Respiratory syncytial virus infection: why does disease severity vary among individuals?

Introduction: Respiratory syncytial virus (RSV) is the most common cause of acute lower respiratory tract infections in infancy. While many infants are infected with RSV, the nature and severity of the disease vary among individuals. RSV causes bronchiolitis, pneumonia, and asthma exacerbation. However, most children infected with RSV have only mild upper airways disease and may be asymptomatic. Areas covered: Despite efforts to elucidate mechanisms for the various clinical responses to RSV infection, they remain largely unknown, suggesting that susceptibility and disease are influenced by multiple intrinsic and extrinsic factors. This article reviews the available literature on the field of RSV disease severity and discusses important factors associated to susceptibility and different disease outcome. Expert opinion: The severity of RSV-induced illness is a phenomenon that depends on a variety of graded mechanisms of interaction between the host, virus, and environment. This may lead to differences in the intensity of immune response in the lung and different courses of the disease. By characterizing, classifying, and grading the affecting factors in high-risk patients versus those who do not fall ill by RSV, we may find therapies or point to disease-limiting medications. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group

COVID-19: Why does disease severity vary among individuals?

The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is responsible for the current pandemic, coronavirus disease 2019 (COVID-19). While all people are susceptible to the SARS-CoV-2 infection, the nature and severity of the disease vary significantly among individuals and populations. Importantly, reported disease burdens and case fatality rates differ considerably from country to country. There are, however, still uncertainties about the severity of the disease among individuals or the reason behind a more severe disease in some cases. There is a strong possibility that the severity of this disease depends on a complicated interaction between the host, virus, and environment, which leads to different clinical outcomes. The objective of this article is to point out the essential influential factors related to the host, virus, and environment affecting the clinical outcome of COVID-19. © 2021 Elsevier Lt

Functional variation (Q63R) in the cannabinoid CB2 receptor may affect the severity of COVID-19: a human study and molecular docking

Evidence supports a role of host genetic diversity in the clinical course of coronavirus disease 2019 (COVID-19). Variation in the cannabinoid CB2 receptor gene (CNR2) could affect the regulatory action of endocannabinoids on the immune system, resulting in an increased risk of various inflammatory diseases. The present study investigated the relationship between the CNR2-Q63R variant and COVID-19 severity. A total of 200 Iranian COVID-19 patients were enrolled in the study and genotyped using a TaqMan assay. The co-dominant, dominant, recessive, over-dominant, and additive inheritance models were analyzed using SNPStats software. In silico molecular docking was also performed to simulate the effects of the Q63R variation on CB2 binding with a ligand and with the G-protein. A significant difference in the Q63R allele and genotype distribution was found between expired and discharged COVID-19 patients in co-dominant, recessive, and additive inheritance models. The molecular docking results showed that the predicted structure of mutant CB2 (63R type) could not bind to the G-protein in the correct position. The data indicated that the Q63R variation in the CNR2 gene may affect the severity of COVID-19. Identification of genes related to susceptibility and severity of COVID-19 may lead to specific targets for drug repurposing or development. Graphic abstract: Figure not available: see fulltext. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature

Neutrophils in respiratory syncytial virus infection: From harmful effects to therapeutic opportunities

Respiratory syncytial virus (RSV) is an important infectious agent in infants and young children. In most cases, RSV infection only causes mild disease, but in some, it requires invasive ventilation. Although antiviral drugs are obvious candidates to treat viral illness, and some have shown antiviral effects in humans, antivirals such as GS-5806, ALX-0171 and ALS-8176 have not yet met their expectations. Since the inappropriate or dysregulated immune response against RSV leads to harmful immune pathology, a robust immune cascade is probably underway by the time patients reach the hospital. RSV infection is associated with a strong neutrophil influx into the airway. It not clear if these cells contribute to antiviral defence or to lung pathology. This article discusses the protective and harmful roles of neutrophils during RSV infection and provides an overview of mechanisms by which neutrophil function could be targeted to prevent tissue injury and preserve homeostasis. © 2020 The British Pharmacological Societ

Neutrophils in respiratory syncytial virus infection: From harmful effects to therapeutic opportunities

