 neurons

2020 ◽  
Vol 9 (5) ◽  
pp. R124-R133 ◽  
Author(s):  
Rajae Talbi ◽  
Victor M Navarro
Keyword(s):  
Arcuate Nucleus ◽  
Pulse Generator ◽  
Experimental Models ◽  
Close Apposition ◽  
Comprehensive Overview ◽  
Regulation Of Metabolism ◽  
Gnrh Release ◽  
Recent Developments ◽  
Metabolic Action

Kiss1 neurons are essential regulators of the hypothalamic–pituitary–gonadal (HPG) axis by regulating gonadotropin-releasing hormone (GnRH) release. Compelling evidence suggests that Kiss1 neurons of the arcuate nucleus (Kiss1ARC), recently identified as the hypothalamic GnRH pulse generator driving fertility, also participate in the regulation of metabolism through kisspeptinergic and glutamatergic interactions with, at least, proopiomelanocortin (POMC) and agouti-related peptide (AgRP)/neuropeptide Y (NPY) neurons, located in close apposition with Kiss1ARC. This review offers a comprehensive overview of the recent developments, mainly derived from animal models, on the role of Kiss1 neurons in the regulation of energy balance, including food intake, energy expenditure and the influence of circadian rhythms on this role. Furthermore, the possible neuroendocrine pathways underlying this effect, and the existing controversies related to the anorexigenic action of kisspeptin in the different experimental models, are also discussed.

scholarly journals Zinc, Vitamin D and Vitamin C: Perspectives for COVID-19 With a Focus on Physical Tissue Barrier Integrity

2020 ◽  
Vol 7 ◽  
Author(s):  
José João Name ◽  
Ana Carolina Remondi Souza ◽  
Andrea Rodrigues Vasconcelos ◽  
Pietra Sacramento Prado ◽  
Carolina Parga Martins Pereira
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Viral Infections ◽  
Adequate Intake ◽  
High Demand ◽  
Comprehensive Overview ◽  
Disease Prognosis ◽  
Mucous Membranes ◽  
And Function

Some nutrients play key roles in maintaining the integrity and function of the immune system, presenting synergistic actions in steps determinant for the immune response. Among these elements, zinc and vitamins C and D stand out for having immunomodulatory functions and for playing roles in preserving physical tissue barriers. Considering the COVID-19 pandemic, nutrients that can optimize the immune system to prevent or lower the risk of severe progression and prognosis of this viral infection become relevant. Thus, the present review aims to provide a comprehensive overview of the roles of zinc and vitamins C and D in the immune response to viral infections, focusing on the synergistic action of these nutrients in the maintenance of physical tissue barriers, such as the skin and mucous membranes. The evidence found in the literature shows that deficiency of one or more of these three elements compromises the immune response, making an individual more vulnerable to viral infections and to a worse disease prognosis. Thus, during the COVID-19 pandemic, the adequate intake of zinc and vitamins C and D may represent a promising pharmacological tool due to the high demand for these nutrients in the case of contact with the virus and onset of the inflammatory process. Ongoing clinical trials will help to clarify the role of these nutrients for COVID-19 management.

scholarly journals Inhibition of Type 1 Cytokine–mediated Inflammation by a Soluble CD30 Homologue Encoded by Ectromelia (Mousepox) Virus

2002 ◽  
Vol 196 (6) ◽  
pp. 829-839 ◽  
Author(s):  
Margarida Saraiva ◽  
Philip Smith ◽  
Padraic G. Fallon ◽  
Antonio Alcami
Keyword(s):  
Viral Infections ◽  
Inflammatory Responses ◽  
Severe Disease ◽  
Interferon Γ ◽  
Reverse Signaling ◽  
Soluble Cd30

CD30 is up-regulated in several human diseases and viral infections but its role in immune regulation is poorly understood. Here, we report the expression of a functional soluble CD30 homologue, viral CD30 (vCD30), encoded by ectromelia (mousepox) virus, a poxvirus that causes a severe disease related to human smallpox. We show that vCD30 is a 12-kD secreted protein that not only binds CD30L with high affinity and prevents its interaction with CD30, but it also induces reverse signaling in cells expressing CD30L. vCD30 blocked the generation of interferon γ–producing cells in vitro and was a potent inhibitor of T helper cell (Th)1- but not Th2-mediated inflammation in vivo. The finding of a CD30 homologue encoded by ectromelia virus suggests a role for CD30 in antiviral defense. Characterization of the immunological properties of vCD30 has uncovered a role of CD30–CD30L interactions in the generation of inflammatory responses.

scholarly journals Structural basis for recognition and regulation of arenavirus polymerase L by Z protein

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Huiling Kang ◽  
Jingyuan Cong ◽  
Chenlong Wang ◽  
Wenxin Ji ◽  
Yuhui Xin ◽  
...  
Keyword(s):  
Rational Design ◽  
Viral Infections ◽  
Hemorrhagic Fever ◽  
Structural Basis ◽  
Exit Site ◽  
L Protein ◽  
Argentine Hemorrhagic Fever ◽  
L Proteins ◽  
Z Protein

AbstractJunin virus (JUNV) causes Argentine hemorrhagic fever, a debilitating human disease of high mortality rates and a great risk to public health worldwide. Studying the L protein that replicates and transcribes the genome of JUNV, and its regulator Z protein should provide critical clues to identify therapeutic targets for disrupting the life cycle of JUNV. Here we report the 3.54 Å cryo-EM structure of the JUNV L protein complexed with regulator Z protein. JUNV L structure reveals a conserved architecture containing signature motifs found in other L proteins. Structural analysis shows that L protein is regulated by binding of Z protein at the RNA product exit site. Based on these findings, we propose a model for the role of Z protein as a switch to turn on/off the viral RNA synthesis via its interaction with L protein. Our work unveils the mechanism of JUNV transcription, replication and regulation, which provides a framework for the rational design of antivirals for combating viral infections.

scholarly journals Viral-induced inflammatory coagulation disorders: Preparing for another epidemic

2021 ◽  
Author(s):  
Toshiaki Iba ◽  
JH Levy ◽  
Marcel Levi
Keyword(s):  
Infectious Diseases ◽  
Climate Changes ◽  
Viral Infections ◽  
Hemorrhagic Fever ◽  
Lessons Learned ◽  
Hemorrhagic Fevers ◽  
Recent Climate ◽  
Viral Hemorrhagic Fevers ◽  
Life Threatening

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.

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