Respiratory syncytial virus (RSV) is an important infectious agent in infants and young children. In most cases, RSV infection only causes mild disease, but in some, it requires invasive ventilation. Although antiviral drugs are obvious candidates to treat viral illness, and some have shown antiviral effects in humans, antivirals such as GS-5806, ALX-0171 and ALS-8176 have not yet met their expectations. Since the inappropriate or dysregulated immune response against RSV leads to harmful immune pathology, a robust immune cascade is probably underway by the time patients reach the hospital. RSV infection is associated with a strong neutrophil influx into the airway. It not clear if these cells contribute to antiviral defence or to lung pathology. This article discusses the protective and harmful roles of neutrophils during RSV infection and provides an overview of mechanisms by which neutrophil function could be targeted to prevent tissue injury and preserve homeostasis. © 2020 The British Pharmacological Societ

Ten challenging questions about SARS-CoV-2 and COVID-19

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recently introduced as a global public health problem by the World Health Organization (WHO). The virus outbreak has been documented around the world. Updating data in different aspects of the virus could force us to revise our idea about the main questions concerning coronavirus disease-19 (COVID-19). Areas covered: Although our knowledge about the SARS-CoV-2 and COVID-19 is largely based on the very limited data, the information is growing rapidly. The renewed answers to the specific research questions concerning updating data not only reveal gaps for future research but also re-categorized our information. Here, we attempt to briefly discuss 10 important questions about SARS-CoV-2 and COVID-19. Expert opinion: Since our knowledge about different aspects of SARS-CoV-2 appears to be in its infancy and is rapidly changing, the provision of the right data is more difficult in this regard. However, we try to rely on results from more extensive research to answer the main questions about this new virus. Therefore, further studies, particularly in the context of the virus pathogenesis, diagnosis, treatment, and vaccine development, are warranted. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group

Anti-inflammatory effects of curcumin-loaded niosomes on respiratory syncytial virus infection in a mice model

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in paediatrics. While antivirals are apparent candidates to treat RSV-induced diseases, they have not yet met expectations and have remained in infancy. There is growing evidence to suggest that modulating the exacerbated inflammation during RSV infection can improve disease outcome. Curcumin-loaded niosomes have anti-inflammatory effects against RSV-induced respiratory disease by reducing immune cells' infiltration and inflammatory cytokines' production. This study evaluated the effects of curcumin-loaded niosomes on RSV-induced immunopathology in a mice model. Curcumin-loaded niosomes were prepared using the thin-film hydration method and characterized in vitro. Female Balb/c mice were infected by RSV-A2 and treated daily with curcumin-loaded niosomes. The potential anti-inflammatory effects of curcumin-loaded niosomes were evaluated on day 5 after infection. Using curcumin-loaded niosomes decreased immune cell influx and the inflammatory mediators (MIP-1α, TNF-α and IFN-γ) production in the lung, resulting in alleviated lung pathology following RSV infection. These findings indicate that curcumin-loaded niosomes have anti-inflammatory potential and could be a promising candidate to alleviate RSV-associated immunopathology

Cannabinoid CB2 Receptor Functional Variation (Q63R) Is Associated with Multiple Sclerosis in Iranian Subjects

The cannabinoid system has been identified as a critical endogenous regulator of immune homeostasis through immunomodulatory actions. This system is one of the main regulatory systems of the central nervous system (CNS). Variations in the cannabinoid CB2 receptor gene (CNR2) could affect intracellular signaling and reduce system function, which has been associated with an unbalanced immune response and increased risk of a variety of autoimmune inflammatory disorders. The present study investigated the relationship between CNR2 rs35761398 (Q63R) functional variation and multiple sclerosis (MS). A total of 100 Iranian MS patients and 100 healthy controls were enrolled in the study and genotyped through TaqMan assay. The co-dominant, dominant, recessive, over-dominant, and additive inheritance models were analyzed using SNPStats software. A significant genetic association was observed between Q63R polymorphism and MS. The dominant model was accepted as the best inheritance model to fit the data (OR 2.70, 95 CI 1.47�4.97, p = 0.001). The data implied the involvement of the CNR2 gene in susceptibility to MS in Iranian patients. © 2019, Springer Science+Business Media, LLC, part of Springer Nature